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• O-Co x Ni y P was synthesized by the coprecipitation followed by a phosphorization treatment step. • O-Co 1 Ni 4 P electrode containing Co:Ni molar ratio equal to 1:4 showed the best performance. • Optimized content of O dopant in Co x Ni y P is essential for promoting electrochemical reactivity. • The asymmetric supercapacitor displayed outstanding capacitive performance. Tailoring of the electrode microstructure and its active components for the development of high-performance supercapacitors was rather indispensable to advance current technologies. Therefore, we fabricated a novel O-doped Co-Ni nanophosphide (O-Co x Ni y P) with a porous structure. Our approach included the synthesis of 3D Co-Ni precursors with tunable Co/Ni ratio utilizing a phosphorization treatment. Our characterization results indicated that incorporating the optimized O content into Co x Ni y P could tune its electronic structure and yield mixed valences of metals and P, which was beneficial to enhance electrochemical reactivity. The O-Co 1 Ni 4 P-based electrode with the 1:4 Co:Ni molar ratio manifested the best performance as demonstrated by its specific capacity, which was equivalent to 717.1 C/g (at 1 A/g). This value was significantly higher than those of other O-Co x Ni y P family electrodes. The cycling stability of the electrode containing O-Co 1 Ni 4 P as an active material was found to be excellent: it demonstrated a 95.1% capacity retention after 5000 10 A/g cycles. We also assembled an asymmetric supercapacitor containing O-Co 1 Ni 4 P as a positive electrode material and commercial activated carbon as a negative electrode material. The device demonstrated very high energy density (47.5 Wh/kg) and 90.3% capacity retention after 10,000 cycles. These results established that our anion-doping method represented a novel strategy for improving the electrochemical performance of transition metal-based material. These discoveries were useful for energy storage applications. [ABSTRACT FROM AUTHOR]

A novel Ni(OH) 2 /ZnO hydrangea-like structure is prepared via a facile electrodeposition strategy with the Ni(OH) 2 flower-like particles growing on the ZnO layered carrier. This flower-like structure can take advantage of both ZnO and Ni(OH) 2 , leading to a fast ion/electron transport speed and structural stability, finally, attaining an outstanding specific capacitance (2264.55 F g−1 at 0.5 A g−1), excellent rate performance (601.09 F g−1 at 30 A g−1) and cycle stability (maintain 94.9% specific capacitance after 5000 cycles). The Ni-OH/ZnO//AC asymmetric supercapacitor device achieves a high energy density of 68.44 Wh kg−1 at a power density of 400 W kg−1, demonstrating great potential as an electrode material for energy storage devices. The mechanism of synergistic effect of Ni(OH) 2 and ZnO mutually supporting composite structure to improve electrochemical properties is innovatively proposed. • A novel Ni(OH) 2 /ZnO hydrangea-like structure is prepared via electrodeposition. • Outstanding cyclic and rate performance is achieved due to the supporting of ZnO. • The composite fulfills an outstanding capacitance of 2264.55 F g−1 at 0.5 A g−1. • The synergistic effect of mutually supporting structure is discussed in detail. [ABSTRACT FROM AUTHOR]

• The 5% Cu-NCS@FG exhibits mesoporous structure for electrolyte ions diffusion. • A small amount of Cu doping can completely maintain the 3D structure of NCS. • An outstanding rate capability of 86% at 20 times current density can be achieved. • The synergy effect of Cu and FG significantly enhances the electrochemical property. Cu-doped NiCo 2 S 4 /flake graphite nanosheet arrays were prepared by multi-step hydrothermal calcination. Three-dimensional structure provides a wealth of active sites and structure stability to improve the charging/discharging rate. Moreover, 5% Cu-doped NiCo 2 S 4 /flake graphite composite fulfills an excellent specific capacitance of 3080 F·g−1 at 1 A·g−1 and remains 2600 F·g−1 at 20 A·g−1 with an outstanding capacitance retention rate of 86% at 20 times current density. The all-solid supercapacitor with 5% Cu-doped NiCo 2 S 4 /flake graphite electrode and activated carbon electrode exhibits an excellent energy density of 79.4 Wh·g−1 at a power density of 400 W·kg−1 with an outstanding cycling stability of 94% retention after 10000 cycles，suggesting its great potential for the development of high-performance energy storage devices. [ABSTRACT FROM AUTHOR]