微生物燃料电池表观内阻的构成和测量

Composition and Measurement of the Apparent Internal Resistance in Microbial Fuel Cell

将微生物燃料电池内部各种阻力用表观内阻统一表征,在建立其等效电路的基础上将表观内阻分为欧姆内阻和非欧姆内阻2部分.通过稳态放电法测量微生物燃料电池表观内阻,在改变外电阻后稳定时间需要60 s以上方能保证测定准确性,通过稳态放电法测定一室型微生物燃料电池的表观内阻为289Ω,当外电阻等于表观内阻时微生物燃料电池对外输出功率达到最大,为241 mW/m2;通过电流中断法测量一室型微生物燃料电池的欧姆内阻为99Ω,测定结果与断电前电流强度无关;当一室型微生物燃料电池对外供电分别处于活化极化区、欧姆极化区和浓差极化区时,非欧姆电阻占总内阻的比例分别为93%、66%和75%,在电池对外供电达到最大时非欧姆占总内阻比例最低.提高微生物燃料电池产电能力需要同时降低电池的欧姆内阻和非欧姆内阻.

The electrochemical limitations on the performance of microbial fuel cells （MFCs） are mainly due to the internal resistance. The total resistance in the MFC was expressed as the apparent internal resistance （ Ri ） which was partitioned into ohmic resistance （ Rn ） and non-ohmic resistance （Rn）, referring to the equivalent circuit of the MFC. In the one-chamber MFC, Ri and Rn were measured using the steady discharging method and the current interrupt method, and they were 289 Ω and 99 Ω, respectively. The maximal power density was 241 mW/m^2 when the external resistance equaled to the apparent internal resistance. The stabilization time of 60 s was enough to remove the influence of the capacitors in the steady discharging method. When the MFC was in the activation overpotential area, the ohmic overpotential area and the concentration overpotential area respectively, Rn accounted for 93% , 66% and 75% in Ri . The ratio of Ro to Ri was the lowest when power output of the one-chamber MFC reached its highest value. Decreasing Rn and Rn is the key to one-chamber MFC＇ s output increasing.