How is chemical energy stored in cells

Energy storage

Thermal energy can be stored by means of chemical reactions. However, the layperson is much more familiar with the storage of electrical energy via chemical reactions, such as takes place in car batteries. While a galvanic cell or a battery (this is the series connection of several galvanic cells) can convert their chemical energy into electrical energy only once and then have to be disposed of, accumulators are rechargeable. At the moment the most widespread are the lead accumulators, in which two lead plates are immersed in dilute sulfuric acid. A disadvantage of lead-acid batteries is their high weight and thus their relatively low energy density in relation to the mass. For special applications (e.g. battery for laptop or MP3 player), batteries with different electrodes and electrolytes have been developed, which are characterized by a higher energy density in terms of mass or volume. If you are interested in the structure of these newer batteries, you can read the Varta company (address: http://static.varta-consumer.de/uploads/grs_welt_der_batterien.pdf).

The following figure shows the energy density of various accumulators in terms of weight and volume. You can see that the reasonably priced lead battery does not do well for more demanding applications such as electric cars.