Lithium-ion 'Cell Deformation' during charging & discharging can lead to reduced efficiency and power output, potentially causing uneven ion distribution and decreased capacity. Safety risks are heightened due to the increased likelihood of short circuits, which can cause overheating or even thermal runaway. The lifespan of the battery is also compromised, as deformation accelerates material degradation, shortening the battery's usable life. Additionally, charging cycles become less efficient, and the accuracy of the BMS in monitoring the battery's state can be affected. Overall, cell deformation is a crucial issue that can adversely affect the functionality and reliability of lithium-ion batteries.
Over time, lithium-ion cells undergo physical changes that can lead to several performance issues and operational failures. The need to accurately assess the condition of these batteries is not just about efficiency; it is about safety and sustainability. The study conducted by Kocsis S. et. al. is a response to this need. It utilizes the Digital Image Correlation (DIC) technique, a method that allows for the precise and detailed analysis of battery cell deformation across various states of charge. This technique represents a significant advancement in battery diagnostics, providing insights that were previously unattainable with traditional methods.
The deformation analysis conducted on cylindrical (18650), prismatic, & pouch cells shows crucial information about how these cells behave under different charging and discharging conditions. Using DIC, it was possible to observe and measure the minute changes in the geometry of the cells, correlating these changes with the state of charge (SoC) and state of health (SoH) of the batteries.
One of the interesting aspects of this is how it links the physical changes in the battery cells to their chemical and mechanical processes. These deformations were not just a result of mechanical stresses but also involved complex chemical interactions within the cells. For example, the reaction of electrodes with electrolytes and the development of inhomogeneous particle distribution during lithium diffusion are identified as key factors influencing cell deformation.
The implications of this research are extensive. Accurately diagnosing battery health and predicting failures before they occur can lead to safer, more reliable, and longer-lasting battery systems. It also has significant implications for the recycling and reusability of li-ion batteries, contributing to the sustainability of this critical technology.
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