Volta's tongue

The "voltage" (see the lemon battery) is also the cause of the acidic taste of the metal pencil sharpener. Even if your saliva is used as the electrolyte (a wet piece of paper), the voltaic potential as high as 1.1 V can be generated between the aluminium body and the steel blade.

Volta's piles are everywhere - in cars, cell telephones, computers. Depending on to their application, they have to be durable and resistant (in cars), light (in cell phones) or long-lived (in computers). All these properties can be obtained by a proper choice of the electrolyte and electrodes.

The most popular is still the zinc-carbon battery. Unfortunately, if left for a long time, it undergoes corrosion and can spill-out and damage the appliance.

Lithium assures the highest voltage (3 V) and is the lightest. Unfortunately, in rechargeable batteries it sometimes grows in the dendrite form and can explode.

Metal hydrides and nickel are used in many rechargeable batteries. Cadmium- nickel batteries produce only half of the lithium-battery voltage but are cheap and durable.