ZnTe/rGO Composite as the Fully Zinced Conversion-Type Cathodes for Aqueous Zinc Ion Batteries

Conversion-type cathodes for aqueous zinc ion batteries (ZIBs) can provide flat plateau slop and stable output potential, compared to general intercalation-type cathodes. The high volumetric capacity and stable output potential of Te make it a promising cathode for ZIBs, but sluggish kinetics and large volume change hinder its further application. To address these issues, we revisit fully zinced ZnTe and construct ZnTe/rGO composites as the new conversion-type cathode. The electrode undergoes a solid-to-solid conversion reaction and shows a stable output potential with ultra-flat discharge plateau slop of 0.09 V (Ah g^-1 )^-1 . When ZnTe is de-zinced and transformed to Te during charge process, it has a volume shrinkage which generates empty space in graphene matrix for latter volume expansion of Te. The graphene matrix also improves conductivity and reaction kinetics of the cathode. Due to the combination of pre-zincation of ZnTe, graphene matrix and the elimination of "shuttle effects" process, ZnTe/rGO electrode exhibits a high and stable capacity of 186 mAh g^-1 at 500 mA g^-1 after 300 cycling, with almost no decay after initial 10 cycles.