Method for supplementing lithium to negative pole piece

Abstract

The invention relates to a method for supplementing lithium to a negative pole piece. The method comprises the following specific steps: arranging a first calendering roll, a first composite roll, a second composite roll and a second calendering roll which are adjacently arranged in sequence, and coating silicon oil on roll surfaces of the first calendering roll, the first composite roll, the second composite roll and the second calendering roll; respectively unwinding two lithium strips to enter a gap between the first calendering roll and the first composite roll and a gap between the secondcalendering roll and the second composite roll, carrying out calendering to cause the lithium strips to be attached to the roll surfaces of the first composite roll and the second composite roll; unwinding the negative pole piece to enter a gap between the first composite roll and the second composite roll, and carrying out transfer printing on the lithium strip from the roll surfaces of the first composite roll and the second composite roll to the negative pole piece so as to obtain the lithium-supplemented negative pole piece. The method has the beneficial effects that base strips do not need to be adopted for protecting the lithium strips, so that the operation process of the traditional production process is greatly simplified, the process control difficulty is greatly reduced, the production cost is saved, and meanwhile the thickness accuracy of calendered lithium foils is improved.

Description

technical field [0001] The invention relates to the field of lithium ion batteries, in particular to a method for supplementing lithium with a negative pole piece. Background technique [0002] By supplementing lithium elements on the surface of high-capacity and low-first-efficiency negative electrodes (such as silicon negative electrodes, silicon-carbon negative electrodes, and tin-carbon negative electrodes), the first-time efficiency of lithium-ion batteries containing this negative electrode can be effectively improved and cycle performance can be improved. [0003] From the perspective of battery design, the amount of lithium required is very small. Lithium supplementation through the combination of pure lithium foil and negative electrode often requires pure lithium foil to be only a few microns, which cannot be continuously produced. However, there are also many deficiencies in the existing method for replenishing lithium on the pole piece. For example, in the existi...

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Problems solved by technology

[0003] From the perspective of battery design, the amount of lithium required is very small. Lithium supplementation through the combination of pure lithium foil and negative electrode often requires pure lithium foil to be only a few microns, which cannot be continuously produced.

However, there are also many deficiencies in the existing method for replenishing lithium on the pole piece. For example, in the existing patent CN 105489846 A, the baseband is used to protect the lithium strip, and the lithium strip is rolled onto the baseband, and then transferred from the baseband to the battery pole piece. The process is relatively complicated, and it is difficult to control the accuracy. At the same time, there are still the following problems: 1) Rewinding and unwinding of multiple base tapes is required, and when the base tape is rolled over the rollers for calendering, the base tape is deformed and wrinkled due to inconsistent elastic deformation; 2) There is a deviation in the thickness of the baseband itself, which indirectly expands the thickness tolerance of the rolled lithium foil; 3) The cost of the baseband itself is also relatively high; 4) The requirements for lithium ribbon materials are relatively high

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