A potentially implantable glucose fuel cell with Raney-platinum film electrodes for improved hydrolytic and oxidative stability

We present an improved abiotically catalyzed glucose fuel cell, intended as energy harvesting tissue implantable power supply for medical implants. The fuel cell is constructed from a Raney-platinum film cathode deposited on a silicon substrate with micro-machined feedholes for glucose permeability, arranged in front of a Raney-platinum film anode. A novelty is the application of platinum for both electrodes and the complete abdication of hydrogel binders. This overcomes the limited stability against hydrolytic and oxidative attack encountered with previous glucose fuel cells fabricated from activated carbon particles dispersed in a hydrogel matrix. During performance characterization in phosphate buffered saline under physiological concentrations of glucose and oxygen the diffusion resistance to be expected from tissue capsule formation was taken into account. Despite the resulting limited oxygen supply, the Raney-platinum fuel cells exhibit a power density of up to (4.4 ± 0.2) μW cm⁻² at 7.0% oxygen saturation. This exceeds the performance of our previous carbon-based prototypes, and can be attributed to the higher catalytic activity of platinum cathodes and in particular the increased oxygen tolerance of the Raney-platinum film anodes.     

An abiotically catalyzed glucose fuel cell for powering medical implants: Reconstructed manufacturing protocol and analysis of performance

Although the first abiotically catalyzed glucose fuel cells have already been developed as sustainable power supply for medical implants in the 1970s, no detailed information concerning the fabrication of these devices has been published so far. Here we present a comprehensive manufacturing protocol for such a fuel cell, together with a detailed analysis of long-term performance in neutral buffer containing physiological amounts of glucose and oxygen. In air saturated solution a power density of (3.3 ± 0.2) μW cm⁻² is displayed after 10 days of operation that gradually decreases to a value of (1.0 ± 0.05) μW cm⁻² in the course of 224 days. A novelty of this work is the characterization of fuel cell performance with individually resolved electrode potentials. Using this technique, we can show that the major part of performance degradation originates from a positive shift of the anode potential, indicating that a more poisoning-resistant glucose oxidation catalyst would improve the degradation behavior of the fuel cell. As further factors influencing performance an incomplete reactant separation and a mass transfer governed cathode reaction under the relatively low oxygen partial pressures of body tissue have been identified. Consequently we propose an oxygen depleting electrode interlayer and the application of more effective oxygen reduction catalysts as promising strategies to further improve the fuel cell performance under physiological concentrations of glucose and oxygen.     

Synthesis and evaluation of Pt/rGO as the anode electrode in abiotic glucose fuel cell: Near to the human body physiological condition

In this research, abiotic catalyst 40 wt% Pt/rGO is successfully synthesized via chemical reduction method with an average particle size of 3 nm (characterized by TEM and XRD), and activity of it as anode catalyst for glucose oxidation is evaluated in phosphate-buffered saline (PBS, pH = 7.4) in the presence of 5 mM glucose (near-human body physiological concentrations).The fuel cell testing is carried out in a two-chamber abiotic glucose fuel cell (AGFC) utilizing Pt/rGO as the anode catalyst and PBS/glucose as the feed. Furthermore, effect of circulated fuel (based on human arm's vein blood flow rate, 0.33 mLs⁻¹) is also investigated for implantable purposes and is compared to stationary fuel; 10% increase in the AGFC voltage in contrast to 23% cell voltage drop respectively under 0.01 mAcm⁻² current density over 15 h. Results indicate that Pt/rGO is a promising catalyst for AGFCs to power implantable devices.     

Power sources and electrical recharging strategies for implantable medical devices

Implantable medical devices (IMDs) are critically requested for the survival of patients subject to certain serious diseases such as bradycardia, fibrillation, diabetes, and disability, etc. Appropriate working of an active implantable medical device (IMD) heavily relies on the continuous supply of electricity. In this sense, long-term powering and recharging of an IMD via a highly safe, efficient and convenient way is, therefore, extremely important in clinics. Several conventional batteries, such as lithium cell, nuclear cell and bio-fuel cell, etc., have been developed to power IMDs. Meanwhile, the recharge of IMD from outside of the human body is also under investigation. In this paper, some of the most typical IMD batteries are reviewed. Their advantages and disadvantages are compared. In addition, several emerging innovations to recharge or directly drive the implanted batteries, including electromagnetic energy transmission, piezoelectric power generation, thermoelectric devices, ultrasonic power motors, radio frequency recharging and optical recharging methods, etc., are also discussed. Some fundamental and practical issues thus involved are summarized, and future prospects in this area are made.     

A microfabricated low cost enzyme-free glucose fuel cell for powering low-power implantable devices

In the past decade the scientific community has showed considerable interest in the development of implantable medical devices such as muscle stimulators, neuroprosthetic devices, and biosensors. Those devices have low power requirements and can potentially be operated through fuel cells using reactants present in the body such as glucose and oxygen instead of non-rechargeable lithium batteries. In this paper, we present a thin, enzyme-free fuel cell with high current density and good stability at a current density of 10 μA cm⁻². A non-enzymatic approach is preferred because of higher long term stability. The fuel cell uses a stacked electrode design in order to achieve glucose and oxygen separation. An important characteristic of the fuel cell is that it has no membrane separating the electrodes, which results in low ohmic losses and small fuel cell volume. In addition, it uses a porous carbon paper support for the anodic catalyst layer which reduces the amount of platinum or other noble metal catalysts required for fabricating high surface area electrodes with good reactivity. The peak power output of the fuel cell is approximately 2 μW cm⁻² and has a sustainable power density of 1.5 μW cm⁻² at 10 μA cm⁻². An analysis on the effects of electrode thickness and inter electrode gap on the maximum power output of the fuel cell is also performed.     

High performance direct liquid fuel cells powered by xylose or glucose

In this work, we report the first abiotic, direct liquid fuel cells powered by the monosaccharide xylose using both a fully alkaline fuel cell (with anion exchange membrane) and a split pH fuel cell (with cation exchange membrane). We also report that the same fuel cells can be used with the monosaccharide glucose to produce much higher maximum power density than previously reported for abiotic, direct glucose fuel cells. This first alkaline direct xylose fuel cell (DXFC) produces a maximum power density of 57 mW cm⁻² at optimum conditions, while the split pH DXFC produces a maximum power density of 160 mW cm⁻². Our significantly improved alkaline direct glucose fuel cell (DGFC) produces 90 mW cm⁻² at optimum conditions, while the split pH DGFC produces 189 mW cm⁻². In addition to being high performing, these sugar molecules are naturally abundant, renewable, and known to convert to valuable products such as gluconic acid, glucaric acid, and xylonic acid during electrochemical oxidation. Other fuel cell and electrochemical cell data is also reported herein to understand the role of pH and fuel concentrations on behavior toward the electrochemical oxidation of these sugar molecules in alkaline media.     

All year power supply with off-grid photovoltaic system and clean seasonal power storage

The objective of the project is an all-year secure supply of alternating current based on a solar energy island grid consisting of serial components and seasonal energy storage. Photovoltaic modules, inverters, electrolysers, batteries, hydrogen stores and fuel cells form the basis of the independent power supply system. For this, selected load profiles were analysed and evaluated in theory and practice.The analysis is based on the results of the test runs of the system and the simulations, in which the combined hydrogen-battery-system is compared to the battery system.It was revealed that it is sensible to complement an island grid operating on lead batteries for shortterm energy supply with hydrogen as a long-term store. This ensures a year-round supply security based on solar energy and the extension of the life span of the batteries required for hydrogen-based power stores. The systems based purely on batteries can not provide perfect supply security during long periods of low solar radiation since they do not possess energy stores which allow long-term energy storage.Hence a seasonal energy store, such as hydrogen, is required to guarantee reliable power supply for every day of the year.Autonomous power supply systems with long-term energy stores operate independently from the public grid system and can be implemented without elaborate intelligent energy management. For this, however, the costs of the serial components must be reduced and the efficiency of the system must be improved.     

Hybrid cathode lithium batteries for implantable medical applications

Lithium batteries with hybrid cathodes of Ag₂V₄O₁₁ and CF_x have been developed that combine the best features of both cathode components. They can offer power density and energy density that are competitive with or superior to other developed battery chemistries, along with the stability and reliability needed for implantable medical applications. More than 100,000 have been used in human implants since introduction in 1999.     

The fuel cell electric vehicles: The highlight review

Transportation sector is the important sector and consumed the most fossil fuel in the world. Since COVID-19 started in 2019, this sector had become the world connector because every country relies on logistics. The transportation sector does not only deal with the human transportation but also relates to logistics. Research in every country has searched for alternative transportation to replace internal combustion engines using fossil fuel, one of the most prominent choices is fuel cells. Fuel cells can use hydrogen as fuel. Hydrogen can be fed to the fuel cells to provide electric power to drive vehicles, no greenhouse gas emission and no direct combustion required. The fuel cells have been developed widely as the 21st century energy-conservation devices for mobile, stationary, and especially vehicles. The fuel cell electric vehicles using hydrogen as fuel were also called hydrogen fuel cell vehicles or hydrogen electric vehicles. The fuel cells were misconceived by several people that they were batteries, but the fuel cells could provide electric power continuously if their fuel was provided continuously. The batteries could provide electric power as their only capacities, when all ions are released, no power could be provided. Because the fuel cell vehicles play important roles for our future transportation, the overall review for these vehicles is significantly interesting. This overall review can provide general and technical information, variety of readers; vehicle users, manufacturers, and scientists, can perceive and understand the fuel cell vehicles within this review. The readers can realize how important the fuel cell technologies are and support research around the world to drive the fuel cell vehicles to be the leading vehicles in our sustainable developing world.     

A study of the probabilistic risk assessment to the dry storage system of spent nuclear fuel

Due to the large power supply in the energy market since 1960s, the nuclear power planets have been consistently constructed throughout the world in order to maintain and supply sufficient fundamental power generation. Up to now, most of the planets have been operated to a point where the spent fuel pool has reached its design capacity volume. To prevent the plant from shutdown due to the spent fuel pool exceeding the design capacity, the dry cask storage can provides a solution for both the spent fuel pool capacity and the mid-term storage method for the spent fuel bundles at nuclear power planet.     

A mobile off-grid platform powered with photovoltaic/wind/battery/fuel cell hybrid power systems

Cross utilization of photovoltaic/wind/battery/fuel cell hybrid-power-system has been demonstrated to power an off-grid mobile living space. This concept shows that different renewable energy sources can be used simultaneously to power off-grid applications together with battery and hydrogen energy storage options. Photovoltaic (PV) and wind energy are used as primary sources and a fuel cell is used as backup power. A total of 2.7 kW energy production (wind and PV panels) along with 1.2 kW fuel cell power is supported with 17.2 kWh battery and 15 kWh hydrogen storage capacities. Supply/demand scenarios are prepared based on wind and solar data for Istanbul. Primary energy sources supply load and charge batteries. When there is energy excess, it is used to electrolyse water for hydrogen production, which in turn can either be used to power fuel cells or burnt as fuel by the hydrogen cooker. Power-to-gas and gas-to-power schemes are effectively utilized and shown in this study. Power demand by the installed equipment is supplied by batteries if no renewable energy is available. If there is high demand beyond battery capacity, fuel cell supplies energy in parallel. Automatic and manual controllable hydraulic systems are designed and installed to increase the photovoltaic efficiency by vertical axis control, to lift up & down wind turbine and to prevent vibrations on vehicle. Automatic control, data acquisition, monitoring, telemetry hardware and software are established. In order to increase public awareness of renewable energy sources and its applications, system has been demonstrated in various exhibitions, conferences, energy forums, universities, governmental and nongovernmental organizations in Turkey, Austria, United Arab Emirates and Romania.     

Fuel sensor-less control of a liquid feed fuel cell under dynamic loading conditions for portable power sources (II)

This work presents a new fuel sensor-less control scheme for liquid feed fuel cells that is able to control the supply to a fuel cell system for operation under dynamic loading conditions. The control scheme uses cell-operating characteristics, such as potential, current, and power, to regulate the fuel concentration of a liquid feed fuel cell without the need for a fuel concentration sensor. A current integral technique has been developed to calculate the quantity of fuel required at each monitoring cycle, which can be combined with the concentration regulating process to control the fuel supply for stable operation. As verified by systematic experiments, this scheme can effectively control the fuel supply of a liquid feed fuel cell with reduced response time, even under conditions where the membrane electrolyte assembly (MEA) deteriorates gradually. This advance will aid the commercialization of liquid feed fuel cells and make them more adaptable for use in portable and automotive power units such as laptops, e-bikes, and handicap cars.     

Model-based fault detection of hybrid fuel cell and photovoltaic direct current power sources

Hybrid DC power sources which consist of fuel cells, photovoltaic and lithium-ion batteries provide clean, high efficiency power supply. This hybrid DC power sources can be used in many applications. In this work, a model-based fault detection methodology for this hybrid DC power sources is presented. Firstly, the dynamic models of fuel cells, photovoltaic and lithium-ion batteries are built. The state space model of hybrid DC power sources is obtained by linearizing these dynamic models in operation points. Based on this state space model the fault detection methodology is proposed. Simulation results show that model-based fault detection methodology can find the fault on line, improve the generation time and avoid permanent damage to the equipment.     

Energy sources for the future dismounted soldier,the total integration of the energy consumption within the soldier system

At present, the energy supply for the electronic equipment of the soldier is problematic. Each component has its own battery pack. These battery packs are not interchangeable and each requires its own charger. Furthermore, because they are all dimensioned to deliver the peak power for each item of equipment, this leads to a higher battery weight than necessary.It is expected that the system of the future soldier will use a central power source to supply the energy for all the different components. An energy bus will be integrated within the soldier’s system for this. The different components will generate their required voltages from the bus voltage by using high efficiency dc/dc converters. The use of an energy bus with local voltage conversion will facilitate inter-operability between different forces. The energy sources can easily be exchanged.For the near future, batteries are still considered to be the best option for the energy source. Rechargeable batteries are preferred above non-rechargeable ones due to logistic and environmental problems. For the long-term replacement of batteries, the direct methanol fuel cell (DMFC) is considered a viable option.Several different battery packs were tested for their capability to supply both the required energy and power during a 24 h mission. The tests were carried out with a controlled power method, as maximum power should be deliverable during 10% of the operation time.     

Non-Pt catalyst as oxygen reduction reaction in microbial fuel cells: A review

Oxygen Reduction Reactions (ORR) are one of the main factors of major potential loss in low temperature fuel cells, such as microbial fuel cells and proton exchange membrane fuel cells. Various studies in the past decade have focused on determining a method to reduce the over potential of ORR and to replace the conventional costly Pt catalyst in both types of fuel cells. This review outlines important classes of abiotic catalysts and biocatalysts as electrochemical oxygen reduction reaction catalysts in microbial fuel cells. It was shown that manganese oxide and metal macrocycle compounds are good candidates for Pt catalyst replacements due to their high catalytic activity. Moreover, nitrogen doped nanocarbon material and electroconductive polymers are proven to have electrocatalytic activity, but further optimization is required if they are to replace Pt catalysts. A more interesting alternative is the use of bacteria as a biocatalyst in biocathodes, where the ORR is facilitated by bacterial metabolism within the biofilm formed on the cathode. More fundamental work is needed to understand the factors affecting the performance of the biocathode in order to improve the performance of the microbial fuel cells.     

Evaluation of hybrid and enzymatic nanofluidic fuel cells using 3D carbon structures

Membraneless nanofluidic fuel cells are devices that utilize fluid flow through nanoporous media which serve as three-dimensional electrodes. In the case of hybrid fuel cells (HFC) an enzymatic and an abiotic catalyst are incorporated on the electrodes. Here we compared two different HFC. In the first one (HFC-1), glucose oxidase- and Pt-based electrodes were used as bioanode and cathode respectively. This cell reached an open circuit voltage (OCV) of 0.55 V and a maximum power density of 5.7 mWcm^?2. In the second one (HFC-2), AuAg- and laccase-based electrodes were used as anode and biocathode respectively. This cell exhibited an OCV of 0.91 V and a maximum power density of 17 mWcm^?2. Finally, enzymatic electrodes were used to develop a high performance biofuel cell (3.2 mWcm^?2) that exhibited high stability over 4 days. These preliminary results indicate that the incorporation of enzymes into the 3D carbon structures is an efficient alternative for miniaturized nanofluidic power sources.     

Design and experimental tests of control strategies for active hybrid fuel cell/battery power sources

Twenty-first century handheld electronic devices and new generations of electric vehicles or electric airplanes have fueled a need for new high-energy, high-power, small-volume, and lightweight power sources. Current battery technology by itself is insufficient to provide the mandatory long-term power these systems require. Fuel cells are also unable to provide the essentially high peak power demanded by these systems. Hybrid systems composed of fuel cells and secondary batteries could combine the high power density of clean fuel cells and the high energy density of convenient batteries. This paper presents an experimental study on control strategies for active power sharing in such a hybrid fuel cell/battery power source. These control strategies limited the fuel cell current to safe values while also regulating the charging current or voltage of the battery. The several tested control strategies were implemented in MATLAB/Simulink and then tested under the pulsed-current load condition through experiments. Experimental tests were conducted with three control objectives: maximum fuel cell power, maximum fuel cell efficiency, and adaptive.     

太阳能光伏—燃料电池联合发电系统的模拟研究

叙述了为保证光伏发电系统长期、连续、稳定的电力供应构建的光伏—燃料电池联合发电系统及通过建立数学模型,利用Matlab模拟软件,进行不同配比电量输出和成本的仿真模拟结果,指出,通过调整系统的配比,可使蓄电池和H2罐的电量输出和成本达到最佳,提出,利用高效蓄电池只能满足短期的负载需求,用长寿命、低价格的H2罐,长时间存储电解的H2,在冬季光照不足时可用燃料电池满足负载需求.联合系统使二者互补,为用户提供长期、高效、连续、稳定的电力供给.     

Performance of Li-ion secondary batteries in low power,hybrid power supplies

Small, portable electronic devices need power supplies that have long life, high energy efficiency, high energy density, and can deliver short power bursts. Hybrid power sources that combine a high energy density fuel cell, or an energy scavenging device, with a high power secondary battery are of interest in sensors and wireless devices. However, fuel cells with low self-discharge have low power density and have a poor response to transient loads. A low capacity secondary lithium ion cell can provide short burst power needed in a hybrid fuel cell–battery power supply. This paper describes the polarization, cycling, and self-discharge of commercial lithium ion batteries as they would be used in the small, hybrid power source. The performance of 10 Li-ion variations, including organic electrolytes with Li_xV₂O₅ and Li_xMn₂O₄ cathodes and LiPON electrolyte with a LiCoO₂ cathode was evaluated. Electrochemical characterization shows that the vanadium oxide cathode cells perform better than their manganese oxide counterparts in every category. The vanadium oxide cells also show better cycling performance under shallow discharge conditions than LiPON cells at a given current. However, the LiPON cells show significantly lower energy loss due to polarization and self-discharge losses than the vanadium and manganese cells with organic electrolytes.     

Templating synthesis of hierarchically meso/macroporous N-doped microalgae derived biocarbon as oxygen reduction reaction catalyst for microbial fuel cells

N-doped carbons have been hailed as cost effective catalysts for the large-scale commercialization of microbial fuel cells (MFCs). In this paper, we developed a hierarchically meso/macroporous N-doped biocarbon by templating approach using Chlorella pyrenoidosa as precursor. The results showed that graphitic-N was the dominating functional group contributing to oxygen reduction reaction (ORR) performance. In addition, the role of pore structure was identified and the results suggested that mesopores exhibited a nearly linear correlation with limiting current density and half-wave potential, while electrochemical surface area almost linearly varied with macropores in the carbon materials. These results implied that mesopores play a dominating role in facilitating ion and oxygen supply and creating accessible active sites for ORR, while macropores mainly served as an electrolyte buffering reservoir shortening the electrolyte diffusion distances in the prepared catalysts. The optimized meso/macro pore structure enhanced the accessibility of the active sites and facilitated the mass transport of ion and oxygen, and consequently improved ORR performance of catalyst. The as-prepared catalyst exhibited a remarkably higher power generation than that of the commercial Pt/C in MFCs. This paper offered an insight into the effect of pore structure on the ORR performance of catalysts, and also provided an alternative avenue for synthesizing meso/macroporous carbon catalysts for the applications of MFCs.