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Li-ion secondary battery formation method

A technology of secondary battery and chemical formation method, which is applied in the direction of secondary battery, secondary battery charging/discharging, secondary battery repair/maintenance, etc., which can solve the problem of battery performance degradation, low battery capacity of lithium-ion secondary battery, and influence on SEI Membrane compactness stability and other issues

Active Publication Date: 2008-07-02
SHANGHAI BYD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to overcome the disadvantages of low battery capacity, high-temperature cycle performance and high-current discharge performance of the lithium-ion secondary battery obtained by the existing chemical conversion method, and to provide a battery with high capacity and good high-temperature cycle. Formation method of lithium ion secondary battery with high performance and high current discharge performance
When using the existing method to form the battery, charge it with a small current of 0.001-1C, and then charge it with a large current of 0.05-10C. The gas is mainly generated in the stage of charging with a small current and constant current. The charging time is short, and the gas cannot be slowly and fully discharged from the battery system, thereby affecting the compactness and stability of the SEI film formed on the surface of the negative electrode, and ultimately leading to a decline in battery performance

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023]This example illustrates the preparation of a lithium ion secondary battery.

[0024] (1) Preparation of positive electrode

[0025] 100 g of the positive active ingredient LiCoO 2 , 2 grams of binder polyvinylidene fluoride (PVDF), 3 grams of conductive agent acetylene black were added and mixed with 40 grams of N-methylpyrrolidone, and then stirred in a vacuum mixer to form a uniform positive electrode slurry.

[0026] The slurry was evenly coated on aluminum foil, then dried at 150°C, rolled, and cut to obtain a positive electrode with a size of 540×43.5 mm, which contained 5.8 grams of active ingredient LiCoO 2 .

[0027] (2) Preparation of negative electrode

[0028] Mix 100 grams of natural graphite, a negative electrode active ingredient, 1 gram of binder polyvinylidene fluoride (PVDF), and 40 grams of N-methylpyrrolidone, and then stir in a vacuum mixer to form a uniform negative electrode slurry.

[0029] The slurry was uniformly coated on a copper foil, the...

Embodiment 2

[0033] This example illustrates the preparation of a lithium ion secondary battery.

[0034] (1) Preparation of positive electrode

[0035] 93 grams of positive active ingredient lithium iron phosphate, 3 grams of binder polyvinylidene fluoride (PVDF), 3 grams of conductive agent carbon black, 1 gram of carbon fiber were added and mixed with 40 grams of N-methylpyrrolidone, and then mixed in a vacuum mixer Stir in medium to form a uniform positive electrode slurry.

[0036] The slurry was evenly coated on aluminum foil, then dried at 150°C, rolled, and cut to obtain a positive electrode with a size of 540×43.5 mm, which contained 5.2 grams of active ingredient lithium iron phosphate (LiFePO 4 ).

[0037] (2) Preparation of negative electrode

[0038] Mix 95 grams of artificial graphite as an active component of the negative electrode, 5 grams of binder polyvinylidene fluoride (PVDF) and 40 grams of N-methylpyrrolidone, and then stir in a vacuum mixer to form a uniform negat...

Embodiment 3

[0043] This embodiment illustrates the formation method of the lithium ion secondary battery provided by the present invention

[0044] Charge the liquid-injected battery obtained in Example 1 at 35°C and 0.1 MPa. The charging step includes first charging with a current of 0.005C to 3.2 volts, and performing constant voltage charging at this voltage, Until the battery current is 10 mA; then continue to charge the battery at a constant current of 0.1C to 4.2 volts to complete the formation, and seal the liquid injection hole to obtain the formed lithium-ion battery A1.

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Abstract

The invention relates to a formation method of lithium iron secondary battery. The method comprises the processes: the battery is charged under the formation temperature of the lithium iron secondary battery; the charge process comprises the processes: the continuous current of a first current is used for charging to the first voltage; the continuous voltage of the first voltage is used for charging to the cutoff current; the continuous current of a second current is used for charging to the second voltage. The second voltage is higher than the first voltage and the second current is higher than the first current. As the battery is carried out the formation using the formation method of the invention, the battery has a good comprehensive electrical-chemical performance such as a higher capacity, high-temperature circulation performance and a discharge performance for big current.

Description

technical field [0001] The invention relates to a method for forming a battery, in particular, the invention relates to a method for forming a lithium ion secondary battery. Background technique [0002] The formation step of lithium-ion rechargeable batteries is an important stage in the manufacture of batteries. The formation is related to the quality of the battery's capacity, cycle life, and safety performance. Formation is the process of charging a battery for the first time. There are mainly two ways of formation of the existing lithium-ion secondary batteries, sealed formation and open formation. Sealing formation is to seal the liquid injection hole after the electrolyte is injected, and then perform battery formation. During the formation process, gases such as ethylene, diethylene, phosphorus fluoride, and hydrogen fluoride are generated. These gases accumulate inside the battery and cause battery expansion. , the casing bulges, deforms, and even causes the batte...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M10/38H01M10/44H01M10/40H01M10/058
CPCY02E60/10Y02P70/50
Inventor 沈晞高艺潘福中
Owner SHANGHAI BYD
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