A high energy and power li-ion capacitor based on a TiO2 nanobelt array anode and a graphene hydrogel cathode

• Main Authors: Wang, Huanwen, Guan, Cao, Wang, Xuefeng, Fan, Hong Jin
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2015
• Subjects: DRNTU::Science::Chemistry::Physical chemistry::Electrochemistry
• Online Access: https://hdl.handle.net/10356/107079; http://hdl.handle.net/10220/25379; http://dx.doi.org/10.1002/smll.201402620
• Institution: Nanyang Technological University

A novel hybrid Li-ion capacitor (LIC) with high energy and power densities is constructed by combining an electrochemical double layer capacitor type cathode (graphene hydrogels) with a Li-ion battery type anode (TiO2 nanobelt arrays). The high power source is provided by the graphene hydrogel cathode, which has a 3D porous network structure and high electrical conductivity, and the counter anode is made of free-standing TiO2 nanobelt arrays (NBA) grown directly on Ti foil without any ancillary materials. Such a subtle designed hybrid Li-ion capacitor allows rapid electron and ion transport in the non-aqueous electrolyte. Within a voltage range of 0.0−3.8 V, a high energy of 82 Wh kg−1 is achieved at a power density of 570 W kg−1. Even at an 8.4 s charge/discharge rate, an energy density as high as 21 Wh kg−1 can be retained. These results demonstrate that the TiO2 NBA//graphene hydrogel LIC exhibits higher energy density than supercapacitors and better power density than Li-ion batteries, which makes it a promising electrochemical power source.