New metal redox battery system using hybrid electrolyte

Abstract

Li-aqueous batteries are innovative system that solve problem of traditional aqueous batteries. Aqueous batteries have many merits like safety, economic feasibility, and various cell reaction. However, cell voltage of aqueous batteries are low because electrochemical stability window of H2O is narrow (0~1.23 V vs. SHE). For this reason, aqueous batteries are rarely used and non-aqueous Li-ion batteries are commercialized today. Li-aqueous batteries are new concept that can increase the voltage of aqueous battery. We constructed this Li-aqueous battery system and tested the cell using attractive redox system. Ni2+/Ni(s) redox reaction contain two electron for one transition metal, resulting in large specific capacity. Fe3+/Fe2+ redox reaction has high voltage (3.81 vs. Li+/Li) and iron sources are inexpensive. We also analyzed the cell reaction by XRD, SEM, and GITT analysis. By this new metal redox battery system using hybrid electrolyte, we obtained large capacity of Ni2+/Ni(s) reaction and high voltage of Fe3+/Fe2+ reaction.