Kinetics enhancement of hierarchical hollow boride microspheres for double-high aqueous Zn-based batteries

The obtained Ni 2 B hollow microsphere (CNB) by a NaBH 4 etching strategy exhibits an ultra-high specific capacity of 2173 F g −1 and the CNB//rGO–Zn battery device presents a dramatic energy density of 454.7 W h kg −1 (power density is 0.46 kW kg −1 ).