Rechargeable microbial fuel cell based on bidirectional extracellular electron transfer

Rechargeable microbial electrochemical systems can be used as renewable energy storage systems or as potable bioelectronics devices. In this study, a bioelectrode capable of bidirectional extracellular electron transfer was firstly introduced to construct the rechargeable microbial fuel cell (MFC). The performance of rechargeable MFC was enhanced with the increase of charge/discharge cycles, and a maximum energy efficiency of 4.5 ? 0.2% and Coulombic efficiency of 29.4 ? 4.1% were obtained. H2 was the main charge carrier, while the accumulated acetate was only about 10 mg L-1. The charge time under constant current mode largely affected the energy recovery. A decreased abundance of Mycobacteria, Geobacter, and Azospirillum, accompanied by an increase of Azonexus and Rhodococcus was observed in the rechargeable MFC, compared to control tests fueled with acetate. This study demonstrates the potential of bioelectrode for energy storage and recovery.

Automated summary

Rechargeable microbial fuel cells, utilizing bidirectional extracellular electron transfer bioelectrodes, showed improved performance with increasing charge/discharge cycles, achieving high energy efficiency and Coulombic efficiency. H2 was the primary charge carrier while acetate accumulation was minimal. Charge time under constant current mode significantly impacted energy recovery, and microbial communities in the rechargeable MFC differed from controls. This study highlights the potential of bioelectrodes for energy storage and recovery.