Charging and discharging method for high-capacity retention rate lithium ion battery

Abstract

The invention relates to a charging and discharging method for a high-capacity retention rate lithium ion battery. The method comprises the steps that (1) when the number of turns is n, the lithium ion battery is only charged between the negative electrode and the positive electrode, and control current discharging is carried out between a third electrode and a fourth electrode after charging is completed, wherein the control current is 0.05 to 10A; (2) standing for 1h is carried out, the fourth electrode is connected in parallel with the negative electrode of the lithium ion battery, and thendischarging is performed between the fourth electrode and the positive electrode of the lithium ion battery; (3) for the n+1th turn and subsequent turns, charging and discharging between the positiveand negative electrodes of an ordinary lithium ion battery are used; (4) steps from (1) to (4) are repeated until the next condition number of turns; and (5) after the number of cycles reaches the specified number of turns, the method ends, wherein n is the condition number of turns and is selected from the next turn when the discharge capacity is attenuated every 0.2 to 1%. The charging and discharging method can release active lithium according to the self-demand of each battery core or battery pack, which helps to improve the capacity retention rate.

Description

technical field [0001] The invention relates to the technical field of lithium-ion batteries, in particular to a charging and discharging method for a high-capacity retention lithium-ion battery. Background technique [0002] Lithium-ion battery is a rechargeable battery, which is composed of positive electrode, negative electrode, diaphragm, and electrolyte. The positive and negative electrodes are soaked in the electrolyte. , Li + Intercalation and deintercalation back and forth between two electrodes. When charging, Li + It is deintercalated from the positive electrode, inserted into the negative electrode through the electrolyte, and the negative electrode is in a lithium-rich state; the opposite is true during discharge. [0003] With the gradual increase in the specific energy requirements of power batteries, traditional graphite material negative electrodes can no longer meet the requirements. In the development of 300Wh / kg high specific energy batteries, high nick...

AI Technical Summary

Problems solved by technology

[0003] With the gradual increase in the specific energy requirements of power batteries, traditional graphite material negative electrodes can no longer meet the requirements. In the development of 300Wh / kg high specific energy batteries, high nickel ternary + silicon carbon negative electrode materials will become the mainstream material system of power batteries. Si The theoretical specific capacity of the material is as high as 4200mAh / g, but the volume expansion is as high as 300% during the lithium intercalation process, which will cause cracks in the SEI film formed on the surface of Si particles or other Si-based negative electrodes, resulting in continuous consumption of the electrolyte and positive active lithium.

[0004] Zhejiang Fengli New Energy Technology Co., Ltd. has developed a new type of lithium-ion battery, including a positive pole piece, a negative pole piece, a diaphragm and an electrolyte arranged between the positive pole piece and the negative pole piece, and an electrolyte set on the positive pole piece. The third electrode and the fourth electrode between the sheet and the negative electrode sheet are separated by a single-layer diaphragm, the third electrode is used as a metal lithium negative electrode, and the fourth electrode is used as an activated carbon electrode; but now Some charging methods are usually not supplemented with lithium. For this lithium-ion battery with the addition of a third electrode and a fourth electrode, it is necessary to develop a new matching charging and discharging method.