Group matching method for reducing dynamic voltage difference of power type lithium battery pack

Abstract

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a group matching method for reducing the dynamic voltage difference of a power type lithium battery pack, which comprises the following steps of: S1, performing primary grouping on the capacities of a plurality of single battery cells; S2, placing the single battery cells which are grouped for the first time at normal temperature and normal pressure for 15 days, then measuring a K value, and performing secondary grouping according to the K value; S3, carrying out ACIR and OCV tests on the single battery cells in the S2; S4, grouping the single battery cells in the S3 for three times according to ACIR and OCV; and S5, matching any group of single battery cells in the step S4. According to the invention, a plurality of single battery cells with similar performance are subjected to group matching in a concentrated manner, so that the voltage difference of the battery module at the charging and discharging tail ends is reduced, the capacity conversion rate from the single battery cells to the battery module is improved, the cycle life of the battery module is prolonged, the fault rate of the battery module is reduced, and the production cost is reduced.

Description

technical field [0001] The invention belongs to the technical field of lithium-ion batteries, and in particular relates to a grouping method for reducing the dynamic pressure difference of power-type lithium battery packs. Background technique [0002] As the heart of new energy electric vehicles, ships, industrial vehicles, and base station energy storage, lithium-ion batteries have the advantages of long cycle life, high specific energy, fast charge and discharge, wide operating temperature range, strong adaptability, and environmental protection; Ion batteries are connected in series and in parallel to form battery modules and battery systems. If the stable operation of the lithium-ion battery system is to be guaranteed, the consistency of screening and matching of lithium-ion batteries is one of the key factors. After the existing lithium iron phosphate batteries are grouped, due to certain differences between the individual cells, the modules or systems after the group...

AI Technical Summary

Problems solved by technology

After the existing lithium iron phosphate batteries are grouped, due to certain differences between the individual cells, the modules or systems after the grouping will have different degrees of voltage difference at the end of the charge and discharge, resulting in a change in the conversion rate of the battery pack capacity. Low battery life, poor cycle life, high failure rate of battery packs, etc.

In addition, for the battery packs produced by the existing technology, there is a certain proportion of battery packs that do not meet the pressure difference requirements during the finished product inspection stage; the battery packs with excessive pressure differentials are subsequently milled and dismantled to remove the single cells, and then reworked. This operation is complex and easily scrapped, resulting in high cost

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