Expansion-induced spontaneous polarization facilitates sodium-ion storage in red phosphorus anode

Red phosphorus (RP), one high theoretical specific capacity (2596 mAh g-1 ) anode material, suffers from severe volume expansion and ion transport lag during charge and discharge process. Herein, barium titanate (BTO) nanoparticles with spontaneous polarization effect are introduced into RP-based composites to suppress the
volume expansion of RP and accelerate the bulk charge transfer. In situ X-ray diffraction technology and Kelvin probe force microscopy synergistically clarify the stress applied to BTO during the RP alloying reaction can effectively increase the dipole moment of BTO, thereby increasing the ion diffusion coefficient of RP-based anode material by approximately 30%. Through the spontaneous polarization effect of BTO, RP-based anode exhibits ultrafast discharging capability, showing the specific capability of 600 mAh g-1 at 10 A g-1. Such efficient strategy of utilizing the spontaneous polarization of piezoelectric materials to improve the bulk charge transport provides a forward-looking idea for the design of highperformance alloying anodes.