Simultaneously constructing solid cathode/anode-electrolyte interphase by anions decomposition in aqueous Zn battery

Aqueous Zn batteries exhibit enormous potential in large-scale energy storage. However, complex interfacial side reactions between electrode and electrolyte fast deteriorate the electrochemical performance. Directly constructing solid electrode-electrolyte interphase is an effective strategy to enhance the interface stability, while it is difficult to form solid electrode-electrolyte interphase in conventional electrolytes. Herein, propylene carbonate was introduced into water-in-salts electrolytes to regulate Zn2+ solvation structure, which reduces the HOMO and LUMO energy gap of Zn2+ solvation complexes. As a result, anion-derived cathode-electrolyte interphase (CEI) and anode-electrolyte interphase (SEI) are formed simultaneously. Assembled Zn||Zn symmetrical cell achieves high cycling stability over 9000 h at 8 mA cm- 2 with 8 mAh cm- 2 . Moreover, Zn||Alx- V2O5 & sdot;nH2O battery displays excellent cycling performance at low current density (capacity retention rate of 92 %/94 % after 400/1300 cycles of 0.2/0.5 A g- 1 ). This work provides a simple and effective strategy to simultaneously construct CEI layer and SEI layer, achieving long life aqueous Zn batteries.