Layer by layer: A layered structure K0.5Mn2O4 with oxygen vacancy anchored on a porous carbon framework is synthesized. Benefiting from the synergistic effect of the oxygen vacancies and carbon framework, the efficiency of ion and electron transport is significantly improved, exhibiting excellent electrochemical properties when used as cathode material in aqueous zinc-ion batteries.
High-voltage manganese-based materials are considered as promising cathode materials for aqueous zinc-ion batteries (AZIBs). Herein, oxygen vacancy-rich K0.5Mn2O4 sheets were anchored uniformly onto honeycomb-like interconnected carbon nanoflakes (CNF@K0.5Mn2O4) for AZIB cathode applications. In the composite, the CNFs provided excellent intergranular electron transport capability, while the oxygen vacancies enhanced the electron transport efficiency inside crystals, and the embedded K ions expanded the interlayer spacing and stabilized the layered crystal structure. A reversible specific capacity of 241 mAh g−1 could be maintained by the composite at 0.5 A g−1 for 400 cycles. A combination of ex-situ analytical methods and density functional theory calculations was carried out to elucidate the electrochemical mechanism of reversible zinc storage. In addition, flexible quasi-solid-state batteries of Zn//CNF@K0.5Mn2O4 were constructed by substituting the traditional aqueous electrolyte for a quasi-solid-state gel electrolyte, which worked efficiently and exhibited high bending durability.Zum Volltext