Microstructure and electrochemical properties of the HT-LiCoO₂/La_2/3–xLi_3xTiO₃ solid electrolyte interfaces

Three different types of HT-LiCoO₂/lithium lanthanum titanate (LLT) assemblies were produced by depositing an HT-LiCoO₂ cathode on polycrystalline LLT with various surface finishes, to investigate the effects of the HT-LiCoO₂/LLT interface structure on the electrochemical properties of the assemblies. An amorphous layer is confirmed to be introduced by Ar ion irradiation to crystalline LLT. The HT-LiCoO₂/LLT assembly composed of the ion-irradiated LLT exhibits good cycle stability and relatively low apparent interface resistivity. These results indicate that the introduction of an amorphous LLT layer by surface modification of crystalline LLT is very effective in improving the structural stability and lithium-ion conductivity of the interface between HT-LiCoO₂ and crystalline LLT.