Accelerating ion transport via in-situ formation of built-in electric field for fast charging sodium-ion batteries

Batteries with high storage capacity, durable cycle lifetime and fast charging are extremely rare but meaningful. Herein, the three-dimensional core–shell structure with tin dioxide coated barium titanate (BTO) and the outermost layer covered with phosphorus doped carbon ([email protected]2@P-C) is designed as an anode for sodium-ion batteries (SIBs), which shows remarkable cycle tolerance and high-rate sodium storage capacity. It exhibits rapid kinetics at 10 A·g−1 with a powerful life of 10,000 cycles, just 1 min to charge 99%. Such advanced electrochemical performance is primarily attributed to the built-in electric field (BIEF) generated by the in-situ dynamic polarization of BTO from the battery's inherent electric field. Additionally, ensuring the piezoelectric potential through the core–shell structure intensifies the BIEF. The BIEF effectively accelerates sodium ions transport and greatly improves tin dioxide anode reaction kinetics and sodium storage capacity, which is of constructive significance for realizing SIBs with high energy density and fast charging capability.