Comparative evaluation of performance and electrochemistry of microbial fuel cells with different anode structures and materials

Abstract Various materials and anode structures have been applied to enhance MFC performance. However, their comparative evaluation of performance and electrochemistry has not yet been investigated in detail under a same condition. In this study, a carbon-cloth anode, an anode-cathode assembly, and a brush anode with two different orientations were tested under a same condition for comparative analyses on their performance and electrochemistry, in order to reveal their unique electrochemical characteristics. The brush anode cells exhibited better performance than the carbon cloth cells. The brush anodes showed 41–72% higher maximum power densities, 18–75% higher maximum current density and 24–32% higher optimum current densities than the carbon cloth anodes. The brush anodes showed 25–43 Ω lower anodic polarization resistance than the carbon cloth anodes. The brush anodes showed 1.6–21.2 Ω lower ohmic impedance, 7.7–10.6 Ω lower charge transfer impedance and 9.3–31.8 Ω lower anodic impedance than the carbon cloth anodes. Anodic ohmic impedance was greatest in the carbon-cloth-anode MFC (21.9 Ω), where loose contact between a carbon cloth and a current collector might cause the high ohmic resistance, and large solution resistance in the cell could diminish anode performance due to slow ion transport. In order to improve MFC performance by modifying anode structures, we suggest the followings: 1) an anode should have large surface area, 2) anodic carbon material and a metal current collector must be tightly connected, 3) locating a brush anode closer to a cathode can be important.