Stabilizing Interfacial Structure of LiCoO2 with Ultrahigh Capacity and Prolonged Cyclability at 4.6V

LiCoO₂ (LCO) cathodes face severe interfacial degradation ( Co/O loss and structural collapse) at high voltages (>4.6 V), limiting their practical deployment. To address this, we propose a heterojunction engineering strategy via surface coating with lithium zirconium phosphate (Li₂Zr(PO₄)₂, LGPO). The optimized LCO@LGPO cathode achieves an ultrahigh initial discharge capacity of 178.1 mAh·g⁻¹ at 1C (3.0–4.6 V) and retains 86.3% capacity after 200 cycles, outperforming bare LCO (76.0%). It also exhibits enhanced rate capability (108.7 mAh·g⁻¹ at 10C) and near-full capacity recovery (99.7%) when returning to 0.1C. Mechanistic studies reveal that the LGPO coating stabilizes lattice oxygen via robust Zr–O/P–O bonds, suppresses electrolyte decomposition to form a thin inorganic-rich CEI layer, and accelerates Li⁺ diffusion kinetics (DLi⁺ = 8.51 × 10⁻¹² cm²·s⁻¹, 2.4× higher than bare LCO). DFT calculations further confirm that the LCO/LGPO heterojunction reduces oxygen charge compensation and creates an internal electric field to facilitate ion transport while blocking electron leakage. This work provides a scalable surface-modification approach to enable high-energy-density LCO cathodes for next-generation batteries.