- ChyiLv 41 decade agoFavorite Answer
I did some research work on li-ion battery long time ago. I will try to answer your questions based on what I know and what I can find on the internet. My knowledge may have been outdated.
Li-ion battery - 2nd/3rd generation rechargable battery, so called intercalation/insertion/rock-chair type batteries. This is different from the 1st generation lithium (metal) battery.
Q1 & Q2. What happens if battery is overcharged
Ans: lithium-ion is designed to operate safely within their normal operating voltage but become unstable if charged to higher voltages. When charging above 4.30V, the cell causes plating of metallic lithium on the anode; the cathode material becomes an oxidizing agent, loses stability and releases oxygen. Overcharging causes the cell to heat up. If left unattended, the cell could vent with flame.
Bonus: What are the preventive measures against over-charging:
Ans: Commercial lithium ion packs contain a protection circuits that limit the charge voltage to 4.30V/cell, 0.10 volts higher than the voltage threshold of the charger. Temperature sensing disconnects the charge if the cell temperature approaches 90°C (194°F), and a mechanical pressure switch on many cells permanently interrupt the current path if a safe pressure threshold is exceeded. Exceptions are made on some spinel (manganese) packs containing one or two small cells.
more resources here -
2008-02-26 15:26:09 補充
In normal recharge cycle, li-ions intercalate into layered anode structure (usually its graphite). In an over-change cycle, li-ions plate onto anode and form dendrite metal structures, posing a potential short-circuit or even explosion risk