CN101290983A - plate conductive structure - Google Patents

Abstract

A conductive structure of a plate comprises a bundle-type three-dimensional electronic channel structure formed of one or more first conductive materials capable of providing an electronic conduction function; a conductive coherent three-dimensional structure which is formed by one or more second conductive materials and can provide active substance adsorption and bearing support for the tube bundle-like three-dimensional electronic channel structure; and a three-dimensional gap space structure composed of the first conductive material and the second conductive material and capable of providing an electrolyte or electrolyte ion conduction channel. The inside of a similar net-like 3D structure formed by a similar tube bundle type three-dimensional electronic channel structure and a conductive coherent three-dimensional structure can be used as an ion channel, the adhesive force of an active substance on a base material can be enhanced by the net-like structure, and the conduction channel can also promote the rapid conduction of electrons, so that the similar net-like 3D structure is used for manufacturing a battery, and the charge-discharge rate (C-rate) of the battery can be effectively improved.

Description

plate conductive structure

technical field

The present invention relates to a conductive structure of a polar plate, in particular to a conductive structure of a polar plate containing conductive additives.

Background technique

Lithium-ion secondary batteries have the advantages of high energy density, high operating voltage, and stable discharge characteristics. Therefore, countries around the world are actively researching and developing, hoping to improve battery performance and reduce costs to meet market demand. In order to improve the poor conductivity of lithium oxide plates, high conductivity materials are usually added and kneaded evenly in the lithium oxide slurry to improve the overall conductivity of lithium oxide series plates

Previous patents or papers on the use of conductive additives to improve the overall conductivity and electrical performance of the plate are mainly applied to the negative plate, such as US Patent No. 6806003, US Patent No. 2004224232, and Japanese Patent No. 41-55776 , Canadian Patent No. 2341693, and Taiwan Patent No. 232607B and other patent documents. Among them, U.S. Patent No. 6806003 and U.S. Patent No. 2004224232 disclose the use of carbon fibers and carbon flakes as conductive additives in the negative electrode, using the synergistic effect exhibited by the two to improve the polar plate pair The retention capacity of the electrolyte and the conductivity of the active body are used to increase the conductive performance of the plate and the carrying capacity of high load current. Taiwan Patent No. 232607 discloses the use of a small amount of carbon nanotubes or carbon fibers formed by high-temperature gaseous deposition to form a meso-phase graphite mixture on the negative plate to increase the conductivity of the plate. efficacy.

Japanese Patent No. 70-14582 discloses that adding carbonaceous materials to the positive electrode can reduce the battery impedance. Japanese Patent No. 2003-092105 discloses that the low-temperature discharge of the positive electrode is improved. Since the bottom of the carbon fiber is open (ends are opened), it can form a uniform pore shape (uniform pore shape), so it can reduce the impedance during low-temperature testing. and improve performance. Both Japanese Patent No. 2004-022177 and Japanese Patent No. 70-14582 disclose the addition of carbonaceous materials to improve electrical conductivity. However, Japanese Patent No. 2004-022177 discloses that all conductive carbonaceous materials should account for 10% of all powders in the positive electrode, and flake graphite must be present in the conductive carbonaceous materials. Japanese Patent No. 2006-127823 discloses that the conductive carbonaceous material includes carbon fibers and carbon sheets, but after mixing, the slurry including the conductive carbonaceous material and the adhesive must pass through a magnetic field provided by an external force during coating, so that The direction of all conductive carbonaceous materials is perpendicular to the surface of the substrate, and then the distribution of the liquid slurry on the substrate is fixed by drying.

The above-mentioned patent documents do not disclose the use of graphite with flake structure and carbon fiber tube with tubular structure to mix and knead with lithium-based oxides and structure design to make the conductive structure of the electrode plate, so as to improve the charge-discharge rate of the battery.

Contents of the invention

In view of the above problems, the main purpose of the present invention is to provide a high-efficiency plate conductive structure.

Another object of the present invention is to provide a plate conductive structure that can increase the charging and discharging rate of the battery.

In order to achieve the above and other purposes, the present invention provides a plate conductive structure, which includes a tube bundle type three-dimensional electronic channel structure that can provide electron conduction function formed by one or more first conductive materials; The conductive material forms a conductive and coherent three-dimensional structure that can provide active material adsorption and support a tube-like three-dimensional electronic channel structure; and a three-dimensional structure composed of the first conductive material and the second conductive material that can provide electrolyte or electrolyte ion conduction channels Interstitial space structure. The network-like 3D structure formed by the tube-like three-dimensional electronic channel structure and the conductive coherent three-dimensional structure can be used as an ion channel inside, and the network structure itself can enhance the adhesion of the active material on the substrate , and the conduction channel can also promote the rapid conduction of electrons, which can be used to make batteries, which can effectively improve the charge and discharge rate (C-rate) of the battery.

Description of drawings

Fig. 1 shows the rheological curve of the slurry of comparative example 1 and embodiment 1 of the present invention;

Fig. 2 shows the electron microscope structure of the polar plate structure control sample of Comparative Example 1;

Fig. 3 shows the electron microscope structure of the electrode plate structure sample of embodiment 1 of the present invention;

FIG. 4A is a top view electron microscope structure showing a pole plate structure sample according to Example 2 of the present invention;

Fig. 4B is the upward electron microscope structure showing the polar plate structure sample of Example 2 of the present invention;

Fig. 4C is a cross-sectional electron microscope structure junction showing the polar plate structure sample of Example 2 of the present invention;

FIG. 5A is a top view electron microscope structure showing the pole plate structure sample of Example 3 of the present invention;

FIG. 5B is an upward electron microscope structure showing the polar plate structure sample of Example 3 of the present invention;

Fig. 5C is a cross-sectional electron microscope structure junction showing the polar plate structure sample of Example 3 of the present invention;

FIG. 6A is a top view electron microscope structure showing a pole plate structure sample according to Example 4 of the present invention;

FIG. 6B is an upward electron microscope structure showing the polar plate structure sample of Example 4 of the present invention;

Figure 6C is a cross-sectional electron microscope structure junction showing the electrode plate structure sample of Example 4 of the present invention; and

7 is a graph showing the high-current discharge capacity performance of batteries assembled using the plate structure samples of Example 1 and Comparative Example 1 as positive plates.

Implementation

The pole plate conductive structure of the present invention is mainly applied to the positive pole plate of a lithium battery. Generally speaking, the positive plate of a lithium battery mainly includes positive active materials, such as lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMn2O4), lithium nickel oxide (LiNiO2), lithium iron phosphate oxide (LiFePO4), or Its mixture; conductive additives, such as graphite (graphite), vapor phase growth carbon fiber (Vapor Grow Carbon Fiber, VGCF), or carbon black (carbon black); adhesives, such as polyvinylidene fluoride (Polyvinylidene Fluoride, PVDF), polyaromatic Polyarylsulfone (PAS), polytetrafluoroethylene (PTEF), etc.; and solvents, such as N-methylpyrrolidinone (NMP).

The conductive additive used in the present invention can be divided into the first type of conductive additive, that is, the tubular conductive material, strip conductive material, rod-shaped conductive material, or fibrous conductive material whose Z direction is greater than the X direction and direction Y, and the second Similar conductive additives, that is, the sheet-like conductive material, layered conductive material, or granular conductive material whose X direction and Y direction are greater than the Z direction. The present invention mainly utilizes the difference in structure and properties between the first conductive additive and the second conductive additive, and the sterically stable coordination mechanism generated, through the stacking, stacking and aggregation of heterostructures and the interaction between themselves and each other , forming a network-like three-dimensional structure with multiple functionalities. The active material is evenly rooted on the three-dimensional network structure through the adhesive to obtain a high-efficiency plate structure.

The first type of conductive additive used in the present invention can be a carbonaceous conductive material, such as carbon tube, carbon fiber, or vapor phase grown carbon fiber (Vapor Grow Carbon Fiber, VGCF), or a non-carbonaceous conductive material, such as metal, conductive Composite materials and conductive polymers, and the first type of conductive additives can be aggregated and pasted together to form a network-like three-dimensional structure, forming a tube-like three-dimensional electronic channel structure. The second type of conductive additives used in the present invention can be carbonaceous conductive materials, such as carbon black, graphite, and carbon sixty, or non-carbonaceous conductive materials, such as metals, conductive composite materials, and conductive polymers, And the second type of conductive additives can be superimposed and connected to form a three-dimensional structure, forming a conductive continuous three-dimensional structure. The interstitial space other than the tube-bundle three-dimensional electronic channel structure and the conductive coherent three-dimensional structure is the three-dimensional interstitial space structure.

In a specific example, lithium cobalt oxide and polyvinylidene fluoride are used as the active material and adhesive of the plate respectively, and the conductive material KS with a sheet structure and the conductive material VGCF with a tubular structure are used together. Mixing and blending. The conductive material VGCF with a tubular structure is distributed on the plate base material in bundles after kneading and slurrying, and at the same time, it is coated with the conductive material KS with a sheet structure, and is firmly connected with a sheet-like adhesive by a polyvinylidene fluoride adhesive. The conductive material KS with a structure and the conductive material VGCF with a tubular structure form a network-like three-dimensional structure with multiple functions. The viscosity is measured by a rheometer, and the degree of mixing is judged by the rheological curve. After vacuuming and confirming that there are no residual air bubbles in the slurry, the slurry is evenly coated on the base material of the electrode plate with a coater. Examples of the substrate include an aluminum foil substrate, an aluminum alloy foil substrate, a nickel foil substrate, a platinum foil substrate, or a copper alloy foil substrate. In this specific example, the coating speed is in the range of 0.1 to 20 meters/minute, preferably in the range of 0.1 to 10 meters/minute, more preferably in the range of 0.5 to 5 meters/minute.

The solvent is volatilized by the baking step, which can be performed at a temperature ranging from 60 to 250° C., preferably at a temperature ranging from 100 to 180° C. The active material lithium cobalt oxide is evenly rooted in the multifunctional network-like three-dimensional structure formed by the sheet-shaped conductive material KS and the tubular conductive material VGCF. After the slurry is completely dried, a rolling manufacturing method such as a round-shaft roller pressing method is used to make the structure more dense and firm, and to obtain a positive electrode plate with high performance.

Due to the relationship between structure and density, conductive material KS with sheet structure is easier to float after mixing slurry, and the floating sheet KS can form an electronic path on the surface of the plate, which is helpful for surface reaction. The VGCF, a conductive material with a tubular structure that can penetrate deep into the particle accumulation, connects particles at different accumulation levels through three-dimensional, vertical and horizontal bundles in an orderly manner, forming a vertical and horizontal electronic pathway network, which can connect the surface and the aluminum foil of the electrode plate substrate, so as to achieve the gain effect of both high electron conduction performance and high lithium-ion conversion power.

On the other hand, the existence of the conductive material VGCF with a tubular structure will form a three-dimensional obstacle to the structural space of the conductive material KS with a sheet structure, so that the sheet-like conductive material KS cannot float on the upper layer of the pole plate in a flat manner, and The ups and downs or non-planar placement of the sheet-shaped conductive material KS is caused, thereby increasing the contact area between the sheet-shaped conductive material KS and the active material lithium cobalt oxide, forming a free space in the plate structure, and improving the conversion efficiency and in-out transmission energy of lithium ions. Offers considerable help.

In contrast, the existence of the conductive material KS with a sheet structure will also form a three-dimensional obstacle to the structural space of the conductive material VGCF with a tubular structure, so that the tubular conductive material VGCF cannot be evenly and vertically inserted into the pores between the particles. It also cannot cross the surface of the particles, but is pushed into the grooves at the interface of the particles, and squeezed together to form a large bundle of tubular conductive material structures. This large bundle of conductive materials will form a three-dimensional conductive structure network with large electronic pathways, which will accelerate the electron transfer between the surface of the electrode plate and the aluminum foil substrate.

In the present invention, the conductive material additive VGCF with a tubular structure and the conductive material additive KS with a sheet structure are distributed on the surface of the aluminum substrate of the plate, interlaced with each other, and form an intricate network-like shape extending in all directions with the adhesive and the active material. Three-dimensional conductive structure. This kind of net-like three-dimensional conductive structure has small net-like pathways and large beamline channels, and the gaps in the structure can also form flow channels for ions. Therefore, applying this kind of net-like three-dimensional conductive structure to the production of electrode plates can improve both electronic and ion conductivity. Furthermore, the small reticular pathways and large beamline channels formed in the structure of the pole plate with this kind of reticular three-dimensional conductive structure will also cause small aggregations of lithium cobalt oxides, thereby forming a porous structure. This kind of porous structure can promote the passage of ions and increase the release and accumulation of capacitance.

The characteristics and functions of the present invention are further described below through specific specific examples, but they are not intended to limit the scope of the present invention.

Example

Comparative example 1

Using N-methylpyrrolidone as a solvent, 89% by weight of lithium cobalt oxide, 4% by weight of polyvinylidene fluoride, and 7% by weight of conductive material KS having a sheet structure were added. Use a rheometer to confirm the viscosity of the slurry, and the rheological curve of the slurry is shown in Figure 1. The slurry was coated onto the electrode plate substrate at a speed of 1 meter per minute, and a two-stage baking step was performed at a temperature of 110° C. and 130° C. using an oven with a total length of 3 meters. After the solvent was evaporated and completely dried, rolling was carried out to obtain a plate structure control sample 1, as shown in FIG. 2 .

Example 1

Using N-methylpyrrolidone as a solvent, add 89% by weight of lithium cobalt oxide, 4% by weight of polyvinylidene fluoride, and 7% by weight of conductive additives, including 4% by weight of Conductive material KS, and 3% by weight of conductive material VGCF having a tubular structure (100 to 200 microns in diameter and 10 to 20 microns in length). Use a rheometer to confirm the viscosity of the slurry, and the rheological curve of the slurry is shown in Figure 1. The slurry was coated onto the electrode plate substrate at a speed of 1 meter per minute, and two-stage baking steps were performed at temperatures of 110° C. and 130° C. using an oven with a total length of 3 meters. After the solvent is evaporated and completely dried, rolling is carried out to obtain a plate structure sample 1 of the present invention, as shown in FIG. 3 .

Example 2

Repeat the steps of Example 1, change the lithium cobalt oxide to 91% by weight, change polyvinylidene fluoride to 3% by weight, change the conductive material KS with sheet structure to 4% by weight, and change the conductive material with tubular structure VGCF was changed to 2% by weight. A plate structure sample 2 of the present invention was prepared, as shown in Figures 4A to 4C.

Example 3

Repeat the steps of Example 1, changing the lithium cobalt oxide to 91% by weight, changing polyvinylidene fluoride to 3% by weight, changing the conductive material KS with a sheet structure to 3% by weight, and changing the conductive material with a tubular structure VGCF was changed to 3% by weight. A plate structure sample 3 of the present invention was prepared, as shown in Figures 5A to 5C.

Example 4

Repeat the steps of Example 1, change the lithium cobalt oxide to 91% by weight, change polyvinylidene fluoride to 3% by weight, change the conductive material KS with sheet structure to 2% by weight, and change the conductive material with tubular structure VGCF was changed to 4% by weight. A plate structure sample 4 of the present invention was prepared, as shown in Figures 6A to 6C.

The electrode plate structure samples of Example 1 and Comparative Example 1 were respectively used as positive electrode plates, assembled into batteries and then measured for high-current discharge capacity performance. As shown in Figure 7, the battery assembled with the positive plate with increased VGCF addition has a higher high-current discharge capacity.

The above examples and comparative examples are only used to illustrate the principles and effects of the present invention, but not to limit the present invention. Anyone skilled in the art can make modifications and changes to the above examples without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be listed in the scope of patent application described later.

Claims (20)

1. conductive structures of polar plate comprises:

Formed electrical conductivity function and so on tube bank type three-dimensional electronic channel architecture can be provided by one or more first conduction material;

The coherent type three-dimensional structure of conduction that can provide active material absorption and carrying to support class tube bank type three-dimensional electronic channel architecture is provided by one or more second conduction material; And

Formed the three-dimensional clearance space structure that electrolyte or electrolyte ion conduction pathway can be provided by the first conduction material and the second conduction material.

2. conductive structures of polar plate according to claim 1, wherein, this first conduction material is selected from the cohort that tubulose conduction material, strip conduction material, shaft-like conduction material and fibrous conduction material are constituted.

3. conductive structures of polar plate according to claim 1, wherein, the applying bunchiness assembled each other by this first conduction material and consecutive reticulates three-dimensional structure.

4. conductive structures of polar plate according to claim 1, wherein, this first conduction material is a carbonaceous system conduction material.

5. conductive structures of polar plate according to claim 4, wherein, this carbonaceous system conduction material is selected from the cohort that carbon pipe, carbon fibre and vapor deposition carbon fibre are constituted.

6. conductive structures of polar plate according to claim 1, wherein, this first conduction material is that non-carbonaceous is the conduction material.

7. conductive structures of polar plate according to claim 6, wherein, this non-carbonaceous is that the conduction material is selected from metal, conduction is answered the cohort that material and conducting polymer are constituted.

8. conductive structures of polar plate according to claim 1, wherein, this second conduction material is selected from sheet conduction material, stratiform conduction material, reaches the graininess conduction cohort that material constituted.

9. conductive structures of polar plate according to claim 1, wherein, this second conduction material is the superposition three-dimensional structure that links each other.

10. conductive structures of polar plate according to claim 1, wherein, this second conduction material is a carbonaceous system conduction material.

11. conductive structures of polar plate according to claim 10, wherein, this carbonaceous system conduction material is selected from the cohort that carbon black, graphite and carbon 60 are constituted.

12. conductive structures of polar plate according to claim 1, wherein, this second conduction material is that non-carbonaceous is the conduction material.

13. conductive structures of polar plate according to claim 12, wherein, this non-carbonaceous is that the conduction material is selected from metal, conduction is answered the cohort that material and conducting polymer are constituted.

14. conductive structures of polar plate according to claim 1, wherein, this three-dimensional clearance space structure is meant the clearance space beyond the coherent type three-dimensional structure of class tube bank type three-dimensional electronic channel architecture and conduction.

15. conductive structures of polar plate according to claim 1, wherein, this active material is selected from the cohort that lithium and cobalt oxides (LiCoO2), lithium manganese oxide (LiMn2O4), lithium nickel oxide (LiNiO2) and iron lithium phosphate oxide (LiFePO4) are constituted.

16. conductive structures of polar plate according to claim 1, wherein, such tube bank type three-dimensional electronic channel architecture links up with conduction and combines typing with adhesive agent between the type three-dimensional structure.

17. conductive structures of polar plate according to claim 1 further comprises the pole plate base material.

18. conductive structures of polar plate according to claim 17, wherein, this pole plate base material is selected from the cohort that aluminium foil, alloy foil, nickel foil, platinum foil and copper alloy foil constitute.

19. conductive structures of polar plate according to claim 17, wherein, the coherent type three-dimensional structure of such tube bank type three-dimensional electronic channel architecture and conduction is passed through to the utmost point plate substrate of macromolecule adhesive agent gluing.

20. conductive structures of polar plate according to claim 19, wherein, this macromolecule adhesive agent is selected from the cohort that polyvinylidene fluoride, poly aromatic base sulfone and polytetrafluoroethylene are constituted.

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