Search / Korean Journal of Chemical Engineering
HWAHAK KONGHAK,
Vol.31, No.6, 735-743, 1993
인산형 연료전지의 단위전지 운전 특성 연구
Operational Characteristics of Single Cell in Phosphoric Acid Fuel Cell
인산형 연료전지 단위전지를 제조하여 연속운전시 성능 특성을 oxygen gain법과 교류 임피던스법을 이용하여 조사하였으며, 또한 반응기체의 공급중단시 성능 저하요인을 분석하였다. 단위전지는 약 4,500시간 동안 연속 운전되었으며, 전지의 성능은 운전시간이 증가함에 따라 평균 19.7mV/1,000hr의 저하속도로 감소하였다. 단위전지 운전초기에는 확산과정에 비해 활성화 영역이 전극반응을 지배하였으며, 이 시기에서의 전지성능 저하요인은 산소극의 계면저항과 전지내부저항의 증가에 기인하는 것으로 나타났다. 운전 후기에는 확산 지배영역이 우세하게 나타났으며, 이 때 운전시간의 증가는 oxygen gain을 크게 증가시킨다는 사실을 확인하였다. 또한 반응기체 공급중단시 산소기체의 공급중단에 비해 수소기체의 공급중단이 전지성능을 크게 저하시켰다. 연속운전에 따른 단위전지의 성능저하에 관한 이러한 실험결과를 산소극의 3상계면 특성과 전극의 퇴화와 관련시켜 고찰하였다.
Operational characteristics of single cell in phosphoric acid fuel cell(PAFC) have been studied using oxygen gain and AC impedance methods. Also effect of reactant gas starvation on PAFC performance was examined. The single cell was operated for 4,500hr at the average performance decay rate of 19.7mV/1,000hr. At the operation time below 1,000hr the activation precess was dominant over the cell electrode reaction and then the decreased cell performance is due mainly to an increased internal resistance of the cell and an increased interfacial resistance of the oxygen electrode. At the operation time above 2,000hr, the oxygen gain was larger than a theoretical value of the activation-diffusion mixed process, which indicates that the cell decay at long run resulted from the slow diffusion process. In addition the hydrogen starvation showed more cell performance loss than the oxygen starvation due probably to carbon corrosion. These results were discussed as related to the oxygen electrode reaction at three phase boundary of the electrode and the degradation of the electrode components.
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