In Situ 3D Conductive Networks and Interfacial Bonding to Stabilize Oxygen Vacancies for Single-Crystal Ni-Rich Cathodes

Single-crystal nickel-rich LiNi_xCo_yMn_1-x-yO₂ (SCNCM, x ≥ 0.9) has emerged as a promising cathode material for lithium-ion batteries, owing to high energy density and robust crystal structure. However, severe phase transitions contribute to performance degradation and mechanical instability during long-term cycling. To address these challenges, a uniform liquid film strategy is proposed for the in situ construction of a 3D Li_1.3Al_0.1Sc_0.2Ti_1.7(PO₄)₃ (LASTP) conductive network at (003) plane of SCNCM interface. This network establishes an interface bonding—via Sc─O and Al─O bonds—between SCNCM particles and LASTP. The LASTP framework facilitates rapid lithium-ion conduction, while the Sc─O and Al─O bonds stabilize oxygen vacancies, thereby suppressing oxygen evolution and enhancing interfacial structural integrity. This mitigates the irreversible phase transition (especially O3 to O1) and lattice deformation. The feasibility and effectiveness of this 3D network approach are substantiated through a combination of experimental investigations, DFT calculations, BEVL network analysis, and COMSOL simulations. As expected, the pouch-type full battery can achieve a satisfactory capacity retention of 83.7% after 1900 cycles (85.8% at 2.8–4.25 V after 1200 cycles). Furthermore, it provides an extraordinary capacity retention of 79.1% with 161.9 mAh g⁻¹ after 800 cycles in 2.8–4.4 V at 50 °C.