A novel improvement strategy and a comprehensive mechanism insight for α-MnO2 energy storage in rechargeable aqueous zinc-ion batteries

Abstract

Aqueous zinc-ion batteries have been regarded as the most potential candidate to substitute lithium-ion batteries. However, many serious challenges such as suppressing zinc dendrite growth and undesirable reactions, and achieving fully accepted mechanism also have not been solved. Herein, the commensal composite microspheres with α-MnO₂ nano-wires and carbon nanotubes were achieved and could effectively suppress  ZnSO₄·3Zn(OH)₂·nH₂O rampant crystallization. The electrode assembled with the microspheres delivered a high initial capacity at a current density of 0.05 A g⁻¹ and maintained a significantly prominent capacity retention of 88% over 2500 cycles. Furthermore, a novel energy-storage mechanism, in which multivalent manganese oxides play a synergistic effect, was comprehensively investigated by the quantitative and qualitative analysis for ZnSO₄·3Zn(OH)₂·nH₂O. The capacity contribution of multivalent manganese oxides and the crystal structure dissection in the transformed processes were completely identified. Therefore, our research could provide a novel strategy for designing improved electrode structure and a comprehensive understanding of the energy storage mechanism of α-MnO₂ cathodes.