TiO2/carbon nanofibers doped with phosphorus as anodes for hybrid Li-ion capacitors

Hybrid Li-ion capacitors (LICs) are a new kind of electrochemical energy storage device with high energy and power densities. In this work, phosphorus-doped TiO 2 /phosphorus-doped carbon nanofibers (PTO/PC NFs) are fabricated through a simple electrospinning method with disodium hydrogen phosphate as a phosphorus source. Differing from the PTO prepared by hydrothermal method , sol-gel method or calcining treatment at phosphorous atmosphere. The P-doping evenly distributed in PTO/PC NFs and PTO nanoparticles are embedded in PC, which improves the conductivity, structure stability and Li + ions diffusion of TiO 2 . As a result, the PTO/PC NFs anode shows high capacities of 329 and 150 mA h g −1 (0.1 and 2 A g −1 ), long cycle life (201 mA h g −1 after 1000 cycles at 1 A g −1 , 69 mA h g −1 after 1000 cycles at 5 A g −1 ), and superior pseudocapacitance (87%, 2 mV s −1 ). Furthermore, the LICs assembled with PTO/PC NFs anode and AC cathode show outstanding capacity of 35 F g −1 at a current density of 0.1 A g −1 , high energy density of 72 Wh kg −1 at the power density of 250 W kg −1 , and cycle stability (54%, 10 000 cycles, 1 A g −1 ). This suggests that PTO/PC NFs is a potential anode material for high-performance LICs.