磷酸铁锂电池模组老化行为

阐明退役电池的老化行为和衰减机理有助于对其安全高效地再利用。本文采用容量标定、循环老化、材料表面分析等试验方法对一个近似于盲盒的退役电池系统的老化行为进行了研究。研究结果表明，虽然整个退役电池系统是按照容量衰减到80%的做法进行退役，但是退役电池系统中大部分的电池模组SOH值远远高于80%。选取的一个电池模组在设定的2C倍率、100% DOD的老化模式下循环到60% SOH以下只有400次，前200次循环衰减较慢，后200次循环衰减较快。材料表面分析结果发现退役电池在循环老化后阳极的劣化要比阴极的更严重，可循环锂的消耗是导致电池容量衰减的主要原因之一。因此，退役电池梯次利用时从模组级别进行分选和成组，可以最大化地挖掘其剩余价值，同时应尽可能在低电流倍率和浅充浅放等较温和工况下使用退役电池。

Study on aging behavior of lithium iron phosphate battery modules

Clarifying the aging behavior and attenuation mechanism of retired batteries is helpful to reuse them safely and efficiently. In this paper, the aging behavior of a retired battery system similar to a blind box is studied by means of capacity calibration, cycle aging and material surface analysis. The results show that although the whole retired battery system is retired according to the rule of capacity attenuation to 80%, the SOH value of most battery modules in the retired battery system is much higher than 80%. The selected battery module only circulates below 60% SOH for 400 times in the aging mode of 2 C-rate and 100% DOD. The attenuation of the first 200 cycles is slow, and the attenuation of the last 200 cycles is fast. The results of material surface analysis show that the deterioration of anode is more serious than that of cathode after cyclic aging, and the consumption of recyclable lithium is one of the main reasons for the attenuation of battery capacity. Therefore, when the retired batteries are used in echelon, they can be sorted and grouped from the module level to maximize their residual value. At the same time, the retired batteries should be used under mild working conditions such as low current rates and shallow charge and discharge as much as possible.