Safety assessment of capacitive lithium-ion batteries under plate compression
This study aimed to investigate the damage and severity of the runaway phenomenon induced by flat compression on capacitive 18650 lithium-ion batteries across different States of Charge(SOC).To achieve this,flat compression tests were conducted on capacitive lithium-ion batteries at five distinct SOC levels using an electronic universal testing machine.The study measured key parameters,including battery surface temperature,open-circuit voltage,and load throughout the compression process.Following each compression,industrial Computed Tomography(CT)scans were performed on the batteries to analyze the internal failure modes.Batteries at different States of Charges(SOCs)were disassembled to measure changes in electrode thickness,isolating the effects of internal pressure variations.The potential safety of battery reuse after each incremental 1 mm of compression was also evaluated.The results revealed that higher SOCs in the batteries corresponded to a more severe heat runaway phenomenon during flat compression.When the battery's SOC exceeded 60％,the peak temperature was observed on the positive electrode side.As the SOC increased,the thickness of the negative electrode also increased continuously,resulting in a higher peak load that ultimately led to battery failure.The compression process of the battery can be categorized into four distinct stages.As the compression depth increased,the internal voids of the battery were progressively compressed.At a depth of 7 mm,both the electrodes and separator fractured,resulting in numerous discharge paths that further intensified internal heat generation.During the third compression stage,the relationship between load and displacement displayed a standard quadratic function,with a fitting degree exceeding 99.95％.Prior to reaching a compression depth of 5 mm,the battery retained approximately 90％of its capacity,while the peak temperature during charging and discharging was around 40℃.Additionally,once the compression exceeded 6 mm,there was a significant increase in peak temperature during charging and discharging,accompanied by an extended duration at constant voltage during charging.This indicates that while the battery poses minimal safety risks under minor deformations,it presents substantial safety hazards with larger deformations(exceeding 7 mm).
safety engineeringlithium ion batteryflat compression testthermorunaway
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维普
