串联微生物燃料电池的电压反转行为

Voltage Reversal Behavior during Stacking Microbial Fuel Cells in Series

微生物燃料电池是一种处理废水同时产电的具有广阔应用前景的新型水处理技术,其串联是产生更高电压的有效方法之一,但是会产生电压反转现象降低串联微生物燃料电池的性能。文章将二极管引入串联微生物燃料电池中以考察电压反转的行为。结果表明,不同的串联微生物燃料电池中均会发生电压反转。串联正向二极管的微生物燃料电池的电压反转行为与没有串联二极管的微生物燃料电池类似,但是前者仅仅发生在一个周期的结束阶段。这可能是因为电子流经二极管时被其消耗,从而减缓了电极电势的变化速率。当串联反向二极管时,电压反转发生在仅阴极端连接二极管的单体微生物燃料电池上,而且各单体电池的电压约为其对应的开路电压(0.75 V)。这表明,各个单体电池消耗电子的不平衡性和电极电势的变化是导致电压反转的直接原因。

Stacking microbial fuel cell（MFC） in series is an effective approach to provide higher voltage.However,voltage reversal（VR） adversely affects performance of the stacked MFCs.In this paper,diodes are introduced into three stacked MFCs so as to investigate the VR behavior and offer a diodes-based explanation of the VR.Results show that VR occurs in the different stacked MFCs systems.VR of the stacked MFCs with forward diodes happens in a similar pattern as that without diodes.However,it only happens at the end of a cycle.This can be analyzed that the resistance of the diodes consume a part of the flowing electrons and the speed of potential changes of the electrodes slows down.In the stacked MFCs with reverse diodes,VR happens in the unit MFC with reverse diodes at the cathode end only and the voltages of each unit MFC approximately equal their open circuit voltages.It implies that the imbalanced consumption of electrons in unit MFCs and the potential changes of specific electrode directly result in VR.An effective approach to avoid VR in stacked MFCs is to provide enough substrate for each unit MFC and allow consecutive electrons flowing in the circuit.