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Understanding Origin of Voltage Hysteresis in Conversion Reaction for Na Rechargeable Batteries: The Case of Cobalt Oxides
Author(s) -
Kim Haegyeom,
Kim Hyunchul,
Kim Hyungsub,
Kim Jinsoo,
Yoon Gabin,
Lim Kyungmi,
Yoon WonSub,
Kang Kisuk
Publication year - 2016
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201601357
Subject(s) - materials science , anode , electrode , electrochemistry , intercalation (chemistry) , cathode , oxide , graphene , transition metal , cobalt , hysteresis , cobalt oxide , polarization (electrochemistry) , chemical engineering , self discharge , nanotechnology , inorganic chemistry , chemistry , catalysis , metallurgy , condensed matter physics , biochemistry , physics , electrolyte , engineering
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, Co 3 O 4 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 Co 3 O 4 –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 Na 4 Fe 3 (PO 4 ) 2 (P 2 O 7 ) cathode.