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Toward a Reversible Mn 4+ /Mn 2+ Redox Reaction and Dendrite‐Free Zn Anode in Near‐Neutral Aqueous Zn/MnO 2 Batteries via Salt Anion Chemistry
Author(s) -
Zeng Xiaohui,
Liu Jiatu,
Mao Jianfeng,
Hao Junnan,
Wang Zhijie,
Zhou Si,
Ling Chris D.,
Guo Zaiping
Publication year - 2020
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201904163
Subject(s) - anode , redox , electrolyte , faraday efficiency , aqueous solution , inorganic chemistry , electrochemistry , materials science , cathode , ion , manganese , stripping (fiber) , salt (chemistry) , chemistry , electrode , organic chemistry , metallurgy , composite material
Rechargeable aqueous Zn/MnO 2 batteries are very attractive large‐scale energy storage technologies, but still suffer from limited cycle life and low capacity. Here the novel adoption of a near‐neutral acetate‐based electrolyte (pH ≈ 6) is presented to promote the two‐electron Mn 4+ /Mn 2+ redox reaction and simultaneously enable a stable Zn anode. The acetate anion triggers a highly reversible MnO 2 /Mn 2+ reaction, which ensures high capacity and avoids the issue of structural collapse of MnO 2 . Meanwhile, the anode‐friendly electrolyte enables a dendrite‐free Zn anode with outstanding stability and high plating/stripping Coulombic efficiency (99.8%). Hence, a high capacity of 556 mA h g −1 , a lifetime of 4000 cycles without decay, and excellent rate capability up to 70 mA cm −2 are demonstated in this new near‐neutral aqueous Zn/MnO 2 battery by simply manipulating the salt anion in the electrolyte. The acetate anion not only modifies the surface properties of MnO 2 cathode but also creates a highly compatible environment for the Zn anode. This work provides a new opportunity for developing high‐performance Zn/MnO 2 and other aqueous batteries based on the salt anion chemistry.