Summary Tremendous efforts have been made to create significant energy storage devices using nanoscale design and hybrid techniques. Toward this end, herein, we have fabricated, a binder‐free, amorphous iron‐doped nickel‐cobalt phosphate (FexNiCo(PO4)2, ie, F‐NCP) thin film on stainless steel substrate using a facile successive ionic layer adsorption and reaction (SILAR) method. Furthermore, the influence of Fe doping concentration on physico‐chemical properties is investigated. The various F‐NCP‐series electrodes contain nanoparticle‐like morphology that is beneficial for charge transfer and efficient diffusion of electrolytes in supercapacitors. Such nanoparticle‐like morphology and the synergy among iron, cobalt, and nickel elements in the F‐NCP‐3 electrode deliver a maximum specific capacity of 987 C g−1 at a current density of 2.1 A g−1 with excellent cyclic retention of 95.3% after 5000 galvanostatic charge‐discharge cycles. Especially, when an asymmetric solid‐state supercapacitor (ASSS) is fabricated in polyvinyl alcohol‐KOH gel electrolyte with reduced graphene oxide (rGO) as a negative electrode, the designed F‐NCP‐3//rGO ASSS device shows the wide (1.6 V) potential window, and a maximum specific capacitance of 116 F g−1 at 1.5 A g−1. In addition, the ASSS device gives a higher energy density of 41.26 Wh kg−1 at 1.22 kW kg−1 power density and exhibits superior cyclic stability (93% after 5000 cycles). The suggested asymmetric configuration makes a promising alternative of the cathode material to construct energy storage devices for various portable electronic systems.

In this study, the use of exfoliation‐restacking strategy to prepare mesoporous nanohybrids of 2D Nickel‐chromium‐layered double hydroxide (Ni‐Cr‐LDH) nanosheets pillared with polyoxovanadate (POV) anions (Ni‐Cr‐LDH‐POV) for a high‐performance hybrid supercapacitor (HSC) is demonstrated. The pillaring approach of Ni‐Cr‐LDH monolayers with POV anions via exfoliation‐restacking strategy yields mesoporous ordered layered structure with a high surface area and interconnected network morphology. The pillared hybridization of Ni‐Cr‐LDH with POV anions boosts the electrochemical performance of the pristine Ni‐Cr‐LDH, which is attributed to the development of layer‐by‐layer stacking structure with expanded gallery height and high surface area interconnected network morphology. The Ni‐Cr‐LDH‐POV nanohybrid electrode exhibits an improved specific capacity of 294.5 mAh g−1 as compared to pristine Ni‐Cr‐LDH electrode (98.9 mAh g−1) at 1 mA cm−2 with 82% capacity retention after 5000 charge‐discharge cycles. A full‐cell HSC composed of mesoporous Ni‐Cr‐LDH‐POV nanohybrid as a cathode and reduced graphene oxide (rGO) as an anode delivers a maximum specific energy of 57.78 Wh kg−1 and specific power of 1.59 kW kg−1 with 87% cyclic durability over 10 000 charge‐discharge cycles. The present study demonstrates the usefulness of the pillared Ni‐Cr‐LDH‐POV nanohybrids via exfoliation‐restacking strategy for exploring high‐performance HSC.

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Two-dimensional graphene oxide (GO) nanosheets with high electrical conductivity and electrochemical stability are employed as a hybridization matrix to improve the electrode performance of layered double hydroxides (LDHs). A cobaltchromium-LDH hybridized with a GO matrix leads to anchored Co-Cr-LDH-GO (CCG) self-assembly with a high surface area, mesoporous morphology, high electrical conductivity, and high charge transfer kinetics. The CCG nanohybrids display enhanced specific capacity (1502 C g −1 ) with high-rate characteristics compared to pristine Co-Cr-LDH (591 C g −1 ), signifying the crucial role of GO as a hybridization matrix for improving the electrode performance of LDH materials. Aqueous and all-solid-state hybrid supercapacitors are fabricated using the best-optimized CCG nanohybrid and reduced graphene oxide as an anode and a cathode, respectively. The aqueous device delivers a specific capacitance of 181 F g −1 , a specific energy (SE) of 56.66 Wh kg −1 , and a specific power (SP) of 600 W kg −1 at 0.8 A g −1 . Moreover, the solid-state device delivers a specific capacitance of 130.8 F g −1 , a SE of 46.50 Wh kg −1 , and a SP of 1536 W kg −1 at 1.92 A g −1 . The present study clearly demonstrates the usefulness of conducting GO as an efficient hybridization matrix to improve the electrode performance of LDHs.