Review on linerless type V cryo-compressed hydrogen storage vessels: Resin toughening and hydrogen-barrier properties control

Cryo-compressed hydrogen (CcH₂) storage has significant advantages such as long dormancy, high safety factor, and rapid filling; thus, it is suitable for the energy supply of heavy-duty vehicles. Carbon fiber composites for state-of-the-art linerless type V CcH₂ storage vessels should have both pressure-bearing and hydrogen-barrier properties. However, these properties are difficult to achieve under cryogenic temperatures and high pressures. Resin failure is the main reason behind the degradation of cryogenic properties. In this work, methods to achieve resin toughening and hydrogen-barrier control are reviewed. Comparisons indicate that thermoplastics are more suitable for resin toughening than other materials, and that interlayer films can effectively block hydrogen permeation. Resins with added nanomaterials not only stop the propagation of microcracks but also generate tortuous paths within the composites to inhibit hydrogen permeation. However, the issues of temperature-induced strain and state regulation of nanomaterials must be further addressed. In this study, a resin film modified with toughening agents and nanomaterials was also designed. The film was then placed between carbon fiber plies. Hot-pressing and surface treatment of the resin film were performed to enhance the orientation of the nanomaterials and interlayer adhesion force. The proposed composite may be useful in the manufacture of linerless Type V CcH₂ storage vessels.