Facile plasma treated β-MnO2@C hybrids for durable cycling cathodes in aqueous Zn-ion batteries

Abstract

Aqueous zinc-ion batteries have emerged as prospective energy storage devices to partly replace organic ion batteries due to their high safety and eco-friendliness. Providing multifold synthesis methods of cathode materials is essential for Zn-ion battery development. Here, we demonstrated a practical strategy for the large-scale fabrication of high performance β-MnO2@C hybrid cathode materials by plasma assisted milling (P-milling). After P-milling for 10 h, the porous hybrid microparticles consisted of MnO2 nanocrystallites, which combined and wrapped with the thin carbon layer derived from expanded graphite. The pores among the β-MnO2@C particles facilitated electrolyte infiltration during continuous cycling, while combining with carbon greatly enhanced the conductivity of the hybrids and helped to alleviate MnO2 dissolution. Therefore, the β-MnO2@C hybrids delivered excellent cycle stability, with a high capacity of 130 mAh g−1 for 400 cycles at a current rate of 300 mA g−1 in an aqueous Zn(CF3SO3)2 electrolyte. This capacity retention was amongst the highest reported so far for MnO2-based cathode materials for Zn-ion batteries.