KR20230120495A - Organic-inorganic hybrid polymer electrolyte having a multi-layer structure in which a content of inorganic particles is controlled, manufacturing method thereof, and all-solid-state battery comprising the same - Google Patents

Abstract

The present invention relates to an organic-inorganic hybrid polymer electrolyte having a multi-layered structure in which the content of inorganic particles is controlled, a manufacturing method thereof, and an all-solid-state lithium secondary battery including the same, wherein the organic-inorganic hybrid polymer electrolyte includes sequentially stacked first to N^th electrolyte layers, the first to N^th electrolyte layers each include a polymer matrix and inorganic particles, and the content of the inorganic particles increases from the first electrolyte layer to the N^th electrolyte layer or from the N^th electrolyte layer to the first electrolyte layer.

Description

Organic-inorganic hybrid polymer electrolyte having a multi-layer structure in which the content of inorganic particles is controlled, manufacturing method thereof, and all-solid-state battery including the same method thereof, and all-solid-state battery comprising the same}

The present invention relates to an organic-inorganic hybrid polymer electrolyte having a multilayer structure in which the content of inorganic particles is controlled, a method for preparing the same, and an all-solid-state battery including the same.

Lithium secondary batteries have far superior energy storage capacity and lifespan compared to existing secondary batteries (lead storage batteries, nickel metal hydride).

Applications of the lithium secondary battery are expanding not only to portable devices but also to electric vehicles. Specifically, internal combustion engine vehicles using fossil fuels are gradually being replaced by electric vehicles using lithium ion batteries. If electric vehicles are fully commercialized, air pollution and global warming caused by fossil fuels can be reduced, and in the long term, It will be of great significance to preserve the living environment. In addition, lithium ion batteries are applied to energy storage systems (ESS), which are essential for renewable systems such as wind power and solar power.

As such, lithium secondary batteries used in various applications have conventionally been dominated by lithium ion batteries containing liquid electrolytes, and the lithium ion batteries are composed of a positive electrode, a negative electrode, an electrolyte, and a separator, and are composed of a fire or explosion case. is reported consistently. The organic liquid electrolyte of the lithium ion battery is ignitable, and once it catches fire, it is difficult to extinguish the fire and there is a risk of leading to a series of fires. Because of this risk of fire, concerns about the thermal safety of lithium-ion batteries are growing, such as regulations prohibiting carrying more than 160Wh capacity on airplanes.

In addition, it is pointed out that the price of the lithium ion battery is expensive and is not environmentally friendly. Lithium and cobalt, which are key materials for lithium-ion batteries, are rare metals with limited resources, and prices are rising due to increased demand. In order to mine metals that are distributed in extremely small amounts on Earth, mining activities are required and various processes must be performed to obtain high-purity rare metals. In this process, a lot of energy is consumed and the environment is destroyed. In addition, waste lithium batteries that have already been used may emit pollutants if left unattended for a long period of time. Research is needed to find materials that can replace rare metals or to minimize their use.

On the other hand, among lithium secondary batteries, all-solid-state batteries using solid-state electrolytes do not require safety devices and separators in preparation for temperature changes and external shocks, so cost reduction and high capacity can be realized with the same size. Specifically, since there is no risk of fire, energy density can be increased by additionally filling the space where the cooling device, which occupies 30% or more of the space of the battery pack, is removed with battery cells. In addition, since there is no need for a separator that prevents electrical shorts by physically blocking the positive and negative electrodes in liquid electrolyte, volume reduction and cost reduction are possible. On the other hand, the all-solid-state battery can have a multipolar structure and can reduce the volume.

However, compared to liquid electrolytes, the solid electrolyte has a low battery output due to a low movement speed of lithium ions, and a high interface resistance between the electrolyte and the anode/cathode, so the lifespan is lower than that of conventional batteries. In order to improve the low ionic conductivity and interface resistance between the anode/cathode and the solid electrolyte, research on various solid electrolytes such as oxide (LLZO), polymer, and sulfide (LGPS) is being conducted, but there is still a difference from the performance of liquid electrolytes. exist.

On the other hand, as a next-generation lithium secondary battery, a lithium metal battery using a lithium metal anode material instead of the existing graphite anode material has been developed to improve energy density. there is Dendrite is a crystal that accumulates in the shape of a tree branch from the surface of lithium metal and hinders the movement of lithium ions, resulting in problems such as reduced charge/discharge efficiency, short circuit, and shortened lifespan.

Therefore, in order to commercially use an all-solid-state battery using lithium metal as an anode material, problems to improve performance and solve the dendrite generation problem remain.

Korean Patent Publication No. 10-2018-0138134

An object of the present invention is to provide an organic-inorganic hybrid polymer electrolyte having a multilayer structure in which the content of inorganic particles is controlled, a method for preparing the same, and an all-solid-state lithium secondary battery including the same.

Another object of the present invention is to provide an organic-inorganic hybrid polymer electrolyte for an all-solid-state lithium secondary battery capable of improving battery performance and suppressing dendrite growth.

Another object of the present invention is to provide a hybrid polymer electrolyte having an integrated structure of a separator and an electrolyte.

The problem to be solved by the present invention is not limited to the above-mentioned problem (s), and another problem (s) not mentioned will be clearly understood by those skilled in the art from the following description.

In order to achieve the above object, the present invention includes sequentially stacked first to Nth electrolyte layers, wherein the first to Nth electrolyte layers each include a polymer matrix and inorganic particles, and the first to Nth electrolyte layers each include a polymer matrix and inorganic particles. Provided is an organic-inorganic hybrid polymer electrolyte having a multilayer structure in which the content of inorganic particles increases from the electrolyte layer to the Nth electrolyte layer or from the Nth electrolyte layer to the first electrolyte layer, and the content of the inorganic particles is controlled.

According to one embodiment of the present invention, the inorganic particles may be a carbon-based material.

According to one embodiment of the present invention, the inorganic particles may be carbon nitride.

According to one embodiment of the present invention, the N may be 2 to 5.

According to one embodiment of the present invention, the content of the inorganic particles included in the first electrolyte layer may increase from the Nth electrolyte layer.

According to one embodiment of the present invention, a difference in content of the inorganic particles between the N-th electrolyte layer and the N−1-th electrolyte layer may be 3% to 10% by weight.

According to one embodiment of the present invention, the organic-inorganic hybrid polymer electrolyte consists of a first electrolyte layer and a second electrolyte layer formed on one surface of the first electrolyte layer, and the content of inorganic particles included in the first electrolyte layer A content of silver may be higher than that of inorganic particles included in the second electrolyte layer.

According to one embodiment of the present invention, the content of the inorganic particles included in the first electrolyte layer is 5 parts by weight to 15 parts by weight based on the total 100 parts by weight of the polymer matrix included in the first electrolyte layer, and the second The content of the inorganic particles included in the electrolyte layer may be 1.5 parts by weight to 6 parts by weight based on 100 parts by weight of the entire polymer matrix included in the second electrolyte layer.

According to one embodiment of the present invention, the first electrolyte layer may further include a liquid electrolyte.

According to one embodiment of the present invention, the total thickness of the organic-inorganic hybrid polymer electrolyte may be 100 μm to 500 μm.

In addition, in order to achieve the above object, the present invention includes the step of preparing a polymer electrolyte in which the first to Nth electrolyte layers are sequentially stacked by curing the first to Nth polymer electrolyte precursor compositions, , The first to Nth polymer electrolyte precursor compositions each include a polymer matrix and inorganic particles, and from the first polymer electrolyte precursor composition to the Nth polymer electrolyte precursor composition or from the Nth polymer electrolyte precursor composition 1 Provides a method for preparing a multi-layer structured organic-inorganic hybrid polymer electrolyte in which the content of inorganic particles increases as the polymer electrolyte precursor composition increases.

In addition, in order to achieve the above object, the present invention is a negative electrode; anode; and an organic-inorganic hybrid polymer electrolyte having a multilayer structure in which the content of inorganic particles is controlled, including the organic-inorganic hybrid polymer electrolyte according to the present invention formed between the negative electrode and the positive electrode.

According to an embodiment of the present invention, an electrolyte layer having a high content of inorganic particles among the first to Nth electrolyte layers may be positioned adjacent to the negative electrode.

According to one embodiment of the present invention, the negative electrode may include lithium metal.

According to the present invention, an all-solid-state battery including an organic-inorganic hybrid polymer electrolyte having a multilayer structure in which the content of inorganic particles is controlled has an effect of improving performance and suppressing dendrite growth.

According to the present invention, there is an effect of increasing the energy density by reducing the volume and volume occupied by the separator in the battery through the organic-inorganic hybrid polymer electrolyte having an integral structure of the separator and the electrolyte.

1 is a schematic diagram showing the structure of an all-solid-state battery including an organic-inorganic hybrid polymer electrolyte according to an embodiment of the present invention.
2 is a photograph of an organic-inorganic hybrid polymer electrolyte according to an embodiment of the present invention.
3 to 6 show SEM images of the copper surface of the negative electrode after the 10th charge of the all-solid-state battery including the organic-inorganic hybrid polymer electrolyte according to an embodiment of the present invention, respectively.
7 to 13 are graphs showing the results of measuring specific capacities of all-solid-state batteries including organic-inorganic hybrid polymer electrolytes in one embodiment and comparative example of the present invention, respectively.

Before describing the present invention in detail, the terms or words used in this specification should not be construed as unconditionally limited in a conventional or dictionary sense, and in order for the inventor of the present invention to explain his/her invention in the best way It should be noted that concepts of various terms may be appropriately defined and used, and furthermore, these terms or words should be interpreted as meanings and concepts corresponding to the technical idea of the present invention.

That is, the terms used in this specification are only used to describe preferred embodiments of the present invention, and are not intended to specifically limit the contents of the present invention, and these terms represent various possibilities of the present invention. It should be noted that it is a defined term.

In addition, in this specification, it should be noted that singular expressions may include plural expressions unless the context clearly indicates otherwise, and similarly, even if they are expressed in plural numbers, they may include singular meanings. do.

Throughout this specification, when a component is described as "including" another component, it does not exclude any other component, but further includes any other component, unless otherwise stated. It can mean you can do it.

In addition, in the following description of the present invention, a detailed description of a configuration that is determined to unnecessarily obscure the subject matter of the present invention, for example, the known technology including the prior art, may be omitted.

Hereinafter, the present invention will be described in more detail.

According to the present invention, it includes sequentially stacked first to N-th electrolyte layers, wherein the first to N-th electrolyte layers each include a polymer matrix and inorganic particles, and in the first electrolyte layer, the N-th electrolyte layer An organic-inorganic hybrid polymer electrolyte having a multilayer structure in which the content of inorganic particles increases toward the electrolyte layer or from the N-th electrolyte layer to the first electrolyte layer, the content of which is controlled, is provided.

According to one embodiment of the present invention, the organic-inorganic hybrid polymer electrolyte is an all-solid body including the organic-inorganic hybrid polymer electrolyte by adjusting the content of inorganic particles included in the sequentially stacked first to Nth electrolyte layers. It is possible to improve the safety of the battery by suppressing the growth of lithium dendrites as well as improving the performance of the lithium secondary battery (hereinafter referred to as an all-solid-state battery).

According to one embodiment of the present invention, the organic-inorganic hybrid polymer electrolyte may have a structure in which N electrolyte layers are sequentially stacked, and the N may be freely adjusted as needed, and 2 to 5, 2 to 3, or 2 days can Specifically, the organic-inorganic hybrid polymer electrolyte has a structure in which first to fifth electrolyte layers are sequentially stacked, a structure in which first to third electrolyte layers are sequentially stacked, or a first electrolyte layer and a second electrolyte layer are sequentially stacked. It may have a sequentially stacked structure.

According to one embodiment of the present invention, the first to Nth electrolyte layers may each include a polymer matrix and inorganic particles.

According to one embodiment of the present invention, the polymer matrix is an ion conductive material and is not particularly limited as long as it is a polymer material commonly used as a solid polymer electrolyte (SPE) material for an all-solid-state battery, but, for example, poly Ether-based polymers, polycarbonate-based polymers, acrylate-based polymers, polysiloxane-based polymers, phosphazene-based polymers, polyethylene derivatives, alkylene oxide derivatives, phosphoric acid ester polymers, poly agitation lysine, polyester sulfide, poly Vinyl alcohol, polyvinylidene fluoride (PVdF), PVC polymer, PMMA polymer, polyacrylonitrile (PAN), polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP), ionic polymers containing dissociation groups; and the like.

In one embodiment of the present invention, the polymer matrix may be a polyether-based polymer, and as a more specific example, the polymer matrix may be polyethylene oxide (PEO).

In one embodiment of the present invention, the PEO polymer may include polyethylene glycol dimethyl ether (Poly(ethylene glycol) dimethyl ether, PEGDME).

In one embodiment of the present invention, the content of the polymer matrix included in each of the first to Nth electrolyte layers may be the same.

According to one embodiment of the present invention, the inorganic particles may include a carbon-based material. For example, the carbon-based material may include one or more hetero-elements. Here, the heterogeneous element may include nitrogen (N), oxygen (O), boron (B), fluorine (F), phosphorus (P), sulfur (S), and silicon (Si).

The carbon-based material may be a carbon nitride containing nitrogen as a heterogeneous element. As a specific example, the carbon nitride may include graphite-type carbon nitride (gC ₃ N ₄ ).

The graphite-type carbon nitride is a carbon material containing nitrogen, and is a binary compound having a two-dimensional layered structure in which hexagonal rings similar to graphene are spread in two dimensions while carbon and nitrogen are alternately arranged.

The graphite-type carbon nitride has stable allotropes of various CN structures, and has a higher nitrogen content than other nitrogen-carbon materials, so that effective reaction sites can be created, thereby increasing electron donors/acceptors. Additionally, the concentration of nitrogen improves the efficiency of mass transfer by boosting wetting with the electrolyte and provides much additional pseudo-capacitance. Furthermore, graphitic carbon nitride has the advantage of being well crystallized due to its lamellar structure to promote charge transfer, and compared to graphene, it can be easily synthesized by direct poly-condensation without complicated post-processing. there is.

By adjusting the content of these graphite-type carbon nitrides in each layer of the organic-inorganic hybrid polymer electrolyte having a multi-layer structure according to the present invention, the ionic conductivity can be improved by controlling the amorphous region affecting the ionic conductivity of each layer, , due to its structural characteristics, it acts as an anion receptor, promotes the dissociation of lithium salts, and facilitates the movement of lithium cations by combining with anions, so that all-solid-state batteries manufactured using it, especially all-solid-state lithium ion batteries, It is possible to suppress lithium dendrite growth while improving performance.

According to one embodiment of the present invention, the content of the inorganic particles included may gradually increase from the Nth electrolyte layer to the first electrolyte layer or from the first electrolyte layer to the Nth electrolyte layer. Specifically, the The content of the inorganic particles included may gradually increase from the Nth electrolyte layer to the first electrolyte layer.

According to one embodiment of the present invention, the content difference of the inorganic particles between the N-th electrolyte layer and the N-1th electrolyte layer is 3% to 10% by weight, 4% to 8% by weight, or 4% to 6% by weight. weight percent. By adjusting the content difference of the inorganic particles between the electrolyte layers within this range, the performance of the all-solid-state battery can be improved and the growth of lithium dendrite can be effectively suppressed.

According to one embodiment of the present invention, each of the first to Nth electrolyte layers may further include a lithium salt.

The lithium salt is dissociated into lithium ions and can freely move by penetrating into the first to Nth electrolyte layers. At this time, as a source of lithium ions, it enables the operation of a basic lithium battery, and as such a lithium salt, any one commonly used in a lithium secondary battery can be used without limitation.

The lithium salt is an ionizable lithium salt and can be expressed as Li ⁺ X ^- . The anion of the lithium salt is not limited thereto, but for example, F ^- , Cl ^- , Br ^- , I ^- , NO ₃ ^- , N(CN) ₂ ^- , BF ₄ ^- , ClO ₄ ^- , PF ₆ ^- , ( CF3) ₂ PF ₄ ^- , (CF ₃ ) ₃ PF ₃ ^- , (CF ₃ ) ₄ PF ₂ ^- , (CF ₃ ) ₅ PF ^- , (CF ₃ ) ₆ P ^- , CF ₃ SO ₃ ^- , CF ₃ CF ₂ SO ₃ ^- , (CF ₃ SO ₂ ) ₂ N ^- , (F _S O ₂ ) ₂ N ^- , CF ₃ CF ₂ (CF ₃ ) ₂ CO ^- , (CF ₃ SO ₂ ) ₂ CH ^- , (SF ₅ ) ₃ C ^- , (CF ₃ SO ₂ ) ₃ C ^- , CF ₃ (CF ₂ ) ₇ SO ₃ ^- , CF ₃ CO ₂ ^- , CH ₃ CO ₂ ^- , SCN ^- and (CF ₃ CF ₂ SO ₂ ) ₂ N ^- may include at least one selected from the group consisting of.

As a specific example, the lithium salt may be lithium bis(trifluoromethanesulfonyl)imide ((CF ₃ SO ₂ ) ₂ NLi, LiTFSI).

The amount of the lithium salt may be, for example, 1 part by weight to 40 parts by weight based on 100 parts by weight of the entire polymer matrix of each of the first to Nth electrolyte layers. Within this range, the ionic conductivity of each electrolyte layer is sufficiently secured to improve the charge/discharge capacity and efficiency of the all-solid-state battery.

In another embodiment of the present invention, the polymer matrix includes Poly (ethylene glycol) dimethyl ether (PEGDME), and the lithium salt is lithium bis (trifluoromethanesulfonyl) imide (Lithium It may include bis(trifluoromethane sulfonyl)imide, LiTFSI).

According to one embodiment of the present invention, each of the first to Nth electrolyte layers may further include a crosslinking agent.

The crosslinking agent is not particularly limited as long as it is a crosslinking agent commonly used in the preparation of solid electrolytes, but may include, for example, bisphenol A ethoxylate diacrylate.

According to one embodiment of the present invention, each of the first to Nth electrolyte layers may further include an initiator.

The initiator is not particularly limited as long as it is an initiator commonly used in the preparation of solid electrolytes, but a peroxide-based polymerization initiator may be used, and the peroxide-based polymerization initiator is, for example, tert-butyl peroxyneodecanoe yate (tert-butyl peroxyneodecanoate, TBND); tert-butyl peroxypivalate (TBPP), tert-butyl peroxy-2-ethylhexanoate (TBPO) and tert-butyl phenoxy-3,5 At least one selected from the group consisting of ,5-trimethylhexanoate (tert-butyl peroxy-3,5,5-trimethylhexanoate, TBPIN) may be included.

In one embodiment of the present invention, the initiator may be tert-butyl peroxypivalate (TBPP).

According to one embodiment of the present invention, the electrolyte layer having a high inorganic particle content among the first electrolyte layer or the Nth electrolyte layer may further include a liquid electrolyte.

The liquid electrolyte may use a material used as an electrolyte of a conventional lithium ion battery. For example, the liquid electrolyte may include a salt and a solvent, and may include an additive if necessary. The salt may be a passage through which lithium ions may pass, the solvent may be an organic liquid used to dissolve the salt, and the additive may be a material added in a small amount for a specific purpose. The liquid electrolyte including this allows only ions to move to the electrode and prevents electrons from passing through. Depending on the type, the movement and speed of lithium ions can be controlled.

The salt may include any one or more of the above-mentioned lithium salts.

The solvent may be a non-aqueous solvent, and the non-aqueous solvent may be, for example, propylene carbonate (PC), ethylene carbonate (EC), vinylene carbonate (VC), diethyl carbonate ( DEC), dimethyl carbonate (DMC), methyl ethyl carbonate (MEC), ethyl methyl carbonate (EMC), tetrahydrofuran (THF), 2-methyltetrahydrofuran (2MeTHF), dioxolane (DOX ), dimethoxyethane (DME), diethoxyethane (DEE), γ-butyrolactone (GBL), acetonitrile (AN), and at least one selected from the group consisting of sulfolane.

Among the first electrolyte layer or the N-th electrolyte layer, the electrolyte layer having a high inorganic particle content includes the liquid electrolyte in an amount of 5 to 30, 8 to 20, or 10 to 15 parts by weight based on 100 parts by weight of the entire polymer matrix included in the layer. can do. Within this range, dispersibility can be improved when preparing an electrolyte layer by using a minimum amount of liquid electrolyte, and the organic-inorganic hybrid polymer electrolyte according to the present invention can be applied to an all-solid-state battery.

According to one embodiment of the present invention, the organic-inorganic hybrid polymer electrolyte may be a solid electrolyte.

In general, solid electrolytes are largely classified into ceramic solid electrolytes and polymer solid electrolytes, and ceramic solid electrolytes are further classified into sulfide-based solid electrolytes and oxide-based solid electrolytes.

The sulfide-based solid electrolyte is vulnerable to humidity and generates gases such as H ₂ S (hydrogen sulfide), but has advantages such as uniform ion conductivity and temperature stability, and is being developed most actively among solid electrolytes.

The oxide-based solid electrolyte has excellent strength and high stability, but has low ionic conductivity and requires a high-temperature heat treatment process, resulting in poor production easiness.

In addition, polymer solid electrolytes are easy to produce and have high safety, but have low ionic conductivity and poor battery output.

Therefore, in the present invention, in preparing a polymer solid electrolyte with excellent productivity and safety, the performance of the battery can be improved by preparing an organic-inorganic hybrid polymer electrolyte having a multilayer structure in which the components of the inorganic particles are controlled.

According to one embodiment of the present invention, the total thickness of the organic-inorganic hybrid polymer electrolyte may be 100 μm to 500 μm, 150 μm to 500 μm, or 200 μm to 500 μm. Within the above range, the physical strength and shape stability of the organic-inorganic hybrid polymer electrolyte may be excellent and the ionic conductivity may be improved.

In the organic-inorganic hybrid polymer electrolyte, the thickness of each of the first to N-th electrolyte layers may be the same as or different from each other.

As an example, the thickness may decrease from the first electrolyte layer to the Nth electrolyte layer or from the Nth electrolyte layer to the first electrolyte layer. As a specific example, the thickness may decrease from the Nth electrolyte layer to the first electrolyte layer.

According to one embodiment of the present invention, when N is 2, the organic-inorganic hybrid polymer electrolyte may include a first electrolyte layer and a second electrolyte layer formed on one surface of the first electrolyte layer, and the first electrolyte The amount of inorganic particles included in the layer may be higher than that of the second electrolyte layer.

The first electrolyte layer and the second electrolyte layer may be solid polymer electrolytes.

The content of the polymer matrix included in each of the first electrolyte layer and the second electrolyte layer may be the same.

Inorganic particles included in each of the first electrolyte layer and the second electrolyte layer may be graphite-type carbon nitride.

The content of the inorganic particles included in the first electrolyte layer is 5 to 15 parts by weight, 7 to 13 parts by weight, or 9 to 11 parts by weight based on 100 parts by weight of the entire polymer matrix included in the first electrolyte layer. It may be part by weight.

The content of the inorganic particles included in the second electrolyte layer is 1.5 parts by weight to 6 parts by weight, 3 parts by weight to 6 parts by weight, or 5 parts by weight to 5.5 parts by weight based on 100 parts by weight of the total polymer matrix included in the second electrolyte layer. It may be part by weight.

The organic-inorganic hybrid polymer electrolyte in which the content of the inorganic particles in the first electrolyte layer and the second electrolyte layer is adjusted within the above range can be applied to an all-solid-state battery in a solid state, and when used in an all-solid-state battery, the ion conductivity It is possible to improve the performance of the battery and at the same time to improve the effect of inhibiting the growth of lithium dendrites.

According to one embodiment of the present invention, the first electrolyte layer may further include a liquid electrolyte. The amount of the liquid electrolyte included in the first electrolyte layer may be 5 to 30, 8 to 20, or 10 to 15 parts by weight based on 100 parts by weight of the entire polymer matrix included in the first electrolyte layer. In this case, when preparing the first electrolyte layer, it is prepared in a solid phase, but dispersibility is improved, and the organic-inorganic hybrid polymer electrolyte according to the present invention can be applied to an all-solid-state battery.

The total thickness of the first electrolyte layer and the second electrolyte layer may be 100 μm to 500 μm. Specifically, when the total thickness of the polymer electrolyte layer exceeds 500 μm, resistance may increase, resulting in degradation of battery performance.

At this time, the thickness ratio of the first electrolyte layer and the thickness of the second electrolyte layer may be 1:9 to 4:6. By forming the first electrolyte layer and the second electrolyte layer at a thickness ratio within the above range, deterioration in battery performance due to an increase in resistance due to the inorganic particles may be prevented and lithium dendrite growth may be suppressed. Specifically, when the thickness of the first electrolyte layer is thicker than the thickness of the second electrolyte layer, the resistance increases due to the inorganic particles, thereby reducing the performance of the battery, and when the thickness of the first electrolyte layer is too thin, dendrite growth It is difficult to exert an inhibitory effect.

According to the present invention, curing the first to Nth polymer electrolyte precursor compositions to prepare a polymer electrolyte in which the first to Nth electrolyte layers are sequentially stacked, wherein the first polymer electrolyte precursor The composition to the Nth polymer electrolyte precursor composition each include a polymer matrix and inorganic particles, and the first polymer electrolyte precursor composition to the Nth polymer electrolyte precursor composition or the Nth polymer electrolyte precursor composition to the first polymer electrolyte precursor composition proceeds from the first polymer electrolyte precursor composition to the first polymer electrolyte precursor composition. Provided is a method for preparing an organic-inorganic hybrid polymer electrolyte having a multilayer structure in which the content of inorganic particles is controlled according to the present invention, in which the content of inorganic particles is increased.

In one embodiment of the present invention, the first to Nth polymer electrolyte precursor compositions may each include a polymer matrix and inorganic particles. A detailed description of the type, content, etc. of the polymer matrix and inorganic particles may be the same as described above.

In one embodiment of the present invention, each of the first to Nth polymer electrolyte precursor compositions may further include at least one of a lithium salt, a crosslinking agent, and an initiator. Specific descriptions regarding the type, content, etc. of the lithium salt, crosslinking agent, and initiator may be the same as those described above.

According to one embodiment of the present invention, the electrolyte layer having a high inorganic particle content among the first electrolyte layer or the Nth electrolyte layer may further include a liquid electrolyte. A detailed description of the type and content of the liquid electrolyte may be the same as described above.

In one embodiment of the present invention, the polymer electrolyte may be prepared by mixing the polymer matrix, the lithium salt, the crosslinking agent, and the initiator, adding the inorganic particles before thermal curing, and then thermally curing. It is not.

In one embodiment of the present invention, when preparing the first to Nth electrolyte layers by curing the first to Nth polymer electrolyte precursor compositions, the thickness of each electrolyte layer may be adjusted.

In one embodiment of the present invention, preparing a first electrolyte layer by curing the first polymer electrolyte precursor composition; and preparing a second electrolyte layer by curing a second polymer electrolyte precursor composition on one surface of the first electrolyte layer, wherein the first polymer electrolyte precursor composition and the second polymer electrolyte precursor composition are respectively composed of a polymer matrix and an inorganic matrix. The inorganic particles according to the present invention include particles, and the content of the inorganic particles increases from the first polymer electrolyte precursor composition to the second polymer electrolyte precursor composition or from the second polymer electrolyte precursor composition to the first polymer electrolyte precursor composition. It is possible to provide a method for preparing an organic-inorganic hybrid polymer electrolyte having a multilayer structure in which the content of is controlled.

The amount of the polymer matrix included in each of the first polymer electrolyte precursor composition and the second polymer electrolyte precursor composition may be the same.

The inorganic particles included in each of the first polymer electrolyte precursor composition and the second polymer electrolyte precursor composition may be graphite-type carbon nitride.

The content of the inorganic particles included in the first polymer electrolyte precursor composition is 5 to 15 parts by weight, 7 to 13 parts by weight, or 9 parts by weight based on 100 parts by weight of the entire polymer matrix included in the first polymer electrolyte precursor composition. part to 11 parts by weight.

The content of the inorganic particles included in the second polymer electrolyte precursor composition is 1.5 parts by weight to 6 parts by weight, 3 parts by weight to 6 parts by weight, or 5 parts by weight based on 100 parts by weight of the entire polymer matrix included in the second polymer electrolyte precursor composition. It may be parts by weight to 5.5 parts by weight.

In the case of using an organic-inorganic hybrid polymer electrolyte in which the content of inorganic particles included in the first polymer electrolyte precursor composition and the second polymer electrolyte precursor composition is adjusted within the above range for an all-solid-state battery, ion conductivity is improved to improve battery performance and At the same time, the effect of inhibiting lithium dendrite growth can be improved.

According to one embodiment of the present invention, the first polymer electrolyte precursor composition may further include a liquid electrolyte. By adding a liquid electrolyte to the first polymer electrolyte precursor composition, the dispersibility of the first polymer electrolyte precursor composition can be improved, and the organic-inorganic hybrid polymer electrolyte according to the present invention can be applied to an all-solid-state battery. there is.

According to the present invention, a negative electrode; anode; and an organic-inorganic hybrid polymer electrolyte having a multi-layered structure in which the amount of inorganic particles according to the present invention is controlled and formed between the negative electrode and the positive electrode.

In one embodiment of the present invention, the negative electrode may use lithium metal (Li metal) alone or a negative electrode active material laminated on a negative electrode current collector.

The anode active material may include at least one selected from the group consisting of lithium metal, lithium alloy, lithium metal composite oxide, and lithium-containing titanium composite oxide (LTO). In this case, the lithium alloy may include an alloy made of lithium and at least one metal selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Al, and Sn. In addition, the lithium metal composite oxide may be any one metal (Me) oxide (MeO _x ) selected from the group consisting of lithium and Si, Sn, Zn, Mg, Cd, Ce, Ni, and Fe, and for example, Li _x Fe ₂ O ₃ (0<x≤1) or Li _x WO ₂ (0<x≤1).

In addition, the negative electrode active material is Sn _x Me _1-x Me' _y O _z (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, Groups 1, 2, and 3 elements of the periodic table , halogen; 0<x≤1;1≤y≤3;1≤z≤8); SnO, SnO ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ , GeO, GeO ₂ , Bi ₂ O ₃ , Bi ₂ O ₄ and Oxides such as Bi ₂ O ₅ may be used, and carbon-based negative active materials such as crystalline carbon, amorphous carbon, or carbon composites may be used alone or in combination of two or more.

In addition, the anode current collector is not particularly limited as long as it has conductivity without causing chemical change in the all-solid-state battery, and for example, the surface of copper, stainless steel, aluminum, nickel, titanium, fired carbon, copper or stainless steel. For the surface treatment with carbon, nickel, titanium, silver, etc., an aluminum-cadmium alloy or the like may be used.

In addition, various forms such as a film, a sheet, a foil, a net, a porous material, a foam, a nonwoven fabric, etc. having fine irregularities formed on a surface thereof may be used as the anode current collector.

In one embodiment of the present invention, an all-solid lithium metal battery may be manufactured by using only lithium metal as an anode active material in a copper current collector for the anode. When lithium metal is used as the negative electrode, lithium ions can be discharged on a large scale and thus the performance of the battery can be dramatically improved. However, in the prior art, it has been difficult to apply due to problems caused by the generation of lithium dendrites.

However, even when lithium metal is used as the negative electrode, when the organic-inorganic hybrid polymer electrolyte having a multi-layered structure in which the content of inorganic particles is controlled according to the present invention is applied, battery performance is improved due to lithium metal and at the same time suppression of lithium dendrite growth through The effect of improving safety can be implemented simultaneously.

In one embodiment of the present invention, an electrolyte layer having a high inorganic particle content among the first to Nth electrolyte layers may be positioned adjacent to the negative electrode. In this case, the content of the inorganic particles may increase gradually from the Nth electrolyte layer to the first electrolyte layer.

As such, by placing the electrolyte layer having a high content of inorganic particles adjacent to the negative electrode, it is possible to uniformly control the flux of lithium ions through gC ₃ N ₄ to suppress the growth of lithium dendrites in the negative electrode. Conversely, , The electrolyte layer away from the negative electrode can realize the effect of increasing ionic conductivity and promoting dissociation of lithium salt due to the content of inorganic particles.

In one embodiment of the present invention, taking the case where N is 2 as an example, the organic-inorganic hybrid polymer electrolyte includes a first electrolyte layer and a second electrolyte layer formed on one surface of the first electrolyte layer, An amount of inorganic particles included in the first electrolyte layer may be higher than an amount of inorganic particles included in the second electrolyte layer. In this case, the organic-inorganic hybrid polymer electrolyte may be positioned such that the first electrolyte layer is adjacent to the negative electrode.

As described above, the content of the inorganic particles included in the first electrolyte layer adjacent to the negative electrode is 5 to 15 parts by weight, 7 to 7 parts by weight based on 100 parts by weight of the entire polymer matrix included in the first electrolyte layer. It may be 13 parts by weight or 9 parts by weight to 11 parts by weight, and there is a problem that the dendrite growth inhibitory effect decreases when the lower limit of the range is exceeded, and the electrolyte layer is not prepared when the upper limit of the range is exceeded.

As described above, the content of the inorganic particles included in the second electrolyte layer spaced apart from the negative electrode compared to the first electrolyte layer is 1.5 parts by weight to 6 parts by weight based on the total 100 parts by weight of the polymer matrix included in the second electrolyte layer. It may be 3 parts by weight to 6 parts by weight or 5 parts by weight to 5.5 parts by weight. If the lower limit of the range is exceeded, there is a problem in that the ion conductivity decreases, and if the upper limit of the range is exceeded, a solid polymer electrolyte is not prepared. There is a problem not

In one embodiment of the present invention, the anode positioned opposite to the cathode with the organic-inorganic hybrid polymer electrolyte according to the present invention interposed therebetween is not particularly limited and may be a material used in a known all-solid-state battery.

In one embodiment of the present invention, the positive electrode may have a structure in which a positive electrode active material layer is formed on one surface of a positive electrode current collector, but is not limited thereto.

The positive current collector is not particularly limited as long as it does not cause chemical change in the battery and has high conductivity. For example, stainless steel, aluminum, nickel, titanium, fired carbon, or carbon on the surface of aluminum or stainless steel, A surface treated with nickel, titanium, silver, or the like may be used.

The positive electrode active material layer may include a positive electrode active material and a binder, and may further include an additive such as a conductive material, if necessary.

The cathode active material may vary depending on the use of the lithium secondary battery, and may include LiNi _0.8-x Co _0.2 Al _x O ₂ , LiCo _x Mn _y O ₂ , LiNi _x Co _y O ₂ , LiNi _x Mn _y O ₂ , LiNi _x Co lithium transition metal oxides such as _y Mn _z O ₂ , LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiFePO ₄ , LiCoPO ₄ , LiMnPO ₄ and Li ₄ Ti ₅ O ₁₂ ; Cu ₂ Mo ₆ S ₈ , Chalcogenides such as FeS, CoS and MiS, oxides, sulfides or halides such as scandium, ruthenium, titanium, vanadium, molybdenum, chromium, manganese, iron, cobalt, nickel, copper and zinc It may be used, and more specifically, TiS ₂ , ZrS ₂ , RuO ₂ , Co ₃ O ₄ , Mo ₆ S ₈ , V ₂ O ₅ and the like may be used, but are not limited thereto. As a specific example, the cathode active material may include a lithium transition metal oxide including nickel, cobalt, and manganese.

The binder included in the positive electrode is not particularly limited, and fluorine-containing binders such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE) may be used. The content of the binder is not particularly limited as long as it can fix the positive electrode active material, and may be in the range of 0 to 10% by weight with respect to the entire positive electrode.

The conductive material is not particularly limited as long as it can improve the conductivity of the anode, and may include nickel powder, cobalt oxide, titanium oxide, carbon, and the like. The carbon may include at least one selected from the group consisting of ketjen black, acetylene black, furnace black, graphite, carbon fiber, and fullerene.

Hereinafter, examples will be described in detail to explain the present invention in detail. However, the embodiments according to the present invention can be modified in many different forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

Example

Example 1

1. Inorganic particle preparation

1 g of melamine was added to 40 mL of dimethyl sulfoxide (DMSO) and stirred to prepare a first solution, and 1 g of cyanuric acid was added to 20 mL of dimethyl sulfoxide (DMSO) It was added to mL and stirred to prepare a second solution, and the first solution was added to the second solution and reacted at 0 ° C to prepare a mixed solution.

The mixed solution was left for 2 hours in a static state, centrifuged, and washed three times with deionized water and ethanol.

Then, the white precipitate was dried at 60 °C for 24 hours, and heat-treated while heating at 550 °C for 4 hours at 2.3 °C/min under a nitrogen atmosphere to prepare gC ₃ N ₄ particles.

2. Polymer electrolyte preparation

<Preparation of the first electrolyte layer>

1.5 g of polyethylene glycol dimethyl ether (PEGDME) as the polymer matrix, 0.2699 g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as the lithium salt, and bisphenol A as the crosslinking agent. 0.19 g of bisphenol A ethoxylate diacrylate, 0.01 g of tert-butyl peroxypivalate (t-BPP) as an initiator, and 1 M LiPF6 in EC/DMC (1: 1) A polymer electrolyte was prepared by thermal curing at 100 °C using 0.2 mL of + 10 wt% FEC + 2 wt% VC. At this time, before thermal curing, the first electrolyte layer was prepared by adding the prepared gC ₃ N ₄ particles in an amount of 10 parts by weight relative to 100 parts by weight of the polymer matrix, and had a thickness of 100 μm.

<Preparation of the second electrolyte layer>

On one side of the prepared first electrolyte layer, 1.5 g of polyethylene glycol dimethyl ether (PEGDME) as a polymer matrix and lithium bis (trifluoromethanesulfonyl) imide as lithium salt , LiTFSI) 0.2699 g, bisphenol A ethoxylate diacrylate 0.19 g as a crosslinking agent, and tert-butyl peroxypivalate (t-BPP) 0.01 g as an initiator. A polymer electrolyte was prepared by thermal curing at °C. At this time, before thermal curing, a second electrolyte layer was prepared on one side of the first electrolyte layer by adding the prepared gC ₃ N ₄ particles in an amount of 5 parts by weight relative to 100 parts by weight of the polymer matrix, and had a thickness of 300 μm.

3. All-solid-state battery manufacturing

As shown in FIG. 1, a gasket 40 formed of PP having a ring structure in a main body 50 including a receiving part therein, a negative electrode 10 having a lithium metal layer formed on a copper foil, the polymer electrolyte 30 prepared above, and NCM811 An all-solid-state battery was prepared by placing a positive electrode 20 including a and sealing with a cap 60. At this time, among the first electrolyte layer 31 and the second electrolyte layer 32 of the polymer electrolyte, the first electrolyte layer 31 was positioned adjacent to the cathode, and a photograph of the polymer electrolyte is shown in FIG. 2 below. .

Example 2

In Example 1, except that the polymer electrolyte prepared by adjusting the content of the gC ₃ N ₄ particles to 8 parts by weight instead of 10 parts by weight when preparing the first electrolyte layer, and appropriately adjusting the content of the liquid electrolyte accordingly, was used. An all-solid-state battery was manufactured in the same manner as in Example 1.

Example 3

In Example 1, except that the polymer electrolyte prepared by adjusting the content of the gC ₃ N ₄ particles to 12 parts by weight instead of 10 parts by weight when preparing the first electrolyte layer and appropriately adjusting the content of the liquid electrolyte accordingly was used. An all-solid-state battery was manufactured in the same manner as in Example 1.

Example 4

In Example 1, except that the polymer electrolyte prepared by adjusting the content of the gC ₃ N ₄ particles to 2 parts by weight instead of 10 parts by weight when preparing the first electrolyte layer, and appropriately adjusting the content of the liquid electrolyte accordingly, was used. An all-solid-state battery was manufactured in the same manner as in Example 1.

Example 5

In Example 1, except that the polymer electrolyte prepared by adjusting the content of the gC ₃ N ₄ particles to 15 parts by weight instead of 10 parts by weight when preparing the first electrolyte layer, and appropriately adjusting the content of the liquid electrolyte accordingly, was used. An all-solid-state battery was manufactured in the same manner as in Example 1.

In this case, although the content of gC ₃ N ₄ particles in the electrolyte layer adjacent to the anode was high, dendrite growth was suppressed, but the performance of the battery deteriorated due to high resistance.

comparative example

Comparative Example 1

In Example 1, an all-solid-state battery was manufactured in the same manner as in Example 1, except that a polymer electrolyte consisting only of the first electrolyte layer was used without preparing the second electrolyte layer.

In this case, the effect of inhibiting dendrite growth was similar to that of the above example, but there was a problem in that battery performance deteriorated due to high resistance.

Comparative Example 2

In Example 1, when preparing the polymer electrolyte, 1.5 g of polyethylene glycol dimethyl ether (PEGDME) as a polymer matrix between the first electrolyte layer and the second electrolyte layer, lithium bis (trifluoromethane) as a lithium salt 0.2699 g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), 0.19 g of bisphenol A ethoxylate diacrylate as a crosslinking agent, tert-butyl peroxypivalate as an initiator peroxypivalate, t-BPP) 0.01 g, 0.2 mL of 1 M LiPF6 in EC/DMC (1:1) + 10 wt% FEC + 2 wt% VC as a liquid electrolyte, and thermally cured at 100 ° C to prepare a polymer electrolyte , The same method as in Example 1, except that a third electrolyte layer having a thickness of 200 μm was further included by adding the prepared gC ₃ N ₄ particles in an amount of 15 parts by weight relative to 100 parts by weight of the polymer matrix before thermal curing. An all-solid-state battery was prepared.

In this case, not only the performance of the battery deteriorates as the total thickness of the polymer electrolyte increases and the resistance increases, but also the overall battery performance decreases because the ratio of the layer adjacent to the anode that determines the ionic conductivity decreases.

Experimental example

Experimental Example 1

In each case of Examples 1 to 4, SEM pictures after the 10th charge of the all-solid-state battery are shown in FIGS. 3 to 6 in order to confirm the degree of lithium dendrite growth. At this time, the current density was 0.1 mA/cm ² , the capacity was 1.0 mAh/cm ² , and an SEM was measured to observe an image of lithium electrodeposited on the copper surface as the negative electrode during the 10th charge.

Referring to FIGS. 3 to 6 , in the case of Examples 1 to 4, it can be confirmed that lithium dendrite growth is suppressed through SEM images of the copper surface.

Referring to FIG. 6, it can be confirmed that dendrites grew due to non-uniform electrodeposition of lithium compared to FIGS. It was confirmed that the effect was low.

Experimental Example 2

In each of Examples 1 to 5 and Comparative Examples 1 to 2, NCM811 was used as an anode and lithium metal was used as a cathode, and then a current was applied at a current density of 0.1C (20 mA/g). When the specific capacity was measured as shown in FIGS. 7 to 13 and the discharge capacity at this time was measured, the results are shown in Table 1 below.

Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 discharge capacity
(mAh/g) 146 145 140 146 101 95 97

Referring to Table 1, Example 5 having a high content of gC ₃ N ₄ particles in the first electrolyte layer, Comparative Example 1 in which only the first electrolyte layer was formed as a polymer electrolyte, and between the first electrolyte layer and the second electrolyte layer In the case of Comparative Example 2 further comprising a third electrolyte layer including a high content of gC ₃ N ₄ particles, the discharge capacity was reduced compared to Examples 1 to 4, and it could be confirmed that the performance of the battery was deteriorated through this. there was.

So far, the organic-inorganic hybrid polymer electrolyte according to an embodiment of the present invention, its manufacturing method, and specific examples of an all-solid-state lithium secondary battery including the same have been described, but various implementations are carried out within the limits not departing from the scope of the present invention. It is obvious that variations are possible.

Therefore, the scope of the present invention should not be limited to the described embodiments and should not be defined, and should be defined by not only the claims to be described later, but also those equivalent to these claims.

That is, it should be understood that the above-described embodiments are illustrative in all respects and not restrictive, and the scope of the present invention is indicated by the claims to be described later rather than the detailed description, and the meaning and scope of the claims and All changes or modified forms derived from the equivalent concept should be construed as being included in the scope of the present invention.

10: cathode
20: anode
30: polymer electrolyte
31: first electrolyte layer
32: second electrolyte layer
40: gasket
50: body
60: cap

Claims (14)

It includes sequentially stacked first electrolyte layers to Nth electrolyte layers,
The first to Nth electrolyte layers each include a polymer matrix and inorganic particles,
The content of the inorganic particles increases from the first electrolyte layer to the Nth electrolyte layer or from the Nth electrolyte layer to the first electrolyte layer,
An organic-inorganic hybrid polymer electrolyte with a multi-layer structure in which the content of inorganic particles is controlled.
According to claim 1,
Characterized in that the inorganic particles are carbon-based materials,
An organic-inorganic hybrid polymer electrolyte with a multi-layer structure in which the content of inorganic particles is controlled.
According to claim 2,
Characterized in that the inorganic particles are carbon nitrides,
An organic-inorganic hybrid polymer electrolyte with a multi-layer structure in which the content of inorganic particles is controlled.
According to claim 1,
Characterized in that the N is 2 to 5,
An organic-inorganic hybrid polymer electrolyte with a multi-layer structure in which the content of inorganic particles is controlled.
According to claim 1,
Characterized in that the content of the inorganic particles included in the Nth electrolyte layer increases toward the first electrolyte layer,
An organic-inorganic hybrid polymer electrolyte with a multi-layer structure in which the content of inorganic particles is controlled.
According to claim 1,
Characterized in that the difference in the content of inorganic particles between the Nth electrolyte layer and the N-1th electrolyte layer is 3% to 10% by weight,
An organic-inorganic hybrid polymer electrolyte with a multi-layer structure in which the content of inorganic particles is controlled.
According to claim 1,
The organic-inorganic hybrid polymer electrolyte consists of a first electrolyte layer and a second electrolyte layer formed on one surface of the first electrolyte layer,
Characterized in that the content of inorganic particles included in the first electrolyte layer is higher than the content of inorganic particles included in the second electrolyte layer,
An organic-inorganic hybrid polymer electrolyte with a multi-layer structure in which the content of inorganic particles is controlled.
According to claim 7,
The content of the inorganic particles included in the first electrolyte layer is 5 parts by weight to 15 parts by weight based on the total 100 parts by weight of the polymer matrix included in the first electrolyte layer,
Characterized in that the content of the inorganic particles included in the second electrolyte layer is 1.5 parts by weight to 6 parts by weight based on the total 100 parts by weight of the polymer matrix included in the second electrolyte layer.
An organic-inorganic hybrid polymer electrolyte with a multi-layer structure in which the content of inorganic particles is controlled.
According to claim 7,
Characterized in that the first electrolyte layer further comprises a liquid electrolyte,
An organic-inorganic hybrid polymer electrolyte with a multi-layer structure in which the content of inorganic particles is controlled.
According to claim 1,
Characterized in that the total thickness of the organic-inorganic hybrid polymer electrolyte is 100 μm to 500 μm,
An organic-inorganic hybrid polymer electrolyte with a multi-layer structure in which the content of inorganic particles is controlled.
Curing the first to Nth polymer electrolyte precursor compositions to prepare a polymer electrolyte in which the first to Nth electrolyte layers are sequentially stacked;
The first to Nth polymer electrolyte precursor compositions each include a polymer matrix and inorganic particles,
The content of the inorganic particles increases from the first polymer electrolyte precursor composition to the Nth polymer electrolyte precursor composition or from the Nth polymer electrolyte precursor composition to the first polymer electrolyte precursor composition,
A method for preparing an organic-inorganic hybrid polymer electrolyte having a multilayer structure in which the content of inorganic particles according to claim 1 is controlled.
cathode;
anode; and
Including the organic-inorganic hybrid polymer electrolyte according to claim 1 formed between the negative electrode and the positive electrode,
An all-solid-state battery comprising an organic-inorganic hybrid polymer electrolyte having a multilayer structure in which the content of inorganic particles is controlled.
According to claim 12,
Characterized in that the electrolyte layer having a high content of inorganic particles among the first to Nth electrolyte layers is positioned adjacent to the cathode,
An all-solid-state battery comprising an organic-inorganic hybrid polymer electrolyte having a multilayer structure in which the content of inorganic particles is controlled.
According to claim 12,
Characterized in that the negative electrode contains lithium metal,
An all-solid-state battery comprising an organic-inorganic hybrid polymer electrolyte having a multilayer structure in which the content of inorganic particles is controlled.