The desert scene in the 1960s spaghetti western “The Good, the Bad and the Ugly” shows the desperation of Clint Eastwood’s character as Eli Wallach’s Tuco dumps the precious water he craves onto the desert sands. That scene came to mind after reading about the recent research of the University of Saskatchewan’s Canadian Light Source facility and Dalhousie University.
The charging and discharging of lithium-ion cells causes microcracks to form in the cell electrodes and these cracks cause the precious liquid electrolyte to drain away. The electrodes act like Clint Eastwood’s desert sands. Mining.com explained the findings of this research in a recent article titled “How charge, discharge cycles make Li-ion batteries bleed to death”. The articled quoted the lead researcher Toby Bond who explained how batteries will degrade faster when they are packed with more energy.
While we may think of the charge/discharge cycle as a chemical process, at the atomic level it’s much more a physical process. Charging and discharging of lithium-ion cells causes the movement of atoms in the electrode materials. This process leads to tiny cracks in the surface and when the cells have more energy, then the process also accelerates and the outcomes become worse.
The researchers using detailed CT scans could conclude that these cracks propagate over time. It’s this propagation of the microcracks that have the detrimental impact on the cell performance, as the liquid electrolyte gets sucked down into the caverns now formed in the electrodes. As the electrolyte becomes depleted, the crucial medium for conducting the battery cell’s ions fails to perform uniformly. Research such as this one will provide battery cell manufacturers with invaluable insights to improving cells production into the future.
Considering such obvious hazards, cell designers take a multilayered approach to protecting against various potential hazards. Bourns® Mini-breaker Thermal Cut-off (TCO) devices are optimal solutions in the protection architecture that are being increasingly used in lithium-ion battery cell arrangements. TCO devices are designed to provide accurate and repeatable overcurrent and overtemperature protection.