Solid-State Batteries (SSBs) utilize solid-state electrolytes, providing enhanced safety, stability at higher temperatures, higher energy density, compact size, and durability compared to traditional liquid electrolyte-based lithium-ion batteries. SSBs find applications in portable electronic devices and more.
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How thick electrodes affects the electrochemical reactions in Solid-State Batteries (SSBs):
Recently, a research team from Northeastern University in Boston and the U.S. Department of Energy’s Argonne National Laboratory conducted tests to investigate how the composition of thick electrodes affects the electrochemical reactions in Solid-State Batteries (SSBs). The team utilized resources from the Advanced Photon Source (APS), a scientific office facility located at the Department of Energy’s Argonne location.
Experimental Setup:
Researchers likened the battery to a sandwich, with the positive and negative electrodes on either side and the separator and electrolyte in the middle. When the battery provides power, lithium ions flow from the negative electrode to the positive electrode through the electrolyte. SSBs don’t require traditional separators and instead use a solid-state electrolyte to separate the positive and negative electrodes, which necessitates thicker positive electrodes.
In this study, the team evaluated thick positive electrodes composed of two materials, including a sulfide solid electrolyte called LPSC and NMC (nickel, manganese, cobalt) positive electrode active material (CAM). Researchers varied the composition of these two materials, with some batteries containing 80% CAM and 20% LPSC, others containing 70% CAM and 30% LPSC, or 40% CAM and 60% LPSC. Then, X-ray imaging and scattering were used on six slices of the positive electrode and solid-state electrolyte at APS beamline 6-BM-A to measure them.
The researchers segmented the positive electrode into slices, hoping that all the slices would perform the same function. In reality, altering the composition or thickness of the positive electrode can change where the electrochemical reactions take place. The team characterized the electrochemical reactions within the battery. When studying batteries, power at both ends is often measured. However, there is a complex structure in the middle that determines the battery’s performance. By using X-ray beams to penetrate battery materials, researchers can non-destructively study the performance of various parts within the battery.
Results:
The results indicate that the composition of the positive electrode has a significant impact on the electrochemical reaction process. For example, in the SSB with an 80% CAM positive electrode, the positive electrode slice closest to the negative electrode reacts first, and the farthest slice reacts the slowest. However, in the SSB with an 80% CAM positive electrode, the farthest slice reacts first, and the closest slice reacts last. The uneven reaction heights may lead to faster degradation of battery materials.
Conclusion:
To design better batteries, understanding the reactions occurring inside the battery is an important step. These batteries can be used in electric vehicles, portable electronic devices, and other applications. The specific design of solid-state batteries will determine their application areas and the direction for future optimization.
