Alternate heterogeneous superlattice control of lattice strain to stabilize Li-rich cathode

Abstract

Li-rich oxides (LROs) working on a synergy of cation and anion redox can deliver greater energy density than that of commercial cathode materials. However, the lattice strain and structural collapse caused by lithium-ion (de)intercalation that accumulate ceaselessly during cycling (especially in a high-voltage region) generate fast decay in performance. We constructed a layered-spinel alternate heterostructure to alleviate the structural evolution of LROs caused by lattice strain. This strategy was achieved with the aid of an anchoring effect from the spinel phase and combination with an Al₂O₃ surface coating to prevent transition-metal dissolution of LROs. These optimized Li-rich materials achieved an initial Coulombic efficiency of ∼100%, high first-cycle specific discharge capacity of 307 mA h g⁻¹, and significantly improved cycle stability with 84% capacity retention after 200 cycles, thereby outperforming most LROs reported previously. Therefore, this synergistic strategy of an alternate heterostructure and surface coating could help to solve the electrochemical decay caused by lattice strain for the commercial application of LROs.