Protic ionic liquid-based gel polymer electrolyte: structural and ion transport studies and its application in proton battery

Proton-conducting free standing gel polymer electrolyte (GPE) films containing protic ionic liquid, 1-butyl-3-methylimidazolium hydrogen sulphate, immobilized in blend of poly(vinylidenefluoride-co-hexafluoropropylene) and poly(vinylpyrrolidone) have been prepared by solution-cast technique. Films have been characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM), differential scanning calorimetry (DSC), complex impedance spectroscopy, and cyclic voltammetry. Ionic conductivity of the semicrystalline and porous GPE films has been obtained as ~3.9?×?10^?3 S cm^?1 at room temperature. Protonic nature of conduction in the films has been established by performing cyclic voltammetry and complex impedance spectroscopy on the cells having both blocking (stainless steel) and both reversible electrodes (Zn + ZnSO₄.7H₂O). The electrochemical stability window of the films has been found as ~3.8 V. The highest conducting film has been used as a separator and proton conductor to fabricate a proton battery of configuration Zn + ZnSO₄.7H₂O |GPE film| PbO₂ + V₂O₅. The battery shows an open circuit voltage of ~1.62 V. Energy density of the cell has been obtained as 35.2 W h kg^?1 for low current drain. Rechargeability of the cell has been tested for ten cycles. The maximum discharge capacity of the cell has been obtained as ~2.50 mA h g^?1 during the first discharge cycle.     

Enhanced ionic conductivity in novel nanocomposite gel polymer electrolyte based on intercalation of PMMA into layered LiV3O8

In the present work, a novel polymer electrolyte based on poly(methyl methacrylate) (PMMA)/layered lithium trivanadate (LiV₃O₈) nanocomposite has been investigated. X-ray diffraction (XRD) study shows that d-spacing is increased from 6.3?±?0.1 Å to 12.8?±?0.1 Å upon intercalation of the polymer into the layered LiV₃O₈. Room temperature ionic conductivity of the obtained nanocomposite gel polymer electrolyte is found to be superior to that of conventional PMMA-based gel polymer electrolyte. Enhancement in ionic conductivity of the nanocomposite gel electrolyte is attributed to the formation of a two-dimensional channel as a result of decreased interaction between Li⁺ and V₃O ₈ ^? layers as confirmed by FTIR. SEM results show aggregation of nanocomposite particles resulting from extension of some of the polymer chains from interlayer to the edge providing paths for Li⁺ ion transport. Interfacial stability of nanocomposite gel electrolyte is also found to be better than that of the conventional PMMA-based gel polymer electrolyte.     

Enhanced zinc ion transport in gel polymer electrolyte: effect of nano-sized ZnO dispersion

The effect of the dispersion of zinc oxide (ZnO) nanoparticles in the zinc ion conducting gel polymer electrolyte is studied. Changes in the morphology/structure of the gel polymer electrolyte with the introduction of ZnO particles are distinctly observed using X-ray diffraction and scanning electron microscopy. The nanocomposites offer ionic conductivity values of >10^?3 S cm^?1 with good thermal and electrochemical stabilities. The variation of ionic conductivity with temperature follows the Vogel–Tamman–Fulcher behavior. AC impedance spectroscopy, cyclic voltammetry, and transport number measurements have confirmed Zn²⁺ ion conduction in the gel nanocomposites. An electrochemical stability window from ?2.25 to 2.25 V was obtained from voltammetric studies of nanocomposite films. The cationic (i.e., Zn²⁺ ion) transport number (t ₊) has been found to be significantly enhanced up to a maximum of 0.55 for the dispersion of 10 wt.% ZnO nanoparticles, indicating substantial enhancement in Zn²⁺ ion conductivity. The gel polymer electrolyte nanocomposite films with enhanced Zn²⁺ ion conductivity are useful as separators and electrolytes in Zn rechargeable batteries and other electrochemical applications.     

Electrospun octa(3-chloropropyl)-polyhedral oligomeric silsesquioxane-modified polyvinylidene fluoride/poly(acrylonitrile)/poly(methylmethacrylate) gel polymer electrolyte for high-performance lithium ion battery

Gel polymer electrolyte (GPE) based on octa(3-chloropropyl)-polyhedral oligomeric silsesquioxane (OCP-POSS)-modified polyvinylidene fluoride/poly(acrylonitrile) /poly(methylmethacrylate) (PVDF/PAN/PMMA) fibrous membrane was prepared by electrospinning method to improve the thermal stability of GPE and prevent the leakage of liquid electrolyte for lithium ion battery. The effect of OCP-POSS content on the morphology, porosity and electrolyte uptake, mechanical strength, thermal stability of spinning fibrous membrane and ionic conductivity, electrochemical stability window, and interface resistance of GPE was investigated. The cycle performance of cells assembled with GPE was also tested. The results show that the spinning fibrous membrane with 10 wt% OCP-POSS possesses high electrolyte uptake (660%) and excellent thermal stability. The ionic conductivity of corresponding GPE is 9.23 × 10^?3 S cm^?1 at room temperature and the electrochemical stability window is up to 5.82 V; the interface resistance of 10 wt% OCP-POSS modified GPE decreases by 42% after 168 h compared with pure PVDF/PAN/PMMA GPE. Furthermore, cells assembled with 10 wt% OCP-POSS modified GPE show high discharge capacity (166.5 mA h g^?1 at 0.1 C) and excellent cycle stability during 50 cycles. The results indicate that the GPE could improve the safety of lithium ion battery and show great potential in lithium ion battery applications.     

Electrospun cellulose acetate/poly(vinylidene fluoride) nanofibrous membrane for polymer lithium-ion batteries

The membranes for gel polymer electrolyte (GPE) for lithium-ion batteries were prepared by electrospinning a blend of poly(vinylidene fluoride) (PVdF) with cellulose acetate (CA). The performances of the prepared membranes and the resulted GPEs were investigated, including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), porosity, hydrophilicity, electrolyte uptake, mechanical property, thermal stability, AC impedance measurements, linear sweep voltammetry, and charge–discharge cycle tests. The effect of the ratio of CA to PVdF on the performance of the prepared membranes was considered. It is found that the GPE based on the blended polymer with CA:PVdF =2:8 (in weight) has an outstanding combination property-strength (11.1 MPa), electrolyte uptake (768.2 %), thermal stability (no shrinkage under 80 °C without tension), and ionic conductivity (2.61 × 10^?3 S cm^?1). The Li/GPE/LiCoO₂ battery using this GPE exhibits superior cyclic stability and storage performance at room temperature. Its specific capacity reaches up to 204.15 mAh g^?1, with embedded lithium capacity utilization rate of 74.94 %, which is higher than the other lithium-ion batteries with the same cathode material LiCoO₂ (about 50 %).     

A novel gel polymer electrolyte based on lithium salt with an ethyl cellulose

A novel gel polymer electrolyte (GPE) that contains Li⁺ ions was fabricated. An appropriate amount of ethyl cellulose (EC) was added to 1 M lithium perchlorate in propylene carbonate to prepare the GPE. The ionic conductivity (σ) of the GPE depends on the EC content, and the GPE with an EC content of 4.5 wt.% exhibits a maximum σ of 6.47 mS/cm, a viscosity of 141 mPa?s, and a transmittance of over 80% (visible region) at room temperature. High σ and transparent GPE can be obtained. In this work, the EC was used as natural thickener to enhance the viscosity of the liquid-state electrolyte and could improve the leakage of electrolyte solution.     

Effect of plasticizers (EC or PC) on the ionic conductivity and thermal properties of the (PEO)9LiTf: Al2O3 nanocomposite polymer electrolyte system

A new plasticized nanocomposite polymer electrolyte based on poly (ethylene oxide) (PEO)-LiTf dispersed with ceramic filler (Al₂O₃) and plasticized with propylene carbonate (PC), ethylene carbonate (EC), and a mixture of EC and PC (EC+PC) have been studied for their ionic conductivity and thermal properties. The incorporation of plasticizers alone will yield polymer electrolytes with enhanced conductivity but with poor mechanical properties. However, mechanical properties can be improved by incorporating ceramic fillers to the plasticized system. Nanocomposite solid polymer electrolyte films (200–600 μm) were prepared by common solvent-casting method. In present work, we have shown the ionic conductivity can be substantially enhanced by using the combined effect of the plasticizers as well as the inert filler. It was revealed that the incorporating 15 wt.% Al₂O₃ filler in to PEO: LiTf polymer electrolyte significantly enhanced the ionic conductivity [σ _RT (max)?=?7.8?×?10^?6 S cm^?1]. It was interesting to observe that the addition of PC, EC, and mixture of EC and PC to the PEO: LiTf: 15 wt.% Al₂O₃ CPE showed further conductivity enhancement. The conductivity enhancement with EC is higher than PC. However, mixture of plasticizer (EC+PC) showed maximum conductivity enhancement in the temperature range interest, giving the value [σ _RT (max)?=?1.2?×?10^?4 S cm^?1]. It is suggested that the addition of PC, EC, or a mixture of EC and PC leads to a lowering of glass transition temperature and increasing the amorphous phase of PEO and the fraction of PEO-Li⁺ complex, corresponding to conductivity enhancement. Al₂O₃ filler would contribute to conductivity enhancement by transient hydrogen bonding of migrating ionic species with O–OH groups at the filler grain surface. The differential scanning calorimetry thermograms points towards the decrease of T _g , crystallite melting temperature, and melting enthalpy of PEO: LiTf: Al₂O₃ CPE after introducing plasticizers. The reduction of crystallinity and the increase in the amorphous phase content of the electrolyte, caused by the filler, also contributes to the observed conductivity enhancement.     

Influence of solvent type on porosity structure and properties of polymer separator for the Li-ion batteries

Polyethylene-supported polymethyl methacrylate/poly(vinylidene fluoride-co-hexafluoropropylene) separator for gel polymer lithium-ion battery use was prepared with a mixed solvent of n-butanol and acetone. The prepared separator was characterized with scanning electron spectroscopy and X-ray diffraction, and its performance was investigated by electrochemical impedance spectroscopy and battery charge/discharge test. Compared to the separator prepared with acetone, the separator prepared with the mixed solvent shows an enhanced porosity (from 42 to 49 %) and electrolyte uptake (from 104 to 125 %). The ionic conductivity of the corresponding gel polymer electrolyte is improved from 2.81 to 3.39 mS cm^?1, the discharge capacity retention of the LiCoO₂/artificial graphite battery is increased from 95 to 98 % after 100 cycles at 0.5 C, and the discharge capacity of the battery at 1 C increases by 4 %.     

Effect of styrene–acrylonitrile content on 0.5?M NaI/0.05?M I2 liquid electrolyte encapsulation for dye-sensitized solar cells

The effect of a gel polymer electrolyte (GPE) as the redox electrolyte used in dye-sensitized solar cells was studied. A GPE solution consisting of 0.5?M sodium iodide, 0.05?M iodine, and ethylene carbonate/propylene carbonate (1:1 w/w) binary solvents was mixed with increasing amounts of styrene–acrylonitrile (SAN). Bulk conductivity measurements show a decreasing trend from 4.54 to 0.83×10^?3?S?cm^?1 with increasing SAN content. The GPE exhibits Newtonian-like behavior and its viscosity increases from 0.041 to 1.093?Pa?s with increasing SAN content. A balance between conductivity (1.3?×?10^?3?S?cm^?1) and viscosity (1.4?Pa?s) is observed at 19?wt.% SAN. Fourier transform infrared spectroscopy detects elevated ring torsion at 706?cm^?1 upon the addition of SAN into the liquid electrolyte. This indicates that SAN does not bond with the liquid electrolyte. Finally, the potential stability window of 19?wt.% SAN, which ranges from ?1.68 to 1.38?V, proves its applicability in solar cells.     

Cross-linking copolymers of acrylates’ gel electrolytes with high conductivity for lithium-ion batteries

The cross-linking gel copolymer electrolytes containing alkyl acrylates, triethylene glycol dimethacrylate, and liquid electrolyte were prepared by in situ thermal polymerization. The gel polymer electrolytes containing 15 wt% polymer content and 85 wt% liquid electrolyte content with sufficient mechanical strength showed the high ionic conductivity around 5?×?10^?3 Scm^?1 at room temperature. The gel electrolytes containing different polymer matrices were prepared, and their physical observation and conductivity were discussed carefully. The cross-linking copolymer gel electrolytes of alkyl acrylates with other monomers were designed and synthesized. The results showed that copolymerization can improve the mechanical properties and ionic conductivities of the gel electrolytes. The polymer matrices of gels had excellent thermal stability and electrochemical stability. The scanning electron microscope analysis showed the gel electrolyte was the homogeneous structure, and the cross-linking polymer host was the porous three-dimensional network structure, which demonstrated the high conductivity of the gel electrolytes. The gel polymer Li-ion battery was prepared by this in situ thermal polymerization. The cell exhibited high charge-discharge efficiency at 0.1 C. The results of LiFePO4-PEA-Li cell and graphite-PEA-Li cell showed that gel polymer electrolytes have good compatibility with the battery electrodes materials.     

Enhanced electrochemical properties of a novel polyvinyl formal membrane supporting gel polymer electrolyte by Al2O3 modification

Polyvinyl formal (PVFM)‐based dense polymer membranes with nano‐Al₂O₃ doping are prepared via phase inversion method. The membranes and also their performances as gel polymer electrolytes (GPEs) for lithium ion battery are studied by field emission scanning electron microscope, X‐ray diffraction, differential scanning calorimetry, mechanical strength test, electrolyte uptake test, electrochemical impedance spectroscopy, cyclic voltammetry, and charge–discharge test. The polymer membrane with 3 wt % nano‐Al₂O₃ doping shows the improved mechanical strength of 12.16 MPa and electrolyte uptake of 431.25% compared with 10.47 MPa and 310.59% of the undoped sample, respectively. The membrane absorbs and swells liquid electrolyte to form stable GPE with ionic conductivity of 4.92 × 10^?4 S cm^?1 at room temperature, which is higher than 1.77 × 10^?4 S cm^?1 of GPE from the undoped membrane. Moreover, the Al₂O₃‐modified membrane supporting GPE exhibits wide electrochemical stability window of 1.2–4.8 V (vs. Li/Li⁺) and good compatibility with LiFePO₄ electrode, which implies Al₂O₃‐modified PVFM‐based GPE to be a promising candidate for lithium ion batteries. © 2014 Wiley Periodicals, Inc. J. Polym. Sci. Part B: Polym. Phys. 2014 , 52, 572–577     

Influence of barium titanate nanofiller on PEO/PVdF-HFP blend-based polymer electrolyte membrane for Li-battery applications

Organic-inorganic hybrid membranes based on poly(ethylene oxide) (PEO) 6.25 wt%/poly(vinylidene fluoride hexa fluoro propylene) [P(VdF-HFP)] 18.75 wt% were prepared by using various concentration of nanosized barium titanate (BaTiO₃) filler. Structural characterizations were made by X-ray diffraction and Fourier transform infrared spectroscopy, which indicate the inclusion of BaTiO₃ in to the polymer matrix. Addition of filler creates an effective route of polymer-filler interface and promotes the ionic conductivity of the membranes. From the ionic conductivity results, 6 wt% of BaTiO₃-incorporated composite polymer electrolyte (CPE) showed the highest ionic conductivity (6 × 10^?3 Scm^?1 at room temperature). It is found that the filler content above 6 wt% rendered the membranes less conducting. Morphological images reveal that the ceramic filler was embedded over the membrane. Thermogravimetric and differential thermal analysis (TG-DTA) of the CPE sample with 6 wt% of the BaTiO₃ shows high thermal stability. Electrochemical performance of the composite polymer electrolyte was studied in LiFePO₄/CPE/Li coin cell. Charge-discharge cycle has been performed for the film exhibiting higher conductivity. These properties of the nanocomposite electrolyte are suitable for Li-batteries.     

Fabrication and characterization of electrochemical double layer capacitors using ionic liquid-based gel polymer electrolyte with chemically treated activated charcoal electrodes

The present investigation deals with electrochemical double layer capacitors (EDLCs) made up of ionic liquid (IL)-based gel polymer electrolytes with chemically treated activated charcoal electrodes. The gel polymer electrolyte comprising of poly(vinylidine fluoride-co-hexafluropropylene) (PVdF-HFP)–1-ethyl-2,3-dimethyl-imidazolium-tetrafluroborate [EDiMIM][BF₄]–propylene carbonate (PC)–magnesium perchlorate (Mg(ClO₄)₂) exhibits the highest ionic conductivity of ~8.4?×?10^?3?S?cm^?1 at room temperature (~20 °C), showing good mechanical and dimensional stability, suitable for their application in EDLCs. Activation of charcoal was done by impregnation method using potassium hydroxide (KOH) as activating agent. Brunauer–Emmett–Teller (BET) studies reveal that the effective surface area of treated activated charcoal powder (1,515 m²?g^?1) increases by more than double-fold compared to the untreated one (721 m²?g^?1). Performance of EDLCs has been tested using cyclic voltammetry, impedance spectroscopy, and charge–discharge techniques. Analysis shows that chemically treated activated charcoal electrodes have almost triple times more capacitance values as compared to the untreated one.     

A novel polyacrylonitrile-based porous structure gel polymer electrolyte composited by incorporating polyhedral oligomeric silsesquioxane by phase inversion method

A novel polyhedral oligomeric silsesquioxane (POSS) composite polyacrylonitrile (PAN)-based porous structure gel polymer electrolyte (GPE) is prepared by phase inversion method. The POSS additive filler is firstly obtained in the dehydration condensation reaction of vinyltrimethoxysilane (VTMS) and 3-methacryloxypropyltrimethoxysilane (MPTMS). The composition and structure of synthetic POSS and the prepared POSS composite PAN-based GPEs are investigated. It is found that compared with pure PAN-based GPE, the POSS composite PAN-based GPE with 8 wt.% POSS presents the homogeneous pore distribution and abundant electrolyte uptake (540.4 wt.%), which endows GPE-8% with the excellent comprehensive performances: the highest ionic conductivity of 2.62?×?10^?3 S cm^?1 at room temperature, the higher lithium ion transference number of 0.38, the good compatibility with lithium anode, and the higher electrochemical stability window of 5.7 V (vs. Li/Li⁺). At 0.2 C, the GPE-8%-based lithium ion battery produces a satisfactory discharge capacity of 140 mAh g^?1.

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The short-term cycling properties of Na/PVdF/S battery at ambient temperature

The Na/PVdF/S cells were composed of solid sodium, sulfur, and polyvinylidene fluoride–hexafluoropropene (PVdF) gel polymer electrolyte. The PVdF polymer electrolyte was prepared form tetraglyme plasticizer and NaCF₃SO₃ salt, and its electrochemical properties were studied using CV and impedance analysis. The interfacial resistance between sodium and polymer electrolyte increase with storage time, which might be associated with passivation layer. Solid-state sodium/sulfur cell using a PVdF gel polymer electrolyte has been tested. The Na/PVdF/S cell with 0.288 mA cm^?2 shows a high discharge capacity of 392 mAh g^?1 and 36 mAh g^?1 after 20 cycles. The cycle performance of Na/GPE/S cell operating at 25 °C is worse than Na/S cell at a high temperature.     

Proton-conducting membranes: poly (N-vinyl pyrrolidone) complexes with various ammonium salts

The present study focuses on the proton-conducting polymer electrolytes; poly (N-vinyl pyrrolidone)–ammonium thiocyanate and poly (N-vinyl pyrrolidone)–ammonium acetate prepared by solution casting technique. The XRD analysis indicates the amorphous nature of the polymer electrolytes. The Raman spectra of the C=O vibration of pure polymer PVP at 1,663 cm^?1 has been appeared as doublet in the polymer electrolytes. The introduction of this new peak in the salt-doped polymer electrolytes may be due to interaction of the cation with the polymer. The room temperature ionic conductivity σ _303κ has been found to be high, 1.7?×?10^?4 S cm^?1 for 80 mol% PVP–20 mol% NH₄SCN and 1.5?×?10^?6 S cm^?1 for 75 mol% PVP–25 mol% CH₃COONH₄. The polymer electrolytes have been tested for their application in Zn–air battery.     

Polyacrylamide-methanesulfonic acid gel polymer electrolytes for tin-air battery

The present work describes the synthesis and characterization of gel polymer electrolytes containing methanesulfonic acid (MSA) with Polyacrylamide (PAAm). The PAAm–MSA gel electrolytes were prepared with different concentrations of MSA. Addition of 0.5 M of MSA into the electrolyte increased the ionic conductivity of PAAm from 1.35 × 10^?3 to 1.56 × 10^?2 S cm^?1. The maximum ionic conductivity of 7.0 × 10^?1 S cm^?1 was obtained with 3 M MSA at room temperature. The chemical interaction between PAAm and MSA was studied by Fourier transformed infra-red. The performance as a polymer electrolyte was evaluated from the cell discharge and open circuit potential measurements of a tin-air cell. The tin-air cell supported relatively high current, up to 12 mA cm^?2 with a maximum power density of 5 mW cm^?2. The open-circuit potential of the cell was 1.27 V for 24 h.     

Dielectric and conductivity studies of 90 MeV O7+ ion irradiated poly(ethylene oxide)/montmorillonite based ion conductor

In the present work effect of 90 MeV O⁷⁺ ions with five different fluences on poly(ethylene oxide) (PEO)/Na⁺-montmorillonite (MMT) nanocomposites has been investigated. PEO/MMT nanocomposites were synthesized by solution intercalation technique. With the increase in irradiation fluence, gallery spacing of MMT increases in the composite and an exfoliated nanostructure is obtained at the fluence of 5?×?10¹² ions/cm² as revealed by X-ray diffraction results. Highest room temperature ionic conductivity of 4.2?×?10^?6?S?cm^?1 was found for the fluence 5?×?10¹² ions/cm², while the conductivity for unirradiated polymer electrolyte was found to be 7.5?×?10^-8?S?cm^?1. The increase in intercalation of PEO chains inside the galleries of MMT results in the increase in interaction between Na⁺ cation and oxygen heteroatom leading to the increase in ionic conductivity of the composites. Surface morphology and interactions among the various constituents in the nanocomposites at different fluence have been examined by scanning electron microscopy and Fourier transform infrared spectroscopy, respectively. The appearance of peak for each fluence in the loss tangent suggests the presence of relaxing dipoles in the polymer nanocomposite electrolyte films. With the increase in ion fluence the peak shifts towards higher frequency side, suggesting decrease in the relaxation time.     

Magnesium ion transport in poly(ethylene oxide)-based polymer electrolyte containing plastic-crystalline succinonitrile

A new composition of magnesium (Mg)-ion-conducting polymer electrolyte comprising poly(ethylene oxide) (PEO) complexed with Mg trifluoromethanesulfonate (Mg triflate or Mg(Tf)₂) containing different amounts of a nonionic plastic crystal succinonitrile (SN) has been prepared and characterized. High polarity and rotational disorder of the SN molecules in the plastic-crystalline phase, supports the enhancement of ionic conductivity of the PEO-Mg(Tf)₂ complex system, showing a maximum room temperature ionic conductivity of ～6?×?10^-4 S cm^?1 observed with the addition of 50 wt.% of SN. X-ray diffraction, optical microscopy, and differential scanning calorimetry suggest a substantial structural modification, decrease in crystallinity, and various interactions in the polymer electrolyte components due to addition of SN. The cyclic voltammetry, impedance, and dc polarization studies confirm the Mg-ion conduction in the PEO complex. The electrochemical potential window of the electrolyte, observed from the linear sweep voltammetry, is determined to be ～4.1 V. The performance characteristics of the SN-incorporated polymer electrolyte system indicate their potential applicability as electrolytes in ionic devices including Mg batteries.     

Polyethylene oxide-based nanocomposite polymer electrolytes for redox capacitors

In this work, the use of a polyethylene oxide-based nanocomposite polymer electrolyte (NCPE) in a redox capacitor with polypyrrole electrodes has been studied. To the best of our knowledge, not much work has been reported in the literature on redox capacitors fabricated using NCPEs. The composition of the polyethylene oxide (PEO)-based NCPE was fine tuned to obtain films with the highest ionic conductivity. They were mechanically stable to handle for any purpose without damaging the film. The optimized composition was {[(10PEO:NaClO₄) molar ratio]: 75 wt.% propylene carbonate (PC)}: 5 wt.% TiO₂. This electrolyte film showed an ambient temperature ionic conductivity of 5.42 × 10^?3 S cm^?1. It was employed in a redox capacitor with polypyrrole electrodes polymerized in the presence of sodium perchlorate in non-aqueous medium. Performance of the redox capacitors were observed using cycling voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge discharge test. It was possible to observe a satisfactory capacitive behavior in the range 58–83 F/g. Further, the redox capacitors had the ability to retain for continuous charge discharge processes.