Semi‐Metallic Superionic Layers Suppressing Voltage Fading of Li‐Rich Layered Oxide Towards Superior‐Stable Li‐Ion Batteries

Abstract Li‐rich layered oxides (LRLOs) with greater specific capacity density are constrained by voltage attenuation and inferior rate performance because of irreversible oxygen release, metal dissolving and poor lithium‐ion transport capacity. Herein, a simple surface modification is designed to solve the performance degradation and structural collapse of LRLOs. Combining experiments with density functional theory (DFT) calculations, a semi‐metallic LiMn 2 O 4 ‐like structure (LMO) with spin‐polarized conducting electrons, is introduced to the surface of the cathode restrains the activated surficial lattice oxygen ions by its stable oxygen vacancies. Additionally, Ni doping results in a fast‐ion conductor Li 0.8 Nb 0.96 Ni 0.2 O 3 structure (LNO) with lowered lithium ions diffusion barrier, which is tightly conjugating to substrate and synergistically reinforces the Li diffusion path through the cathode‐electrolyte interphase. Moreover, Mn dissolution is successfully relieved due to the decrease in Mn concentration in the coating layers. As a result, the modified material (LRLO@LMO@LNO) exhibits an ultra‐high discharge capacity of 120.4 mAh g −1 even at 10 C with a very small discharge voltage attenuation of 313 mV after 600 cycles (0.52 mV per cycle) at 1 C. Undoubtedly, this method discloses a simple and effective approach to promote the practical utilization of high‐energy‐density.