LaF₃ & LaOF Nanophases Enhance High-Voltage Electrochemical Performance of LiCoO₂

Abstract

LiCoO₂ (LCO) is a widely used cathode material for lithium-ion batteries due to its high specific capacity and good rate capability. However, its practical application at high voltages (≥4.6 V) is severely limited by several critical issues, resulting in poor cycle stability and capacity fading. To address these challenges, LCO with LaF₃ & LaOF nanophases modification was synthesized via a solid-state method, based on a synergetic strategy applying LaF₃ fast-ion-conducting coating to improve the interfacial ionic transport meanwhile constructing corrosion-resistant LaOF to suppress degradation. Through the electrochemical performance tests at high voltages (≥4.65 V), the optimal LCO-0.2LaF possesses superb high-voltage electrochemical performance: the initial capacity equals 193.0 mA·h·g^–1 with the retention of 91.1% after 100 cycles (1 C, 3.0–4.65 V); even at 1 C (3.0–4.70 V) the initial capacity is 207.7 mA·h·g^–1 and the retention is 76.6% after 100 cycles. Structural characterizations, including in-situ XRD, SEM, HRTEM, and XPS, etc., reveal that the synergetic modification of LaF₃ and LaOF nanophases can effectively suppress O^2– peroxidation, Co dissolution and the drastic contraction and expansion of the lattice, thereby inhibiting the irreversible H3 → H1-3 → O1 phase transition above 4.65 V.

Keywords

Lithium-ion battery / LiCoO₂ / LaF₃ / LaOF / High-voltage / Phase transition / Solid-phase synthesis

RIGHTS & PERMISSIONS

2025 SIOC, CAS, Shanghai, & WILEY-VCH GmbH