Understanding Origin of Voltage Hysteresis in Conversion Reaction for Na Rechargeable Batteries: The Case of Cobalt Oxides |
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Authors: | Hyunchul Kim Hyungsub Kim Jinsoo Kim Gabin Yoon Kyungmi Lim Won‐Sub Yoon Kisuk Kang |
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Affiliation: | 1. Department of Energy Science, Sungkyunkwan University, Suwon, Republic of Korea;2. Department of Materials Science and Engineering, Research Institute of Advanced Materials (RIAM), Seoul National University, Gwanak‐gu, Seoul, Republic of Korea;3. Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul National University, Seoul, Republic of Korea |
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Abstract: | Conversion reaction electrodes offer a high specific capacity in rechargeable batteries by utilizing wider valence states of transition metals than conventional intercalation‐based electrodes and have thus been intensively studied in recent years as potential electrode materials for high‐energy‐density rechargeable batteries. However, several issues related to conversion reactions remain poorly understood, including the polarization or hysteresis during charge/discharge processes. Herein, Co3O4 in Na cells is taken as an example to understand the aforementioned properties. The large hysteresis in charge/discharge profiles is revealed to be due to different electrochemical reaction paths associated with respective charge and discharge processes, which is attributed to the mobility gap among inter‐diffusing species in a metal oxide compound during de/sodiation. Furthermore, a Co3O4–graphene nanoplatelet hybrid material is demonstrated to be a promising anode for Na rechargeable batteries, delivering a capacity of 756 mAh g?1 with a good reversibility and an energy density of 96 Wh kg?1 (based on the total electrode weight) when combined with a recently reported Na4Fe3(PO4)2(P2O7) cathode. |
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Keywords: | anode material Co3O4 conversion reaction rechargeable battery sodium |
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