Journal Article Effect of Potential Profile on Battery Capacity Decrease during Continuous Cycling

荒井, 創  ,  Arai, Hajime  ,  内本, 喜晴  ,  Uchimoto, Yoshiharu

Description
The origin of the capacity decrease of lithium-ion batteries during continuous charge/discharge cycling, astypified by battery operation in electric vehicles, is elucidatedusing LiNi1/3Co1/3Mn1/3O2 (NCM)-based composite electro-des. Electrochemical cycling tests without any rest process showthe capacity decrease only during discharging. Reactiondistribution analysis by operando energy-scanning confocal X-ray diffraction indicates that considerable reaction inhomoge-neity occurs on the lithiation of NCM during discharging,whereas the delithiation during charging proceeds homoge-neously. It is shown that the reaction inhomogeneity caused bylimited Li+ transportation in the composite electrode is relaxedduring charging owing to the potential profile of the NCM-based electrode, whereas no such relaxation occurs during discharging. This result demonstrates that the optimization of the electrode potential profile is important for good cyclability of the batteries in continuous charge/discharge cycling, in addition to improving Li+ transportation within the battery.

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