Polyaniline / Nickel Ferrite / Nitrogen Doped Graphene Ternary Composite for Supercapacitors

Abstract

Electrode materials are the most important components which greatly affect the capacity, power density and energy density of electrochemical energy storage devices. Lithium ion capacitors combining the advantages of lithium ion battery and supercapacitor, have been widely investigated recently due to their high energy density and high power density [1,2]. Herein, polyaniline / nickel ferrite / nitrogen doped graphene (PNFNG) ternary composite material and nitrogen doped graphene material were prepared by hydrothermal method and in situ polymerization [3]. The specific capacitance of PNFNG is 667 F/g at 0.1A/g in a two-electrode symmetric system tested in KOH aqueous electrolyte. The capacitance loses only 5% after repeating test for 5,000 cycles at a high current density of 5A/g. The energy density of the symmetric supercapacitor can reach 23 Wh/kg at a power density of 28 W/kg. With comparison, a lithium ion hybrid capacitor was assembled with the ternary composite as an anode and activated carbon as a cathode, and the organic electrolyte. The energy density of the hybrid capacitor reaches 104.4 Wh/g when its power density is 300 W/kg at 0.3A/g, respectively. Meanwhile, the capacitance of the hybrid capacitor is 80.3 F/g. The capacitance can keep 72% after 700 cycles at 0.3A/g. Acknowledgements The work was supported by the National Natural Science Foundation of China (Nos. 21073092, 21103092), Program for NCET-12-0629, Ph.D. Program Foundation of Ministry of Education of China (No.20133219110018), the Science and Technology Support Plan (No. BE2013126).