Rational design of ZnO-based aqueous batteries for safe, fast, and reliable energy storage: Accomplishment of stable K+ storage/release

•A new rechargeable and stable Zn-based aqueous system with high discharge voltage of 2.3 V is assembled.•K+-based SEI can be formed; Zn dendrite and active material dissolution can be effectively inhibited.•A high capacity of 640 mAh/g with CE of 97.3 % at 4–8 A g−1 is achieved.•Reversible K+ storage/release mechanism dominates the voltage and the capacity.