Surface-to-Bulk Synergistic Modification of Single Crystal Cathode Enables Stable Cycling of Sulfide-Based All-Solid-State Batteries at 4.4 V

The interfacial stability between sulfide solid-state electrolytes (SSEs) and high voltage Ni-rich oxide cathodes is critical to the electrochemical performances of all-solid-state batteries (ASSBs), yet it is challenging to solve the interface issues by surface coating modification. Here, a surface-to-bulk synergistic modification is proposed to achieve a highly stable interface through the combination of TiNb2O7-coated and Ti-doped LiNi0.6Mn0.2Co0.2O2 single crystals (DC-TNO@SCNCM). The TiNb2O7 coating layer with thermodynamic/electrochemical stability and electronic insulation avoids the decomposition of SSEs. The strong Ti-O bond in SCNCM achieved by Ti doping can stabilize lattice oxygen and avoid further electrochemically oxidizing sulfide electrolytes to form oxygenated sulfurous and phosphorous species. The modified DC-TNO@SCNCM cathode exhibits excellent long-cycle stability with a capacity retention rate of 92.2% after 140 cycles at a high cut-off voltage of 4.4 V. This surface-to-bulk synergistic modification strategy provides a new perspective for the design of high-voltage sulfide-based ASSBs.

Automated summary

A surface-to-bulk synergistic modification strategy using TiNb2O7 coating and Ti-doped LiNi0.6Mn0.2Co0.2O2 single crystals was proposed for achieving a highly stable interface in sulfide-based all-solid-state batteries (ASSBs). This modification strategy improved the electrochemical performance and long-cycle stability of the battery by preventing the decomposition of solid-state electrolytes and stabilizing lattice oxygen.