A long cycle‐life high‐voltage spinel lithium‐ion battery electrode achieved by site‐selective doping

Spinel LiNi0.5Mn1.5O4 (LNMO) is a promising cathode candidate for the next-generation high energy-density lithium-ion batteries (LIBs). Unfortunately, the application of LNMO is hindered by its poor cycle stability. Here, we demonstrate an easily-prepared site-selectively doped LNMO electrode with exceptional durability. In this work, Mg is selectively doped onto both tetrahedral (8a) and octahedral (16c) sites in the Fd-3m structure. This site-selective doping not only suppresses unfavorable two-phase reactions and stabilizes the LNMO structure against structural deformation, but also mitigates the dissolution of Mn during cycling. Mg-doped LNMOs exhibit excellent electrochemical performance, retaining ~86% and ~87% of initial capacity after 1500 cycles at 1 C and 2200 cycles at 10 C, respectively. Such excellent electrochemical performance is also reflected in prototype full-batteries with novel TiNb2O7 counter electrodes. This work pioneers an atomic-doping engineering strategy for electrode materials that could be extended to other energy materials to create high-performance devices.