Proton exchange membrane (PEM) is a key component of proton exchange membrane fuel cells (PEMFCs) and provides proton conduction between fuel and oxidant, and it is vitally important and practical to develop PEMs with high proton conductivity through membranes. However, it is still a major challenge to develop such membranes with high through-plane proton conductivity. In this study, Nafion composite membranes with sulfonated graphene oxides (SGOs) were prepared from self-assembly sol-gel either in or not in a strong magnetic field. Microstructures, water uptake, and proton conductivity of the SGO/Nafion composite membranes have been investigated extensively. For the SGO/Nafion composite membranes recast without a magnetic field, it is found that the water uptake and in-plane proton conductivity are greatly increased with the increasing SGO content. Interestingly, SGO/Nafion composite membranes with a low SGO content of ∼ 0.5 wt% exhibit lower crystallinity and higher in-plane proton conductivity. For the SGO/Nafion composite membranes recast in a strong through-plane magnetic field, it is very appealing to find their through-plane proton conductivity is significantly higher than that of the composite membranes recast without a magnetic field. This is attributed to that the protons transport in the membranes preferentially along the water channels primarily interconnected by the aligned SGOs through-plane induced by the strong magnetic field, as confirmed by SEM. Applied in a single PEMFC, the resultant SGO/Nafion composite membrane with 1 wt% SGOs, recast in a strong magnetic field of 1.5 T, demonstrates a high power-density of 1.056 W cm^-2, which is far superior to those of pristine Nafion and SGO/Nafion composite membranes recast without a magnetic field. The study provides a novel strategy for preparing proton exchanging membranes with high performances for new-generation fuel cells.

质子交换膜（PEM）是质子交换膜燃料电池（PEMFCs）的关键组成部分，在燃料和氧化剂之间提供质子传导，开发具有高质子传导性的质子膜质子交换膜具有重要意义和实用性。然而，开发这种具有高穿面质子电导率的膜仍然是一个重大挑战。在这项研究中，具有磺化氧化石墨烯 (SGO) 的 Nafion 复合膜是由自组装溶胶-凝胶在强磁场中或不在强磁场中制备的。SGO/Nafion复合膜的微观结构、吸水性和质子传导性已被广泛研究。对于无磁场重铸的 SGO/Nafion 复合膜，发现随着SGO含量的增加，吸水率和面内质子电导率大大增加。有趣的是，SGO/Nafion 复合膜的 SGO 含量较低，约为 0.5 wt%，结晶度较低，面内质子电导率较高。对于在强平面磁场中重铸的 SGO/Nafion 复合膜，发现它们的平面质子电导率明显高于没有磁场重铸的复合膜是非常有吸引力的。这归因于膜中的质子优先沿水通道传输，该水通道主要由强磁场诱导的对齐的 SGO 平面互连，如 SEM 所证实的。应用于单个 PEMFC，得到的 SGO/Nafion 复合膜具有 1 wt% SGO，^-2，远优于无磁场重铸的原始 Nafion 和 SGO/Nafion 复合膜。该研究为制备用于新一代燃料电池的高性能质子交换膜提供了一种新策略。