Leaving aside the "Baghdad Battery" (which likely isn't a battery) the first widely published battery was invented by Volta some time around 1798 to 1803. It wasn't very practical and the next development was the Daniel Cell in 1836. Then a significant development was a "wet" cell by Georges Leclanché 1866 using Zinc and Carbon.
There were then three developers of a "dry" version (stable paste) of the Leclanché Zinc Carbon cell in 1887, one in Japan, but F. L .Wilhelm Hellesen in Denmark was probably first to market in 1887. The brand now belongs to Duracell (founded by Mallory and now owned by Proctor and Gamble) but GP batteries obtained all the other assets in 1992 shipping the last Danish factory contents to Malaysia in 2002. There appears to have been Hellesen production in the UK at one time.
One of the early Entrepreneurs was Conrad Hubert (Akiba Horowitz), a Russian immigrant in New York USA, who founded the "American Electrical Novelty and Manufacturing Company (AENMC)" making batteries and flashlights under the "Ever Ready" brand. Then in 1905, he and W.H. Lawrence, who had manufactured batteries to power home telephones, formed the Ever Ready battery company, later to become Eveready in the USA. All the batteries were the disposable but "sealed" (unlike Telegraph batteries) similar to the Hellesen type. The oldest battery type / size still in use today is probably the "F" cell from 1896. The popular "AA" size dates to pre WWI 1900s, perhaps 1906 and called "Pen Cells" as many British soldiers were issued with Fountain Pen sized Flashlights with two cells.
The designations A, AA, B, C, D, E, F and G etc actually created in the USA in 1947, the batteries all existed many years before. Today the IEC designations are often on batteries and cells. Currently only AA, AAA, AAAA, D, C and N are sold separately but the A cell size is used for NiMH (1.25V) and Lithium (3.4V to 4.2V) cells sealed inside battery packs, though the NiMH is rare. The F size and B size are still made and used inside 6V lantern Packs and "flat" 4.5V Flashlight packs (more common on Mainland Europe than UK, Ireland or USA).
Most original single use cells (up to 1940s) were mostly Zinc Carbon, though Zinc Air and Mercury button cells used in specialist applications before 1940.
Why a Flashlight?
One explination of the name is because of two features of the 1896 to 1905 (approximate) batteries and flashlights. The early bulbs (lamps) used a carbon filament as the Tungsten filament wasn't developed then. These use a higher current for the same brightness. The early batteries were not good purity of ingredients and in use a film of hydrogen would quickly form (polarisation). Hydrogen sets up an opposing voltage and is a poor conductor. This meant the torch would initially flash brightly and quickly dim. Leaving it off for a short while the Hydrogen would react to form water. "Bounces back for extra life" thus wasn't just a marketing slogan.
Later some Zinc Chloride, some mercury on the Zinc and purer Manganese Dioxide coupled with better construction the "polarisation" effect was greatly reduced. The more efficient tungsten filaments also helped. It's no accident that valve (tube) development thus starts just after the availability of batteries and tungsten filaments as those with a 2nd (diode) then third plate (triode) makes a valve work.
Early Applications of batteries
- 1840s : Telegraph
- 1880s : Telephone
- 1890s : Flash lamp, torches, Cycle lamp, Experimental Radio and Hearing aids (before valve / tube use)
- 1900s : Medical devices (Shock, Cautery), Valve (tube) Commercial Radio, Record recording amplifiers.
- 1921 : Domestic Valve/Tube applications: Domestic Radio, Hearing aids, Record and Phonograph amplifiers.