CN101262078A - Rapidly chargeable lithium-ion battery and preparation method thereof - Google Patents

Abstract

The invention discloses a fast-chargeable lithium-ion battery, comprising a positive electrode, a negative electrode, a diaphragm inserted between the positive electrode and the negative electrode, and an organic electrolyte, wherein the active material of the negative electrode is submicron titanic acid Lithium, the active materials of the positive electrode are lithium manganate (LiMn ₂ O ₄ ), lithium iron phosphate (LiFePO ₄ ), lithium nickel cobaltate (LiNi _x Co _y M _z O ₂ ) and ternary materials (LiNi _x Mn _x Co One or more of _1-2x O ₂ ), or a mixture of lithium cobaltate (LiCoO ₂ ) and one of them, the electrolyte uses lithium hexafluorophosphate (LiPF ₆ ) as the electrolyte, ethylene carbonate (EC), dimethyl The multi-component mixture of diethyl carbonate (DMC) and ethyl methyl carbonate (EMC) is used as a solvent, and the invention also discloses a preparation method of the battery. The lithium ion battery of the invention has excellent fast charging and discharging performance.

Description

Rapidly chargeable lithium-ion battery and preparation method thereof

technical field

The invention relates to the technical field of lithium-ion battery energy, in particular to a fast-chargeable lithium-ion battery and a preparation method thereof.

Background technique

Lithium-ion batteries have the characteristics of high specific energy, high voltage platform, long cycle life, wide operating temperature range, no memory effect, and environmental friendliness. Since their inception, they have developed rapidly and are widely used in various military and civilian applications. Portable electrical appliances, such as mobile phones, notebook computers, electric tools, electronic instruments, etc., are gradually being used in electric vehicles, armed equipment, etc.

In the previous research and application, the discharge performance, safety performance and storage performance of lithium-ion batteries were mainly assessed, and the charging performance of lithium-ion batteries was generally not required. However, with the application of lithium-ion batteries in electric tools, electric vehicles, etc., people hope that lithium-ion batteries also have good charging performance, so as to reduce the waiting time for battery charging.

At present, the lithium-ion battery system is mostly LiCoO ₂ /multiple electrolyte system/C, and the charging system mostly adopts constant current charging (current is less than or equal to 1I _t A), and then constant voltage charging, and the charging time is more than 1 hour. Its high-current charging situation is: charging with 10I _t A current can only charge about 30% within 5 minutes; charging with 5I _t A current can only charge about 50% within 10 minutes. Therefore, the fast charging effect of this system is relatively poor, and it cannot meet the requirements for fast charging of electric tools and electric vehicle batteries.

Contents of the invention

In order to solve the above problems, the object of the present invention is to provide a lithium-ion battery capable of rapid charge and discharge with better fast charge effect and a preparation method thereof.

The purpose of the present invention is achieved through the following technical solutions:

A fast-chargeable lithium-ion battery, comprising a positive electrode, a negative electrode, a diaphragm inserted between the positive electrode and the negative electrode, and an organic electrolyte, wherein the active material of the negative electrode is submicron lithium titanate, The active materials of the positive electrode are lithium manganate (LiMn ₂ O ₄ ), lithium iron phosphate (LiFePO ₄ ), lithium nickel cobaltate (LiNi _x Co _y M _z O ₂ ) and ternary materials (LiNi _x Mn _x Co _1-2x O ₂ ), or a mixture of lithium cobaltate (LiCoO ₂ ) and one of them, the electrolyte uses lithium hexafluorophosphate (LiPF ₆ ) as the electrolyte, and ethylene carbonate (EC ), a multivariate mixture of dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) as the solvent.

The particle size (D ₅₀ ) of the aforementioned submicron lithium titanate is less than 10 μm, and the specific surface area is greater than 1 m ² /g.

In the above _LiNix Co _y M _z O ₂ , M is Al, Mg, Sr, Sn, Mn or Fe, where 0<X<1, 0<Y<1, 0<Z<1, X+Y+Z =1; in the LiNi _x Mn _x Co _1-2x O ₂ mentioned above, 0<X≤0.5.

A preparation method of a rapidly chargeable lithium-ion battery, comprising the following steps:

1) 70%-98% by weight of submicron lithium titanate, 1%-15% by weight of conductive agent and 1%-10% by weight of binder are dissolved in a solvent to make negative electrode slurry, with a thickness of 10 μm The copper foil is used as a current collector, and the negative electrode slurry is coated on the copper foil and dried to make a pole piece, and then the pole piece is rolled and cut to make a negative electrode;

2) 70%-98% by weight of positive active material, 1%-10% of conductive agent and 1%-10% of binder are dissolved in a solvent to make positive electrode slurry, with 15 μm thick aluminum foil as current collector , apply the positive electrode slurry to the aluminum foil and dry it to make a pole piece, then roll and cut the pole piece to make a positive electrode;

3) The special polypropylene resin separator for lithium-ion batteries is used as the battery separator, the electrolyte uses LiPF ₆ as the electrolyte, and ethylene carbonate (EC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC) The multivariate mixture is the solvent;

4) Wind the positive electrode (pole piece), the negative electrode (pole piece) and the diaphragm together into a cell, put it into the battery case, then inject the electrolyte and seal it;

5) Chemical post-processing.

In the above preparation method, the coating amounts of the positive and negative electrodes are both less than 48 mg/cm ² .

The above-mentioned conductive agent is super conductive carbon black or conductive graphite.

The above-mentioned binders are polytetrafluoroethylene and polyvinylidene fluoride.

The above-mentioned solvent is N-methylpyrrolidone, dimethylamide or dimethylacetamide.

The fast-chargeable lithium ion battery of the present invention adopts submicron lithium titanate (Li ₄ Ti ₅ O ₁₂ ) as the negative electrode active material, and lithium manganate (LiMn ₂ O ₄ ), lithium iron phosphate (LiFePO ₄ ), one of lithium nickel cobaltate (LiNi _x Co _y M _z O ₂ ) and ternary materials (LiNi _x Mn _x Co _1-2x O ₂ ) is the positive electrode active material, so that the prepared lithium-ion battery Has excellent fast charge and discharge performance.

Description of drawings

Fig. 1 is the flow chart of the preparation method of the rapidly chargeable lithium-ion battery of the present invention;

Fig. 2 is in one embodiment of the present invention, the charging curve of battery under different currents;

Fig. 3 is in one embodiment of the present invention, the discharge curve of battery under different currents;

Fig. 4 is in one embodiment of the present invention, 300 cycle curves of battery;

Fig. 5 is in another embodiment of the present invention, the charging curve of battery under different currents;

Fig. 6 is another embodiment of the present invention, the discharge curve of the battery under different currents:

Fig. 7 is a 300 cycle curve of the battery in another embodiment of the present invention.

Detailed ways

The fast-chargeable lithium-ion battery of the present invention includes: a positive electrode, a negative electrode, a diaphragm inserted between the positive electrode and the negative electrode, and an organic electrolyte, wherein the active material of the negative electrode is submicron lithium titanate, and the positive electrode The active materials of the electrodes are lithium manganese oxide (LiMn ₂ O ₄ ), lithium iron phosphate (LiFePO ₄ ), lithium nickel cobalt oxide (LiNi _x Co _y M _z O ₂ ) and ternary materials (LiNi _x Mn _x Co _1-2x One or more of O ₂ ) or a mixture of lithium cobaltate (LiCoO ₂ ) and one of them, the electrolyte uses lithium hexafluorophosphate (LiPF ₆ ) as the electrolyte, ethylene carbonate (EC), dimethyl A multicomponent mixture of carbonate (DMC) and ethylmethylcarbonate (EMC) was the solvent.

Wherein, the particle size (D ₅₀ ) of the above-mentioned submicron lithium titanate is less than 10 μm, and the specific surface area is greater than 1 m ² /g.

Preferably, the active material of the positive electrode is lithium manganate.

The preparation method of the fast-chargeable lithium-ion battery of the present invention may further comprise the steps:

1) 70%-98% by weight of submicron lithium titanate, 1%-15% by weight of conductive agent and 1%-10% by weight of binder are dissolved in a solvent to make negative electrode slurry, with a thickness of 10 μm The copper foil is used as a current collector, and the negative electrode slurry is coated on the copper foil and dried to make a pole piece, and then the pole piece is rolled and cut to make a negative electrode;

2) Dissolving 70%-98% by weight of lithium manganate, 1%-10% conductive agent and 1%-10% binder in a solvent to make positive electrode slurry, with 15 μm thick aluminum foil as current collector , apply the positive electrode slurry to the aluminum foil and dry it to make a pole piece, then roll and cut the pole piece to make a negative electrode;

3) The special polypropylene resin separator for lithium-ion batteries is used as the battery separator, the electrolyte uses LiPF ₆ as the electrolyte, and ethylene carbonate (EC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC) The multivariate mixture is the solvent;

4) Wind the positive electrode (pole piece), the negative electrode (pole piece) and the diaphragm together into a cell, put it into the battery case, then inject the electrolyte and seal it;

5) Chemical post-processing.

The coating amount of the above-mentioned negative electrode is less than 48 mg/cm ² , and the coating amount of the positive electrode is less than 48 mg/cm ²

The above-mentioned conductive agent is super conductive carbon black or conductive graphite, and the above-mentioned binder is polytetrafluoroethylene, polyvinylidene fluoride or polymer resin.

The above-mentioned solvent is N-methylpyrrolidone, dimethylamide or dimethylacetamide, preferably N-methylpyrrolidone.

The preparation method of the fast-chargeable lithium-ion battery of the present invention will be described in detail below in conjunction with specific examples.

Example 1

In terms of mass percentage (the same below), 85% of the positive electrode active material lithium manganate, 5% of super conductive carbon black, 10% of the binder polyvinylidene fluoride, with N-methylpyrrolidone as a solvent, mixed into a paste body, with 15 μm thick aluminum foil as the current collector, the paste was coated on the aluminum foil and dried.

The pole piece was rolled, cut and welded to make a positive pole piece with an electrode density of 2.9g/cm ³ .

80% of the negative electrode material submicron lithium titanate (D ₅₀ is 0.185 μm, the specific surface area is 5.2m ² /g) and 8% of super conductive carbon black, 12% of the binder polyvinylidene fluoride, with N -Methylpyrrolidone is used as a solvent to make a paste, and a 10 μm thick copper foil is used as a current collector. The paste is coated on the copper foil and dried.

The pole piece was rolled, cut and welded with lugs to make a negative pole piece with an electrode density of 3.8g/cm ³ .

Polypropylene resin lithium-ion battery separator is used as the battery separator.

The electrolyte is LiPF ₆ , and the solvent system is a multivariate mixture of ethylene carbonate (EC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC) and the like.

The positive electrode (pole piece), negative electrode (pole piece) and the diaphragm are wound into a battery core, after shaping, put it into the battery case, then inject the electrolyte and seal it.

It is post-chemically processed.

Prepare ICP053048 lithium-ion square battery, charge with 10ItA electric current, can charge 80.1% in 5 minutes.

Example 2

The difference from Example 1 is that the proportions of the positive electrode material lithium manganate, super conductive carbon black, and binder in the positive electrode are 90%, 3%, and 7% respectively; the negative electrode material in the negative electrode is submicron lithium titanate , super conductive carbon black, and binder ratios are: 87%, 5%, and 8%, respectively.

Prepare the square lithium ion battery of ICP053048, charge with 10ItA electric current, can charge 82.8% in 5 minutes.

The charging and discharging curves and cycle curves of the fabricated battery under different currents are shown in Fig. 2 to Fig. 4 .

Example 3

The difference from Example 1 is that the ratios of the positive electrode material lithium manganate, super conductive carbon black, and binder in the positive electrode are 93%, 2%, and 5% respectively; the negative electrode material in the negative electrode is submicron lithium titanate , super conductive carbon black, and binder ratios are: 90%, 3%, and 7%, respectively.

The 10ItA current charge, 10ItA discharge and 300 cycle data of the lithium-ion battery made by the above-mentioned 3 embodiments are shown in Table 1.

The battery performance of table 1 embodiment 1-embodiment 3

serial number Average battery capacity mAh 10ItA, 5min charging% 10ItA discharge% 300 cycles % Example 1 330 80.1 81.3 81.2 Example 2 400 82.8 85.6 85.7 Example 3 420 80.9 82.7 84.8

Example 4:

The difference from Example 1 is that conductive graphite is used as the conductive agent; the ratios of lithium manganate, conductive graphite, and binder in the positive electrode are respectively: 89%, 4%, and 7%; the negative electrode material in the negative electrode is submicron titanium The proportions of lithium acid lithium, conductive graphite, and binder are respectively: 86%, 6%, and 8%.

Prepare the square lithium ion battery of ICP053048, charge with 10ItA electric current, can charge 81.2% in 5 minutes.

Example 5:

The difference from Example 1 is that the active material in the positive electrode is lithium iron phosphate; the ratios of lithium iron phosphate, super conductive carbon black, and binder in the positive electrode are respectively: 90%, 3%, and 7%; The proportions of submicron lithium titanate, super conductive carbon black, and binder of negative electrode materials are: 87%, 5%, and 8%, respectively.

Prepare the square lithium ion battery of ICP053048, charge with 10ItA electric current, can charge 82.9% in 5 minutes.

The charge and discharge curves and cycle curves of the fabricated battery under different currents are shown in Figures 5 to 7.

The battery performance of table 2 embodiment 4-5

serial number Average battery capacity mAh 10ItA, 5min charging% 10ItA Discharge% 300 cycles % Example 4 385 81.2 80.5 82.6 Example 5 360 82.9 86.6 90.1

Example 6

The difference from Example 1 is that the active material in the positive electrode is lithium nickel cobaltate material (LiNi _0.8 Co _0.15 Al _0.05 O ₂ ), and the proportions of lithium nickel cobaltate, super conductive carbon black, and binder in the positive electrode are respectively They are: 90%, 3%, 7%; the proportions of submicron lithium titanate, super conductive carbon black, and binder in the negative electrode are: 87%, 5%, and 8%, respectively.

Prepare the square lithium ion battery of ICP053048, charge with 10ItA electric current, can charge 80.5% in 5 minutes.

Example 7

The difference from Example 1 is that the active material in the positive electrode is a ternary material (LiNi _1/3 Co _1/3 Mn _1/3 O ₂ ); in the positive electrode, lithium nickel cobaltate, super conductive carbon black, bonded The proportions of the additives are: 90%, 3%, and 7%; the proportions of the negative electrode materials submicron lithium titanate, super conductive carbon black, and binder in the negative electrode are: 87%, 5%, and 8%, respectively.

Prepare the square lithium ion battery of ICP053048, charge with 10ItA electric current, can charge 82.4% in 5 minutes.

Example 8

The difference from Example 1 is that the active material in the positive electrode is a mixed material of lithium cobaltate (LiCoO ₂ ) and ternary material (LiNi _1/3 Co _1/3 Mn _1/3 O ₂ ) (mixed at 9:1 ); the proportions of the mixed material, super conductive carbon black, and binder in the positive electrode are respectively: 90%, 3%, and 7%; The proportions are: 87%, 5%, 8%.

Prepare the square lithium ion battery of ICP053048, charge with 10ItA electric current, can charge 83.2% in 5 minutes.

Example 9

The difference from Example 1 is that the active material in the positive electrode is a mixed material of lithium cobaltate (LiCoO ₂ ) and lithium manganate (mixed at 9:1); the mixed material in the positive electrode, super conductive carbon black, binder The proportions are: 90%, 3%, and 7%; the proportions of the negative electrode materials submicron lithium titanate, super conductive carbon black, and binder in the negative electrode are: 87%, 5%, and 8%, respectively.

Prepare the square lithium ion battery of ICP053048, charge with 10ItA electric current, can charge 82.6% in 5 minutes.

As _{can be seen from the accompanying drawings and the data in Table 1-2, the lithium ion battery of the present invention can be charged to more than 80% of the battery capacity within 5 minutes with a current charge of 10I t A} ; More than 80% of the battery capacity; after 300 cycles, the battery capacity remains above 80%, with excellent fast charge and discharge performance.

Claims (8)

1. the lithium ion battery of a quickly-chargeable, comprise positive electrode, negative electrode, be inserted in barrier film and organic electrolyte between positive electrode and the negative electrode, it is characterized in that: the active material of described negative electrode is the submicron order lithium titanate, and the active material of described positive electrode is LiMn2O4 (LiMn ₂O ₄), LiFePO4 (LiFePO ₄), lithium nickel cobalt dioxide (LiNi _xCo _yM _zO ₂) and ternary material (LiNi _xMn _xCo _1-2xO ₂) in one or more or cobalt acid lithium (LiCoO ₂) and wherein a kind of mixture, described electrolyte is with lithium hexafluoro phosphate (LiPF ₆) be electrolyte, be solvent with the multicomponent mixture of vinyl carbonate (EC), dimethyl carbonate (DMC) and ethyl-methyl carbonic ester (EMC).

2. lithium ion battery according to claim 1 is characterized in that: the granularity (D of described submicron order lithium titanate ₅₀) less than 10 μ m, specific area is greater than 1m ²/ g.

3. lithium ion battery according to claim 1 is characterized in that: described LiNi _xCo _yM _zO ₂In, M is Al, Mg, Sr, Sn, Mn or Fe, 0＜X＜1,0＜Y＜1,0＜Z＜1 wherein, X+Y+Z=1; Described LiNi _xMn _xCo _1-2xO ₂In, 0＜X≤0.5.

4. the preparation method of the lithium ion battery of a quickly-chargeable may further comprise the steps:

1) binding agent of the conductive agent of the submicron order lithium titanate of 70%-98% weight, 1%-15% weight and 1%-10% weight is dissolved in makes cathode size in the solvent, with the thick Copper Foil of 10 μ m is collector, be coated onto on the Copper Foil cathode size and drying, make pole piece, then pole piece rolled, shear and make negative electrode;

2) binding agent of the conductive agent of the positive active material of 70%-98% weight, 1%-10% and 1%-10% is dissolved in makes anode sizing agent in the solvent, with the thick aluminium foil of 15 μ m is collector, be coated on the aluminium foil anode sizing agent and drying, make pole piece, then pole piece rolled, shear and make positive electrode;

3) adopting the polypropylene dedicated resin barrier film of lithium ion battery is battery diaphragm, and electrolyte is with LiPF ₆Being electrolyte, is solvent with the multicomponent mixture of vinyl carbonate (EC), dimethyl carbonate (DMC), ethyl-methyl carbonic ester (EMC);

4) described positive electrode (pole piece), negative electrode (pole piece) are wound into electric core with barrier film, put into battery case, inject electrolyte then and seal;

5) change into reprocessing.

5. preparation method according to claim 4 is characterized in that: the coated weight of positive and negative electrode is all less than 48mg/cm ²

6. preparation method according to claim 4 is characterized in that: described conductive agent is super conductive black or electrically conductive graphite.

7. preparation method according to claim 4 is characterized in that: described binding agent is polytetrafluoroethylene, Kynoar.

8. preparation method according to claim 4 is characterized in that: described solvent is N-methyl pyrrolidone, dimethylformamide or dimethylacetylamide.

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