Anode Electrode Surface Research Articles

Evaluation of Solar Conversion Efficiency in Dye-sensitized Solar Cells Using Natural Dyes Extracted from Alpinia purpurata and Alstroemeria Flower Petals as Novel Photosensitizers

Herein, we evaluate the conversion efficiency of dye-sensitized solar cells (DSSCs) photosensitized using two different natural dyes extracted from Alpinia purpurata and Alstroemeria flower petals. The appreciable absorption capacity of the extracts in the visible light region was examined through absorption spectroscopy. The functional groups of the corresponding pigments were identified through Fourier transform spectroscopy (FTIR) technique thus indicating the presence of cyanidin 3-glycosides and piperine in the flowers of Alstroemeria and Alpinia purpurata. The extracted dyes were immobilized on TiO2 on transparent conducting FTO glass, which were used as photoanode. The dye-coated TiO2 photoanode, pt photocathode and iodide/triiodide redox electrolyte assembled into a cell module was illuminated by a light source intensity 100 mW/cm2 to measure the photovoltaic conversion efficiency of DSSCs. The TiO2 anode and Pt counter electrode surface roughness and morphological studies were evaluated using atomic force microscope (AFM) and field emission scanning electron microscopy (FESEM), respectively. Through the photoelectric characterizations, it was promising to verify that the solar conversion efficiency was calculated with the photovoltaic cell sensitized by Alstroemeria and Alpinia purpurata. This was achieved with a yield (η) of 1.74% and 0.65%, with an open-circuit voltage (Voc) of 0.39 and 0.53 V, short-circuit current density (Jsc) of 2.04 and 0.49 mA/cm2, fill factor (FF) of 0.35 and 0.40, and Pmax of 0.280 and 0.100 mW/cm2, respectively. The results are promising and demonstrate the importance of the search for new natural dyes to be used in organic solar cells for the development of devices that generate electricity in a sustainable way.

Enhanced hydrogen production coupled with ethanol electrocatalytic oxidation by flow-through self-supporting electrode

Electrocatalytic oxidation of ethanol to value-added production is an ideal replacement of the conventional anodic oxygen evolution reaction (OER) for efficient hydrogen (H2) production due to the lower electric potential energy and higher safety. However, the sluggish mass transfer rate of reactants commonly is the crucial limitation of electrocatalytic oxidation efficiency. Here, Ni(OH)2 nanosheet is immobilized on nickel foam (NF) to fabricate a flow-through self-supporting electrode (Ni(OH)2/NF) served as anode for ethanol electrocatalytic oxidation, in coupling with high-purity H2 production at the cathode. The potential for electrocatalytic oxidation of ethanol and H2 evolution was significantly reduced by 200 mV compared to pure water splitting at 25 mA cm−2. The boundary layer thickness on the anodic electrode surface could be decreased from 86.66 μm to 66.21 μm with the flow rate increased from 0 to 0.82 cm min−1. Compared to the batch mode, The conversion rate of ethanol can be increased from 59 % to 100 % and the selectivity of acetic acid can be increased from 88 % to 100 % under the flow-through mode. The Faraday efficiency of the anode achieved an increase from 76 % to over 99 % and the H2 production of the cathode increased by 31 % under the flow-through mode.

Removal of Diclofenac Sodium from Wastewater in Microbial Fuel Cell by Anode Modified with MnCo2O4

Microbial fuel cell (MFC) with a modified anode is one of the new methods to increase MFC efficiency. This study synthesized an anode modified with cobalt manganese oxide (MnCo2O4@CF) on carbon felt (CF) by easy hydrothermal method and binder-free. Chemical oxygen demand (COD) was measured with and without diclofenac (DCF). According to SEM results, MnCo2O4 was uniformly dispersed on the anode electrode surface. Moreover, the maximum power density in COD (1000 mg/L), 48 h. condition without DCF (726 mA/m2) was 165 ± 0.012 mW/m2 and with DCF concentration of 20 mg/L, it was 308 ± 0.013 mW/m2 (992 mA/m2). In addition, in the presence of 10 mg/L DCF concentration, the maximum COD removal efficiency was 82% ± 1.93 at 48 h. COD removal efficiency without DCF was 94.67% ± 0.02 at 72 h. After 72 h, the maximum removal efficiency of COD and DCF in the carbon anode was 41% ± 1.15 and 9.5% ± 0.23, respectively. Moreover, the maximum DCF removal efficiency using a MnCo2O4 anode was 56% ± 0.55, at 48 h; the initial COD concentration was 500 mg/L, and the DCF concentration was 20 mg/L. This research showed that coating the anode with MnCo2O4 could lead to the increased growth of microorganisms on the surface of the anode, decreased load transfer resistance, increased power density, and more removal of COD and DCF. As a result, the performance of fuel cells with modified anode and removal of DCF increased compared to anode with CF-MFC. Thus, the performance of fuel cells with modified anode and removal of DCF increased compared to anode with CF-MFC.

Bio-Electrochemical Performance of a Ceramic Microbial Fuel Cell Treating Kitchen Waste Leachate: Effect of Organic Loading Rate and Anode Electrode Surface Area

Performance evaluation of a ceramic microbial fuel cell (CMFC) by varying organic strength, hydraulic retention time (HRT) and anode electrode surface area (AESA) to treat leachate generated from acidogenesis of kitchen waste (KW) was studied by the central composite design of experiment. The increase in organic loading rate (OLR) positively affected power density (PD) while negatively influencing organic removal and coulombic efficiency (CE). This behavior is possible due to substrate inhibition and the coercive effect of low HRT, i.e., substrate washout, biofilm abrasion, and reduced contact period, while at high HRT, the volatile fatty acid (VFA) degradation improved. Since acetic acid is the final product of long-chain VFAs degradation, a pseudo consumption order for VFAs was obtained: butyric > propionic > acetic. The AESA aided organics removal and PD but had a negligible effect on CE. According to ANOVA, the COD removal was linearly modeled, while PD and CE were quadratic. The validation runs (VR) proved efficient as the highest COD removal was for VR2 (83.7 ± 3.6%), while maximum PD and CE values obtained were 0.224 ± 0.02 W/m3 and 2.62 ± 0.33%, respectively, for VR3, supported by the lower anode potential.

Oxidation and oriented attachment growth of colloidal nanoparticles during electrophoretic deposition

• The electrophoretic deposition can be a chemical oxidization and oriented attachment process. • The charge type of the Ag nanoparticles changes during electrophoretic deposition. • Ag 2 O 2 nanocubes are assembled from Ag 2 O 2 nanoparticles oxidized from Ag nanoparticles. Electrophoretic deposition (EPD) has been widely used to assemble nanoparticles into dense nanoparticle films. Here, we discovered that the EPD might be not necessarily the widely accepted physical pile-up process, but a chemical oxidization and oriented attachment growth process. During EPD of silver colloids prepared by laser ablation of a piece of silver plate in pure water without any chemicals introduced, we observed formation of sub-microscale well-defined silver peroxide (Ag 2 O 2 ) cuboids on the anode electrode surface. The Ag 2 O 2 nanoparticles were oxidized from the Ag nanoparticles during EPD. Fusion between neighbouring Ag 2 O 2 nanoparticles through oriented attachment and Ostwald ripening process rendered the formation of the Ag 2 O 2 cuboids. This study revealed a new growth mechanism during EPD, strengthening the capability of EPD during designing micro/nanostructures.

Integrating operating conditions to develop a neural network for predicting organics removal and power density in an earthen microbial fuel cell treating leachate

Nowadays, the acceptability of artificial neural networks (ANNs) to develop models for biological treatment systems has been broadened instead of the complex mechanistic mathematical model. The present study attempts to train neural networks to predict organics removal and power output from an earthen microbial fuel cell treating acidogenic leachate obtained from kitchen waste. To model the effluent chemical oxygen demand (COD) and volatile fatty acid (VFA) values and power density, the study used four input parameters: influent COD, and VFA, hydraulic retention time, and anode electrode surface area. Among the multiple algorithms employed, the Bayesian inference proved to deliver a winning model to forecast the response variable with an overall high coefficient of determination of 0.9890. This high correlation for a biological system employing a real substrate, i.e. leachate, ensures the model’s reproducibility and adequacy. Additionally, the statistical error criteria for model efficacy showed acceptable values. Besides, the study performs validation runs with an error of approx. 11% with conservative predictions. Ultimately, the ANN model fared well in predicting the response for effluent COD and power output when compared with kinetic study (Han-Levenspiel) and statistical equation (from ANOVA) to the experimental values.

Insights on the electrochemical performance of a molten proton conductor fuel cell with internal methanol reformer

A fuel cell based on a molten proton conductor electrolyte membrane, in which polybenzimidazole (PBI) membrane is doped with molten CsH5(PO4)2, has been integrated in a single cell arrangement with a CuZn-based methanol reformer. It is demonstrated that the fuel cell with the internal reformer can efficiently operate at 220 °C, which is higher temperature than the upper limit of previously reported high-temperature proton exchange membrane fuel cell with an H3PO4-doped PBI membrane. Furthermore, the fuel cell with the internal reformer is able to provide 0.7 V at 200 mA cm−2 at 220 °C, keeping an open circuit voltage above 1 V, similarly with that under hydrogen feed at the same temperature. Electrochemical characterization of anode electrode surface area, also employing cyclic voltametry and impedance spectroscopy suggests that a performance decay after a transient operation with several on-off cycles, is due to proton conductor loss in the electrode's catalyst layer of the single cell.

An all-in-one approach for self-powered sensing: A methanol fuel cell modified with a molecularly imprinted polymer for cancer biomarker detection

• A hybrid methanol fuel cell operating with a biosensor. • One electrode of the fuel cell is the biosensing element. • A molecularly-imprinted polymer tailored in situ for carcinoembryonic antigen. • The overall power of the hybrid cell is carcinoembryonic antigen concentration dependent. • This hybrid fuel cell pursues an application in point-of-care. This work describes the development of an innovative electrochemical biosensor comprehending a passive direct methanol fuel cell (DMFC) assembly, modified by a layer of a molecularly imprinted polymer (MIP) on a carbon fabric anode electrode containing Pt/Ru nanoparticles. This MIP film was prepared from poly(3,4-ethylenedioxythiophene) (PEDOT) and polypyrrole (PPy) obtained by in situ electropolymerization of the corresponding monomers on the anode electrode surface. This MIP film is designed to detect an important cancer biomarker- carcinoembryonic antigen (CEA). This innovative, all-in-one device works in a simple way. First, CEA is incubated on the anode container of the fuel cell, then methanol is added, followed by the response evaluation (polarization curves determination). As CEA selectively interacts with the MIP film, it blocks the methanol's access to the Pt catalyst, remains specific bonded, and interferes with the subsequent polarization curves of the DMFC. Polarization curves obtained in the presence of standard solutions prepared in buffer and human serum confirmed linear responses of log CEA concentration ranging from 30 to 30 000 ng/mL in both media. The biosensor DMFC showed a sensitive response with a detection limit of 4.41 ng/mL when an aqueous 0.05 M methanol solution was used as fuel. When methanol was replaced by an ethanol solution of the same concentration (using the same setup developed for the DMFC), the lower detection limit of 3.52 ng/mL was obtained. Overall, the obtained results show that methanol/ethanol fuel cells operating without flow-through can be successfully used for the fabrication of self-powered biosensors. The novel biosensor concept presented here is simple, inexpensive, and effective, and can be further developed to meet point-of-care requirements.

Analysis and modeling of high-performance polymer electrolyte membrane electrolyzers by machine learning

In this study, box and whisker and principal component analysis, as well as classification and regression tree modeling as a part of machine learning were performed on a database constructed on PEM (polymer electrolyte membrane) electrolysis with 789 data points from 30 recent publications. Box whisker plots discovered that pure Pt at the cathode surface, Ti at the anode support, the existence of Pt, Ir, Co, Ru at the anode surface, Ti porous structures at the electrodes, pure water-electrolyte and Nafion and Aquivion type membranes in proton exchange electrolyzer provide the highest performances. Principal component analysis indicated that when cathode surface consists of mostly pure Ni, when anode electrode has no support or vanadium (10–20%) doped TiO2 support and when anode electrode surface consists of cobalt-iron alloys (0.5:0.5 and 0.333:0.666 mol ratio) or RuO2, there is a risk for low-performance. Classification trees revealed that other than current density and potential, cathode surface Ni mole fraction, anode surface Co mole fraction are the most important variables for the performance of an electrolyzer. Finally, the regression tree technique successfully modeled the polarization behavior with a RMSE (root mean square error) value of 0.18.

Fouling and corrosion of electrode plates in nickel cadmium batteries

The aim of this study is investigation of fouling propensity in nickel cadmium electrodes after degradation of alkaline-electrolyte from rich-hydroxide to rich-carbonate along with time. Gradually, CO2 absorption from the air into the alkaline electrolyte leads to the destruction of electrodes and the formation of precipitated layers resulting in reduction of electrical capacity and life time of batteries. Based on the microscopic observations (SEM), spectroscopic evidences (FTIR and XRD) and thermal experiments (TG-DTA) significant damages and fouling phenomena were categorized as: salt islands, graphite films, etched graphite, cadmium dendrites, cadmium oxide/sulfide and cathodic corrosion. The experimental results revealed that nickel cathodes have experienced more surface damages with respect to cadmium anodes. Although the anode is the source of cadmium species, however the fouling layers of cadmium oxide and cadmium sulfide were assigned to be the main causes of cathode damage, leading to the decreasing of electrode current and the increasing of internal resistance of the cells. On the other hand, the main damage on the surface of anode electrode was attributed to graphite coatings and cadmium hydroxide stripped from the cathode. The microscopic observations showed that almost 2% of cathode surface was corroded, while the anode surface had experienced no corrosion.

Investigation of Polymer Biofilm Formation on Titanium-Based Anode Surface in Microbial Fuel Cells with Poplar Substrate

Microbial fuel cells (MFCs) have attracted attention by directly converting the bioelectrochemical energy possessed by the organic materials that make up the biomass into electrical energy. In this study, the relationship between the biofilm formed on the titanium-based anode electrode surface, and the chemical composition of the substrate, the energy source of MFC, was investigated. For this, MFCs were made by using poplar wood shavings rich in organic material as the substrate, titanium-based material as the anode electrode, and natural soil as bacterial habitat. Three types of MFCs containing 1%, 10%, and 20% poplar wood shavings by weight were made and named P1-MFC, P2-MFC, and P3-MFC, respectively. According to electrochemical analysis, P3-MFC provided the highest open circuit voltage with 490 mV value, and the highest power density with 5.11 mW/m2 value compared to other MFCs. According to optical microscopy examinations, there were Bacillus and Coccus species of bacteria in the soil structure, and these bacteria also existed around the fiber of poplar wood shavings in MFCs. Scanning electron microscopy (SEM), energy-dispersive spectrum (EDS), and Fourier transform infrared spectroscopy (FTIR) analysis showed that MFCs formed biofilm in the titanium-based anode, and the chemical composition of this biofilm with poplar tree was similar. As a result, due to the catalysis reactions of bacteria, the titanium-based anode electrode surface was coated with polymer biofilm released from poplar wood shavings.

Investigation of electricity generation performance of grape marc in membrane-less microbial fuel cell

Grapes are among the most widely grown fruits globally, with a third of the overall production used in winemaking. Both red and white winemaking processes generate significant amounts of solid organic waste such as grape marc that requires proper disposal. Grape marc, a natural plant product containing abundantly lignocellulosic compounds, is a promising raw material for production of renewable energy. In this study, the grape marc was used as an anode nutrient in the membrane-less microbial fuel cell (ML-MFC) system, and the electricity generation capacity of the grape marc as an environmentally friendly energy source was investigated in detail. The maximum power density produced in the ML-MFC reactor was determined as 274.9 mW m-2, and the total internal resistance was 309.5 Ω. Cyclic voltammetry results showed the presence of electroactive microorganisms on the surface of the anode electrode provided a high biological activity. The presence of elliptical and round-shaped microorganisms on the anode electrode surface was observed. Quantitative polymerase chain reaction (qPCR) analyzes have shown that grape marc supports bacterial growth on the electrode surface.

Eco-friendly NaCl-based electrolyte for electropolishing 316L stainless steel

Abstract Since the environmental and safety issues closely related to the widely used mixture electrolytes of H2SO4 and H3PO4 in electropolishing 316 L stainless steel, the development of new electrolytes, which do not contain any acid is of a great demand. This study is to electropolish 316 L stainless steel in a NaCl-based electrolyte, not containing any acid as the conventionally used electrolytes. The electropolishing effect with the NaCl-based electrolyte is compared with the conventional H2SO4-based electrolyte. The experimental results show that the proposed electrolyte can be used for the electropolishing of 316 L stainless steel to obtain a comparable electropolishing effect with the conventional H2SO4-based electrolyte. Moreover, the NaCl-based electrolyte shows a higher material removal rate than the H2SO4-based electrolyte. It is also found that a brown product generated and covered on the anode electrode surface during the electropolishing with the NaCl-based electrolyte. According to the EDS analysis, it mainly contains dissolved metal elements, Cl and Na element from the used electrolyte. Furthermore, the electropolishing effect can be improved by the ethanol addition in the NaCl-based electrolyte due to the reduced influence of the brown product.

Modeling the influence of substrate concentration, anode electrode surface area and external resistance in a start-up on the performance of microbial fuel cell

In the present research, the conduction-based model was used for investigating influence of anode surface area, substrate concentration and start-up method on the performance of microbial fuel cells (MFC), utilized in wastewater treatment systems. Maximum produced power increased by about 9% when external resistance enhanced from 100 to 1000 Ω in the start-up. The results show that power increased rapidly (from 0.024 to 3.66 mW) with increasing the initial chemical oxygen demand (COD) of substrate from 0.01–2 g/L. However, when COD was increased from 2 to14 g/L, produced power remained almost constant (3.66–3.81 mW). The surface area of the anode had a different effect on power and power density. Produced power enhanced by increasing surface area of the anode. However, the effect of surface area of anode on power density was different and had an optimum value, which increased in higher COD concentrations.

SURFACE MODIFIED AND BISMUTH LOADED GRAPHITE FELTS FOR IMPROVEMENT OF ANODE ELECTRODE KINETICS IN IRON CHROMIUM REDOX FLOW BATTERY

In this study, anode electrodes were modified and bismuth loaded to enhance chromium redox reaction for iron chromium redox flow batteries. Graphite felt anode electrode surface was modified by two step chemical treatment. Corrosive HF was used as an etchant to increase porosity at the first step and oxidizing H2O2 was used to increase wettability of electrode at the second step. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analyses were used for the physical and chemical characterization of electrode materials. Cyclic voltammetry (CV) and linear sweeping voltammetry (LSV) techniques were conducted to investigate Cr2+/Cr3+ redox reaction kinetics for the modified electrodes with or without bismuth loading. Carbon nanoparticles formed on the surface and oxygen content increased. Contact angle for pristine graphite felt decreased from 132.6° to 128.5°, electrode wettability increased after treatment with HF and H2O2. Dispersion of bismuth particles became more uniform on modified electrode. Compared to untreated felt, the diffusion coefficient for Cr2+ has been almost doubled on modified graphite felt and Cr2+ concentration on the surface increased. When bismuth was in solution, reaction was controlled by charge transfer for modified electrode. In contrast, when bismuth was loaded onto the felt electrodes, reaction became diffusion controlled.

MEMS-Based Microfluidic Fuel Cell for In Situ Analysis of the Cell Performance on The Electrode Surface

The present study investigates various effects of MEMS-based microfluidic fuel cell on the performance of direct formic acid microfluidic fuel cells that breathe air as an oxidant. A miniaturized fuel cell of the structure and design of a typical T-shaped air- breathing Direct Formic Acid Fuel Cell with micro channel is 1.5 mm x 25 mm in width multiply length. Both anode and cathode electrode having a width and length of 0.6 mm and 20 mm, respectively, with an electrode spacing of 0.3 mm. An air-breathing microfluidic fuel cell having a 0.6 mm in width and 20 mm in length that is placed on cathode GDE down-side. In such systems for the fluid delivery, both formic acid (0.5 M) as a fuel solution mixing sulfuric acid (0.5 M) at a node channel side and as an electrolyte used sulfuric acid (0.5 M) place take on the cathode channel side are injected together into the end of the channel outlet by two syringe pumps. Firstly, a three-dimensional microfluidic fuel cell model was established using Computational Fluids Dynamics to simulate the fuel cell performance. Further, both V-I curves obtained from simulation and published experimental data under similar operating condition were compared to assure the validity of the simulation. Modelling the transport and electrochemical phenomena were described with hydrodynamic equations, the porous media flow, mass transport, electrochemical reaction and charge equation. The porous media flow in the gas diffusion layer was described by Brinkman equation. The Butler-Volmer equations were applied to get the V-I-P curves. An anode electrode surface performance, respectively, is presented.

Agri‐food waste valorisation

Agri‐food waste valorisation

Prototype Aqueous Lithium-Ion Battery with a Lithium-Ion Conductive Solid Electrolyte Separator

Lithium-ion batteries (LIBs) with a non-aqueous electrolyte are capable of high energy density, high power output, and long cycle performance. These batteries are regarded as the most promising sources of power for electric vehicles (EVs), hybrid electric vehicles (HEVs), and grid storage. However, current LIBs pose a safety risk due to their flammable organic electrolytes. In contrast, lithium-ion batteries with aqueous electrolytes are safer and cost less than current LIBs, but the electrochemical stability window of aqueous electrolytes is narrower than that of the organic electrolytes used in LIBs. The stable operating voltage window of an aqueous electrolyte is approximately 1.23 V thermodynamically, beyond which the electrolysis of H2O occurs along with the evolution of H2 or O2 gas. As illustrated by a Pourbaix diagram, the overall electrochemical stability window of aqueous electrolytes is constant and independent of the pH of the electrolytes. In this study, we report the widening of the overall electrochemical stability window with two electrolytes having different pH values. We utilized a lithium-ion conductive solid electrolyte to separate the electrolytes into the cathode and anode sides of an aqueous lithium-ion battery in order to suppress the evolution of oxygen and hydrogen. In particular, we fabricated an aqueous lithium-ion cell with a lithium-ion conductive solid electrolyte as the separator between two inorganic lithium salt layers. A spinel lithium manganese oxide (LMO) was used as the cathode active material while a spinel lithium titanate oxide (LTO) with a Li+ insertion potential of 1.55 V vs. Li was used as the anode active material, leading to less hydrogen evolution compared with the graphite anodes used in current LIBs. A lithium-ion ceramic plate (LICGC™, Ohara Inc.) with a thickness 150 µm and conductivity 10-4 S/cm at 25°C was used as the separator. The plate was able to separate the different electrolytes into the cathode and anode sides. Then, 2 mol/L Li2SO4 and 12 mol/L LiCl, both of which have higher conductivity than the organic electrolytes of current LIBs, were used as the cathode and anode electrolytes, respectively. The cell was constructed with an LMO cathode electrode (10 mm in diameter, 0.1 mm thick), an LTO anode electrode (approximately the same dimensions as the cathode), the solid electrolyte separator (2.5 ´ 2.5 cm, 150 µm thick), and an aqueous solution with 2 mol/L Li2SO4 and 12 mol/L LiCl as the cathode and anode electrolyte, respectively. The charge/discharge current density was 0.282 mA/cm2 at the 1C rate. Figure 1 shows the charge and discharge curves of the LMO/LTO cell at the 20th cycle (25°C). The aqueous test cell exhibited an average discharge voltage of over 2.4 V and a coulombic efficiency of over 94%. Figure 2 shows the cycling stability and coulombic efficiencies of aqueous LMO/LTO cells at the 1C rate. To prevent drying of the electrolyte in a long-term experiment, 12 mol/L LiCl was used as electrolytes for both the cathode and anode. The retention of discharge capacity and coulombic efficiency was approximately 100% after 1000 cycles. The coulombic efficiency of the initial cycle, in which the pH of the 12 mol/L LiCl electrolyte was neutral (measured with pH test paper), was relatively low. During the 20th cycle, which had relatively low coulombic efficiency, the anode electrolyte changed from acidic to basic and hydrogen evolution with electrolysis of water was suppressed. After the 20th cycle, the electrolyte pH at the anode electrode surface was close to 14, whereas the entire electrolyte pH was close to neutral. The pH of the local electrolyte, situated between the anode electrode surface and the solid electrolyte separator, changed from acidic to basic, resulting in the suppression of oxygen and hydrogen gas generation without changing the pH of the cathode electrolyte. The initial coulombic efficiency was dependent on the anode electrolyte pH due to the lower coulombic efficiency of the anode compared with the cathode. Additional electrochemical tests will be reported in the future. Figure 1

Nonlinear Aging Characteristics of Lithium-Ion Batteries

As the lithium-ion batteries become increasing prevalent in daily-life and industry, such as electric cars, aircrafts and portable devices, monitoring and predicting battery aging becomes critical. Typically, aging occurs due to multiple complex phenomena and reactions that are occurring simultaneously at different places in battery, and the degradation rate varies between different certain stages during a load cycle, depending on electric potential, local concentration, temperature, and also the direction of current. Battery aging is found to be linear in the early stage of cycling, however, highly non-linear at the end with rapid capacity drop. This nonlinear capacity drop phenomenon is called as “knee-point effect” and the cause leading to this is unexplored. In this work, we investigate this effect, by systematically account the mass and charge transport with interfacial reactions and parasitic solid-electrolyte-interface (SEI) and lithium plating forming reactions at the anode electrode surface as a function of porosity, C-rate and depth-of-discharge. Our findings are expected to improve the understanding of battery aging and we expect this fundamental model formulation to be promising for future predictive battery studies and design optimization.

Novel Analytical Microbial Fuel Cell Design for Rapid in Situ Optimisation of Dilution Rate and Substrate Supply Rate, by Flow, Volume Control and Anode Placement

A new analytical design of continuously-fed microbial fuel cell was built in triplicate in order to investigate relations and effects of various operating parameters such as flow rate and substrate supply rate, in terms of power output and chemical oxygen demand (COD) removal efficiency. This novel design enables the microbial fuel cell (MFC) systems to be easily adjusted in situ by changing anode distance to the membrane or anodic volume without the necessity of building many trial-and-error prototypes for each condition. A maximum power output of 20.7 ± 1.9 µW was obtained with an optimal reactor configuration; 2 mM acetate concentration in the feedstock coupled with a flow rate of 77 mL h−1, an anodic volume of 10 mL and an anode electrode surface area of 70 cm2 (2.9 cm2 projected area), using a 1 cm anode distance from the membrane. COD removal almost showed the reverse pattern with power generation, which suggests trade-off correlation between these two parameters, in this particular example. This novel design may be most conveniently employed for generating empirical data for testing and creating new MFC designs with appropriate practical and theoretical modelling.