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

Abstract

A novel three-dimensional hierarchical ternary aerogel of TiO2 nanoparticles@porous carbon nanofibers-reduced graphene oxide (TiO2@PCNF-GA) was designed as an advanced anode for lithium-ion capacitors. TiO2@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 TiO2@PCNF-GAs. The uniform distribution of the ultrafine TiO2 nanoparticles in the PCNFs inhibits the aggregation of the TiO2 nanoparticles. Meanwhile, the interconnected three-dimensional network constructed from the TiO2@PCNFs and the GAs inhibits the aggregation of the TiO2@PCNFs. Moreover, the hierarchical porous structure of the TiO2@PCNF-GAs affords numerous Li-ion transport paths. Therefore, the lithium-ion capacitor composed of the TiO2@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).