TiO2‐Coated Interlayer‐Expanded MoSe2/Phosphorus‐Doped Carbon Nanospheres for Ultrafast and Ultralong Cycling Sodium Storage

摘要

Based on multielectron conversion reactions, layered transition metal dichalcogenides are considered promising electrode materials for sodium‐ion batteries, but suffer from poor cycling performance and rate capability due to their low intrinsic conductivity and severe volume variations. Here, interlayer‐expanded MoSe2/phosphorus‐doped carbon hybrid nanospheres coated by anatase TiO2 (denoted as MoSe2/P‐C@TiO2) are prepared by a facile hydrolysis reaction, in which TiO2 coating polypyrrole‐phosphomolybdic acid is utilized as a novel precursor followed by a selenization process. Benefiting from synergistic effects of MoSe2, phosphorus‐doped carbon, and TiO2, the hybrid nanospheres manifest unprecedented cycling stability and ultrafast pseudocapacitive sodium storage capability. The MoSe2/P‐C@TiO2 delivers decent reversible capacities of 214 mAh g⁻¹ at 5.0 A g⁻¹ for 8000 cycles, 154 mAh g⁻¹ at 10.0 A g⁻¹ for 10000 cycles, and an exceptional rate capability up to 20.0 A g⁻¹ with a capacity of ≈175 mAh g⁻¹ in a voltage range of 0.5–3.0 V. Coupled with a Na3V2(PO4)3@C cathode, a full cell successfully confirms a reversible capacity of 242.2 mAh g⁻¹ at 0.5 A g⁻¹ for 100 cycles with a coulombic efficiency over 99%.