High-performance Supercapacitors Research Articles

Biomass-Derived Carbon Materials for Advanced Metal-Ion Hybrid Supercapacitors: A Step Towards More Sustainable Energy

Modern research has made the search for high-performance, sustainable, and efficient energy storage technologies a main focus, especially in light of the growing environmental and energy-demanding issues. This review paper focuses on the pivotal role of biomass-derived carbon (BDC) materials in the development of high-performance metal-ion hybrid supercapacitors (MIHSCs), specifically targeting sodium (Na)-, potassium (K)-, aluminium (Al)-, and zinc (Zn)-ion-based systems. Due to their widespread availability, renewable nature, and exceptional physicochemical properties, BDC materials are ideal for supercapacitor electrodes, which perfectly balance environmental sustainability and technological advancement. This paper delves into the synthesis, functionalization, and structural engineering of advanced biomass-based carbon materials, highlighting the strategies to enhance their electrochemical performance. It elaborates on the unique characteristics of these carbons, such as high specific surface area, tuneable porosity, and heteroatom doping, which are pivotal in achieving superior capacitance, energy density, and cycling stability in Na-, K-, Al-, and Zn-ion hybrid supercapacitors. Furthermore, the compatibility of BDCs with metal-ion electrolytes and their role in facilitating ion transport and charge storage mechanisms are critically analysed. Novelty arises from a comprehensive comparison of these carbon materials across metal-ion systems, unveiling the synergistic effects of BDCs’ structural attributes on the performance of each supercapacitor type. This review also casts light on the current challenges, such as scalability, cost-effectiveness, and performance consistency, offering insightful perspectives for future research. This review underscores the transformative potential of BDC materials in MIHSCs and paves the way for next-generation energy storage technologies that are both high-performing and ecologically friendly. It calls for continued innovation and interdisciplinary collaboration to explore these sustainable materials, thereby contributing to advancing green energy technologies.

Organic Solvent Boosts Charge Storage and Charging Dynamics of Conductive MOF Supercapacitors.

Conductive metal-organic frameworks (c-MOFs) and ionic liquids (ILs) have emerged as auspicious combinations for high-performance supercapacitors. However, the nanoconfinement from c-MOFs and high viscosity of ILs slow down the charging process. This hindrance can, however, be resolved by adding solvent. Here, we performed constant-potential molecular simulations to scrutinize the solvent impact on charge storage and charging dynamics of MOF-IL-based supercapacitors. We find conditions for >100% enhancement in capacity and ∼6 times increase in charging speed. These improvements were confirmed by synthesizing near-ideal c-MOFs and developing multiscale models linking molecular simulations to electrochemical measurements. Fundamentally, our findings elucidate that the solvent acts as an "ionophobic agent" to induce a substantial enhancement in charge storage, and as an "ion traffic police" to eliminate convoluted counterion and co-ion motion paths and create two distinct ion transport highways to accelerate charging dynamics. This work paves the way for the optimal design of MOF supercapacitors. This article is protected by copyright. All rights reserved.

Highly conductive titanium nitride core sterically reinforced nickel-vanadium layered double hydroxides for supercapacitors

Nickel vanadium layered double hydroxide (NiV-LDH) is a highly promising electrode material for supercapacitors, but its poor electrochemical durability and conductivity limit its capacitance performance as a high-performance supercapacitor electrode. In contrast, titanium nitride (TiN) stands out for its outstanding electrochemical durability and superior conductivity. In this work, a composite material (TiN@NiV-LDH) with outstanding electrochemical performance was prepared by a simple hydrothermal method, where nickel vanadium layered double hydroxide nanosheets were vertically grown in a staggered manner on the surface of amorphous titanium nitride nanoparticles. The results demonstrate that at a current density of 2 A g−1, the capacitance of TiN@NiV-LDH reaches 712.4 F g−1. In addition, the assembled TiN@NiV-LDH//AC asymmetric supercapacitor exhibits a high energy density of 136.5 Wh kg−1 at a high power density of 1549.9 W kg−1, and after 10,000 cycles at a high current density of 20 A g−1, it retains 80.2 % excellent cyclic stability. This work, based on nickel vanadium layered double hydroxide and utilizing titanium nitride modification, aims to enhance the long-term stability of nickel vanadium layered double hydroxide while preserving its advantageous properties, providing a promising strategy for designing efficient supercapacitor electrodes.

Gas-Phase-Induced Engineering for Fabrication of 3D Hierarchical Porous Nickel and Its Application toward High-Performance Supercapacitors.

Commercial nickel foam (NF), which is composed of numerous interconnected ligaments and hundred-micron pores, is widely acknowledged as a current collector/electrode material for catalysis, sensing, and energy storage applications. However, the commonly used NF often does not work satisfactorily due to its smooth surface and hollow structure of the ligaments. Herein, a gas-phase-induced engineering, two-step gaseous oxidation-reduction (GOR) is presented to directly transform the thin-walled hollow ligament of NF into a three-dimensional (3D) nanoporous prism structure, resulting in the fabrication of a unique hierarchical porous nickel foam (HPNF). This 3D nanoporous architecture is achieved by utilizing the spontaneous reconstruction of nickel atoms during volume expansion and contraction in the GOR process. The process avoids the involution of acid-base corrosion and sacrificial components, which are facile, environmentally friendly, and suitable for large-scale fabrication. Furthermore, MnO2 is electrochemically deposited on the HPNF to form a supercapacitor electrode (HPNF/MnO2). Because of the fully open structure for ion transport, superhydrophilic properties, and the increased contact area between MnO2 and the current collector, the HPNF/MnO2 electrode exhibits a high specific capacitance of 997.5 F g-1 at 3 A g-1 and remarkable cycling stability with 99.6% capacitance retention after 20000 cycles in 0.1 M Na2SO4 electrolyte, outperforming most MnO2-based supercapacitor electrodes.

Multiple phase transformation of ZIF-L to LDH and Ag nanoparticles decorated on CoNi layered double hydroxides for high-performance supercapacitor and highly efficient hydrogen evolution reaction

ZIF-L-derived binary layered double hydroxide (LDH) established active catalysts have been shown to have potential as electrode materials in the development of high-performance supercapacitors (SCs) and hydrogen evaluation reactions (HER). This study uses conductive nano-silver (Ag) particles in hierarchically integrated CoNi-LDH nanosheets (NSs), which are described. The developed Ag@CoNi-LDH NSs electrode has a very high specific capacitance of 2878 F g−1 at 0.5 A g−1 and an impressive rate capability. This is due to consistent morphology, plentiful electroactive sites, homogeneous particle size, and decreased electronic/ionic impedance. The fabrication of solid-state hybrid supercapacitors (HSCs) using Ag@CoNi-LDH NSs as the positive electrode and activated carbon (AC) as the negative electrode in PVA/KOH polymer gel electrolytes has been described. The prepared supercapacitors achieve a maximum energy density of 105 Wh kg−1 at power densities of 1183 Wh kg−1, coupled with excellent initial capacitance retentions of 97 % after 20,000 cycles. Ag@CoNi-LDH NSs demonstrate effective electrocatalytic activity towards HER with an ultra-low overpotential of 26 mV at 10 mA cm−2 and the associated Tafel value of 35 mV dec−1 using 0.5 M acidic electrolyte. It is possible to attribute the extraordinary electrochemical performance to the thoughtful mixture of two electroactive materials in the future.

Star-shaped PEDOT:PSS conductive polymers with reduced graphene oxide for high performance supercapacitor

Star-shaped PEDOT:PSS conductive polymers with reduced graphene oxide for high performance supercapacitor

A Three-Dimensional Points–Lines–Planes Interweaved Conductive Additive with Ultrahigh Electron Transfer for High-Performance Supercapacitors

A Three-Dimensional Points–Lines–Planes Interweaved Conductive Additive with Ultrahigh Electron Transfer for High-Performance Supercapacitors

Coal tar-pitch derived porous carbons with zinc oxide nanoparticles as a dual-functional template and activating agent for high-performance supercapacitors

Coal tar-pitch derived porous carbons with zinc oxide nanoparticles as a dual-functional template and activating agent for high-performance supercapacitors

Rational design of hierarchical porous reduced graphene oxide/9,10-phenanthraquinone/porous carbon nanocomposites for high-performance supercapacitors

The development of advanced electrode material is crucial for promoting the application of new high-performance green energy storage devices and remains a great challenge. Herein, by introducing porous carbon (PC) or carbon nanotubes (CNTs) to further modify the redox-active 9,10-phenanthrenequinone (PQ) molecule non-covalently functionalized reduced graphene oxide (RGO), we have designed and synthesized RGO/PQ/PCs (RPPs) and RGO/PQ/CNTs-10 (RPC-10) nanocomposites using a simple one-step solvothermal method. Benefiting from the optimization of the hierarchical porous nanostructures and each composition further strengthens their respective advantages in the novel synthesized nanocomposites (RPPs and RPC-10), the RPPs and RPC-10 electrodes demonstrated significantly superior electrochemical energy storage performance over the RGO and RGO/PQ (RP) electrodes, especially for the RPP-10 electrode with a high specific capacitance of 343.5 F g−1 at 0.5 A g−1 and good rate capability (69.23 %, 0.5 − 40 A g−1). Furthermore, both the symmetric supercapacitor assembled with the optimal RPP-10 electrode and the hybrid supercapacitor assembled with the RPP-10 negative electrode and the NCSRC-24 positive electrode previously reported show excellent energy densities and ultra-long cycling stabilities. This result demonstrates that the synthesized novel RPP-10 nanocomposite is a highly promising candidate for new light-weight, sustainable, high-flexible and high-performance energy storage devices.

The Mass-Balancing between Positive and Negative Electrodes for Optimizing Energy Density of Supercapacitors.

Supercapacitors (SCs) are some of the most promising energy storage devices, but their low energy density is one main weakness. Over the decades, superior electrode materials and suitable electrolytes have been widely developed to enhance the energy storage ability of SCs. Particularly, constructing asymmetric supercapacitors (ASCs) can extend their electrochemical stable voltage windows (ESVWs) and thus achieve high energy density. However, only full utilization of the electrochemical stable potential windows (ESPWs) of both positive and negative electrodes can endow the ASC devices with a maximum ESVW by using a suitable mass-ratio between two electrodes (the mass-balancing). Nevertheless, insufficient attention is directed to mass-balancing, and even numerous misunderstandings and misuses have appeared. Therefore, in this Perspective, we focus on the mass-balancing: summarize theoretic basis of the mass-balancing, derive relevant relation equations, analyze and discuss the change trends of the specific capacitance and energy density of ASCs with mass-ratios, and finally recommend some guidelines for the normative implementation of the mass-balancing. Especially, the issues related to pseudocapacitive materials, hybrid devices, and different open circuit potentials (OCPs) of the positive and negative electrodes in the mass-balancing are included and emphasized. These analyses and guidelines can be conducive to understanding and performing mass-balancing for developing high-performance SCs.

The Optimal Doping Ratio of Fe2O3 for Enhancing the Electrochemical Stability of Zeolitic Imidazolate Framework-8 for Energy Storage Devices

This paper aims to discover a novel composite material that has great potential for manufacturing high-performance supercapacitors suitable for diverse applications, such as electric vehicles, portable electronics, and stationary energy storage systems. Zeolitic imidazolate framework-8 (ZIF-8) doped by different concentrations up to 5 wt.% of nanosized Fe2O3 have been prepared (ZIF-8/Fe2O3). The effect of doping ratio 1, 3, and 5 wt.% on the structural and electrochemical properties of ZIF-8/Fe2O3 has been investigated. The structural characterization has been carried out using TGA, BET, XRD, and FTIR. The XRD analysis revealed that the crystalline size of our sample increased by approximately 16% as a result of doping ZIF-8 with 5 wt.% of Fe2O3. The structural analysis of the doped samples revealed that the material exhibited enhanced thermal stability and porosity, with an increase of approximately 105 m2/g. The introduction of doped nanometal oxides improved the capacitance value of ZIF-8 by significantly increasing its surface area. Additionally, the electron transport efficiency within ZIF-8/5 wt.% Fe2O3/electrode is increased. The Nyquist plot decreases as the doping of Fe2O3 increases. This indicates a decrease in the charge transfer resistance at the electrode–electrolyte interface, which is desired in applications such as batteries, fuel cells, or electrochemical sensors where faster electron transfer is needed for improved performance.

Morphology evolution of bacterial cellulose carbon and loaded with MnO2 microspheres for high performance supercapacitors

The rapid development of economy and technology caused numerous irreversible effects on the environment, and the rational use and storage of existing resources have became an indispensable process in modern development. Energy storage through supercapacitors can effectively alleviate part of the energy crisis. Here, the effects of heating rates on the morphology of carbonized bacterial cellulose (CBC) carbon and its electrochemical properties were studied and CBC-5 (heating rate of 5 ℃/min) with porous structure was confirmed to be supporting material for loading MnO2. The specific capacitance of CBC-5@MnO2 composites was high up to 190 F g−1 at 1 A g−1, and its capacitance retention rate was up to 96.6% after 8000 cycles. The superior electrochemical performance cannot be achieved without the cooperative effect among the metal oxides and carbon materials, which also benefits from the fast transport of ions and electrons in solution. The assembled CBC-5//CBC-5@MnO2-6 h hybrid supercapacitors exhibited largest energy density and power density values of 44.5 Wh kg−1 (at 0.2 A g−1) and 11111.1 W kg−1 (at 10 A g−1), respectively. The assembled button cells can light up small LED bulbs for at least 10 min. The porous bacterial cellulose carbon can provided possibilities for high electrode design.

Iodine intercalation-assisted alkali activation constructs coal-based porous carbon for high-performance supercapacitors

Supercapacitors have the advantages of fast charging and discharging speeds, high power density, long cycle life, and wide operating temperature range. They are widely used in portable electronic equipment, rail transit, industry, military, aerospace, and other fields. The design and preparation of low-cost, high-performance electrode materials still pose a bottleneck that hinders the development of supercapacitors. In this paper, coal was used as the raw material, and the coal-based porous carbon electrode material was constructed using the iodine intercalation-assisted activation method and used for supercapacitors. The CK-700 electrode exhibits excellent charge storage performance in a 6 M potassium hydroxide (KOH) electrolyte, with a maximum specific capacitance of 350 F/g at a current density of 0.5 A/g. In addition, it has an excellent rate performance (310 F/g at 1 A/g) and cycle stability (capacitance retention up to 91.7 % after 30000 cycles). This work provides a method for realizing high-quality, high-yield and low-cost preparation of coal-based porous carbon, and an idea for improving the performance of supercapacitors.

ZnMnCo-S nanoneedle arrays as battery-type eletrodes for high-performance hybrid supercapacitors

Transition metal sulfides are used in the field of supercapacitors due to their remarkable electrical conductivity and superior energy density. However, few research has been conducted on how the sulfidation process affects the structure and electrochemical properties of electrodes. The nanoneedle array Zn-Mn-Co sulfide (ZMC-S/NF) electrode is prepared by directly growing on nickel foam (NF) via a two-step hydrothermal technique. During the first step, the Zn-Mn-Co carbonate hydroxide nanoneedle skeleton can be obtained. During the second step, the nanoneedle skeletons are etched, and rough nanoneedle arrays are created by the introduced sulfur ions,i.e., the sulfidation process. The ZMC-S/NF electrode exhibits a specific capacity of 1401.0 C g−1 at 2 A g−1. It still has excellent rate performance with a specific capacity of 1015.3 C g−1 at 20 A g−1. Moreover, it exhibits excellent cycling stability with 81.9% capacity retention after 10,000 cycles. ZMC-S/NF as the cathode and activated carbon (AC) as the anode are assembled to be a hybrid supercapacitor (HSC), which has an energy density of 43.4 Wh kg−1 at a power density of 700.4 W kg−1. The effect of adding Zn and Mn to the Co3S4 on energy band structure and density of states during the sulfidation process is calculated by the DFT. The HSC devices constructed by two series-connected ZMC-S/NF//AC can light a star made by ten 1.8 V-red Light Emitting Diodes (LEDs) for 10 minutes.

Designing strategically functionalized conjugated microporous polymers with pyrene and perylenetetracarboxylic dianhydride moieties with single-walled carbon nanotubes to enhance supercapacitive energy storage efficiency

We utilize straightforward and traditional Sonogashira coupling reactions to synthesize two conjugated microporous polymers linked with pyrene (referred to as PyT-PTCDA and PyT-PHTD CMPs) by combining the common precursor of 1,3,6,8-tetraethynylpyrene (PyT) with 1,7-dibromo-3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA-Br2) and 3,6-dibromophenanthrene-9,10-dione (PHTD-Br2). Various analytical techniques, including spectroscopy and microscopy, are employed to characterize these two PyT-CMP materials. The PyT-PTCDA CMP exhibits notable thermal stability (with a decomposition temperature of 351 °C and a char yield of 61 wt %). We combine the PyT-PTCDA and PyT-PHTD CMPs with exceptionally conducting single-walled carbon nanotubes (SWCNTs) through π-π stacking interactions between SWCNTs and PyT unit to improve their electrical conductivity and electrochemical performance. Electrochemical evaluations reveal that the PyT-PTCDA CMP/SWCNTs nanocomposite shows an impressive capacitance of 376 F g−1 (at 0.5 A g−1) in a three-electrode system. After undergoing 5000 cycles of charging and discharging, it maintained 98 % of its original capacitance while demonstrating an energy density of 52 Wh/kg. Additionally, in a symmetric coin cell system, the energy density is 17 Wh/kg and the capacitance is 119 F g−1 for PyT-PTCDA CMP/SWCNTs. This approach presents a promising avenue for developing high-performance supercapacitors by strategically blending PyT-CMPs with highly conductive SWCNTs.

Cellulose-based aerogel derived N, B-co-doped porous biochar for high-performance CO2 capture and supercapacitor

The remarkable characteristics of porous biochar have generated significant interest in various fields, such as CO2 capture and supercapacitors. The modification of aerogel-derived porous biochar through activation and heteroatomic doping can effectively enhance CO2 adsorption and improve supercapacitor performance. In this study, a novel N, B-co-doped porous biochar (NBCPB) was synthesized by carbonating and activating the N, B dual-doped cellulose aerogel. N and B atoms were doped in-situ using a modified alkali-urea method. The potassium citrate was served as both an activator and a salt template to facilitate the formation of a well-developed nanostructure. The optimized NBCPB-650-1 (where 650 corresponded to activation temperature and 1 represented mass ratio of potassium citrate activator to carbonized NBCPB-400 precursor) displayed the largest micropore volume of 0.40 cm3·g−1 and a high specific surface area of 891 m2·g−1, which contributed to an excellent CO2 adsorption capacity of 4.19 mmol·g−1 at 100 kPa and 25 °C, a high CO2/N2 selectivity, and exceptional reusability (retained >97.5 % after 10 adsorption-desorption cycles). Additionally, the NBCPB-650-1 electrode also delivered a high capacitance of 220.9 F·g−1 at 1 A·g−1. Notably, the symmetrical NBCPB-650-1 supercapacitor exhibited a high energy density of 9 Wh·kg−1 at the power density of 100 W·kg−1. This study not only presents the potential application of NBCPB-650-1 material in CO2 capture and electrochemical energy storage, but also offers a new insight into easy-to-scale production of heteroatomic-modified porous biochar.

Preparation of Positive and Negative Composite Electrode Materials for High-Performance Aqueous Asymmetric Supercapacitor by a Sequential Two-Step Reaction

Preparation of Positive and Negative Composite Electrode Materials for High-Performance Aqueous Asymmetric Supercapacitor by a Sequential Two-Step Reaction

Time-dependent synthesis of tungsten disulfide for flexible supercapacitors

Tungsten disulfide (WS2) with various nanostructures was synthesized for times ranging from 6 to 72 h, using a simple and easy hydrothermal technique, for high-performance supercapacitor applications. The synthesized WS2 for 24 h (WS2–24), among other synthesized WS2, exhibited flower-like structures, composed of numerous nanosheets, demonstrating superior electrochemical properties in terms of electrochemical surface area, charge transfer resistance, specific capacitance, and rate capability. In addition, WS2–24 was coated on a flexible activated carbon cloth substrate to make flexible electrodes and assemble a flexible symmetric supercapacitor with a gel electrolyte. The flexible supercapacitor exhibited a specific capacitance of 262.5 F g−1 at 1 A g−1 with an energy density of 23.6 Wh kg−1 and a power density of 802 W kg−1. It also showed excellent capacitance retention of 94.5 % and a Coulombic efficiency of 86.4 % after 5000 cycles. The remarkable electrochemical properties of the synthesized WS2 materials highlight them as highly effective active materials for high-performance supercapacitor electrodes.

Boosting the electrochemical properties of MoO3/MnFe2O4/MXene for high-performance supercapacitor applications

The expanding population and extensive usage of energy-consuming sources are the main factors driving the interest of current researchers toward the development of extremely effective and useful electrode materials for high-power energy storage devices. A novel class of 2D transition metal carbides such as MXene has captured significant attention and has distinguished itself from other electrode materials because of its remarkable electrochemical characteristics. In this work, we have fabricated MoO3 and MnFe2O4 via a simple co-precipitation method. Further, we design multifunctional MoO3/MnFe2O4/MXene composite by the combination of MoO3/MnFe2O4 and MXene through the sonication route. SEM results confirmed the fabrication of nanorods of MoO3 and nanoparticles of MnFe2O4, sandwiched within the MXene sheets. As evident from CV profiles, at 10 mVs−1 MoO3/MnFe2O4@MXene showed a higher specific capacitance of 817 Fg−1 than other electrode materials mainly because of the combined effect of MoO3/MnFe2O4 and the conductive nature of MXene sheets. Furthermore, even after 10,000 cycles, MoO3/MnFe2O4/MXene demonstrated outstanding cyclic stability, maintaining 90.2 % retention of its initial specific capacitance. Furthermore, MoO3/MnFe2O4/MXene showed less solution resistance and charge transfer resistance than all other prepared materials. These findings suggest that the MoO3/MnFe2O4/MXene composite is a competent capacitive material in the supercapacitor research area.

High Volumetric Energy Density Supercapacitor of Additive-Free Quantum Dot Hierarchical Nanopore Structure.

The high surface-area-to-volume ratio of colloidal quantum dots (QDs) positions them as promising materials for high-performance supercapacitor electrodes. However, the challenge lies in achieving a highly accessible surface area, while maintaining good electrical conductivity. An efficient supercapacitor demands a dense yet highly porous structure that facilitates efficient ion-surface interactions and supports fast charge mobility. Here we demonstrate the successful development of additive-free ultrahigh energy density electric double-layer capacitors based on quantum dot hierarchical nanopore (QDHN) structures. Lead sulfide QDs are assembled into QDHN structures that strike a balance between electrical conductivity and efficient ion diffusion by employing meticulous control over inter-QD distances without any additives. Using ionic liquid as the electrolyte, the high-voltage ultrathin-film microsupercapacitors achieve a remarkable combination of volumetric energy density (95.6 mWh cm-3) and power density (13.5 W cm-3). This achievement is attributed to the intrinsic capability of QDHN structures to accumulate charge carriers efficiently. These findings introduce innovative concepts for leveraging colloidal nanomaterials in the advancement of high-performance energy storage devices.