OVER THE PAST FEW YEARS, CONSIDERABLE EFFORT HAS BEEN DEVOTED TO THE DEVELOPMENT OF ALTERNATIVE ENERGY STORAGE/CONVERSION DEVICES WITH HIGH POWER AND ENERGY DENSITIES BECAUSE OF THE EVERINCREASING ENVIRONMENTAL PROBLEMS AND THE UP-COMING DEPLETION OF FOSSIL FUELS. supercapacitorS HAVE ATTRACTED A GREAT DEAL OF ATTENTION OWING TO THEIR HIGHER POWER DENSITIES RELATIVE TO SECONDARY BATTERIES AND TRADITIONAL ELECTRIC DOUBLE-LAYER CAPACITORS [1-3]. GRAPHENE AND MULTIWALLED CARBON NANOTUBES (MWCNTS) HAVE ENJOYED SIGNIFICANT RECENT ATTENTION. [2].HEREIN WE REPORT PHYSICAL MIXING/DISPERSION METHOD FOR PREPARING THE ELECTROACTIVE MATERIAL FOR supercapacitor ELECTRODE. GO WAS PREPARED BY HUMMER’S METHOD [4] AND DISPERSED IN DISTILLED WATER AND THEN MWCNTS WERE ADDED TO IT BY ULTRASONICATION FOR 0.5H. THE SPECIFIC CAPACITANCE OF GO-MWCNTS FROM THE CYCLIC VOLTAMMETRY (CV) CURVES OF FIGURE (1) WAS FOUND TO BE 256 MF. CM-2 AT SCAN RATE OF 10 MV.S-1 THAT WAS GREATER THAN OF 12 MF.CM-2 OBTAINED FOR MWCNT BY HONDA, ET AL [5]. MWCNTS TEND TO AGGLOMERATE WHILE SUSPENDED IN WATER, AND SURFACTANTS ARE NEEDED FOR UNIFORM DISPERSION. THE HIGH DISPERSIBILITY OF GRAPHENE OXIDE (GO) IN WATER AND ITS Π-Π INTERACTION WITH MWCNTS FACILITATES THE DISPERSION OF MWCNTS WITHOUT USE OF SURFACTANT [6].HIGH SPECIFIC SURFACE AREA OF GO AND MWCNTS AND SURFACE FUNCTIONALIZATION CAN CAUSE AN IMPROVEMENT IN THE SPECIFIC CAPACITANCE OF CARBON MATERIALS.

supercapacitorS AS ONE OF THE ALTERNATIVE ENERGY STORAGE/CONVERSION SYSTEMS HAVE ATTRACTED GREAT INTEREST IN RECENT YEARS. THESE SYSTEMS BENEFIT FROM HIGH POWER DENSITIES AND LONG CYCLE LIFE. MANY METAL OXIDE THIN FILM ELECTRODES HAVE BEEN INVESTIGATED AS supercapacitorS AND SHOWED GOOD CAPACITANCES ORIGINATED FROM THEIR REDOX TRANSITIONS. HOWEVER, THE LOW CONDUCTIVITY OF THESE OXIDES IS THE MAIN DISADVANTAGE WHICH MOTIVATES FURTHER RESEARCH IN THIS FIELD. ONE OF THE WAYS FOR OVERCOMING THIS DISADVANTAGE IS UTILIZING COMBINED ELECTRODE MATERIALS OF METAL OXIDES. SEVERAL BIMETAL OXIDES HAVE BEEN USED AND SHOWED BETTER CAPACITIVE BEHAVIOR THAN CORRESPONDING METAL OXIDES. IN THE PRESENT STUDY, NICKEL MANGANESE OXIDE HAS BEEN PREPARED BY COPRECIPITATION METHOD. THE PREPARED SAMPLE HAS BEEN CHARACTERIZED USING XRD TECHNIQUE, REVEALING THE ILMENITE PHASE (NIMNO3). ACTIVE MATERIAL WAS MIXED WITH DIFFERENT GRAPHITIC MATERIALS. BASED ON THE OBTAINED RESULTS, GRAPHITE SHOWED MORE WORKING POTENTIAL RANGE AND HIGHER CURRENT DENSITIES THAN OTHER SAMPLES. ELECTRODES WERE FABRICATED BY SPRAYING THE SUSPENDED MATERIALS TO NICKEL GRID AS THE SUBSTRATE. THE ELECTROCHEMICAL SUPERCAPACITIVE BEHAVIOR OF THE MATERIALS HAS BEEN INVESTIGATED USING CYCLIC VOLTAMMETRY AND GALVANOSTATIC CHARGE-DISCHARGE METHODS. IT WAS FOUND THAT THE MIXED NIMNO3/GRAPHITE (0.5:0.5) SAMPLE HAS THE HIGHEST CAPACITANCE COMPARED TO OTHER ELECTRODES. NIMNO3/GRAPHITE BASED supercapacitorS HAVE SHOWED SPECIFIC CAPACITANCE OF 54 F.G-1 AT DISCHARGE CURRENT DENSITY OF 0.1 A.G-1.

WITH DEVELOPMENT OF PORTABLE ELECTRONICS, DEMANDS FOR LOW COST, AND HIGH PERFORMANCE ENERGY STORAGE DEVICES WITH ENHANCED ENERGY/POWER DENSITY HAVE INCREASED. BECAUSE OF INTRIGUING FEATURES, supercapacitorS HAVE ATTRACTED GREAT INTERESTING TO COMPLEMENT OR REPLACE BATTERIES IN VARIOUS ELECTRONIC DEVICES. HEREIN, WE REPORT A HIGH PERFORMANCE supercapacitor BASED ON NANOPOROUS GRAPHENE/CUO COMPOSITE SYNTHESIZED WITH LOW COST HYDROTHERMAL METHOD. THE SYNERGIC EFFECTS OF GRAPHENE/CUO COMPOSITION WITH ITS NANOPOROUS STRUCTURE HAVE A KEY ROLE IN PROVIDING HIGHLY CONDUCTIVE SURFACE FOR UNIFORM GROWTH OF CUO NANOPARTICLES, FASTER ELECTRON TRANSFER, PREVENTION OF RESTACKING/AGGLOMERATION, SIMULTANEOUS EDLC AND PSEUDOCAPACITANCE CONTRIBUTION, FACILE MASS TRANSPORT AND LARGE ACCESSIBLE SURFACE AREA. THE NANOPOROUS GRAPHENE/CUO ELECTRODE EXHIBITS EXCELLENT ELECTROCHEMICAL PERFORMANCE INCLUDING A SPECIFIC CAPACITANCE OF 575 F G-1 AT 1 A G-1 AND 82% RETENTION AT AN ULTRAFAST RATE OF 50 A G-1 AND EXCELLENT CYCLE LIFE (6% LOSS AFTER 5000 CYCLES).

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BY INCREASING DEMANDS FOR MICROSCALE ENERGY STORAGE SYSTEMS USING A METHOD WHICH IS SCALABLE AND NOT CUMBERSOME IS REALLY NEEDED. IN THIS WORK WE HAVE PREPARED AN INTERDIGITATED MICROsupercapacitor USING THE LASER IN LIGHTSCRIBE DVD WRITERS...

ELECTROCHEMICAL CAPACITORS (ECS), ALSO CALLED supercapacitorS OR ULTRACAPACITORS, HAVE RAISED CONSIDERABLE ATTENTION OVER THE PAST DECADES BECAUSE OF THEIR HIGHER POWER DENSITY AND LONGER CYCLE LIFE THAN ECONDARY BATTERIES AND THEIR HIGHER ENERGY DENSITY COMPARED TO CONVENTIONAL ELECTRICAL CAPACITORS. VARIOUS MATERIALS SUCH AS TRANSITION METAL OXIDES, METAL HYDROXIDES AND POLYMERIC MATERIALS CAN BE USED IN ECS FOR INCREASED OF THEIRS ENERGY DENSITIES, THIS TYPE OF ELECTRICAL STORAGE DEVICES SO CALLED PSEUDOCAPACITORS. NI(OH)2 IS AN ATTRACTIVE PSEUDOCAPACITIVE MATERIAL BECAUSE OF ITS LOW COST, HIGH SPECIFIC CAPACITANCE AND HIGH ENERGY DENSITIES, AND WELL-DEFINED ELECTROCHEMICAL REDOX ACTIVITY. WE PREPARED NI(OH)2 BY ELECTRODEPOSITION METHOD FROM AN AQUEOUS SOLUTION OF NI(NO3)2 AT 25OC ON A COPPER SUBSTRATE WITH GEOMETRIC AREA OF 0.8 CM2. THIS ELECTRODE WAS USED AS THE WORKING ELECTRODE, AND TOO, SATURATED CALOMEL ELECTRODE WAS USED AS REFERENCE AND A PT DISC WITH AREA OF 5 CM2 AS A COUNTER. THE ELECTROCHEMICAL PERFORMANCES ARE INVESTIGATED BY CYCLIC VOLTAMMETRY (CV) AND GALVANOSTATIC CHARGE-DISCHARGE TECHNIQUES IN 1 M KOH SOLUTION AT 25OC. THE STRUCTURE AND MORPHOLOGY OF PRODUCTS WERE CHARACTERIZED USING X-RAY DIFFRACTION (XRD) AND SCANNING ELECTRON MICROSCOPY (SEM). THE RESULTS SHOWED THAT THE NI(OH)2 WITH PARTICLE-LIKE MORPHOLOGY HAS EXCELLENT ELECTROCHEMICAL PERFORMANCES AND ITS SPECIFIC CAPACITANCE VALUE AS SINGLE ELECTRODE.

A supercapacitor IS A CHARGE STORAGE DEVICE BETWEEN THE ELECTROSTATIC CAPACITOR AND THE RECHARGEABLE BATTERY. IT HAS BEEN USED AS AN ENERGY STORAGE SYSTEM FOR PORTABLE ELECTRONIC DEVICES, BACKUP POWER SOURCES, AND HYBRID ELECTRIC VEHICLES [1-6]. CARBON MATERIALS, CONDUCTING POLYMERS AND TRANSITION METAL OXIDES, SUCH AS HYDROUS RUO2 AND MNO2 HAVE BEEN IDENTIFIED AS POSSIBLE ELECTRODE MATERIALS [7-10]. IN THE PRESENT STUDY THE MANGANESE OXIDE AND POLYANILINE (PANI) WAS CHEMICALLY DEPOSITED ON CARBON BLACK (CB) ELECTRODE. THE CAPACITANCE AND STABILITY OF THIS COMPOSITE FILM WERE INVESTIGATED BY CYCLIC VOLTAMMETRY (CV). THE REDOX PROPERTIES OF THE PANI-MNO2/CB EXHIBITED IDEAL CAPACITIVE BEHAVIOR IN A 0.5 M NA2SO4 SOLUTION. THE CAPACITANCE OF PANI-MNO2/CB CAN REACH 179.8 F G-1 AND MAINTAINS ABOUT 91% OF THE INITIAL CAPACITANCE AFTER 100 CYCLES. THIS INDICATES THAT THE IMPROVED ELECTROCHEMICAL PERFORMANCE OF PANI-MNO2/ CB IS DUE TO THE ENHANCED ELECTRICAL PROPERTIES BY MNO2 AND PANI COATING ONTO CB.