Materials Chemistry and Physics, Vol.160, 375-382, 2015
Fabrication of lithium titanate/graphene composites with high rate capability as electrode materials for hybrid electrochemical supercapacitors
A lithium titanate (Li4Ti5O12)/graphene composite (LTO/graphene) is fabricated with a one-pot sol-gel method. Graphite oxide is dispersed in an aqueous solution of lithium acetate and tetrabutyl titanate followed by heat treatment in H-2/Ar. The LTO/graphene composite with reduced aggregation and improved homogeneity is investigated as an anode material for electrochemical capacitors. Electron transport is improved by the conductive graphene network in the insulating Li4Ti5O12 particles. The charge transfer resistance at the particle/electrolyte interface is reduced from 83.1 Omega to 55.4 Omega. The specific capacity of LTO/graphene composite is 126 mAh g(-1) at 20C. The energy density and power density of a hybrid electrochemical supercapacitor with a LTO/graphene negative electrode and an activated carbon positive electrode are 120.8 Wh kg(-1) and 1.5 kW kg(-1), respectively, which is comparable to that of conventional electrochemical double layer capacitors (EDLCs). The LTO/graphene composite fabricated by the one-pot sol-gel method is a promising anode material for hybrid electrochemical supercapacitors. (C) 2015 Elsevier B.V. All rights reserved.