Cathode coating using LiInO(2)-LiI composite for stable sulfide-based all-solid-state batteries

All-solid-state batteries with inorganic solid electrolytes are ideal to overcome the safety issues related to the flammable organic electrolyte in lithium ion batteries. Sulfide materials are promising inorganic electrolytes due to their high ionic conductivity and good elasticity. Nevertheless, their application is limited by their high reactivity and instability at the cathode/electrolyte (Li[Ni(0.8)Co(0.15)Al(0.05)]O(2)/75Li(2)S–22P(2)S(5)–3Li(2)SO(4)) interface. In this study, LiInO(2) and LiInO(2)–LiI were introduced as new cathode coating materials to suppress such undesirable reactions. The LiInO(2)–LiI composite coating layer reduced the undesirable interfacial reactions and prevented the diffusion of S and P ions from the sulfide electrolyte to the oxide cathode. Moreover, the electrochemical properties of all-solid-state cells were improved by the cathode coating. The LiInO(2)–LiI-coated electrode presented better rate capability and lower impedance than the pristine and LiInO(2)-coated electrodes. Hence, the LiInO(2)–LiI composite coating was successful at improving the cathode stability while providing superior electrochemical properties.