Development of novel polyethylene air-cathode material for microbial fuel cells

Air-cathode fabrication is currently a key factor that hinders the scaling up of microbial fuel cell (MFC) technology. A new type of cathode material that contains porous polyethylene (PE) sheet and a blended activated carbon (AC) and highly conductive carbon back (CB) layer was developed for the first time. The PE sheet functions as both gas diffusion layer (GDL) and cathode supporting material. The blended AC and CB layer eliminates expensive current collector. Among different types of PE sheets and AC and CB blending ratios, the cathode with Type I PE sheet (75-110 μm pore size) and a CB/AC ratio of 1: 0.5 demonstrated the best performance (8.4 A m−2 at 0 V) in electrochemical cells. MFCs with this cathode generated more stable and higher power densities compared with those using PTFE cathodes. Simulation of ohmic potential drops across this cathode material suggests that using a two-parallel terminal connection design would result in only 0.04 V potential drop at 1 m2 scale. This study suggests that this new PE cathode material has great potential for use in scaled up MFC systems due to its decent performance, simple fabrication process, and use of low-cost material.