General Facet-Controlled Synthesis of Single-Crystalline {010}-Oriented LiMPO4 (M = Mn, Fe, Co) Nanosheets

Facet-controlled synthesis of phospho-olivine (LiMPO4, M = Mn, Fe, Co) cathode materials is of particular interest to manipulate their electrochemical properties because of their anisotropic ionic transport behavior. This study provides a general facet-controlled synthesis of single-crystalline LiMPO4 (M = Mn, Fe, Co) nanosheets with significantly large exposure of (010)-facets, which has not been readily achieved by conventional solution-based coprecipitation or solid-reaction methods. The as-obtained nanosheets show controllable thickness with the thinnest thickness down to 15–20 nm and lateral dimension up to ∼5 μm. Due to the shortened lithium ion diffusion pathway and high ratio of active surface enabled by the thin thickness, the as-prepared LiFePO4 nanosheets, as a model material, demonstrate greatly improved rate capability and cycling stability, with a reversible capacity of ∼80 mA h g–1 at a current rate of 30 C and a stable capacity retention of ∼93% after 500 cycles at a current rate of 5 C. Further electrochemical analysis reveals an enhanced interfacial lithium ion diffusion of the nanosheets, suggesting that facet-controlled 2D LiMPO4 nanosheets are a promising material platform for next-generation high-rate lithium-ion batteries.