Type and Future Trends of Type 01 Hydrogen Storage Tanks▣ Classification of Hydrogen Storage Tanks

　　Among numerous hydrogen storage technologies, high-pressure gaseous hydrogen storage stands out due to its fast hydrogen charging and discharging speed and simple container structure, making it the current mainstream hydrogen storage method. The core of this storage and transportation method is what we often call a hydrogen storage tank. Currently, vehicle-mounted hydrogen storage tanks are mainly divided into the following types:

　　Type I: Primarily made of all-metal structure, mostly steel.

　　Type II: Metal as the main body, supplemented by a circumferential fiber wrap. The material may be steel or aluminum, with added glass fiber composite material; in this type of hydrogen storage tank, the metal and composite material share the structural load.

　　Type III: Metal liner with an all-composite outer packaging, commonly aluminum, incorporating carbon fiber composite material; in this design, the composite material is responsible for the main structural load.

　　Type IV: All-composite structure, usually lined with polyamide (PA) or high-density polyethylene (HDPE) inside, and wrapped with carbon fiber or mixed carbon/glass fiber composite material outside; this type of hydrogen storage tank has its structural load entirely borne by the composite material.

　　Type V: Linerless design, all-composite structure, currently still under development.

　　With the rapid development and widespread industrialization of hydrogen fuel cells and electric vehicles, the storage and transportation of hydrogen has become a common concern for researchers worldwide. Among numerous storage and transportation methods, hydrogen storage tanks play a crucial role.

　　▣ Advantages of Type IV Hydrogen Storage Tanks

　　Currently, Type IV hydrogen storage tanks are attracting global attention due to their lightweight and durable characteristics, indicating that they will become the future leader in energy storage equipment for hydrogen fuel cell passenger vehicles. Currently, countries such as Japan, South Korea, the United States, and Norway have achieved mass production of Type IV hydrogen storage tanks, while other countries are actively planning to increase their research investment.

　　02 Structure and Materials of Type IV Hydrogen Storage TanksThe structure of a Type IV hydrogen storage tank can be summarized into the following three key parts:

　　First is the inner liner, with a wall thickness between 20 and 30 millimeters. The innermost layer is in direct contact with hydrogen and uses a gas barrier design to prevent hydrogen leakage. Its thickness is about 2 to 3 millimeters, and materials such as PA6, PA612, PA11, and HDPE are used, all of which have good barrier properties.

　　Next is the intermediate layer, which is mainly composed of CFRP carbon fiber reinforced composite material, including carbon fiber and epoxy resin. This layer is designed to ensure the pressure resistance level of the hydrogen storage tank while optimizing the thickness to improve hydrogen storage efficiency.

　　Finally, there is the outer layer, which also has a thickness of about 2 to 3 millimeters and uses GFRP glass fiber reinforced composite material, including glass fiber and epoxy resin. This design not only enhances the strength of the hydrogen storage tank but also helps maintain its lightweight characteristics.

　　▣ Inner Liner Material Selection and Manufacturers

　　As a key component of a hydrogen storage tank, the inner liner is mainly responsible for blocking hydrogen, so it has strict requirements for material properties, including hydrogen permeability resistance, heat resistance, excellent low-temperature mechanical properties, and good processing properties. Currently, nylon materials such as PA6, PA612, and PA11 are widely used in the market.

　　▣ Manufacturing Process of Type IV Hydrogen Storage Tanks

　　The inner liner of Type IV hydrogen storage tanks usually uses nylon 6, high-density polyethylene (HDPE), and PET polyester plastics. The molding processes for these materials mainly include injection molding, blow molding, and rotational molding. It is worth noting that the Type IV hydrogen storage tanks mass-produced by Toyota and Hyundai both use injection molding combined with welding. This process has relatively low costs and is widely used.

　　03 Innovation in Inner Liner Materials for Type IV Hydrogen Storage Tanks

　　▣ Development of Nylon Materials

　　As a key component of a hydrogen storage tank, the inner liner has strict requirements for material properties. PA6 material is selected as the inner liner material for hydrogen storage tanks due to its good mechanical properties, especially suitable for the inner liner manufacturing of Type IV hydrogen storage tanks. In addition, nylon 6 resin has shown excellent ability in preventing hydrogen permeation, and it also has excellent mechanical properties.

　　▣ Research and Application of New Materials

　　With the booming development of fuel cell vehicles, hydrogen storage tank suppliers have emerged like mushrooms after a spring rain, such as well-known companies like Toyota, Toyota Synthetic, the French company Faurecia, Norwegian Hexagon Purus, and South Korean Iljin Hysolus. Various manufacturers continue to introduce new materials to improve hydrogen storage tank performance and meet market demands, injecting new impetus into the development of the industry.