Multi‐Scale Evaluation of Novel Alternating Carbon Fiber–Polyethylene Hybrid Laminates Reinforced With Graphene Nanoplatelets for Linerless Type‐V Hydrogen Storage Vessels

Type‐V composite pressure vessels (CPVs) for hydrogen storage face challenges in balancing high structural strength, lightweight construction, and permeation‐barrier performance. In this study, hybrid 4 carbon and 3 polyethylene (4C3PE) laminates alternating reinforced with graphene nanoplatelets (GNP) are prepared. A comparative multi‐scale analysis was conducted for Type‐V laminate architectures, integrating analytical hoop‐stress, finite element analysis (FEA) simulations, and ASTM D3039 tensile experiment analysis to develop a reliable design framework. Experimental characterization of the 4C3PE laminate revealed that a 2 wt.% GNP loading provides an allowable ultimate tensile strength of 648 MPa, with uniform dispersion of GNPs of an average agglomerate size (0.42 ± 0.11 μm), and a low void content below 1.5%. The carbon fiber‐polyethylene interlayers function as compliant barriers, reducing interlaminar shear stresses and preventing microcrack propagation. Structural scaling studies indicate that the 4C3PE architecture with unidirectional (0/0/0) s stacking sequences is unsafe under 70 MPa pressure for configurations under 12C11PE. The 16C15PE laminate, as the optimal design, achieves a balanced Factor of Safety of 3.11 by maintaining circumferential stresses at 208.605 MPa within allowable limits, despite the weight penalties associated with thicker laminates. Microstructural observations suggest that GNP‐assisted crack deflection, PE‐mediated delamination suppression, and the formation of tortuous diffusion pathways may reduce potential hydrogen‐permeation routes. The study establishes a framework for screening materials in laminated architectures, with the 16C15PE laminate and 2 wt.% GNP as a promising candidate for linerless Type‐V vessels. This groundwork will facilitate future tests on pressure‐cycling and hydrogen permeability for full‐scale vessel production.