Advantages and Technological Progress of Hydrogen Fuel Cell Vehicles

1. Background

The automotive industry is undergoing a profound transformation driven by the need for sustainable and environmentally friendly transportation solutions [1]. In this context, fuel cell technology has emerged as a promising alternative, offering clean, efficient, and high-performance power sources for vehicles [2]. Fuel cell vehicles are electric vehicles that use fuel cell systems as a single power source or as a hybrid power source in combination with rechargeable energy storage systems. A typical fuel cell system for electric vehicle is exhibited in Figure 1, which provides a comprehensive demonstration of this kind of complex system. Hydrogen energy is a crucial field in the new energy revolution and will become a key pillar in building a green, efficient, and secure new energy system. As a critical field for hydrogen utilization, fuel cell vehicles will play an important role in the transformation and development of the automotive industry. The development of fuel cell vehicles offers numerous advantages such as strong power outputs, safety, reliability, and economic energy savings [3]. However, improvements must urgently be made in existing technologies such as fuel cell stacks (including proton exchange membranes, catalysts, gas diffusion layers, and bipolar plates), compressors, and onboard hydrogen storage systems [4]. The advantages and current technological status are analyzed here.

2. Advantages of Fuel Cell Vehicles

2.1. Strong Power Output

The power system of fuel cell vehicles adopts the “electric–electric hybrid” technology route, which combines the use of both a power battery and a fuel cell. The power battery, typically a lithium battery, provides high power for vehicle acceleration, deceleration, and other non-steady-state power demands, while the fuel cell is responsible for providing a stable power output under steady operating conditions. This solution not only solves the problem of slow dynamic responses in fuel cells but also greatly extends the lifespan of the fuel cell [5]. Additionally, it delivers a robust power output. For example, in the case of fuel cell urban buses, the maximum climbing gradient can reach 22% (compared to 20% for traditional buses under the same conditions), and the acceleration time from 0 to 50 km/h is only 8 s, while traditional buses require 30 s. This clearly demonstrates the superior acceleration capability of fuel cell vehicles compared to traditional vehicles.

2.2. Safety and Reliability

Through actual operations, fuel cell vehicles have demonstrated significantly longer operational times and mileages compared to pure electric vehicles, thus offering higher levels of safety. Both fuel cell passenger cars and commercial vehicles have longer operational times and mileages throughout their lifecycles compared to their pure electric counterparts. This indicates that fuel cell vehicles exhibit superior levels of durability and reliability compared to pure electric vehicles, making them safer and more reliable.

2.3. Economic Energy Savings

2.3.1. Low Total Cost of Ownership

Fuel cell vehicles have low energy consumption costs, and the total cost of ownership over the entire lifecycle (estimated to be 8 years) is much lower than that of traditional vehicles and pure electric vehicles. In particular, the fuel costs of fuel cell vehicles are significantly lower than those of traditional vehicles, aligning perfectly with society’s expectations for energy savings and emission reductions.

2.3.2. High Energy-Conversion Efficiency

Fuel cell vehicles achieve high energy-conversion efficiency. It is estimated that the energy conversion efficiency of their fuel cell stacks is 62%. When accounting for the energy consumption of a fuel cell engine’s auxiliary systems (16.4%) and the energy consumption of the motor and its drive system (8.1%), the overall efficiency from “tank to wheel” is 37.7%. This is far higher than the conversion efficiency of gasoline-powered vehicles (16% to 18%) and diesel-powered vehicles (20% to 24%).

3. Technological Status of Fuel Cell Vehicles

The power source of fuel cell vehicles is a fuel cell system, and the core technology lies in this fuel cell system. Therefore, the maturity of fuel cell system technology determines the development prospects of fuel cell vehicles. The current technological status of key components in the fuel cell system, including the fuel cell stack (including proton exchange membrane, catalysts, gas diffusion layers, and bipolar plates), compressors, and onboard hydrogen storage systems, is described below.

3.1. Technological Status of Fuel Cell Stacks

Currently, the advanced fuel cell stack technology that can be mass-produced has the following parameter levels: system power greater than 100 kW, power density exceeding 3.1 kW/L, cold start temperature reaching −30 °C, platinum loading as low as 0.115 g/kW, and durability ranging from 5000 to 20,000 h [5,6].

3.1.1. Proton Exchange Membrane Technology Status

To date, advanced ultra-thin reinforced proton exchange membranes have been developed, with the thinnest reaching 7–10 µm. These membranes exhibit excellent power density, mechanical durability, and self-humidification effects in water vapor diffusion. They have been proven capable of undergoing over 20,000 cycles of dry/wet conditions and have demonstrated good mechanical stability. They have been widely used in passenger vehicles. In the future, proton exchange membrane technology will tend to be film-based, which will help reduce proton transfer resistance and achieve higher performance.

3.1.2. Catalyst Technology Status

Currently, it is possible to mass-produce fuel cell catalyst technology. PV/C catalysts exhibit excellent overall performance and have been used in Honda fuel cell vehicles. PtCo/C catalysts have also begun to be used in trial operations in fuel cell vehicles. Due to the expensive and rare nature of Pt metal, the development of low-Pt and Pt-free catalysts will be a future research trend in fuel cell catalysts.

3.1.3. Gas Diffusion Layer Technology Status

The production process of gas diffusion layers has achieved roll-to-roll production, ensuring a stable and large-scale supply of high-performance products. These products have a thin substrate layer, and their microporous layers exhibit excellent gas permeability. Modifying carbon paper with chemically vapor-deposited (CVD) pyrolytic carbon can produce unique-shaped carbon paper structures that are highly adaptable to deformation mechanisms. By combining dry forming, CVD, catalytic carbonization, and graphitization in a continuous production process, the durability and stability of the products can be further enhanced. In the future, carbon paper technology will trend toward film-based structures to improve gas diffusion capacity and reduce mass transfer issues at high current densities.

3.1.4. Bipolar Plate Technology Status

Currently, the industry has developed a relatively mature industrial chain for bipolar plates, with mature industrialization systems being established in manufacturing processes, quality control, cost management, and mass production. Among them, the core technologies of metal bipolar plates, such as plate design, precision manufacturing, and corrosion-resistant coatings, are considered essential for dominating the high ground of fuel cell technology. Nano-composite coatings, such as graphite-based and titanium–chromium-based coatings, can significantly enhance the performance of metal bipolar plates. Additionally, significant advancements have been made in the design technology of metal bipolar plates. Non-humidified metal bipolar plates have been developed, utilizing a corrugated flow field structure to effectively distribute fluid on the plate surface. By adjusting the parameters of corrugation cycles, water management within the stack can be achieved without the need for additional humidification. Furthermore, flexible graphite bipolar plates represent another type of bipolar plate with a thickness of less than 1 mm. They have been applied in fuel cell stacks with a current density of up to 2.5 A/cm² and can accumulate fault-free operation for over 20,000 h, making them a competitive new technology. Future trends in bipolar plate manufacturing include innovative flow field design, efficient manufacturing processes, and stringent cost control. For metal bipolar plates, the development of low-cost and highly durable corrosion-resistant coatings is a key breakthrough issue that needs to be addressed.

3.2. Compressor Technology Status

The technology of compressors for fuel cell vehicles mainly focuses on core components such as rotors, bearings, controllers, and high-speed motors. At the same time, the compatibility and adaptability of a compressor with automotive components are crucial, requiring targeted development based on the needs of the vehicle manufacturers. Currently, screw-type compressors with a compression ratio of up to 3.2 are available, and the exhaust flow rate can range from 17 g/s to 400 g/s, allowing for the flow adjustment of fuel cell vehicles under different operating conditions. The development of compressors with large air flow, high energy efficiency, and the ability to respond quickly under all operating conditions will be the future direction of development.

3.3. Onboard Hydrogen Storage System Technology Status

The hydrogen storage system industry chain and manufacturing technology are critical for the large-scale operation of fuel cell vehicles. Regarding hydrogen storage cylinders, the technology for 35 MPa and 70 MPa hydrogen storage cylinders has matured and formed a production capacity that is compatible with vehicle assembly, which is successfully applied in fuel cell vehicles. For example, 70 MPa type IV hydrogen storage cylinders have been widely used in fuel cell passenger vehicles, with a hydrogen storage mass fraction of up to 5.7%. Currently, the development of high-pressure hydrogen storage containers with capacities of 100 MPa is underway. In the future, onboard high-pressure gaseous hydrogen storage technology will be developed to achieve higher pressure, lighter weight, and lower costs.

Hydrogen fuel cell vehicles are pollution-free and achieve zero emissions, making them the new generation of clean vehicles. Academia and industry should vigorously develop hydrogen fuel cell vehicles and propose policy support to quickly break through key technologies, promote demonstration operations, focus on conducting demonstration evaluations, improve the standard regulatory system, and comprehensively enhance testing and evaluation capabilities. It is believed that through diligent research and concerted efforts, researchers will soon improve core technologies, establish sound production and support systems and regulatory frameworks, and achieve the wide-spread and large-scale operation of hydrogen fuel cell vehicles at an early date.

To explore and advance the potential of fuel cell applications in revolutionizing the automotive landscape, a Special Issue entitled “Revolutionizing the Automotive Landscape: Fuel Cell Applications Powering the Future” has been launched. This Special Issue aims to amalgamate cutting-edge research and innovative contributions in the field of fuel cell applications for automotive propulsion. It will provide a platform for researchers, engineers, and industry experts to share their insights, advancements, and perspectives on the latest developments in fuel cell technology and its integration into vehicles. Together, let us shape the future of sustainable transportation.