Improved Electrode Materials Research Articles

Organometallic-Derived Carbon (ODC)-Metal Nano-Oxide Composites as Improved Electrode Materials for Supercapacitors.

In the search for the new generation of electrochemical energy storage materials, a novel and straightforward synthetic route for porous carbons and metal oxide nanoparticle composites based on the chlorination of the organometallic compounds Ni(C5H5)2 and Mn(C5H7O2)2 at moderate temperatures, followed by hydrothermal treatment, has been developed. Electrochemical measurements in a three-electrode configuration show that, in both composites NiO@ODC and Mn3O4@ODC, a synergistic effect between the capacitive and pseudocapacitive energy storage mechanisms is observed, thereby improving their electrochemical performance vs pure carbon materials. Electrochemical evaluation of symmetric cells gave gravimetric capacitances of 124 and 130 F g-1 for NiO@ODC and Mn3O4@ODC, respectively. However, the porous structure of the carbon matrix and the higher conductivity of Mn3O4, together, were found to be responsible for the superior electrochemical performance of Mn3O4@ODC.

Controlling Stability and Selectivity in the Competing Chlorine and Oxygen Evolution Reaction over Transition Metal Oxide Electrodes

AbstractChlor‐alkali electrolysis is a large‐scale industrial process, where the evolution of gaseous chlorine (chlorine evolution reaction, CER) at the anode is accompanied by a selectivity problem as the evolution of gaseous oxygen (oxygen evolution reaction, OER) constitutes an undesirable side reaction, which diminishes chlorine selectivity. The active component in the anode material is RuO2with the (110) facet as most stable surface termination, for which the elementary reaction steps on an atomic scale of the competing CER and OER are already resolved. Here, the selectivity issue and the stability range of a RuO2(110) electrode are explored under CER/OER conditions by combining the kinetic description with surface Pourbaix diagrams and linear scaling relationships. These investigations directly merge into a advanced material screening approach, indicating that the free energy difference between the limiting OOH (OER) and OCl (CER) adsorbate is reconciled as a measure for stability and CER selectivity. This finding supports computational researchers within their search of improved electrode materials based on transition metal oxides for electrocatalytic chlorine formation.

3D multiporous Co,N co-doped MoO2/MoC nanorods hybrids as improved electrode materials for highly sensitive simultaneous determination of acetaminophen and 4-aminophenol

3D multiporous Co, N co-doped MoO2/MoC (3D Co,N-MoO2/MoC) nanorods hybrids were successfully synthesized via carburizing core-shell ZIF-67-cladded MoO3 nanorods precursor at high temperature. As-fabricated Co,N-MoO2/MoC nanorods coated glassy carbon electrodes (GCE) was demonstrated to possess superior electrocatalytic activity for the electro-oxidation of acetaminophen (AC) and 4-aminophenol (4-AP). Such excellent electrochemical performance was largely attributed to the synergistic effect of the unique multiporous structure, the optimal component and abundant active sites of the nanorods. The corresponding electrode reaction mechanisms were studied in detail in this article. Under optimal conditions, the linear detection ranges were 0.05–200.0 μmol/L for AC and 0.05–140.0 μmol/L for 4-AP, respectively, with the low detection limits of 0.013 μmol/L and 0.012 μmol/L. Furthermore, the 3D Co,N-MoO2/MoC/GCE revealed excellent sensitivity, good reproducibility, stability and anti-interference ability. The developed electrode was evaluated towards the detecting AC and 4-AP in biological fluids, environment water and pharmaceutical formulations with satisfactory recovery, which had a broad application prospect.

Comparison of energy consumption in desalination by capacitive deionization and reverse osmosis

Capacitive deionization (CDI), which is based on the electrosorption of ions by porous electrodes, is an emerging technology for brackish water desalination. Understanding the key drivers of energy consumption in CDI and benchmarking CDI with reverse osmosis (RO), the current state-of-the-art for brackish and seawater desalination, is crucial to guide the future development of desalination technologies. In this study, we develop system-scale models to analyze the energy consumption and energy efficiency of CDI and RO over a wide range of material properties and operating conditions. Using our models, we explore how the energetic performance of CDI and RO compare as a function of feed salinity, water recovery, salt rejection, and average water flux, which is normalized by electrode and membrane area in CDI and RO, respectively. Our analysis shows that RO is significantly more energy efficient than CDI, particularly when targeting higher salinity feed streams and higher salt rejection values. For brackish water with a salt concentration of 2000 mg L−1, achieving 50% water recovery and 75% salt rejection, with an average water flux of 10 L m−2 h−1 using CDI requires a specific energy consumption of 0.85 kWh m−3, more than eight times that of RO (0.09 kWh m−3). Importantly, our results also indicate that current efforts to improve electrode materials can only marginally reduce the energy consumption of CDI. We conclude with a discussion highlighting other important factors, such as capital cost, electrode stability, and membrane fouling, which affect the efficacy of CDI and RO for low-salinity desalination.

Controlling Nerve Growth with an Electric Field Induced Indirectly in Transparent Conductive Substrate Materials.

Innovative neurostimulation therapies require improved electrode materials, such as poly(3,4-ethylenedioxythiophene) (PEDOT) polymers or IrOx mixed ionic-electronic conductors and better understanding of how their electrochemistry influences nerve growth. Amphibian neurons growing on transparent films of electronic (metal) conductors and electronic-ionic conductors (polymers and semiconducting oxides) are monitored. Materials are not connected directly to the power supply, but a dipole is created wirelessly within them by electrodes connected to the culture medium in which they are immersed. Without electrical stimulation neurons grow on gold, platinum, PEDOT-polystyrene sulfonate (PEDOT-PSS), IrOx , and mixed oxide (Ir-Ti)Ox , but growth is not related to surface texture or hydrophilicity. Stimulation induces a dipole in all conductive materials, but neurons grow differently on electronic conductors and mixed-valence mixed-ionic conductors. Stimulation slows, but steers neurite extension on gold but not on platinum. The rate and direction of neurite growth on PEDOT-PSS resemble that on glass, but on IrOx and (Ir-Ti)Ox neurites grow faster and in random directions. This suggests electrochemical changes induced in these materials control growth speed and direction selectively. Evidence that the electric dipole induced in conductive material controls nerve growth will impact electrotherapies exploiting wireless stimulation of implanted material arrays, even where transparency is required.

Electrochemical Upgrading of Bio-Oil

Bio-oil produced by fast pyrolysis of biomass is a potential source of low carbon, renewable hydrocarbon fuel. However, the properties such as low heating value, incomplete volatility, acidity, instability, and incompatibility with standard petroleum fuels significantly restrict its use as fuel. The undesirable properties of pyrolysis oil result from its chemical composition that mostly consists of different classes of oxygenated organic compounds. The elimination of oxygen is thus necessary to transform bio-oil into a liquid fuel that would be broadly accepted and economically attractive. Hydrodeoxygenation (HDO) or hydrotreating involves high-temperature, high-pressure processing in the presence of hydrogen and catalyst to remove oxygen. HDO suffers from significant challenges such as coking, deactivation of HDO catalysts by the presence of water in the pyrolysis oil, requirement of significant quantities of hydrogen to remove oxygen, and economic availability of hydrogen at a scale suitable for distributed biomass conversion. An alternative economically feasible, less hydrogen dependent and decentralized process is required to convert bio-oil to refinery ready hydrocarbons. A process of deoxygenation of bio-oil using solid-state, oxygen conductor based electrochemical cell is under investigation. The cell is operated at 500 – 550 °C to match the typical pyrolysis temperature for both physical and process integration of the two operations. The electrolysis process removes oxygen from the oxygenated organic molecule as well from steam to produce hydrogen in-situ. Thus, relatively small quantities of external hydrogen may be needed for deoxygenation, allowing for a distributed, small scale integrated upgrading unit. Mixtures of model compounds were tested using button cells and short stacks. The product from the electrochemical cell contained a suite of compounds with significantly lower oxygen content. Integrated testing of short stacks at the Pacific Northwest National Laboratory using a slip stream from a pyrolyzer shows that the product composition is similar to catalytic pyrolysis process. Additional tests are planned using improved electrode materials. Acknowledgment: This material is based upon work supported by the Department of Energy under Award Number DE-EE0006288.

Applications of Electro-Fenton for Sustainable Water Treatment and Reuse: A Case Study in the Electronics Industry

Electrochemistry has an important role to play in increasing the sustainability and energy efficiency of water treatment and reuse systems. In Singapore for example, the water demand has been projected to more than double by 2060, with non-domestic water demand expected to account for 70% (560 millions of gallons per day). In this context, industrial water reuse is becoming a necessity and the electronics sector has been identified as one of the priority targets due to the extra-pure water requirements. The main issue with industrial water reuse is the removal of “hard-to-treat” contaminants and current interest is focusing on advanced oxidation processes (AOPs), because they produce highly oxidizing species like •OH radicals that can non-selectively mineralize all sorts of organic pollutants. Among them, electro-Fenton has emerged because of its many advantages, including ease of operation and high degradation rates of numerous organic pollutants, thanks to the recent development of improved electrode materials (e.g., carbon nanotubes, graphene, etc.) (1-3). In this work, we showcase the performance at lab-scale and pre-pilot scale of an electro-Fenton prototype to treat a real waste stream from a semi-conductor factory using a novel carbon-fiber brush cathode. First, the brush was fully characterized in terms of its electrical conductivity and surface area. Its interfacial charge-transfer resistance (R ct) – as determined by electrochemical impedance spectroscopy – equaled 1.40 Ω. Cyclic voltammetry was used to determine the electroactive surface area of the electrode, which was found equal to 416 cm2, by using the Randles-Sevcik equation (Eq. 1): Ip = 2.69 × 105 × AD 1/2 n 1/2 γ 1/2 C (Eq. 1) where Ip is the peak current (A), n is the number of electrons participating in the redox reaction (n = 1), A is the area of the electrode (cm2), D is the diffusion coefficient of the molecule in solution (7.60 × 10-6 cm2 s-1), C is the concentration of the probe molecule in the bulk solution (1 × 10-5 mol cm-3), and γ is the scan rate of the potential perturbation (0.01 V s-1). The catalytic activity of the novel electrode was then assessed by its capacity to electrogenerate H2O2. Since H2O2 is an intermediate required to produce •OH in the electro-Fenton reaction (Eq. 2) and is easier to detect, due to its longer half-life, its production arguably constitutes a better indicator of the cathode efficiency than the generation of •OH (4, 5): H2O2 + Fe2+ → Fe3+ + •OH + HO- (Eq. 2) The influence of the current density (normalized to the cathode projected surface area) on H2O2 production through cathodic reduction of O2 was thus evaluated and the best results were obtained at 1.25 mA cm-2, yielding a specific maximum H2O2 concentration of 3.00 ± 0.12 mg-H2O2 L-1 cm-2. Upon addition of Fe2+ to trigger the electro-Fenton reaction following Eq. 2, a mineralization efficiency of 80% was attained within 3 hours using real wastewater from the microelectronics industry in a lab-scale batch setup (Fig. 1) and the energy requirement was as low as 0.14 kWh g-1of total organic carbon (TOC). Following these promising results, a continuous-flow pre-pilot scale prototype was designed and a computational flow simulation allowed optimizing various parameters, from electrode spacing to flowrate and mass transfer rates towards the electrodes (Fig. 2). The performance of this pre-pilot prototype was evaluated in the same conditions as the lab-scale reactor, confirming and even improving the results obtained at lab-scale with over 90% TOC removal reached within 3 hours (Fig. 1). However, the energy consumption increased with the intensity of the treatment from 0.8 KWh g-1 of TOC in the first hour to 1.34 kWh/g-1of TOC, after 3 hours, showing that electro-Fenton would be better used as a pre-treatment technology, over a limited period of time. Overall, these results demonstrate the potential of electro-Fenton as a water treatment and reuse technology and constitute an important step towards full-scale applications. A detailed technical economic assessment of the technology for industrial water reuse will be presented at the conference.

PEM fuel cell model and simulation in Matlab–Simulink based on physical parameters

An advanced PEM fuel cell mathematical model is described and realised in four ancillaries in the Matlab–Simulink environment. Where possible, the model is based on parameters with direct physical meaning, with the aim of going beyond empirically describing the characteristics of the fuel cell. The model can therefore be used to predict enhanced performance owing to, for instance, improved electrode materials, and to relate changes in the measured performance to internal changes affecting influential physical parameters. Some simplifying assumptions make the model fairly light in computational demand and therefore amenable to extension to simulate an entire fuel-cell stack as part of an energy system. Despite these assumptions, the model emulates experimental data well, especially at high current density. The influences of pressure, temperature, humidification and reactant partial pressure on cell performance are explored. The dominating effect of membrane hydration is clearly revealed.

Relationship Between Surface Chemistry, Biofilm Structure and Electron Transfer in Shewanella Anodes

A better understanding of how anode surface properties affect growth, development, and activity of electrogenic biofilms has great potential to improve the performance of bioelectrochemical systems such as microbial fuel cells. Carbon-based materials are widely used for electrode materials and can vary in surface properties such as morphology, chemistry, available surface area and wettability. Attachment surface charge and wettability (hydrophilicity/hydrophobicity) may be particularly important to the growth, development and properties of bacterial biofilm and optimization of bio-electrochemical systems performance. We previously reported the importance of hydrophilic moieties and surface morphology on bacterial attachment, dynamics of biofilm formation, and MFC performance.[1] The influence of different functional groups on biofilm properties, and, therefore, subsequent MFC performance is still not well understood. A combination of spectroscopic, microscopic and electrochemical techniques was used to evaluate how electrode surface chemistry influences morphological, chemical, and functional properties of S. oneidensis MR-1 biofilms, to develop improved electrode materials and structures. Confocal laser scanning microscopy (CLSM) is a powerful method providing morphological parameters of biofilm in three-dimensions, as it allows acquisition of images of fully hydrated biofilms at high spatial resolution in lateral and vertical directions. Imaging processing of CLSM 3D volumes of biofilm provides a set of comprehensive parameters that describe heterogeneous biofilm morphology in three dimensions. In this study, we relate surface chemistry and biofilm areal, volumetric and textural parameters properties to electron transfer rates and efficiency. In the first system, we used self-assembled monolayers (SAMs) as electrodes to systematically evaluate well-defined surface chemistries’ influence on MFC performance. SAM-modified gold electrodes were used to eliminate the morphology effects associated with conventional 3-D structured carbonaceous electrodes. [2] In the second system, we extend this approach for biofilms grown on fibrous 3-D carbonaceous materials under different applied potentials using the same biofilm. Two types of metrics can be extracted from 3D CLSM data sets extracted as demonstrated in Figure 1. From binary volumes, we have calculated biovolume, which is a total number of pixels within the volume having a value of 0 due to present bacteria, and porosity which is the ratio of pixels having a value of 1, i.e. where no bacteria are present, to a total number of pixels. Physical dimensions of biofilm clusters were expressed as the average run length which is the average number of consecutive biomass pixels representing cell cluster in a given direct in the 3d volume. Euler number is an important topological characteristic which is related to connectivity of biofilm formed. The second set of metrics is derived from grayscale intensity is texture parameters. The first parameter is entropy which measures the degree of randomness in the image. The increase in a number of cell clusters due to growth results in more complex textures and more heterogeneous images as shown in the example in Figure 1, which is reflected in higher entropy. Uniformity of the image is related to the orderliness of the structure and is sensitive to change in disorder. Homogeneous images with fewer repeated patterns have higher uniformity while frequent and repeated patterns of pixel clusters as shown in example results in has higher uniformity. For the model SAM-based system, we demonstrate that positively charged, highly functionalized hydrophilic surfaces are optimal for growth of a uniform biofilm with the smallest cluster size and inter-cluster diffusion distance correlating to the most efficient electron transfer. Moreover, we followed the evolution of biofilm morphology during its growth and after electrode polarization for both flat and fibrous systems. We propose metrics describing the loss of biomass, change in inter-cell properties and overall biofilm morphology, based on quantifying biofilm properties from 3D CLSM images directly related to biofilm electron transfer efficiency and stability. 1. Santoro, C., et al., The effects of carbon electrode surface properties on bacteria attachment and start up time of microbial fuel cells. Carbon, 2014. 67(0): p. 128-139. 2. Artyushkova, K., et al., Relationship between surface chemistry, biofilm structure, and electron transfer in Shewanella anodes. Biointerphases, 2015. 10(1). Figure 1

Improved electrode material for deep brain stimulation.

Deep brain stimulation (DBS) devices have been implanted for treatment of basic tremor, Parkinson's disease and dystonia. These devices use electrodes in contact with tissue to deliver electrical pulses to targeted cells, to elicit specific therapeutic responses. In general, the neuromodulation industry has been evolving towards smaller, less invasive electrodes. However, current electrode materials do not support small sizes without severely restricting the stimulus output. Hence, an improved electrode material will benefit present and future DBS systems. In this study, five DBS leads were modified using a cost-effective and materials-efficient process for applying an ultra-low impedance platinum-iridium alloy coating. One DBS lead was used for insertion test and four DBS leads were chronically pulsed for 12 weeks. The platinum-iridium alloy significantly improved the electrical properties of the DBS electrodes and was robust to insertion into brain and to 12 weeks of chronic pulsing.

Development, Manufacturing and Deployment of SOFC-Based Products at SOLIDpower

SOLIDpower provides efficient energy solutions based on its proprietary planar SOFC technology. The first commercial product of the company is the EnGen™-2500. The company deploys the CE certified 2.5 kW combined heat and power generator within the FCH-JU project ene.field and with selected European partners. The EnGen™-2500 uses natural gas for combined heat and power generation (CHP) at high electrical and total efficiencies. The product targets multi-family houses and commercial applications. More than 60 units are to be installed within 2015 and field test results will be presented. SOLIDpower operates a first “to scale” production cell in Northern Italy with a production capacity of 2MW/yr. Based on an ordering volume of 50 MW, the stack and balance of stack components match target market requirements, allowing selling and operating systems at grid parity prices. Besides the micro-CHP generator deployment, SOFCpower also pursues strategic development activities to demonstrate biogas and waste-to-energy (WTE) applications on larger than 2.5 kW scale. SOLIDpower progressed on the technological level for SO Electrolysis. Improved electrode materials and production technology open the door for lifetime for electrolysers stacks beyond 16’000 hrs. SOLIDpower expects that SOFC stack cost reductions stemming from SOFC volume manufacturing can be transferred to a large extend also to SOE stacks. In this field, SOLIDpower intends to work with integration partners on the systems level. The paper provides an update of the stack and system development, including operational results of SOFC-based micro-CHP. SOLIDpower comprises the companies SOLIDpower SpA Italy, SOLIDpower SA Switzerland and SOLIDpower GmbH Germany and unites under its new name the companies formerly known as “SOFCpower SpA” and “HTceramix SA”.

Development, Manufacturing and Deployment of SOFC-Based Products at SOLIDpower

SOLIDpower provides efficient energy solutions based on its proprietary planar SOFC technology. The first commercial product of the company is the EnGen™-2500. The company deploys the CE certified 2.5 kW combined heat and power generator within the FCH-JU project ene.field and with selected European partners. The EnGen™-2500 uses natural gas for combined heat and power generation (CHP) at high electrical and total efficiencies. The product targets multi-family houses and commercial applications. More than 60 units are to be installed within 2015 and field test results will be presented. SOLIDpower operates a first “to scale” production cell in Northern Italy with a production capacity of 2MW/yr. Based on an ordering volume of 50 MW, the stack and balance of stack components match target market requirements, allowing selling and operating systems at grid parity prices. Besides the micro-CHP generator deployment, SOFCpower also pursues strategic development activities to demonstrate biogas and waste-to-energy (WTE) applications on larger than 2.5 kW scale. SOLIDpower progressed on the technological level for SO Electrolysis. Improved electrode materials and production technology open the door for lifetime for electrolysers stacks beyond 16’000 hrs. SOLIDpower expects that SOFC stack cost reductions stemming from SOFC volume manufacturing can be transferred to a large extend also to SOE stacks. In this field, SOLIDpower intends to work with integration partners on the systems level. The paper provides an update of the stack and system development, including operational results of SOFC-based micro-CHP.

Design and Optimization of 3DSi Electrode for Li-Ion Battery Applications

Lithium ion batteries are revolutionized today's information-rich e-society due to their light weight and high energy density. Despite their great success in portable electronic devices at the present time, interest is continued in advancing new and improved electrode materials for lithium ion batteries with higher energy capacity and longer cycle life. Silicon is one of the most promising anode materials for lithium batteries, as it appeals with highest theoretical specific capacity (4200 mAh/g) among known materials, relatively low cost, and environmental benignity. However, silicon anodes suffering from huge volume change associated with the insertion and extraction of lithium during charge-discharge process. Such an unavoidable volume changes result to cracking and pulverization of the anode, which leads to a loss of electrical contact and eventual fading of capacity upon cycling. Herein, we report a porous three-dimensional framework of current collectors to form 3DSi nanostructure to provide continuous electron transport network and accommodate the volume expansion of Si particles. 3D porous Ni current collectors are prepared by galvanostatic electrodeposition with tuning its experimental parameters such as deposition current and pH of bath solution etc. Silicon is deposited conformally by plasma enhanced chemical vapor deposition (PECVD) technique. During PECVD process, parameters such as time, flow rate of the silane gas (SiH4), pressure and power are optimized to ensure uniform conformal coating of Si to form desired three-dimensional silicon structure. X-ray diffraction and Microscopy analysis revealed the formation of 3DNi current collectors by electrodeposition and conformal coating of Si by PECVD. Electrochemical studies such as cyclic voltammetry, electrochemical impedance spectroscopy and charge-discharge studies have been carried out to understand the influence of 3D structure on silicon capacity and cycle life properties. Such a 3D Si electrodes exhibit capacity of 2600 mAh/g with an excellent columbic efficiency at 0.2 C rate for 100 cycles. Further, full cell configuration has been fabricated using LiFePO4/C cathode to demonstrate feasibility of presently designed 3D Si electrode for high capacity Li-ion battery applications. # - Corresponding Author - leela.arava@wayne.edu

Relationship between surface chemistry, biofilm structure, and electron transfer in Shewanella anodes.

A better understanding of how anode surface properties affect growth, development, and activity of electrogenic biofilms has great potential to improve the performance of bioelectrochemical systems such as microbial fuel cells. The aim of this paper was to determine how anodes with specific exposed functional groups (-N(CH3)3 (+), -COOH, -OH, and -CH3), created using ω-substituted alkanethiolates self-assembled monolayers attached to gold, affect the surface properties and functional performance of electrogenic Shewanella oneidensis MR-1 biofilms. A combination of spectroscopic, microscopic, and electrochemical techniques was used to evaluate how electrode surface chemistry influences morphological, chemical, and functional properties of S. oneidensis MR-1 biofilms, in an effort to develop improved electrode materials and structures. Positively charged, highly functionalized, hydrophilic surfaces were beneficial for growth of uniform biofilms with the smallest cluster sizes and intercluster diffusion distances, and yielding the most efficient electron transfer. The authors derived these parameters based on 3D morphological features of biofilms that were directly linked to functional properties of the biofilm during growth and that, during polarization, were directly connected to the efficiency of electron transfer to the anode. Our results indicate that substratum chemistry affects not only primary attachment, but subsequent biofilm development and bacterial physiology.

Influence of bulk fibre properties of PAN-based carbon felts on their performance in vanadium redox flow batteries

Polyacrylonitrile (PAN)-based carbon felts with different fibre properties were studied in terms of their suitability as porous flow-through electrode materials in all vanadium redox flow batteries. The crystallinity and their bulk hetero element content (in particular nitrogen) of the carbon fibres was shown to produce a significant effect on the electrocatalytical properties of the electrodes towards vanadium species. Similar effects were seen on the capacity losses associated with concomitant hydrogen evolution. Adjustments of fibre properties offer the potential of manufacturing improved electrode materials, potentially without additional steps such as surface activation or decoration with catalytically active species.

Local State-of-Charge Inhomogeneities in Charged and Cycled High Capacity Lithium-Manganese-Rich Composite Cathodes

Materials for electrochemical energy storage often exhibit significant chemical and structural inhomogeneity at the particle and even sub-particle level. Understanding how these mesoscale variations in the state of charge and local phase transformations impact electrochemical performance is critical to developing improved electrode materials. Raman microscopy is an excellent technique for studying inhomogeneity and interfacial phenomena in batteries, because it can measure subtle changes in chemical composition and structure at sub-micron resolution. By monitoring changes in the spectroscopic signatures, we can infer information about ion and electron transport across interfaces and through particles. In this study we use ex situ Raman mapping to study layered-layered lithium-rich manganese-rich cathode material Li1.2Mn0.525Ni0.175Co0.1O2 (LMR-NMC) as a function of the average charge. We show that variations in the microstructure and local state of charge occur at the level of individual particles within electrodes prepared from a commercial sample. Micro-Raman mapping provides both high-resolution and large field of view, but the full potential of this technique to analyze complex electrochemical systems is rarely realized, in part due to the challenge of processing the inherently large data sets. Here we take advantage of cluster analysis and other statistical methods to directly visualize interfaces and charge inhomogeneity in cathode particles. Acknowledgment This research at Oak Ridge National Laboratory, managed by UT Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725, is sponsored by the Vehicle Technologies Program for the Office of Energy Efficiency and Renewable Energy.

Electrophoretic Deposition of Multi-walled Carbon Nanotube on a Stainless Steel Electrode for use in Sediment Microbial Fuel Cells

Sediment microbial fuel cells (SMFCs) could be used as power sources and one type of new technology for the removal of organic matters in sediments. In order to improve electrode materials and enhance their effect on the performance, we deposited multi-walled carbon nanotube (MWNT) on stainless steel net (SSN). Electrophoretic deposition technique as a method with low cost, process simplicity, and thickness control was used for this electrode modification and produced this novel SSN-MWNT electrode. The performances of SMFCs with SSN-MWNT as electrode were investigated. The results showed that the maximum power density of SMFC with SSN-MWNT cathode was 31.6 mW m(-2), which was 3.2 times that of SMFC with an uncoated stainless steel cathode. However, no significant increase in the maximum power density of SMFC with SSN-MWNT anode was detected. Further electrochemical analysis showed that when SSN-MWNT was used as the cathode, the cathodic electrochemical activity and oxygen reduction rate were significantly improved. This study demonstrates that the electrophoretic deposition of carbon nanotubes on conductive substrate can be applied for improving the performance of SMFC.

Effect of graphite felt and activated carbon fiber felt on performance of freshwater sediment microbial fuel cell

AbstractBACKGROUND: Sediment microbial fuel cells (SMFCs) could be used as power sources and one type of new technology for the removal of organic matters in sediments. Various types of materials have been used as electrodes. Nevertheless, there is still room to improve electrode materials and enhance their effect on the performance of SMFCs. In this work, performances of SMFCs with activated carbon fiber felt (ACFF) and with nitric acid‐treated ACFF were compared with graphite felt (GF) materials.RESULTS: The maximum power density of the SMFC with ACFF electrode was the highest (33.5 ± 1.5 mW m−2). Nitric acid‐treated GF electrode slightly increased the maximum power density of SMFC, while the nitric acid treated‐ACFF resulted in significant decline in the maximum power density of SMFC. The maximum power density further increased to 74.5 ± 7.5 mW m−2 in SMFC using GF cathode and ACFF anode.CONCLUSIONS: ACFF as anode can enhance the transport of electrons from the oxidation of organic matter in the sediment, while the output power was found to reduce in SMFC with ACFF cathode. Further efforts are needed to study the formation conditions of the biocathode and new electrode modification technology. Copyright © 2012 Society of Chemical Industry

High specific capacity and excellent stability of interface-controlled MWCNT based anodes in lithium ion battery

ABSTRACTRechargeable batteries are in high demand for future hybrid vehicles and electronic devices markets. Among various kinds of rechargeable batteries, Li-ion batteries are most popular for their obvious advantages of high energy and power density, ability to offer higher operating voltage, absence of memory effect, operation over a wider temperature range and showing a low self-discharge rate. Researchers have shown great deal of interest in developing new, improved electrode materials for Li-ion batteries leading to higher specific capacity, longer cycle life and extra safety. In the present study, we have shown that an anode prepared from interface-controlled multiwall carbon nanotubes (MWCNT), directly grown on copper current collectors, may be the best suitable anode for a Li-ion battery. The newly developed anode structure has shown very high specific capacity (almost 2.5 times as that of graphite), excellent rate capability, nil capacity degradation in long-cycle operation and introduced a higher level of safety by avoiding organic binders. Enhanced properties of the anode were well supported by the structural characterization and can be related to very high Li-ion intercalation on the walls of CNTs, as observed in HRTEM. This newly developed CNT-based anode structure is expected to offer appreciable advancement in performance of future Li-ion batteries.

TiN Coated ZnO Powder as Improved Electrode Material for Secondary Ni-Zn Batteries

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