S-Space College of Engineering/Engineering Practice School (공과대학/대학원) Dept. of Material Science and Engineering (재료공학부) Journal Papers (저널논문_재료공학부)
Pre-sodiated nickel cobaltite for high-performance sodium-ion capacitors
- Yang, Dongfang; Sun, Xiaoming; Lim, Kyungmi; Gaddam, Rohit Ranganathan; Kumar, Nanjundan Ashok; Kang, Kisuk; Zhao, Xiu Song
- Issue Date
- Journal of Power Sources, Vol.362, pp.358-365
- Sodium-ion capacitors (NICs) are a hybrid energy storage system that store energy via both charge adsorption at the cathode/electrolyte interface and charge intercalation in the bulk of the anode, thereby possessing a higher energy density than supercapacitors and a higher power density than batteries. In this work, nickel cobaltite (NiCo2O4) hollow spheres with a chestnut shell morphology have been solvothermally synthesized and tested in a sodium half-cell. The NiCo2O4 material exhibits a reversible capacity of 313 mAh g(-1) at 1 A g(-1). Pre-sodiation of NiCo2O4 is found to significantly improve its energy density. A NIC fabricated with pre-sodiated NiCo2O4 as the anode and an activated carbon (AC) as the cathode delivers an energy density of 60 Wh kg(-1) at the power density of 10,000 W kg(-1). Ex-situ X-ray diffraction (XRD) and transmission electron microscopy (TEM) results reveal that NiCo2O4 is converted to metallic nickel and cobalt and Na2O phases during the pre-sodiation. The metallic nickel and cobalt phases are kinetically favourable for the electrolyte diffusion and electrochemical reactions, thus significantly improving the performance of the pre-sodiated NiCo2O4 electrode. (C) 2017 Elsevier B.V. All rights reserved.
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