Enhancing the reaction kinetics and structural stability of high-voltage LiCoO polyanionic species anchoring

Increasing the charging voltage to 4.6 V directly enhances battery capacity and energy density of LiCoO 2 cathodes for lithium-ion batteries. However, issues of the activated harmful phase evolution and surface instability in high-voltage LiCoO 2 lead to dramatic battery capacity decay. Herein, polyanionic PO 4 3− species have been successfully anchored at the surface of LiCoO 2 materials, achieving superior battery performance. The polyanionic species acting as micro funnels at the material surface, could expand LiCoO 2 surface lattice spacing by 10%, contributing to enhanced Li diffusion kinetics and consequent excellent rate performance of 164 mA h g −1 at 20C (1C = 274 mA g −1 ). Crucially, polyanionic species with high electronegativity could stabilize surface oxygen at high voltage by reducing O 2p and Co 3d orbital hybridization, thus suppressing surface Co migration and harmful H1-3 phase formation and leading to superior cycling stability with 84% capacity retention at 1C after 300 cycles. Furthermore, pouch cells containing modified LiCoO 2 and Li metal electrodes deliver an ultra-high energy density of 513 W h kg −1 under high loadings of 32 mg cm −2 . This work provides insightful directions for modifying the material surface structure to obtain high-energy-density cathodes with high-rate performance and long service life. Anchored polyanionic species acting as micro funnels boost the Li + kinetics and enhance the structural stability of high-voltage LiCoO 2 .