Intralayer/interlayer spatial variation in silicon-doped lithium-rich manganese-based cathode for lattice oxygen fixing

The exceptional capacity of lithium-rich manganese-based oxides (LRMO) primarily originates from the reversible oxygen redox process. Nevertheless, long-term cycling inevitably induces lattice oxygen instability, which remains a critical challenge for the practical application of LRMO. Doping with the oxygen-affinity element silicon (Si) has been identified as a promising strategy for stabilizing lattice oxygen due to the strong Si-O covalent bonds and small ionic radii. The incorporation of robust Si-O covalent bonds and the negative charge on oxygen atoms induced reduction of transition metal slabs intralayer and expansion of transition metal slabs interlayer, thereby fixing lattice oxygen and facilitating the transport of lithium ions in the Li 1.2 Mn 0.53 Co 0.13 Ni 0.13 Si 0.01 O 2 cathode material. Theoretical calculations further demonstrate that the Si substitution strategy substantially increases the formation energy of oxygen vacancies and effectively minimizes lattice oxygen loss under high-voltage conditions (≥ 4.8 V). These findings elucidate the critical role of oxygen-affinity elements with small ionic radii in regulating intralayer/interlayer spatial variations, thereby stabilizing lattice oxygen in high-energy–density electrode materials.