TiP₂O₇‑Covered Carbon Nanosheets as Anode Materials for Lithium-Ion Batteries with a High Rate and Improved Coulombic Efficiency

The typical polyanionic-based material of TiP₂O₇ can alleviate the volume change caused by repeated insertion/extraction of lithium ions. However, the strong P–O covalent bond leads to sluggish electron transfer kinetics, limiting its rate capability. Here, TiP₂O₇-covered reduced graphene oxide (TiP₂O₇/rGO) is synthesized by facile ball milling and subsequent annealing. The close contact of TiP₂O₇ with rGO accelerates the transfer of electrons and lithium ions, contributing to the reduced interfacial charge transfer impedance and superhigh pseudocapacitance. Therefore, the TiP₂O₇/rGO composite shows excellent rate capability, with capacities of 525.7, 465.3, 427.0, 391.9, 352.8, 286.8, and 172.5 mAh g^–1 at current densities of 0.1, 0.2, 0.5, 1, 2, 5, and 10 A g^–1. The wrapping of rGO nanosheets helps to reduce the irreversible insertion of lithium ions and form a stable solid electrolyte interphase film, which gives the TiP₂O₇/rGO composite a superior initial coulombic efficiency of 61.89% and outstanding cyclic stability with a reversible capacity of 381.2 mAh g^–1 after 1000 cycles at 1 A g^–1. The results suggest an effective strategy for advanced TiP₂O₇-based anodes for lithium-ion batteries.