Carbon Nanofiber Anodes Research Articles

High power direct methanol fuel cell with a porous carbon nanofiber anode layer

Three anode electrodes containing Pt–Ru Black as a catalyst were fabricated with a porous layer made with different carbon materials: carbon black (CB), carbon nanofiber (CNF) and a combination of both carbon materials (CB+CNF). The carbon-based porous layer was coated onto a carbon cloth with PTFE pre-treatment for delivering hydrophobic properties and applied in direct methanol fuel cells (DMFCs). Characterisation of electrochemical properties for three different anode electrodes was performed with cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) at room temperature in a half-cell configuration. The evolution of the surface morphology of diffusion layer and electrodes was characterised by using variable-pressure scanning electron microscopy (VP-SEM). The electrochemical results indicate that electrode with CNF layer showed the highest current densities compared to CB and CB+CNF with the same catalyst loading. VP-SEM measurements show the network formation within the structure, which could facilitate the methanol mass transfer and improve the catalyst efficiency. The electrodes were applied to a single-cell DMFC, and the cell performance was experimentally investigated under passive operating mode and room temperature. A maximum power density of 23.0mWcm−2 at a current density of 88.0mAcm−2 with a 3M dilute methanol solution was achieved. The results show that the electrodes with a CNF layer could improve the performance of DMFC as compared with commercially used CB and prove it’s potentially application in DMFC technology especially for portable power source applications due to several advantages as followings: operating at low concentration of methanol, operating at room temperature, low catalyst loading in anode and cathode, cheaper, less hazardous and no parasitic load.

Improvement of cyclability of silicon-containing carbon nanofiber anodes for lithium-ion batteries by employing succinic anhydride as an electrolyte additive

Si/C composite nanofibers were prepared by electrospinning and carbonization using polyacrylonitrile as the spinning medium and carbon precursor. The effect of electrolyte additive succinic anhydride (SA) on the electrochemical performance of Si/C composite nanofiber anodes was investigated. Results show that after 50 cycles, the discharge capacity of Si/C composite nanofiber anode with the SA-added electrolyte is 34 % higher than that with additive-free electrolyte. At 150th cycle, the capacity retention of Si/C composite nanofiber anode with SA-added electrolyte is 82 % under 70 % state-of-charge. It is demonstrated that adding additive SA in the electrolyte is an effective and economic way to improve the cyclability of high-capacity Si/C composite nanofibers for next-generation high-energy lithium-ion batteries.

Activated carbon nanofiber anodes for microbial fuel cells

This investigation considers the use of activated carbon nanofiber nonwoven (ACNFN) as a novel anode for microbial fuel cells (MFCs). ACNFN has an ultra-thin, porous interconnected structure with high bioaccessible surface area. Reduced distances from the free surface to the interior maximize use of the available surface area and this, combined with high macroporosity ensures superior performance by decreasing transport limitations. ACNFN was fabricated by pyrolysis of electrospun polyacrylonitrile and subsequent steam activation. Extensive characterization, including surface morphology, material chemistry, surface area, mechanical strength and biofilm adhesion was performed to validate the use of the material as an MFC anode. Preliminary tests in a single chamber MFC showed current densities of 2715A/m3 which is about 10% greater than the highest maximum obtained so far. Further, this was achieved with a conductivity of only a fifth of that of the corresponding material. The bio-electrochemical performance of ACNFN was also compared to that of commonly-used anodes, carbon cloth and granular activated carbon. Such anode architecture will greatly help mitigate low power density issues which are one of the main factors limiting widespread adoption of MFCs.

Wastewater Treatment using Activated Carbon Nanofiber Anode Microbial Fuel Cells (MFCs)

Wastewater Treatment using Activated Carbon Nanofiber Anode Microbial Fuel Cells (MFCs)Microbial fuel cell (MFC) technology is a pioneering bio-electrochemical system (BES) exploiting anaerobic bacteria to harvest useful energy from various organic substrates in wastewater. Commercial anode's of significance for MFC applications are carbon based material (carbon cloth (CC), brush or graphite rod), which have been shown to have high internal...Author(s)Udayarka KarraSeetha S. ManickamJeffrey R. McCutcheonBaikun LiSourceProceedings of the Water Environment FederationDocument typeConference PaperPublisherWater Environment FederationPrint publication date Sep, 2012ISSN1938-6478DOI10.2175/193864712811709463Volume / Issue2012 / 10Content sourceWEFTECCopyright2012Word count210

Improvement of cyclic behavior of a ball-milled SiO and carbon nanofiber composite anode for lithium-ion batteries

The cyclic performance of a composite SiO and carbon nanofiber (CNF) anode was examined for lithium-ion batteries. SiO powder of several micrometers was pulverized using high energy mechanical milling. The SiO was ball-milled for 12 h with CNF to produce a composite electrode material that exhibited excellent cycling performance. A reversible capacity of approximately 700 mAh g −1 was observed after 200 cycles. The excellent cyclic performance was discussed with respect to the change of the valence state of Si by ball-milling. A large irreversible capacity at the first cycle for the SiO/CNF composite electrode was reduced to 2% by chemically pre-charging with a lithium film attached to the rim of the electrode.

Electrospun Carbon-Tin Oxide Composite Nanofibers for Use as Lithium Ion Battery Anodes

Composite carbon-tin oxide (C-SnO(2)) nanofibers are prepared by two methods and evaluated as anodes in lithium-ion battery half cells. Such an approach complements the long cycle life of carbon with the high lithium storage capacity of tin oxide. In addition, the high surface-to-volume ratio of the nanofibers improves the accessibility for lithium intercalation as compared to graphite-based anodes, while eliminating the need for binders or conductive additives. The composite nanofibrous anodes have first discharge capacities of 788 mAh g(-1) at 50 mA g(-1) current density, which are greater than pure carbon nanofiber anodes, as well as the theoretical capacity of graphite (372 mAh g(-1)), the traditional anode material. In the first protocol to fabricate the C-SnO(2) composites, tin sulfate is directly incorporated within polyacrylonitrile (PAN) nanofibers by electrospinning. During a thermal treatment the tin salt is converted to tin oxide and the polymer is carbonized, yielding carbon-SnO(2) nanofibers. In the second approach, we soak the nanofiber mats in tin sulfate solutions prior to the final thermal treatment, thereby loading the outer surfaces with SnO(2) nanoparticles and raising the tin content from 1.9 to 8.6 wt %. Energy-dispersive spectroscopy and X-ray diffraction analyses confirm the formation of conversion of tin sulfate to tin oxide. Furthermore, analysis with Raman spectroscopy reveals that the additional salt soak treatment from the second fabrication approach increases in the disorder of the carbon structure, as compared to the first approach. We also discuss the performance of our C-SnO(2) compared with its theoretical capacity and other nanofiber electrode composites previously reported in the literature.

Porous carbon nanofibers from electrospun polyacrylonitrile/SiO 2 composites as an energy storage material

Porous carbon nanofibers with large accessible surface areas and well-developed pore structures were prepared by electrospinning and subsequent thermal and chemical treatments. They were directly used as anodes in lithium-ion batteries without adding any non-active materials such as polymer binders or electronic conductors. The electrochemical performance results show that porous carbon nanofiber anodes have improved lithium-ion storage ability, enhanced charge–discharge kinetics, and better cyclic stability compared with non-porous counterparts. The unique structures and properties of these materials make them excellent candidates for use as anodes in high-performance rechargeable lithium-ion batteries.

Manganese oxide nanoparticle-loaded porous carbon nanofibers as anode materials for high-performance lithium-ion batteries

Mn-based oxide-loaded porous carbon nanofiber anodes, exhibiting large reversible capacity, excellent capacity retention, and good rate capability, are fabricated by carbonizing electrospun polymer/Mn(CH 3COO) 2 composite nanofibers without adding any polymer binder or electronic conductor. The excellent electrochemical performance of these organic/inorganic nanocomposites is a result of the unique combinative effects of nano-sized Mn-based oxides and carbon matrices as well as the highly-developed porous composite nanofiber structure, which make them promising anode candidates for high-performance rechargeable lithium-ion batteries.