## 1 Introduction  
Fuel cell electric vehicles (FCEVs) are expected to play a crucial role in realizing a low-carbon transportation future within the burgeoning hydrogen economy. Proton exchange membrane fuel cells (PEMFCs), with their low emissions, high efficiency, and low-temperature operation, are gaining traction in the automotive industry. However, PEMFClifetime remains a critical challenge that must be overcome to achieve their widespread commercial viability. Over prolonged operation periods, performance deteriorates due to intricate operational conditions and component ageing, eventually reaching the minimum acceptable threshold [1]. The U.S. Department of Energy (DOE) has set ambitious durability targets for transportation fuel-cell systems. To be competitive with internal combustion engines and other alternatives, these systems must achieve over 8000 h of operation with less than a 10% performance loss [2]. Furthermore, for heavy-duty vehicles, the target is even more demanding, requiring over 25,000 h of durability by 2030 [3]. Achieving these durability targets under realistic automotive operating conditions necessitates lengthy and expensive testing procedures. Consequently, accelerated stress tests (ASTs) have emerged as a vital tool for rapidly assessing and predicting fuel-cell durability [4]. ASTs accelerate the degradation processes in fuel cells by intensifying operational stressors such as temperature [5], humidity [6], and load cycling. The DOE has established standardized AST protocols for various PEMFC components, including electrocatalysts, catalyst supports, membrane chemical/mechanical, and stack drive-cycles [7]. These tests are divided into two main categories: accelerated life tests (ALTs) and accelerated degradation tests (ADTs). ALTs operate fuel cells until failure, providing insights into degradation mechanisms. By contrast, ADTs leverage degradation data to predict the time to failure. ALTs have proven effective in identifying the root causes of performance degradation. For instance, [PERSON] et al. [5] demonstrated that increasing the temperature from room temperature to 80 \({}^{\circ}\)C accelerates membrane degradation owing to increased oxygen reduction reaction (ORR) activity and peroxide generation. Although ALTs are feasible for individual PEMFC components, their application to complete stacks is often impractical owing to the extended testing durations required. For example, Toyota conducted modified accelerated durability tests on 13-cell prototype fuel-cell stacks for commercial FCEVs, simulating 30,000 start-stop and 73,000 load cycles under realistic driving conditions. Despite meeting their target durability of 15 years and 200,000 km [8], with a cell-voltage drop of under 6% (at 2.2 A/cm\({}^{2}\)), assessing the ultimate lifetime requires more time. [PERSON] et al. [9] developed a Dynamic Accelerated Stress Test (AST) to evaluate the durability of fuel cell Membrane Electrode Assemblies (MEAs) for high-performance heavy-duty vehicles (HDVs). This test revealed that after 1000 h of accelerated aging, the maximum power density of the fuel cell decreased by about 10% from over 800 mW/cm\({}^{2}\), and the Electrochemical Surface Area (ECSA) decreased by about 25%. [PERSON] et al. [10] developed accelerated durability test protocols under realistic operating conditions. They performed a 5500 h evaluation on a reference stack and conducted four additional tests, each for 1200 h, focusing on various stress factors. These tests achieved an acceleration factor of 3-7 times, depending on the specific test. They particularly noted that relative humidity and temperature significantly influenced degradation. However, while these experiments accelerate the degradation of the fuel cell by increasing stress conditions, allowing for relative comparisons with existing stacks, accurately predicting the lifetime of fuel cells in real-world driving conditions remains a significant challenge.