Lithium ion battery

A lithium-ion battery and electrolyte technology, applied in battery electrodes, secondary batteries, non-aqueous electrolyte batteries, etc., can solve the problems of poor battery cycle performance and inability to firmly bond silicon negative electrodes

Inactive Publication Date: 2019-05-17
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] Aiming at the problem that the volume of the existing silicon negative electrode changes greatly during the charging and discharging process, and the existing binder cannot firmly bond the silicon negati

Method used

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Examples

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preparation example Construction

[0038] The preparation of structural formula one binding agent:

[0039] (1) Add the mixed solution of chitosan, dichloroacetic acid and formamide dropwise to the mixed solution of chlorosulfonic acid / dimethylformamide, stir for 2h, and filter to obtain the filtrate;

[0040] (2) The filtrate obtained in step (1) is added dropwise in ethanol, filtered after stirring for 2h, and the precipitate obtained by filtration is washed three times with ethanol to obtain chitosan sulfate;

[0041] (3) Add acryloyl chloride / ether solution dropwise to glycinamide hydrochloride, deionized water, potassium carbonate / ether mixed solution and stir for 1 hour, then add HCl to adjust the pH of the solution to 3, and then wash the mixture with ether to remove organic phase, and vacuum evaporated the remaining ether, then adjusted the pH of the solution to neutral with NaOH solution, and freeze-dried the mixture;

[0042] (4) washing the mixture obtained in step (3) three times with a methanol / etha...

Embodiment 1

[0055] This embodiment is used to illustrate a lithium ion battery disclosed in the present invention and its preparation method.

[0056] 1) Preparation of electrolyte

[0057] Mix ethylene carbonate (EC), diethyl carbonate (DEC) and ethyl methyl carbonate (EMC) according to the mass ratio of EC:DEC:EMC=1:1:1, and then add lithium hexafluorophosphate (LiPF 6 ), its concentration is 1mol / L, then add the fluorinated cyclic carbonate shown in structural formula three by 5% of the total mass of the electrolyte.

[0058] 2) Preparation of positive electrode

[0059] Mix the positive electrode active material lithium nickel cobalt manganese oxide LiNi according to the mass ratio of 93:4:3 0.5 co 0.2 mn 0.3 o 2 , conductive carbon black Super-P and binder polyvinylidene fluoride (PVDF), and then disperse them in N-methyl-2-pyrrolidone (NMP) to obtain positive electrode slurry. The positive electrode slurry was uniformly coated on the aluminum foil, dried, calendered and vacuum...

Embodiment 2～12

[0067] Examples 2 to 12 are used to illustrate the lithium-ion battery disclosed in the present invention and its preparation method, including most of the operating steps in Example 1, the difference is that: the total amount of the negative active material, conductive agent and binder The mass percentage is 100%, the mass percentage of the conductive agent is fixed at 1%, and the mass percentage of the negative electrode active material changes with the ratio of the binder. The mass percentage and molecular weight of the binder are shown in Table 1. In addition, the fluorinated cyclic carbonate and mass percentage in the electrolyte are listed in Table 1.

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Abstract

The invention discloses a lithium ion battery and relates to the technical field of batteries. The lithium ion battery prepared by using a binder provided by the invention can more firmly adhere a silicon negative material, a conductive agent and a current collector together during the charging and discharging process of the silicon anode, which can suppress the increase in internal resistance inthe battery cycle and improve the cycle performance of the battery. In addition, the fluorinated cyclic carbonate in the electrolyte can form a SEI film with good mechanical properties on the surfaceof the negative electrode, which can well adapt to the volume expansion-shrinkage change of the silicon negative electrode without being destroyed, and has a better effect than using alone in combination with the adhesive of the structural formula 1.

Description

technical field [0001] The invention belongs to the field of lithium ion batteries, and in particular relates to a lithium ion battery. Background technique [0002] Lithium-ion batteries are widely used in the field of 3C consumer electronics because of their high energy density, high power, long cycle life and no memory effect. As countries vigorously advocate new energy and low-carbon economy, and with the development of electric vehicles, lithium-ion batteries have great application prospects. [0003] The binder is an essential key material for the electrode. It mainly plays the role of connecting the electrode active material, the conductive agent and the electrode current collector, maintaining the integrity of the electrode structure, thereby reducing the impedance of the electrode, and affecting various performances of the battery such as Internal resistance, rate performance, cycle life and so on all have a great influence. Commonly used binders are polyvinyliden...

Claims

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Application Information

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IPC IPC(8): H01M4/62H01M10/0525H01M10/0569H01M10/058
CPCY02E60/10Y02P70/50
Inventor 胡时光王朝阳易欢杨宇邓永红
Owner SOUTH CHINA UNIV OF TECH
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