Capacitive Performance Research Articles

Synthesis and electrochemical performance of low cost nitrogen-doped carbon cryogel composites as supercapacitor electrodes

Developing cost-effective methods for synthesizing Nitrogen-doped carbon cryogels is crucial for advancing supercapacitor technology due to their enhanced electrochemical properties. Nitrogen-doped porous carbon cryogels are synthesized through the freeze-drying method by substituting resorcinol with phenol and using urea/melamine as nitrogen sources. The effect of nitrogen sources on the structure and electrochemical performance is investigated. In the case of carbon cryogel composites samples, using melamine as the nitrogen source (PMF) is more favorable than using urea (PUF), while both nitrogen-doped samples significantly outperform the undoped samples (PF). The PMF sample displays a specific surface area of 1119.00 m2 g−1, and a nitrogen content of 2.19 wt%. In the three-electrode system, the specific capacitance of the PMF sample reaches up to 247.9 F g−1 at a current density of 0.5 A g−1, and its rate performance is 85.52 %. By comparison, the PF sample exhibits specific capacitance and rate performance of 85.4 F g−1 and 33.44 % under the same parameters. The assembled symmetric supercapacitor in a buckle type system also demonstrates exceptional energy density (14.41 Wh kg−1), long-term cycle stability, and a favorable capacitance retention rate (72.2 %). These excellent electrochemical performances can be attributed to the synergistic effects of the hierarchical pore structures and heteroatoms doping.

Coal-derived boron and phosphorus co-doped activated carbon with expanded interlayer space for high performance sodium ion capacitor anode

Aiming at the key problem of Na+ insertion difficulty and low charge transfer efficiency of activated carbon materials. It is an effective strategy to increase the lattice spacing and defect concentration by doping to reduce the ion diffusion resistance and improve the kinetics. Hence, anthracitic coal is used to prepare activated carbon (AC) and B,P-doped activated carbon (B,P-AC) as the cathode and anode materials for high-performance all-carbon SICs, respectively. AC cathode material has high specific surface area and reasonable micropore structure, which shows excellent capacitance performance. B,P-AC anode material has the advantages of extremely high specific surface area (1856.1 m2/g), expanded interlayer spacing (0.40 nm) and uniform distribution of B and P heteroatoms. Hence, B,P-AC anode achieves a highly reversible Na+ storage capacity of 243 mAh/g at a current density of 0.05 A/g. Density functional theory (DFT) calculations further verify that B,P-AC has stronger Na+ storage performance. The final assembled B,P-AC//AC SIC offers a high energy density of 109.78 Wh kg−1 and a high-power density of 10.03 kW kg−1. The high-performance coal-derived activated carbon of this work provides a variety of options for industrial production of electrode materials for sodium ion capacitors.

New insights into the role of nitrogen doping in microporous carbon on the capacitive charge storage mechanism: From ab initio to machine learning accelerated molecular dynamics

Fundamental understandings of the relationship between ion-electrode interaction and structural feature in porous carbon electrodes at a molecular level provides guidelines for the design of high-performance electric double layer supercapacitors. It is certified by experiments that porous carbon structures doped with nitrogen show enhanced capacitive performance. However, in the theoretical simulations, the fundamental charge storage mechanism is still elusive. In particular, the recent experimental result shows that the generally ignored nitrolic nitrogen (N5) in porous carbon exhibits a positive effect on capacitance, while graphitic nitrogen (N3) does the opposite, which is against with the simulation results based the 2D-modeled porous graphene structure. Here, we perform ab initio molecular dynamics simulations on the N3 and N5-doped carbon/electrolyte interfaces, including both 2D planar and 3D microporous carbon electrodes. Our calculation indicates that N3 in the 3D pore hinders the electrolyte transport, while N5-doped micropore still serves as an electrolyte transport channel through the formation of H-bond. The charge storage mechanism is further elucidated by the analysis of the well equilibrated interfaces obtained from the machine learning force field accelerated molecular dynamics. Our work provides a new insight into the effect of nitrogen doping in 3D porous carbon, which is exactly opposite to the 2D planar graphene. Therefore, we emphasize that differences in the electrochemical conditions of 2D planar and 3D microporous carbon electrodes should be fully considered when analyzing the effects of surface chemistry on charge storage mechanisms.

Chemical reduction-induced defect-rich bismuth oxide-reduced graphene oxide anode for high-performance supercapacitors

We prepare bismuth oxide-reduced graphene oxide (Bi2O3-rGO) composite anode using a one-step chemical precipitation/reduction method. Under a reducing atmosphere, oxygen atoms on the surface of Bi2O3 are gradually removed and neighboring oxygen atoms migrate to the surface, leaving oxygen vacancies. Defective Bi2O3 enhances the number of active sites, providing additional pseudocapacitive performance. The transition metal oxide-based Bi2O3 acts as an anode, providing capacitive performance that far exceeds that of conventional carbon materials. Moreover, the introduction of rGO forms a conductive network for Bi2O3, improving capacitive contribution and ion diffusion capabilities for the electrode. The Bi2O3-rGO-100 (GO added at 100 mg) exhibits a high specific capacitance of 1053F/g at 1 A/g, significantly higher than that of Bi2O3 (866F/g). The Bi2O3-rGO-100 anode and Ni3Co2-rGO cathode are assembled into a battery-type supercapacitor. The coin-cell device achieves an energy density of 88.2 Wh kg−1 at a power density of 850 W kg−1. The Ni3Co2-rGO//Bi2O3-rGO-100 pouch-cell device demonstrates an extremely low Rct of 0.77 Ω. At a power density of 850 W kg−1, the energy density reaches 118.5 Wh kg−1, and remains 67.4 Wh kg−1 at 8500 W kg−1.

Modification of hydrochar derived from palm waste with thiourea to produce N, S co-doped activated carbon for supercapacitor

This study examines modifying hydrochar from biomass to produce N, S codoped activated carbon for supercapacitor applications. Hydrochar was created from oil palm empty fruits bunch with the activating agent CaCl2 at 275 °C for 60 minutes. Hydrochar modification was carried out by the impregnation method in thiourea solution for 2 hours and impregnation ratio (1, 2, and 3) and continued the activation process at 800 °C for 120 minutes. The in-depth exploration of porosity unveiled a distinct pattern, as the progressive increase in impregnation ratio exerted a corresponding dampening effect on the activated carbon's surface area (151.57−234.56 m2 g−1). Subsequent engagement in electrochemical scrutiny, facilitated by a meticulously designed two-electrode system, revealed a pinnacle in capacitance performance, culminating at an impressive 135.12 F g−1at 0.5 A g−1 The energy and power densities achieved remarkable magnitudes in concert, scaling up to 3.4 Wh kg−1 and 202.6 W kg−1, respectively. Demonstrating robustness through the crucible of a 5000-cycle durability evaluation, the modified activated carbon-based supercapacitor emerged with unswerving capacitance retention and coulombic efficiency, each clocking in at a steadfast 106 % and 95 %. The discerning insights drawn from this inquiry underscore that the strategic incorporation of N, S-modification via thiourea engenders a qualitative enhancement within the supercapacitor's performance domain.

Synthesis of CuO/NiO nanostructured hybrid electrode for supercapacitors

Supercapacitors employing copper metal oxides have garnered significant interest due to their substantial theoretical capacity and expansive active surface area. However, the performance of pure copper oxide electrode materials cannot meet the high demands currently placed on supercapacitors. In this study, a convenient, efficient, two-step electrodeposition method was utilized to develop micro/nanostructures of CuO/NiO on nickel foam. The synthetic strategy optimizes the capacitive performance of the composite by adjusting the deposition parameters during the growth of the NiO film.The CuO/NiO electrode can provide an area ratio capacitance of up to 1435.62 mF/cm2, the addition of NiO improves the area capacitance of the electrode material and the capacitance retention after cycling. In addition, the CuO/NiO composite material has been used to prepare solid-state symmetric supercapacitors, the device can reach a maximum energy and power density of 31.89 μWh/cm2 and 2099.76 μW/cm2, respectively. These results suggest that CuO/NiO electrodes exhibit promising potential as energy storage electrode materials.

Potential Development of Porous Carbon Composites Generated from the Biomass for Energy Storage Applications.

Creating an innovative and environmentally friendly energy storage system is of vital importance due to the growing number of environmental problems and the fast exhaustion of fossil fuels. Energy storage using porous carbon composites generated from biomass has attracted a lot of attention in the research community. This is primarily due to the environmentally friendly nature, abundant availability in nature, accessibility, affordability, and long-term viability of macro/meso/microporous carbon sourced from a variety of biological materials. Extensive information on the design and the building of an energy storage device that uses supercapacitors was a part of this research. This study examines both porous carbon electrodes (ranging from 44 to 1050 F/g) and biomasses with a large surface area (between 215 and 3532 m2/g). Supposedly, these electrodes have a capacitive retention performance of about 99.7 percent after 1000 cycles. The energy density of symmetric supercapacitors is also considered, with values between 5.1 and 138.4 Wh/kg. In this review, we look at the basic structures of biomass and how they affect porous carbon synthesis. It also discusses the effects of different structured porous carbon materials on electrochemical performance and analyzes them. In recent developments, significant steps have been made across various fields including fuel cells, carbon capture, and the utilization of biomass-derived carbonaceous nanoparticles. Notably, our study delves into the innovative energy conversion and storage potentials inherent in these materials. This comprehensive investigation seeks to lay the foundation for forthcoming energy storage research endeavors by delineating the current advancements and anticipating potential challenges in fabricating porous carbon composites sourced from biomass.

Improved Energy Density at High Temperatures of FPE Dielectrics by Extreme Low Loading of CQDs.

Electrostatic capacitors, with the advantages of high-power density, fast charging-discharging, and outstanding cyclic stability, have become important energy storage devices for modern power electronics. However, the insulation performance of the dielectrics in capacitors will significantly deteriorate under the conditions of high temperatures and electric fields, resulting in limited capacitive performance. In this paper, we report a method to improve the high-temperature energy storage performance of a polymer dielectric for capacitors by incorporating an extremely low loading of 0.5 wt% carbon quantum dots (CQDs) into a fluorene polyester (FPE) polymer. CQDs possess a high electron affinity energy, enabling them to capture migrating carriers and exhibit a unique Coulomb-blocking effect to scatter electrons, thereby restricting electron migration. As a result, the breakdown strength and energy storage properties of the CQD/FPE nanocomposites are significantly enhanced. For instance, the energy density of 0.5 wt% CQD/FPE nanocomposites at room temperature, with an efficiency (η) exceeding 90%, reached 9.6 J/cm3. At the discharge energy density of 0.5 wt%, the CQD/FPE nanocomposites remained at 4.53 J/cm3 with an efficiency (η) exceeding 90% at 150 °C, which surpasses lots of reported results.

Facile metal-oriented in-situ growth of zeolitic imidazole framework membranes on carbon fiber cloth with superior capacitive performance

Facile metal-oriented in-situ growth of zeolitic imidazole framework membranes on carbon fiber cloth with superior capacitive performance

Engineering surface electronic of MXene to boost pseudocapacitive behavior

Despite exhibiting impressive capacitance performance in acidic electrolytes, MXene electrodes surfer from poor electrochemical performance in neutral electrolytes. Consequently, improving the capacitance performance of MXene electrodes within neutral electrolytes is imperative for their advancement in energy storage applications. Herein, an alloying strategy was employed to incorporate the V element into the M−site of Ti3C2 MXene. Theoretical calculations reveal that the incorporation of V atoms enhances the electronic conductivity, enlarges the work function, and improves the chemical affinity and adsorption capacity of MXene towards electrolyte ions, which are conducive to improving the capacitance performance of MXene. The as-synthesized V0.2Ti2.8C2 MXene electrode exhibits good capacitance performance and demonstrates good electrochemical stability with a specific capacitance retention as high as 86% after 10,000 charging/discharging cycles at 10 A/g. This work provides a universal strategy for developing high-performance MXene electrodes in neutral electrolyte.

Hydrothermal synthesis of Ni, Co hydroxide nanosheet array on vertically suspended carbon cloth for flexible high-performance supercapacitors

The investigation of Ni(OH)2 electrode materials has been a prominent issue in the field of electrochemical energy. The slow ion diffusion kinetics and inherent low electronic conductivity of Ni(OH)2 restrict its electrochemical performance and application in practice. In this work, mixed-phase nickel-cobalt layered double hydroxide (NiCoLDH) array structures are successfully grown directly on vertically suspended carbon cloth (CC). In contrast to the traditional hydrothermal method, the vertically suspended carbon cloth affordes adequate reaction sites to ensure optimum array structure growth. This unique structure realizes a large mass loading of the active material. Meanwhile, the introduction of flexible electrode substrate carbon cloth effectively enhances the mechanical properties of the electrode. Due to the powerful electrochemistry kinetics, NiCoLDH/CC-1.5 exhibites a great capacitive and excellent rate performance of 1516.5 F g−1 at 1 A g−1 and 1073.75 F g−1 even at 20 A g−1. The assembled asymmetric supercapacitor demonstrates a favorable cycling stability (capacitance retention of 90.11 % after 10,000 cycles at 5 A g−1).

Enhancing capacitive performance of MoS2 through Fe doping: Synthesis, characterization, and electrochemical evaluation for supercapacitor applications

The capacitive performance of bare MoS2 is limited due to its poor electronic conductivity. Therefore, we tried to dope different weight percentages (2 %, 4 %, 6 %, 8 %, and 10 %) of Iron (Fe) into the MoS2 to promote more active sites to improve its energy storage capacity. Given this, we have synthesized bare MoS2 and Fe-doped MoS2 using the hydrothermal method for electrochemical charge storage application. The effect of doping was well assessed using different physicochemical tests. The electrochemical properties of the bare MoS2 and Fe-doped MoS2 were evaluated using a three-electrode setup in a 3 M KOH aqueous electrolyte. As a result, the 8 % Fe-doped MoS2 electrode material demonstrates the maximum specific capacitance (CSP) of 545 F/g @ 1 A/g with 84.8 % capacitive retention over 2000 cycles at 5 A/g. Additionally, we fabricated an asymmetric solid-state supercapacitor device, which reveals a high CSP of 74.28 F/g at 4 A/g with an energy density of 72.79 Wh/kg and a power density of 10.07 kW/kg. The results asserted that the Fe-doped MoS2 is a potential electrode material for supercapacitor application.

Instantaneous reduction of inkjet-printed graphene oxide on PVDF nanofibers for high-performance ultralight flexible supercapacitors

As the demand for innovative electronic devices continues to grow, flexible electronic products which offer a solution capable of adapting to various shapes and deformations, are increasingly gaining prominence. This study innovatively uses electrospun polyvinylidene fluoride (PVDF) nanofibers as substrates and employs reactive inkjet printing (RIP) technology to deposit and instantaneously reduce graphene oxide (GO), fabricating ultralight flexible all-solid-state supercapacitors. To verify that PVDF nanofibers as substrates can facilitate the uniform deposition of GO ink during inkjet printing and prevent the dispersion of GO into the internal structure, thereby achieving good capacitive performance with the fewest layers of printing, this study analyzes and compares the capacitive performance differences among 1rGO/PVDF, 3rGO/PVDF, and 5rGO/PVDF samples. The results have been confirmed that the GO ink was effectively instantaneously in-situ reduced by l-ascorbic acid (AA) to rGO by RIP system, and the specific capacitance of 1rGO/PVDF electrode was founded of 83.29 F/g at a current density of 2 A/g from the GCD analysis with a corresponding energy density of 7.5 Wh kg−1 and power density of 1.04 kW kg−1. The 1rGO/PVDF supercapacitor exhibits excellent electrochemical stability, maintaining 93 % efficiency after 4000 charge-discharge cycles at a current density of 2 A/g.

Interfacially Ordered NiCoMoS Nanosheets Arrays on Hierarchical Ti3C2Tx MXene for High-Energy-Density Fiber-Shaped Supercapacitors with Accelerated Pseudocapacitive Kinetics.

Balancing electrochemical activity and structural reversibility of fibrous electrodes with accelerated Faradaic charge transfer kinetics and pseudocapacitive storage are highly crucial for fiber-shaped supercapacitors (FSCs). Herein, we report novel core-shell hierarchical fibers for high-performance FSCs, in which the ordered NiCoMoS nanosheets arrays are chemically anchored on Ti3C2Tx fibers. Beneficial from architecting stable polymetallic sulfide arrays and conductive networks, the NiCoMoS-Ti3C2Tx fiber maintains fast charge transfer, low diffusion and OH- adsorption barrier, and stabilized multi-electronic reaction kinetics of polymetallic sulfide. Consequently, the NiCoMoS-Ti3C2Tx fiber exhibits a large volumetric capacitance (2472.3 F cm-3) and reversible cycling performance (20,000 cycles). In addition, the solid-state symmetric FSCs deliver a high energy density of 50.6 mWh cm-3 and bending stability, which can significantly power electronic devices and offer sensitive detection for dopamine.

PEDOT-Doped Mesoporous Nanocarbon Electrodes for High Capacitive Aqueous Symmetric Supercapacitors.

Poly(3,4-ethylenedioxythiophene) (PEDOT) and PEDOT-functionalized carbon nanoparticles (f-CNPs) were synthesized by in situ chemical oxidative polymerization and pyrolysis methods. f-CNP-PEDOT nanocomposites were prepared by varying the concentration of PEDOT from 1 to 20% by weight (i.e., 1, 2.5, 5, 10, and 20 wt%). Several characterization techniques, such as field-emission scanning electron microscopy (FESEM), attenuated total reflectance-Fourier transform infrared (ATR-FTIR), X-ray diffraction (XRD), N2 Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) analyses, as well as cyclic voltammetry (CV), galvanostatic charge discharge (GCD), and electrochemical impedance spectroscopy (EIS), were applied to investigate the morphology, the crystalline structure, the N2 adsorption/desorption capability, as well as the electrochemical properties of these new synthesized nanocomposite materials. FESEM analysis showed that these nanocomposites have defined porous structures, and BET surface area analysis showed that the standalone f-CNP exhibited the largest surface area of 801.6 m2/g, whereas the f-CNP-PEDOT with 20 wt% exhibited the smallest surface area of 116 m2/g. The BJH method showed that the nanocomposites were predominantly mesoporous. CV, GCD, and EIS measurements showed that f-CNP functionalized with 5 wt% PEDOT had a higher capacitive performance compared to the individual f-CNPs and PEDOT constituents, exhibiting an extraordinary specific capacitance of 258.7 F/g, at a current density of 0.25 A/g, due to the combined advantage of enhanced electrochemical activity induced by PEDOT doping, and highly developed porosity of f-CNPs. Symmetric aqueous supercapacitor devices were fabricated using the optimized f-CNP-PEDOT doped with 5 wt% of PEDOT as active material, exhibiting a high capacitance of 96.7 F/g at 1.4 V, holding practically their full charge, after 10,000 charge-discharge cycles at 2 A/g, thus providing the highest electrical electrodes performance. Hereafter, this work paves the way for the potential use of f-CNP-PEDOT nanocomposites in the development of high-energy-density supercapacitors.

Enhancing the electrochemical properties of biopolymer composites using starch‐graphene nanoplatelets

AbstractThe study presents the ideal distribution of graphene nanoplatelets (GNP) within the thermoplastic starch (TPS) matrix significantly elevated the thermal and electrical conductivities, as well as the electrochemical efficiency of the biocomposites. Additionally, the incorporation of GNP resulted in an increased thermal stability for the TPS, as indicated by the elevated temperatures required for maximum degradation. The biocomposites exhibited a self‐aligned layered structure, creating conductive pathways and enhancing electron conduction. An electrical conductivity increased as the concentration of GNP increased, with the highest conductivity observed on the top and bottom surface with the value of 4.23 × 10−7 S/m and 3.92 × 10−6 S/m when 12 wt% of GNP was added. The presence of hydroxyl groups in TPS facilitated the formation of hydrogen bonds with GNP, preventing GNP from stacking and forming a more uniform conductive network within the film. The addition of 15 wt% GNP also improved the capacitive performance of the TPS matrix, as evidenced by higher current responses and larger quasi‐rectangular areas in the cyclic voltammetry curves compared to neat TPS. The Nyquist plots which are illustrated impedance data showed that the TPS film with 12 wt% GNP exhibits the smallest semicircle, indicating the highest conductivity which is suggested that GNP improves charge transfer compared to pure TPS.Highlights Optimal dispersion of GNP enhanced the biocomposite's properties. The electrical conductivity increases with the GNP content until 12 wt%. TPS/GNP self‐aligned layered improved conduction and capacitive behavior. GNP improved thermal stability by restricting polymer chain movement. Electrochemical impedance shows improved properties of TPS/GNP.

Plasma Engineering of Co4N/CoN Heterostructure for Boosting Supercapacitor Performance.

Supercapacitor electrode materials play a decisive role in charge storage and significantly affect the cost and capacitive performance of the final device. Engineering of the heterostructure of metal-organic framework (MOF)-derived transition metal nitrides (TMNs) can be conducive to excellent electrochemical performance owing to the synergistic effect, optimized charge transport/mass transfer properties, and high electrical conductivity. In this study, a Co4N/CoN heterostructure was incorporated into a nitrogen-doped support by radio-frequency (RF) plasma after simple pyrolysis of Co-based formate frameworks (Co-MFFs), with the framework structure well retained. Plasma engineering can effectively increase the ratio of Co4N in the Co4N/CoN heterostructure, accelerating the electron transfer rate and resulting in a rough surface due to the reduction effect of high-energy electrons and the etching effect of ions. Benefiting from the plasma modification, the obtained electrode material Co4N/CoN@C-P exhibits a high specific capacitance of 346.2 F·g-1 at a current density of 1 A·g-1, approximately 1.7 times that of CoN/Co4N@C prepared by pyrolysis. The specific capacitance of Co4N/CoN@C-P reaches 335.6 F·g-1 at 10 A·g-1, approximately 96.9% of that at 1 A·g-1, indicating remarkable rate capability. Additionally, the capacitance retention remains at 100% even after 1000 cycles, suggesting excellent cycling stability. The rational design and plasma engineering of the TMN heterostructures at the nanoscale are responsible for the excellent electrochemical performance of this novel composite material.

Machine learning modeling of the capacitive performance of N-doped porous biochar electrodes with experimental verification

N-doped porous biochar is considered as a promising carbon material for supercapacitor electrodes application. However, the intrinsic relations and effect mechanisms of the pore structure and N-doping to the capacitive performance are still inscrutable, giving rise to the challenges for enhancing the capacitive performance by regulating the physicochemical properties of N-doped biochar. In this study, various machine learning models were established to predict the specific capacitance of N-doped biochar electrodes based on the pore structure and N-doping properties. The effect mechanisms of pore structure and N-doping to the specific capacitance were also explored. Results showed that Random Forest model predicted the specific capacitance most accurately. The generalization performance of the model was verified to be quite well with our experiments. It is suggested that developing pore structure with abundant micropores plays more important role than N-doping in enhancing the specific capacitance. The optimal interval of each physiochemical property of N-doped biochar were also determined to maximize the specific capacitance. Furthermore, synergistic effects of pore structure and N-doping to the specific capacitance were revealed. This study provides a useful guideline for N-doped porous biochar production with the aim of capacitive performance enhancement.

One single-atom Mn doping strategy enabling two functions of oxygen reduction reaction and pseudocapacitive performance

Single-atom metal species as highly effective active sites are crucial for enhancing energy storage and conversion properties. However, achieving the simultaneous construction of single-atom sites and the regulation of matrix structures to enable their application in both energy storage and conversion remains a challenge. Here, we have successfully developed unique MnN2C2 active sites, atomically dispersed on N-doped mesoporous graphitic carbon sheets (MnSAs/NMC). This is accomplished through the strategic utilization of MnCl2 salt, which serves dual roles of a pore-forming agent and a template. The MnSAs/NMC catalyst demonstrates compelling electrocatalytic activity for the oxygen reduction reaction (ORR), with an impressive half-wave potential (E1/2 = 0.90 V), alongside superior capacitance reaching 444 F g-1 at 0.5 A g-1 for supercapacitors. Crucially, both experimental and theoretical simulations validate that the single-atom dispersed MnN2C2 optimizes the adsorption energy of reactants and intermediates in the ORR process and pseudocapacitive behavior, leading to excellent ORR activity and capacitive performance. Interestingly, MnSAs/NMC-based Zn-air batteries exhibit concurrently high-power density derived from capacitive property and high energy density enhanced by ORR process. This study presents a novel preparation method for single-atom catalysts, which paves the way for the commercial application of super energy storage and conversion devices.

CO2-regulated, ultrahigh-concentration aqueous electrolytes for high energy and power of supercapacitors

Aqueous supercapacitors are recognized for their high power density, ultralong cycle life, and reliable safety. However, their widespread applications are impeded by low energy density arising from the narrow electrochemical stability windows of aqueous electrolytes. Although the use of high-concentration aqueous electrolytes can mitigate this issue, sluggish ion diffusion within these electrolytes results in decreased capacitance and power performance of supercapacitors. Herein, we propose the simultaneous achievement of high energy and power density of supercapacitors using carbon dioxide (CO2)-regulated high-concentration aqueous electrolytes. The introduction of CO2 enables greater capacitance in sodium perchlorate (NaClO4)-containing electrolyte than sodium nitrate (NaNO3)- and sodium bis (fluorosulfonyl)imide (NaFSI)-containing electrolytes. This is attributed to the increased H+ concentration and the unique interaction between CO2 and ClO4−, leading to a denser counter-ion arrangement on the electrode surface. Notably, the CO2-regulation strategy is effective in a nearly-saturated 17 mol kg−1 NaClO4 electrolyte, showing an increase in energy density of up to 27.8 %, while maintaining a high 2.2 V operating voltage and a long >20 000 cycle life of supercapacitors. This study offers a distinct insight into the regulation of high-concentration aqueous electrolytes for comprehensive enhancement of supercapacitor performance.