A method and device for pre-lithiation of negative pole piece of lithium ion battery

Abstract

The invention provides a pre-lithiation method and device for negative pole pieces of a lithium-ion battery. The method comprises the steps as follows: firstly, the negative pole pieces and metal lithium pieces are sequentially immersed into an electrolyte at intervals in an inert atmosphere condition; the negative pole pieces correspond to the metal lithium pieces one by one but are not in contact with the metal lithium pieces; the negative pole pieces and the metal lithium pieces are connected with a positive electrode and a negative electrode of a power supply through leads respectively; the negative pole pieces are charged; the charging current is 0.05-2.0C; and the negative pole pieces are taken out and dried to obtain the pre-lithiated negative pole pieces. According to the pre-lithiation method and device, 'wet pre-lithiation' is adopted; the cost is low; the production security is high; the pole pieces can be evenly pre-lithiated; and the first efficiency and the energy density of the battery are improved.

Description

technical field [0001] The invention belongs to the technical field of lithium-ion batteries, and in particular relates to a method and a device for performing pre-lithiation of negative pole pieces of lithium-ion batteries. technical background [0002] Lithium-ion batteries are currently the battery system with the highest energy density among commercial secondary batteries. Commercial lithium-ion batteries have good cycleability and safety in use. They have been widely used in communications, transportation, electronic equipment, and industrial products. , and quickly obtain a larger market. [0003] The current important direction of lithium-ion battery development is to further increase the specific energy of the battery, mainly through the optimization of the battery structure and the use of new electrode materials with higher energy density. During the first charging process of the battery, lithium ions are deintercalated from the positive electrode and enter the neg...

AI Technical Summary

Problems solved by technology

Although this method can also play the role of pre-lithiation of the negative electrode sheet, the thickness of the lithium sheet currently available on the market is about 45um, which is far beyond the amount that the negative electrode can absorb. Not only is there too much lithium metal in the battery There are potential safety hazards, and it is also easy to cause lithium precipitation in the cycle

[0009] 4. Deposit a metal lithium layer on the surface of the negative electrode by vacuum evaporation (such as the Japanese patent application of JP2005038720). Although the thickness of the lithium layer can be controlled, in the whole process, it needs to be carried out under a strict vacuum environment. , the evaporation efficiency is also low, and the transfer of subsequent pole pieces needs to prevent nitriding and oxidation, so the process is more complicated and the cost is extremely high

[0010] In view of the above analysis, although the method of adding metal lithium powder and lithium foil to lithium-ion batteries can significantly improve the first-time efficiency of the battery and improve the cycle, etc., and has been verified experimentally, it has not yet been widely promoted.

In addition to the influence of its own safety performance and price, the environmental restrictions and safety factors in the use process are also a major reason for restricting its promotion.

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