Method for avoiding blackening of negative electrode pin-flexible connection of lithium ion battery

Abstract

The invention relates to a method for avoiding blackening of a negative electrode pin-flexible connection of a lithium ion battery. The method comprises the following step of pre-charging the lithiumion battery subjected to liquid injection for 30-60 seconds under the condition of 0.5-1 C. Through the pre-charging step, trace water in the electrolyte of the lithium ion battery after liquid injection can be rapidly consumed, the trace water is prevented from reacting with the fluorine-containing lithium salt in the electrolyte to generate sufficient HF, therefore, oxidation of HF to the negative electrode pin-flexible connection in subsequent high-temperature standing and charging and discharging processes is avoided, the effect of avoiding corrosion and blackening of the negative electrode pin-flexible connection of the lithium ion battery is achieved, the DCIR of the lithium ion battery after circulation is reduced, the first effect of the lithium ion battery is improved, and the cycle life of the lithium ion battery is prolonged.

Description

technical field [0001] The invention belongs to the technical field of lithium batteries, and relates to a method for avoiding blackening of a negative electrode pin-soft connection of a lithium ion battery. Background technique [0002] In recent years, lithium-ion batteries have shown good application prospects in the fields of electric vehicles, electric boats, power tools, and energy storage. status; [0003] In lithium-ion batteries, the negative pin-soft connection is generally made of copper. When the cell is formed, the pin-soft connection area often appears black and corroded, accompanied by a tendency to spread. The pin-soft connection is used as a lithium-ion battery The stability or corrosion resistance of important structural components is related to various electrical performance tests of lithium-ion batteries and subsequent use in customer working conditions, affecting the direct current resistance (DCIR) and service life of lithium-ion batteries. [0004] C...

AI Technical Summary

Problems solved by technology

[0004] CN110767941A discloses a method for forming a square lithium-ion battery, which includes the following steps: (1) first place the square lithium-ion battery after a liquid injection in a high-temperature room for a certain period of time, and then use a certain amount of square lithium-ion The batteries are transferred to the formation cabinet as a group at the same time; (2) the formation cabinet is equipped with the same number of suction pipes as a group of square lithium-ion batteries, and all the suction pipes are connected to the vacuum pump in series. The air pipes are respectively aligned with the liquid injection holes of a square lithium-ion battery. After the formation starts, the vacuum pump is started synchronously to carry out negative pressure pumping and pressure maintenance for a group of square lithium-ion batteries at the same time. Charging treatment, and then through high-rate current constant current charging treatment; (3) final rehydration sealing; the above scheme does not consider the problem of corrosion and blackening of the negative pin of the square lithium-ion battery-soft connection and the subsequent impact on electrical performance, in the square lithium-ion battery After the battery is left standing in a high-temperature room after liquid injection and during the subsequent formation process, due to the existence of trace water in the electrolyte, it is easy to react with the electrolyte to form strong oxidizing HF, which corrodes the soft connection pin of the negative electrode, and with the cycle The corrosion and blackening problem has a tendency to further spread and intensify as the frequency increases, which will seriously affect the DCIR performance and cycle life of the prismatic lithium-ion battery after cycling.

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