Technology
How does a lithium-ion battery work?
A lithium-ion battery works by shuttling lithium ions between two electrodes through a liquid electrolyte. Discharging sends ions one way and pushes electrons through your device; charging forces them back, storing energy for next time.
See it in motion.
Watch a 2-minute animated lesson that shows exactly how a lithium-ion battery works.
Step by step
- 1It has two electrodes — a graphite anode and a metal-oxide cathode — separated by an electrolyte.
- 2Discharging: lithium ions move to the cathode while electrons flow out through the circuit, powering the device.
- 3Charging: an external supply pushes the ions and electrons back to the anode.
- 4It's rechargeable for hundreds to thousands of cycles before capacity fades.
- 5High energy density makes it ideal for phones, laptops, and electric cars.
Frequently asked questions
- Why do lithium-ion batteries degrade over time?
- Repeated charging slowly forms unwanted deposits and side reactions that trap lithium and shrink usable capacity.
- Why can lithium batteries catch fire?
- Damage, defects, or overheating can cause an internal short and 'thermal runaway,' where heat triggers more heat — good design and protection circuits prevent this.
- Should you fully drain a lithium-ion battery?
- No. Unlike older batteries, they last longer with frequent partial charges and dislike being run to empty.