Rechargeable Lithium

[pdj]

Hello everybody. I hope you can help with

Why do rechargeable batteries use lithium instead of other metals?

Thanks

Pete

[NanoMachine]

One very good reason is lithium's very low density. You can store a lot more electrical energy in a kilogram of lithium than in a kilogram of iron or other metals.

[pdj]

Thanks Nanomachine. Density is very low.

[thor3436]

have you ever
lit lithium on fire
it burns so brightly its like looking at the sun!

[whitfield]

Originally Posted by NanoMachine

One very good reason is lithium's very low density. You can store a lot more electrical energy in a kilogram of lithium than in a kilogram of iron or other metals.

Rechargeable lithium batteries (secondary batteries) don't contain lithium metal, they contain lithium salts.

Its only primary lithium batteries (throw away after they're discharged) that contain the metal.

[NanoMachine]

Sorry, I need to engage brain before hitting keyboard.

Not all rechargeable batteries use lithium, but the ones with the highest energy densities do.

An alkaline battery will give you about 0.3 MJ of energy per kg of battery and a Li ion battery will give you about double that.

The higher energy density doesn't come because a Lithium battery is lighter than alkaline or Nicad batteries, it comes because lithium batteries produce about double the voltage.

[whitfield]

Lithium-ion batteries have no memory effect.

You know how NiCd rechargeables lose performance if you don't either fully charge them or fully run them down before recharging? This is called the memory effect. The batteries "remember" you didn't fully charge or discharge them. They will only charge up or run down to whatever charge they had when you didn't fully charge or discharge them. You can never get the amount of energy from the battery again that ought to be available.

You don't have this problem with lithium-ion batteries. If you don't fully charge or discharge them they won't lose performance. Anytime you like, you'll be able to fully charge them again. (You also don't have the meomory effect with NiMH - nickel metal hydride - rechargeable batteries.)