Fabrication of a deliquescent-LiVO3 and LiCoO2 composite electrode for a recoverable all-solid-state lithium ion battery and its electrochemical performance

• Deliquescent-LiVO3 was used as an electrolyte binder for LiCoO2 based cathode.
• LiVO3 and LiCoO2 composite electrode was easily prepared by coating the mixed slurry of LiCoO2 powder and LiVO3 aqueous solution on an Al foil and drying it at 150 °C.
• LiVO3–LiCoO2 composite electrode showed the discharge capacity of 79% for the theoretical capacity.
• The LiVO3 in the composite electrode operated as Li ion conductive paths in the range between 3.0 and 4.25 V.
• Recovery of discharge capacity was found by dissolving the LiVO3 in the composite electrode after cycle test.

The entirely-new concept of forming cathode for all solid state Li ion batteries was advocated. Deliquescent-LiVO3 (LVO) was used as an Li ion conductor in a LiCoO2 (LCO) based cathode. LVO is soluble in water and recrystallizes by drying the LVO aqueous solution. An LVO–LCO composite electrode was easily prepared by coating the mixed slurry of LCO powder and LVO aqueous solution on an Al foil and drying it at 150 °C. Cross-sectional SEM images revealed that the deliquescent LVO intruded the vacancy formed among the LCO particles in the composite electrode. The LVO exhibited Li conductivity and functioned as Li conductive paths among the LCO particles. Superior electrochemical performances of LVO–LCO composite electrode were exhibited by the charge/discharge test and electrochemical impedance spectroscopy (EIS). These performances are attributed to the increase in contact area among the LCO particles and that between cathode electrode and solid electrolyte due to a use of the LVO electrolyte binder. Moreover, a recovery of the discharge capacity was demonstrated by dissolving the LVO in LVO–LCO composite electrode again after the charge/discharge cycle test. In conclusion, the LVO for an electrolyte binder possesses a tremendous advantage in simplification of making an electrode process and forming Li ion conductive paths at the interface among different materials.