Strain engineering by atomic lattice locking in P2-type layered oxide cathode for high-voltage sodium-ion batteries

Developing high-voltage cathode materials is the key to overcome the obstacles of low energy density for sodium-ion batteries (SIBs). P2-type manganese-rich layered oxides are considered as an appealing cathode material for SIBs, but still suffer from severe capacity and voltage decay. As the underlying cause, inhomogeneous interlaminar stress originated from the intrinsic structural transition brings out the generation and propagation of surface cracks, and should be tackled. Herein, we construct an interlocking spinel-like/layered heterostructure via boric acid treatment approach. The well-designed epitaxial spinel-like nanolayer effectively inhibits the unfavorable P2-OP4 phase transition associated with dramatic volume change over 4.1 V, preventing the accumulation of inhomogeneous stress as well as the lattice distortion. The generation and propagation of intragranular cracks are fundamentally prohibited, resulting in improved structural durability and capacity stability. This present work sheds light on the importance of interface engineering of high-voltage cathode materials for SIBs.