Integrated Oxygen-Constraining Strategy for Ni-Rich Layered Oxide Cathodes

Abstract

Surface engineering is sought to stabilize nickel-rich layered oxide cathodes in high-energy-density lithium-ion batteries, which suffer from severe surface oxygen loss and rapid structure degradation, especially during deep delithiation at high voltages or high temperatures. Here, we propose a well-designed oxygen-constraining strategy to address the crisis of oxygen evolution. By integrating a La, Fe gradient diffusion layer and a LaFeO₃ coating into the Ni-rich layered particles, along with incorporating an antioxidant binder into the electrodes, three progressive lines of defense are constructed: immobilizing the lattice oxygen at the subsurface, blocking the released oxygen at the interface, and capturing the residual singlet oxygen on the external surface. As a result, effective surface passivation, mitigated bulk and surface degradation, suppressed side reactions, and enhanced electrochemical performance are achieved, far beyond conventional single surface modification. The Ni-rich layered oxide cathodes with integrated oxygen-constraining modifications demonstrate impressive cycling stability in both half-cells and full cells, achieving stable long-term cycling even at a high cutoff voltage of 4.7 V and a high temperature of 45 °C. This work provides a multilevel oxygen-constraining strategy, which can be extended to various layered oxide cathodes involving oxygen release challenges, providing an effective path for the development of high-energy-density lithium-ion batteries.