PPy-derived carbon nanoparticles anchored on TiO2/C nanofibers as sodium-ion battery anodes with ultra-long cycle stability

• PPy was used as a N-doping carbon source to modify TiO 2 /C nanofibers. • More OVs were introduced in TiO 2 due to the PPy-derived carbon (PC). • The PC nanoparticles improved the cyclic stability of TiO 2 /C nanofibres. As the anode material of sodium-ion batteries (SIBs), TiO 2 exhibits low sodium storage potential and small structural changes in the sodium storage process. To improve the pseudocapacitive behavior of TiO 2 , PPy was used as an N-containing carbon source to modify TiO 2 /C (TC) porous nanofibers. PPy-derived carbon (PC) nanoparticles anchored on TC nanofibers (PCTC) by a simple chemical oxidation method. The PC nanoparticles significantly improved the electrical conductivity of PCTC nanofibers with oxygen vacancies (OVs), while substantially improving the structural stability. As a result, PCTC exhibits a high reversible specific capacity (179.8 mAh g -1 at 1.0 A g -1 ) and a very long cycle life (206.4 mAh g -1 after 1000 cycles at 1.0 A g -1 ) when used as anodes of SIBs. The superior sodium storage performance of PCTC nanofibres is attributed to the special structure with N-doping and OVs, resulting in high pseudo-capacitance contribution (95%, 2.0 mV s -1 ). This OVs-creating approach can improve the pseudocapacitance of oxide anodes for sodium storage.