Cathode of Zn-Ni Layered Double Hydroxide Nanosheet Arrays Wrapped with a Porous NiMoS_x Shell and Anode of 3D Hierarchical Nitrogen-Doped Carbon for High-Performance Asymmetric Supercapacitors

Abstract

The rational design and synthesis of multicomponent core@shell structures with fine morphology is a promising approach to develop electrode materials for advanced supercapacitors. In this study, Zn-Ni LDH@NiMoS x nanosheets with a hierarchical heterostructure are grown in situ on nickel foam through the hydrothermal routes, for the potential use as an integrated positive electrode material. The Zn-Ni LDH@NiMoS x shows a unique morphology and mesoporous feature with excellent synergistic effects between individual components. Compared to the single components of Zn-Ni LDH and NiMoS x , the Zn-Ni LDH@NiMoS x nanosheet arrays show better specific capacity (357.88 mA h g–1 at a current of 5 mA cm–2) and rate performance. Meanwhile, ZIF-8 derived 3D nanoporous N-doped carbon (ZPNC) material is used as an negative electrode material with high surface area (918.3 m2 g–1), excellent capacity (52.42 mA h g–1 at 2 mA cm–2), and rate performance (∼55% at 50 mA cm–2). The asymmetric supercapacitor device based on Zn-Ni LDH@NiMoS x and ZPNC electrodes exhibits a specific capacity of 73.18 mA h g–1 at 3.5 mA cm–2 and an excellent cycle lifespan of 90% after 6000 cycles. The device also demonstrates excellent energy density (58.54 W h kg–1) and very high power density (7397.34 W kg–1).

Experimental and Theoretical Insights of Anion Regulation in MOF-Derived Ni–Co-Based Nanosheets for Supercapacitors and Anion Exchange Membrane Water Electrolyzers

“…The additional signal positioned at ∼169.0 eV is ascribed to surface sulfate groups. 8,17 The P 2p spectrum (Figure 4i) of Ni−Co−P NAs displayed two peaks at 134.4 and 133.4 eV, which correspond to the 2p 1/2 and 2p 3/2 , respectively. 29,54 These XPS results strongly support the successful incorporation of Se, S, and P anions into the TM LDH to form TMCs and TMP architecture.…”

“…It is reported that NC is an excellent negative material due to its large surface area, high electron conductivity, and good electrochemical properties. 4,8 The NC negative electrode exhibited a deviated-rectangular feature within the voltage window of −1.0 to 0.0 V, featuring the electrical double-layer capacitive nature accompanied by a slight pseudocapacitive nature (Figure S17), whereas the Ni− Co−Se NAs delivered noticeable redox peaks within the window regime of −0.2 to 0.75 V, demonstrating its typical battery-like feature. 27 Therefore, the Ni−Co−Se NAs//NC hybrid device could have the potential to deliberately enlarge the working voltage window, thereby improving the energy density (Figure S17c).…”

“…The masses of Ni−Co−P NAs and Ni−Co−S NAs used for the electrochemical studies were ∼1.9 and 2.2 mg, respectively. The ZIF-8 (Zn-based MOF)-derived porous nitrogen-doped carbon (NC) was prepared using a method described by Lee et al 8 The details regarding the material characterization techniques, electrochemical measurements (SC and OER measurements), AEM water electrolyzer single-cell construction, and computational methodology are described in the Supporting Information. The calibration of the Ag/AgCl electrode with respect to the reversible hydrogen electrode (RHE) is shown Figure S1.…”

“…In recent times, research on the advancement of sustainable and eco-friendly energy storage/conversion technologies has attracted considerable attention from the scientific community to surmount the rising energy demands worldwide. − Among the different preeminent energy storage cells, supercapacitors (SCs) have gained extensive interest owing to their intrinsic safety, rapid charging/discharging, high power density, durability, and high efficiency. − However, the relatively lower specific energy of SCs compared to that of conventional secondary batteries has restricted their commercial application. − Assembling asymmetric SCs (ASCs) using battery-like Faradaic positive materials and nanoporous carbon-related negative materials with superior capacity and a large working voltage window could produce an exalted energy density. Apart from energy storage, the production of high-purity and renewable hydrogen fuel using electrochemical water-splitting (EWS) technology (energy conversion device) is considered an indispensable future energy resource. ,− The EWS process includes two core half-cell reactions: hydrogen and oxygen evolution reactions (HER and OER, respectively) at the cathode and anode sides, respectively. , The OER process is more crucial and requires a higher overpotential than the HER because of its four-electron-transfer process associated with sluggish reaction kinetics.…”

Ligand-Controlled Growth of Different Morphological Bimetallic Metal–Organic Frameworks for Enhanced Charge-Storage Performance and Quasi-Solid-State Hybrid Supercapacitors

“…As the mechanism occurs at the electrode, the structure, quality, and nature of the electrode engage in a vital role for better supercapacitor performance . Therefore, different varieties of electrode materials like metal/metal oxides, , layered doubled hydroxides, , MXenes, , metal–organic frameworks (MOFs), − MXene and MOF composites, transition metal dichalcogenide, polymers, composites of transition metal oxides with 3D graphene materials or porous carbon nanofibers, − and composite of metal oxides/sulfides/phosphides/nitrides/selenides − have been recently designed to achieve high-density supercapacitors.…”