A novel high energy hybrid Li-ion capacitor with a three-dimensional hierarchical ternary nanostructure of hydrogen-treated TiO2 nanoparticles/conductive polymer/carbon nanotubes anode and an activated carbon cathode

• Published in: Journal of power sources 2017-07, Vol.355, p.1-7
• Main Authors: Tang, Gang, Cao, Liujun, Xiao, Peng, Zhang, Yunhuai, Liu, Hao
• Format: Article
• Language: English
• Subjects: Hydrogen-treated TiO2 nanoparticles; Li-ion capacitor; Nanostructure; Polypyrrole framework; Single-walled nanotubes; Three-dimension
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2017.04.053

Lithium ion capacitors (LICs) are considered to be high-performance energy storage devices that have stimulated intense attention to bridge the gap between lithium ion battery and supercapacitor. Currently, the major challenge for LICs has been to improve the energy density without sacrificing the high rate of power output performance. Herein, we designed a three-dimensional (3D) hierarchical porous nanostructure of hydrogen-treated TiO2 nanoparticles wrapped conducting polymer polypyrrole (PPy) framework with single-walled carbon nanotubes (SWCNTs) hybrid (denoted as, H-TiO2/PPy/SWCNTs) anode material for LICs through a conventional and green approach. Such a unique network can offer continuous electron transport and reduce the diffusion length of lithium ions. A greatly lithium storage specific capacity is achieved with reversible discharge capacity ∼213 mA h g−1 (based on the mass of TiO2) over 50 cycles (@ 0.1 A g−1), which is almostly three times compared with raw TiO2 (a commercial TiO2 nanoparticles powder). In addition, coupled with commercial activated carbon (AC) cathode, the fully assembled H-TiO2/PPy/SWCNTs//AC LICs delivers a maximum energy and power densities of 31.3 Wh kg−1 and 4 kW kg−1, a reasonably good cycling stability (∼77.8% retention after 3000 cycles) within the voltage range of 1.0–3.0 V. •3D hierarchical nanostructures of H-TiO2/PPy/SWCNTs was designed and synthesized.•Such networks offer a continuous electron transport and short diffusion length of Li+.•A greatly improved lithium storage specific capacity of ∼213 mA h g−1 was achieved.•The LICs showed high energy density and outstanding cycling performance.•The synthesis approach can expand into other iron, cobalt and manganese based oxides.