Constructing Ionic Fast Diffusion Channels on LiNi _0.5 Mn _1.5 O ₄ for Lithium‐Ion Batteries

ABSTRACT Spinel LiNi 0.5 Mn 1.5 O 4 (LNMO) is cobalt‐free and low‐cost cathode material for lithium‐ion batteries (LIBs), offering competitive energy density due to the high operating voltage. However, its practical application is hindered by phase segregation and build‐up impedance from side reactions. Herein, by taking advantage of the good Li + diffusivity of lithiated lanthanum titanate, we introduced a Ti‐assisted surface engineering strategy in which LaTi 2 O 6 (LTO) nano‐islands are in situ constructed on LNMO surfaces, providing additional low‐energy Li + diffusion channels and reinforcing the oxygen framework. Experimental and theoretical analyses demonstrate that Ti plays a dual role by partially incorporating into LNMO bulk, stabilizing the bulk lattice while serving as a precursor for surface LTO formation. Operando synchrotron X‐ray diffraction (XRD) and staircase potential electrochemical impedance spectroscopy (SPEIS) highlight the suppressed phase segregation, mitigated lattice strain and minimized impedance growth upon cycling, respectively. As a result, the as‐designed LNMO delivers a superior rate performance of ∼100 mAh g −1 at 30 C and long‐term cycling stability of 87.8% after 1000 cycles, which is among the best performances reported for LNMO cathodes. A full cell paired with a graphitic carbon anode exhibits significantly enhanced electrochemical performance, offering a promising pathway toward high‐performance manganese‐based LIB applications.