*Article* **Ecological Performance Optimization of a High Temperature Proton Exchange Membrane Fuel Cell**

**Dongxu Li, Siwei Li, Zheshu Ma \*, Bing Xu, Zhanghao Lu, Yanju Li and Meng Zheng**

College of Automobile and Traffic Engineering, Nanjing Forestry University, Nanjing 210037, China; Ldx961203@163.com (D.L.); wesly.li@outlook.com (S.L.); xb18260078388@163.com (B.X.); L18252038553@163.com (Z.L.); njfulyj@163.com (Y.L.); mengzai19950929@163.com (M.Z.)

**\*** Correspondence: mazheshu@njfu.edu.cn; Tel.: +86-137-7665-9269

**Abstract:** According to finite-time thermodynamics, an irreversible high temperature proton exchange membrane fuel cell (HT-PEMFC) model is established, and the mathematical expressions of the output power, energy efficiency, exergy efficiency and ecological coefficient of performance (ECOP) of HT-PEMFC are deduced. The ECOP is a step forward in optimizing the relationship between power and power dissipation, which is more in line with the principle of ecology. Based on the established HT-PEMFC model, the maximum power density is obtained under different parameters that include operating temperature, operating pressure, phosphoric acid doping level and relative humidity. At the same time, the energy efficiency, exergy efficiency and ECOP corresponding to the maximum power density are acquired so as to determine the optimal value of each index under the maximum power density. The results show that the higher the operating temperature and the doping level, the better the performance of HT-PEMFC is. However, the increase of operating pressure and relative humidity has little effect on HT-PEMFC performance.

**Keywords:** high temperature proton exchange membrane fuel cell; exergy analysis; ecological analysis; ecological coefficient of performance
