The article discusses the advancements and future directions in proton-exchange membrane fuel cell (PEMFC) technology, focusing on the critical challenge of increasing power density to achieve widespread commercialization. It highlights the ambitious goals set by organizations like Japan's New Energy and Industrial Technology Development Organization (NEDO) to reach 6 kW/l by 2030 and 9 kW/l by 2040. The paper outlines technical developments in the membrane electrode assembly (MEA) and its components, emphasizing improvements in water and thermal management and materials. Key areas of focus include the gas diffusion layer (GDL), catalyst layer (CL), proton-exchange membrane (PEM), and bipolar plates (BPs). The GDL's structural modifications, such as pore size gradients and integrated BP-MEA designs, are explored to enhance mass transfer and reduce resistance. The CL's performance is crucial for maximum power density, with novel catalyst architectures and carbon support modifications being key strategies. The PEM's role in proton conductivity and mechanical stability is also discussed, along with the challenges and advancements in BP design, including heat and electron conduction, durability, and cost reduction. The integrated BP-MEA design is proposed as a promising approach to achieve ultrahigh power density by improving compactness and eliminating interfacial transport resistances. Overall, the article emphasizes the interconnectedness of these components and the need for holistic development to meet the power density goals for next-generation PEMFCs.The article discusses the advancements and future directions in proton-exchange membrane fuel cell (PEMFC) technology, focusing on the critical challenge of increasing power density to achieve widespread commercialization. It highlights the ambitious goals set by organizations like Japan's New Energy and Industrial Technology Development Organization (NEDO) to reach 6 kW/l by 2030 and 9 kW/l by 2040. The paper outlines technical developments in the membrane electrode assembly (MEA) and its components, emphasizing improvements in water and thermal management and materials. Key areas of focus include the gas diffusion layer (GDL), catalyst layer (CL), proton-exchange membrane (PEM), and bipolar plates (BPs). The GDL's structural modifications, such as pore size gradients and integrated BP-MEA designs, are explored to enhance mass transfer and reduce resistance. The CL's performance is crucial for maximum power density, with novel catalyst architectures and carbon support modifications being key strategies. The PEM's role in proton conductivity and mechanical stability is also discussed, along with the challenges and advancements in BP design, including heat and electron conduction, durability, and cost reduction. The integrated BP-MEA design is proposed as a promising approach to achieve ultrahigh power density by improving compactness and eliminating interfacial transport resistances. Overall, the article emphasizes the interconnectedness of these components and the need for holistic development to meet the power density goals for next-generation PEMFCs.