Scaling up self-stratifying supercapacitive microbial fuel cell.

ABSTRACT: Self-stratifying microbial fuel cells with three different electrodes sizes and volumes were operated in supercapacitive mode. As the electrodes size increased, the equivalent series resistance decreased, and the overall power was enhanced (small: ESR = 7.2 ? and P max  = 13 mW; large: ESR = 4.2 ? and P max  = 22 mW). Power density referred to cathode geometric surface area and displacement volume of the electrolyte in the reactors. With regards to the electrode wet surface area, the large size electrodes (L-MFC) displayed the lowest power density (460 ?W cm-2) whilst the small and medium size electrodes (S-MFC, M-MFC) showed higher densities (668 ?W cm-2 and 633 ?W cm-2, respectively). With regard to the volumetric power densities the S-MFC, the M-MFC and the L-MFC had similar values (264 ?W mL-1, 265 ?W mL-1 and 249 ?W cm-1, respectively). Power density normalised in terms of carbon weight utilised for fabricating MFC cathodes-electrodes showed high output for smaller electrode size MFC (5811 ?W g-1-C- and 3270 ?W g-1-C- for the S-MFC and L-MFC, respectively) due to the fact that electrodes were optimised for MFC operations and not supercapacitive discharges. Apparent capacitance was high at lower current pulses suggesting high faradaic contribution. The electrostatic contribution detected at high current pulses was quite low. The results obtained give rise to important possibilities of performance improvements by optimising the device design and the electrode fabrication.

SUBMITTER: Walter XA 

PROVIDER: S-EPMC7491701 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature