Abstract:

This article investigates the status quo and research developments of carbon fiber reinforced materials in hydrogen storage and EV battery casings within the realm of new energy vehicles. It assesses the classifications and trends of high-pressure gas cylinders and battery enclosures, delves into the pros and cons of carbon fiber materials in their current uses, and foresees the applications and prospects of these advanced materials in the future landscape of new energy vehicles.

The shift towards lightweight materials to reduce the overall weight has become a key strategy in advancing the lightweighting of new energy vehicles. Progress in materials science has led to the adoption of various lightweight fiber composites, including glass and carbon fiber reinforced materials, in the new energy automotive industry.

Carbon fiber composites, renowned for their low density, high strength, corrosion resistance, and fatigue endurance, are among the most widely applied high-performance fiber composites in the automotive sector. Their applications span several vehicle systems, including the bodywork, engine, transmission, and chassis, enhancing vehicle performance and safety.

01 Carbon Fiber Overview

Carbon fibers are typically not used directly but as reinforcement, combined with resin, metal, or ceramic matrices to form carbon fiber composites. These fibers offer significant advantages: (1) low density and high strength, with a density of only 1.5~2.0 g/cm³, half that of light aluminum alloys, and 4~5 times the strength of steel and 6~7 times that of aluminum; (2) resistance to high and low temperatures, maintaining integrity in non-oxidizing atmospheres up to 3000°C and not becoming brittle at liquid ammonia temperatures; (3) excellent electrical conductivity, with a resistivity of 775 Ω·cm for high modulus carbon fibers and 1500 Ω·cm for high strength fibers at 25°C; (4) acid corrosion resistance, withstanding concentrated hydrochloric acid, phosphoric acid, sulfuric acid, etc.

Carbon fibers can be categorized based on precursor type, mechanical properties, and filament bundle size. In practice, classification often hinges on tensile strength and modulus, with high-strength types having strengths of 2000 MPa and moduli of 250 GPa, high modulus types exceeding 300 GPa in modulus, ultra-high-strength types surpassing 4000 MPa in strength, and ultra-high modulus types exceeding 450 GPa in modulus.

02 Application Status of Carbon Fiber Composites in the Automotive Field

The push for green energy and energy-saving measures has continually raised the bar for automotive lightweighting. According to the European Aluminium Association, a 10% reduction in vehicle weight can lead to a 6%~8% improvement in energy usage efficiency and a 10% reduction in pollutant emissions per hundred kilometers. For new energy vehicles, reducing the weight by 100kg can correspondingly increase their range by about 6%~11%.

Carbon fiber composites, known for their light weight and high strength, have found extensive application in vehicles, enhancing their performance and safety across various systems, including the bodywork, engine, transmission, and chassis.

03

Applications of Carbon Fiber Composites in Hydrogen Storage

With their high strength, corrosion resistance, fatigue resistance, flame retardancy, and dimensional stability, carbon fiber composites have become ideal substitutes for hydrogen storage in new energy vehicles and lightweight power battery enclosures.

3.1 High-Pressure Hydrogen Cylinder Application Scenarios

The use of high-pressure gas cylinders for hydrogen storage and release is a widely adopted method. Depending on the material, these cylinders are categorized into four types: entirely made of steel, steel liner with fiber wrapping, metal liner with fiber wrapping, and plastic liner with fiber wrapping. These varying structures and materials present different costs, maturity levels, and application scenarios.

Currently, carbon fiber reinforced materials are the mainstream material choice for manufacturing vehicular high-pressure hydrogen storage cylinders, despite facing challenges in technology and cost.

04

Applications of Carbon Fiber Composites in Battery Enclosures

The stability and safety of new energy power batteries have always been focal points in the industry. Battery enclosures, essential for protecting battery modules from external impacts, must meet requirements for corrosion resistance, insulation, and temperature resilience. Traditional battery enclosures are usually made from steel or aluminum alloys. However, with technological advancements, lightweight materials like carbon fiber composites are beginning to be employed, offering new possibilities for new energy vehicle development.

05

Conclusion

High-pressure gas cylinders with metal and plastic liners wrapped in fiber are the mainstream in current manufacturing technology. Carbon fiber, with its exceptional properties, shows great potential in the production of high-pressure gas cylinders and battery enclosures. However, due to cost constraints, widespread application of these advanced materials in battery enclosures is yet to be realized. As new energy technologies evolve and the cost of material applications decreases, carbon fiber composites are poised to play a significant role in the future.