One-step calcination synthesis of interface-coherent crystallized and surface-passivated LiNi_0.5Mn_1.5O₄ for high-voltage lithium-ion battery

LiNi_0.5Mn_1.5O₄ (LNMO) with a spinel crystal structure presents a compelling avenue towards the development of economic cobalt-free and high voltage (~ 5 V) lithium-ion batteries. Nevertheless, the elevated operational voltage of LNMO gives rise to pronounced interfacial interactions between the distorted surface lattices characterized by Jahn–Teller (J–T) distortions and the electrolyte constituents. Herein, a localized crystallized coherent LaNiO₃ and surface passivated Li₃PO₄ layer is deposited on LNMO via a one-step calcination process. As evidenced by transmission electron microscopy (TEM), time-of-flight secondary ion mass spectrometry (ToF-SIMS) and density functional theory (DFT) calculation, the epitaxial growth of LaNiO₃ along the LNMO lattice can effectively stabilize the structure and inhibit irreversible phase transitions, and the Li₃PO₄ surface coating can prevent the chemical reaction between HF and transition metals without sacrificing the electrochemical activity. In addition, the ionic conductive Li₃PO₄ and atomic wetting inter-layer enables fast charge transfer transport property. Consequently, the LNMO material enabled by the lattice bonding and surface passivating features, demonstrates high performance at high current densities and good capacity retention during long-term test. The rational design of interface coherent engineering and surface coating layers of the LNMO cathode material offers a new perspective for the practical application of high-voltage lithium-ion batteries.