LFP/Graphiteリチウムイオン電池の性能および劣化の予測モデルに関する研究

抄録

The initial degradation behavior of lithium-ion batteries is complicated, and it has been difficult to construct a model that sufficiently matches the capacity change in cycle life tests and calendar life tests under different conditions. In this study, we measured the performance and lifetime of LiFePO₄/Graphite lithium-ion battery and analyzed their electrochemical and degradation characteristics. As a result, we predicted the mechanism as follows. There are two or more phases of side reactions, including reversible reaction that forms the SEI layer and the sequential reaction that produces the non-rechargeable substance. These reactions proceed simultaneously, and each reaction rate changes depending on the electrode potential. In addition, the SEI layer is formed by the former reversible reaction and prevents the diffusion of the deteriorated substance. This model is able to fit to the complicated degrading behavior of the lithium-ion battery.