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 TiP₂O₇ superstructure and report a nanocarbon coating on TiP₂O₇ (TiP₂O₇/C) using layered MXene as a Ti source to realize an effective tuning in the TiO₆ and PO₄ building blocks for boosting the K⁺ diffusion kinetics in PIB. Experimental investigations coupled with systematic theoretical simulations indicate that the interface interaction between TiP₂O₇ and coated nanocarbon could induce internal adjustment in individual Ti-O bonding and relieve the local distortions of TiO₆ octahedra, which endows the TiP₂O₇/C with favorable regulation in a K⁺ hopping manner and significantly reduces the K⁺ diffusion barrier via the diffusion propagation along PO₄ blocks with dominant coordination between O/P and K⁺. Consequently, the TiP₂O₇/C anode could retain 230 mA h g^-1 even after 2200 long-term cycles with an ultralow degradation rate of 0.005%.