## 10 Conclusions and Future Perspective
### Performance Check and Validation in Real-World Applications  
Extensive in situ testing under practical operating conditions, such as varying temperatures, humidity levels, and load cycles, will provide critical insights into the long-term performance and reliability of styrene-based proton exchange membranes (PEMs) and anion exchange membranes (AEMs). These tests are essential to evaluate how these membranes withstand real-world challenges, including thermal cycling, mechanical stress, and chemical degradation, which are common in fuel cell applications. By simulating dynamic operating environments, researchers can identify potential failure mechanisms, optimize membrane formulations, and develop strategies to enhance durability and efficiency. Additionally, testing under extreme conditions, such as high temperatures or low humidity, will help determine the operational limits of styrene-based membranes and ensure their suitability for diverse applications, from automotive fuel cells to stationary power systems.  
By addressing these future directions, styrene-based PEMs and AEMs hold the potential to revolutionize fuel cell technologies, making them more cost effective, durable, and sustainable. Their development could significantly reduce the reliance on expensive perfluorinated polymers like Nafion, lowering the overall cost of fuel cell systems. Furthermore, the tunable chemical structure of styrene-based membranes allows for the incorporation of functional groups that enhance proton or hydroxide ion conductivity, mechanical strength, and chemical stability. These advancements could enable the widespread adoption of fuel cells in various sectors, including transportation, portable electronics, and renewable energy storage. By contributing to the development of clean energy solutions, styrene-based membranes could play a pivotal role in the global transition towards decarbonization and a sustainable energy future, helping to mitigate climate change and reduce dependence on fossil fuels.  
**Supplementary Materials:** The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/batteries11040134/s1](https://www.mdpi.com/article/10.3390/batteries11040134/s1)]([https://www.mdpi.com/article/10.3390/batteries11040134/s1](https://www.mdpi.com/article/10.3390/batteries11040134/s1)), Table S1: Chemical Reactions in fuel cells.  
M.R.A.: writing--review and editing, conceptualization; A.Z.; methodology, investigation; H.S.: visualization, formal analysis; K.D.: data curation, validation; M.T.A.: software; Q.X.: supervision, resources, project administration, funding acquisition. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This work was fully supported by the grants from Jiangsu Natural Science Foundation (No. BK20231323), State Key Laboratory of Engines at Tianjin University (No. K2020-14), High-Tech Research Key Laboratory of Zhenjiang City (No. SS2018002).  
**Data Availability Statement:** The data are available on request. For further details, contact the corresponding author.  
**Conflicts of Interest:** The authors mutually decided on this article publication and there are no conflicts of interest.