Overcharging occurs when a Lithium-ion Batteries is charged beyond its specified voltage limit, posing a significant risk to its safety and lifespan. While modern electric vehicles incorporate sophisticated battery management systems (BMS) to prevent overcharging, malfunctions can still occur.
When a BMS fails to accurately monitor battery voltage or cut off charging, when necessary, the battery continues to accumulate charge beyond its safe limits. These overcharging triggers a cascade of detrimental reactions within the battery.
At the heart of the issue lies the chemistry of lithium-ion batteries. Overcharging leads to the formation of metallic lithium on the negative electrode, a condition known as lithium plating. Simultaneously, the electrolyte begins to decompose, releasing gases and generating heat. As the battery temperature rises, these processes accelerate in a dangerous feedback loop.
The escalating heat causes further electrolyte breakdown and increased lithium plating, ultimately leading to internal short circuits. This rapid release of energy manifests as thermal runaway, where the battery temperature skyrockets, causing the battery to swell, rupture, and potentially ignite.
Preventing overcharging is crucial for ensuring the safety and longevity of lithium-ion batteries. Robust BMS systems, coupled with redundant safety mechanisms, are essential to mitigate the risks associated with this hazardous condition.