X-ray CT and the developments of fuel-cell technology

The automotive industry is facing huge challenges especially with the development of NEVs, New Energy Vehicles. In public transportation and distribution, battery-electric vehicles are currently the focus of attention, but electromobility is already facing limitations in some areas. Apart from the rapid development of battery technology, H2 is a complementary technology as an alternative fuel for long-distance transport. Hydrogen as an energy carrier and hydrogen fuel cell are considered key technologies for the electromobility of the future.

These new technologies are completely different from combustion engine vehicles and require entirely rethinking the manufacturing chain, from manufacturers to suppliers.

RX Solutions innovative X-ray CT technology helps to face this transition by offering a range of innovative quality assurance solutions that assure the reliability, efficiency and safety of e-vehicles.

What is a fuel cell?

A Fuel cell generates electricity through an electrochemical reaction, not a combustion. It works like batteries producing electricity and heat as long as fuel is supplied. A fuel cell consists of two electrodes - a negative electrode (or anode) and a positive electrode (or cathode) - sandwiched around an electrolyte. H2 and air are combined to provide electricity to the electric motor.

The fuel cell stack is the most important component. A single fuel cell generates a small amount of power, which is why engineers stack them in layers by bipolar plates. In a passenger car, a complete stack can go up to 400 fuel cells together. For higher power requirements, the number of stacks can be increased accordingly.

However, manufacturing a system as complex as a fuel-cell stack on a massive scale is not an easy task. Each fuel cell stack needs to be perfectly efficient.

A solution for CO2-free mobility

Hydrogen or H2 is currently a trendy topic as European Union and most developed countries around the world agreed to a zero-emission planet by 2050. From 2024 to 2030, hydrogen must become a key part of an integrated solution to drive energy transition. From 2030 onwards and towards 2050, renewable hydrogen technologies should reach maturity and be deployed at a large scale to decarbonize sectors where other alternatives cannot be used. Hydrogen is propelling European global carbon neutrality, being an efficient technology for zero-emission mobility.

It is needed to achieve a 90% reduction in transport-related greenhouse gas emissions by 2050. Hydrogen fuel cells and battery electric will offer consumers the « power of choice ». Both propulsion methods will cater to varying consumer needs.

Several methods to produce H2

Hydrogen can be produced using several methods: thermal, electrolytic, solar-driven or biological processes. Once hydrogen is produced, storage is quite complex, because of its very low energy density. In addition, hydrogen’s main risk is its ready flammability, a frequently invisible and high-temperature flame to burn of form explosive mixture with air. This risk needs to be reduced at a minimum level for public usage. X-ray CT can play an important role in assuring that the storage tank used in cars are safe and reliable enough to be released on the market.

As a non-destructive technology covering from nano to micro-scale applications, X-ray CT can be used at each step of e-mobility fuel cell production process, from, R&D application to large manufactured parts’ inspection.

X-ray Nano-CT: The best way to get a 3D rendering of H2 electrodes

Nano-CT is very useful for imaging at very high resolution the 3D microstructure of the anode-electrolyte stack. The stack of proton-exchange membrane fuel cell (PEMFC), also known as polymer electrolyte membrane (PEM) fuels cells, where the electrochemical exchange of the reactant gases hydrogen and oxygen produces electricity. The µCT allows to observe defects inside the volume of these stacks and shows their evolution after the electrochemical reaction. A better understanding leads the way to better anticipation of defects.

X-ray nano-CT is a powerful method to get a 3D rendering at a very high resolution of the internal electrode microstructure. This concept is based on the further development of existing micro-CT technology. Parts' structures at a cellular level become obvious when the spatial resolution improves.

The term nano is used to highlight that the pixel sizes of the cross-sections are in the nanometer range, hence this new method is definitely called Nano-CT. Nano-CT is of interest to scan at very high-resolution the 3D microstructure of anode-electrolyte in an electrochemical cell, as well as the reduction behavior. X-ray CT helps to understand and correct the manufacturing process and get the best returns with such cells.

Composite tube

X-ray scan of composite fibers

Micro-CT inspection of a component or assembly

On another scale, X-ray CT can be of interest to image in a non-destructive way the tanks that will be filled of H2. Hydrogen tanks are designed to store hydrogen at very high pressures thus they are many safety concerns. X-ray micro-CT helps to control and inspect accurately the overall tank in a non-destructive way, the external as well as the internal structures. The composite can be fully inspected to look for porosities and delaminations that could weaken the tank.

Compressed hydrogen fuel tanks are made of carbon fiber composites or carbon fiber and metal alloys coupled with composites. The inner line of the tank is a high-molecular-weight polymer that serves as a hydrogen gas permeation barrier.

X-ray computed tomography is very useful to understand the microstructure of composite materials as well as control and inspect the final assembly, looking for eventual defects in the final assembly. The X-ray technology is powerful enough to look into the material and detect delaminations or leaks in a non-destructive way. Hydrogen gas is very dangerous when entering in contact with oxygen, thus the tank needs to be totally sealed without propagating any leakage.

Inline inspection during the manufacturing process

Manufacturing a system as complex as a fuel-cell stack on a massive scale is not an easy task. Each fuel cell stack needs to be perfectly efficient. Fuel cell electric vehicles production lines can be automatically monitored thanks to X-ray CT, thus the defects or drifts can directly be detected.

X-ray CT provides essential flexibility, and with recent technical advancements, a very high components throughput is now achievable. Thanks to the quick feedback on part’s external and internal characteristics, the manufacturing process becomes simultaneously more efficient.

NEVs production monitoring thanks to X-ray CT

New electricity vehicles have fewer components than combustion vehicles but requires a holistic quality inspection. X-ray CT, as an innovative non-destructive technology, can be implemented at each R&D or manufacturing step.

Benefits of inspecting FCEVs components with X-ray CT

- From a single component to a complete assembly

- A technology that can be used at each step of your product life cycle

- A more efficient look inside: holistic inspection of hydrogen components, for the internal as well as external structures

- Only one scan for a wide range of analyses of all sorts

- Easy automation of repetitive tasks including easy replication of analyses across periodic object structures

- Inspection costs and times drastically reduced

With more and more components having complex multi-material structures, finding out whether a part is reliable and achieves conformity restrictions is difficult with traditional testing methods. That is why for aerospace components, X-ray CT offers new inspection alternatives as an all-in-one non-destructive technique representing a 3D model with greater image quality – all while being fast, accurate and automatic.

Discover our CT portfolio, with advanced CT systems and software adapted to your needs.

Our innovative X-ray CT solutions are suitable for product development, turning ideas into reality from brainstorming to the actual product ready for manufacturing. User-driven improvements are the core of our business, offering you optimal solutions with the right and powerful interface & components.

For a better understanding of X-ray CT, check our blog or contact an expert at www.rx-solutions.com