CeO2/MnOx@C hollow cathode derived from self-assembly of Ce-Mn-MOFs for high-performance aqueous zinc-ion batteries

Abstract

The construction of composite materials is an effective strategy to solve the problems of poor conductivity, manganese dissolution, and volume expansion of manganese-based materials. Herein, a CeO₂/MnO_x@C hollow composite cathode derived from the self-assembly of Ce-Mn-metal-organic frameworks (Ce-Mn-MOFs) was synthesized. The abundant oxygen vacancies and good electronic/ionic conductivity of CeO₂ improve the electrical conductivity of composite, enhancing the rate performance. The unique hollow structure could inhibit manganese dissolution and alleviate volume expansion. The results indicate that the 1 % CeO₂/MnO_x@C composite cathode possesses a high reversible capacity and excellent cycling stability. Specifically, the 1 % CeO₂/MnO_x@C composite cathode shows a remarkable reversible specific capacity of 130 mAh/g at a current density of 500 mA g^-1, 6.5 times more than the pure MnO_x (20 mAh/g). The capacity retention is up to 99.5 % relative to the initial capacity after 800 cycles. This study provides a new strategy for designing rare-earth composite electrodes to improve electrochemical performance.

Keywords: Aqueous zinc-ion batteries; Ce-Mn-MOFs; CeO(2)/MnO(x)@C; Hollow cathode; Self-assembly.