基于不同工况下的锂离子电池可用容量预测模型

Prediction model for the available capacity of lithium-ion batteries based on different operating conditions

锂离子电池是诸多设备的主要动力能源,在不同工况下对锂离子电池可用容量的准确预测十分关键。针对目前Peukert方程只能应用于恒温恒流放电情况下可用容量预测的局限性,本工作提出了一种基于不同工况下的锂离子电池可用容量预测优化模型,通过改进Peukert方程并提供合理的系数生成方法,实现了在变温度和倍率条件下对可用容量的准确预测。并通过实验测试了锂电池在不同温度和放电速率下的放电性能,拟合了电池容量保持率与电池平均温度的曲线,使用Arrhenius方程进行分析,通过最小二乘法确定了方程中的参数,根据预测优化模型进行了各种放电情况下的计算,验证了所提出的等效容量方法可以准确预测电池的实际放电容量。最后,利用预测优化模型和实验验证了温度对电池容量的影响,得出当环境温度高于25℃时,电池容量对放电速率的影响较小;当环境温度低于25℃时,温度对电池容量有显著影响,呈现出先下降后随着放电速率增加而增加的趋势的结论,结果说明了电池的平均温度对其容量有较大影响,但高温对电池容量的影响较低温小,需引入温度补偿系数k来考虑平均温度对电池容量的影响。

Lithium-ion batteries(LIBs) are the main power source of many devices;hence,the accurate prediction of their usable capacity under different operating conditions is crucial.In response to the limitations of the current Peukert equation,which can only be applied to predict the available capacity of LIBs under constant temperature and current discharge conditions,this study proposes an optimization model for predicting the available capacity of LIBs under different operating conditions.The accurate prediction of the available capacity of LIBs under variable temperature and rate conditions is realized by improving the Peukert equation and providing a reasonable coefficient generation method.The discharge performance of LIBs at different temperatures and discharge rates is tested through experiments.The curve between the battery capacity retention rate and the average battery temperature is then fitted.The Arrhenius equation is used for the analysis,and the equation parameters are determined using the least squares method.The calculations conducted under various discharge conditions based on the predicted optimization model verify that the proposed equivalent capacity method accurately predicts the battery's actual discharge capacity.Finally,the predictive optimization model and experiments are used to confirm the effect of temperature on the battery capacity.The impact of the battery capacity on the discharge rate is found to be relatively small when the ambient temperature is above 25 ℃.The ambient temperature below 25 ℃ significantly affects the battery capacity,showing a decreasing to increasing trend with the discharge rate increase.The results indicate that the average temperature significantly affects the battery capacity.Moreover,the high temperature has a smaller effect than the low temperature.Therefore,a temperature compensation coefficient k must be introduced to consider the effect of the average temperature on the battery capacity.