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CN-121978557-A - Screening method and device for self-discharge performance of battery

CN121978557ACN 121978557 ACN121978557 ACN 121978557ACN-121978557-A

Abstract

The invention belongs to the technical field of lithium ion battery manufacturing, and particularly relates to a method and a device for screening self-discharge performance of a battery. The method comprises the steps of sequentially carrying out treatment on the formed battery in each stage, namely, standing in a first temperature section, standing in a second temperature section and standing in a third temperature section, obtaining performance data of the battery before and after treatment in each stage, comparing the performance data of the battery before and after treatment in each stage, and if the variation amplitude of the performance data of the battery before and after treatment in each stage is in a corresponding preset range, the battery is a qualified battery, wherein the temperature of the first temperature section is higher than that of the third temperature section, the temperature of the third temperature section is higher than that of the second temperature section, and the OCV attenuation difference of the abnormal battery is amplified by 3-5 times through high-low temperature alternate standing, so that screening precision is improved, time is saved, and the cycle life of the battery is prolonged.

Inventors

  • LIU GANG

Assignees

  • 合肥国轩高科动力能源有限公司

Dates

Publication Date
20260505
Application Date
20260121

Claims (8)

  1. 1. The screening method for the self-discharge performance of the battery is characterized by comprising the following steps of: Sequentially carrying out the following steps of standing at a first temperature section, standing at a second temperature section and standing at a third temperature section on the battery after formation, and obtaining performance data of the battery before and after the treatment at each step; Comparing the performance data of the batteries before and after each stage of processing, and if the variation amplitude of the performance data of each battery before and after each stage of processing is in a corresponding preset range, determining that the battery is a qualified battery; wherein the temperature of the first temperature section is higher than the temperature of the third temperature section, and the temperature of the third temperature section is higher than the temperature of the second temperature section.
  2. 2. The method for screening self-discharge performance of a battery according to claim 1, wherein said first temperature period of standing comprises standing the battery in an environment of 45-60 ℃ for 12-48 hours.
  3. 3. The method for screening self-discharge performance of a battery according to claim 1, wherein said second temperature section is left standing for 24-72 hours in an environment of 0-10 ℃.
  4. 4. The method for screening self-discharge performance of a battery according to claim 1, wherein said third temperature section is left standing for 8-12 hours in an environment of 20-30 ℃.
  5. 5. The method of claim 1, wherein the battery performance data comprises one or more of open circuit voltage, internal dc resistance, and self-heating temperature of the battery.
  6. 6. The method according to claim 5, wherein the preset range of the amount of change of the open circuit voltage before and after any stage of treatment is 0 to 10mV, and/or the preset range of the rate of change of the direct current internal resistance before and after any stage of treatment is 0 to 5%, and the preset range of the amount of change of the self-heating temperature before and after any stage of treatment is 0 to 2 ℃.
  7. 7. The method according to claim 1, further comprising, when any performance data of the battery at any stage exceeds a corresponding preset range, determining that the battery is not acceptable and eliminating the battery.
  8. 8. A battery self-discharge performance screening apparatus for performing the battery self-discharge performance screening method according to any one of claims 1 to 7, the apparatus comprising: The temperature control unit is used for providing and controlling the standing environments of the first temperature section, the second temperature section and the third temperature section; The testing unit is arranged in the temperature control unit and is used for obtaining performance data of the battery sample before and after standing at each stage; and the processing unit is in communication connection with the testing unit and is used for receiving the performance data before and after each stage of processing, comparing the change of each battery performance data before and after each stage of processing with a corresponding preset range and judging whether the battery sample is qualified or not.

Description

Screening method and device for self-discharge performance of battery Technical Field The invention belongs to the technical field of lithium ion battery manufacturing, and particularly relates to a method and a device for screening self-discharge performance of a battery. Background The lithium ion battery is widely applied in the fields of consumer electronics, electric automobiles, energy storage systems and the like due to the advantages of high energy density, long cycle life and the like. The self-discharge performance of a battery is one of the key indicators for measuring the quality consistency and long-term storage reliability of the battery. Currently, the mainstream screening method for the self-discharge performance of a battery in industrial production mainly depends on a long-time shelf method at normal temperature (usually 20-30 ℃). In the method, after the battery is fully charged, the battery is kept stand for 7 to 15 days in a normal temperature environment, and abnormal batteries are screened by measuring the attenuation rate of Open Circuit Voltage (OCV) before and after the battery is kept stand. However, the method has the obvious defects of overlong screening period, limited screening sensitivity and insignificant difference of electrochemical behaviors of the abnormal battery and the normal battery at normal temperature, and particularly has insufficient identification capability for early micro-short circuit or slow interface side reaction, and is easy to cause missed judgment or misjudgment. In order to shorten the screening time, the industry has attempted to use high temperature acceleration methods, such as placing the battery in an environment above 45 ℃ for a long period of time, while high Wen Shaixuan can accelerate the battery reaction, but easily causes interfacial side reactions. In addition, the existing screening technology mostly only depends on the change rate of a single parameter of the open-circuit voltage as a criterion, and the influence of temperature circulation on the stability of a battery interface is not considered, so that the performance consistency of the screened battery is affected. Disclosure of Invention Aiming at the problems in the prior art, the invention provides a screening method and a screening device for the self-discharge performance of a battery, which can amplify the OCV attenuation difference of an abnormal battery through high-low temperature alternate shelving treatment and efficiently screen the self-discharge performance. In order to achieve the above purpose, the technical scheme provided by the invention is as follows: in a first aspect, the present invention provides a method for screening self-discharge performance of a battery, including: Sequentially carrying out the following steps of standing at a first temperature section, standing at a second temperature section and standing at a third temperature section on the battery after formation, and obtaining performance data of the battery before and after the treatment at each step; Comparing the performance data of the batteries before and after each stage of processing, and if the variation amplitude of the performance data of each battery before and after each stage of processing is in a corresponding preset range, determining that the battery is a qualified battery; wherein the temperature of the first temperature section is higher than the temperature of the third temperature section, and the temperature of the third temperature section is higher than the temperature of the second temperature section. According to the technical scheme, through high-low temperature alternating standing treatment, temperature stress circulation is formed, and self-discharge behavior differences of abnormal batteries can be effectively excited and amplified, so that the sensitivity and the accuracy of screening are remarkably improved. Meanwhile, the time required by the traditional normal-temperature shelf is shortened, and the screening efficiency is improved. Optionally, the first temperature period of standing includes placing the battery in an environment at 45-60 ℃ for 12-48 hours. According to the technical scheme, the battery is placed in a high-temperature environment of 45-60 ℃ for standing for 12-48 hours, so that secondary lithium ion intercalation and interface reaction can be accelerated in a short time, the OCV attenuation of the defective battery is more obvious, meanwhile, the problem of excessive side reaction possibly caused by continuous high temperature is avoided, and the screening speed and the battery safety are both considered. Optionally, the second temperature period of standing includes placing the battery in an environment of 0-10 ℃ for 24-72 hours. According to the technical scheme, after standing at a high temperature, standing is performed in a low-temperature environment of 0-10 ℃ for 24-72 hours, the SEI film structure can be stabilized, and the difference of in