lithium-ion (Li-ion) battery

A lithium-ion (Li-ion) battery is a rechargeable battery that stores and releases energy by moving tiny charged particles called lithium ions between two materials inside it.

• When the battery is being used, lithium ions move in one direction and electrons flow through the device’s circuit, providing electrical energy.
• When it is charged, an external electricity supply pushes the lithium ions back in the opposite direction, ready for use again. It works a little like moving marbles back and forth between two boxes.
• Li-ion batteries are popular because they can store a lot of energy for their size and mass. This makes them useful in thin phones, lightweight laptops, wireless earbuds, and electric vehicles.
• They gradually lose capacity because the materials inside change slightly during each charge-and-use cycle. A battery that once lasted all day may therefore need charging more often after a few years.
• Heat matters: high temperatures can damage a Li-ion battery and make it less safe. Devices use protective circuits to control charging and prevent overheating.
• The lithium and other metals inside are valuable, so recycling old Li-ion batteries helps recover useful materials and keeps harmful waste out of soil and water.