Correlation of Overvoltages and Current Densities to Estimate Optimal Electrode Size for Sediment Microbial Fuel Cells

Abstract

We propose a method to determine the optimal electrode size of sediment microbial fuel cells (SMFCs). Four SMFCs presented a proportional increase in the current to the electrode size of the MFCs at day 16. From the I–V curves of the SMFCs, four plots of current versus electrode size (I–Esize plots) were obtained, which displayed high R2 values ranging from 0.980 to 0.994. At day 47, however, V–I curves deviated in one of the four MFCs, such that the I–Esize plots obtained from the I–V curves were inappropriate for estimating the electrode size. We found that the curves of overvoltage against the current density (η–j curves) were comparable in the SMFCs, suggesting that the overvoltage is inversely proportional to the electrode size of the MFCs. The I–Esize plots corrected by using the η–j curves had high R2 values of over 0.978, indicating that the η–j curves can be used for estimating the electrode size when the working voltage to current density ratio is different in SMFCs.

Serially Connectable Sediment Microbial Fuel Cells using Dipole Graphite Solids and Voltage Reversal Suppression

“…The charge pump works as as witch to connect or disconnectt he capacitora nd DC/DC converter. Thec apacitor is used to store the electrical energy produced by the SMFCs.T he voltage boostingl evel and period of time of the cycle to charge the capacitor of the PMS depend mainly on the voltage and electrical performanceo ft he SMFC.T od ate,h owever, the achievablep ower density of an individual SMFC is approximately 9-100 mW m À2 for aw orking voltage of 0.35-0.5 V, [14][15][16][17] which leads to al ong charging time of the PMS; therefore,e nhanced power density at high working voltages of SMFC system is desired.…”

“…The voltage boosting level and period of time of the cycle to charge the capacitor of the PMS depend mainly on the voltage and electrical performance of the SMFC. To date, however, the achievable power density of an individual SMFC is approximately 9–100 mW m −2 for a working voltage of 0.35–0.5 V, which leads to a long charging time of the PMS; therefore, enhanced power density at high working voltages of SMFC system is desired.…”