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Inhibiting VOPO 4 ⋅ x H 2 O Decomposition and Dissolution in Rechargeable Aqueous Zinc Batteries to Promote Voltage and Capacity Stabilities
Author(s) -
Shi HuaYu,
Song Yu,
Qin Zengming,
Li Cuicui,
Guo Di,
Liu XiaoXia,
Sun Xiaoqi
Publication year - 2019
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201908853
Subject(s) - electrolyte , dissolution , aqueous solution , cathode , decomposition , electrochemistry , zinc , chemistry , inorganic chemistry , electrode , organic chemistry
VOPO 4 ⋅x H 2 O has been proposed as a cathode for rechargeable aqueous zinc batteries. However, it undergoes significant voltage decay in conventional Zn(OTf) 2 electrolyte. Investigations show the decomposition of VOPO 4 ⋅x H 2 O into VO x in the electrolyte and voltage drops after losing the inductive effect from polyanions.PO 4 3− was thus added to shift the decomposition equilibrium. A high concentration of cheap, highly soluble ZnCl 2 salt in the electrolyte further prevents VOPO 4 ⋅x H 2 O dissolution. The cathode shows stable capacity and voltage retentions in 13 m ZnCl 2 /0.8 m H 3 PO 4 aqueous electrolyte, in direct contrast to that in Zn(OTf) 2 where the decomposition product VO x provides most electrochemical activity over cycling. Sequential H + and Zn 2+ intercalations into the structure are revealed, delivering a high capacity (170 mAh g −1 ). This work shows the potential issue with polyanion cathodes in zinc batteries and proposes an effective solution using fundamental chemical principles.