Regulating the PO₄ and TiO₆ Polyhedral Building Blocks in TiP₂O₇ Boosts the Potassium Ion Diffusion Kinetics

Achieving fast and durable potassiation/depotassiation of anode materials for potassium ion batteries (PIB) still remains an elusive yet fascinating goal. Herein, we challenge the conventional wisdom in synthesizing the TiP 2 O 7 superstructure and report a nanocarbon coating on TiP 2 O 7 (TiP 2 O 7 /C) using layered MXene as a Ti source to realize an effective tuning in the TiO 6 and PO 4 building blocks for boosting the K + diffusion kinetics in PIB. Experimental investigations coupled with systematic theoretical simulations indicate that the interface interaction between TiP 2 O 7 and coated nanocarbon could induce internal adjustment in individual Ti–O bonding and relieve the local distortions of TiO 6 octahedra, which endows the TiP 2 O 7 /C with favorable regulation in a K + hopping manner and significantly reduces the K + diffusion barrier via the diffusion propagation along PO 4 blocks with dominant coordination between O/P and K + . Consequently, the TiP 2 O 7 /C anode could retain 230 mA h g –1 even after 2200 long-term cycles with an ultralow degradation rate of 0.005%.