Secondary lithium ion battery and electric capacity improving method thereof

Abstract

The invention relates to the technical field of lithium ion batteries, and especially relates to a secondary lithium ion battery, and a method used for improving the electric capacity of the secondary lithium ion battery. The method provided by the invention comprises steps that: an air sac is produced form a polypropylene film, and sufficient electrolyte is filled in the air sac; an inverted U-shaped port of the air sac is extended into a liquid filling hole, and the inverted U-shaped port and the liquid filling hole form a sealed connection; when the secondary lithium ion battery is formed, a liquid filling space in the battery generates gas which is discharged upwards into the air sac; the electrolyte in the air sac flows into the liquid filling space in the battery for supplementing electrolyte consumed by battery formation. With the method provided by the invention, under a condition that a battery housing and a battery core are not changed, the electric capacity is optimized, the capacity attenuation is slow, the circulation performance is good, and the service life is long. With the method, efficiency can be improved, cost can be reduced, and product qualification rate can be ensured.

Description

Technical field: [0001] The invention relates to the technical field of lithium ion batteries, in particular to a secondary lithium ion battery and a method for increasing its capacity. Background technique: [0002] Lithium-ion batteries have the advantages of high voltage, large capacity, long cycle life, no memory effect, light weight, and wide operating range. At present, the market has higher and higher requirements for the performance and capacity of lithium-ion batteries, which not only require the battery to have a high initial capacity, but also require the battery to have a good capacity retention rate in the process of repeated charging and discharging, showing good performance. Has a long service life. The capacity of lithium-ion batteries depends on the selection of raw materials and the utilization rate of the internal space of the battery case. Due to the thicker wall thickness of the battery case, the battery thickness space is relatively reduced. In terms o...

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Problems solved by technology

The capacity of lithium-ion batteries depends on the selection of raw materials and the utilization rate of the internal space of the battery case. Due to the thicker wall thickness of the battery case, the battery thickness space is relatively reduced. In terms of process design, the thickness of the battery core should be controlled to a smaller range. , so it affects the internal space of the entire battery, the volume is small, the liquid injection volume is low, resulting in low capacity, fast capacity decay, poor cycle performance, and low life

In addition, in the prior art, liquid injection in two steps (i.e. refilling liquid after battery formation) is generally used to solve these problems. However, this process not only wastes manpower, reduces efficiency, increases cost, but also affects product qualification. Rate

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