Study on thermal runaway of ternary lithium battery overcharge under different charging conditions
To investigate the effects of charging rates and their ad-justments on thermal runaway in ternary lithium batteries under overcharging conditions,the batteries were overcharged to ther-mal runaway at rates of 0.5C,1.0C,and 1.5C,respectively.Ad-ditionally,the charging rate was gradually increased from 0.5C to the point where the battery surface temperature no longer rose,using increments of 0.5C and 0.07C until thermal runaway oc-curred.Results indicate that overcharging at 0.5C does not lead to thermal runaway in a short time span;however,at 1.0C and 1.5C,thermal runaway occurs,with a shorter time to thermal runaway and greater severity at 1.5C.Compared to the 0.5C incre-ment method,increasing the charging rate by 0.07C significantly raises the critical charging rate,reducing the risk of thermal run-away.During the gradual increase with 0.07C,there is a turning point rate:below this rate,the charging rate correlates linearly with the peak temperature;above it,further increases lead to ther-mal runaway.Initiating with 0.5C overcharging followed by rate increments results in lower thermal runaway risks compared to di-rect 1.0C and 1.5C overcharging.Therefore,lower charging rates should be adopted under practical needs,and if rate increases are necessary,gradual increments help mitigate thermal runaway risks.
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