A tellurium iodide perovskite structure enabling eleven-electron transfer in zinc ion batteries.

The growing potential of low-dimensional metal-halide perovskites as conversion-type cathode materials is limited by electrochemically inert B-site cations, diminishing the battery capacity and energy density. Here, we design a benzyltriethylammonium tellurium iodide perovskite, (BzTEA)TeI, as the cathode material, enabling X- and B-site elements with highly reversible chalcogen- and halogen-related redox reactions, respectively. The engineered perovskite can confine active elements, alleviate the shuttle effect and promote the transfer of Cl on its surface. This allows for the utilization of inert high-valent tellurium cations, eventually realizing a special eleven-electron transfer mode (Te/Te/Te, I/I/I, and Cl/Cl) in suitable electrolytes. The Zn||(BzTEA)TeI battery exhibited a high capacity of up to 473 mAh g and a large energy density of 577 Wh kg at 0.5 A g, with capacity retention up to 82% after 500 cycles at 3 A g. The work sheds light on the design of high-energy batteries utilizing chalcogen-halide perovskite cathodes.