As societies explore new sources of renewable energy, automotive manufacturers are taking a closer look at the lithium-ion battery.
To ensure that a lithium-ion battery is reliable and operates under a variety of conditions, however, OEMs must inspect the structural composition of the cell’s components: the anode, cathode, electrolyte, and separator.
Designers need to understand how each part degrades, in isolation as well as when they interact during charge and discharge cycles.
But what are the inspection options? How do you know that you have the right anode? How can you inspect the electrolyte? How do you characterize the overall structure of the electrode material?
In a Webinar titled Developing Higher Density Materials for Lithium-Ion Batteries, Tony Williams from the Massachusetts-based biotechnology company Thermo Fisher Scientific discussed the many analytical techniques used in the characterization of battery materials.
See three of his responses to attendee questions.
“What is the selection criteria for picking the right anode?”
Tony Williams, Senior Manager, Market Development, Materials & Structural Analysis Division, Thermo Fisher Scientific: There is no right answer to that other than to make sure that the selected anode material and chemistry works well with the electrolyte and the cathode so as to limit the degradation products that can occur. You want to make sure that the solid electrolyte interface does not get very thick. It’s a layer that can form and will form as you charge and discharge. You just want to make sure that it doesn’t get very dense, because that will degrade the performance of the battery.
“Which techniques are often used to characterize electrolyte performance?”
Tony Williams: There are a variety of techniques that are used to confirm performance. You’ll find that chromatography and mass spectrometry is used to do certain elucidation studies as the battery degrades over time. And you’ll also see corollary studies also done using X-ray photoelectron spectroscopy (XPS) as well as Raman spectroscopy.
“Why would a developer use X-ray diffraction?”
Tony Williams: One would use X-ray diffraction in order to understand and characterize the overall structure of the electrode material, for example. That includes the microstructure as well as the crystalline structure as users are able to gain information about the polymorphic structures, percent crystallinity, phase transition, stability, reactivity, texture, and stress of the sample. Also, if they are doing quantitative phase studies, they are able to make determinations; that can only be done with X-ray diffraction.
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Transcript
00:00:04 In a lithium ion battery such as those used in cellphones and electric vehicles, the electrolyte inside the battery is an organic liquid. This organic liquid is flammable like gasoline. In the event of a crash or a mechanical event that smooshes that battery. The electrodes touch each other and all the energy is released at once. That energy is given off in the form of heat, which causes the organic to heat up, vaporize and eventually it could catch on fire. The SAFIRE technology replaces the electrolyte with a new electrolyte that is a liquid under normal circumstances, but the minute you hit it, it becomes a solid. That solid forms a solid barrier between the materials and prevents them from touching
00:00:44 during a crash. The nice thing about the SAFIRE technology is that it's a drop-in solution, compatible with existing manufacturing processes. You don't have to re-tool production lines or re-imagine how to build the batteries, you can use existing facilities just a slight modification of the electrolyte. Envision putting it in automotive applications.The benefit of an automotive application is that if make your battery tougher, preventing any impact damage to it, you could theoretically remove several hundred pounds of armor around your lithium ion battery. Now your car will go farther on the same size battery, because you're not carrying around as much dead load of armor around the battery.
