The interfacial reactivity and resistance between the cathode and the solid-state electrolyte (SSE) of a solid-state battery (SSB) usually lead to quite poor cycling performance and fast capacity decay. Hence, cathode coatings are generally applied to reduce cathode/SSE interfacial impedance in SSBs. In recent years, based on high-throughput screening, several promising coating materials have been recognized. In the present work, density functional theory (DFT) calculations were conducted on LiH2PO4 and LiTi2(PO4)3 to examine their characteristics as potential cathode coating materials. It was found that both of these materials had high oxidation potentials (>4.5 V), good chemical stability against the electrolyte and the cathode, reasonable ionic conductivity, and wide bandgaps; therefore, they can be used as outstanding cathode coating materials for SSBs.