Enhanced electrocatalytic conversion of tellurium with MnO hollow nanospheres modified hierarchical n-doped carbon nanosheets in high-performance aqueous Zn-Te battery

Abstract

Rechargeable aqueous zinc batteries (AZBs) are increasingly recognized as an alternative to conventional energy storage systems due to their environmentally safe nature, abundant zinc resources, and high theoretical capacity. However, the intercalation or surface redox mechanisms limit the development of AZBs cathode materials due to low specific capacity and energy density. The tellurium-based (Te) materials with conversion mechanisms are promising cathode materials for AZBs. Nevertheless, the slow kinetics are detrimental to the increase in specific capacity and energy density for Zn-Te battery. Therefore, a hierarchical structure of manganese oxide (MnO) hollow nanospheres loaded on nitrogen-doped carbon nanosheets (MnO@NC) was rationally designed and used as Te hosts (Te/MnO@NC) for Zn-Te battery. This hierarchical structure facilitates the loading of more Te species. Meanwhile, the MnO hollow nanospheres can expose more active sites, which can promote the kinetics of Te redox reactions thereby lowering the reaction energy barrier. The Te/MnO@NC cathode exhibits high specific capacity and high energy density (429 mAh g−1 and 407 Wh Kg−1 at 0.1 A g−1). Additionally, the conversion mechanism was investigated by systematic characterization and density functional theory (DFT) calculations. This study presents a new design platform for developing AZBs with high specific capacity and energy density.