Formation and validation method capable of improving cycle performance of lithium iron phosphate battery

A lithium iron phosphate battery, cycle performance technology, applied in the field of lithium ion batteries, can solve problems such as failure to achieve effective formation or verification, uneven and dense SEI film formation, affecting battery liquid retention, etc., to achieve good performance of lithium batteries , Improving the first discharge efficiency and reducing the effect of the unformed dead zone area

Inactive Publication Date: 2018-05-18
桑顿新能源科技(长沙)有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The formation process of these two patents does not completely match the battery system. The solid electrolyte film at the negative electrode interface is not formed perfectly during the formation, and the SEI film is formed unevenly, densely or too thickly; this will affect the battery’s fluid retention, capacity, and internal resistance, and ultimately affect the battery. The cycle life has not reached practical and effective formation or verification, and has certain limitations

Method used

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  • Formation and validation method capable of improving cycle performance of lithium iron phosphate battery
  • Formation and validation method capable of improving cycle performance of lithium iron phosphate battery
  • Formation and validation method capable of improving cycle performance of lithium iron phosphate battery

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0045] The model of the prepared square soft pack battery is 90161227-25Ah; the positive electrode active material powder is lithium iron phosphate; the negative electrode active material is graphite; the electrolyte is 1mol / L LiPF 6 / (EC+DMC+DEC) (volume ratio 1:1:1). Positive electrode: LFP, conductive agent and binder are prepared according to the ratio (mass ratio) of 92.5:4:3.5; the ratio of negative electrode is: graphite, conductive agent, CMC and binder (SBR) according to 94.5:2:1:2.5 Ratio (mass ratio) for preparation. In the early stage, the positive and negative electrode powders are mixed, coated, rolled, sheeted, assembled, and baked. After baking, the moisture content is ≤300ppm; the weight of the excess electrolyte injected is 260±3g; it is placed in a dry place at 45°C for 24 hours; then the battery is subjected to hot pressing at 80°C and cold at 20°C through the main board pressure of 0.3Mpa. pressure treatment.

[0046] The obtained square pouch battery i...

Embodiment 2

[0050] The specific process is with reference to embodiment 1, and difference with embodiment 1 is:

[0051] The obtained square pouch battery is preformed in stages at room temperature, and the specific process is as follows:

[0052] S1: Charge the battery with a constant current of 0.01C for 2 hours, and the upper limit voltage is 3.4V; S2: Charge the battery with a constant current of 0.04C for 5 hours, and the upper limit voltage is 3.5V; S3: Finally, charge the battery with a constant current of 0.1C for 5 hours, The upper limit voltage is 3.65V.

Embodiment 3

[0054] The specific process is with reference to embodiment 1, and difference with embodiment 1 is:

[0055] The obtained square pouch battery is preformed in stages at room temperature, and the specific process is as follows:

[0056] S1: Charge the battery with a constant current of 0.02C for 1 hour, and the upper limit voltage is 3.4V; S2: Charge the battery with a constant current of 0.04C for 5 hours, and the upper limit voltage is 3.5V; S3: Finally, charge the battery with a constant current of 0.1C for 6 hours, The upper limit voltage is 3.65V.

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Abstract

The invention provides a formation and validation method capable of improving the cycle performance of a lithium iron phosphate battery. The method comprises the steps of preparing a square soft package battery; carrying out normal-temperature staged preformation; completing a preformation stage and then carrying out secondary packaging on the battery; and finally carrying out battery capacity grading and validation. A matched formation and validation method capable of improving the cycle performance of the lithium iron phosphate battery is established for a specific square soft package powerbattery system; and in the process of the method, the factors, such as corresponding internal resistance change, fluid loss change, charge-discharge efficiency and scanning interface of the battery are analyzed to form the formation and validation method capable of improving the cycle performance of the lithium iron phosphate battery, which is optimal in SEI film, optimal in battery performance and longest in cycle life.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a formation and verification method for improving cycle performance of lithium iron phosphate batteries. Background technique [0002] Lithium iron phosphate system pouch batteries have the characteristics of high safety, low cost, and long life, and are mainly used in fields such as electric buses, buses, communication base stations, and energy storage base stations. After the lithium-ion battery is manufactured, the process of activating its internal positive and negative electrode materials through a certain charge and discharge method to improve the battery's charge and discharge performance, self-discharge, storage and other comprehensive performance is called formation. The formation of lithium battery is the initialization of the battery, which can activate the active material of the battery. This process is a very complicated process, and it is also a very i...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M10/058
CPCH01M10/058Y02E60/10Y02P70/50
Inventor 余开明娄中良温转萍崔俊葳
Owner 桑顿新能源科技(长沙)有限公司
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