Enlocking the high Zn2+-storage of conversion-type Te cathode by regulating the surface binding-interaction with graphene

As a typical conversion-type cathode for aqueous zinc ion batteries (ZIBs), Te cathode exhibits flat platform slope, stable output voltage and high volumetric capacity. However, large volume expansion and low utilization of Te has greatly hampered its commercialization. We tackle these limitations by constructing hierarchical Te-rGO structure with Te nanorods wrapped tightly by a low percentage of graphene to achieve high electrochemical performance. The chemical TeC bond between Te and graphene provides a strong affinity of Te to graphene, making for enhanced conductivity and structural stability of the electrode in the case of over 90% Te content. 1D Te nanorods also facilitate axial charge transfer and adequate use of active material. During cycling, a two-step solid-to-solid conversion reaction mechanism of Te-ZnTe2-ZnTe is proved by ex-situ XRD/XPS/UV–vis, illustrating the elimination of shuttle effects process which is also in favor of intrinsic cycling stability. The three-pronged benefits give Te-rGO cathode a good comprehensive Zn2+ storage performance, with stable output potential, high energy density of 394.4 Wh kg−1 at 28.5 W kg−1 and superb cycling stability with little decay over 2500 cycles at 6 A g−1. Thus, this work gives insights in conversion-type cathodes to make Te-rGO a worthy contender for future commercial aqueous ZIBs.