Investigation of PEMFC Stack Operating at Elevated Temperature

Hao Zhang,Jianxin Ma,Xiaoliang Zheng,Kan Tao,Daijun Yang

doi:10.3390/wevj4030481

Abstract

Proton exchange membrane fuel cell (PEMFC) operating at elevated temperature has many advantages compared to low temperature prototypes. With the adoption of short side chain, low equivalent weight (EW) perfluorosulphonic acid (PFSA) membrane, a 100W PEMFC stack was built and evaluated at an elevated temperature of 95℃. For the purpose of studying the effect of anode relative humidity (RH) on fuel cell performance, the stack was tested with (1) 60% RH air and 70% RH H2, (2) 60% RH air and dry H2, respectively under different temperatures. Furthermore, the CO tolerance of the stack was investigated at low and elevated temperatures in the presence of 5ppm, 10ppm and 20ppm CO/H2, respectively. The results demonstrated that the stack performance with dry H2 was more than 30% inferior to that with H2 of 70% RH, and the cell consistency deteriorated under higher temperature and lower anode RH. The polarization curves of the stack employed fuel rich in CO indicated that elevating the operating temperature to 95℃ could improve the anode catalyst tolerance to CO, and the CO poisoning effect on cell polarization is slight at low current densities.

Highlights

Proton exchange membrane fuel cell (PEMFC) usually works at 60-80°C
With the adoption of short side chain, low equivalent weight (EW) perfluorosulphonic acid (PFSA) membrane (Dongyue), the operating temperature of a 100W PEMFC stack was elevated to 95°C to evaluate the stack performance and tolerance to CO
The results demonstrate that elevating the operating temperature can effectively enhance the CO tolerance of PEMFC, for the CO absorption on Pt is an exothermic process, which means that the absorption favors low temperature, while increasing the temperature will have negative effect

Summary

Introduction

Proton exchange membrane fuel cell (PEMFC) usually works at 60-80°C. Some issues existing at low operating temperature can be alleviated by elevating the temperature [1-5]. Page000482 of great importance to develop polymer membranes capable of retaining high proton conductivity and possessing chemical and structural stability at elevated temperature. These developments could be classified into three groups [6-9]: (1) modified PFSA membranes, which incorporate hydroscopic oxides and solid inorganic proton conductors; (2) sulfonated polyaromatic polymers and composite membranes, such as PEEK, SPEEK, and PBI; (3) acid–base polymer membranes, such as phosphoric acid-doped PBI. The shorter side chain membranes, such as Dupont’s Nafion®-DFC1 and Solvay’s AquivionTM E79-03S are available on the market, which can be used up to 100°C [10] In this contribution, with the adoption of short side chain, low equivalent weight (EW) PFSA membrane (Dongyue), the operating temperature of a 100W PEMFC stack was elevated to 95°C to evaluate the stack performance and tolerance to CO

Stack preparation

Test conditions

Impact of anode relative humidity on stack performance

CO tolerance of the stack under different temperatures

Conclusions