Performance of a combined electrotrophic and electrogenic biofilm operated under long-term, continuous cycling

Objectives Evaluate electrochemically active biofilms as high energy density rechargeable microbial batteries toward providing persistent power in applications where traditional battery technology is limiting (, remote monitoring applications). Results Here we demonstrated that an electrochemically active biofilm was able to store and release electrical charge for alternating charge/discharge cycles of up to 24 h periodicity (50% duty cycle) with no significant decrease in average current density (0.16 ± 0.04 A/m 2 ) for over 600 days. However, operation at 24 h periodicity for > 50 days resulted in a sharp decrease in the current to nearly zero. This current crash was recoverable by decreasing the periodicity. Overall, the coulombic efficiency remained near unity within experimental error (102 ± 3%) for all of the tested cycling periods. Electrochemical characterization here suggests that electron transfer occurs through multiple routes, likely a mixture of direct and mediated mechanisms. Conclusions These results indicate that bidirectional electrogenic/electrotrophic biofilms are capable of efficient charge storage/release over a wide range of cycling frequency and may eventually enable development of sustainable, high energy density rechargeable batteries.