Three-dimensional hierarchical ternary aerogels of ultrafine TiO2 nanoparticles@porous carbon nanofibers-reduced graphene oxide for high-performance lithium-ion capacitors

A novel three-dimensional hierarchical ternary aerogel of TiO 2 nanoparticles@porous carbon nanofibers-reduced graphene oxide (TiO 2 @PCNF-GA) was designed as an advanced anode for lithium-ion capacitors. TiO 2 @PCNFs were first fabricated by electrospinning assisted by carbonization and a post-etching process, and then assembled into reduced graphene oxide aerogels (GAs) to obtain the TiO 2 @PCNF-GAs. The uniform distribution of the ultrafine TiO 2 nanoparticles in the PCNFs inhibits the aggregation of the TiO 2 nanoparticles. Meanwhile, the interconnected three-dimensional network constructed from the TiO 2 @PCNFs and the GAs inhibits the aggregation of the TiO 2 @PCNFs. Moreover, the hierarchical porous structure of the TiO 2 @PCNF-GAs affords numerous Li-ion transport paths. Therefore, the lithium-ion capacitor composed of the TiO 2 @PCNF-GAs anode and an activated carbon cathode exhibits high energy density versus power density (79.7 Wh kg −1 versus 75 W kg −1 , 15.0 Wh kg −1 versus 15 kW kg −1 ) with superior cycle stability (93.3% retention after 10000 cycles at 5.0 A g −1 ).