Flexible and free-standing La0.33Ti2(PO4)3/C nanofibers film as a novel high-performance anode for sodium- and potassium-ion batteries

Na superionic conductor (NASICON)-type La 0.33 Ti 2 (PO 4 ) 3 (LaTP) is firstly proposed as sodium/potassium storage materials. The density functional theory (DFT) calculations show that LaTP has good electronic character and low Na + /K + migration barriers. The flexible La 0.33 Ti 2 (PO 4 ) 3 /C nanofiber film is synthesized via electrostatic spinning and investigated as free-standing electrode applied to sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) in this work. The low band gap and Na + /K + migration barriers of LaTP, unique morphology, and complete conductive carbon net allow the La 0.33 Ti 2 (PO 4 ) 3 /C nanofibers film to deliver high capacity (296.3 mAh·g −1 for SIBs and 235.8 mAh·g −1 for PIBs), excellent rate performance (142.5 mAh·g −1 for SIBs and 50.5 mAh·g −1 for PIBs at 1.00 A·g −1 ), and superior cyclability above 1000 cycles. The full-cell tests show that the material has a good application prospect, indicating a promising flexible anode material for SIBs and PIBs. Graphical abstract