High Performance Single-Crystal Ni-Rich Cathode Modification via Crystalline LLTO Nanocoating for All-Solid-State Lithium Batteries

Sulfide-based all-solid-state lithium batteries (ASSLBs) assembled with Ni-rich layered cathodes are currently promising candidates for achieving high-energy-density and high-safety energy storage systems. However, the interfacial challenges between sulfide electrolyte and Ni-rich layered cathode, such as space charge layer, side reaction, and poor physical contact, greatly limit the practicality of all-solid-state batteries. In this work, an optimal crystalline Li_0.35La_0.55TiO₃ (LLTO) surface coating with a thickness of roughly 6 nm and a high Li ion conductivity of 0.3 mS cm^-1 was adopted to enhance the structural stability of the single-crystal LiNi_0.6Co_0.2Mn_0.2O₂ (S-NCM622) cathode in ASSLBs. Furthermore, due to the high ionic conductivity and chemical stability of the LLTO coating layer, the interfacial problems, involving interfacial reaction and a space charge layer, in sulfide-based all-solid-state batteries have been effectively solved. As a result, the assembled ASSLBs with the S-NCM622@LLTO cathode exhibit high initial capacity (179.7 mAh g^-1) at 0.05 C and excellent cycling performance with 84.5% capacity retention after 100 cycles at 0.1 C at room temperature. This work proposes an effective strategy to enhance the performance of Ni-rich layered cathodes for next-generation high-energy-density sulfide-based lithium batteries.