In its metallic form, lithium is silvery and the lightest of all metals. Most people will remember it from school chemistry lessons when it violently whizzes around on the surface after being dropped into water. The reaction is so vigorous that the metal becomes red hot.
One of the big problems with the metal is that it is highly corrosive and can catch fire spontaneously - in the science lab it has to be stored under oil to prevent its violent oxidisation.
The first commercial lithium-ion battery was released by Sony in 1991, a massive development that revolutionised consumer electronics.
Lithium-ion batteries are filled with a pressurised lithium salt dissolved in an organic solvent, usually ether, with two electrodes and a separator made of non-conductive micro-perforated plastic sandwiched between them. When part of a circuit, lithium ions move from the negative electrode made from carbon (the anode) to a positive electrode (the cathode) made from lithium cobalt oxide, freeing electrons which then travel round the circuit, so creating power.
The batteries are re-charged by applying power to the battery. This forces the ions to move back to the negative electrode and so the process can start over again.
Lithium batteries are light, and have a low self-discharge rate at about five per cent a month. They are far more powerful than comparable batteries using other chemical mixes.
They are available in many shapes and sizes. The battery packs used in electric cars will contain several batteries strapped together to create one unit.
Lithium-ion batteries have a long shelf life, but eventually they stop holding their charge. They are extremely toxic and need to be recycled.
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