Anode Size Research Articles

Facile synthesis of Cu2O nano-microspheres anode for lithium-ion batteries

Transition metal oxide anode materials exhibit high theoretical specific capacities and can meet the energy density requirements through reasonable design. In this work, a facile wet-chemical method to fabricate Cu2O nano-microspheres anode for lithium-ion batteries with controllable size varied from 0.4 ∼ 1.2 μm is introduced, which basically using copper acetate as copper precursor and ascorbic acid as reducing agent. The solvent composition (DI water only or DI water:Ethanol = 1:1), solution alkalinity (amount of NaOH input), and synthesis temperature are investigated as factors affecting the size and morphology of Cu2O nano-microspheres. The samples are characterized by X-ray diffraction, transmission electron microscope and scanning electron microscope. Nanoparticle cluster structure is observed in the reaction product with the bi-solvent system. With the optimized synthesis condition, the prepared Cu2O anode (size of ∼ 455 ± 41 nm) delivers an initial discharge capacity of 539 mAh/g at a current density of 0.5C, 100 cycles of cyclic discharge at 0.5C with a capacity retention rate of 84.73 %. At the current density of 2C, the specific capacity is 347 mAh/g. Even at a large current density of 5C, the specific capacity is still as high as 219 mAh/g, indicating good rate capability.

An Aluminum Anode with Superior Discharge Characteristics Prepared via Grain Refinement

AbstractAs Electric Vehicles became more important in the field of energy, the disadvantages of lithium‐ion batteries became apparent. This led to an increased interest in metal‐air batteries, particularly aluminum‐air batteries, as alternatives to lithium‐ion batteries. However, aluminum‐air batteries also have their own deficiencies, with one of the main areas of research being the improvement of anode characteristics. Improving anode characteristics is a crucial area of research in this field. Aluminum alloys have traditionally been used to overcome obstacles in creating batteries with favorable electrochemical properties. However, recent studies suggest that reducing the grain size of aluminum anodes can have positive effects. In this study, we investigated the electrochemical behavior of three aluminum alloys that were grain‐refined by Al‐5Ti‐1B and compared the results to a commonly used aluminum alloy as an anode in aluminum‐air batteries. We chose Al−Ti alloys with variable amounts of titanium (0.01, 0.05, and 0.1 wt.%) for evaluation. We selected a 4 molar potassium hydroxide solution as the test electrolyte due to the merits of alkaline electrolytes. Our study found that the alloy with 0.05 wt.% of titanium is the best anode choice. This anode has promising discharge characteristics at high current density (50 mA/cm2) and is an appropriate choice for electric vehicles.

Simulation of Hybrid Microbial Fuel Cell-Adsorption System Performance: Effect of Anode Size on Bio-Energy Generation and COD Consumption Rate

Simulation of Hybrid Microbial Fuel Cell-Adsorption System Performance: Effect of Anode Size on Bio-Energy Generation and COD Consumption Rate

The influence of rare earth elements (Ce, La, Y, Nd, Gd) on the microstructure, electrochemical and antibacterial properties of Al-Zn-In-Mg-Ti sacrificial anodes

The influence of incorporating rare earth elements (Ce, La, Y, Nd, Gd) on the performance of Al-Zn-In-Mg-Ti sacrificial anode was investigated. The results demonstrated that the addition of RE has lowered the open circuit potential of Al-Zn-In-Mg-Ti anode, and enhanced its self-corrosion resistance and activation properties. With 2 wt% RE content, the average grain sizes of the sacrificial anodes were reduced to below 100μm, exhibiting conspicuous grain refinement, which fostered an increase in the current efficiency. The current efficiencies of the anodes containing Ce, La, Y, and Nd respectively surpassed 90 %. Furthermore, the anodes with RE showed remarkable antibacterial property.

8.7 A/700 V β-Ga2O3 Schottky barrier diode demonstrated by oxygen annealing combined with self-aligned mesa termination

β-Ga2O3 Schottky barrier diodes (SBDs) with low-defect epitaxial surface and effective termination are essential for realizing excellent blocking characteristics. This work systematically studied oxygen annealing at various temperatures, optimizing the epitaxial surface by reducing the surface roughness and dislocation density. Combined with mesa termination, the results showed that the breakdown voltage (V br) significantly increased from 845 V to 1532 V. The device with a 3 × 3 mm2 anode size was fabricated simultaneously, and the high forward currents of 8.7 A@2 V and V br > 700 V were achieved. This work shows a possible solution for the commercialization of β-Ga2O3 SBDs.

Thomson scattering measurements in the krypton plume of a lanthanum hexaboride hollow cathode in a large vacuum test facility

Laser Thomson scattering is a minimally intrusive diagnostic technique for determining electron temperature, density, and bulk velocity in plasma systems. Advances in technology have made possible the application of Thomson scattering to electric propulsion-relevant plasma systems, with reported electron number-density detection limits as low as 1×1016 m−3, and electron temperatures from one-to-tens eV. However, the implementation of laser Thomson scattering in large vacuum testing facilities, wherein electric propulsion devices are tested, remains a challenge. This work presents the implementation of a laser Thomson scattering system in a large vacuum test facility at the Georgia Tech High Power Electric Propulsion Laboratory. The diagnostic was optimized for maximum light-collection efficiency and ease of re-alignment while the facility is at vacuum. The high light-collection efficiency allowed reduced accumulation times to achieve the target detection limit of 1×1017 m−3. The diagnostic is used to measure axial electron property profiles in the near-field plume of a lanthanum hexaboride hollow cathode operating at 25 A on krypton at a background pressure of 1.3×10−6 Torr—Kr. The diagnostic is quantitatively compared to similar systems in the literature. The resulting axial points, collected from 2 to 8 mm downstream of the cathode keeper orifice, are qualitatively and quantitatively compared with simulations and experimental measurements made with electrostatic probes and laser-induced fluorescence. The main quantitative difference between measured values and results is the one to two order of magnitude difference in the peak electron density, being attributed to the relative size and location of the external anode with respect to the cathode keeper.

Shivalik Plasma Device-I, a glow discharge device to study the collective dynamics of dusty plasma

Using a uniquely configured glow discharge-based Shivalik Plasma Device-I, we demonstrate a variety of collective phenomena in dusty plasma away from the glow discharge region. The cylindrical glass device produces plasma using parallel disc-shaped electrodes with a smaller anode size than the cathode. The dust microparticles are initially sprinkled over the grounded cathode. These particles acquire a significant negative charge upon plasma formation, resulting in their levitation due to the balance between the Coulomb force and gravity. The new device supports the levitation of a big-sized (10 × 8 × 5 cm3) three-dimensional dust cloud over the glass surface. It contrasts the dusty plasma formations in-between electrodes reported earlier. As the discharge voltage varies from high to low, the dust cloud travels from over the glass surface to between the electrodes. A complex interplay of dust void over the cathode, a sharp density gradient, and gravity lead to self-excitation of collective dust phenomena. It includes dust density waves (phase velocity, vph ∼ 4 cm/s), dust cloud oscillation (frequency, f = 5 Hz), sheared flow (flow velocity, vf ∼ 1 cm/s), and multiple-sized dust vortices. These dust vortices provided an excellent platform for studying turbulent mixing phenomena. The power spectrum analysis agreed with two-dimensional Kolmogorov power-law scaling. This is an ideal dusty plasma apparatus where we can create or move the dust cloud to a location of choice from the glass surface to in-between the electrodes and excite one among many collective dust dynamics.

Shifting Emphasis from Electro- to Catalytically Active Sites: Effects of Pore Size of Flow-Through Anodes on Water Purification.

A flow-through anode has demonstrated high efficiency for micropollutant abatement in water purification. In addition to developing novel electrode materials, a rational design of its porous structure is crucial to achieve high electrooxidation kinetics while sustaining a low cost for flow-through operation. However, our knowledge of the relationship between the pore structure and its performance is still incomplete. Therefore, we systematically explore the effect of pore size (with a median from 4.7 to 49.4 μm) on the flow-through anode efficiency. Results showed that when the pore size was <26.7 μm, the electrooxidation kinetics was insignificantly improved, but the permeability declined dramatically. Traditional empirical evidence from hydrodynamic modeling and electrochemical tests indicated that a flow-through anode with a smaller pore size (e.g., 4.7 μm) had a high mass transfer capability and large electroactive area. However, this did not further accelerate the micropollutant removal. Combining an overpotential distribution model and an imprinting method has revealed that the reactivity of a flow-through anode is related to the catalytically active volume/sites. The rapid overpotential decay as a function of depth in the anode would offset the merits arising from a small pore size. Herein, we demonstrate an optimal pore size distribution (∼20 μm) of typical flow-through anodes to maximize the process performance at a low energy cost, providing insights into the design of advanced flow-through anodes in water purification applications.

A comprehensive study on the overall performance of aluminum-air battery caused by anode structure

Aluminum-air (Al-air) battery has been regarded as one of the most promising next-generation energy storage devices. In this work, simulation and experimental were both employed to investigate the influence of porous anode structure on discharge performance of Al-air battery. The structure of the aluminum anode was modeled from the pore size of the aluminum anode based on the porous electrode theory.This study was the first work to focus on this point as far as we know. The simulation results revealed that the variation of the pore size of the circular hole affected the discharge performance of the aluminum-air cell and the discharge voltage increased with the increase of the pore size. To further verify the validity of the simulation data, we carried out experiments to verify the characterization of the self-corrosion rate, electrochemical properties and discharge performance of the aluminum anode based on the 3D printing process on the basis of improving the aluminum alloy powder molding quality. The testing results showed an agreement with the simulation analysis results. The minimum discharge voltage was 1.50 V when the circular hole aperture size was 2.0 mm, and the discharge voltage increased by 4.0% and 6.0% for the structured anodes with aperture sizes of 3.0 mm and 4.0 mm, respectively. The results gained in this work provide a novel method for other researchers to further improve the overall performance of aluminum-air batteries.

A 256 channel photon counting module using a square microchannel plate PMT in a tight packing envelop achieving

Photek have developed a square microchannel plate (MCP) photomultiplier tube (PMT) using 6 μm pore MCPs to achieve superior timing, compared to the previous generation which used 15 μm pores. The native anode pattern is 64 × 64, but for this module the pattern is ganged to a 16 × 16 design using an epoxy bonded PCB giving an anode size of 3.3 × 3.3 mm in a 53 × 53 mm active area. The electronic front-end is the TOFPET2d ASIC from Petsys Electronics, a combined amplifier/discriminator/TDC with 30 ps time bins and capable of 480 kHz per channel count rate, with sufficient dynamic range to allow for the gain variation inherent in large area MCP-PMTs. The outer envelope of the combined PMT and electronic front-end package allows for close packing on 4 sides with outer dimensions of 60 × 62 mm giving a 76% fill factor. We present results showing the combined performance of the PMT and TOFPET2d ASIC and the uniformity of single photon timing accuracy.

Graph Ordering Attention Networks

Graph Neural Networks (GNNs) have been successfully used in many problems involving graph-structured data, achieving state-of-the-art performance. GNNs typically employ a message-passing scheme, in which every node aggregates information from its neighbors using a permutation-invariant aggregation function. Standard well-examined choices such as the mean or sum aggregation functions have limited capabilities, as they are not able to capture interactions among neighbors. In this work, we formalize these interactions using an information-theoretic framework that notably includes synergistic information. Driven by this definition, we introduce the Graph Ordering Attention (GOAT) layer, a novel GNN component that captures interactions between nodes in a neighborhood. This is achieved by learning local node orderings via an attention mechanism and processing the ordered representations using a recurrent neural network aggregator. This design allows us to make use of a permutation-sensitive aggregator while maintaining the permutation-equivariance of the proposed GOAT layer. The GOAT model demonstrates its increased performance in modeling graph metrics that capture complex information, such as the betweenness centrality and the effective size of a node. In practical use-cases, its superior modeling capability is confirmed through its success in several real-world node classification benchmarks.

Influence of Electrodes Configuration on Hydraulic Characteristics of Constructed Wetland–Microbial Fuel Cell Systems Using Graphite Rods and Plates as Electrodes

Constructed wetland–microbial fuel cell coupling systems (CW–MFCs) have received significant academic interest in the last decade mainly due to the promotion of MFCs in relation to pollutants’ degradation in CWs. Firstly, we investigated the effect of hydraulic retention time (HRT) and electrode configuration on the flow field characteristics of CW–MFCs using graphite rods and plates as electrodes, as well as the optimization of electrode configuration using computational fluid dynamics (CFD) numerical simulation. The results showed that: (1) the apparent HRT was the most influential and decisive factor, with a contribution of over 90% for the average HRT of CW–MFCs; (2) anode spacing was the most influential factor for the hydraulic performance of CW–MFCs, with contributions of over 50% for water flow divergence and hydraulic efficiency (λ) and over 45% for effective volume ratio (e); (3) anode size was significant for e and λ, with a contribution of over 20%; (4) cathode position and cathode size had no statistically significant effect on the hydraulic performance of CW–MFCs. It was mainly through the blocking of water flows, flows around, compressing water flow channels and boundary layer separation that the MFC electrodes influenced the hydraulic characteristics of the flow field in CW–MFCs. Optimizing the flow field by optimizing the electrode configuration helped to facilitate electricity generation and pollutants’ removal in CW–MFCs. This study offers a scientific reference for improving the hydraulic performance of CW–MFCs, and it also provides a new research perspective for improving the wastewater treatment and electricity production performance of CW–MFCs.

Compressed Zero-Knowledge Proofs for Lattice-Based Accumulator

Abstract The lattice-based cryptographic accumulators, which enable short zero-knowledge arguments of membership, have numerous applications in post-quantum privacy-preserving protocols. However, most efficient quantum-safe zero-knowledge arguments are PCP-based systems and rely on non-falsifiable assumptions. For non-PCP-based constructions using the state-of-the-art techniques on compressing lattice-based zero-knowledge proofs, the concrete size of the resulting proof for accumulators with $2^{32}$ members is at least 500 KB. In this paper, we propose a compact non-PCP zero-knowledge proof for the lattice-based Merkle-tree, which leads to an efficient post-quantum cryptographic accumulator. The complexity of our construction is logarithmic in $l\cdot n_{s}$, where $l$ and $n_{s}$ denote the depth of the underlying Merkle-tree and the size of a node, respectively, and the concrete size is only $143.7\ $KB when $l=32$. In particular, we provide an improved lattice-based Bulletproof with efficient knowledge extraction, which allows large challenge space but small soundness slack. Furthermore, the amortized technique can be applied to the Bulletproof without breaking the knowledge soundness due to our improved knowledge extraction. As a direct application, we present a practical lattice-based ring signature, which can achieve logarithmical signing/verifying computational complexity with the number of the ring, while the state-of-the-art constructions (CRYPTO 21) have linear computational complexity.

Analysis of Effect of Ground Experiment Environment on Plasma Contactor Performance

The large difference in the working performance of a hollow cathode plasma contactor between the ground and actual on-orbit environments will cause difficulties in selecting a ground-test schemes to fully simulate the contactor real on-orbit characteristics. In this study, the effect of the simulated anode size and structure, the simulated anode surface state, the flow rate of background working gas, and the background plasma density on the emission characteristics and plume structure of the contactor are studied. Three self-made simulated anodes of different sizes and structures are applied in the ground experiments. The change of anode surface state (particularly the ability of absorbing electrons) is realized by dividing the self-made simulated anodes into four double-separated regions and alternatively electrically isolating them. An additional gas channel and an auxiliary contactor are used to create background working gas and a low-Earth-orbit plasma atmosphere, respectively. The voltage–current curves as well as the plasma parameter distributions at the contactor exit and in the far-field regions are determined under different regimes and working conditions. The relationship between the contactor’s emission characteristics and plume structure is clarified. The experimental results could provide useful information for instructing the contactor design and developing a real on-orbit experiment plan.

Enhancement of microbial fuel cell performance using pure magnesium anode

MFCs (Microbial Fuel Cell) are bio-electrochemical devices that use microorganisms as biocatalysts to transform the chemical energy found in organic or inorganic compounds into electric currents. However, one of the limitations of this technology in terms of practical application is its lower electric efficiency, which greatly depends on the selection of anode material and the types of waste water used. In this work, organically rich wastewater and pure magnesium anode materials were utilized. Also, to investigate the effect of electrode size on power generation, five different sizes of coin-shaped anodes were employed for the variation in anode size, whose diameter and thickness were (15 mm × 2 mm), (20 mm × 2 mm), (20 mm × 3 mm), (20 mm × 4 mm), and (25 mm × 2 mm) with corresponding surface areas [2πr(r+h)] are 448 mm 2, 754 mm 2, 817 mm 2, 880 mm 2 and 1139 mm 2, respectively. The maximum obtained current density, power density, and energy densities were 4734.26 mA/m2, 37400.625 mW/m2 and 81.59 kW-h/kg respectively, by the smallest anode of size (15 mm × 2 mm). This investigation showed that a reduction in the size of the anode decreases the loss in the activation zone. As a result, from the smallest anode, maximum power and energy output were obtained. Finally, this analysis outlines the process and approaches for MFC to produce more power at a potentially lower cost. It is noted that same waste water has been used throughout the study where surface area of the samples vary from lowest to highest level.

Surface-controlled sodium-ion storage mechanism of Li4Ti5O12 anode

Sodium-ion batteries (SIBs) are the promising candidate in grid systems owing to the wide distribution and abundance of sodium resources. However, the charge storage mechanism and size-effect of the active materials for SIBs remain largely unexplored. Herein, we synchronously investigate the electrochemical properties and structural evolutions of Li4Ti5O12 (LTO) anode for Li+ and Na+ storage, along with the nano-size effect on their charge storage behaviors. Through detailed kinetic analysis, it is found the Li+ storage in LTO is diffusion-controlled in bulk and shows increased surface-controlled contributions when the size is reduced to 18 nm. In comparison, for the Na+ storage, the domination step is surface-controlled in all the sizes of LTO from 260 to 18 nm, with over 55% contribution even at the low sweep rate of 0.1 mV s−1. The limited near-surface reaction region and low diffusion kinetics determine the surface-controlled Na+ storage behaviors and the specific capacities. The suitable size of LTO-18 nm anode displays a high capacity of ∼140 mAh g−1 (at 0.05 A g−1, ∼0.29C), high-rate capability (42 mAh g−1 at ∼57C), and long-term cycling stability (over 1200 cycles). Our finding provides insights into a precise design of nanomaterials for high-power sodium-ion storage devices.

Designing the 3D Porous Anode Based on Pore Size Dependent Li Deposition Behavior for Reversible Li Metal-Free Solid-State-Batteries

Li metal-based all-solid-state batteries (ASSBs) can potentially combine the high energy of Li metal anodes and the safety of ASSBs. Among Li metal-based ASSBs, lithium-free or anodeless ASSBs are considered optimal battery configurations because of their higher energy density and economic advantages attributed to the absence of Li metal during the battery assembly process. Despite the extensive interest in Li-free ASSBs, they continue to suffer from low Coulombic efficiency and poor cycle performance. One reason for this inferior performance is the unstable interface between the current collector and solid electrolyte (SE), which can eventually lead to inhomogeneous Li deposition, dendritic Li growth, and internal short circuits. Various approaches including 3D porous anodes have been proposed to control the Li deposition behavior and improve the reversibility of anodeless ASSBs; however, there is no clarity on the mechanism and conditions for determining the Li deposition behavior in this emerging system.In this study, we systematically investigate the Li deposition behavior depending on the pore size of 3D anode and successfully demonstrate the strategy to obtain a highly reversible 3D porous anode for Li-free ASSBs. We found that more Li deposits could be accommodated within the pores of the anode with a smaller pore size using stacked Ni particles as the Li-hosting porous anode; this implies that the Li movement into the anode occurs via diffusional Coble creep. We proposed the modification of the Ni surface with carbon coating and Ag nanoparticle decoration (Ni_C_Ag particles) to further improve the Li storage capacity of the Ni-based 3D anode and, thereby, secure the interfacial contact between the 3D Ni anode and SE. The resulting Ni_C_Ag 3D anode successfully accommodated the entire Li deposit of 2 mAh cm−2 within the porous architecture without the separation of the anode/SE interface. We clarified the improved Li storage capacity of the Ni_C_Ag anode as follows.(1) C and especially Ag electrochemically react with Li ions above 0 V; thus, Li ions can be transported to 3D Ni_C_Ag porous anode before Li deposition at the SE/anode interface at < 0 V. Further, the high Li ion diffusion coefficient of lithiated carbon and Li-Ag alloy can further reduce Li ions within the pores of the 3D anode; therefore, Li deposition can occur within the porous 3D Ni anode.(2) Lithiophilic C and Ag facilitated the movement of Li via diffusional Coble creep. In particular, Ag with solid solubility in Li (Li(Ag)) can significantly enhance Li adatom mobility because of the identical structure of Li(Ag) with pure Li.(3) Li(Ag) is widely known to lower the energy barrier for Li nucleation.With the significantly reduced nucleation overpotential and interfacial resistance, the Ni_C_Ag anode showed high reversibility in Li deposition and stripping. The Ni_C_Ag anode could be cycled for more than 60 and 100 cycles with Li3PS4 and Li6PS5Cl0.5Br0.5 SE in half cells with a capacity limit of 2 mAh cm−2 and a current density of 0.5 mA cm− 2maintaining the CE of 97.9% and 96.9 %, respectively. Further, the synergistic effects of the stable anode/SE interface and reduced nucleation energy barrier enable stable NCM full-cell cycling at a room temperature of 30 °C. The NCM811 cathode/Ni_C_Ag anode full cell in the Li-free configuration showed an initial areal discharge capacity of 2 mAh cm−2, and it operated stably with a CE of 99.47% for 100 cycles. Figure 1

Effect of plasma boundary and electrode asymmetry in planar DC discharge system

This paper present presents a detailed characterization and analysis of plasma formation using different anode sizes in two contrasting configurations in a planar DC discharge system. One configuration has a conducting boundary (CB) formed by the conducting wall of the vacuum chamber that acts as an extended cathode. The second configuration, the Small Volume Insulated Boundary (SVIB) with a volume 22.5 times smaller than the CB system, is realized by confining the plasma completely within a fully insulating boundary. Anode sizes may be equal to the cathode size (symmetric electrodes) or smaller (asymmetric electrodes). In general, CB discharges require much lower applied voltages, showing very little variation with the pressure. Although the symmetric CB discharges have only single electron population, the asymmetric electrode discharges exhibit two electron populations, a high-density bulk population (Te ∼ 2–3 eV) and a very low-density warm population (Tw ∼ 40 eV) that serves to enhance ionization and compensate for reduced anode size. In contrast, the SVIB discharges require high voltages, show considerable variation in discharge voltage both with pressure and anode size, and have higher densities. In addition, one finds two electron populations for all anode sizes. From estimates of the anode sheath drop, it is possible to show that all CB discharges have an electron-rich anode sheath for all anode sizes. In contrast, the SVIB discharges exhibit ion-rich anode sheaths for all anode sizes, although for small-sized anodes and high pressures the sheaths transform to an electron-rich sheath.

Anion-kinetics-selective graphene anode and cation-energy-selective MXene cathode for high-performance capacitive deionization

Capacitive deionization (CDI) is one of the most promising energy-efficient technologies for water desalination, however its industrial translation is slow and impeded by limited electrosorption capacity, slow electrosorption rate and poor cycling stability. Herein we address the above challenges by developing and validating a new concept of unimpeded and selective full-cell anion-cation separation using custom-designed anion-kinetics-selective anode and cation-energy-selective cathode. Nanoporous graphene anode enables the selective anion kinetics, while cation selectivity on the functionalized MXene cathode is due to the difference in ion adsorption energy. These mechanisms are validated by electrochemical quartz crystal microbalance measurements. The finely-tuned balance between ion transport and adsorption causes unimpeded ion diffusion, leading to the higher electrosorption rates. These effects are guided by the atomistic and quantum chemistry simulations, and also confirmed experimentally by tuning the pore size of graphene anode and the functionalization of MXene cathode. The fabricated asymmetric CDI cell exhibits superior electrosorption capacity of 49 mg g−1 and high electrosorption rate of 2.92 mg g−1 min−1 in 5000 mg L−1 NaCl solution as well as excellent cycling stability (100 cycles), which are among the best of the current state-of-the-art CDI studies. These results demonstrate the design of advanced electrode materials for the effective control of ion kinetics and energies to achieve selective ion transport, thus providing new insights for a broader range of energy-related applications.

Towards sustainable wastewater treatment: Influence of iron, zinc and aluminum as anode in combination with salt bridge on microbial fuel cell performance

Microbial fuel cell (MFC) is a green technology and does not harm the environment. It can be used for wastewater treatment, hydrogen production and power generation. There are lot of avenues need to be investigated to increase the efficiency of MFC and in order to make it acceptable publicly. Efficiency of MFC depends on many factors. In this study, the influence of anode materials (Fe, Al and Zn), their sizes (12, 16 and 20 cm2) and shapes (square, rectangular and circular) were investigated on MFC efficiency. Dual chamber MFC setup was prepared in which Rhodobacter capsulatus was used as biocatalytic agent. Results revealed that Zn anode gave the highest voltage of 1.57 V with corresponding 0.23 A of current. Size of 20 cm2 of anode gave maximum voltage of 1.66 V with corresponding value of 0.08 A current, while anode size of 16 cm2 gave maximum current of 0.75 A with corresponding voltage of 1.65 V. Regarding their studied shapes, circular shape of anode gave the highest voltages of 1.70 V. Salt bridge played an important role in internal resistance of the fuel cell. The results were checked by changing the diameter and length of the salt bridge. The best results were noticed with 16 cm2 circular Zn anode and Fe as cathode. Salt bridge with 7.5 cm length gave the highest voltage of 1.65 V, while 4 gauge diameter salt bridge gave the highest current of 0.85 A.