磷酸铁锂电池循环寿命衰减和寿命预测

Cycle fading of LiFePO_(4) lithium-ion battery and its life prediction

通过测试磷酸铁锂电池在不同温度下的循环衰减曲线,研究其衰减特点和规律,得到电池存在最优循环温度区间,同时运用dV/dQ-Q曲线分解衰减来源。在总容量衰减达到20%后,其主要衰减来源于活性锂的损失,占总损失的80%以上;其次为负极材质的损失约为12%~14%,而正极磷酸铁锂的材质损失约为4%~6%。该结果为长循环寿命磷酸铁锂电池的设计和改善方向提供了理论依据。同时运用温度加速对电芯循环寿命衰减进行寿命拟合和寿命预测,在特定的温度区间内具有较好的预测准确性。

Capacity fading of LiFePO^(4)/graphite(LFP)cell was investigated at different temperatures and an optimal cycling temperature range was found for this type of battery.Also,by using dV/dQ-Q curve,it is found that when capacity loss is 20%of its initial value,the main factor is the loss of active lithium(LLI),which occupies more than 80%of the total loss.The loss of anode material is between 12%and 14%and the loss of cathode material was about 4%-6%.This result provides a theoretical basis for designing and improving of cycle performance of LFP battery.Further,the cycle life was fitted and could be predicted by using temperature acceleration model.And the prediction model is very accurate in the specific temperature range.