코발트 산화물 리튬 이온 배터리 용량 및 사이클 안정성에 대한 코발트 산화물/첨가제 계면 및 결정립 크기의 영향

초록

Due to its high theoretical capacity in the conversion reaction, Co3O4, a transition metal oxide, has been attracting attention as an anode material for lithium-ion batteries. Comparing conventional slurry method with the electrophoretic deposition (EPD) method without additives (conductive agents and binders), we investigated the effect of the Co3O4/additive interface and thermal annealing-induced Co3O4 crystallite size on Li-ion battery capacity and cycle stability. The EPD deposition system based on Co3O4 active material without additives was not significantly affected by thermal annealing-induced crystallite size. However, the slurry deposition system in which Co3O4/binder and Co3O4/conductive agent interfaces are embedded showed significant differences in capacity and cycle stability. This result reveals that the Co3O4/additive interface in the slurry system works as a limiting step, depending on the Co3O4 crystallite size, for reversible electrochemical reactions associated with Li-ion battery charging/discharging processes. On the other hand, for the EPD system, the capacity was higher than that in the slurry system with superior cycle stability, indicating that the limiting step was eliminated by removing the Co3O4/additive interface. Moreover, the current collector/active material interface was demonstrated to be crucial in determining the intrinsic electrochemical properties of Co3O4 in the EPD system. Our findings contribute further understanding of the relationship between the battery electrode/additive interface and the electrochemical reaction resulting from the conversion reaction in transition metal oxide electrode materials.

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