Tetrathiafulvalene as a sustainable cathode with high rate and Long Life-span for aqueous Zinc-ion battery at low temperatures

Tetrathiafulvalene (TTF) is introduced as a novel and sustainable cathode material for aqueous zinc ion batteries (AZIBs). Based on an anion insertion/desertion reaction, TTF delivers a capacity of 102 mAh g⁻¹ at 1 A g⁻¹ under −20 °C, and obtains a high capacity retention of 96 % after 3500 cycles. Kinetic analysis demonstrates that TTF is more surface-controlled electrochemical process than diffusion-controlled at low temperature. Comprehensive analysis, including ex-situ X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), Raman, Electron Spin-Resonance spectroscopy (ESR) characterization combine with density functional theory (DFT) estimation confirm the high reversibility of the transformation from TTF to TTF⁺ and TTF²⁺, when further increase the charging cut-off voltage to 1.6 V, TTF²⁺ is further oxidized to TTF³⁺. This work not only offers fundamental understanding for reaction mechanism of tetrathiafulvalene and their homologues in battery uses, but also provides a new electrode choice for AZIBs at low temperatures.