High-rate lithium ion battery, aging method and formation method

Abstract

The invention provides a high-rate lithium ion battery, an aging method and a formation method. The effectiveness of pole piece high porosity is characterized in that holdings and wettability of a pole piece electrolyte can be improved, and a conductive agent is compounded to reduce the direct-current internal resistance of a battery; during an aging process, the battery is subjected to high-temperature preheating and softening firstly, then pre-pressing and pressure relief operation are carried out, the battery is shaped, and high-temperature aging can promote uniform infiltration of the electrolyte of a pole piece coating layer; a three-step hot-pressing forming system is adopted, wherein a process step of "high-temperature shelf aging-constant-current discharging-constant-current charging" is executed additionally after the constant-current charging in each step, so that the infiltration effect of the electrolyte can be further improved, and an SEI membrane has sufficient nucleation, growth and reforming time, and by virtue of the charging and discharging cycles, the formation of the SEI membrane on the surfaces of the negative electrode active material particles can be more complete. The lithium ion battery prepared by the method disclosed by the invention is suitable for the fields having relatively high requirements for battery power performance of an unmanned aerial vehicle, an electric tool, a starting and stopping power supply and the like.

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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