Rich‐Mixed‐Valence NixCo3−xPy Porous Nanowires Interwelded Junction‐Free 3D Network Architectures for Ultrahigh Areal Energy Density Supercapacitors. (27th September 2018)

• Record Type: Journal Article
• Authors: Song, Weijie; Wu, Juan; Wang, Gengjie; Tang, Shaochun; Chen, Gang; Cui, Mingjin; Meng, Xiangkang
• Is Part Of: Advanced functional materials. Volume 28:Number 46(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-09-27
• Subjects: 3D network architectures -- mixed valences -- porous nanowires -- supercapacitors -- transition‐metal phosphides; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.201804620
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: Herein, novel phosphide composites (Ni x Co3 −x P y ) are reported with well‐defined hexagonal thin‐plate morphology and a hieratically porous but robust junction‐free 3D network constructed by interwelding porous NWs, which are achieved by first synthesizing 2D Ni‐Co precursors with tunable Ni/Co molar ratios and top‐down etching, followed by phosphorization. Owing to enhanced electron/ion transfer, increased availability of active sites/interfaces, rich mixed valences of bimetals and P, and strong intercomponent synergy, the optimized NiCoP‐CoP shows a specific capacitance reaching 1969 F g −1, much larger than those of Ni‐Co sulfides and other similar phosphides. An asymmetric supercapacitor employing the advanced NiCoP‐CoP as positive electrode exhibits a remarkable cycling stability with 93% retention after 5000 cycles at 8 A g −1, which is mainly attributed to such architecture allowing strong mechanical stability and to effectively buffer the strain/volume expansion during fast Faradaic reactions. A single device having both an output voltage as high as 7.2 V and an ultrahigh areal energy density of 639 mWh cm −2 at 48 W cm −2 is realized by a designed configuration in which four capacitors in series connection are stacked with solid‐state electrolyte. An almost linear increase in output voltage with the layer number indicates possibility to meet various output requirements for miniaturized electronics. Abstract : Novel rich‐mixed‐valence Ni x Co 3 − x P y has been demonstrated to be excellent pseudocapacitive material, and it can be improved further in energy storage through achieving micrometer‐sized structures with a well‐defined hexagonal thin‐plate morphology and a hieratically porous but robust junction‐free 3D network constructed by interwelding porous nanowires. Optimized NiCoP‐CoP shows higher specific capacitances than those of Ni‐Co sulfides and other similar phosphides.