Carbon-based Composite Electrode Research Articles

Employing Manganese Dioxide and Bamboo Carbon for Capacitive Water Desalination and Disinfection.

A manganese dioxide (MnO2)/bamboo carbon (BC) composite was prepared using hydrothermal and impregnation methods and used for the capacitive desalination (CDI) and disinfection of water. The results showed that these composites had fast Na+ ion exchange and charge transfer properties. During the CDI process, these composites' electrodes exhibited good cycle stability and electrosorption capacity (4.09 mg/g) and an excellent bactericidal effect. These carbon-based composite electrodes' bactericidal rate for Escherichia coli could reach 99.99% within 180 min; therefore, they had good performance and are a good choice for high-performance deionization applications.

A Unified Charge Storage Mechanism to Rationalize the Electrochemical Behavior of Quinone-Based Organic Electrodes in Aqueous Rechargeable Batteries.

Due to their eco-sustainability and versatility, organic electrodes are promising candidates for large-scale energy storage in rechargeable aqueous batteries. This is notably the case of aqueous hybrid batteries that pair the low voltage of a zinc anode with the high voltage of a quinone-based (or analogue of quinone-based) organic cathode. However, the mechanisms governing their charge-discharge cycles remain poorly understood and are even a matter of debate and controversy. No consensus exists on the charge carrier in mild aqueous electrolytes, especially when working in an electrolyte containing a multivalent metal cation such as Zn2+. In this study, we comprehensively investigate the electrochemical reactivity of two model quinones, chloranil, and duroquinone, either diluted in solution or incorporated into carbon-based composite electrodes. We demonstrate that a common nine-member square scheme proton-coupled electron transfer mechanism allows us to fully describe and rationalize their electrochemical behavior in relation to the pH and chemical composition of the aqueous electrolyte. Additionally, we highlight the crucial role played by the pKas associated with the reduced states of quinones in determining the nature of the charge carrier that compensates for the negative charges reversibly injected in the active material. Finally, contrary to the widely reported findings for Zn/organic batteries, we unequivocally establish that the predominant solid-state charge carriers in Zn2+-based mild aqueous electrolytes are not multivalent Zn2+ cations but rather protons supplied by the weakly acidic hexaaqua metal ions (i.e., [Zn(H2O)6]2+]).

Waste biomass-derived N, P co-doping carbon aerogel-coated CoxFe1−xP with modulated electron density for efficient electrooxidation of contaminants

Developing low-cost, green, high-performing electrode materials to address environmental pollutants and the energy crisis is significant but challenging. Herein, the bimetallic iron cobalt phosphide coated in waste biomass-derived N, P co-doping carbon (CoxFe1−xP@NPC) is constructed. Furthermore, the active site density and the water decomposition energy barrier of surface-coated NPC are modulated by optimizing the electronic structure of CoxFe1−xP via doping engineering. The Fe-modulated CoxFe1−xP@NPC exhibits a hierarchical porous self-supporting structure and excellent physical & chemical properties with excellent electrooxidation performance, achieving over 95% removal of TCH within 60 min. The density functional theory (DFT) calculations further confirms that N carries more positive charge and P carries more negative charge in the NPC of CoxFe1−xP@NPC with Fe modulation, which can promote the adsorption and dissociation of water molecules. Of note, Co0.75Fe025P@NPC displays a low water dissociation energy barrier to produce ·OH and a high energy barrier to produce O2 than its counterparts. This study offers new insight into controllable modulation of biomass carbon-based composite electrode catalytic activity for high-efficiency degradation of contaminants.

Anodic oxidation of thiosulfate ions at a carbon-based electrode with deposited Au-particles

In the present work, the anodic oxidation of thiosulfate ions in neutral electrolytes at a carbon-based composite electrode with deposited submicron gold particles was studied using the direct current voltammetry method. It is shown that the oxidation process is displayed in the voltammetric curves in the form of two peaks of anodic current, the magnitude of which depends on the experimental conditions. An explanation of the most probable mechanism of the oxidation reactions of S2O32– ions at an anodically polarized gold-containing electrode has been proposed. It has been shown a possibility to monitor low concentrations of thiosulfate ions (0.1-10 μM) using a current peak at potentials E>1.0 V (vs. Ag/AgCl/1M KCl). The accuracy parameters of the analytical procedure were verified, practical applications of the analytical method have been outlined.

2,6-diaminoanthraquinone anchored on functionalized biomass porous carbon boosts electrochemical stability for metal-free redox supercapacitor electrode

The challenge of redox-active molecules for electrochemical capacitors is that they are easy to detach from the substrate during long-term charge-discharge cycles. In this work, redox-active molecule 2,6-diaminoanthraquinone (DAQ) is anchored on amino functionalized biomass porous carbon (FWS) via strong hydrogen bonding interaction. The protophilic C = O sites on the DAQ provide additional faradaic pseudocapacitance for biomass carbon-based electrode through fast redox reactions. In addition, the surface functionalization of porous carbon enhanced the interaction between the porous carbon and DAQ molecule, which inhibited the detachment of DAQ and significantly improved the electrochemical stability of the composite electrode. The optimized DAQ@FWS composite exhibits excellent specific capacitance of 424.9 F g−1 at 1 A g−1 with a stable capacity retention of 93.1% over 10,000 cycles at 10 A g−1, which is higher than unfunctionalized biomass porous carbon-based composite electrode (71.6% after 10,000 cycles). Meanwhile, DAQ@FWS composite maintains a high capacitance of 300.4 F g−1 even at 30 A g−1. Density functional theory calculations and detailed electrochemical analysis further elucidate the binding interactions of DAQ with FWS and charge storage mechanisms. Furthermore, coin-type symmetric supercapacitor based on DAQ@FWS exhibits excellent energy density (36.4 Wh kg−1 at 700.5 W kg−1), power density (7.001 kW kg−1 at 27.0 Wh kg−1) and durable cycling stability (capacitance retention is 88.3% after 10,000 cycles). Thus, amino functionalization of biomass porous carbon to anchor redox active organic quinones is promising as an effective strategy to fabricate superior performance supercapacitor electrode material.

Design of Boron Carbonitrides-Polyaniline (BCN-PANI) assembled supercapacitor with high voltage window

Boron carbonitrides (BCN) have been widely concerned in the field of energy storage and conversion. However, the energy storage mechanism of electrical double-layer behavior and their stacked-layer structure severely limit the improvement of capacitance, thereby hindering their further development in energy storage. Therefore, an ultrasonic-ball milling method was first chosen to obtain BCN nanosheets, together with a feasible way of polyaniline (PANI) modification performed to boost the capacitive reaction of BCN nanosheets. For the first time, a BCN-PANI-based symmetric supercapacitor device can reach a high voltage window of 3.0 V when 1 M Et4N·BF4 was chosen as the electrolyte. The working voltage of 3.0 V is three times that of a device with pure PANI with the ultrahigh energy density of 67.1 W h kg−1, superior to most of the reported PANI-based devices. The eminent electrochemical performance provides a promising strategy to pave the way for configuring carbon-based multiple composite electrodes for other energy storage devices.

Effects of carbon nanomaterials and MXene addition on the performance of nitrogen doped MnO2 based supercapacitors

Nitrogen-doped composites have the potential to achieve well electrochemical performance by enabling convenient contact of the electrolyte ions for carbon-based materials. A good combination of metal oxide and carbonaceous material is a critical challenge in the development of composites. Herein, we demonstrate a highly capacitive and superior cycle performance of MnO2 based supercapacitor electrodes. The addition of different forms of carbon nanomaterials (carbon nanotube and graphene) and MXene is particularly studied. MnO2 based composite materials are capable of capacitance retention over 95%, with high specific capacitance compared to pure N-doped MnO2. The highest specific capacitance was achieved with MXene based MnO2 composite, which exhibits 457 Fg-1, at a current density of 1 A g−1 with extreme cycling efficiency (102.5%, after 1000 cycles). High conductivity and large surface area are stimulated by the propitious interaction between MnO2 and nanoscale materials, resulting in superior supercapacitor efficiency. This study highlights the possible potential of carbon-based MnO2 composite electrodes which could be useful for future energy storage applications.

The development of novel cost‐effective bio‐electrolyte with glycerol host for carbon‐based flexible supercapacitor applications

Extensive attention has been given for the fabrication of stable and cost-effective electrolytes materials for wearable energy storage systems. Herein, glycerol (Gly) and H3PO4 (P) based bio-electrolyte for electrical double layer capacitance (EDLC) was produced and then converted to redox-mediated gel bio-electrolytes via doping with cobalt ions (Co) at various compositions to form glycerol-H3PO4-Co (GlyPCoX; X: 1%, 3%, 5%, 10% w/w). The gel electrolyte forms a hierarchical framework for effective ion conduction between the pores of the carbon composite electrodes that is triggered by bias during charging and discharging processes. The supercapacitors (SCs) were assembled with activated carbon-based composite electrodes and device performances were tested according to redox-mediated electrolyte compositions. Remarkable device performance was obtained from the Gly, which contained 5 M H3PO4 (P5) and 5% Co (Co5), (GlyP5Co5) and showed a specific capacitance of 349 F g−1. The corresponding specific energy and specific power were calculated as 47 and 420 W kg−1. Excellent operational stability (91%) was obtained after 15 000 charge/discharge cycles. In addition, the electrolyte is cost effective, retained extraordinary performance during galvanostatic charge-discharge (GCD), and successfully powered light-emitting diode (LED) device (1-4 cm) at various bending angles. Thus, the gel electrolyte has excellent stability and flexibility for use in wearable energy storage systems.

Intrinsic defects promote rapid conversion of polysulfides on carbon surface to achieve high rate performance

Polysulfides can be captured rapidly by defects, which possess strong catalytic redox abilities. Species of defects have important influence on rate performance of metal-sulfur electrodes. However, catalytic reaction mechanisms have not been explored in depth. This paper focuses on comparing differences between intrinsic defect carbon materials (IDC) and external introduced defect carbon materials (EIDC) in promoting polysulfide redox abilities and exploring catalytic redox reaction mechanism deeply. Results show that IDC have stronger catalytic redox reaction abilities than EIDC, which is mainly due to stable C–S bonds on surface of IDC. After cycling, C–S bond contents in IDC electrodes maintain more than 70 %. During cycling process, C–S bonds can quickly adsorb polysulfides and promote their conversion into final products, thereby achieving high rate performance. Weak catalytic redox abilities of EIDC electrodes is mainly due to loss of C–S bonds. When the current density is 5C, capacities of IDC electrodes is twice as much as that of EIDC electrodes. Good rate performance of IDC electrodes reflects important roles of stable C–S bonds in promoting redox reaction of polysulfides, which has important research significance for preparation of carbon-based composite electrodes.

Facile synthesis of new hybrid electrode material based on activated carbon/multiwalled carbon nanotubes@ZnFe2O4 for supercapacitor applications

A new hybrid composite of activated carbon (AC)/multiwalled carbon nanotubes (MWCNTs)-ZnFe2O4 has been prepared by the modest and low-cost method for its application as supercapacitor electrode material. The carbon-based composite electrode gives excellent cycle stability with moderate capacitance. So the capacitance of carbon-based composite electrode could be further improved by incorporating metal oxides as they involve reversible redox reaction. In this regard, zinc ferrite (ZnFe2O4) among various metal oxides is being considered as important additive material towards supercapacitor (SC) applications owing to its excellent physical and chemical properties. Hence, ZnFe2O4 is integrated with the carbon composite of MWCNTs and AC for better SC performance and cycle stability. The composite has resulted in maximum specific capacitance of 613 F/g at 5 mV/s when measured from cyclic voltammetry (CV) in 3 M KOH electrolyte. The measurement from galvanostatic charge–discharge (GCD) on synthesised composite has shown capacitance of 609 F/g at 1 A/g and that implying the significant storage performance of the prepared hybrid material. The stability, which is vital for the application of the composite, has been subjected for stability test and found that it retained 91% of the capacitance even after 10,000 cycles. Further, the synthesised materials have been characterized by powder X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), high-resolution transmission electron microscope (HRTEM), Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH). The variation of current as a function of the applied voltage was analysed by current–voltage (I-V) measurements. These results suggest that the prepared composite can proficiently serve as a reliable choice for the electrode material for high-performance supercapacitor applications.

Boron-incorporated Sulfonated polysulfone/polyphosphoric acid electrolytes for supercapacitor application

ABSTRACTIn the present work, boron-doped multicomponent gel polymer electrolytes composed of host polymer, sulfonated polysulfone (SPSU) and the additives; ionic liquid, 1-ethyl-3-methyl-imidazolium tetrafluoroborate (IL), H3BO3, polyphosphoric acid (PPA) were prepared. Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) techniques were used to characterize the sulfonated polysulfone-based electrolytes. Ion conductivity of these gel electrolytes were studied by dielectric impedance analyzer within the temperature from −20 to 100°C. The ionic conductivity of the SPSU-5IL-1PPA and SPSU-5IL-1H3BO3-1PPA were measured as 4.8 × 10−3 and 9 × 10−4 S cm−1, respectively. Supercapacitor having activated carbon-based composite electrode and electrolyte was constructed with the configuration: Al/C/electrolyte/C/Al. The electrochemical properties and ion transfer characteristics of the supercapacitor were investigated by the cyclic voltammetry (CV). Galvanostatic charge—discharge experiments exhibited good electrochemical reversibility and produced a specific capacitance value of 120 F g−1 at 1 A g−1. The symmetric supercapacitor system was retained almost 85% of its initial activity after 1000 cycle.

Evaluation of nitrogen- and sulfur-doped porous carbon textiles as electrode materials for flexible supercapacitors

With an objective to increase an electrochemical performance, simple and effective modifications of activated carbon fiber textiles (ACT) were carried out prior to their testing as supercapacitors. The modifications included a high-temperature treatment of the textile impregnated with N- and S-containing species (i.e. dicyandiamide, urea and thiourea). This led to an improvement in an electrical conductivity and in an enhanced mechanical strength with a preserved porosity. Compared to the performance of the initial unmodified carbon textile, a urea-functionalized material showed an enhancement in the electrochemical capacitance. An increase from 177 to 209 F g−1 at a scan rate 10 mV s−1 in an alkaline electrolyte was recorded (3-cell CV measurements) and from 138 to 166 F g−1 at 0.10 A g−1 (2-cell galvanostatic charge-discharge). The results suggested that mechanically stable, flexible and conductive ACT have a potential to be used in textile-based flexible supercapacitors. Benefits coming from the applied modification routes can be also adapted for the fabrication of other types of carbon-based composite electrode materials.

A comprehensive review on recently developed carbon based nanocomposites for capacitive deionization: From theory to practice

Abstract A comprehensive review through few decades of capacitive deionization (CDI) ever since discovery of Carbon aerogel, including a brief theory and factors influencing along with detailed focus on various electrode materials explored till now is done. The importance of suitable pore structure, high surface area, good wettability, high conductivity and quantitatively adsorb ionic components are discussed for optimal desalination performance. Specifically, porous carbon bassed materials are extensively explored as electrode materials in CDI setup, attributable to their availability, low cost and stability. This review mainly discusses the current state of the art in carbon based materials for enhanced desalination performance. Also, in this review, various carbon-based composite electrode materials, including porous carbon, porous carbon–metal oxide, carbon–polymer and carbon–polymer–metal oxide nanocomposites, are systematically investigated. Moreover, a brief outlook on the challenges and new research directions in the CDI area is also presented for researchers toward designing the high performance carbon based CDI device.

Redox-Active Organic Electrodes for Pseudocapacitor Applications

Current lithium-ion battery technology depends on inorganic cathode materials, such as LiCoO2 and LiFePO4. However, large-scale energy storage applications, including renewable energy storage and load-leveling, require more sustainable and cost-effective electrode materials. Organic electrode materials have been studied owing to their potential advantages, including the use of earth-abundant sources, environmental friendliness, and high energy density.1 We also have been investigating various redox-active organic electrodes by utilizing dopamine,1 pyrene derivatives,2 and glucose.3 Here, we further investigate the charge storage properties of the biomass-derived carbonaceous materials with Li- and Na-ions. We reveal that the synthesized carbonaceous materials can exhibit high capacities over 180 mAh/g in both Li- and Na-ions by based on double layer capacitance and redox reactions. These carbonaceous materials can be fabricated as the composite electrodes by mixing with conductive nanocarbons, including carbon nanotubes or reduced graphene oxides. These carbon-based composite electrodes show a high rate-capability and remarkable cycling stability. These high-performance organic electrodes could be promising candidates for developing large-scale energy storage devices.

Review on carbon-based electrode materials for application in capacitive deionization process

Most of the electrochemical studies related to porous carbon electrodes are those which can be used for either electrostatic energy storage or for energy conversion [using electrical double layer capacitor (EDLC)]. The techniques, such as electrodialysis, membrane filtration, advanced oxidation process, thermal evaporation, can be used now-a-days to treat salty water. Among which, capacitive deionization (CDI) has emerged as a novel cost effective and environment friendly desalination technology. CDI process involves the removal of inorganic ions from the salty water by applying an electrical potential between two porous carbon electrodes. Because of the passage of electrical potentials in the system, the unwanted ions present in the water sample will be adsorbed on the electrode surfaces. Hence, the electrodes which are having high surface area can exhibit higher desalination capacity. In this article, the application of various carbon-based composite electrode materials such as activated carbon and PVDF composite, carbon–metal oxide composite, carbon–CNT composite, carbon–polymer composite and carbon sheet (carbon aerogel, activated carbon cloth) in CDI process is systematically reviewed and presented. CDI process is being developed now-a-days especially toward commercialization in treating the brackish water.

Review on carbon-based composite materials for capacitive deionization

Carbon-based composite electrode materials, including carbon–carbon, carbon–metal oxide, carbon–polymer and carbon–polymer–metal oxide for efficient capacitive deionization are summarized.

High-performance supercapacitors based on freestanding carbon-based composite paper electrodes

Using a simple filtration method, we fabricate freestanding carbon-based composite paper electrodes (F-CCPEs), based on acid-treated carbon nanotubes (a-CNTs) and microporous carbon-based nanoplates containing numerous heteroatoms (H-CMNs). The F-CCPEs exhibited a high electrical conductivity of 2.3 × 102 S cm−1 and a high surface area of 1211.7 m2 g−1; moreover, they had numerous electroative heteroatoms and showed mechanical flexibility. Therefore, F-CCPEs without current collectors and binder show a superior electrochemical performance. In particular, the prepared F-CCPEs exhibit high capacitances of 275 and 148 F g−1 in aqueous and organic electrolytes, respectively. In addition, the specific energy density and specific power density of these F-CCPEs were found to be 63 Wh kg−1 and 140 kW kg−1, respectively, with good cyclic stability, even after 20,000 charge/discharge cycles.

Dramatic Improvements in Electric Double-Layer Capacitors by Using Polysaccharides

A nonaqueous solid-state electrolyte based on an alginate (Alg) with a conventional supporting electrolyte was prepared for use in electric double layer capacitors (EDLCs). According to the charge/discharge measurements, despite the use of a solid-state electrolyte, the model EDLC cells containing the Alg-based electrolyte possessed a higher discharge capacitance than the corresponding solution-based electrolyte, which implies that the high affinity of Alg for activated carbon electrodes decreases the electrode/electrolyte interfacial resistance. Because of its good affinity for carbon materials, we also applied Alg as a binder to an activated carbon-based composite electrode. The test cells with the composite electrodes containing Alg demonstrated a remarkably powerful EDLC performance using both a conventional organic-solution-based electrolyte and a highly viscous ionic liquid electrolyte.

Effect of poly(3,4-ethylenedioxythiophene) (PEDOT) in carbon-based composite electrodes for electrochemical supercapacitors

Electrochemical double layer supercapacitor cells were fabricated and tested using composite electrodes of activated carbon with carbon black and poly(3,4-ethylenedioxythiophene) (PEDOT), and an organic electrolyte 1 M TEABF 4/PC solution. The effect of PEDOT on the performance of the EDLC cells was explored and the cells were characterised by electrochemical impedance spectroscopy (EIS), cyclic voltammetry and galvanostatic charge–discharge. A generalised equivalent circuit model was developed for which numerical simulations were performed to determine the properties and parameters of its components from the EIS data. It was found that the proposed model fitted successfully the data of all tested cells. PEDOT enhanced the electrode and cell capacitance via its pseudo-capacitance effect up to a maximum value for an optimum PEDOT loading and greatly increased the energy density of the cell while the maximum power density has been still maintained at supercapacitor levels. Furthermore, PEDOT replaced PVDF as a binder and harmful solvent release was reduced during electrode processing. Activated carbon–carbon black composite electrodes with PEDOT as binder were found to have specific capacitance superior to that of activated carbon–carbon black electrodes with PVDF binder.

Desalination performance of a carbon-based composite electrode

In order to enhance the desalination performance of carbon-based composite electrodes, an ion-exchange resin/carbon composite electrode was newly manufactured by mixing activated carbon powders, PTFE binder, and ion-exchange resins. The desalination performance of the electrode was greatly enhanced by about 35% due to enhancement of hydophilicity compared to that of a conductive carbon black/carbon composite electrode. It was also higher by about 14% than that of a carbon cloth electrode. The results suggest that the desalination performance of the electrode can be improved with the introduction of ion-exchange resins, and the resulting electrode is suitable for use in capacitive deionization.