Free-standing Supercapacitor Research Articles

Cellulose Nanofiber-Supported Electrochemical Percolation of Capacitive Nanomaterials with 0D, 1D, and 2D Structures.

Cellulose nanofiber (CNF) represents a promising support material to strengthen the mechanical property of free-standing supercapacitor electrodes comprised of conducting nanomaterials. Although efforts have been focused on improving the performance of the CNF-supported electrode, the percolation of capacitive nanomaterials within the insulating CNF matrix, and its correlation with the nanomaterial's dimensionality are still underexplored. In this work, membrane supercapacitor electrodes are fabricated by incorporating CNF with 0D, 1D, and 2D capacitive nanocarbons respectively to study the impact of their dimensionality. It is found that the percolation pathway of the nanocarbons is dependent on their dimensionality. By introducing a new definition termed as electrochemical percolation threshold, the threshold weight percentages to realize effective electrochemical percolation are determined to be 60.0, 14.3, and 66.7% for 0D, 1D, and 2D nanocarbons, respectively. Increasing the weight percentage beyond the threshold typically results in improved electrochemical percolation but reduced mechanical strength, and both trends are dependent on the nanocarbon's dimensionality. The results provide guidance to design efficient and robust CNF-supported supercapacitor electrodes by controlling the dimensionality and density of the active material. The insights regarding the electrochemical percolation threshold can be applied to other energy-storage nanomaterials to advance the development of insulator-supported supercapacitors.

Effect of processing parameters on the properties of carbon paper as a free-standing supercapacitor electrode

As newly emerging energy storage devices, supercapacitors are being investigated thoroughly by researchers. Free-standing electrode is one of the major research focuses in this area, which not only avoids the use of resistive binders but also simplifies device assembly. The study describes the synthesis and study of carbon fiber-based carbon carbon composite paper (heat treated to different temperatures) as a free-standing supercapacitor electrode. Due to the inert nature of carbon paper, it was activated to create defect sites and to increase the specific surface area. Electrochemical studies suggested that activated carbon paper heat treated to 750°C (ACP-750) exhibited the highest areal capacitance of 11.4 F/cm2 (422.2 F/g) at the current density 2.5 mA/cm2 (0.09 A/g), probably due to the generation of larger number of defect sites (as depicted by XRD and RAMAN studies). ACP-750 electrode was used to fabricate the solid-state symmetric supercapacitor device that exhibited an energy density 0.77 Wh/cm2 at a power density of 2.34 W/cm2. The electrode was allowed to age (ACPA-750), after which it exhibited enhanced specific capacitance of 16.8 F/cm2 (622.2 F/g) at a current density 2.5 mA/cm2. ACPA-750//ACPA-750 device delivered maximum energy density of 1.66Wh/cm2 at a power density of 3 W/cm2. The device exhibited a coulombic efficiency of 96.1% and capacitance retention of 89% after 10,000 cycles.

Improving the capacitive performance of wood-derived carbon monolith by anchoring heteroatom-doped carbon nanotubes in the vessels via in situ chemical vapor deposition

Wood, with high carbon contents and abundant vertically oriented channels, has unique advantages in preparing high mass-loading carbon-based freestanding supercapacitor electrodes. However, there is considerable room for enhancing the capacitive performance of wood-derived carbon electrodes. A one-step chemical vapor deposition (CVD) method mediated by dicyandiamide using iron-based nanoparticles as catalysts was proposed to enhance the utilization of vertical channels in wood-based carbon electrodes and improve their pore structure and chemical composition. This approach aimed to fabricate composite electrodes with enhanced mass loading, interwoven conductive carbon nanotube networks, well-developed hierarchical porous structure, and abundant nitrogen/oxygen-containing functional groups. The effect of CVD temperature on the physical/chemical properties and capacitance performance of the composite material was investigated. Consequently, the optimal electrode (CW/NCNTs-800) attained a competitive initial specific capacitance of 5762 mF cm−2 at 5 mA cm−2 and demonstrated a satisfactory rate performance with the specific capacitance of 3520 mF cm−2 at 300 mA cm−2. In addition, the durable electrode demonstrated commendable cycle stability, maintaining a capacitance retention of 93 % through 30,000 cycles at 30 mA cm−2. This study on wood-derived high mass-loading supercapacitor electrodes can provide a novel perspective on the application of high-performance energy storage devices.

Fabrication of highly flexible, wearable, free-standing symmetric supercapacitors with high voltage operation enabled by hierarchical graphene/cerium oxide/polypyrrole hybrid films

Flexible, free-standing supercapacitors play a significant role in the development of future wearable energy storage devices. Herein, we successfully fabricated the highly flexible and free-standing graphene/cerium oxide/polypyrrole hybrid films by thermal reduction of graphene oxide (GO) followed by the sol–gel synthesis of CeO2 and then the addition of PPy. By regulating oxygen functional groups in GO, the electronic conductivity and electroactive sites of the hybrid films are significantly controlled, leading to enhanced energy storage capability. Finally, a symmetric flexible supercapacitor (FSC) device was developed using the prepared films as electrodes. Resulting, the integrated symmetric GO-400/CeO2/PPy FSC manifests excellent areal capacitance of 49.0 mF cm−2 at 1 mA cm−2, with a durability of 83.1 % over 10,000 cycles. Specifically, the FSC exhibited capacitance retention of 77.2 % after 10,000 cycles under bending state with exceptional rate ability. Meanwhile, an impressive energy density of 19.69 µW h cm−2 was attained at a power density of 0.85 mW cm−2. Evidently, the synergistic interactions between GO and PPy nanosheets, along with CeO2 favour the rapid electron movement of electrode material for next-generation wearable, portable electronics.

A rigid free-standing supercapacitor electrode material made from fat coal-based activated carbon foam

A free-standing electrode material is a competitive candidate for supercapacitor due to its excellent capacity and volumetric energy density. Currently, most of the studies are focused on the preparations and performances of flexible free-standing electrode materials, whereas few on the development of rigid free-standing electrode materials. Herein, a vitrinite concentrate of fat coal is used as a raw material and carbon black as an addition agent to prepare a carbon foam by way of high-pressure pyrolysis. The prepared carbon foam is activated by KOH solution to further achieve an activated carbon foam by which we have fabricated a rigid free-standing electrode material. The assembled symmetric device with the rigid free-standing electrode material demonstrates an extremely high areal specific capacitance of 2304.41 mF cm−2 at 4 mA cm−2, an outstanding cycling stability of 100 % after 40 000 cycles, and an excellent volume energy density of 10.23 mWh cm−3 at 31.78 mW cm−3. These fascinating electrochemical performances of the electrode material are attributed to unique 3D interconnected porous structure of the activated carbon foam. The micron-sized 3D interconnected pores facilitate the transport of electrolyte ions within the electrodes. Meanwhile, micropores on the 3D interconnected pore wall provide abundant active sites for electrolyte ions.

Hierarchical porous 3D Ni3N-CoN/NC heterojunction nanosheets with nitrogen vacancies for high-performance flexible supercapacitor

In the realm of everyday existence, the allure of flexible portable electronic devices has captured widespread attention. Consequently, the imperative to conceive and fabricate flexible energy storage/conversion systems assumes paramount significance. Transition metal nitrides (TMNs), distinguished by their extraordinary electrochemical properties, emerge as compelling candidates for electrode materials in high-performance energy storage devices. This study undertakes the synthesis of three-dimensional Ni3N-CoN/NC heterojunction nanosheets via a meticulous two-step in situ growth process involving metal organic frameworks (MOFs) on carbon cloth (CC), succeeded by annealing in an ammonia-rich environment. The ensuing nitridation engenders copious ion pathways, engrossing a considerable specific surface area of 233.2 m2 g−1 and endowing nitrogen vacancies in abundance. The augmented conductivity of the nitrogen-vacancy-rich heterojunction is corroborated through density functional theory calculations. Employed as a flexible freestanding supercapacitor electrode, the Ni3N-CoN/NC/CC configuration evinces a marked enhancement in electrochemical performance attributable to its superior intrinsic conductivity and heightened active sites. Notably, the synthesized Ni3N-CoN/NC/CC flexible electrode showcases a remarkable specific capacitance of 468.3 mA h g−1 at a current density of 3 A g−1. Moreover, the integration of the Ni3N-CoN/NC/CC cathode with an activated carbon (AC) anode in a flexible asymmetric supercapacitor (ASC) yields an impressive energy density of 0.2144 mWh cm−2 and a maximum power density of 80 mW cm−2, exhibiting exceptional cycling stability of 92.3% even after 15,000 cycles. The exceptional performance exhibited by the synthesized freestanding Ni3N-CoN/NC/CC composite underscores its tremendous potential in the development of flexible energy storage devices.

CoCx‑induced interfacial octahedral Co2+ sites of NiCo-LDH electrode with improved faradic reactivity toward high-performance supercapacitor

Battery-like electrode materials are characterized by large theoretical capacitance but suffer from poor surface reactivity and insufficient electroactive sites thus limiting their practical charge storage capacity. To overcome this challenge, an effective strategy for vacancy modulation on battery-like electrode materials is necessary. Herein, we report for the first time an elaborately designed three-dimensional (3D) hierarchical heterostructure consisting of CoCx@NiCo-LDH on conductive nickel foam as a freestanding supercapacitor electrode. Benefiting from the weakening of the coordination of CoO bonds, the CoCx structure induces in-situ reconstruction of the NiCo-LDH lattice, resulting in the formation of abundant oxygen vacancies (interfacial octahedral Co2+ sites) that lower the OH− adsorption energy as determined by the density functional theory (DFT) calculation. The resulting CoCx@NiCo-LDH/NF electrode exhibits an ultrahigh rate capability (2330 mF cm−2 at 0.3 mA cm−2, with capacitance retention of 51.5 % at 30 mA cm−2) and remarkable cycling performance (capacitance retention of 81.6 % after 10,000 cycles). Additionally, the assembled asymmetric devices deliver an extremely high energy density of 246 μWh cm−2 at the power density of 798 μW cm−2, with 87.8 % capacitance retention after 10,000 cycles at 8 mA cm−2. Overall, this study presents a simple yet effective strategy to construct high-performance battery-like electrodes for potential applications in energy storage, transportation, and communication.

Highly foldable and free-standing supercapacitor based on hierarchical and hollow MOF-anchored cellulose acetate carbon nanofibers

Flexible electrode materials have achieved great breakthroughs during the past decades. However, many challenges remain such as how to overcome the frangibility and enhance the flexibility, and advance the high specific capacitance. We fabricated a free-standing, foldable, and conductive cellulose acetate (CA)-based metal-organic framework (MOF) composites by facile electrospinning carbonization and co-precipitation method. The sustainable cellulose derivative provides a flexible matrix, which contains hierarchically porous and ample redox activities. The intermolecular interaction is enhanced for coordination between exposed hydroxyl on deacetylated CA and metal ions, thus reduce the fracture of the CA nanofibers. Importantly, multi-layer heterojunction structure and honeycomb-like MOF nanosheets with reversibly flexible deformation create interlamellar pathways to improve the bending resistance of nanofibers. The controlled Co/Zn ion concentration could effectively modulate spatial distribution of Co/Zn MOF to thus generate different conductive channels. The asymmetric flexible supercapacitor based on Ni/Co LDH@ Co/Zn NC@CDCP-N electrode material gives high specific capacitance (175.2 F g−1 at 1 A g−1) and outstanding energy density (54.8 W h kg−1) at high power density (985.5W kg−1). Our work paves a way to facile fabrication of flexible and free-standing electrode materials for practical flexible energy storage, such as artificial electronic skin and soft wearable electronics.

A morphology control engineered strategy of Ti3C2Tx/sulfated cellulose nanofibril composite film towards high-performance flexible supercapacitor electrode

2D Ti3C2Tx MXene is an ideal material for fabricating supercapacitor electrodes due to its excellent physical-chemical properties. However, the inherent self-stacking, narrow interlayer spacing, and low general mechanical strength limit its application in flexible supercapacitors. Herein, facile structural engineering strategies by drying (vacuum drying, freeze drying, and spin drying) were proposed to fabricate 3D high-performance Ti3C2Tx/sulfated cellulose nanofibril (SCNF) self-supporting film supercapacitor electrodes. Compared with other composite films, the freeze-dried Ti3C2Tx/SCNF composite film exhibited a looser interlayer structure with more space which was conducive to charge storage and ion transport in the electrolyte. Therefore, the freeze-dried Ti3C2Tx/SCNF composite film exhibited a higher specific capacitance (220 F/g) compared to the vacuum-dried Ti3C2Tx/SCNF composite film (191 F/g) and the spin-dried Ti3C2Tx/SCNF composite film (211 F/g). After 5000 cycles, the capacitance retention rate of the freeze-dried Ti3C2Tx/SCNF film electrode was close to 100 %, showing excellent cycle performance. Meanwhile, the tensile strength of freeze-dried Ti3C2Tx/SCNF composite film (13.7 MPa) was much greater than that of the pure film (7.4 MPa). This work demonstrated a facile strategy for control of Ti3C2Tx/SCNF composite film interlayer structure by drying for fabricating well-designed structured flexible and free-standing supercapacitor electrodes.

Rational construction of hierarchical nanocomposites by growing dense polyaniline nanoarrays on carbon black-functionalized carbon nanofiber backbone for freestanding supercapacitor electrodes

Designing freestanding electrodes for supercapacitors has attracted tremendous attention since avoiding the use of inactive additives is cost-effective and process-efficient for the industrialization and commercialization of supercapacitors. To accommodate the vigorous electrochemical process and facilitate charge transfer, robust and conductive backbones are required to fabricate freestanding electrodes. Herein, a carbon black (CB)-functionalized electrospun carbon nanofiber (CNF) backbone is fabricated for growing redox-active dense polyaniline (PANI) nanoarrays to construct hierarchical carbon black/carbon nanofiber/PANI nanocomposites (CCNFP) as freestanding supercapacitor electrodes. The CB particles act as nanofillers to functionalize the CNF backbone, not only providing additional conductive networks and pores inside each nanofiber but also increasing the surface roughness to facilitate PANI deposition; whereas PANI nanoarrays offer pseudocapacitive properties and improve the wettability of the electrodes. The synthesized CCNF7P24 electrode exhibits a high specific capacitance of 1062.7 F g−1 and excellent retention of 72.2 % at current densities of 1 and 20 A g−1, respectively. A symmetric supercapacitor constructed from two freestanding CCNF7P24 electrodes delivered a maximum energy density of 54.3 Wh kg−1, benefiting from the excellent electrochemical performance of the electrodes. This work provides a reliable approach to fabricating nanofiber-based hierarchical composites for freestanding electrodes.

Challenges and opportunities in free-standing supercapacitors research

The design of commercial supercapacitors has remained largely unchanged since the 1970s, comprising powdered electrodes housed in rigid metal cylinders or pouches. To power the next generation of integrated technologies, an evolution in supercapacitor materials and design is needed to create multifunctional materials that allow energy storage while imparting additional material properties (e.g., flexibility and strength). Conductive free-standing electrodes produced from fibers or 3D printed materials offer this opportunity as their intrinsic mechanical properties can be transferred to the supercapacitor. Additionally, their conductive nature allows for the removal of binders, conductive agents, and current collectors from the supercapacitor devices, lowering their economic and environmental cost. In this Perspective, we summarize the recent progress on free-standing supercapacitors from new methods to create free-standing electrodes to novel applications for these devices, together with a detailed discussion and analysis on their electrochemical performance and physicochemical and mechanical properties. Furthermore, the potential directions and prospects of future research in developing free-standing supercapacitors are proposed.

Flexible MnO-encapsulated carbon nanofiber composites as high-performance freestanding supercapacitor electrodes

Flexible MnO-encapsulated carbon nanofiber composites as high-performance freestanding supercapacitor electrodes

Cactus-like NiCo2O4@Nickel-plated fabric nano-flowers as flexible free-standing supercapacitor electrode

Binary transition-metal oxides have caused wide public concern for energy storage as a result of its higher electrical conduction and electrochemical activity compared to single metal oxides in the past few years. However, its practical applications are severely limited by poor specific capacitance and cycling stability. Recently, an effective strategy for enhancing the electrochemical performance of supercapacitors has been demonstrated by proper structural design and optimization of material. Herein, cactus-like NiCo2O4@NPF nano-flower flexible supercapacitor electrodes assembled from 1D NiCo2O4 nanoneedles on 2D hollow metal networks by simple hydrothermal and calcination treatment. The unique nano-flower structure can construct multi-dimensional channels, which facilitate the transport of electrons and ions and significantly enhances the reaction kinetics at the interface between the electrolyte and the active materials. The NiCo2O4@NPF-1 electrode displays an outstanding electrochemical energy storage performance and the specific capacitance is 1106 F g−1 at 1 A g−1. Besides, the composite electrode exhibits a distinguished rate capability (633 F g−1 at 50 A g−1) and favorable cyclability (capacity retention of 92.2% after 2000 cycles). These exceptional results recommend that as-assembled NiCo2O4@NPF nano-flower hybrid material could be a hopeful contender for multifunctional flexible supercapacitor electrodes.

Multifunction Web-like Polymeric Network Bacterial Cellulose Derived from SCOBY as Both Electrodes and Electrolytes for Pliable and Low-Cost Supercapacitor.

In this work, bacterial cellulose (BC)-based polymer derived from a symbiotic culture of bacteria and yeast (SCOBY) are optimized as both electrodes and electrolytes to fabricate a flexible and free-standing supercapacitor. BC is a multifunction and versatile polymer. Montmorillonite (MMT) and sodium bromide (NaBr) are used to improve mechanical strength and as the ionic source, respectively. From XRD analysis, it is found that the addition of MMT and NaBr has reduced the crystallinity of the electrolyte. Most interaction within the electrolyte happens in the region of the OH band, as verified using FTIR analysis. A maximum room temperature conductivity of (1.09 ± 0.02) × 10−3 S/cm is achieved with 30 wt.% NaBr. The highest conducting SCOBY-based electrolytes have a decompose voltage and ionic transference number of 1.48 V and 0.97, respectively. The multiwalled carbon nanotube is employed as the active material held by the fibrous network of BC. Cyclic voltammetry shows a rectangular shape CV plot with the absence of a redox peak. The supercapacitor is charged and discharged in a zig-zag-shaped Perspex plate for 1000 cycles with a decent performance.

Electrochemical activity of triple-layered boron-containing carbon nanofibers with hollow channels in supercapacitors

Triple-layered boron-containing carbon nanofibers (CNFs) with hollow channels (PPMPB) are fabricated via step-by-step electrospinning for high-performance freestanding supercapacitors. Polyacrylonitrile (PAN)-based CNFs in the first layer are chosen as the support layer material because of their excellent chemical stability and electrospinnability. The well-developed hollow channels provided fast ion diffusion in the second layer of PAN/poly(methyl methacrylate) (PMMA)-based CNFs. The surface boron functional groups constituting the third layer contribute to the pseudo-capacitance. The symmetric supercapacitor of the PPMPB electrodes delivers a maximum specific capacitance of 180 Fg−1 at 1 mAcm−2, a high energy density of 22.38 Whkg−1 at a power density of 400 Wkg−1, and an excellent retention rate of 96% after 10,000 cycles in aqueous solution. The excellent electrochemical performance is attributed to the unique sandwich nanostructure with a three-layer structure, in which the factors representing the electrochemical properties of each layer do not interfere with each other. Therefore, a moderate amount of boron and the high surface area of the triple-layer structured PPMPB can be fully utilized as an excellent conductive network and electroactive sites, which is expected in a high-performance supercapacitor electrode.

High-performance freestanding supercapacitor electrode based on polypyrrole coated nickel cobalt sulfide nanostructures

In the present work, we report the successful fabrication of dandelion-like Nickel–Cobalt Sulfide@Polypyrrole microspheres through the hydrothermal method and its possible application as a binder-free electrode in supercapacitors. This electrode exhibited low charge transfer resistance with a remarkable specific capacitance of 2554.9 F g−1 at 2.54 A g−1, in addition to considerable cycle life stability. Also, an asymmetric device was prepared using NiCo2S4@PPy/NF as positive and rGO/NF as negative electrodes. This asymmetric supercapacitor exhibited a specific capacitance of 98.9 F g−1 at 1.84 A g−1 and delivered an energy density of 35.17 Wh kg−1 at a power density of 1472 W kg−1. Such a remarkable performance can be originated from the synergy effect of NiCo2S4 and PPy and the direct deposition of the composite on the current collector. Our findings suggest the dandelion-like NiCo2S4@PPy as a promising material for making high-performance supercapacitors.

Highly flexible, freestanding supercapacitor electrodes based on hollow hierarchical porous carbon nanofibers bridged by carbon nanotubes

Supercapacitors are considered to be the next generation of wearable energy storage devices because of reliable safety, high power density, and long cycle life, but the flexibility and energy density limit their practical applications. Herein, the flexible hollow hierarchical porous carbon nanofibers bridged by carbon nanotubes (HPCNFs@CNTs) are designed and constructed, followed by polyaniline (PANI) decorating to fabricate PANI@HPCNFs@CNTs. The synergistic effect of the hollow structure, hierarchical pores, in-situ nitrogen doping, and the bridging structure endows the HPCNFs@CNTs with a high specific capacitance of 461.0F g−1 (207.4 mF cm−2) while maintaining glorious flexibility under various deformation states. Besides, PANI@HPCNFs@CNTs possesses a high specific capacitance of 629.1F g−1 (405.2 mF cm−2) and remarkable cycle stability with 88.5 % capacitance retention after 5000 charging-discharging cycles. The device assembled by PANI@HPCNFs@CNTs renders an ultra-high energy density of 23.3 Wh kg−1 at a power density of 202.7 W kg−1. Furthermore, the device provides remarkable cycle stability and high-rate capability with a capacity retention of 91.3 % after 5000 cycles at 5 A g−1 and 76.7 % at 10 A g−1, respectively, demonstrating a tremendous potential to construct high-performance flexible energy storage devices.

Three-dimensional, heteroatom-enriched, porous carbon nanofiber flexible paper for free-standing supercapacitor electrode materials derived from microalgae oil

Polyacrylonitrile (PAN) based carbon nanofiber (CNF) papers have unique physicochemical properties including flexibility, good electrical conductivities, and excellent mechanical properties for supercapacitor electrodes. However, their surface-to-weight ratios and density of active sites on the surface are much poorer than those of other active carbons. Herein, a simple, renewable, multifunctional, and effective way is described to fabricate three-dimensional (3D) heteroatom-enriched porous PAN-based CNF papers by adding a moderate amount of microalgae-derived oil that has a large fraction of light compounds and nitrogen- and oxygen-containing functional components. CNF papers with enhanced porosity and large specific surface area, unique pore structure, and 3D heteroatom-enriched surfaces were successfully fabricated by stabilization and carbonization of PAN nanofibers with the algae oil. The as-fabricated algal-30% CNF paper is scalable and highly flexible as a free-standing supercapacitor electrode material and can deliver a specific capacitance of 272 F/g under a scan rate of 10 mV/s with noticeably high charge-discharge cycling stability, with 94% retained even after 10,000 cycles. The fabrication mechanism and the enhancement of the electrochemical behaviors of three-dimensional, heteroatom-enriched, porous CNF papers are proposed. Our work underlines the promise of algae oil-modified PAN-based CNF papers for high-capacity supercapacitor electrode materials.

Novel In Situ Synthesis of Freestanding Carbonized ZIF67/Polymer Nanofiber Electrodes for Supercapacitors via Electrospinning and Pyrolysis Techniques.

Zeolitic imidazolate framework-67 (ZIF67) has been regarded as an effective energy storage material due to its high surface area and electroactive cobalt center. Carbonizing ZIF67 can enhance electrical conductivity by converting 2-methylimidazole (2-melm) to carbon with cobalt doping. In this work, a novel in situ electrospinning is proposed to fabricate carbonized ZIF67 on carbon fiber (C67@PAN-OC) as a freestanding supercapacitor electrode. Polyacrylonitrile solution containing a cobalt precursor is used for electrospinning, and produced fibers are immersed in 2-melm to form ZIF67. Individually grown carbonized ZIF67 on carbon fiber is obtained using the in situ electrospinning method, while the one-body mixed carbon electrode is formed using the ex situ electrospinning method. A highest specific capacitance (CF) of 386.3 F/g at 20 mV/s is obtained for the in situ synthesized C67@PAN-OC electrode due to the largest electrochemical surface area and the smallest resistance, while the ex situ synthesized electrode only shows a CF value of 27.7 F/g. A symmetric supercapacitor (SSC) assembled using the optimized C67@PAN-OC electrodes and gel electrolytes shows a maximum energy density of 9.64 kWh/kg at 0.55 kW/kg and a CF retention of 59.5% after 1000 times charge/discharge process. A CF retention of 75.6% after bending 100 times is also obtained for SSC.

Self-organized hierarchically porous carbon coated on carbon cloth for high-performance freestanding supercapacitor electrodes

In this work, a facile method is proposed for the fabrication of self-organized hierarchically porous carbon coated on carbon cloth. The method is based on the thermal treatment of potassium citrate gel, which is derived from mixture of citric acid and potassium hydroxide. The as-prepared porous carbon derived from citrate gel generally covers carbon cloth with fine morphological properties and the sample can be directly used as an electrode material for supercapacitor. In a three-electrode configuration, the optimized electrode exhibits a remarkable specific capacitance of 379.5F g−1 at a current density of 1 A g−1. In addition, a good cycle stability with capacity retention of 97% is achieved after 10,000 cycles at a current density of 10 A g−1. Moreover, a symmetric supercapacitor is prepared by using the as-prepared electrode. The supercapacitor shows a high energy density of 0.69 mWh cm−3 at a power density of 4.91 mW cm−3 and good cycle durability and mechanical flexibility. The porous carbon material reported in this work shows potential as electrode for flexible all-solid-state supercapacitors.