Method for evaluating self-discharge of lithium ion battery

Abstract

The invention discloses a method for evaluating the self-discharge of a lithium ion battery. The method includes: charging the lithium ion battery to a first state of charge, and circularly charging and discharging the lithium ion battery for first preset time at a first preset temperature; charging the lithium ion battery to a second preset state of charge at a second preset temperature, storingthe lithium ion battery at a third preset temperature, and obtaining the first voltage drop change of the lithium ion battery per unit time during the storage process; repeatedly executing the circulation and the storage operations at least once, and obtaining a second voltage drop change of the lithium ion battery per unit time during each repetitive process; comparing the first voltage drop change and the second voltage drop change, evaluating the self-discharge performance of the lithium ion battery, wherein the first preset temperature is greater than the second preset temperature, and thethird preset temperature is greater than the second preset temperature. According to the technical solution of the present invention, the metal elements in the lithium ion battery are dissolved out by the circular storage at the high temperature, and the evaluation period of the influence of the metal elements on the performance of the battery is shortened.

Description

Technical field [0001] The embodiments of the present invention relate to the technical field of lithium-ion power batteries, and in particular to a method for evaluating self-discharge of lithium-ion batteries. Background technique [0002] Lithium-ion batteries are widely used in electronic equipment and energy fields due to their advantages of high voltage, high energy density, small size, large capacity and long cycle life. This year, with the rapid development of the new energy automobile industry, the safety and consistency of lithium-ion batteries need to be further improved. In the energy storage system and tool market of electric vehicles, a single lithium-ion battery is connected in series or parallel to form a lithium-ion battery pack. Each lithium-ion battery in the lithium-ion battery pack must ensure good self-discharge consistency to ensure charging or There will be no overcharging during storage. [0003] Generally, methods for evaluating the self-discharge of lit...

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Problems solved by technology

[0004] The invention provides a method for evaluating the self-discharge of lithium-ion batteries. By cycling and storing at high temperature, the dissolution process of metal elements in lithium-ion batteries is accelerated, and the lithium-ion batteries are evaluated by comparing the voltage drop changes of lithium-ion batteries per unit time. Excellent self-discharge performance, which solves the problem that it is difficult to identify the influence of the stability of metal elements on the self-discharge performance of lithium-ion batteries, and shortens the evaluation cycle

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