Ultra‑low‑dose Nb2O5 coating promotes electrochemical kinetics and rate capability of Ni-rich oxide cathode

Abstract

LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) cathode material is prized in the electric vehicles (EVs) industry for its high capacity and voltage during operation. However, the high residual alkali content and inferior ionic conductivity of Ni‑rich cathode materials are the intractable obstacles to the large-scale commercial application for a long time. Herein, a feasible Nb₂O₅ coating strategy is proposed to eliminate residual alkali along with constructing high Li⁺ conductive coating layer on NCM811 cathode materials surface. Impressively, 0.3% Nb₂O₅‑coated NCM811 cathode exhibits superior rate capability (146.4 mA h g⁻¹@400 mA g⁻¹) and remarkable rate cyclic stability (188.5 mA h g⁻¹ after 100 cycles with capacity retention of 94.8%). On the one hand, a small quantity of Nb₂O₅ coating on NCM811 surface can react with surface residual alkali to promote the transformation of low electronic conductivity surface residual alkali into the Li⁺ conductor of LiNbO₃ coating layer, enhancing Li⁺ de-intercalation kinetics and rate performance. On the other hand, excessive Nb₂O₅ coating may introduce Nb⁵⁺ into the lattice of NCM811, acting as pivotal components within the Li⁺ layer, which effectively suppresses the H2 ↔ H3 phase transition, contributing to long-term cyclic stability. This work paves a new path for the rational design and facile coating of Ni-rich oxide cathode materials with reinforced structure stability and boosted rate capability in high‑energy‑density lithium-ion batteries.