Rational Design of Porous Structured Nickel Manganese Sulfides Hexagonal Sheets‐in‐Cage Structures as an Advanced Electrode Material for High‐Performance Electrochemical Capacitors

Abstract

The design of hierarchical electrodes comprising multiple components with a high electrical conductivity and a large specific surface area has been recognized as a feasible strategy to remarkably boost pseudocapacitors. Herein, we delineate hexagonal sheets‐in‐cage shaped nickel–manganese sulfides (Ni‐Mn‐S) with nanosized open spaces for supercapacitor applications to realize faster redox reactions and a lower charge‐transfer resistance with a markedly enhanced specific capacitance. The hybrid was facilely prepared through a two‐step hydrothermal method. Benefiting from the synergistic effect between Ni and Mn active sites with the improvement of both ionic and electric conductivity, the resulting Ni‐Mn‐S hybrid displays a high specific capacitance of 1664 F g−1 at a current density of 1 A g−1 and a capacitance of 785 F g−1 is maintained at a current density of 50 A g−1, revealing an outstanding capacity and rate performance. The asymmetric supercapacitor device assembled with the Ni‐Mn‐S hexagonal sheets‐in‐cage as the positive electrode delivers a maximum energy density of 40.4 Wh kg−1 at a power density of 750 W kg−1. Impressively, the cycling retention of the as‐fabricated device after 10 000 cycles at a current density of 10 A g−1 reaches 85.5 %. Thus, this hybrid with superior capacitive performance holds great potential as an effective charge‐storage material.

Carbon Anchored Epitaxially Grown Nickel Cobalt‐Based Carbonate Hydroxide for Urea Electrooxidation Reaction with a High Activity and Durability

“…Previous reports claimed that the initial oxidation potential of the catalytically active sites matched well with the initial oxidation potential of urea species. Along with this, the most efficient component of Ni‐based catalysts for UOR is NiOOH . Hence, these materials pose an effective opportunity to fabricate robust and low‐cost electrocatalysts for UOR with excellent performances at reduced overpotentials.…”

Role of binary metal chalcogenides in extending the limits of energy storage systems: Challenges and possible solutions

“…Moreover, 1D nanostructures show additional distinct properties of accelerated conduction pathways for both ions and electrons. Many 1D and 2D nanostructured BMCs, including nanobelts [42], nanorods [43][44][45], nanowires [46], and 2D nanosheets/nanoplates [47][48][49][50] have been synthesized using the most common methods such as hydrothermal/solvothermal and chemical solution approaches. As a representative example, a hierarchical iron-cobalt selenide (Fe x Co 3− x Se 4 , 0 ≤ x ≤ 3) with tunable nanostructure and morphology was synthesized by adjusting the stoichiometry ratio of Fe:Co using the most common hydrothermal approach followed by a selenization process [51].…”

“…In this regard, nanostructuring has been approved to develop BMCs to boost capacitive performance. For instance, a nickel manganese sulfide (Ni-Mn-S) hexagonal sheet-in-cage structure with nanosized open spaces was developed to improve redox reactions and decrease charge transfer resistance [49]. The Ni-Mn-S electrode demonstrated a high specific capacitance (1664 F g −1 at 1 A g −1 and 785 F g −1 at 50 A g −1 ) due to the synergistic effect between Mn and Ni electrochemical active sites, and improved electronic/ionic conductivity.…”

Mixed Cu2Se Hexagonal Nanosheets@Co3Se4 Nanospheres for High‐Performance Asymmetric Supercapacitors

“…Transition metal chalcogenides generally possess better capacitance performance than the corresponding oxides due to their higher conductivity and richer redox reactions. [10][11][12] Although the larger atomic mass of selenium leads to a relatively low theoretical gravimetric capacitance of transition metal selenides (TMSs), as a semiconductor element, the conductivity of Se (1 × 10 À 3 S m À 1 ) is much higher than that of S (5 × 10 À 28 S m À 1 ), [13,14] making TMSs still considered as potential electrode materials for energy storage. We noticed that a few reported Cu 2 Se-based electrodes demonstrate high specific capacitance with exceptional rate capability, but undergo comparatively unstable cyclic performance.…”

“…The anions in transition metal compounds also have a significant influence on the performance of the electrodes. Transition metal chalcogenides generally possess better capacitance performance than the corresponding oxides due to their higher conductivity and richer redox reactions [10–12] . Although the larger atomic mass of selenium leads to a relatively low theoretical gravimetric capacitance of transition metal selenides (TMSs), as a semiconductor element, the conductivity of Se (1×10 −3 S m −1 ) is much higher than that of S (5×10 −28 S m −1 ), [13,14] making TMSs still considered as potential electrode materials for energy storage.…”