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Highlights Manganese oxides have emerged as promising electrode materials for supercapacitors. Despite extensive efforts to improve their conductivity and structural stability through various manganese oxide/conductor nanocomposites, achieving efficient and reliable energy storage electrode materials has remained challenging. In this study, we propose a meticulous “dual enhancement” strategy, where three‐dimensional (3D) nanostructured polyaniline/manganese oxide composites (PM) are synthesized via an in situ method and further integrated with graphene wrapping to form polyaniline/manganese oxide/graphene nanocomposites (PMG). Electrochemical characterization reveals that PMG exhibits a remarkable specific capacitance of up to 403 F g−1 (at 1 A g−1), with a favorable capacitance retention of 80.2% after 5000 cycles, along with a wide potential window. This enhancement is attributed to the synergistic effects of polyaniline, which provides a supportive framework and electron transport pathways, and graphene, which offers external protection and enhances conductivity pathways. Assembled symmetrical supercapacitors demonstrate outstanding energy density (32.7–23.3 Wh kg−1) and power density (720–4500 W kg−1) at a high operating voltage of 1.8 V, surpassing the performance of many reported high‐performance supercapacitors. This study provides valuable insights for advancing manganese oxide electrode materials and is expected to catalyze their widespread adoption in energy storage applications. “Dual enhancement” is implemented by PANI supporting and rGO wrapping. The conductivity and structural stability of composite electrode is greatly enhanced. Improved capacitance (403 F g−1, 1 A g−1) and cycling stability (80.2%) is achieved. The symmetrical supercapacitor has high voltage and energy density (32.7 Wh kg−1). [ABSTRACT FROM AUTHOR]

Layered double hydroxides (LDHs) represent a category of two-dimensional layered intercalation materials, showing significant potential as electrode materials for the production of high-energy-density supercapacitors due to their tunable composition, ease of synthetic modification, and low cost. Here, we constructed alkali-etched NiAl LDH-OH nanosheets/Ag nanoparticles (NPs) composite material (Ag@NiAl LDH-OH) for high-performance supercapacitors through a simple solvent-thermal reaction. The alkali treatment is employed to selectively etch some Al3+ ions, generating cation vacancies as active sites for energy storage. Additionally, under the simultaneous influence of strong alkalis and vacancies, the interlayer spacing of LDHs expands, aiding in the promotion of interlayer ion mobility. Meanwhile, the decoration of silver nanoparticles ensures excellent electron conductivity in the NiAl-LDH-OH nanosheets, thereby facilitating improved utilization of the active substance and achieving outstanding rate performance. The Ag@NiAl LDH-OH electrode, when prepared, demonstrates a significant increase in specific capacitance, reaching 1790 F g−1 at a current density of 1 A g−1. This represents approximately 7 times the specific capacitance of the pristine NiAl LDH electrode, with a capacity retention of 79 % even under a high current density of 20 A g−1. Moreover, the assembled asymmetric supercapacitor (ASC) attains a maximum energy density of 138.25 Wh kg−1 at a power density of 700 W kg−1, maintaining 81 % of its initial specific capacitance after 20000 cycles. This research introduces novel pathways for advancing high-energy-density SCs. [ABSTRACT FROM AUTHOR]

Polythiophene (PTh) was modified with tin oxide (SnO2) and tin sulphide (SnS2) nanoparticles to enhance its electrochemical performance. The resulting PTh/SnO2/SnS2 material was characterized to understand its surface influence, crystalline structure, and electrochemical behavior, and the results were compared with those of pristine PTh. The study revealed that surface modification improved the structural stability of PTh while maintaining its specific capacitance. Electrochemical properties were assessed using cyclic voltammetry (CV) and AC impedance techniques in a 3 M KOH electrolyte, yielding specific capacitances of 226 F g− 1 for PTh, 571 F g− 1 for PTh/SnO2, 625 F g− 1 for PTh/SnS2, and 946 F g− 1 for PTh/SnO2/SnS2 at 5 A g− 1. This enhancement was attributed to the synergistic effect of the Sn4+ ions in the PTh/SnO2/SnS2 electrode material. In the KOH electrolyte, the PTh/SnO2/SnS2 electrode demonstrated an average specific energy and specific power density of 681 Wh kg− 1 and 5273 W kg− 1, respectively. Remarkably, only 7% of the initial capacitance was lost after 10,000 cycles. The resulting PTh/SnO2/SnS2 nanocomposite exhibited stable and porous layered structures, indicating its potential for supercapacitor applications. The integration of SnO2 and SnS2 nanoparticles enhances the structural stability of polythiophene films. This improved stability ensures that the films can maintain their integrity and functionality over multiple charge-discharge cycles, leading to a longer lifespan in supercapacitor devices. This study demonstrated that PTh/SnO2/SnS2 nanomaterials offer good structural stability and electrochemical performance, making them promising materials for supercapacitors. [ABSTRACT FROM AUTHOR]

MXenes are a kind of novel and interesting new materials, and carbon dots (CDs) are also concerned because of their processability, versatility, environmental protection, and low cost. Both MXenes and CDs are chemically stable and have a large surface area and high electrical conductivity, which are promising alternative electrode materials for supercapacitors. Moreover, MnO2 can also improve the energy density of the electrode materials. In this paper, Ti3C2Tx/CDs and Ti3C2Tx/CDs@MnO2 were prepared by a hydrothermal method and their supercapacitor performance were also investigated by a series of electrochemical methods. From the CV profile in a three-electrode system, Ti3C2Tx/CDs@MnO2 electrode exhibited a high specific capacitance of 281.3 F g−1 at a scan rate of 5 mV s−1, which was higher than that of Ti3C2Tx/CDs (160.3 F g−1). Ti3C2Tx/CDs showed a good cycling stability with a capacitance retention of 82.38% after 10,000 cycles. Meanwhile, a symmetric supercapacitor was successfully assembled using Ti3C2Tx/CDs@MnO2 as electrodes, with an energy density of 5.77 Wh kg−1 at a corresponding power density of 120 W kg−1. This work offers a theoretical foundation and a technological path for synthesizing highly effective ternary composite of MXene-based as energy storage materials. [ABSTRACT FROM AUTHOR]

As a typical spinel structure material, ZnMn2O4 has been widely researched in the field of electrode materials. However, ZnMn2O4 nanoparticles as electrode materials for supercapacitors have the disadvantages of low conductivity, inferior structural integrity, and easy aggregation, resulting in unsatisfying electrochemical performance. In this work, we use a hydrothermal method and high-temperature calcination to deposit ZnMn2O4 nanoparticles on carbon cloth and explore the influence of hydrothermal reaction time on the deposition morphology and distribution of ZnMn2O4 nanoparticles on carbon cloth. The deposition process of ZnMn2O4 nanoparticles on carbon cloth was analyzed, and a ZMO-9 electrode was deduced to be the most suitable electrode for supercapacitors. A series of electrochemical performance tests show that the ZMO-9 electrode has excellent specific capacitance (specific capacity) (499 F·g−1 (299.4 C·g−1) at a current density of 1 A·g−1) and rate performance (75% capacitance retention at a current density of 12 A·g−1). The assembled asymmetric supercapacitor has an energy density of 46.6 Wh·kg−1 when the power density is 800.1 W·kg−1. This work provides a reference for the structural design of ZnMn2O4 supercapacitor electrode materials and the improvement of electrochemical properties. [ABSTRACT FROM AUTHOR]

Supercapacitors have emerged as promising electrochemical storage, offering advantages such as rapid charge/discharge rates and environmental friendliness. Nevertheless, their practical applications have been limited due to their lower energy density, and selecting electrode materials with superior energy storage properties remains a critical factor. NiCo2S4 nanomaterials have gained significant attention due to their high theoretical specific capacitance, narrow band gap, and abundant redox reaction active sites, but challenges such as poor cyclic stability and volumetric effects associated with prolonged charging and discharging persist. This paper reviews the recent research progress on NiCo2S4 nanomaterials and comprehensively discusses various strategies to improve the electrochemical performance of NiCo2S4, including morphology control, design and development of NiCo2S4-based composite electrode nanomaterials, doping of different elements, utilization of defect engineering and phase engineering strategies, and exploration of theoretical studies. Finally, the prospects and challenges for the development of NiCo2S4 electrode nanomaterials in the field of supercapacitors are also suggested. [ABSTRACT FROM AUTHOR]

Transition bimetallic sulfides show significant promise for energy‐related applications because of their plentiful active sites and synergistic redox activity. However, limited pore size and low‐conductivity issues hinder their application. The structure of NiCo–S with rich sulfur vacancies is first predicted by density functional theory (DFT) calculations. Different sulfur vacancy concentrations are modeled by DFT calculations, and the results confirm that sulfur vacancies enhance the conductivity of the electrode material and are more beneficial for the adsorption of OH* species. It is verified by the differential charge density that the electric field formed on the surface of the electrode can lead to strong interfacial interactions by electron aggregation, which promotes electron/ion transfer kinetics. Furthermore, NiCo–S nanosheets are prepared on carbon cloth enriched with different concentrations of sulfur vacancies (denoted as NiCo‐Sv‐x, with x representing the concentration of sulfur vacancies) by sulfide etching NiCo‐MOF and annealing under H2/Ar atmosphere. The NiCo‐Sv‐x electrodes obtained are applied to the cathode of supercapacitors and the anode of the oxygen evolution reaction. Through combining experimental and theoretical analysis, the effect of vacancy defect engineering on the electrochemical performance of the electrode materials is further confirmed. [ABSTRACT FROM AUTHOR]

Manganese dioxide (MnO2) nanoparticles were modified by graphitic carbon nitride (GCN) and polylpyrrole (Ppy) to enhance their electrochemical performance. The surface influence, crystalline structure, and electrochemical performance of the Ppy/GCN/MnO2 material were characterized and compared with those of pristine MnO2. It is found that surface modification can improve the structural stability of MnO2 without decreasing its available specific capacitance. The electrochemical properties of synthesized Ppy/GCN/MnO2 electrode were evaluated using cyclic voltammetry (CV) and AC impedance techniques in 5 M KOH electrolyte. Specific capacitances of 486, 815, 921, and 1377 F/g were obtained for MnO2, Ppy/MnO2, GCN/MnO2, and Ppy/GCN/MnO2, respectively, at 5 A/g. This improvement is attributed to the synergistic effect of GCN and Ppy in the Ppy/GCN/MnO2 electrode material. The Ppy/GCN/MnO2 electrode in KOH has average specific energy and specific power densities of 172 Wh kg−1 and 2065 W kg−1, respectively. Only 2 % of the capacitance's initial value is lost after 10,000 cycles. The resulting Ppy/GCN/MnO2 nanocomposite had very stable and porous layered structures. This work demonstrates that Ppy/GCN/MnO2 nanomaterials exhibit good structural stability and electrochemical performance and are good materials for supercapacitor applications. [ABSTRACT FROM AUTHOR]

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Poly (3-methylthiophene) (P3MT) was modified by tin disulfide (SnS2) and zirconium disulfide (ZrS2) nanoparticles to enhance its electrochemical performance. The surface influence, crystalline structure, and electrochemical performance of the P3MT/SnS2/ZrS2 material were characterized and compared with that of pristine P3MT. It is found that surface modification can improve the structural stability of P3MT without decreasing its available specific capacitance. The electrochemical properties of synthesized P3MT/SnS2/ZrS2 electrode were evaluated using cyclic voltammetry (CV) and AC impedance techniques in 6 M KOH electrolyte. Specific capacitances of 278, 697, 759, and 1396 F/g were obtained P3MT, P3MT/SnS2, P3MT/ZrS2, and P3MT/SnS2/ZrS2, respectively, at 1 A/g. This improvement is attributed to the synergistic effect of SnS2 and ZrS2 in the P3MT/SnS2/ZrS2 electrode material. The P3MT/SnS2/ZrS2 electrode in KOH has average specific energy and specific power densities of 951 Wh kg−1 and 5457 W kg−1, respectively. Only 5% of the capacitance's initial value is lost after 10,000 cycles. The resulting P3MT/SnS2/ZrS2 nanocomposite had very stable and porous layered structures. This work demonstrates that P3MT/SnS2/ZrS2 nanomaterials exhibit good structural stability and electrochemical performance and are good materials for supercapacitor applications. [ABSTRACT FROM AUTHOR]

The creation of effective supercapacitor materials is still a priority in the quest to improve energy storage technology. Herein, we present a novel nanocomposite composed of carbon nanoparticles (CNPs) and colloidal SnO2 quantum dots (c-SQDs) or colloidal SnO2 ultrasmall nanoparticles, synthesized through a facile sonochemical-assisted hydrothermal approach. The XRD and XPS analyses confirmed the successful synthesis and composition of the CNP/c-SQD nanocomposite. Morphology studies revealed a well-dispersed morphology with intimate interfacial interactions between the CNPs and c-SQDs. Specifically, the nanocomposite exhibited a high specific capacitance of 569 F/g at a current density of 1 A/g, surpassing conventional carbon-based supercapacitors. Furthermore, the nanocomposite displayed excellent stability with 99% capacity retention after 5000 cycles, indicative of its superior cyclability. These results underscore the potential of the CNP/c-SQD nanocomposite as a promising electrode material for high-performance supercapacitor applications, offering enhanced charge storage capacity, stability, and cyclability. This study contributes to the advancement of energy storage technologies, paving the way for the development of efficient and sustainable electrochemical energy storage devices. [ABSTRACT FROM AUTHOR]

Poly (3‐methylthiophene) (P3MT) was modified by nickel oxide (NiO) and nickel sulfide (NiS) nanoparticles to enhance its electrochemical performance. The surface influence, crystalline structure, and electrochemical performance of the P3MT/NiO/NiS material were characterized and compared with that of pristine P3MT. It is found that surface modification can improve the structural stability of P3MT without decreasing its available specific capacitance. The electrochemical properties of synthesized P3MT/NiO/NiS electrode were evaluated using cyclic voltammetry and alternating current impedance techniques in 3 M KOH electrolyte. Specific capacitances of 253, 764, 932, and 1434 F g−1 were obtained for P3MT, P3MT/NiO, P3MT/NiS, and P3MT/NiO/NiS, respectively at 5 A g−1. This improvement is attributed to the synergistic effect of Ni2+ ions in the P3MT/NiO/NiS electrode material. The P3MT/NiO/NiS electrode in KOH has average specific energy and specific power densities of 1032 Wh kg−1 and 6192 W/kg, respectively. Only 2% of the capacitance's initial value is lost after 10,000 cycles. The resulting P3MT/NiO/NiS nanocomposite had very stable and porous layered structures. This work demonstrates that P3MT/NiO/NiS nanomaterials exhibit good structural stability and electrochemical performance, and are good material for supercapacitor applications. Highlights: The P3MT/NiO/NiS nanocomposite is fabricated and characterized as supercapacitor electrode.The incorporation of NiO/NiS in the poly (3‐methylthiophene) has improved the electrochemical performance.The P3MT/NiO/NiS electrodes retained 98% of their specific capacitance after 10,000 cycles.The P3MT/NiO/NiS nanocomposite electrode showed specific capacitance of 1434 F g−1 at 5 A g−1.The stability of the nanocomposite was enhanced without altering its morphology and chemical structure. [ABSTRACT FROM AUTHOR]

Developing new electrode materials with good temperature‐dependent electrochemical performance has become a great issue for the deployment of hybrid supercapacitors with wide temperature tolerance. In this work, a series of Ta‐substituted SrCo1‐xTaxO3‐δ (x=0.05, 0.10, 0.15, 0.20) perovskites have been studied as positive electrodes for hybrid supercapacitors in terms of their structures, elemental valence states and electrochemical performances. Incorporating Ta into SrCoO3‐δ perovskite not only stabilizes the crystallite structure but also notably improves electrochemical activities. The SrCo0.95Ta0.05O3‐δ@CC delivers the highest specific capacity (Qsp) of 227.91 C g−1 at 1 A g−1, which is attributed to the highest oxygen vacancy content and the fastest oxygen diffusion kinetics. The hybrid supercapacitor SrCo0.95Ta0.05O3‐δ@CC//AC@CC exhibits a high energy density of 22.82 Wh kg−1@775.09 W kg−1 and a stable long‐term cycle life (5000 cycles) with 90.7 % capacity retention. As temperature increases from 25 to 85 °C, the capacitance properties are improved at elevated temperatures for both electrode and device due to the increased electrolyte conductivity. The outstanding electrochemical results present that SrCo1‐xTaxO3‐δ perovskite holds good prospects for hybrid supercapacitors with wide temperature tolerance. [ABSTRACT FROM AUTHOR]

The limited electrical conductivity of manganese dioxide (MnO2) hinders its broad use as an electrode in all-solid-state supercapacitor devices (ASDs). To overcome this, trivalent gadolinium (Gd) and erbium (Er) ions are incorporated into MnO2, effectively addressing the issue. This involves synthesizing α-MnO2 nanorods infused with Gd and Er by using a modified chemical process. Through the creation of crystal defects, augmentation of electrical conductivity, and increased porosity, the electrochemical performance is significantly enhanced. Cyclic voltammetry and galvanostatic charge–discharge measurements within the range of −0.2 to +0.6 V unveil improved capacitance values of 798 and 647 F g−1 at 1 A g−1 current density for Gd- and Er-doped α-MnO2 respectively, maintaining 92.4% and 89.7% charge retention after 5000 cycles. Analysis reveals that both samples are primarily dominated by electric double-layer capacitance (EDLC). Furthermore, surface capacitance outweighs diffusion-controlled processes in the electrochemical storage mechanism. The Gd-doped α-MnO2 coated device depicts a peak energy density of 78.5 Wh kg–1 at 106.01 W kg–1 power density for 0.5 A g−1 and maximum power density of 498.1 W kg–1 at 9.13 Wh kg–1 energy density for 3 A g−1. Even a handcrafted 1 cm × 1 cm device achieves 2.252 V potential, effectively illuminating commercial LEDs. [ABSTRACT FROM AUTHOR]

Biomass-derived carbon materials have attracted more and more attention as efficient and cheap super--capacitor electrode materials due to their renewability and flexible microstructure tunability. However, the original biomass-derived carbon has the disadvantages of low porosity, low specific surface area and insufficient specific capacitance. The specific surface area, pore structure and conductivity of electrode materials will affect the energy storage performance of supercapacitors. Therefore, how to fabricate electrode materials with high specific capacitance, fast charge and discharge and certain flexibility has become the focus of current research. Tn this paper, the classification and energy storage mechanism of supercapacitors and the preparation methods and research status of biomass-based carbon materials are reviewed. The key performance evaluation parameters of high-quality load electrodes are analyzed, and the influencing factors of their electrochemical performance are systematically discussed. The future development trend is to integrate different types of energy storage devices into composite energy storage devices to meet the needs of various fields. Composite energy storage devices have greatly improved the comprehensive performance of supercapacitors. Therefore, the development of efficient and stable energy storage technology is of great significance for alleviating energy shortage, reducing environmental pollution and promoting sustainable development. [ABSTRACT FROM AUTHOR]

To improve the electrochemical performance and structural durability of supercapacitors, herein, well-ordered, porous Ni–Zn–Co ternary oxide nanostructures were synthesized by doping Ni to Zn–Co oxide using ultrasonic electrodeposition. Our investigations revealed that Ni–Zn–Co ternary oxide exhibited superior capacity and rate performance when compared to Zn–Co oxide. In particular, the incorporation of 1 mol/L of Ni markedly improved the electrochemical capabilities of the cathode materials. Remarkably, under the influence of ultrasonic power at 500 W, Ni–Zn–Co oxide exhibited a superior mass loading of 6.2 mg/cm2, coupled with exceptional electron transfer efficiency. The growth mechanism and valence composition of Ni–Zn–Co oxides were studied by SEM and XPS analysis. Moreover, electrodes fabricated from Ni–Zn–Co oxide, synthesized via ultrasonic electrodeposition, demonstrated remarkable area capacitance and rate capabilities, achieving an impressive 1.779 F/cm2 at a current density of 3 mA/cm2. Additionally, the supercapacitor incorporating the Ni–Zn–Co oxide electrode exhibited exceptional long-term stability, maintaining a capacity retention rate of 125.2 % over 24,000 cycles in a mild alkaline electrolyte. This study not only contributes to advancing high-performance cathode materials but also offers valuable perspectives on novel techniques for their fabrication. [ABSTRACT FROM AUTHOR]

Nickel-based oxides are selected for their inexpensive cost, well-defined redox activity, and flexibility in adjusting nanostructures via optimization of the synthesis process. This communique explores the field of energy storage for hydrothermally synthesized NiO/ZnO nanowires by analysing their capacitive behaviour. The p-type NiO was successfully built onto the well-ordered mesoporous n-type ZnO matrix, resulting in the formation of p–n heterojunction artefacts with porous nanowire architectures. NiO/ZnO nanowire-based electrodes exhibited much higher electrochemical characteristics than bare NiO nanowires. The heterojunction at the interface between the NiO and ZnO nanoparticles, their specific surface area, as well as their combined synergetic influence, are accountable for the high specific capacitance (C s) of 1135 Fg−1 at a scan rate of 5 mV s−1. NiO/ZnO nanowires show an 18% dip in initial capacitance even after 6000 cycles, indicating excellent capacitance retention and low resistance validated by electrochemical impedance spectroscopy. In addition, the specific capacitance, energy and power density of the solid state asymmetric capacitor that was manufactured by employing NiO/ZnO as the positive electrode and activated carbon as the negative electrode were found to be 87 Fg−1, 23 Whkg−1 and 614 Wkg−1, respectively. The novel electrode based on NiO/ZnO demonstrates excellent electrochemical characteristics all of which point to its promising application in supercapacitor devices. [ABSTRACT FROM AUTHOR]

The phenomenon of poor cycle stability can be effectively solved by using metal–organic frameworks (MOFs) as precursor to obtain oxides. In this work, a layered NiO@NiCo2O4 nanocomposite electrodes were designed from bimetallic (Ni/Co) based bimetallic metal–organic framework (Ni/Co-MOF) by simple hydrothermal method followed by subsequent controlled calcination under air atmosphere at various temperatures for the transition process. XRD and FE-SEM studies were substantiating the formation of MOF derived NiO@NiCo2O4 nanocomposite with layered structure. Interestingly, electrochemical studies shows that MOF derived NiO@NiCo2O4 nanocomposite achieved at the calcination temperature at 300 °C and 400 °C demonstrates high specific capacitance of 2461 F/g and 2180 F/g at the current density of 1 A/g, which keeps the precursor Ni/Co-MOF with high specific capacitance peculiarity of 2250 F/g at 2 A/g. In terms of cycle retention rate, the NiO@NiCo2O4 nanocomposite obtained at 400 °C still has a high retention rate of 78% under the current density of 15 A/g for 4500 cycles. It significantly improved the precursor Ni/Co-MOF low cycle retention rate of only 56% after 1000 cycles. The results show that the metal oxide nanocomposites calcined with MOFs as sacrificial template not only retain the high specific capacitance characteristics of MOFs, but also improve its low cycle stability, which has great potential in electrochemical supercapacitor electrode materials and provides a certain useful reference for the direction of global energy demand. [ABSTRACT FROM AUTHOR]

Electrode materials with high electrochemical activity and outstanding stability is of great significance to improve the performance of supercapacitors. A composite material comprised of core-shell FeCo 2 O 4 @FeCo 2 S 4 nanospheres and MXene nanosheets was synthesized through solvothermal combined with self-assembly. The FeCo 2 O 4 @FeCo 2 S 4 -MXene hybrids as electrode materials exhibit a high specific capacitance of 1090.6 F g−1 at 1 A g−1. All-solid-state supercapacitor using FeCo 2 O 4 @FeCo 2 S 4 -MXene as the positive electrode possesses a high energy density of 49.8 Wh kg−1 at 800 W kg−1and great cycle life with 87.85 % retention over 20,000 cycles at 1 A g−1. The synergistic effect of FeCo 2 O 4 @FeCo 2 S 4 and MXene is the main reason for the exceptional electrochemical performance. FeCo 2 O 4 @FeCo 2 S 4 anchored to MXene prevents the restacking of MXene, while MXene provides a conductive network for accelerating carrier transfer and a skeleton for preventing FeCo 2 O 4 @FeCo 2 S 4 from collapsing during long-term cycling. In view of the above excellent performance, this study provides a feasible idea for future research on high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

Obtaining electrode materials with excellent electrochemical properties is always a challenge in the research of new energy materials. This paper presents a novel composite material prepared using a simple method, which involves embedding core–shell Co3O4@SiO2 nanoparticles onto highly conductive reduced graphene oxide (rGO) with excellent electrochemical performance. The results indicate that the encapsulation of the polymer with the core–shell material enhances the electrochemical performance. In this process, graphene oxide is reduced to reduced graphene oxide (rGO) by the hydrothermal method, and then the prepared core–shell Co3O4@SiO2 nanoparticles are embedded into the network structure of reduced graphene oxide (rGO). In addition, we investigate the optimal mass ratio of the core–shell material Co3O4@SiO2 and rGO in the Co3O4@SiO2/rGO composite. We prepare composites with different ratios of 4:1, 2:1, 4:3, 1:1, and 4:5, Co3O4@SiO2/rGO. The experimental results illustrate that when the current density is 0.4 A/g, the specific capacitance of the composite Co3O4@SiO2/rGO (1:1) is up to 216 F/g, and the volumetric capacitance is 372 F cm−3, which is more than fivefold higher than that of the core–shell material Co3O4@SiO2. Such large performance improvement is mainly attributed to the addition of rGO which can improve the conductivity of the entire composite material and the aggregation of Co3O4@SiO2, thus providing more active sites. This study confirms that the electrochemical properties of graphene oxide can be greatly improved by the combination of hydrothermal reduction graphene oxide with core–shell material Co3O4@SiO2, which provides a certain reference value for the further research of high-performance electrode materials. [ABSTRACT FROM AUTHOR]

Porous carbon materials with regular morphological structure and high heteroatom content have great application potentials in the area of novel energy storage devices. Herein, a family of novel N-doped porous carbon nanofibers are prepared by using a facile CuCl2-mediated activation of a fiber-like N-rich cross-linked polymer, which is readily accessible based on a solvent-thermal reaction between 2,4,6-tris(4-aminophenyl)triazine and dimethyl succinyl succinate. With the assistance of the mild activating reagent (CuCl2), the as-prepared carbon nanofibers (C-X-CuCl2) retain the fibrous morphology of precursor and achieve abundant heteroatom species in the carbon skeleton. The C-X-CuCl2 samples obtain the highest specific surface area of 1964.9 m2 g–1 and the highest N/O doping contents of 10.10 and 15.06 at.%, respectively, all of which are favorable for improving electrochemical performance when applied in supercapacitors. The C-750-CuCl2 electrode delivers the best-performed overall capacitance of 281.5 F g–1 at 0.5 A g–1, and its symmetrical supercapacitors with aqueous electrolyte (6 M KOH) show 93.1% of capacity retention after 10000 charging/discharging operations at 5.0 A g–1. An outstanding energy density of 75.5 Wh kg–1 at a power density of 300 W kg–1 is realized as well for the C-750-CuCl2-based symmetrical supercapacitors when 1-ethyl-3-methylimidazolium tetrafluoroborate is used as the electrolyte. These results indicate that the C-750-CuCl2 carbon nanofiber is a promising material for high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

β-Co(OH)2 nanosheets were prepared in NaNO3 solution by cathode glow discharge electrolysis (CGDE) technique, in which Co sheet and Pt needle were regarded as anode and cathode, respectively. The formation mechanism of β-Co(OH)2 was discussed in detail, and the electrochemical performance was investigated as an electrode material for the pseudocapacitor. The results showed that the obtained β-Co(OH)2 has a single phase of the hexagonal brucite-like nanosheets with an angle of adjacent edges of 120°, side length of 400–500 nm, and thickness of 10-20 nm. The average pore size and specific surface area are 33.1 nm and 122.1 m2 g−1, respectively. The β-Co(OH)2 nanosheets exhibit a high specific capacitance of 335 F g−1 and excellent capacity retention of 77.1% after 3000 charge-discharge cycles at 1 A g−1. CGDE offers a simple, fast, highly effective, and green strategy for the preparation of β-Co(OH)2 nanosheets. The prepared β-Co(OH)2 nanosheets can be used as an alternative electrode material for supercapacitors. Highlights: β-Co(OH)2 nanosheets with hexagonal structure were prepared in NaNO3 solution by using CGDE. The preparation mechanism was discussed based on emission spectra, solution pH and structural characterization. The specific surface area and average pore size of nanosheets are 122.1 m2 g−1 and 33.1 nm, respectively. β-Co(OH)2 nanosheets has 335 F g−1 specific capacitance and 77.1% capacity retention after 3000 cycles. [ABSTRACT FROM AUTHOR]

Graphene, as a highly promising electrode material, has garnered significant attentions due to its remarkable properties. Nevertheless, challenges persist in its commercial application in the field of energy storage and conversion, including easy stacking, inert surface and limited yield. Rational regulation of the morphology, structure and composition of graphene is demonstrated as an effective way to conquer these challenges. Herein, we adopt a facile spray pyrolysis method to achieve large–scale synthesis of 3D crumpled N, O co–doped graphene nanosheets (NO–GNs). By comprehensive characterization and analysis, it is witnessed that our prepared NO–GNs possess unique 3D crumpled morphology as well as abundant structure defects, and achieve successful co–doping of N and O atoms. These optimized morphology, structure and composition effectively increase the specific surface area and substantially enhance the hydrophilicity and reactive activity of NO–GNs, thus leading to markedly improved electrochemical performance towards supercapacitor and oxygen reduction reaction. Evidently, the preparation of NO–GNs not only offers a promising material for advanced energy storage and conversion systems, but also presents a novel but versatile strategy for manufacturing high–performance carbon–based electrodes. Spray pyrolysis guided synthesis of NO–GNs possess unique 3D crumpled shape and abundant structure defects, and effective N and O co–doping, displaying excellent electrochemical performance for supercapacitor and oxygen reduction reaction. [Display omitted] • A facile spray pyrolysis method was proposed to synthesize NO–GNs. • NO–GNs possess optimized morphology, structure and composition. • NO–GNs show enhanced SSA, hydrophilicity and reactive activity. • NO–GNs exhibit excellent performance towards supercapacitor and ORR. [ABSTRACT FROM AUTHOR]

In order to improve the electrochemical performance of layered double hydroxide (LDH) and its application in flexible supercapacitors, MnMoO4 and Nickel-Manganese layered hydroxides (NiMn-LDH) nanosheets were grown on the surface of carbon cloth (CC) by stepwise hydrothermal method, and the NiMn-LDH/MnMoO4/CC composite electrode with nanoarray microstructure was obtained. NiMn-LDH/MnMoO4/CC//AC/CC flexible supercapacitors were assembled by exploiting the flexible electrode and AC/CC as positive and negative electrode materials respectively. The test results of three electrodes show thal the specific capacitance for the electrode is 2 304,5 F ⋅ g-1 at 1 A ⋅ g-1 current density. and the ratio of the flexible electrode attains 78.2% at a current density of 20 A ⋅ g-1. The device presents the maximum energy density of 20.5 Wh ⋅ kg-1, and the maximum power density of 4 804.1 W ⋅ kg-1. After 10000 cycles, the specific capacitance retention rate holds 96.6%. In addition, the specific capacitance of the twisted electrode of the flexible device can still maintain 96.0% of the normal state, showing good flexibility and electrochemical performance. [ABSTRACT FROM AUTHOR]

Construction of the defect structure is a significant approach to optimize the electronic structure and promote the reaction kinetics. However, excessive defects will destroy the structure stability and further inhibit the performance of the electrode material. Herein, a series of copper Prussian blue (CuFe-PBA) nanomaterials with different contents of [Fe-(CN)6] defects are synthesized by a simple chemical coprecipitation method using sodium citrate as a chelating agent and adjusting its ratio with copper ion. The effect of defect regulation on the crystal structure and the difference in the electrochemical properties of CuFe-PBA nanoparticles with different defect contents are studied. The experimental results indicate that reducing the defect content can significantly enhance the energy storage performances of PBAs. CuFe-PBA-2 has the maximum lattice parameters in all samples, ensuring rapid ion migration and electrochemical reaction kinetics, achieving a high specific capacitance of 220 F g–1 at 1 A g–1 and a superior rate capability with 86.4% of the initial specific capacity at 10 A g–1. Furthermore, the minimum [Fe-(CN)6] vacancies increase the load-bearing capacity while guaranteeing the framework's flexibility, thereby enhancing structural stability and ensuring that CuFe-PBA-2 can provide an ultralong cycle life of 107.4% in 10,000 cycles. The hybrid device (CuFe-PBA-2//CNT) receives an energy density of 7.1 Wh kg–1 at a power density of 1.0 kW kg–1 and an energy density of 5.6 Wh kg–1 at a high power density of 7.0 kW kg–1. This work offers a method for regulating defects in CuFe-PBA nanoparticles and provides insight into the relationship between defects and electrochemical performances. [ABSTRACT FROM AUTHOR]

This study investigates the influence of oxygen functional groups in biomass-based activated carbon (AC) as an efficient, high-performance supercapacitor electrode. To create activated carbons with variable oxygen concentration, the surface of produced AC was altered using oxygen as an oxidizing agent at various temperatures. Nitrogen adsorption–desorption isotherms, scanning electron microscopy (SEM), energy dispersive X-ray analyzer (EDX) analysis, thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR) spectroscopy, Boehm titration and X-ray Photoelectron Spectrometer (XPS), are used to characterize the physico-chemical characteristics of the obtained carbons. Afterward, cyclic voltammetry, constant current charge–discharge and electrochemical impedance spectroscopy (EIS) were used to evaluate the electrochemical properties and behavior of ACs based electrodes. Indeed, the oxidative treatment increases the oxygen functional content while reducing the specific surface area. According to the results of the characterization, the electrode test reveals that the modified materials improve the electrochemical properties and enhance the material's double-layer capacitance. The AC treated with oxygen at 623 K displayed outstanding capacitance of 550 F g−1 at specific current of 0.1 A g−1 in NaOH (2 M) electrolyte and exhibits an excellent stability after 1000 cycles with a capacitance retention of 85.5%. In addition to being inexpensive, the prepared materials have excellent electrochemical performance and good stability, which make them appropriate for supercapacitor applications. [ABSTRACT FROM AUTHOR]

As a typical spinel structure material, ZnMn2O4 has been widely researched in the field of electrode materials. However, ZnMn2O4 nanoparticles as electrode materials for supercapacitors have the disadvantages of low conductivity, inferior structural integrity, and easy aggregation, resulting in unsatisfying electrochemical performance. In this work, we use a hydrothermal method and high-temperature calcination to deposit ZnMn2O4 nanoparticles on carbon cloth and explore the influence of hydrothermal reaction time on the deposition morphology and distribution of ZnMn2O4 nanoparticles on carbon cloth. The deposition process of ZnMn2O4 nanoparticles on carbon cloth was analyzed, and a ZMO-9 electrode was deduced to be the most suitable electrode for supercapacitors. A series of electrochemical performance tests show that the ZMO-9 electrode has excellent specific capacitance (specific capacity) (499 F·g−1 (299.4 C·g−1) at a current density of 1 A·g−1) and rate performance (75% capacitance retention at a current density of 12 A·g−1). The assembled asymmetric supercapacitor has an energy density of 46.6 Wh·kg−1 when the power density is 800.1 W·kg−1. This work provides a reference for the structural design of ZnMn2O4 supercapacitor electrode materials and the improvement of electrochemical properties.

In this study, we fabricated a divergent strategy to enhance the electrochemical capacitive properties of electrodes via the cost-effective multistep green and facile electrodeposition and brush coating technique of PEDOT-TiO2/GO/PEDOT-TiO2 composite. The synthesised composite showed both EDLCs and pseudocapacitive behaviour with a good specific capacitance of 501 Fg−1 for sandwiched structure at 1 Ag−1. From the results, synthesized composite has a better ion transportation mechanism which leads to a fast charge–discharge cycle as well as a very high value of power density (500 kW/ kg) suitable for supercapacitor applications. The substance demonstrated excellent electrochemical stability, retaining 94 % of capacitance after 2000 cycles. The obtained nanocomposites were examined by FTIR, XRD, Raman, SEM-EDX and electrochemical analyses such as CV, GCD and EIS analyses. We consider that the highly stable PEDOT-TiO2/GO/PEDOT-TiO2 nanocomposite with super-capacitive behaviours is a very promising material for high-performance electrochemical storage.

Oxygen doping strategy is one of the most effective methods to improve the electrochemical properties of nickel–cobalt phosphide (NiCoP)-based capacitors by adjusting its inherent electronic structure. In this paper, O-doped NiCoP microspheres derived from porous nanostructured nickel metal–organic frameworks (Ni-MOFs) were constructed through solvothermal method followed by phosphorization treatment. The O-doping concentration has a siginificant influence on the rate performance and cycle stability. The optimized O-doped NiCoP electrode material shows a specific capacitance of 632.4 F-g−1 at 1 A-g−1 and a high retention rate of 56.9% at 20 A g−1. The corresponding NiCoP-based asymmetric supercapacitor exhibits a high energy density of 30.1 Wh kg−1 when the power density is 800.9 W kg−1, and can still maintain 82.1% of the initial capacity after 10 000 cycles at 5 A g−1. [ABSTRACT FROM AUTHOR]

In this paper, NiCo2S4 nanoelectrode materials were prepared by a two-step hydrothermal method. Physical and morphological characterization and electrochemical testing revealed that the prepared NiCo2S4 has a sea urchin-like layered three-dimensional network structure, which can fully increase the contact area with the electrolyte, increase the active sites and improve the electrochemical performance. The specific capacitance of the prepared NiCo2S4 nanomaterials reached 717.32 F/g. The cyclic voltammetry test curve as well as galvanostatic charge-discharge (GCD) test curve have perfect symmetry, good material reversibility. Electrochemical impedance spectroscopy (EIS) indicates materials with low impedance. The specific capacitance remained 76.8% after 3000 cycles and the electrochemical stability was good. NiCo2S4 electrode material has excellent electrochemical properties and has a promising application in supercapacitor electrodes. [ABSTRACT FROM AUTHOR]

Supercapacitor with high energy density is highly desired for wearable and flexible smart electronics. For the development of polyaniline-based supercapacitors, it is crucial to improve the long-term stability and specific capacitance. Herein, carbon cloth is etched by metal (oxy)hydroxides to obtain the etched porous carbon cloth (EPCC) for the subsequent controllable grafting of pseudocapacitive polyaniline (PANI). The high specific area, porous structure, and abundant oxygenic groups of EPCC promote the homogeneous deposition of PANI, thus allowing significantly improve specific capacitance, rate capability and electrochemical reversibility. As a result, the EPCC/PANI electrode exhibits excellent areal specific capacitance of 557.5 mF cm−2 in 1 M H2SO4 solution at a current density of 1 mA cm−2 and 242.6 F g−1 at 1 A g−1, with highest energy density of 14.493 Wh kg−1 and highest power density of 1530 W kg−1, respectively. The EPCC/PANI electrode also manifests excellent structural stability, achieving 72.73% capacitance retention after 5000 cycles. This work provides a feasible strategy for the design and construction of flexible energy storage device, which paves the way for the development of wearable electronics in the era of Internet of Things. [ABSTRACT FROM AUTHOR]

Due to the high power density, fast charging speed, and long cycling stability, supercapacitors have been developed rapidly in the area of electrical energy storage devices in the past decades. During the application of supercapacitors, it was found that the properties of the electrode material can greatly affect the supercapacitor performance. Recently, electrode materials based on polymer waste‐derived carbon materials (PWCM) have attracted much attention because of the low preparation cost, good electrode performance, and great benefits for environmental protection. This review aims to describe the recent research development and summarize the investigation state in the field of the PWCM electrodes prepared from polyethylene, polypropylene, polyethylene terephthalate, polystyrene, etc. The preparation method and the electrode performance of the PWCM electrodes are compared. The relationship among the preparation methods, material structure, and electrochemical performance of the PWCM electrodes was explored. Furthermore, the prospects for the application of the PWCMs were provided. [ABSTRACT FROM AUTHOR]

The composite electrode of CoNiSx and Ti3C2Tx MXene was successfully prepared using a one-step hydrothermal method under the in-situ doping of the cobalt element. The effects of in-situ doping of the cobalt element on the micromorphology and electrochemical performance of the electrodes were investigated. After in-situ doping of the cobalt element, NiS with a needle-like structure was converted into a CoNiSx with petal-like structure. The petal-like CoNiSx with a rough surface was very dense and evenly wrapped on the surface and interlamination of Ti3C2Tx, which helped increase the specific surface area and pore volume of the electrode. Under the identical test conditions, CoNiSx@Ti3C2Tx had a higher specific capacitance and capacitance retention than NiS@Ti3C2Tx. This result indicated that the in-situ doping of the cobalt element promoted the electrochemical performance of the electrode. The energy density of the CoNiSx@Ti3C2Tx/nickel foam (NF)//activated carbon (AC)/NF asymmetric supercapacitor device was 59.20 Wh·kg−1 at a power density of 826.73 W·kg−1, which was much higher than that of NiS@Ti3C2Tx/NF//AC/NF. Three CoNiSx@Ti3C2Tx/NF//AC/NF in series were able to illuminate the light emitting diode lamp for about 10 min, which was higher than the 5 min of three NiS@Ti3C2Tx/NF//AC/NF in series under the same condition. The CoNiSx@Ti3C2Tx/NF//AC/NF with high energy density had better application potential in energy storage than the NiS@Ti3C2Tx/NF//AC/NF. [ABSTRACT FROM AUTHOR]

With the fast growth of supercapacitors, there are growing demands for more flexible, stable, safer and cost-effective devices. One of the significant challenges is introducing polymers binders in supercapacitors electrodes to improve durable, malleable and eco-friendly devices. A comprehensive review of electrode preparation and physical and electrochemical properties is crucial to understand how various types of binders contribute to the performance of supercapacitor electrodes. This review summarises the application and effect of polymer binders on their performance as supercapacitor electrodes. Polymer binders have an essential role to play in improving supercapacitor electrodes. Notably, binders act as a glue among the current collectors and active materials and can also increase supercapacitors’ performance and flexibility.

The creation of effective supercapacitor materials is still a priority in the quest to improve energy storage technology. Herein, we present a novel nanocomposite composed of carbon nanoparticles (CNPs) and colloidal SnO2 quantum dots (c-SQDs) or colloidal SnO2 ultrasmall nanoparticles, synthesized through a facile sonochemical-assisted hydrothermal approach. The XRD and XPS analyses confirmed the successful synthesis and composition of the CNP/c-SQD nanocomposite. Morphology studies revealed a well-dispersed morphology with intimate interfacial interactions between the CNPs and c-SQDs. Specifically, the nanocomposite exhibited a high specific capacitance of 569 F/g at a current density of 1 A/g, surpassing conventional carbon-based supercapacitors. Furthermore, the nanocomposite displayed excellent stability with 99% capacity retention after 5000 cycles, indicative of its superior cyclability. These results underscore the potential of the CNP/c-SQD nanocomposite as a promising electrode material for high-performance supercapacitor applications, offering enhanced charge storage capacity, stability, and cyclability. This study contributes to the advancement of energy storage technologies, paving the way for the development of efficient and sustainable electrochemical energy storage devices.

Abstract Due to the high power density, fast charging speed, and long cycling stability, supercapacitors have been developed rapidly in the area of electrical energy storage devices in the past decades. During the application of supercapacitors, it was found that the properties of the electrode material can greatly affect the supercapacitor performance. Recently, electrode materials based on polymer waste‐derived carbon materials (PWCM) have attracted much attention because of the low preparation cost, good electrode performance, and great benefits for environmental protection. This review aims to describe the recent research development and summarize the investigation state in the field of the PWCM electrodes prepared from polyethylene, polypropylene, polyethylene terephthalate, polystyrene, etc. The preparation method and the electrode performance of the PWCM electrodes are compared. The relationship among the preparation methods, material structure, and electrochemical performance of the PWCM electrodes was explored. Furthermore, the prospects for the application of the PWCMs were provided.

Heteroatom-doped porous carbon materials are highly desired for supercapacitors. Herein, we report the preparation of such material from polybenzoxazine (PBZ), a kind of phenolic resin. Four different N- and O-codoped microporous carbon materials were obtained by changing carbonization temperature (600, 700, 800, and 900 °C). Their structures were characterized by scanning electron microscopy (SEM), nitrogen isothermal absorption and desorption, X-ray diffraction (XRD), Raman spectroscopy, elemental analysis and X-ray photoelectron spectroscopy (XPS), and their electrochemical performances were evaluated by cyclovoltammetry (CV) and galvanostatic charge–discharge (GCD) test in a three-electrode system. It was found that the carbon material (C-700) prepared at the carbonization temperature of 700 °C possesses the largest specific surface area (SSA), total pore volume and average pore size among the family, and thus displays the highest specific capacitance with a value of 205 F g−1 at a current density of 0.25 A g−1 and good cycling stability. The work demonstrates that the N- and O-codoped microporous carbon materials with high electrochemical performance can be derived from benzoxazine polymers and are promising for supercapacitor application. [ABSTRACT FROM AUTHOR]

Supercapacitors (SCs) are currently numbered among the most outstanding energy storage and supply devices due to their high power density, durable cycle life, and wide operating temperature range. However, the wide application of SCs is still subject to the low energy density, which drives researchers to extensively look for high-performance electrode materials. In recent years, nickel sulfide-based materials have been widely studied as promising electrode materials for SCs due to their superior theoretical specific capacity, high redox activity, and rapid electric conduction, but the inferior active material utilization efficiency and poor reaction kinetics limit their practical demand in SCs. In this review, we briefly introduced the energy storage mechanism of nickel sulfide electrode materials used in supercapacitors and then launched an overview of improving performance. A particular emphasis is on the modification strategies to accelerate the electron conduction and mass transfer process through carbon recombination, metal heteroatom doping, interfacial electric field construction, exposure of edge active sites and large specific surface area, and building of ion diffusion channels. Finally, we discuss the research orientation of nickel sulfide-based electrode materials. [ABSTRACT FROM AUTHOR]

Due to their rich and adjustable porous network structure, paper-based functional materials have become a research hotspot in the field of energy storage. However, reasonably designing and making full use of the rich pore structure of paper-based materials to improve the electrochemical performance of paper-based energy storage devices still faces many challenges. Herein, we propose a structure engineering technique to develop a conductive integrated gradient porous paper-based (CIGPP) supercapacitor, and the kinetics process for the influence of gradient holes on the electrochemical performance of the CIGPP is investigated through experimental tests and COMSOL simulations. All results indicate that the gradient holes endow the CIGPP with an enhanced electrochemical performance. Specifically, the CIGPP shows a significant improvement in the specific capacitance, displays rich frequency response characteristics for electrolyte ions, and exhibits a good rate performance. Also, the CIGPP supercapacitor exhibits a low self-discharge and maintains a stable electrochemical performance in different electrolyte environments because of gradient holes. More importantly, when the CIGPP is used as a substrate to fabricate a CIGPP-PANI hybrid, it still maintains good electrochemical properties. In addition, the CIGPP supercapacitor also shows excellent stability and sensitivity for monitoring human motion and deaf-mute voicing, showing potential application prospects. This study provides a reference and feasible way for the design of structure-engineered integrated paper-based energy storage devices with outstanding comprehensive electrochemical performance. [ABSTRACT FROM AUTHOR]

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With the development of the energy industry, electrochemical energy storage technology is increasingly involved in developing innovations in the field. The materials of the electrode have a significant influence on the performance of energy storage devices. For this purpose, two-dimensional MXene with excellent electrical conductivity, mechanical strength, and a variety of possible surface-active terminations are attracting much attention. In the present work, S-decorated d-Mo 2 CT x (d-Mo 2 CT x- -S) is designed. The first-principles calculations reveal that it may possess good energy storage characteristics. Due to the decoration with S, unique morphology and structure are obtained, conferring stability, optimized Li+ storage, improved charge transport, and lithium-ion adsorption capabilities. Compared with d-Mo 2 CT x , d-Mo 2 CT x- -S exhibits higher discharge capacity (623 mAh g−1 at 1 A g−1) as lithium-ion electrode material and higher specific capacitance (561 F g−1 at 1 A g−1). As a supercapacitor, the material also shows excellent cyclic stability (20,000 charge-discharge cycles). This work may inspire the exploration of other MXene and new surface functionalization methods to improve the performance of MXene as electrode materials for new energy devices. [ABSTRACT FROM AUTHOR]

• Sludge-derived humic acid is converted into carbon materials. • Low-cost energy storage materials can be prepared. • The purified humic acid-based carbon material has better performance. • Optimized material exhibits high performance in supercapacitors. As one of the main methods for sludge treatment, recovery of renewable biogas energy by anaerobic digestion (AD) is a promising strategy to deal with the conflict between carbon neutralization and sharply increase of sewage sludge. Humic acid (HA) in sludge is a major inhibitor of biogas yields and needs to be removed or pretreated. However, as the graphene oxide-like material, HA is an ideal precursor for the preparation of energy storage materials with high performance. Based on that, this study i) proposes the extraction and utilization of HA in sludge, ii) discusses the feasibility of HA-based materials after thermal reduction as electrodes for supercapacitor, and iii) investigates the factors with positive influences on the structure and electrochemical performance. It reveals that, with a synergistic effect of purification and activation at a low mass ratio, the HA-based material exhibits superior capacitive performance with the highest specific capacitance of 186.7 F/g (at 0.05 A/g), as well as excellent rate capability and cycling stability. Sludge is verified a cheaper and more abundant precursor resource of HA for energy storage application. The results of this study are expected to provide a new green, energy-efficiency and sustainability way for sludge treatment, which has the double benefits: efficient conversion and capture of bio-energy during AD process, and high value-added utilization of HA for supercapacitor. [ABSTRACT FROM AUTHOR]

Pitch is a high-quality carbon material precursor due to the characteristics of high carbon and low ash. It is used in the preparation of supercapacitor electrode materials, which not only has a significant effect on widening the application pathway of pitch, but also on the economic efficiency of the coal chemical process.The influence of specific surface area, pore structure and surface properties of carbon materials on the performance of supercapacitors was firstly introduced, and the influence of porous carbon preparation methods（activation method, template method） and pitch pretreatment methods（component separation, pre-oxidation, catalytic polymerization, high temperature polymerization, et al.） on the structure and electrochemical properties of the prepared carbon materials were reviewed. Finally, some further insights into the development of pitch-based porous carbon are proposed. [ABSTRACT FROM AUTHOR]