A kind of high-rate lithium-ion battery, aging and formation method

Abstract

The invention provides a high-rate lithium-ion battery, aging and formation methods. The effectiveness of the high porosity of the pole piece lies in the ability to increase the electrolyte retention and wettability of the pole piece. The compounding of the conductive agent is used to reduce the direct current of the battery. Internal resistance; during aging, first preheat and soften the battery at high temperature, and then perform pre-pressurization and pressure relief operations to reshape the battery, and high-temperature aging promotes the uniform infiltration of the electrolyte on the coating layer of the pole piece; a three-step hot-press formation system is adopted , after the completion of each step of constant current charging, adding the "high temperature shelving aging-constant current discharge-constant current charging" step can further improve the wetting effect of the electrolyte and make the SEI film have sufficient nucleation, growth and reformation time , The charge-discharge cycle can make the SEI film on the surface of the negative electrode active material particles more fully formed. The lithium-ion battery prepared by the invention is suitable for fields such as unmanned aerial vehicles, electric tools, start-stop power supplies, etc., which require high battery power performance.

Description

technical field [0001] The invention relates to the technical field of lithium-ion battery manufacturing, in particular to a high-rate lithium-ion battery, aging and formation methods. Background technique [0002] As a new type of clean energy, lithium-ion batteries have the advantages of high working voltage, high energy density, and light weight. They have been widely used in 3C consumer fields, new energy vehicles, and drones. With the continuous expansion of lithium battery application scenarios, the market has a great demand for high-rate and long-life lithium batteries. However, due to the high working current of high-rate lithium-ion batteries, the electrolyte will decompose during use, especially for large-capacity, small-sized and thick batteries. The SEI film is easy to decompose at high temperature, which seriously affects the service life of the battery. [0003] In view of the above problems, Chinese patents (application publication numbers CN 108574115 A, CN...

AI Technical Summary

Problems solved by technology

However, due to the high working current of high-rate lithium-ion batteries, the electrolyte will decompose during use, especially for large-capacity, small-sized and thick batteries. The SEI film is easy to decompose at high temperature, which seriously affects the service life of the battery

[0003] In view of the above problems, Chinese patents (application publication numbers CN 108574115 A, CN 106099202 A) all report a method of forming, in which the battery is pre-pressed and shaped before being formed, and the pre-pressed and shaped are all carried out after aging. The sheet contact is not tight, which is not conducive to the infiltration of electrolyte

Chinese patents (application publication number CN 107579281 A, application publication number CN108306062 A) respectively use the method of fractional injection, multiple standing and vacuum gradient standing to improve the wettability of the electrolyte, but these two methods are external physics. The auxiliary method promotes the wettability of the electrolyte, but does not significantly increase the retention of the electrolyte; it is aged in a hot-pressed fixture, but there is no explanation for the aging pressure system

The disadvantage of the above process is that although the formation of the hot-pressed fixture can make the contact of the pole piece better, the time spent in the formation of the SEI film is short, which is not conducive to the stability of the SEI film structure of the pole piece, and subsequent aging is still required to improve the SEI film. stability

Although this formation scheme can produce a lithium battery with good cycle performance, its disadvantage is that it has a good effect on other small and thin batteries, but it has limited effect on large capacity, small and thick batteries.

In addition, only increasing the residence time of the battery at a specific voltage (cut-off voltage after each precharge) will cause the SEI film on the surface of the wetted and incompletely wetted negative electrode particles to be in different stages, which is not conducive to the formation of a uniform and stable SEI film

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