Excellent Supercapacitive Performance Research Articles

In-situ doping-induced lattice strain of NiCoP/S nanocrystals for robust wide pH hydrogen evolution electrocatalysis and supercapacitor

Developing high-efficiency multifunctional nanomaterials is promising for wide pH hydrogen evolution reaction (HER) and energy storage but still challenging. Herein, a novel in-situ doping-induced lattice strain strategy of NiCoP/S nanocrystals (NCs) was proposed through using seed crystal conversion approach with NiCo2S4 spinel as precursor. The small amount of S atoms in NiCoP/S NCs perturbed the local electronic structure, leading to the atomic position shift of the nearest neighbor in the protocell and the nanoscale lattice strain, which optimized the H* adsorption free energy and activated H2O molecules, resulting the dramatically elevated HER performance within a wide pH range. Especially, the NiCoP/S NCs displayed better HER electrocatalytic activity than comical 20% Pt/C at high current density in 1 M KOH and natural seawater: it only needed 266 mV vs. reversible hydrogen electrode (RHE) and 660 mV vs. RHE to arrive the current density of 350 mA cm−2 in 1 M KOH and natural seawater, indicating the application prospect for industrial high current. Besides, NiCoP/S NCs also displayed excellent supercapacitor performance: it showed high specific capacity of 2229.9 F g−1 at 1 A g−1 and energy density of 87.49 Wh kg−1, when assembled into an all-solid-state flexible device, exceeding performance of most transition metal phosphides. This work provides new insights into the regulation in electronic structure and lattice strain for electrocatalytic and energy storage applications.

Simple and efficient CVD synthesis of graphitic P-doped 3D cubic ordered mesoporous carbon at low temperature with excellent supercapacitor performance

Heteroatom doping is a promising strategy for improving the electrochemical performance of carbon materials. Herein, we spotlight an advantageous, simple, and efficient CVD synthesis of P-doped 3D cubic ordered mesoporous carbon (POMC) for the first time. The POMC was prepared by pyrolysis of acetylene/triphenylphosphine (C2H2/Ph3P) mixture at relatively low temperature over Fe-KIT-6 as a sacrificial template. The ensuing P-doped OMC showed an enhanced porous texture than an undoped counterpart with a specific surface area of 403.5 m2/g, pore volume of 0.545 cm3/g, average pore size of 4.64 nm and suitable heteroatom functionalities with P and O contents of 0.13% and 9.83%, correspondingly. The obtained POMC exhibited a much higher specific capacitance of 288F/g at 0.2 A/g (175F/g for OMC), good cyclic stability of 97.6 %, and good rate capability than pristine OMC in 6 M KOH. It is equivalent to or improved than various stated mono doped and even dual doped porous carbon electrodes. Furthermore, a symmetric supercapacitor (POMC//POMC) was fabricated with 1 M Na2SO4 aqueous neutral electrolyte exhibits high cycling stability (89.3%) even with a wide potential window (2.0 V) and offers a relatively high energy density (10.01 Wh/kg) with a power density of 300 W/kg.

Ultrafast Microwave Assisted Synthesis of Three-Dimensional Graphene Material and its Excellent Performance for Supercapacitors

Ultrafast microwave assisted synthesis of three-dimensional graphene via one-step microwave irradiation method has been reported. The milligram-grade highly conductive acetylene black as the power conversion center, rapidly converts microwave energy into heat and forms local instantaneous high temperature, resulting in partial detachment of functional groups and promoting the recovery of the conductive network of the carbon layers within a few seconds. Interestingly, the nano-scaled acetylene black was found to be tightly bound to the lamella of the 3D graphene, the 3D graphene containing the few acetylene black exhibited a typical double-layer behavior with outstanding specific capacitance of 279.8 F g−1 at 0.5 A g−1 and high capacitance retention over 85% after 20000 cycles. A symmetric supercapacitor assembled in organic electrolyte shown a wide voltage window (0 - 2 V). These satisfactory results provide a potential solution for the manufacture of high-capacity electrochemical energy storage.

Preparation and characterization of zinc–aluminum layered doubled hydroxide/ graphene nanosheets composite for supercapacitor electrode

Graphene nanosheets were synthesized using the liquid phase exfoliation technique while zinc-aluminum layered doubled hydroxides (ZnAl-LDHs) were fabricated using the chemical bath deposition method. A composite of graphene/Zn–Al LDHs was synthesized and used as an electrode for the supercapacitor . ZnAl-LDHs present a well-standing nanosheets-like structure that covered the entire area of the substrate. The thickness of these nanosheets was found to be between 60 and 80 nm. The SEM images of the graphene/Zn–Al LDHs composite display graphene nanosheets next to the LDHs nanosheets. The optical band gap of this composite was found to be about 4 eV. The obtained electrode exhibited excellent supercapacitive performances with the highest specific capacitance of ∼ 140 F / g along with the maximum energy, and power densities of 15.359 k W K g − 1 and 2.016 W h K g − 1 , respectively. The as-prepared composite showed long-term stability and it retains 97% of the initial capacitance after 2000 charge-discharge cycles. The electrochemical impedance spectroscopy (EIS) results confirm the contribution of both ZnAl-LDHs and graphene in the supercapacitor system. The fabricated electrode using the present simple strategy in this report can be further extended to manufacture other electrodes using other composites from the same family for the upcoming energy storage systems. • Composites of ZnAl-LDHs/graphene was synthesized. • ZnAl-LDHs presents vertically aligned 2D sheets. • Graphene sheets are placed near the obtained ZnAl-LDHs. • The obtained electrode exhibited an excellent supercapacitive performances. • The obtained electrodes presented C P ∼ 140 F / g and PD of ∼ 15.359 k W K g − 1 and ED. ∼ 2.016 W h K g − 1

2D α-MoO3-x truncated microplates and microdisks as electroactive materials for highly efficient asymmetric supercapacitors

Two-dimensional truncated microplates and microdisks of molybdenum oxide are synthesized, and their capabilities for superior performance in the charge storage devices are demonstrated. The chemistry of protonated urea with the heptamolybdate [Mo7O24]6− and octamolybdate [Mo8O26]4− ions is innovatively utilized to transform the MoO3-x nanoparticles into truncated microplates and microdisks, without the need of any expensive templates or hydro/solvothermal treatment. The 2D-MoO3-x truncated microplates and microdisks exhibit excellent supercapacitor performance with a high specific capacitance of 410 and 226 F g−1 at a remarkable current density of 20 A g−1. The microstructures also exhibit substantial capacitance retention of > 90% and Coulombic efficiency > 98% for over 12000 continuous charge-discharge cycles, respectively. An asymmetric supercapacitor device of 2D MoO3-x microstructures has been assembled. The device exhibited remarkable energy and power densities of nearly 41 W h kg−1 and 2108 W kg−1 for MoO3-x truncated microplates, and 30 W h kg−1 and 2107 W kg−1 for MoO3-x truncated microdisks, respectively. Our method thus provides a route for facile fabrication of 2D MoO3-x microstructures which can function as excellent charge storage materials even at very high current densities while maintaining their electrochemical stabilities.

Novel MOF-derived 3D hierarchical needlelike array architecture with excellent EMI shielding, thermal insulation and supercapacitor performance

The upcoming 5G era will powerfully promote the development of intelligent society in the future, but it will also bring serious electromagnetic pollution. Thus, the development of efficient, lightweight and multifunctional electromagnetic shielding materials and devices is an important research hotspot around the world. Herein, a novel needlelike Co3O4/C array architecture is constructed from MOF precursor via a simple pyrolysis process, and its microstructure is controllably tailored by changing the pyrolysis temperature. The unique 3D hierarchical structure and multiphase components enable the architecture to provide high-efficiency electromagnetic interference (EMI) shielding, along with good thermal insulation. More importantly, the architecture possesses fast ion transport channels, which can be used to construct supercapacitors with high specific capacitance and excellent cycle stability. Obviously, this work offers a new inspiration for the design and construction of multifunctional electromagnetic materials and devices.

Synthesis of TiC nanotube arrays and their excellent supercapacitor performance

Nanostructured metal carbides have numerous applications in catalysis and energy storage.

One-step and room-temperature fabrication of carbon nanocomposites including Ni nanoparticles for supercapacitor electrodes.

With the increasing importance of power storage devices, demand for the development of supercapacitors possessing both rapid reversible chargeability and high energy density is accelerating. Here we propose a simple process for the room temperature fabrication of pseudocapacitor electrodes consisting of a faradaic redox reaction layer on a metallic electrode with an enhanced surface area. As a model metallic electrode, an Au foil was irradiated with Ar+ ions with a simultaneous supply of C and Ni at room temperature, resulting in fine metallic Ni nanoparticles dispersed in the carbon matrix with local graphitization on the ion-induced roughened Au surface. A carbon layer including fine Ni nanoparticles acted as an excellent faradaic redox reaction layer and the roughened surface contributed to an increase in surface area. The fabricated electrode, which included only 14 μg cm−2 of Ni, showed a stored charge ability three times as large as that of the bulky Ni foil. Thus, it is believed that a carbon layer including Ni nanoparticles fabricated on the charge collective electrode with an ion-irradiation method is promising for the development of supercapacitors from the viewpoints of the reduced use of rare metal and excellent supercapacitor performance.

Exploring supercapacitance of solvothermally synthesized N-rGO sheet: role of N-doping and the insight mechanism.

We demonstrate the method of achieving excellent supercapacitance in nitrogen-doped reduced graphene oxide (N-rGO) sheets by controlling the amount of N-content through the use of different ratios of GO and urea during solvothermal synthesis. Here, urea plays a dual role in reducing GO and simultaneously doping nitrogen into the GO flakes forming exfoliated N-rGO sheets. The nitrogen content in N-rGO samples rises with an increase in the amounts of urea and saturates at a value of ∼14% for the GO : urea ratios beyond 1 : 8. The obtained N-rGO sheets with ∼ 5% N-content (obtained for GO : urea ratio of 1 : 3) were demonstrated as excellent supercapacitor materials. Using a 3-electrode setup, the maximum specific capacitance obtained for this sample was 514 F g-1 at a current density of 0.5 A g-1 (mass normalized current). The insights into the origin of this excellent supercapacitive behavior are explained through our results on optimum N-content, the relative amount of different N-environments, defects/disorders, and the degree of reduction of GO. Importantly, a proper stacking of rGO sheets with moderate N-content (∼5-6%) and a moderate amount of defects is the key to achieve high specific-capacitance. Furthermore, our 2-electrode device demonstrates the excellence of our samples with a Csp of 237 F g-1, a power density of 225 W kg-1, and an energy density of 6.7 W h kg-1 at 0.5 A g-1, exhibiting a high cyclic constancy with high capacitive retention of ∼ 82% even after 8000 cycles. Hence, our work provides a way to control the properties of N-rGO in achieving excellent supercapacitive performance.

Fe-Nx-C Material with Excellent Supercapacitor Performance Prepared Through Oleic Acid Acidification Pretreatment - Oily Sludge Pyrolysis Process

Fe-Nx-C Material with Excellent Supercapacitor Performance Prepared Through Oleic Acid Acidification Pretreatment - Oily Sludge Pyrolysis Process

Screen printing fabricating patterned and customized full paper-based energy storage devices with excellent photothermal, self-healing, high energy density and good electromagnetic shielding performances

• A patterned paper-based energy storage device is fabricated by low-cost screen printing. • The device shows excellent energy storage, photothermal and electromagnetic shielding properties. • The whole paper device with good self-healing performance presents an ultra-high energy density. • White garbage can also be used to prepare high value-added energy storage material. Supercapacitors are favored by researchers because of their high power density, especially with the acceleration of people's life rhythm. However, their energy density, especially from the point of view of the whole energy storage device, is far lower than that of commercial batteries. In this work, a kind of customizable full paper-based supercapacitor device with excellent self-healing ability is fabricated by simple and low-cost screen printing, electropolymerization and dip coating methods. The resultant separator-free supercapacitor device exhibits both ultrahigh gravimetric and areal specific energy (power) densities of 39 Wh kg −1 (69 kW kg −1 ) and 692 μWh cm −2 (236 mW cm −2 ), achieving excellent supercapacitor performance. Notably, the addition of vitrimers endows the whole device with outstanding self-healing properties, which is helpful for enhancing the adaptability of the device to the environment. In addition, this kind of paper-based device also displays good photothermal and electromagnetic shielding performances. These striking features make paper matrix composites attractive in the fields of supercapacitors, medical photothermal treatment and electromagnetic shielding.

Synthesis of amorphous hollow Ni(HCO3)2 nanostructures with excellent supercapacitor performance from nickel-containing electroplating sludge

The complex composition and recycling process of electroplating sludge are the two major obstacles restricting the recycling of metal resources. In this work, Ni(HCO3)2 hollow spheres with unique amorphous structure were prepared via a simple and controllable hydrothermal method using nickel-containing electroplating sludge as raw material and ascorbic acid (AA) as complexing agent. The introduction of AA not only changed the morphology of the sample, but also formed pure phase Ni(HCO3)2. The controllable amorphous structure is beneficial to the diffusion of OH- in the electrolyte. More importantly, its disordered atomic arrangement and metastable structure provide a large number of active sites and ion transmission channels, which improve the specific capacity. Consequently, amorphous Ni(HCO3)2 delivers a large capacitance of 599.8 C g−1 at 1 A g−1, besides large capacitance, it also exhibits large rate capability (61.02% at a current density of 10 A g−1) and cycle performance (capacitance retention 52.09% after 1000 cycles). Importantly, the recoveries of nickel, iron and aluminum are 95.57%, 99.92% and 92.30%, respectively, indicating that electroplating sludge has a good application prospect as electrode materials for supercapacitors.

Selenium-doped carbon nanotubes/nickel selenide coaxial nanocables for energy storage

Coaxial nanocable heterostructures consisting of highly conductive carbon nanomaterial core and active transition-metal compound sheath are promising potential candidates for advanced energy storage materials. Herein, the multi-functional selenium‐doped carbon nanotubes/nickel selenide coaxial nanocables with chemical bonding interface are prepared by using an electroless deposition combined with the following chemical vapor reaction process, in which the nickel layer is first deposited onto the carbon nanotube core and subsequently transformed in-situ into the nickel selenide sheath by the controlled selenization reaction at elevated temperature. Such coaxial structure provides the large active material/electrolyte contact area, and the fast diffusion and transfer of mass and charge in the electrochemical process, thus which endows superior supercapacitive and good lithium storage performances. The coaxial nanocables exhibit a high specific capacity of 340.0 mAh g −1 at 1 A g −1 as an electrode for supercapacitor, and a lithium storage capacity of 600.0 mAh g −1 at 0.1 A g −1 as an anode for lithium-ion batteries. A supercapacitor based on the nanocables delivers a high energy density of 70.0 Wh kg −1 at 803.0 W kg −1 and long cycling stability with 65.0% capacitance retention after 8000 cycles at 10 A g −1 . • Preparing multi-functional Se-CNTs@NiSe nanocables with chemical bonding interface. • Graphene/NiSe nanoribbons are derived due to splitting of coaxial nanocables. • Nanocables show the excellent supercapacitive and lithium storage performances.

Three dimensional hierarchical flower-like CoCuS/Co1-xCuxS electrodes for electrochemical supercapacitors

Recently, the 2021 United nations climate change conference (COP26) have again stressed on the need of carbon neutral economy. To cope up with the power hunger of industrial and/ technological world of hybrid electric vehicles and portable electronic devices it is imperative to search the environment friendly novel materials with property tailoring abilities. In this connection, we have deposited Co1-xCuxS/CoCuS (0.025 ≤ x ≤ 0.1) thin-films via chemical route as an alternative material for supercapacitor application. To asses the suitability of as-deposited thin films, we have characterized thin films using variety of characterization techniques. X-ray photoelectron spectroscopy was used to examine and confirm the chemical states of Co, Cu, and S. Surface morphology of as-deposited CoCuS film (x = 0.075, sample-C3) showed a crumpled flower-like microstructure. Uniform distribution of hillocks and valleys was observed using atomic force microscopy. The topographical outcomes obtained from electrostatic force microscopy and Kelvin probe force microscopy confirmed that the sample-C3 (x = 0.075) is suitable for energy storage applications. Sample-C3 demonstrated excellent supercapacitive performance with a high specific capacitance of 907.55 F g−1 at 5 mV s−1, remarkable rate capability, and ~ 90% of capacitive retention after 5000 cycles in a 1 M KOH electrolyte. Better supercapacitive behavior and cycling stability of the CoCuS samples may offer a perspective for various mixed metal sulfide thin films with hierarchical architectures as an viable alternative for the efficient energy storage devices.

Ion‐exchange synthesis of microporous Co 3 S 4 for enhanced electrochemical energy storage

Replacing oxygen in an oxide-based material with sulfur can produce improved flexibility and more efficient electron transport in its structure leading to enhanced electrical performance. Herein, facile template-free growth of free-standing cobalt (II, III) oxide (Co3O4) on Ni foam via a mild hydrothermal technique followed by its transformation to cobalt (II, III) sulfide (Co3S4) via an ion-exchange is reported. The microstructural morphology, phase, and porosity of the prepared Co3O4 and Co3S4 are characterized by FESEM, XRD, Raman, XPS, TEM, and BET analyses. The electrochemical performance of the Co3S4 film with a microporous morphology is considerably superior to that of Co3O4, exhibiting a high specific capacitance of 1604 F g−1 (905 F g−1 for Co3O4), the excellent restorative ability of ~99% at 1 A g−1 (~96% for Co3O4), and good retention of 98% at 10 A g−1 (~70% for Co3O4). The Co3S4 electrode shows excellent capacitance endurance even after 10 000 charge/discharge cycles and a high energy density of 128.32 Wh kg−1 at 0.72 kW kg−1. A fabricated symmetric Co3S4 supercapacitor device also reveals superior charge/discharge, restorative, and retention performances compared to a Co3O4 one. The excellent supercapacitive performance of phase-transformed Co3S4 electrode is due its large electrochemically active surface area along with synergetic effect of small charge transfer resistance and high relative diffusion coefficient.

Synthesis, Characterization and Evaluation of Supercapacitive Response of Dodecylbenzenesulphonic Acid (DBSA) Doped Polypyrrole/Zirconium Dioxide Composites.

An in-situ chemical oxidative method was used to effectively synthesize a promising supercapacitor material based on PPy/ZrO2 composites. The synthesized materials were characterized by different analytical techniques, such as UV/visible (UV/Vis) spectroscopy, Fourier-transform infra-red spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The inclusion of ZrO2 into the PPy matrix was verified by vibrational spectra and structural analyses. The (TGA) results showed that incorporating ZrO2 into the polymeric matrix improved its thermal stability. In addition, the electrochemical properties of the synthesizedmaterials were investigated byusing cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD). The PPy/ZrO2 composite demonstrated excellent super capacitive performance, and high specific capacity of 337.83 F/g, with an exceedingly high energy density of 187.68 Wh/kg at a power density of 1000 W/kg. The composite materials maintain good stability after 1000 charge and discharge cycles, with 85% capacitance retention. The PPy/ZrO2 possesses a high capacitance, an attractive micro-morphology, and a simple synthesis method. The findings indicate that the PPy/ZrO2 composite could be a promising electrode material for high-performance supercapacitor applications.

Designing NiS/CoS decorated NiCo2S4 nanoflakes towards high performance binder-free supercapacitors

Given their excellent cycling stability, high-power density, and simple structures, supercapacitors have attracted great interest as promising energy storage devices for various systems ranging from small wearable electronic devices to large-scale renewable energy grids. However, it is still a challenge to develop electrodes of supercapacitors with high energy density to meet the requirement of these practical applications. Herein we report a procedure involving electrochemical deposition, hydrothermal conversion, and sulfurization to fabricate a binder-free NiCo2S4@NiS/CoS electrode with excellent supercapacitive performance. The NiCo2S4@NiS/CoS consists of NiCo2S4 nanoflakes, on which CoS and NiS nanoparticles are anchored. Because of the high specific capacitance of NiS and CoS nanoparticles and the good electronic contact between the sulfide components and the conductive substrate, the NiCo2S4@NiS/CoS hybrid material exhibits a high specific capacitance (2551 F g − 1 (354.3 mAh g − 1) at 2 A g − 1), excellent high-rate capability, and good cycling performance. The asymmetric supercapacitor assembled with the NiCo2S4@NiS/CoS cathode and a Fe3O4 nanosheet anode demonstrates high power and energy densities, suggesting that the NiCo2S4@NiS/CoS is suitable for use as the binder-free cathode material of supercapacitors.

One-pot temperature-controlled hydrothermal synthesis of α-MnO2 nanoparticles decorated thermally reduced graphene oxide composite as high-performance flexible aqueous symmetric supercapacitors

In this study, manganese dioxide (MnO2)/thermally reduced graphene oxide (rGO) symmetric supercapacitors were fabricated. The (MnO2/rGO@X) composites with varying reaction temperatures (100, 120, and 140 °C) were prepared from a one-pot hydrothermal approach. First, we optimize the reaction temperature as 120 °C for the MnO2/rGO composite on its electrochemical behaviour in a two-electrode cell. Then, pure MnO2nanoparticles were synthesized at the same reaction temperature. X-ray diffraction (XRD) analysis revealed the presence of α-MnO2 produced through hydrothermal synthesis. The MnO2/rGO composite formation was confirmed by Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The scanning electron microscope (SEM) image of the MnO2/rGO@120 composite showed that the rGO surface was decorated with flakes-like MnO2 nanoparticles. The electrochemical properties of pure MnO2@120 and the MnO2/rGO@120 composite were evaluated using cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge/discharge measurements. In a two-electrode symmetric cell configuration, the MnO2/rGO@120 exhibits a much larger specific capacitance of 413 Fg−1 at a current 1 mA and delivers maximum specific energy 14.3 Wh kg−1 with a specific power of 260 W kg−1. Moreover, the 99.7% efficiency exhibited by this composite symmetric supercapacitor was found to retain after 5000 charge/discharge cycles at 3 mA current. The excellent supercapacitive performance of our MnO2/rGO composite electrode material prepared via one-pot hydrothermal treatment at a reaction temperature of 120 °C has potential applications for energy storage applications.

Rational fabrication of flower-like VS2-decorated Ti3C2 MXene heterojunction nanocomposites for supercapacitance performances

In this work, Ti3C2, was obtained by selective etching of Al in Ti3AlC2 by hydrofluoric and VS2 was modified on two-dimensional Ti3C2 by solvothermal process to prepare VS2/Ti3C2 composites. In the three-electrode system, the prepared VS2/Ti3C2 composites were compared with VS2 and Ti3C2, respectively, and it was found that the electrochemical properties of VS2/Ti3C2 composites were better. The intercalated VS2 nanosheets expanded the distance between Ti3C2 sheets, leading to a wide ion-accessible surface region and fast ionic/electric transport, resulting in the improved the electrochemical performance of the Ti3C2/VS2 composites. Density functional theory (DFT) analysis shows that the prepared VS2/Ti3C2 composite material has high electrical conductivity. Under the current density of 1 A∙g−1, the specific capacity of VS2/Ti3C2 composite is 191.3mAh∙g−1, which is much higher than that of VS2 and Ti3C2. The asymmetric supercapacitors were assembled with VS2/Ti3C2 composites as positive electrodes, and the electrochemical performance was tested when the power density was 1288 W·kg−1 and the energy density was 24 Wh·kg−1. The initial capacity retention is 82.2% after 5000 cycles of constant current charge and discharge at the current density of 2 A·g−1. In short, VS2/Ti3C2 composites show excellent supercapacitor performance in terms of capacity, stability, energy density and power density. It shows that VS2/Ti3C2 is a promising electrode material for supercapacitors.

Quasi-solid, bio-renewable supercapacitor with high specific capacitance and energy density based on rice electrolytes and rice straw-derived carbon dots as novel electrolyte additives

In this work, novel quasi-solid electrolytes and carbon dots as additives were developed for the bio-renewable, high energy-density supercapacitor. The activated carbon from rice straw was used to make an electrode while the carbon dots also from rice straw were combined with rice electrolytes. The supercapacitor using H3PO4/rice electrolyte yielded a specific capacitance, potential window, and energy density of 88 F g−1, 2 V, and 12 Wh kg−1, respectively, at a scan rate of 30 mV s−1. For comparison, electrolyte prepared from conventional H3PO4/poly(vinyl alcohol) yielded only 45 F g−1, 1.6 V, and 4 Wh kg−1. The addition of carbon dots to H3PO4/rice electrolytes further increased the specific capacitance, potential window, and energy density to 144 F g−1, 2.4 V, and 29 Wh kg−1, equivalent to 163%, 120%, and 241% enhancement, respectively. The maximum specific capacitance and energy density reached 491 F g−1 and 98 Wh kg−1, respectively, at a scan rate of 2 mV s−1. The carbon dots improved the supercapacitor performance by simultaneously enhancing the adsorption and diffusion of electroactive species and surface capacitance. Interestingly, the electrode was prepared without the addition of highly conductive carbon and still produced excellent supercapacitor performances. This work thus demonstrates a novel and simple strategy for using a bio-renewable resource for the fabrication of high-performance supercapacitors, which have great practical potential in the field of portable and wearable electronic devices.