Hierarchical Lotus-Seedpod-Derived Porous Activated Carbon Encapsulated with NiCo2S4 for a High-Performance All-Solid-State Asymmetric Supercapacitor

Converting biowaste into carbon-based supercapacitor materials provides a new solution for high-performance and environmentally friendly energy storage applications. Herein, the hierarchical PAC/NiCo2S4 composite structure was fabricated through the combination of activation and sulfuration treatments. The PAC/NiCo2S4 electrode garnered advantages from its hierarchical structure and hollow architecture, resulting in a notable specific capacitance (1217.2 F g-1 at 1.25 A g-1) and superior cycling stability. Moreover, a novel all-solid-state asymmetric supercapacitor (ASC) was successfully constructed, utilizing PAC/NiCo2S4 as the cathode and PAC as the anode. The resultant device exhibited exceptionally high energy (49.7 Wh kg-1) and power density (4785.5 W kg-1), indicating the potential of this biomass-derived, hierarchical PAC/NiCo2S4 composite structure for employment in high-performance supercapacitors.

An Overview of the Emerging Technologies and Composite Materials for Supercapacitors in Energy Storage Applications

Energy storage is one of the challenges currently confronting the energy sector. However, the invention of supercapacitors has transformed the sector. This modern technology's high energy capacity, reliable supply with minimal lag time, and extended lifetime of supercapacitors have piqued the interest of scientists, and several investigations have been conducted to improve their development. However, there is room for improvement. Consequently, this review presents an up-to-date investigation of different supercapacitor technologies' components, operating techniques, potential applications, technical difficulties, benefits, and drawbacks. In addition, it thoroughly highlights the active materials used to produce supercapacitors. The significance of incorporating every component (electrode and electrolyte), their synthesis approach, and their electrochemical characteristics are outlined. The research further examines supercapacitors' potential in the next era of energy technology. Finally, concerns and new research prospects in hybrid supercapacitor-based energy applications that are envisaged to result in the development of ground-breaking devices, are highlighted.

Two-dimensional MXenes: recent emerging applications

MXenes, are a rapidly growing family of two-dimensional materials exhibiting outstanding electronic, optical, mechanical, and thermal properties with versatile transition metal and surface chemistries. A wide range of transition metals and surface termination groups facilitate the properties of MXenes to be easily tuneable. Due to the physically strong and environmentally stable nature of MXenes, they have already had a strong presence in different fields, for instance energy storage, electrocatalysis, water purification, and chemical sensing. Some of the newly discovered applications of MXenes showed very promising results, however, they have not been covered in any review article. Therefore, in this review we comprehensively review the recent advancements of MXenes in various potential fields including energy conversion and storage, wearable flexible electronic devices, chemical detection, and biomedical engineering. We have also presented some of the most exciting prospects by combining MXenes with other materials and forming mixed dimensional high performance heterostructures based novel electronic devices.

Unravelling the redox mechanism and kinetics of a highly active and selective Ni-based material for the oxidative dehydrogenation of ethane

Bridging the gap between catalysis and reaction engineering during the kinetic analysis of the oxidative dehydrogenation of ethane over a highly active and selective Ni-based material.

Advances in Si and SiC Materials for High-Performance Supercapacitors toward Integrated Energy Storage Systems

Silicon (Si), as the second most abundant element on Earth, has been a central platform of modern electronics owing to its low mass density and unique semiconductor properties. From an energy perspective, all-in-one integration of power supply systems onto Si-based functional devices is highly desirable, which inspires significant study on Si-based energy storage. Compared to the well-known Si-anode Li-ion batteries, Si-based supercapacitors possess high power density, long life, and simple working mechanisms, which enables their ease of integration onto a wide range of devices and applications. Besides Si, silicon carbide (SiC), as a physicochemically stable wide-bandgap semiconductor, also attracts research attention as an energy storage material in harsh environments. In this review, a detailed overview of latest advances in materials design, synthesis methods, and performances of Si-based and SiC-based supercapacitors will be provided. Some successful integrated devices, future perspectives, and potential research directions are also highlighted and discussed.

Recent Studies on Supercapacitors with Next-Generation Structures

Supercapacitors have shown great potential as a possible solution to the increasing global demand for next-generation energy storage systems. Charge repositioning is based on physical or chemical mechanisms. There are three types of supercapacitors-the electrochemical double layer, the pseudocapacitor, and a hybrid of both. Each type is further subdivided according to the material used. Herein, a detailed overview of the working mechanism as well as a new method for capacitance enhancement are presented.

Preparation and Analysis of Ni–Co Catalyst Use for Electricity Production and COD Reduction in Microbial Fuel Cells

Microbial fuel cells (MFCs) are devices than can contribute to the development of new technologies using renewable energy sources or waste products for energy production. Moreover, MFCs can realize wastewater pre-treatment, e.g., reduction of the chemical oxygen demand (COD). This research covered preparation and analysis of a catalyst and measurements of changes in the concentration of COD in the MFC with a Ni–Co cathode. Analysis of the catalyst included measurements of the electroless potential of Ni–Co electrodes oxidized for 1–10 h, and the influence of anodic charge on the catalytic activity of the Ni–Co alloy (for four alloys: 15, 25, 50, and 75% concentration of Co). For the Ni–Co alloy containing 15% of Co oxidized for 8 h, after the third anodic charge the best catalytic parameters was obtained. During the MFC operation, it was noted that the COD reduction time (to 90% efficiency) was similar to the reduction time during wastewater aeration. However, the characteristic of the aeration curve was preferred to the curve obtained during the MFC operation. The electricity measurements during the MFC operation showed that power equal to 7.19 mW was obtained (at a current density of 0.47 mA·cm−2).

Kirkendall Growth and Ostwald Ripening Induced Hierarchical Morphology of Ni-Co LDH/MMoS x (M = Co, Ni, and Zn) Heteronanostructures as Advanced Electrode Materials for Asymmetric Solid-State Supercapacitors

By changing the mixed metal sulfide composition, morphology tuning of an active electrode material can be possible, which can have a huge impact on its electrochemical performance. Here, effective morphology tuning of Ni-Co layered double hydroxide (LDH)/MMoS _x (M = Co, Ni, and Zn) heteronanostructures is demonstrated by varying the composition of MMoS _x. Taking advantage of the benefits associated with Kirkendall growth and Ostwald ripening, tunable morphologies were successfully achieved. Among the Ni-Co LDH/MMoS _x (M = Co, Ni, and Zn) heteronanostructures, a Ni-Co LDH/NiMoS _x core-shell structured electrode delivered a high specific capacity of 404 mAh g^-1 at 3 mA cm^-2 and an extraordinary cycling stability (after 10 000 cycles) of 93.2% at 50 mA cm^-2. In addition, an asymmetric supercapacitor (ASC) device coupled with Ni-Co LDH/NiMoS _x as the cathode and Fe₂O₃/reduced graphene oxide as the anode exhibited excellent cell capacity and extraordinary cycling stability. Moreover, the ASC device provided a very high specific energy of 72.6 Wh kg^-1 at a specific power of 522.7 W kg^-1 and maintained the specific power of 23.5 Wh kg^-1 at 5357.6 W kg^-1, demonstrating its high applicability to energy storage devices.

Applications of 2D MXenes in energy conversion and storage systems

This article provides a comprehensive review of MXene materials and their energy-related applications.

Fabrication of a 3D Hierarchical Sandwich Co9 S8 /α-MnS@N-C@MoS2 Nanowire Architectures as Advanced Electrode Material for High Performance Hybrid Supercapacitors

Supercapacitors suffer from lack of energy density and impulse the energy density limit, so a new class of hybrid electrode materials with promising architectures is strongly desirable. Here, the rational design of a 3D hierarchical sandwich Co₉ S₈ /α-MnS@N-C@MoS₂ nanowire architecture is achieved during the hydrothermal sulphurization reaction by the conversion of binary mesoporous metal oxide core to corresponding individual metal sulphides core along with the formation of outer metal sulphide shell at the same time. Benefiting from the 3D hierarchical sandwich architecture, Co₉ S₈ /α-MnS@N-C@MoS₂ electrode exhibits enhanced electrochemical performance with high specific capacity/capacitance of 306 mA h g^-1 /1938 F g^-1 at 1 A g^-1 , and excellent cycling stability with a specific capacity retention of 86.9% after 10 000 cycles at 10 A g^-1 . Moreover, the fabricated asymmetric supercapacitor device using Co₉ S₈ /α-MnS@N-C@MoS₂ as the positive electrode and nitrogen doped graphene as the negative electrode demonstrates high energy density of 64.2 Wh kg^-1 at 729.2 W kg^-1 , and a promising energy density of 23.5 Wh kg^-1 is still attained at a high power density of 11 300 W kg^-1 . The hybrid electrode with 3D hierarchical sandwich architecture promotes enhanced energy density with excellent cyclic stability for energy storage.

Graphene supercapacitor with both high power and energy density

Supercapacitors, based on fast ion transportation, are specialized to provide high power, long stability, and efficient energy storage using highly porous electrode materials. However, their low energy density excludes them from many potential applications that require both high energy density and high power density performances. Using a scalable nanoporous graphene synthesis method involving an annealing process in hydrogen, here we show supercapacitors with highly porous graphene electrodes capable of achieving not only a high power density of 41 kW kg^-1 and a Coulombic efficiency of 97.5%, but also a high energy density of 148.75 Wh kg^-1. A high specific gravimetric and volumetric capacitance (306.03 F g^-1 and 64.27 F cm^-3) are demonstrated. The devices can retain almost 100% capacitance after 7000 charging/discharging cycles at a current density of 8 A g^-1. The superior performance of supercapacitors is attributed to their ideal pore size, pore uniformity, and good ion accessibility of the synthesized graphene.

Recent Breakthroughs in Supercapacitors Boosted by Nitrogen-Rich Porous Carbon Materials

Featured with unique mechanical, electronic and chemical properties, nitrogen-doped carbon materials have become the research hotspot of energy storage. As electrode materials in supercapacitors (SCs), N-doped carbons have demonstrated intriguing flexibility and superb performances in a wide electrochemical window, equipped with versatile properties as both cathodes and anodes for constructing high voltage devices. Compared with limited doping level, N-rich and porous carbon materials (NPCs) are of great desire to release the restricted properties of N species and obtain high specific capacitances (>600 F g^-1), pushing the energy density towards the battery level without scarifying the capacitor-level power ability. In this Research News we firstly discuss the key factors influencing the performance of NPC electrodes to disclose related charge storage mechanisms. In addition, the trade-off among N-content, porous structure and electrical conductivity is involved as well as electrochemical behaviors in different electrolytes. Also, various progressive developments are highlighted systematically ranging from asymmetric to symmetric and hybrid configurations, covering both aqueous and non-aqueous systems. Finally, some stubborn and unsolved problems are summarized, with prospective research guidelines on NPC-based SCs.

Heterostructural MnO2@NiS2/Ni(OH)2 materials for high-performance pseudocapacitor electrodes

Novel heterostructural MnO₂@NiS₂/Ni(OH)₂ nanomaterials are prepared through a seeded hydrothermal method with an enhancement of capacitor performance.

Mesoporous Transition Metal Oxides for Supercapacitors

Recently, transition metal oxides, such as ruthenium oxide (RuO₂), manganese dioxide (MnO₂), nickel oxides (NiO) and cobalt oxide (Co₃O₄), have been widely investigated as electrode materials for pseudo-capacitors. In particular, these metal oxides with mesoporous structures have become very hot nanomaterials in the field of supercapacitors owing to their large specific surface areas and suitable pore size distributions. The high specific capacities of these mesoporous metal oxides are resulted from the effective contacts between electrode materials and electrolytes as well as fast transportation of ions and electrons in the bulk of electrode and at the interface of electrode and electrolyte. During the past decade, many achievements on mesoporous transition metal oxides have been made. In this mini-review, we select several typical nanomaterials, such as RuO₂, MnO₂, NiO, Co₃O₄ and nickel cobaltite (NiCo₂O₄), and briefly summarize the recent research progress of these mesoporous transition metal oxides-based electrodes in the field of supercapacitors.

Influence of particle size on performance of a nickel oxide nanoparticle-based supercapacitor

Particle size effects of Nickel oxide (NiO) as an active material on its supercapacitor performance were investigated.

Preparation of size-selective Mn3O4 hexagonal nanoplates with superior electrochemical properties for pseudocapacitors

Regular Mn₃O₄ hexagonal nanoplates are synthesized for a supercapacitor electrode. This electrode exhibits excellent cycling stability with 100% capacity retention after 5000 cycles.