Constructing Ultrahigh-Capacity Zinc−Nickel−Cobalt Oxide@Ni(OH)2 Core−Shell Nanowire Arrays for High-Performance Coaxial Fiber-Shaped Asymmetric Supercapacitors
Qichong Zhang,#,1,3 Weiwei Xu,#,2 Juan Sun,#,1,4 Zhenghui Pan,1 Jingxin Zhao,1 Xiaona Wang,1 Jun Zhang,1 Ping Man,1 Jiabin Guo,1 Zhenyu Zhou,1 Bing He,1 Zengxing Zhang,3 Qingwen Li,1 Yuegang Zhang,1 Lai Xu,*,2 and Yagang Yao*,1
1Division of Advanced Nanomaterials, Key Laboratory of Nanodevices and Applications, CAS Center for Excellence in Nanoscience, Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Suzhou 215123, P. R. China
2Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, 199 Ren’ai Road, Suzhou, Jiangsu 215123, PR China
3Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai 200092, P. R. China
4School of Physical Science and Technology, Shanghai Tech University, Shanghai 200120, PR China
Increased efforts have recently been devoted to developing high-energy-density flexible supercapacitors for their practical application in portable and wearable electronics. Although high operating voltages have been achieved in fiber-shaped asymmetric supercapacitors (FASCs), low specific capacitance still restricts further enhancement of their energy density. This article specifies a facile and cost-effective method to directly grow three-dimensionally well-aligned zinc-nickel-cobalt oxide (ZNCO)@Ni(OH)2 nanowire arrays (NWAs) on carbon nanotube fiber (CNTF) with ultrahigh specific capacitance of 2847.5 F/cm3 (10.678 F/cm2) at a current density of 1 mA/cm2, which is approximately five times higher than that of ZNCO NWAs/CNTF electrode (2.10 F/cm2) and four times of Ni(OH)2/CNTF electrode (2.55 F/cm2). Benefiting from their unique features, we successfully fabricated a prototype coaxial FASC (CFASC) with a maximum operating voltage of 1.6 V, which was assembled by adopting ZNCO@Ni(OH)2 NWAs/CNTF as the core electrode and thin carbon layer coated vanadium nitride (VN@C) NWAs on carbon nanotube strip (CNTS) as the outer electrode with KOH poly(vinyl alcohol) (PVA) as the gel electrolyte. A high specific capacitance of 94.67 F/cm3 (573.75 mF/cm2) and an exceptional energy density of 33.66 mWh/cm3 (204.02 μWh/cm2) were achieved for our CFASC device, which represent the highest level of fiber-shaped supercapacitors to date. More importantly, the fiber-shaped ZnO-based photodetector is powered by the integrated CFASC and it demonstrates excellent sensitivity of detecting UV light. Thus, this work paves the way to construct ultrahigh˗capacity electrode materials for next-generation wearable energy-storage devices.