title: High-performance rechargeable lithium-iodine batteries using triiodide/iodide redox couples in an aqueous cathode.
abstract: Development of promising battery systems is being intensified to fulfil the needs of long-driving-ranged electric vehicles. The successful candidates for new generation batteries should have higher energy densities than those of currently used batteries and reasonable rechargeability. Here we report that aqueous lithium-iodine batteries based on the triiodide/iodide redox reaction show a high battery performance. By using iodine transformed to triiodide in an aqueous iodide, an aqueous cathode involving the triiodide/iodide redox reaction in a stable potential window avoiding water electrolysis is demonstrated for lithium-iodine batteries. The high solubility of triiodide/iodide redox couples results in an energy density of ~ 0.33 kWh kg(-1), approximately twice that of lithium-ion batteries. The reversible redox reaction without the formation of resistive solid products promotes rechargeability, demonstrating 100 cycles with negligible capacity fading. A low cost, non-flammable and heavy-metal-free aqueous cathode can contribute to the feasibility of scale-up of lithium-iodine batteries for practical energy storage.
authors.affiliation: Advanced Science Institute, Byon Initiative Research Unit (IRU), RIKEN, Hirosawa 2-1, Wako, Saitama 351-0198, Japan.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhao
authors.forename: Lina
authors.initials: L
authors.lastname: Wang
authors.forename: Hye Ryung
authors.initials: HR
authors.lastname: Byon