Intercalation pseudo-capacitive TiNb2O7 carbon electrode for high-performance lithium ion hybrid electrochemical supercapacitors with ultrahigh energy density

Lithium ion hybrid electrochemical supercapacitors (Li-HESCs) with higher power density than rechargeable batteries and comparative energy density with supercapacitor have been developed recently to meet the practical applications. A novel Li-HESC is designed in this work with TiNb2O7@carbon negative electrode and carbon fibers positive electrode. TiNb207 carbon, a new type lithium ion intercalation pseudo-capacitance electrode, exhibits a capacity of 280 mA h/g at a current density of 0.2 A/g in the potential window of 1.0-3.0 V vs. Li+/Li. Meanwhile, the electrode shows a high specific capacitance of 759 F/g when calculated between 1.0 and 2.0 V vs. Li+/Li at current density of 0.1 A/g. When assembled into a Li-HESC with carbon fiber electrode, an ultrahigh energy density of 110.4 Wh/kg is obtained at power density of 99.58 W/kg, which also remains at 20 W h/kg even under power density of 5464 W/kg, much higher than those of the symmetric supercapacitors based on carbon fibers/ / carbon fibers, CMK-3/ / CMK-3, and some other Li-HESCs, indicating its potential practical applications in hybrid electric vehicles and electric vehicles. (C) 2015 Elsevier Ltd. All rights reserved.