Redox Additives Research Articles

A crucial investigation on the N, S dual-doped rGO for the electrochemical detection of mutilfarious analytes and energy storage behaviour in dual redox additives

The dual application-based scenario in electrochemistry has gained substantial reliability and benefits across various domains. In this study, N, S dual-doped graphene (NSGO) was synthesized via hydrothermal method and utilized for supercapacitor and electrochemical sensing applications. For electrochemical sensing, the NSGO-modified glassy carbon electrode (NSGO/GCE) was used to detect 2,4-dinitrophenol (DNP), 2,4-dinitrotoluene (DNT), hydroquinone (HQ) and resorcinol (RC). The NSGO/GCE demonstrated enhanced sensing performance with low detection limits of 16 nM (DNP), 12 nM (DNT), 0.1 µM (HQ) and 0.08 µM (RC) in a linear dynamic range from 0.1 µM to 60.0 µM (DNP, DNT) and 1.0 µM to 500.0 µM (HQ, RC). The NSGO/GCE sensor exhibited excellent reproducibility and stability, with its practical utility validated through real water sample testing. In supercapacitor applications, the NSGO electrode achieved an impressive gravimetric capacitance of 373 F g-1 in 1 M H2SO4 solution at 0.5 A g-1. Symmetric supercapacitor analyses demonstrated that the NSGO cell in 0.01 M KI-0.01 HQ/1 M H2SO4 achieved an enhanced energy density of 65 Wh Kg-1 at 4 A g-1, which is three times superior to 0.01 M HQ/1 M H2SO4 (21.7 Wh Kg-1).

Sustainable graphitic carbon derived from oil palm frond biomass for supercapacitor application: Effect of redox additive and artificial neural network‑based modeling approach

One-step pyrolyzed graphitic carbon (GC) derived from oil palm frond biomass was synthesized at different durations (1, 3, and 5 h) without utilizing of activating agent. The optimum GC-5 h exhibited a honeycomb-like structure (1.9 nm), high carbon content (84 %), graphitic peak at 2θ ∼ 24.2°, and wide pore size (2.17 nm) suitable to accommodate solvated electrolyte ions. Symmetric supercapacitor (SSC) cells with three redox additives (hydroquinone (HQ), ammonium monovanadate (AM), and potassium ferrocyanide (PF)) in H2SO4 electrolyte are tested. The GC-5 h SSC shows a CS of 595F/g in 0.01 M HQ/H2SO4 electrolyte at a current density of 3 A/g. The cell exhibits an energy density (ED) of 22 Wh kg−1 and a power density (PD) of 2,400 W kg−1. It demonstrates a capacitance retention of 93 % after 10,000 cycles. To develop the intricate interactions between the electrode structure, active operating circumstances, and electrochemical performance of the SSC, an artificial neural network (ANN) approach was applied herein. The model uses the Levenberg-Marquart training method, incorporating the Tanh and Purelin activation functions. The data demonstrate that the constructed ANN model can predict the SSC with values that nearly match the experimental data with an MSE of 6.8122 × 10−5 and R of 0.9989.

Carbon Decorated MOF for Low-Cost Aqueous Al-Ion Supercapacitors: Effect of Redox Additives

The performance enhancement of ZIF-67 based Al-ion supercapacitors using conductive additives is presented. By using the simple co-precipitation technique, the porous ZIF-67 and composites of ZIF-67 with two distinct forms of carbon rGO and CNS were synthesized. Physiochemical characterizations like XRD, BET, FTIR, etc., were performed to confirm the successful synthesis of ZIF-67 and its composites. The electrochemical measurements were performed in the three-electrode configuration using 0.5 M AlCl3 electrolyte. Out of all, the composite of ZIF-67 with rGO (ZIF-67_rGO) outperformed all other materials because of its larger specific surface area and enhanced electrical conductivity. Further, the electrolyte modification was performed in 6 mM KFCN as a redox additive for ZIF-67_rGO composite. Here, the specific capacitance of ZIF-67_rGO composite enhanced from 245 F g-1 to 346 Fg-1 at 1 A g−1 current density. Using the redox additive, we observe an increment of almost 41% in ZIF-67_rGO composite than its pristine counterpart. The composite also delivered good cycling stability with excellent coulombic efficiency of 89% and 95% after 1000 cycles, at 5 A g-1 current density, respectively.

Defect-rich carbon nanosheets promoting power density of lithium-ion capacitors in redox electrolyte system

The introduction of redox additives, for example lithium iodide into the catholyte of lithium-ion capacitors can achieve capacity matching between the cathode and anode through the additional capacity provided by the redox reaction. However, the relatively slow redox reaction rate exacerbates the issue of kinetic imbalance between the cathode and anode during charging and discharging process, resulting in reduced coulombic efficiency and power density of lithium-ion capacitors. Herein, we doped carbon nanosheets with NH3 followed by high temperature treatment to obtain carbon nanosheets with rich defects. Theoretical calculations show that defect sites have a mild adsorption effect on iodide. Moreover, the electrochemical evaluation reveals that the defect structure can promote the redox reaction kinetics, thus increasing the electrochemical performance, especially power density of lithium-ion capacitors in the redox electrolyte system.

Unveiling the Supercapacitive Performance of B, P Dual‐Doped Graphene in Triple Redox Additives

AbstractDual heteroatom doping of graphene is currently presumed as more promising for energy storage applications. In addition, the development of energy density with multiple redox additives is paying special attention. Here, we report the fabrication of B, P dual‐doped graphene in three various weight combinations. The formation and the quantity of the prepared samples were investigated by XRD, FT‐IR, EDAX and XPS. The B, P dual‐doped graphene derived from the weight ratio of boron and phosphorus dopant in 1 : 3 has achieved an enriched gravimetric capacitance of 360 F g−1 at 1 A g−1 (1 M H2SO4) and greater than RGO (151 F g−1). The energy density of the fabricated symmetric supercapacitor cell is found to be 50 Wh kg−1 in triple redox additives in 1 M H2SO4 solution which is greater than KI (33 Wh Kg−1) and 1 M H2SO4 alone (5 Wh Kg−1) at 2 A g−1. Also, the same cell delivered an increased stability of 99.7 % of capacitance retained from its initial value after 7000 charge–discharge cycles at 5 A g−1.

Metal-Organic Framework for Aluminum based Energy Storage Devices: Utilizing Redox Additives for Significant Performance Enhancement.

There are various methods being tried to address the sluggish kinetics observed in Al-ion batteries (AIBs). They mostly deal with morphology tuning, but have led to limited improvement. A new approach is proposed to overcome this limitation. It focuses on the use of a redox additive modified electrolyte in combination with framework like materials, which have wider channels. The ordered microporous and interconnected framework of ZIF 67, with large surface area, effectively facilitates the diffusion of aluminum ions. Therefore, AIBs are able to exhibit a superior discharge capacity of 288 mAh g-1 at 0.2 A g-1 current density with robust cycling stability. The addition of potassium ferricyanide as a redox-active species in an aqueous solution of aluminum chloride (supporting electrolyte) leads to significant enhancement in the specific capacity with much higher cycling stability. Al-ion based BatCap devices can be assembled by using ZIF 67 as the cathode, ZIF 67 derived porous carbon as the anode, and a redox additive modified electrolyte. The BatCap device exhibits excellent energy density of 86 Wh kg-1 at a power density of 2 KW kg-1, which is higher than reported aqueous AIBs. The ex situ characterization clearly explains the unexplored mechanism of redox additives in AIBs.

Reducing the environmental impact of lithium-ion battery recycling through co-processing of NCM and LFP

Due to its potential environmental hazards and the importance of valuable metal supply, the recycling of spent lithium-ion batteries (LIBs) has attracted widespread attention. The hydrometallurgical process for recycling spent lithium-ion batteries faces the problem of excessive acid consumption and the need for different redox additives to improve the leaching rate of major metals which will result in issues such as resource waste and secondary pollution. In this study, using LFP and NCM as raw materials, the inherent oxidation/reduction characteristics between them were utilized to achieve leaching rates of over 99 % for Ni, Mn, Li, and over 95 % for Co, without the addition of any redox additives under near stoichiometric sulfuric acid. The leaching kinetics and reaction mechanism of different metals indicate that LFP rapidly dissolves in the sulfuric acid solution, with the released Fe2+ acting as a reducing agent. The subsequent slower reaction between Fe2+ and NCM becomes the rate-controlling step. Afterwards, the leachate regulated by solution control can be further used to prepare Ni-Co-Mn hydroxide precursors and lithium carbonate after the formation of FePO4. This method effectively reduces chemical consumption, mitigates environmental footprint, and achieves highly economical recovery of metals from spent lithium-ion batteries.

High-performance flexible planner device featuring WS2 electrode and non-aqueous polymeric ionic electrolytes incorporated with ionic liquid and dual redox additives

Introducing redox-active species to enhance redox-activity at electrode–electrolyte interfaces, and designing the rational architecture of flexible supercapacitors comprising high-performance active materials and electrolytes with a wide potential window would be a key strategy to boost energy and power density. Herein, for the first time, we prepared an ionic liquid-based polymer electrolyte (IL/PE) by entrapping ionic liquid N-methyl-N-butyl pyrrolidinium bis (trifluoromethane sulfonyl) imide (P14TFSI)) in a polymer electrolyte Poly (diallyl dimethylammonium bis (trifluoromethane sulfonyl) imide (PDADMATFSI)) and blended with dual redox-additives (potassium iodide, KI and diphenylamine, DPA). The IL/PE with dual redox additives, demonstrates spectacular flexibility, high ionic conductivity (∼23.8 × 10−4 S cm−1), and stability in a wide potential window (∼5.9 V). A symmetrical interdigitated planner device is fabricated using dual redox-active IL/PE and flower-like WS2 electrode material. Benefiting from the synergistic effect of dual redox-active additive, the highest energy density of 47.86 µWh cm−2 at a power density of 3509 µW cm−2, and a high working potential (3 V) with excellent cycling stability upto 20,000 cycles has been achieved.

Mixed metal oxide-based binder-free electrode and redox additive electrolyte combination for enhanced supercapacitor performance

In this study, a novel Co3O4/CeO2 nanocomposite for supercapacitors was fabricated through a one-step hydrothermal method, to achieve distinct crystalline phases and a unique flower-like structure. Integrated into a binder-free electrode (BFE) on Ni foam, the Co3O4/CeO2@NF electrode outperformed individual Co3O4 and CeO2-based electrodes. The synergistic effect between Co3O4 and CeO2, enhances the overall surface area, porosity and conductivity of the composites, which improved the supercapacitor characteristics. Detailed analyses confirmed the Co3O4/CeO2@NF electrode's superior cyclic voltammetry, galvanostatic charge-discharge, rate capability, and stability under potassium hydroxide (KOH) and redox additive electrolytes (RAE). The incorporation of RAE further boosted the performance, showcasing the potential for advanced energy storage applications. The assembled asymmetric supercapacitor (ASC) device exhibited outstanding energy and power densities, making it promising for practical applications. Comprehensive electrochemical impedance spectroscopy (EIS) studies offered insights into charge transfer dynamics, highlighted the positive impact of redox additives. This work contributed to understand the synergistic effects in metal oxide composites on advancing the high-performance supercapacitor development.

Activated 2D biocarbon nanosheets from kapok fiber as an electrode material for supercapacitor with high energy density in redox electrolyte

Water-based biocarbon as an electrode material of supercapacitor for energy storage equipment has been widely studied because of its simple preparation, low cost, environmental friendliness and good cycle stability, but its low specific capacitance and energy density are the keys to hinder its development. In this study, 2D biocarbon nanosheets from kapok fibers were prepared via KOH activation. ACKF-2, an as-prepared activated biocarbon with an alkali-carbon mass ratio of 5:1, had a very high specific surface area of 3359.2 m2/g and a high pore volume of 2.1415 m3/g. Thus, ACKF-2 exhibits a high specific capacitance of 405 F/g at a current density of 1 A/g in a 6 mol/L KOH electrolyte. To further improve the electrochemical performance of ACKF-2, two redox additives, K3Fe(CN)6 and K4Fe(CN)6, were chosen as novel redox electrolytes. At a current density of 10 A/g, ACKF-2 showed a superhigh specific capacitance of 3380 F/g in the 1 mol/L H2SO4 electrolyte with adding K3Fe(CN)6 and K4Fe(CN)6. A symmetrical-supercapacitor device consisting of ACKF-2 and the new-type redox electrolyte can achieve an extremely high energy density of 264.1 Wh/kg at a high power density of 4593 W/kg. Therefore, this study provides a new energy storage scheme that can greatly improve the water-based carbon supercapacitor.

Unveiling the potential of redox electrolyte additives in enhancing interfacial stability for Zn-ion hybrid capacitors

Zinc-ion hybrid capacitors (ZICs) that combine the characteristics of metal-ion batteries and supercapacitors are emerging to fulfill high energy-power demands. The objective of this study is to address the challenges in the practical implementation of metallic zinc for ZICs. In this work, we explore redox molecules based on anthraquinone compounds as electrolyte additives for the interfacial engineering of Zn anodes. The results reveal that the additives enable favorable solvation of Zn2+ through metal ion-ligand coordination. The redox additives improve the lifespan of Zn//Zn cells from 50 to 1600 cycles at 2 mA cm−2 and 1 mAh cm−2 due to the suppression of parasitic reactions and the mitigation of by-product formations. The redox properties of additives strengthen the pseudocapacitive behavior of the ZICs, enabling efficient interfacial charge and mass transfer. The redox-enhanced device manifests an increased capacity of 195.0 mAh g − 1 with improved cycling stability, compared to that of 149.6 mAh g − 1 for the additive-free electrolyte. The universal strategy, based on the synergistic effects of redox additives, is demonstrated by a collection of molecules with similar structures. This work unveils a conceptually new approach that utilizes redox additives to formulate advanced electrolytes for aqueous energy storage.

Redox additive effects on the electrochemical performance of hydrothermally grown, binder-free CuO nanosheets in aqueous electrolytes

Adding redox additives into the traditional electrolytes is an efficient approach to achieving high-performance binary metal oxide electrode-based supercapacitors (SCs). Herein, binder-free CuO nanosheets are developed on nickel foams via a facile hydrothermal approach, and their charge storage performance in K3[Fe(CN)6] (KFCN) redox additive electrolyte is investigated. In a three-terminal (3T) configuration, the as-prepared electrode demonstrates a remarkable capacitance of 2755 mF cm−2 (2296 F g−1) in KFCN redox additive electrolyte, which is 10 times greater than that obtained in bare KOH electrolyte (266 mF cm−2 or 222 F g−1). Further, the 93 % capacitance retention after 2000 cyclic voltammetry cycles confirms the reasonable stability of the CuO electrode for SCs with redox additives electrolyte. Additionally, the assembled CuO electrodes-based solid state symmetric supercapacitor (SSC) with redox additive gel electrolyte achieves a maximum energy density (Es) of 31.5 Wh kg−1 at a power density (Ps) of 500 W kg−1. Furthermore, red LEDs are operated by the power source of two SSCs connected in the serial mode for 130 sec. This studies imply that utilizing CuO within redox additive electrolytes could present a simple and cost-effective approach for developing high-energy storage supercapacitors.

A redox additive electrolyte boosted supercapacitive energy density of wrinkled RGO sheets

Redox additive (RA)-based electrolytes have emerged as a promising approach to enhance the performance of carbon-based supercapacitors (SCs) as they bestow the additional pseudocapacitance to carbon and enhance its energy density (Ed). The present study demonstrates the enhanced supercapacitive Ed of reduced graphene oxide (RGO) electrodes by employing an RA of 0.05 M K4[Fe(CN)6] (KFC) in 0.5 M K2SO4 (K2) electrolytes. To enhance the active surface area (confirmed by N2 absorption- desorption) with minor agglomeration (confirmed by morphological analysis) and less defective (confirmed by Raman analysis) wrinkled RGO sheets were synthesized through thermal reduction of GO. The RGO electrode obtained 3 times higher specific capacitance (CS) in K2+ KFC as compared to the K2 electrolyte. The assembled RGO-based symmetric aqueous device shows CS of 79.5 F/g and 66 mAh/g of specific capacity (CPS) at 5 mV/s with 36.8 Wh/kg Ed, 1.2 kW/kg of Pd at 15 mA, and 134 % capacitance retention over 5000 galvanostatic charge-discharge cycles in K2 + KFC electrolyte. The obtained results demonstrated the incorporation of a tiny amount of RA in supporting electrolytes can significantly enhance the electrochemical performance and pave the way for future advanced energy storage technology.

Doable high energy density supercapacitors using rice husk-derived carbon in dihydroxybenzenes as redox-additive electrolytes

Though activated carbon made from various bio wastes is quite affordable and plentiful, the energy density of these electrodes in aqueous electrolytes is still questionable. Therefore, increasing the energy density of activated carbon for use in supercapacitors is a challenging issue. The ideal way to boost the energy density of supercapacitors in aqueous electrolytes is by using redox-additive electrolytes. Redox-additive electrolytes are the impeccable solution for thriving the energy density of supercapacitors in aqueous electrolytes. Here, three additives namely 1, 2-benzene diol, 1, 3-benzene diol, and 1, 4-benzene diol were utilized as redox-additives with 1 M H2SO4 to study the influence of the position of OH on their redox activity and electrochemical performance. The activated carbon derived from rice-husk delivered a high specific capacitance of 1414 F/g at 4 A/g with 1, 4-benzene diol/H2SO4 among the three redox additives. A symmetric supercapacitor was fabricated, which exhibited a remarkable energy density of 38 Wh/kg at 2 A/g with 1, 4-benzene diol/H2SO4, which is almost 4 times superior to the energy density of the same electrode with H2SO4 (10.6 Wh/kg at 2 A/g).

Redox additives dependent supercapacitor performances of ZnO/SnO2@MWCNT nanocomposites

The poor cyclic stability arose from the low conductivity and strong electrostatic interaction between the ions remain the formidable challenge on the development of ZnO/SnO2 based electrodes for high-performance supercapacitor devices. Herein, an effective strategy was developed to achieve the higher conductivity by the growth of ZnO/SnO2 nanocomposites (NCs) on multiwalled carbon nanotube (MWCNT) through hydrothermal approach. Physiochemical characteristics of the synthesized ZnO/SnO2@MWCNT (ZSM) NCs were investigated by the XRD, FT-IR, SEM, HR-TEM, and XPS analyses. The fabricated working electrodes performances were examined for supercapacitor devices under pure 1 M Na2SO4 (NSE) and 0.1 M K4[Fe(CN)6] added redox additive electrolytes (RAE). The fabricated working electrode showed 297 Fg−1 specific capacitance in NSE and it was increased to 3885 Fg−1 under RAE. The fabricated working electrode possessed the cyclic retention of 81.15 % even after consecutive 5000 GCD cycles and it was enhanced up to 84.42 % in RAE. Also, incorporation of redox additives, greatly enhanced the energy and power densities of the fabricated device and they were found to be 22.50 Whkg−1 and 3200 Wkg−1, respectively in RAE. It confirmed that the incorporation of MWCNT in electrode material and RAE, greatly improved the overall efficiency of the ZnO/SnO2 based supercapacitors.

Study of [EMIM] [EtSO4] ionic liquid-based gel polymer electrolyte mediated with hydroquinone redox additive for flexible supercapacitors

Gel Polymer Electrolytes (GPEs) are considered as suitable candidates in the design of energy storage devices like flexible supercapacitors due to their higher safety and flexibility. Incorporating small quantity of redox additives in GPE significantly improves their conductivity and is considered as an innovative method to enhance the capacitance of supercapacitors, because both electrolyte and electrode materials contribute to the capacitance. In this work, performance of Flexible Supercapacitor's (FSCs) using symmetrical Laser Induced Graphene (LIG) as electrodes and ionic liquid 1-Ethyl-3-Methylimidazolium Ethyl Sulfate [EMIM] [EtSO4] incorporated in Gel Polymer Electrolyte (GPE) with and without redox additive Hydroquinone (HQ) is presented. Upon electrochemical characterization using Galvanostatic Charge Discharge (GCD), it was found that the FSC with redox additive showed highest areal capacitance and energy density of 15.1 mFcm−2 and 1.54 μWhcm−2 respectively and FSC without redox additive showed an areal capacitance and energy density of 1.94 mFcm−2 and 0.14 μWhcm−2 respectively at 2 mAcm−2. The device with redox additive also showed 100 % columbic efficiency after 50 cycles and maintained 80 % capacitance for 5000 charge-discharge cycles. Additionally, the electrolyte with the redox additive showed superior conductivity of 10.8 mScm−1, demonstrating that modifying electrolyte by adding redox additive has been a simple yet effective method to enhance the overall performance of FSCs. Also, the synthesized LIG was characterized by X-ray Diffraction (XRD), Raman and Scanning Electron Microscopy techniques which confirmed the formation of bi-layer porous graphene.

Dye-sensitized solar cell employing chitosan-based biopolymer electrolyte

Conductivity and transport properties of a cost-effective and environment friendly chitosan based solid biopolymer electrolytes which form mechanically robust thick film, have been reported here. A maximum ionic conductivity of ∼ 10-4 S/cm has been achieved by optimizing the concentrations of the salt (LiClO4) and the plasticizer (EC) in the biopolymer electrolyte. Ion transport properties of the biopolymer electrolytes are studied from Raman spectroscopy. A dye-sensitized solar cell (DSSC), with a sandwich structure, is fabricated with chemically synthesized ZnO (∼ 60 nm) as the nanoporous semiconductor material coated with Rose Bengal dye as a photosensitizer, the chitosan biopolymer as electrolyte and platinum as counter electrode. Linear Sweep Voltammetry analysis of the DSSCs illustrates the photovoltaic performance of these cells. Without any external addition of redox couple in the biopolymer electrolytic system, a maximum short-circuit current density of JSC = 0.556 mA/cm2 and open-circuit voltage Voc = 0.605 V with power conversion efficiency 0.051 % is achieved by the DSSC.

Designed Redox‐Electrolyte Strategy Boosted with Electrode Engineering for High‐Performance Ti3C2Tx MXene‐Based Supercapacitors

AbstractTi3C2Tx MXene has shown remarkable potential for supercapacitors. However, its limited capacitance restrains the energy density. Here, a designed redox‐electrolyte strategy boosted with electrode engineering for Ti3C2Tx MXene is demonstrated, by which a record‐high specific capacitance of 788.4 F g−1 at 2 mV s−1 is achieved, accompanied by good rate capability and highly improved cyclic stability compared with the pristine MXene electrode. For the first time, redox additives with redox potentials falling in the Ti3C2Tx MXene's potential range and that can take full advantage of the characteristics of Ti3C2Tx MXene are investigated. CuSO4 and VOSO4 are screened as the hybrid redox additives; and it is revealed that copper and vanadium ions can bond with ═O terminals on the MXene surface and undergo redox reactions mainly via Cu2+/Cu+ and V3+/V2+. The electrode engineering significantly boosts the designed redox‐electrolyte strategy by enhancing ion dynamics and increasing electrochemically active sites. High energy density of 80.9 Wh kg−1 at a power density of 376.0 W kg−1 and high cyclic stability and improved self‐discharging behavior are obtained for the fabricated supercapacitor by applying this strategy. The strategy is also demonstrated for the performance improvement of MXene‐based flexible supercapacitors with hydrogel electrolytes.

Cucumis melo var agrestis based activated carbon/manganese ammonium phosphate @ carbon hollow sphere in dual redox additives for supercapattery device

AbstractThe electrochemical performance of manganese ammonium phosphate (MnAP) intercalated carbon hollow sphere (CS) at four mass variates has been investigated. The XRD, Raman, SEM, and electrochemical studies reveal that only 50 mg of CS strongly intercalating with MnAP (MnAP@CS2) is observed. The half‐cell test has shown the profound pseudocapacitance for 50 mg intercalated MnAP@CS2 hybrid composite (2545 C g−1 @ 1 A g−1 in KI added 2 M H2SO4) and confirms the imminence of optimal mass concentration of CS with MnAP and the effect of KI redox additive towards enhancing the specific capacity. The supercapattery hybrid device (SBHD) using MnAP@CS2 as the positive electrode and as newly synthesized activated carbon (AC) derived from cucumis melo var agrestis as a negative electrode is examined in pure 3 M H2SO4 and in 0.025 M KI/VOSO4 dual redox additive added 3 M H2SO4. The exquisite complacency requisite on specific capacitance (536 C g−1/149 mAh g−1 @ 1 A g−1 @ 20 A g−1), energy density (80 Wh g−1), and capacity retention (89% for 5000 charge‐discharge cycles) have profusely advocating MnAP@CS2 and AC for SBH device applications.

Large-scale vertical graphene on nickel foil as a binder-free electrode for high performance battery-like supercapacitor with an aqueous redox electrolyte

Due to the special three-dimensional structures and excellent physicochemical properties, vertical graphene (VG) has been extensively investigated as potential material for supercapacitors. However, achieving VG-based supercapacitors with high-energy density and high-power density is a still tremendous challenge. Here we attempt to synthesize large-scale VG films on flexible substrates and design a novel battery-like supercapacitor (BSCs) with the VG on Ni foil (VG@Ni) as a binder-free electrode operating in the KOH electrolyte with the redox additives of K3Fe(CN)6 and/or K4Fe(CN)6. The VG@Ni electrodes demonstrate an ultrahigh areal capacitance of 1453 mF cm−2 at 5 mA cm−2 in 1 M KOH electrolyte with adding 0.07 M K3Fe(CN)6 and 0.07 M K4Fe(CN)6, coulombic efficiency greater than 90%, and long-life cycling stability (capacitance retention is 99.3% after 20000 charge-discharge cycles). The BSCs, which are assembled with two identical VG@Ni electrodes, deliver the areal capacitance of 231 mF cm−2 with energy density of 32 μWh cm−2 and power density of 2498 μW cm−2 at 1 mA cm−2. These outstanding performances can be ascribed to the special feature and excellent properties of VG materials, high electronic conductivity of binder-free VG@Ni electrode, faradaic properties of redox electrolyte, and synergistic effects between the VG film and redox electrolyte.