Eutectic Lithium Salt Sintering-Assisted Ti Substitution Enhances the Electrochemical Performance of LiNi 0.8 Mn 0.2 O ₂ Cathode

Ni-rich layered cathode materials have attracted significant attention due to their higher specific capacity and operating voltage. However, higher cation mixing, serious oxygen release, and irreversible reactions could result in fast capacity decay. This work aims to reduce cation mixing by combining element substitution (Ti substitution) with eutectic lithium salt assistance to prepare Ti-substituted LiNi 0.8 Mn 0.17 Ti 0.03 O 2 (eNMT). The use of Ti substitution and eutectic lithium salt can reduce cation mixing (1.82%), which is lower than that of pure LiNi 0.8 Mn 0.2 O 2 (NM, 5.24%) and only Ti-doped LiNi 0.8 Mn 0.17 Ti 0.03 O 2 (NMT, 3.16%). In addition, eNMT exhibits faster diffusion ability and better structural stability than NM and NMT, as demonstrated by in situ XRD, in situ EIS, and GITT. The eNMT delivers a high specific capacity of 223 mA h g −1 at 0.1C between 2.5 and 4.5 V, which is higher than that of NM (195.7 mA h g −1 ) and NMT (209.1 mA h g −1 ). Even at a high current density of 5C, eNMT still reaches 134.6 mA h g −1 . Furthermore, eNMT also exhibits enhanced cycle stability with a capacity retention of 95% after 100 cycles at 0.5C, higher than NM (88%) and NMT (92%), which shows potential application of Ni-rich layered oxides.