Cation-anion synergistic stabilization at the heterointerface for ultra-stable 4.6 V LiCoO2 cathodes

LiCoO₂ (LCO) cathodes suffer from severe interfacial degradation, including cobalt dissolution, oxygen loss, and structural collapse, when cycled at high voltages (> 4.6 V), which limits their practical application. To address this issue, we propose a heterojunction engineering strategy via surface coating with lithium zirconium phosphate (Li₂Zr(PO₄)₂, LZP). The optimized LCO@LZP cathode delivers an ultrahigh initial discharge capacity of 178.1 mAh·g − 1 at 1 C (3.0–4.6 V) and retains 86.3% of its capacity after 200 cycles, significantly outperforming bare LCO (76.0%). It also exhibits enhanced rate capability (108.7 mAh·g − 1 at 10 C) and near-complete capacity recovery (99.7%) upon returning to 0.1 C. Mechanistic studies reveal that the LZP coating stabilizes lattice oxygen through robust Zr–O and P–O bonds, suppresses electrolyte decomposition to form a thin and inorganic-rich cathode electrolyte interphase (CEI), and enhances Li + diffusion kinetics (DLi + = 8.51 × 10 − 12 cm 2 ·s − 1 , 2.4 times higher than bare LCO). DFT calculations further confirm that the LCO/LZP heterojunction reduces oxygen charge compensation and creates an internal electric field that facilitates ion transport while inhibiting electron leakage. This work provides a scalable surface-modification strategy for developing high-energy-density LCO cathodes for next-generation lithium-ion batteries.