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Li-ion secondary battery formation method

A technology of secondary battery and chemical formation method, which is applied in secondary battery, secondary battery repair/maintenance, secondary battery charging/discharging, etc., and can solve the problems of increased leakage, battery cycle performance and high-current discharge performance, etc. Integrating unsatisfactory electrochemical performance and other problems, it can achieve the effect of increasing capacity, improving cycle performance and high-current discharge performance, and reducing the difficulty of liquid injection

Inactive Publication Date: 2010-03-24
BYD CO LTD
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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 that the existing chemical formation method is not suitable for lithium ion secondary batteries obtained by using lithium iron phosphate as the positive electrode active material, and the comprehensive electrochemical properties such as cycle performance and high-current discharge performance of the battery after formation are not ideal. The disadvantage is to provide a method for the formation of a lithium-ion secondary battery that uses lithium iron phosphate as the positive electrode active material so that the battery has good cycle performance and high-current discharge performance.
This method not only solves the problem of a corresponding increase in the amount of liquid leakage during a formation process when the electrolyte is injected too much at one time, but also greatly reduces the difficulty of liquid injection, ensures the residual amount of electrolyte in the battery, and can effectively control the thickness of the battery. , this method is especially suitable for lithium-ion secondary batteries with lithium iron phosphate as the positive electrode active material, which can effectively increase the capacity of the battery, improve the cycle performance and high-current discharge performance of the battery

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] This example illustrates the preparation of a lithium ion secondary battery.

[0031] (1) Preparation of positive electrode

[0032] 100 grams of positive electrode active ingredient lithium ferrous phosphate, 2 grams of binder polyvinylidene fluoride (PVDF), 3 grams of conductive agent carbon black and 40 grams of N-methylpyrrolidone are mixed, then stirred in a vacuum mixer to form a uniform Positive slurry.

[0033] 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 ).

[0034] (2) Preparation of negative electrode

[0035] 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 negative electrode slurry.

[0036] The slurry was un...

Embodiment 2

[0041] This embodiment illustrates the formation method of the lithium ion secondary battery provided by the present invention

[0042] At normal pressure and 40°C, first charge the battery containing 2.5 grams of electrolyte prepared in Example 1 to 3.4 volts at a current of 0.05C, and then inject 1.2 grams of electrolyte into the battery again under normal pressure , continue to charge at 40° C. with a constant current of 1 C to 3.8 volts to complete the formation, and seal the liquid injection hole to obtain a square lithium-ion battery A1 with a model number of 053450 after formation.

Embodiment 3

[0044] This embodiment illustrates the formation method of the lithium ion secondary battery provided by the present invention

[0045] According to the method of Example 2, the battery containing 2.5 grams of electrolyte prepared in Example 1 was formed, the difference is that after charging to 3.8 volts at a constant current of 1C, the battery was placed at 45°C for 24 hours Finally, the formation is completed, and the liquid injection hole is sealed to obtain a square lithium-ion battery A2 with a model number of 053450 after formation.

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Abstract

The invention relates to a formation method of a lithium ion second battery. The method includes the steps that: electrolyte is injected into the lithium ion second battery, the battery is charged upat the formation temperature of the lithium ion second battery. The charging method includes a first charging process and a second charging process. After the first charging process, the electrolyte is once more injected into the lithium ion second battery, wherein, the total quantity of the electrolyte injected before and after the first charge process is adopted as benchmark, the proportion of the electrolyte injected before the first charge process accounts for 50 percent to 80 percent of the total weight, and the proportion of the electrolyte injected after the first charge process accounts for 20 percent to 50 percent of the total weight. The anode active substance of the lithium ion second battery is lithium iron phosphate. The method is particularly applicable to the lithium ion second battery, the anode active substance of which is lithium iron phosphate, can effectively improve the capacity of the battery, and also enhance the circulation performance and heavy current discharge performance of the battery.

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 existing lithium-ion secondary batteries, sealing formation and opening formation. The sealing formation is to seal the liquid injection hole after the electrolyte is injected, and then perform the battery formation, and at the same time form the SEI film (Solid Electrolyte Interface) on the surface of the negative electrode through the electrochemical reaction during charging. However, some gases, such as hydrogen fluoride, carbon monoxide, carbon dioxid...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M10/058H01M10/0525H01M10/44
CPCY02E60/122Y02E60/10Y02P70/50
Inventor 黄玉元张才毓姜占锋
Owner BYD CO LTD