In this interview, AZoSensors talks to Gerard White from Teledyne DALSA about lithium-ion battery inspection, he touches upon the difficulties, necessity, and future of these batteries.
What are lithium-ion batteries?
Lithium-ion batteries were developed in the 1980s, and it was in the 1990s when they were first used in smartphones, tablets, and power tools. Their use has been expanding ever since, with demand continuing to grow rapidly worldwide.
What are some of the growing applications of lithium-ion batteries?
Lithium-ion batteries were first commercially developed for portable electronics and are now ubiquitous in daily life in increasingly diverse applications, including electric cars, power tools, medical devices, smart watches, drones, satellites, and utility-scale storage.
What advantages does this technology provide over other rechargeable batteries, especially regarding electric vehicles?
Lithium-ion batteries offer high energy densities and voltage, stability, low weight, long life cycle, and diversity of chemistries, making them a groundbreaking technology that is so far ahead of previous rechargeable battery technologies. Electric vehicles (EVs) are transforming the automotive and transportation industry and are expected to account for between 12 million and 15 million in sales in 2025. This is a tenfold increase in global lithium-ion battery capacity from 2018.
How could lithium-ion batteries help solve the global environmental crisis?
For us, the future will be in driving the global transport and energy systems to electric power and enabling a more decarbonized future.
What challenges are associated with lithium-ion batteries?
Lithium-ion batteries are complicated to make, especially for EV applications where safety, durability, and modularity compete with competitive pressures on performance, efficiency and price. Individual cells must be produced and then assembled into battery modules containing hundreds of cells. Like in any manufacturing process, perfection is the goal, not a destination.
What are the risks of cell failure?
A single-cell failure can require the disassembly of an entire module and the removal of the failed cell or cells. Undiscovered failed cells can cause even greater issues: they can greatly degrade the output power and performance of the whole module and present hazards.
What are some of the methods used to overcome these challenges?
The National Highway Traffic Safety Administration has opened a new investigation into electric and hybrid vehicle batteries after five automakers issued recalls due to possible defects that could cause fires or stalling. The National Highway Traffic Safety Administration said the new probe covers more than 138,000 vehicles with batteries made by LG Energy Solution of South Korea and affects cars made by General Motors, Mercedes-Benz, Hyundai, Stellantis and Volkswagen.
How can inspection lead to safer lithium-ion batteries?
The failure of a battery system in almost any electric system poses multiple hazards. This presents a strong case for increasing quality control testing on all individual cells before and after they are assembled into modules. While each cell and module likely have their current tested at different stages, this only provides a partial understanding.
What are the best inspection strategies?
The best strategy would be to start inspection as early in the production process as possible so as not to waste time and resources on scrapping or recycling a nearly finished product.
Why is initiating these strategies early in the manufacturing process important?
Early defect detection allows manufacturers to finetune the feedback loop, adjusting process machinery to optimize results.
What characteristics of foils can lead to problems regarding the function and safety of the cells?
The quality and consistency of the foils and their coatings are critical to the function and safety of the cells: foreign particles, bumps and non-uniformities can, over time, press or rub through the separator foil, thus causing a short circuit resulting in catastrophic battery failure.
What techniques are used in the inspection of lithium-ion batteries?
The first visual inspection happens in the manufacture of foils, which are used to make the electrodes (cathodes and anodes). Typically, this inspection is done after the slicing or punching processes which can cause particles to be deposited on the surface prior to the rolling, folding, or stacking of the electrodes.
Often, it is a matter of a few dark grey defects on a dark grey background that can determine the performance and lifetime of a battery cell. Manufacturers are finding it important to look for these defects from the 50-micron level all the way down to 10 microns.
What elements determine when these methods will be used in the manufacturing process?
Contact imaging is often used for a ‘rough’ initial pass, but for detailed inspection further down the line, companies are turning to line scan cameras and high-sensitivity TDI (Time Delay & Integration) cameras to provide the necessary resolution and sensitivity.
More innovative solutions have included Multi-Field TDI cameras that provide the additional benefit of simultaneously capturing light from three different spectra and angles, providing more image data for defect detection and analysis without incurring further costs or slowing the system.
Other types of imaging are used at different stages of assembly. High-speed 3D laser profilers are used to measure the form of more 3-dimensional objects, such as the contact tab welding uniformity, tab deformity and orientation. A poorly welded contact tab can break or cause an intermittent loss of contact. Area-scan cameras are used primarily in the packaging of individual cells into larger batteries, where the orientation of hundreds of cells in the housing must be precisely controlled.
What is ‘destructive testing,’ and what role does the Teledyne FLIR high-speed thermal camera play in it?
Destructive or abusive testing consists of exposing batteries to some worst-case scenarios to understand any resulting safety issues. One of the abusive tests that batteries are subjected to is nail penetration, which simulates short-circuiting and may cause the battery to overheat and catch fire or even explode.
Teledyne FLIR’s high-speed thermal camera reveals heat details that other technology cannot capture. With thermal imaging, engineers can easily see not only what is going on outside the battery when it is exposed to an abusive test but also what is happening inside and how the heat is progressing.
What are some alternative investigation techniques for non-destructive testing?
Researchers have also looked at different types of X-Ray diffraction for in situ analysis, including X-Ray and even ultrasound imaging. As with any application, there is a balance between image quality and time.
Some of this can be done with fast 2D X-Ray systems, but visible information is limited. With 3D X-Ray imaging, it is possible to get a full picture for critical aspects of a battery cell and module, while time-lapse (4D) tomography helps to reveal the processes and transformations in an operational battery as it ages.
Industrial computed tomography (CT) is finding more uses in detecting defects and internal changes throughout a battery’s lifecycle. Still, it can be difficult to make out the interesting structures: with the materials being very similar in density and often quite thin, the result is often a low-contrast grayscale image.
CT-data analysis and visualization software are adding functions that allow a more informed overview with the help of artificial intelligence.
Dynamic Neutron Radiography has proven to be another promising option for non-destructive testing, giving researchers real-time data on the inner workings of a system. In comparison to X-Rays, neutron interactions offer some useful advantages to X-Ray imaging, as they interact differently with elements.
About the interviewee
Gerard White is a Senior Business Development Manager at Teledyne DALSA with over 25 years of experience focused on the global sales, support and marketing of industrial imaging cameras.
This information has been sourced, reviewed and adapted from materials provided by Teledyne DALSA.
For more information on this source, please visit Teledyne DALSA.
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