Search

EP-3923395-B1 - CHARGING AND DISCHARGING METHOD FOR HIGH-CAPACITY RETENTION RATE LITHIUM ION BATTERY

EP3923395B1EP 3923395 B1EP3923395 B1EP 3923395B1EP-3923395-B1

Inventors

  • XU, XIAOXIONG
  • CUI, YANMING
  • HUANG, Yuanqiao
  • GE, Zhimin

Dates

Publication Date
20260506
Application Date
20190622

Claims (6)

  1. Charging and discharging methods of a lithium ion battery with a high capacity retention rate, said lithium ion battery comprising a positive electrode and a negative electrode, and further comprising a third electrode and a fourth electrode for active lithium supplementation, characterized in that the methods comprise a turn operation referring to: a) a cycle including the charging of the negative electrode and positive electrode, and discharging of the third electrode and the fourth electrode; or b) a common charge and discharge cycle including the charging of the negative and positive electrodes, and discharging of the negative and positive electrodes, and in that the methods comprise the following steps: (1) when a number of turns is n, negative and positive electrodes of the lithium ion battery are only charged; after the charging is finished, the third electrode and the fourth electrode are discharged with controlled current, wherein the controlled current is 0.05 - 10 A; (2) after standing for 1 hour, the fourth electrode is connected in parallel with the negative electrode of the lithium ion battery to perform the discharge with the positive electrode of the lithium - ion battery; (3) upon completion of the n turns, common charge and discharge between the positive and negative electrodes of the lithium ion battery occur at the (n + 1) th and subsequent turns; (4) the common charge and discharge are continued until the next conditional number of turns, and steps (1) - (4) are repeated; and (5) when the number of cycles reaches a specified number of turns, the charging and discharging methods are finished; n is a conditional number of turns, which is selected from the next turn every time the discharge capacity is attenuated by 0.2 - 1%.
  2. Charging and discharging methods of the lithium ion battery according to claim 1, wherein: in the step (1), the third electrode is an auxiliary negative electrode, the fourth electrode is an auxiliary positive electrode, and the discharge current is 0.05 - 2 A
  3. Charging and discharging methods of the lithium ion battery according to claim 1, wherein: the discharge cut-off condition in the steps (1) and (2) is preferably a discharge voltage or discharge time.
  4. Charging and discharging methods of the lithium ion battery according to claim 3, wherein: the discharge voltage is 2.3 - 2.9 V.
  5. Charging and discharging methods of the lithium ion battery according to claim 3, wherein: the discharge time is 1 - 30 min.
  6. Charging and discharging methods of the lithium ion battery according to claim 1, wherein: the capacity retention rate of the lithium ion battery is at least 95%.

Description

Technical Field The present invention relates to the technical field of lithium ion batteries, in particular to charging and discharging methods of a lithium ion battery with a high capacity retention rate. Background Art Lithium ion battery is a kind of rechargeable battery, which is composed of a positive electrode, a negative electrode, a separator and an electrolyte. The positive and negative electrodes are immersed in the electrolyte; lithium ions move back and forth between the positive electrode and the negative electrode using the electrolyte as a medium. During the charging and discharging process, Li+ is intercalated and deintercalated back and forth between these two electrodes. When charging, Li+ is deintercalated from the positive electrode and intercalated into the negative electrode via the electrolyte, such that the negative electrode is in a lithium - rich state; the situation is opposite is true when discharging. Document US 2015/263379 discloses an in-situ pre-lithiation process to improve the manufacturing and lifecycle of lithium-ion and lithium-sulfur batteries. With the increasing requirements on the specific energy of a power battery, the traditional graphite negative electrode can no longer meet the requirements. In the development of 300 Wh/kg high specific energy battery, the high nickel ternary + silicon carbon negative electrode material will become the mainstream material system of a power battery. The theoretical specific capacity of a Si material is as high as 4200 mAh/g, but the volume expansion is as high as 300% during lithium intercalation, which will lead to cracks in a SEI film formed on the surface of Si particles or other Si - based negative electrodes, resulting in a continuous consumption of the electrolyte and active lithium in the positive electrode. ZHEJIANG FUNLITHIUM NEW ENERGY TECH CO., LTD has developed a new lithium ion battery, which comprises a positive electrode plate, a negative electrode plate, separators arranged between the positive electrode plate and the negative electrode plate at intervals, and an electrolyte, and further comprises a third electrode and a fourth electrode, which are provided between the positive electrode plate and the negative electrode plate, wherein the third electrode and the fourth electrode are separated by means of a single - layer separator, a metal lithium negative electrode being used as the third electrode, and an activated carbon electrode being used as the fourth electrode. However, the existing ways usually do not include lithium supplementation. With regard to this kind of lithium ion battery with additional third and fourth electrodes, it is necessary to develop new matching charging and discharging methods. Summary of the Invention The present invention is defined in the appended set of claims. The objective of the present invention is to provide charge and discharge methods of a lithium ion battery with a high capacity retention rate, which can be applied to a lithium ion battery with a third/fourth electrode and have the function of timely lithium supplementation. The first objective of the present invention is achieved by the following technical solution: charging and discharging methods of a lithium ion battery with a high capacity retention rate, which comprise the following steps: (1) when a number of turns is n, negative and positive electrodes of the lithium ion battery are only charged; after the charging is finished, a third electrode and a fourth electrode are discharged with controlled current, wherein the controlled current is 0.05 - 10 A;(2) after standing for 1 hour, the fourth electrode is connected in parallel with the negative electrode of the lithium ion battery to perform the discharge with the positive electrode of the lithium - ion battery;(3) common charge and discharge between the positive and negative electrodes of the lithium ion battery occur at the (n + 1) th and subsequent turns;(4) the common charge and discharge are continued until the next conditional number of turns, and steps (1) - (4) are repeated; and(5) when the number of cycles reaches the specified number of turns, the charging and discharging methods are finished;n is the conditional number of turns, which is selected from the next turn every time the discharge capacity is attenuated by 0.2 - 1%. In the prior art, the charging and discharging methods do not include a lithium supplementation process or one - time lithium supplementation process, and the attenuation process of a battery is irreversible. According to the above technical solution, the lithium ion battery of the present application can supplement lithium in time, and when the attenuation condition is found, that is, when the discharge capacity is attenuated by 0.2 - 1%, the positive and negative electrodes can be charged in time; after the charging is finished, the third electrode and the fourth electrode are discharged to realize accurate and quantitative active