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Designing excellent electrode materials by establishing superb architectures provides a feasible way to boost the electrochemical properties of supercapacitors (SCs). Herein, a self-supported bimetallic Ni–Fe phosphide (Ni–Fe–P) electrode with a newfangled and multidimensional construction was synthesized by a two-step process. This electrode consists of connective nanosheets which combined numerous interlinked nanoparticles with well-distributed mesopores. By investigating the effects of phosphating temperatures, an optimal phosphide electrode with well-distributed pores throughout the interlaced nanosheets has been obtained. Due to this sophisticated porous structure and the mechanical stability enhanced by the direct growth on binderless Ni foam, the Ni–Fe–P electrode exhibits outstanding electrochemical performance. Density functional theory (DFT) calculations are also performed to demonstrate the increased electrical conductivity and reactivity after the introduction of Fe atoms and phosphorization. Impressively, the fabricated Ni–Fe–P//reduced graphene oxide solid-state SC device delivers an outstanding energy density of 50.2 W h kg−1 at a power density of 800 W kg−1, and remarkable cycle performance (91.5% retention rate after 10 000 cycles). This comprehensive work not only displays a new perspective of the phosphating mechanism at different temperatures but also suggests a versatile approach for engineering promising electrode materials for advanced SCs.

Hollow Zn0.76Co0.24S@N-doped carbon (HZCS@NC) electrode with hierarchical pores structure synthesized by a continuous ingenious method is presented in response of the demand of high-performance supercapacitors. The formation mechanism of the hollow structure, in which the Zn0.76Co0.24S nanoparticles were embedded in a nitrogen-doped carbon layer, was analyzed in this work. This electrode exhibits an excellent specific capacity of 937 C g−1 at 1 A g−1 and a satisfying capacity retention rate of about 112% after 40 000 cycles at a rate of 5 A g−1. Such preeminent performance is realized via (1) the short electrolyte diffusion length caused by the hollow structure, (2) the high electrochemical activities provide by the bimetallic sulfide and heteroatom doping, (3) the efficient combination of faradaic and electrical double layer materials, and (4) the conductive network with multiple holes. The evaluation of electrochemical performance of the assembled HZCS@NC//RGO hybrid supercapacitor (HSC) was also done. Impressively, the HSC gives a satisfactory energy density of 55.47 W h kg−1, a maximum power density of 16.55 kW kg−1, and an ultra-long (100 000) cycling life (108.9% retention of the initial capacity). This study presents a novel strategy for engineering stable poly-porous multicomponent hollow structures for the fabrication of prospective energy storage devices.

A simple method for establishing a class of electrode materials with excellent electrochemical performance for use as supercapacitors is urgently needed. Composite electrode materials, Zn0.76Co0.24S/Co3S4, with different morphologies on three-dimensional nickel foam have been fabricated for the first time using a facile hydrothermal method and successive anion exchange technique. Different surfactants, ammonium fluoride (NH4F) or polyvinylpyrrolidone (PVP), contributed to developing various morphologies, with hexamethylenetetramine (HMT) serving as the alkaline source. The mechanisms of the surfactants that acted on the morphologies of the electrode materials were analyzed by adjusting their ratios. The NH4F actuated flower-like Zn0.76Co0.24S/Co3S4 demonstrated a superior specific capacitance of 2798.16 F g−1 at 5 mA cm−2 and retained outstanding cyclic stability of 93.8% after 7000 cycles, compared to the grass-like Zn0.76Co0.24S/Co3S4 actuated by PVP. The assembly of the all-solid-state asymmetric supercapacitor (ASC), flower-like Zn0.76Co0.24S/Co3S4//RGO, resulted in a high energy density of about 62.22 W h kg−1 and a maximum power density of 16 kW kg−1, as well as a long cycle life (86.3% of capacity retention after 8000 cycles). This comprehensive study on the control of the morphologies of transition metal sulfide composites by surfactants provides a general method to synthesize multicomponent electrode materials for energy storage devices.

Red phosphorus (P) has been regarded as an attractive anode material in a sodium-ion battery (SIB) due to its natural abundance and higher theoretical specific capacity. We developed a novel flexible P/carbon nanofibers@reduced graphene oxide (P/CFs@RGO) electrode for sodium-ion batteries through simple vapor-redistribution and electrospinning. In this multi-layer structured P/CFs@RGO electrode, the large volume changes of the red P layer during cycling can be easily buffered and the loss of P from carbon fibers is prevented. In addition, the electrodes have better electron transport. As the result, the as-prepared P/CFs@RGO electrode delivers a high capacity retention of 725.9 mA h g−1 after 55 cycles at 50 mA g−1 and a significant capacity of 406.6 mA h g−1 even at large current densities of 1000 mA g−1 after 180 cycles.