Fast ion diffusion kinetics based on ferroelectric and piezoelectric effect of SnO2/BaTiO3 heterostructures for high-rate sodium storage

Acceleration of reaction kinetics is urgently pursued for high-rate sodium ion batteries, while the utilization of ferroelectric and piezoelectric effect to form local micro electric field to facilitate ion transport has rarely been reported. Herein, a coherent tin oxide/barium titanate heterostructure encapsulated inside nitrogen-doped carbon nanofibers (SnO2/BaTiO3@NCNF) is introduced as sodium ion battery anode, exhibiting high capacity retention (82% over 2000 cycles at 2 A g1) and stunning long-term cyclability (183.4 mAh g1 after 10,000 cycles at 5 A g1). The local potential produced by piezoelectric and ferroelectric effect of BaTiO3 (BTO) can boost sodium ion diffusion kinetics and promote rate performance of SnO2 anode. The piezoelectric effect is initiated from exploiting the drawback of volume expansion of SnO2, while the ferroelectric effect is originated from the charge separation of polarized BTO particles under external electric field. Such principle is instructive for alloying-type and convention-type anodes of alkali-ion batteries.