In-depth understanding of the effect of compression on the water management in polymer electrolyte fuel cells (PEFCs) is indispensable for optimisation of performance and durability. Here, in-operando neutron radiography is utilised to evaluate the liquid water distribution and transport within a PEFC under different levels of compression. A quantitative analysis is presented with the influence of compression on the water droplet number and median droplet surface area across the entire electrode area. Water management and performance of PEFCs is strongly affected by the compression: the cell compressed at 1.0 MPa demonstrates ∼3.2% and ∼7.8% increase in the maximum power density over 1.8 MPa and 2.3 MPa, respectively. Correlation of performance to neutron radiography reveals that the performance deviation in the mass transport region is likely due to flooding issues. This could be ascribed to the loss of the porosity and increased tortuosity factor of the gas diffusion layer under the land at higher compression pressure. The size and number of droplets formed as a function of cell compression was examined: with higher compression pressure, water droplet number and median droplet surface area rapidly increase, showing the ineffective water removal, which leads to fuel starvation and the consequent performance decay.

深入了解压缩对聚合物电解质燃料电池（PEFC）中水管理的影响对于优化性能和耐用性是必不可少的。在这里，操作中中子射线照相术被用来评估在不同压缩水平下PEFC内的液态水分布和传输。提出了定量分析，其中压缩对整个电极区域上的水滴数和中值液滴表面积产生影响。PEFC的水管理和性能受压缩的强烈影响：在1.0 MPa压缩的电池在1.8 MPa和2.3 MPa的压力下，最大功率密度分别提高了约3.2％和7.8％。性能与中子射线照相的相关性表明，在质量传输区域中的性能偏差很可能是由于洪水问题造成的。这可以归因于在较高压缩压力下在平台下的气体扩散层的孔隙率的损失和曲折系数的增加。检查了形成的液滴的大小和数量与细胞压缩的关系：在较高的压缩压力下，水滴数量和中值液滴表面积迅速增加，显示出无效的除水作用，这导致燃料不足并因此导致性能下降。