This paper is part of an effort to establish design parameters for glucose-fueled room temperature membraneless alkaline fuel cells as possible electricity suppliers for portable devices. We report experimental results for three characteristics of glucose-fueled room temperature membraneless alkaline fuel cells: 1) polarization curve, 2) power density as a function of current density, and 3) internal resistance. The internal resistance of the cell was measured by two independent experimental methods: “Voltage Divider” and “Current Interrupt”. The three characteristics were measured as a function of glucose concentration while maintaining the electrolyte, KOH, constant at 0.35 M. The results were compared with those reported for other room temperature Alkaline Fuel Cells fuelled with glucose and methanol. We found that the maximum power density has a value of 0.36 mW/cm2 at a current density of 1.44 mA/cm2 when glucose concentration is 0.22M. The “Voltage Divider” and “Current Interrupt” methods for measuring the internal resistance produced practically the same results. The resistivity of the electrolyte/fuel solution was estimated from internal resistance measurements. Resistivity was found to be linearly dependent upon glucose concentration; at a constant KOH electrolyte concentration of 0.35 M, the specific resistivity of 1 M glucose is 2.56 Ω·m. The power density obtained with Alkaline Fuel Cells fuelled with glucose is an order of magnitude smaller than that obtained for cells fuelled with methanol. More efforts should be invested in order to develop a practical glucose-fuelled fuel cell.

Open circuit voltage is an important parameter of fuel cells. Prior works have demonstrated that open cell voltages of alkaline fuel cells fueled with glucose reach saturation at high glucose concentrations (0.1M–1M). At low concentrations, this voltage should increase logarithmically, according to the Nernst law. To study this reaction in the said fuel cells, open circuit voltages were measured over a wide concentration range. The fuel cell was operated as a continuous tank reactor undergoing a transient. During this transient, the concentration (either of glucose or KOH) of the solution in the fuel cell was decreased by several orders of magnitude. Measurements of voltage and concentration taken at different times tested their interdependence. Though no stirring was applied, the fuel cell behaves like a continuous stirred tank reactor. This was established by measuring concentration (either of glucose or KOH) versus time. The effect of concentration on the open circuit voltage was examined from 1.4M down to 0.001M for glucose and from 1M to 10−6M for KOH. The open cell voltage depends logarithmically on the glucose concentration at low glucose concentrations, up to 0.1M. From the Nernst law, it may be deduced that one electron is transferred by one glucose molecule to the anode. The open cell voltage is constant, 0.83V, at KOH concentrations from 1M down to 0.017M, dropping down to 0.52V at 10−6M KOH. Operating a fuel cell as a continuous stirred tank reactor is an efficient way of measuring fuel cell performance over a wide range of fuel and electrolyte concentrations. Analyzing the effect of concentration on cell voltage provides insight into the reaction mechanism.

The paper focuses on the conductivity of the fuel cell electrolyte in a membraneless glucose-fueled alkaline fuel cell. The electrolyte conductivity is interpreted using simple physical models, considering either the empirical behavior of the solution’s viscosity, or the consideration of ions and molecules colliding in solutions. The conductivity is expressed as a function of KOH and glucose concentrations. The physical properties of the species (i.e. radii, thermal velocity) and the chemical equilibrium constant of the reaction that glucose undergoes in an alkaline solution can be estimate by comparing the experimental results with the theory

An enzymatic glucose biofuel cell uses glucose as fuel and enzymes as biocatalyst, to transform biochemical energy into electrical energy. An analytical modelling of an enzymatic biofuel cell should be used, while developing fuel cell, to estimate its various enzymatic parameters, to obtain the highest voltage feasibly. The analytical model was developed, and the open circuit voltage (OCV) calculated by the model for various parameters of the fuel cell is in agreement with the experimental results. The OCV is interpreted by using this model, based on theoretical consideration of ions transportation in the solution. The generation and consumptions of the ions near the electrodes were defined in the model by exponential approximations, with different depletion coefficients. The model reveals that increasing the rates of hydrogen ions generation and (or) consumption by enzyme or chemical reactions leads to a higher value of OCV. The model points that the OCV is saturated with a glucose concentration and increased logarithmically with a surface enzyme concentration. Hence, a low glucose concentration is sufficient to obtain adequate OCV, on the one hand, but it can be increased by increasing electrode surface porosity, on the other hand. This model can be expanded to include time and close circuit voltage.

The electrical behavior of a room temperature membraneless Alkaline Fuel Cell, with incorporated platinum particles in the anode and fueled with glucose, is reported. The Open Circuit Voltage, at different initial glucose concentrations was measured. Changes on the glucose concentration with time were monitored with the dinitrosalicylic acid method. Qualitative Thin Layer Chromatography demonstrates that the electrodes induce polymerization of the glucose. The electrical yield of the system was measured with different external resistors. The Open Circuit Voltage reaches a saturation value of 0.78±0.03 V at [glu]0 > 0.67 M. During four hours in Open Circuit conditions, there is a 20% drop in the concentration of reducing sugar in the fuel cell. Thin Layer Chromatography experiments show that the electrodes catalyze non-electrochemical glucose polymerization reactions. Assuming that the glucose is oxidized to gluconic acid, the electrical yield of the system is around 5%.