A kind of preparation method of lithium ion secondary battery

A secondary battery, lithium-ion technology, applied in the field of lithium-ion batteries, can solve the problems of poor charge and discharge performance of battery rate, poor high temperature storage performance, etc.

Active Publication Date: 2016-05-11
SHANGHAI BYD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] The present invention aims to solve the problem that the SEI film prepared by battery formation in the prior art cannot have good lithium conductivity while having high electronic insulation, good thermal stability and chemical stability, resulting in poor rate charge and discharge performance of the battery. Or the technical problem of poor high-temperature storage performance, providing a preparation method of a lithium-ion secondary battery with excellent high-temperature stability and rate charge-discharge performance

Method used

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Examples

Experimental program
Comparison scheme
Effect test

preparation example Construction

[0011] The present invention provides a method for preparing a lithium ion secondary battery. The method includes injecting a non-aqueous electrolyte into a battery case equipped with battery pole cores, and then forming the non-aqueous electrolyte infused battery; wherein, The chemical composition is carried out in three stages. The first stage is low current and low voltage constant current and constant voltage charging, the second stage is low current constant current and constant voltage charging, and the third stage is constant current charging; After the end of the first stage, additives are added to the non-aqueous electrolyte before the third stage starts; the additives are at least one of water, hydrofluoric acid and fluoroethylene carbonate.

[0012] Generally speaking, the composition of the electrolyte and the formation system closely affect the composition and composition of the SEI membrane. The solute, solvent and additives of the electrolyte all affect the perform...

Embodiment 1

[0051] (1) Preparation of positive electrode

[0052] Lithium iron phosphate (LiFePO 4 ), and conductive carbon black (CB), polyvinylidene fluoride (PVDF), N-methylpyrrolidone (NMP) according to the weight ratio of LiFePO 4 : CB: PVDF: NMP=100: 5: 3.5: 110 to prepare positive electrode slurry, stir at high speed for 2 hours to prepare positive electrode slurry. Double-sided dressing on aluminum foil with a thickness of 16um, uniformly coating. Then it is dried at 120℃, rolled and cut into positive electrode pieces. The size of the electrode pieces is: length×width×thickness=471mm×42mm×140um, and the bulk density is 2.0g / cm 3 .

[0053] (2) Preparation of negative electrode

[0054] The weight ratio of graphite (C), conductive carbon black (SuperP), styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC) and deionized water is C: SuperP: SBR: CMC: H2O = 100: 2: 4 :2:130 The positive electrode slurry is prepared, and the negative electrode slurry is prepared after uniform stirr...

Embodiment 2

[0061] The battery was prepared by the same method as in Example 1, except that the additive was HF, and the amount of HF was 25ppm. First, the battery was charged at a constant current of 0.005C to 1.6V, and the voltage was constant at a voltage of 1.6V. Then charge with a constant current of 0.01C until the cut-off of 2.55V. At this time, add additives at a constant voltage at a cut-off voltage of 2.55V for 2 hours; finally charge with a constant current of 0.1C until the cut-off of 3.7V. The battery S2 was prepared.

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Abstract

The invention provides a method for preparing a lithium-ion secondary battery, the method comprising injecting a non-aqueous electrolyte into a battery casing equipped with a battery pole core, and then forming the battery injected with the non-aqueous electrolyte; wherein, The formation is carried out in three stages, the first stage is constant current and constant voltage charging with small current and low voltage, the second stage is small current constant current and constant voltage charging, and the third stage is constant current charging; Add additives to the non-aqueous electrolytic solution after the first stage ends, and before the third stage starts; the additives are at least one of water, hydrofluoric acid and fluoroethylene carbonate. The battery prepared by the method of the invention has excellent high temperature stability and rate charge and discharge performance.

Description

Technical field [0001] The invention belongs to the field of lithium ion batteries, and particularly relates to a method for preparing a lithium ion secondary battery. Background technique [0002] Lithium-ion batteries have the advantages of high specific energy, high working voltage, low self-discharge rate, long cycle life, and no pollution. They have been widely used in mobile communications, notebook computers, power tools and electric vehicles. These fields not only require high reversible capacity, long cycle / storage life, good safety, and low cost, but also require excellent rate charge and discharge performance and high and low temperature performance. [0003] The performance of lithium ion batteries is closely related to its solid electrolyte interface membrane (SEI membrane). Excellent SEI film (dense, high lithium conductivity and electronic insulation, good thermal stability and chemical stability) can greatly improve the overall performance of the battery. [0004] S...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M10/058H01M10/0525
CPCH01M10/0525H01M10/058H01M10/4235H01M10/446Y02E60/10Y02P70/50
Inventor 沈晞沈益顺颜海鹏张欣欣张学全
Owner SHANGHAI BYD
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