Bipolar Redox Molecule-Assembled Freestanding Film Cathodes for Aqueous Zinc-Ion Batteries with Excellent Thermal Adaptivity and Ultralong Life

Organic molecules with high redox potentials and large theoretical capacities are promising cathode materials for aqueous zinc-ion batteries (ZIBs). However, their practical application is hindered by issues of dissolution, low electrical conductivity, and insufficient utilization of active sites. We report herein freestanding film cathodes for high-performance ZIBs with superior charge storage and heat management, wherein a meticulously designed bipolar redox molecule is assembled into a continuous three-dimensional conductive framework of MXene-bonded single-walled carbon nanotubes. The optimal cathode-based coin cells deliver the highest specific capacity of 406.6 mAh g–1 at 0.05 A g–1 and an initial capacity of 219.61 mAh g–1 at 10 A g–1 with extraordinary cycling stability over 60,000 cycles with an average capacity decay of only 2.5 × 10–4% per cycle. Further cycling test at 55 °C and 3 A g–1 reveals an initial capacity of 252.15 mAh g–1 with over 82.75% retention after 3000 cycles and ∼100% coulombic efficiency. Importantly, thermal conductivity and infrared thermal imaging were employed for clear elaboration of temperature evolution dynamics and thermal distribution under different electrode structures. Our work correlating the structure design and thermal management of electrodes provides insights for the rational design of high-performance ZIBs.