High-performance rechargeable lithium-iodinebatteries using triiodide/iodide redox couplesin an aqueous cathode

摘要

Development of promising battery systems is being intensified to fulfil the needs oflong-driving-ranged electric vehicles. The successful candidates for new generation batteriesshould have higher energy densities than those of currently used batteries and reasonablerechargeability. Here we report that aqueous lithium-iodine batteries based on the triiodide/iodide redox reaction show a high battery performance. By using iodine transformed totriiodide in an aqueous iodide, an aqueous cathode involving the triiodide/iodideredox reaction in a stable potential window avoiding water electrolysis is demonstrated forlithium-iodine batteries. The high solubility of triiodide/iodide redox couples results in anenergy density of B0.33 kWhkg-1, approximately twice that of lithium-ion batteries. Thereversible redox reaction without the formation of resistive solid products promotesrechargeability, demonstrating 100 cycles with negligible capacity fading. A low cost,non-flammable and heavy-metal-free aqueous cathode can contribute to the feasibilityof scale-up of lithium-iodine batteries for practical energy storage.