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Hydroxyl terminated poly(dimethylsiloxane) (PDMS-HT) is used as an electrolyte additive in electrolyte systems containing 1 M LiPF6 in EC:DMC (ratios 1:9; 3:7; 4:6 and 1:1 v/v) to enhance the cycle performance of lithium-ion batteries. Adding a small amount of PDMS-HT to the standard LIB electrolyte leads to improved specific capacity as well as improved capacity retention over prolonged cycles. There is also a slight increase in Li+ ion conductivity when PDMS-HT is added. Also, the PDMS-HT additive allows the formation of a more stable solid electrolyte interface (SEI) layer that enables the LIB cells to be cycled for longer cycles with minimal capacity fading. This combination of improved ionic conductivity and stable SEI layer formation due to the PDMS-HT additive, makes it an excellent candidate for an electrolyte additive for lithium ion batteries.

In this study, the experiment was conducted assuming that the citrus fruits were contaminated with bacteria. Herein, orange peels (OP) and lemon peels (LP) can be used as a carbon source and have the advantage of using discarded materials and heteroatoms. Also, the nitrogen heteroatom is introduced by naturally doping the materials with bacteria (Escherichia Coli, E. coli). The as-prepared bacteria doped activated carbon showed an increase in nitrogen content and surface properties which led to an improvement in electrochemical properties. The specific capacitance of bacteria doped OP and LP was 92.4 and 139 F g−1 compared to the bare samples with a specific capacitance of 60.9 and 49.6 F g−1 at a current density of 0.2 A g−1 and capacity retention of 129% after 10,000 cycles for the bacteria-doped samples. This process which is simple, cheap, and environmentally friendly can be applied to discarded fruit peels for the fabrication of supercapacitor materials.

Zinc oxide (ZnO) nanostructures/bacteria (Escherichia coli, E. coli) composite material is successfully prepared via carbonization process. Morphological and electrochemical properties of nanostructure were studied as function of concentration of bacteria solution. Morphological properties of the composite material were investigated by scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET). The new approach of high-performance electrodes based on carbonization prepared from precursor and reductant of ZnO and bacteria resources. The ZnO nanostructures were reacted with the bacteria to introduce carbon (C) and nitrogen (N) for better electrochemical performance and an increased surface area. The bacteria doped ZnO electrode exhibited significantly enhanced specific capacitance (41 F g−1) at a discharge current density of 0.5 A g−1, and cycling stability of 55% retention after 5000 cycles. Therefore, the bacteria as electrical dopant gave higher specific capacitance and cycle stability to the other metal oxide which could be a potential candidate in commercial applications of supercapacitors.

Palm kernel shell and coconut shell are used as a precursor for the production of activated carbon, a way of mitigating the tons of waste produced in Ghana. The raw Palm kernel shell and coconut shell were activated chemically using H3PO4. A maximum activated carbon yield of 26.3 g was obtained for Palm kernel shell and 22.9 g for coconut shell at 400oC, an impregnation ratio of 1.2 and 1-hour carbonization time. Scanning electron microscopy reveals well-developed cavities of the H3PO4 activated coconut shell and Palm kernel shell compared to the non-activated carbon. Iodine number of 743.02 mg/g and 682.11 mg/g, a porosity of 0.31 and 0.49 and the electrical conductivity of 2010 μS/cm and 778 μS /cm were obtained for the AC prepared from the coconut shell and Palm kernel shell respectively. The results of this work show that high-quality activated carbon can be manufactured locally from coconut shell and Palm kernel shell waste, and a scale-up of this production will go a long way to reduce the tons of coconut shell and Palm kernel shell waste generated in the country.

The nano-biocomposite electrodes composed of carbon nanotube (CNT), polypyrrole (PPy), and

A novel zwitterionic lithium-benzotriazole sulfobetaine is fabricated by grafting 1,3– propanesultone onto benzotriazole and then lithiating it. The resultant lithium-benzotriazole-sulfobetaine additive is used as an electrolyte additive in lithium ion batteries in 1 M LiPF6 (ethylene carbonate/dimethyl carbonate = 1:1). The electrolytes with the lithium-benzotriazole sulfobetaine shows higher ionic conductivities (2.18 × 10−2 S cm−1) compared to the bare electrolyte (1.07 × 10−2 S cm−1) and greater electrochemical stability (anodic limit at ~5.5 V vs. Li/Li+) than the pure electrolyte (anodic limit at ~4.6 V vs. Li/Li+). The discharge capacity of the lithium cobalt oxide/graphite cells is improved at higher C-rates with the addition of lithium-benzotriazole sulfobetaine due to increased ionic conductivity. The lithium cobalt oxide/graphite cells with the lithium-benzotriazole sulfobetaine additive also show stable cycling performance. These findings warrant the use of lithium-benzotriazole sulfobetaine as an electrolyte additive in lithium ion batteries.

Carbon nanowall (CNW) and carbon nanotube (CNT) were prepared as anode materials of lithium-ion batteries. To fabricate a lithium-ion battery, copper (Cu) foil was cleaned using an ultrasonic cleaner in a solvent such as trichloroethylene (TCE) and used as a substrate. CNW and CNT were synthesized on Cu foil using plasma-enhanced chemical vapor deposition (PECVD) and water dispersion, respectively. CNW and CNT were used as anode materials for the lithium-ion battery, while lithium hexafluorophosphate (LiPF6) was used as an electrolyte to fabricate another lithium-ion battery. For the structural analysis of CNW and CNT, field emission scanning electron microscope (FE-SEM) and Raman spectroscopy analysis were performed. The Raman analysis showed that the carbon nanotube in composite material can compensate for the defects of the carbon nanowall. Cyclic voltammetry (CV) was employed for the electrochemical properties of lithium-ion batteries, fabricated by CNW and CNT, respectively. The specific capacity of CNW and CNT were calculated as 62.4 mAh/g and 49.54 mAh/g. The composite material with CNW and CNT having a specific capacity measured at 64.94 mAh/g, delivered the optimal performance.

A composite anode material is fabricated from mesoporous carbon and synthesized Li4Ti5O12 nanoflakes for application in lithium ion batteries. Li4Ti5O12 is used as a capacity contributing conductive additive because of the change in its electronic structure from insulating to metallic as it undergoes lithiation. Cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy are used to analyze the electrochemical properties of the mesporous carbon/Li4Ti5O12 nanoflakes composite material, and synergistic results have been confirmed. The composite achieves high specific capacity and excellent cyclability with a capacity stabilizing at 300 mA h g−1 after 100 cycles at a current density of 175 mA g−1 and 200 mA h g−1 after 500 more cycles at a high current density of 500 mA g−1. This research shows the applicability of using LTO as a conducting agent with significant capacity contribution as a composite material with anode materials discharged to 0.01 V for high energy storage with fast charge–discharge capability.

A novel approach of preparing high performance electrodes for supercapacitors was demonstrated by pyrolyzing the hierarchical composite prepared from organic waste and biological resources. Sponge waste was utilized as a carbon source for preparing the interconnected structured electrode materials with high porosity, and needle-like ZnO particles were directly grown on the sponge in order to effectively capture bacteria cells as well as improve the overall redox reactions. The bacteria (E. coli O157:H7) were isolated on a ZnO/sponge composite to endow electrochemically beneficial inherent nitrogen existing in bacteria, as well as to provide bio-templates with the aids of these structural and material benefits, the carbonized material prepared from the bacteria loaded on the ZnO/sponge composite showed a significantly enhanced specific capacitance of 133 F g−1 (at 0.2 A g−1) and an excellent cycle retention of 89% over long-term cycles (5000 cycles). Our strategy of utilizing recyclable and biomass-derived materials not only can effectively improve the electrochemical performances of supercapacitors but also open an innovative way to address the systemic issues underlying the carbonaceous materials used in supercapacitors.

A simple simultaneous complementary oil-water separation and water desalination system is designed using grafted glass fiber (GF) membranes. Non-fluorinated trialkoxysilanes are grafted to form superhydrophobic and superhydrophilic GF membranes, respectively. Zwitterion sulfobetaine was also synthesized and grafted on the glass fiber to make a superhydrophilic glass fiber membrane. The superwetting grafted GF membranes which are superhydrophobic had a water contact angle of 152° and high separation efficiency (>99%) for ten cycles and the superhydrophilic had an underwater oil contact angle of 156° and high separation efficiency (>98%) for ten cycles. The zwitterionic glass fiber membrane also exhibits excellent removal performance for heavy metal ions and nitrate ions from the water layer. This method is simple and scalable, and provides a versatile way for designing devices that achieve both oil/water separation and water desalination simultaneously.

This study aimed to apply annealing processes during the coating of photovoltaic (PV) module glasses to PV modules already installed through an easy and simple procedure. Three types of annealing treatments were applied to PV module glasses, i.e., furnace, rapid thermal annealing (RTA) and torch. Among these, torch annealing, which can be easily carried out at PV module installation sites, was applied to PV module glasses using different numbers of repetition. Light transmittance, contact angle, anti-pollution characteristics, adhesion and hardness of the functional coating films after using different annealing treatment times and methods were measured, and it was confirmed that these characteristics varied depending on the annealing treatment times and methods. Through this, it was possible to optimize the process conditions that provide excellent anti-pollution characteristics and could be easily utilized at on-site PV modules.

Electrochemical characterization was conducted on poly(vinyl alcohol) (PVA)-ceramic composite (PVA–CC) separators for supercapacitor applications. The PVA–CC separators were fabricated by mixing various ceramic particles including aluminum oxide (Al2O3), silicon dioxide (SiO2), and titanium dioxide (TiO2) into a PVA aqueous solution. These ceramic particles help to create amorphous regions in the crystalline structure of the polymer matrix to increase the ionic conductivity of PVA. Supercapacitors were assembled using PVA–CC separators with symmetric activated carbon electrodes and electrochemical characterization showed enhanced specific capacitance, rate capability, cycle life, and ionic conductivity. Supercapacitors using the PVA–TiO2 composite separator showed particularly good electrochemical performance with a 14.4% specific capacitance increase over supercapacitors using the bare PVA separator after 1000 cycles. With regards to safety, PVA becomes plasticized when immersed in 6 M KOH aqueous solution, thus there was no appreciable loss in tear resistance when the ceramic particles were added to PVA. Thus, the enhanced electrochemical properties can be attained without reduction in safety making the addition of ceramic nanoparticles to PVA separators a cost-effective strategy for increasing the ionic conductivity of separator materials for supercapacitor applications.

Physical mixing of activated carbon (AC) and a quinone derivative, 2,5-bis (pro-2-ny-1-ylamino) cyclohexa-2,5-diene-1,4-dione (coded HBU-281) was used to design a composite electrode for supercapacitors. The process proves to be simple and cost-effective; providing better performance compared to other reported methods. The electrode properties were probed in terms of composite composition, redox behavior, specific capacitance, and cycle life. The capacitance performance of the AC electrode was enhanced due to the extra redox reaction of hydroquinone/quinone couple of HBU-281. The composites recorded higher specific capacitance and excellent cycle stability than the individual electrodes (AC or HBU-281). This excellent performance can be connected to the synergistic contribution of AC facilitating the electron distribution of HBU-281, and making pronounce its redox activity. These findings led to the conclusion that physical mixing of AC and HBU-281 can be adopted to design cheap and excellent composite electrodes for supercapacitor applications.

Lithium sulfonyl silica (LSS) was synthesized by replacing the surface H group in fumed silica with (CH2)3SO3Li and adopted as electrolyte additive for lithium ion battery. 3 wt% of the synthesized particles in 1 M LiPF6 (EC/DMC = 1:1) showed improved ionic conductivity and better potential stability over the pristine electrolyte. The discharge capacity of the LiCoO2/graphite is particularly enhanced with the addition of LSS at higher C-rates due to the enhanced ionic conductivity at room temperature. The LiCoO2/graphite cells using 1.0 M LiPF6/EC/DMC (1: 1) and 1.0 M LiTFSI/EC/DMC (1: 1) with LSS also showed superior performance for the self-discharge test carried out at 45 °C for 200 days. These positive impacts of LSS on LiCoO2/graphite cells warrant its use in lithium ion batteries.

The application of lithium (Li) metal as an anodic electrode for potential use in Li batteries has of late attracted much attention. This is because of its higher theoretical energy capacity (3860 mAh g−1) and negative potential (−3.04 V vs. standard hydrogen electrode (SHE)). However, Li metal anode possesses its own problem and chief being the formation of Li dendrites. Acuminate Li dendrites can pierce through the polyolefin separator causing the battery to short and this can potentially lead to fire. To buttress this problem, we synthesized and applied rod-like zinc oxide (ZnO) nanoparticles as a coating material on separators for suppressed dendrite formation in Li metal batteries. The cells with the coated separator showed improved electrochemical performance with an 83.4% capacity retention compared to the pristine separator with 65.5% after 100 cycles. This was due to suppressed dendrite formation. These results show that rod-like ZnO nanoparticle is a potential candidate for use as a coating material for separators in Li metal batteries.

Supercapacitors provide us with enormous power output for energy storage. Their energy output however still remains quite low compared to other energy storage materials like the batteries. This paper reports a highly stable liquid electrolyte which is composed of mixtures of 1-ethyl-3-methylimidazolium tetrafluoroborate(EMIBF 4 ) ionic liquid with highly stable lithium bis(oxalate)borate LiBOB/acetonitrile(ACN). The electrolytes display remarkable supercapacitive performance at a high voltage of 3 V. The electrochemical impedance spectroscopy shows that EMIBF 4 helps to reduce the bulk resistance and charge transfer resistance across the electrode surfaces by facilitating high ionic diffusions across the electrode/electrolyte interface. The high stability and high ionic conductivity of the electrolytes reflected in the good cycling performance tests at 2.8 V with a maximum delivery capacitance of 19.5Fg -1 after 1000cycles at a high scan rate of 200 mVs -1 .

Liquid electrolyte consisting of 1 M LiPF 6 in ethylene carbonate (EC)/dimethyl carbonate (DMC) and 0.1 wt% benzotriazole (BzTz) is studied in LiCoO 2 //graphite battery system at room temperature. Benzotriazole addition introduces excellent electrochemical stability (5.6 V vs Li) and good ionic conductivity properties at room temperature. Also, this electrolyte shows good cycling performance and better discharge capacities at high C-rates relative to the pristine electrolyte. Furthermore, the additive allows the formation of a good solid electrolyte interphase (SEI) per cyclic voltammetry (CV) examination. These specialized properties make this liquid electrolyte ideal for high power and high voltage applications.

Carbon materials have enjoyed wide applications in supercapacitors because of their high surface area which guarantees a high power output through the formation of an electric double layer (EDL). However the energy stored by this EDL mechanism is often insufficient and as such there is the need to upgrade them for higher energy applications. Quinone materials are attracting interest because of their pseudocapacitance contributions which help to boost the energy density of supercapacitors. In this study, composite supercapacitor electrodes are prepared by mechanically mixing 2,3,5,6-tetrachloro-1,4-benzoquinone (TCBQ) and activated carbon. An investigation of 5% w/w and 10% w/w of this quinolic material as a pseudocapacitance material to activated carbon in 1 M HCl aqueous electrolyte delivers a specific capacitance of 236 F g −1 and 240 F g −1 comparable to 190 F g −1 of just activated carbon over a potential range of −0.3 V–0.9 V vs Ag + /Ag. Contrary to what is commonly observed, this material is highly insoluble in the electrolyte medium and remains stable with cycling, recovering 99.57% (for 10% w/w addition) and 99.13% (for 5% w/w addition) of its initial capacitance after cycling at 500 mV s −1 scan rate. The findings in this report potentially provides a cheaper yet efficient route to boost the energy density of activated carbon using TCBQ for high energy supercapacitor applications.

Zwitterionic lithium-silica sulfobetaine silane (Li-SiSB) is fabricated and used as an additive together with hydroxyl–terminated poly(dimethylsiloxane) (PDMS-HT) for use as low temperature additives in lithium ion batteries (LIB). The additives dissolved in 1 M LiPF6 (ethylene carbonate/dimethyl carbonate = 1:1). The electrolyte containing Li-SiSB and PDMS-HT shows higher ionic conductivity (1.54 × 10 - 3 Scm−1 at −20 °C). Full cells show enhanced specific capacity at higher C-rates in the presents of additives due to anti–freezing and enhanced ionic conductivity. The also enhance early, stable and dense SEI which in turn leads to improved cycling stability. These results merit the use of both Li-SiSB and PDMS-HT as electrolyte additives for improved low temperature performance in lithium-ion batteries.

The electrical properties of silicone composite films filled with silver (Ag) nanoparticle-decorated multi-walled carbon nanotubes (MWNT) prepared by solution processing are investigated. Pristine MWNT is oxidized and converted to the acyl chloride-functionalized MWNT using thionyl chloride, which is subsequently reacted with amine-terminated poly(dimethylsiloxane) (APDMS). Thereafter, APDMS-modified MWNT are decorated with Ag nanoparticles and then reacted with a poly(dimethylsiloxane) solution to form Ag-decorated MWNT silicone (Ag-decorated MWNT-APDMS/Silicone) composite. The morphological differences of the silicone composites containing Ag-decorated MWNT and APDMS-modified MWNT are observed by transmission electron microscopy (TEM) and the surface conductivities are measured by the four-probe method. Ag-decorated MWNT-APDMS/Silicone composite films show higher surface electrical conductivity than MWNT/silicone composite films. This shows that the electrical properties of Ag-decorated MWNT-APDMS/silicone composite films can be improved by the surface modification of MWNT with APDMS and Ag nanoparticles, thereby expanding their applications.

We report the electropolymerization of phytic acid (PA) doped polypyrrole (PPy) thin film for supercapacitor application. The surface morphology and presence of various functional groups in PA doped PPy films were analyzed using scanning electron microscopy, FTIR and Raman spectroscopy. The electrochemical properties and supercapacitor behavior of the PA/PPy thin films were performed using cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge/discharge techniques in 1 M H2SO4 electrolyte. The effect of various experimental conditions such as concentration of pyrrole monomer, phytic acid and deposition time have been studied to affirm the optimized electropolymerization of PA doped PPy thin film. Among these, 0.1 M PA doped 0.6 M of pyrrole thin film deposited on stainless steel (SS) substrate for 10 min exhibited a maximum specific capacitance of 297 Fg−1 and energy density 41.25 Whkg−1 at 5 mVs−1 scan rate. In addition, the same optimum condition have been extended for electropolymerization of PA/PPy thin film on titanium (Ti) substrate and achieved a maximum specific capacitance of 343 Fg−1 with high energy density 47.64 Whkg−1 at 5 mVs−1 scan rate. Moreover, SS and Ti substrate coated PA/PPy electrodes show high charge/discharge efficiency at 10 Ag−1 current density with ∼91% and 77% of specific capacitance retention after 4000 cycles, which indicates good electrochemical reversibility and cycling stability of the fabricated electrodes.

The capacitances of partially oxidized multi-walled carbon nanotubes (MWNTs) electrodes treated with nitric acid were investigated for use as the electrode materials of electric double-layer capacitors (EDLCs). The oxidized MWNTs had a much higher specific surface area, pore volume and average pore width than those of pristine MWNTs. Moreover, functional groups such as hydroxyl, carbonyl and carboxyl groups were observed on the surfaces of oxidized MWNTs. The specific capacitance of the oxidized MWNTs after 3 h a nitric acid treatment was 68.8 F/g in the highest oxidized state, more than 7 times greater than that of the pristine MWNTs. Further, the capacitance trends apparently follow the change of the zeta potentials, not the surface areas, indicating that this trend depends on the adsorption of electrolytes as compared to the migration path structure. Further, the oxidized MWNT electrode materials showed good long-term stability during repeated cycles and no decay for more than 1000 cycles.

Two 1,4-dihydoxynaphthalene (PhQH 2 )-based derivatives (coded as HBU-551 and HBU-552) are synthesized by reacting with different amines (i.e., tryptamine and phenethylamine, respectively) to use as organic additives of activated carbon supercapacitors. The composite electrodes with HBU-551 and HBU-552 are also prepared by blending with the ratio of 70:25 w/w, and their supercapacitive properties are investigated in terms of redox behaviors and specific capacitance evolutions against scan rate and cycle life. The organic additives and their composites with activated carbon are dominantly characterized by PhQ-PhQH 2 redox transition accompanying a two-electron two-proton process, and weakly affected by reversible redox reaction of nitrogen in the NH group, which involves an additional one-electron one-proton process. Thus, the composite electrodes show higher specific capacitance over 210 F g −1 due to the synergistic effect between activated carbon (pseudocapacitance) and organic additives (redox behavior). Cycle performance and high-rate capability can also be enhanced by the adoption of PhQH 2 -based organic additives for their pore-filling morphology to increase the packing density of composite electrodes.

A lithium-modified silica nanosalt (Li–SiO 2 , coded Li202) of hydrophobic fumed silica (R202) is synthesized to use as an electrolyte additive for lithium-ion batteries (LIBs) under low temperature conditions. The synthesis method consists of reacting the silica nanoparticles with LiH and consequently quickly reacting the conjugate silicate ions with 1,3-propanesultone as a surface stabilizer. The obtained Li202 nanosalt (2.5 wt%) is added into an electrolyte solution of 1.0 M LiPF 6 dissolved in ethylene carbonate/propylene carbonate/ethylmethyl carbonate/diethyl carbonate (20:5:55:20 vol%) + 2 wt% vinylene carbonate. The electrolyte solution including the Li202 nanosalt shows higher ionic conductivity and superior electrochemical stability over 5 V, which is due to the stabilized surface group. The high-rate capability at −20 °C of the LiCoO 2 /graphite cell is particularly enhanced by adding Li202 nanosalt. In addition, excellent cycle performance at −20 °C endorses the use of Li202 nanosalt as a low-temperature electrolyte additive for LIBs.

A hydrogel electrolyte consisting of 6 M KOH aqueous solution, potassium polyacrylate (PAAK, 3 wt.%), and a hydrophilic silica OX50 (1 wt.%) was prepared to use as an electrolyte medium coated on a Scimat separator of activated carbon supercapacitor. The silica particle distributed homogeneously on surface pores of the separator to increase ionic conductivity and electrochemical stability of the hydrogel electrolyte. The silica addition also involved superior specific capacitance even at higher scan rates due to decrease in interfacial resistance between hydrogel elec- trolyte and activated carbon electrode.

In this work, poly[dimethylsiloxane- co -(siloxane- g -acrylate)] (PDMS-A) and lithium-modified silica nanosalt (Li202) are used together as low-temperature electrolyte additives in lithium-ion batteries (LIBs), taking advantage of the electrochemical and interfacial stabilities due to their surface functional groups. Using these additives together improves the electrochemical stability and ionic conductivity of liquid electrolyte solution to over 5.5 V and 4 × 10 −4 S cm −1 at −20 °C, respectively. The room-temperature electrochemical performance of a conventional LIB (LiCoO 2 /graphite) is improved by the addition (e.g., initial discharge capacity of 95.9 mAh g −1 obtained after charging at 1.0 C -rate and consequent discharging at 5.0 C -rate). The low-temperature performance is also enhanced, achieving a capacity retention ratio of 63.4% after 50 cycles at −20 °C, compared to 38.7% without the additives. It is also notable that the PDMS unit commonly existing in both additives may be the main cause of the synergistic effects on the electrochemical performance due to the compatibility between PDMS-A and Li202.

© 2016 ETRI Journal, Volume 38, Number 2, April 2016 http://dx.doi.org/10.4218/etrij.16.2515.0018 Di(1-aminopyrene)quinone (DAQ) as a quinonecontaining conducting additive is synthesized from a solution reaction of 1-aminopyrene and hydroquinone. To utilize the conductive property of DAQ and its compatibility with activated carbon, a composite electrode for a supercapacitor is also prepared by blending activated carbon and DAQ (3:1 w/w), and its supercapacitive properties are characterized based on the cyclic voltammetry and galvanostatic charge/discharge. As a result, the composite electrode adopting DAQ exhibits superior electrochemical properties, such as a higher specific capacitance of up to 160 F·g at 100 mV·s, an excellent high-rate capability of up to 1,000 mV·s, and a higher cycling stability with a capacitance retention ratio of 82% for the 1,000th cycle.

Layered electrodes of electrodeposited RuO 2 (eRuO 2 ) and polyaniline (ePAn) are prepared on a platinum substrate to yield ePAn-on-eRuO 2 and eRuO 2 -on-ePAn electrodes and their supercapacitive properties are investigated. The eRuO 2 electrode forms a compact stratified structure with nearly flat surfaces by electrodeposition from a RuCl 3 ·3H 2 O-based solution, whereas the ePAn electrode forms densely connected particles or particle aggregates by the electrodeposition from aniline solution. In the scan rate range of 20–1000 mV s −1 , specific capacitance (810–575 F g −1 ) of ePAn-on-eRuO 2 electrode is superior by the higher probability to occur redox reaction and proton diffusion due to particulate surface and inner pores of the upper layer (ePAn), respectively. In contrast, the eRuO 2 -on-ePAn electrode loses the specific capacity (680–550 F g −1 ) but achieves higher capacity retention ratio (81%) by flat compact surface of the upper layer (eRuO 2 ).

To enhance the electrochemical performance, a conventional activated carbon supercapacitor is modified by adopting potassium-polyacrylate (PAAK) electrolyte additive on a glass fiber separator and by fabricating the activated carbon electrode on nickel foam instead of on conventional nickel foil as a current collector. The glass fiber separator plays the role of self-supporting PAAK-KOH hydrogel electrolyte with superior ionic conductivity. Moreover, the adoption of nickel foam strengthens the close contact between the active material and the current collector, reducing the interfacial resistance between electrode and electrolyte. As a result, the combination of glass fiber separator and nickel foam substrate can contribute to a great increase in the specific capacitance, to a value of over 200 F g−1, and to an enhancement of the high-rate capability of activated carbon supercapacitors.

This study constitutes the first attempt to use an OLED emitter material as a novel supercapacitor component. In supercapacitor tests, the specific capacitance (33.07 F g−1) of a poly(9-(3-vinyl-phenyl)-anthracene) (PVPA)/multi-walled carbon nanotube (MWCNT) mixture was found to be approximately three times that of the system composed of the MWCNTs alone.

Bacteria-loaded polyaniline@multi-walled carbon nanotubes (MWNTs) composite materials were prepared, and their electrochemical properties were investigated for application in supercapacitor electrodes. The polyaniline@MWNTs composite were synthesized through in situ polymerization of polyaniline in MWNTs dispersion. Then, two types of bacteria (Gram-positive and Gram-negative bacteria) were loaded on the polyaniline@MWNTs composite and carbonized to produce bacteria-loaded composite electrodes. Bacteria were first attached to the composites through electrostatic interaction and porous morphology, then doped after the carbonization process. The composites showed different electrochemical properties depending on the type of bacteria applied, and exhibited increased specific capacitance regardless of bacteria type. Bacteria-loaded materials, which exhibited a maximum specific capacitance value of 57.7 F g−1 at 0.2 A g−1 within a potential window of -1 – 0 V, achieved an increment of 60%, and this was maintained up to 70% after 1000 charging/discharging cycles.

A polyelectrolyte was made by combining poly (2-acrylamido-2-methylpropane sulfonic acid) (PAMPS) and silica–sulfobetaine silane (SiSB) zwitterion (ZW) for use in supercapacitors. The polyelectrolyte blend with 10 wt% SiSB applied for symmetric cells indicated a specific capacitance of 321 F g−1 at 10 mV s−1 which is almost two times larger than that of pure PAMPS. The electrolytes consisting of SiSB also showed higher ionic conductivity than that of pristine PAMPS electrolyte due to ionic channels generated the zwitterions, thereby accelerating ion activity in the electrolyte. The PAMPS with 10 wt% SiSB exhibited an excellent cycling stability of ~ 100% capacity retention over 5000 cycles compared to PAMPS with 73% retention. These results indicated a synergy effect via the silica-based zwitterion and the PAMPS which could be a prospective candidate for supercapacitors applications.

In this study, we synthesized bacteria-doped graphene oxide by one-pot carbonization process for supercapacitor electrodes. Bacteria solution depending on the type of Gram-negative and -positive bacteria were mixed with graphene oxide (GO), then carbonized at 700 °C for 1 h. The electrochemical properties demonstrated superior electrochemical performance as supercapacitors electrode application. The specific capacitance of prepared electrode was 237 F g−1 at the current density of 0.5 A g−1, which was more than 5 times greater than that of the graphene oxide and good cycling stability with no decay after 5000 cycles. These attractive results suggest that graphene oxide/bacteria composites can be used a supercapacitor electrodes material with high-performance.