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CN-116093461-B - Rapid formation process of high-energy-density soft-package lithium ion battery

CN116093461BCN 116093461 BCN116093461 BCN 116093461BCN-116093461-B

Abstract

The application relates to the technical field of lithium batteries, in particular to a rapid formation process of a high-energy-density soft-package lithium ion battery. The application is formed by three stages of first constant current charge, second constant current charge and third constant current discharge. The first constant current charging stage can effectively regulate and control the growth speed of the SEI film in a mode of combining small-current, medium-current and large-current stepped charging, and improves the stability of the SEI film. The second constant current charging stage adopts medium current constant current charging, so that the liquid retention capacity of the battery can be improved, and the thickness expansion in the circulation process can be reduced. The third constant current discharge to the appointed state of charge can enhance the stability of the battery interface and reduce the capacity loss of the battery in the hot pressing process. The formation process can improve the comprehensive performance of the energy density soft-package lithium ion battery, shorten the formation time and improve the production efficiency.

Inventors

  • WANG YA
  • GUO LICHAO
  • KONG LINGLI
  • GUO JI
  • ZHANG ZHIRONG

Assignees

  • 天津力神电池股份有限公司

Dates

Publication Date
20260508
Application Date
20220923

Claims (6)

  1. 1. The rapid formation process of the high-energy-density soft-package lithium ion battery is characterized by comprising the following steps of: firstly, placing a fully infiltrated battery after liquid injection into clamp formation equipment, and standing the clamped battery to enable the temperature and the pressure of the battery to reach the preset temperature and the pressure of the formation equipment for formation; Step two, the first constant current charging is carried out to the battery in a step constant current charging mode of three constant current charging modes of small current, medium current and large current in a 0.05-2C interval until the battery is charged to a state of charge of 60% -75%, and the battery is dormant and kept stand; The three constant-current charging systems are respectively a small-current charging system, a medium-current charging system and a large-current charging system, wherein the charging current of the small-current charging system is 0.05C-0.3C, the charging charge state is less than or equal to 3 percent, the charging current of the medium-current charging system is 0.5C-1C, and the charging current of the medium-current charging system is 5% -10% of the charge state, and the charging current of the large-current charging system is 1.2C-2C, and the charging current of the large-current charging system is 60% -75% of the charge state; Thirdly, the second constant current charging is carried out to the full-power cut-off voltage of the battery by the current constant current charging of 0.5C-1C, and the battery is dormant and kept stand; And fourthly, discharging the third constant current to 55% -65% of the charge state at the current of 0.3C-1C, and cold pressing the battery after the process is finished.
  2. 2. The chemical synthesis process according to claim 1, wherein the clamp chemical synthesis temperature is 40-85 ℃ in the first step, the single cell surface pressure is controlled to be 0.3-1.4Mpa, the standing time is 1-10min, and the standing time in the second step and the third step is 1-10min.
  3. 3. The chemical synthesis process according to claim 1, wherein the small-current charging current is 0.1-0.2C, the charging state is 1%, the medium-current charging current is 0.5-0.7C, the charging state is 5%, and the large-current charging current is 1.2-1.5C, the charging state is 65%.
  4. 4. The chemical synthesis process according to claim 1, wherein the charging current in the second constant current charging process in the third step is 0.7C-1.0C.
  5. 5. The chemical synthesis process according to claim 1, wherein the third constant discharge current in the fourth step is 0.7C to 1.0C.
  6. 6. The chemical synthesis process according to claim 1, wherein in the fourth step, the cold pressing temperature is 25 ℃, the cold pressing pressure is the same as the chemical synthesis pressure, and the single cell surface pressure is controlled to be 0.3-1.4Mpa for 5-10min.

Description

Rapid formation process of high-energy-density soft-package lithium ion battery Technical Field The invention relates to the technical field of lithium batteries, in particular to a rapid formation process of a high-energy-density soft-package lithium ion battery. Background With the development of digital terminal products towards large screens and functional diversification, the energy density requirement of the lithium ion battery is continuously improved. In general, in order to increase the volumetric energy density of lithium ion batteries, it is necessary to use high energy and high compaction of active materials, while also increasing the effective space utilization. New problems are often faced when using high energy, high compaction active materials. The electrolyte membrane mainly comprises the following points of 1, reduction of the porosity of a pole piece, slow infiltration speed of electrolyte, reduction of the liquid retention capacity of a battery, 2, incomplete and unstable solid electrolyte membrane (SEI film) formed on the surface of a high-compaction negative electrode, and 3, larger rebound of the pole piece when the compaction is higher, and higher expansion of the circulating thickness of the battery. In addition, the high-energy-density soft-package lithium ion battery improves the space utilization rate as much as possible in structural design, so that the battery is easy to deform in the circulation process in a limited shell space. The formation is used as a key process in the current soft package lithium ion battery production process, and can directly influence the performances of the battery SEI film, such as compactness and stability, self-discharge, consistency, thickness expansion, circulation, multiplying power and the like. The Chinese patent application with publication number of CN110854458A discloses a formation method of a high-voltage soft-package lithium ion battery, mainly through shallow charge and deep discharge of small current, the cycle performance of the method is improved, but SEI film formed by the small current is thicker, the multiplying power performance of a high-energy system can be influenced, the thickness expansion control in the cycle process is not facilitated, and the formation time is long. Therefore, it is necessary to provide a formation method of soft-pack lithium ion batteries with high efficiency and more suitable for high energy density system, so as to further improve the overall performance of the batteries. Disclosure of Invention The invention aims at overcoming the technical defects in the prior art, and provides a rapid formation process of a high-energy-density soft-package lithium ion battery, which can effectively regulate and control the growth speed of an SEI film, improve the liquid retention capacity of the battery, reduce the thickness expansion in the circulating process and further improve the comprehensive performance of the battery. Therefore, the invention provides a rapid formation process of a high-energy-density soft-package lithium ion battery, which comprises three formation stages of first constant current charging, second constant current charging and third constant current discharging, and specifically comprises the following steps: firstly, placing a fully infiltrated battery after liquid injection into clamp formation equipment, and standing the clamped battery to enable the temperature and the pressure of the battery to reach the preset temperature and the pressure of the formation equipment for formation; Step two, carrying out step constant current charging on the battery to 60% -75% of charge state by using a current of 0.05C-2C in three constant current charging modes, and carrying out dormancy and standing; Thirdly, the second constant current charging is carried out to the full-power cut-off voltage of the battery by the current constant current charging of 0.5C-1C, and the battery is dormant and kept stand; fourthly, discharging the third constant current to 55% -65% of the charge state at the current of 0.3C-1C, and cold pressing the battery after the process is finished; wherein in the first step, the clamp formation temperature is 40-85 ℃, the pressure of the single cell surface is controlled to be 0.3-1.4Mpa, the standing time is 1-10min, and the standing time in the second step and the third step is 1-10min; In the second step, the three constant current charging modes are respectively a small current charging mode, a medium current charging mode and a large current charging mode. The charging current of the small current charging system is 0.05C-0.3C, the charging state of charge is less than or equal to 3 percent, the charging current of the medium current charging system is 0.5C-1C, and the charging is carried out to 5 to 10 percent of the charging state, and the charging current of the large current charging system is 1C-2C, and the charging is carried out to 60 to 75 percent of the charging st