Skip to main content

How power became portable: An introduction to battery technology

Several batteries stacked up, side by side.
Borys Shevchuk / 123RF
The modern world, in all its grandeur and complexity, runs off a shockingly primal force, one that has been flowing through human bodies long before the first motor was built. Electricity, that same force that has kept human hearts beating for as long as there have been human hearts to beat, today flows through the veins of civilization, powering the skyscrapers we work in and the phones in our pockets.

Although the great producers of electricity, colossi like the Hoover Dam, may be the most viscerally impressive, human mastery of electrical currents is perhaps most impressive in the form of batteries. Some small enough to sit on the tip of a finger, batteries power many of the devices we use every day: phones, laptops, flashlights, watches. They have been an omnipresent part of life for decades now, but how many of us know how they work?

Beneath their simple exteriors, a simple mechanism

A typical alkaline battery will be familiar to many people, at least from the outside. Generally encased in a metal cylinder, the battery has two ends marked as + (positive) and – (negative). The two ends of a battery are terminals, connected to electrodes within the battery: the positive end connects to a cathode, while the negative end connects to an anode. A separator inside the battery keeps the two from touching, while allowing electricity to flow between them. Between the two ends is an electrolyte paste, a substance that allows for the flow of electrical current.

anatomy of battery

Electrons naturally want to flow from the negative end (where there are excess electrons) to the positive end (where there are open spaces for electrons), however they cannot do so because the separator blocks their path. By connecting the positive and negative ends of the party, a circuit is formed that allows electrical current to flow.

circuit diagram

When a battery is plugged into a device, such as a flashlight or remote, a circuit is established and chemical reactions occur in the anode and cathode. In the anode, an oxidation reaction occurs, where ions combine with the anode and release electrons. In the cathode, a reduction reaction occurs, with ions and electrons forming compounds. In these oxidation-reduction reactions, electrons are flowing from the negatively charged anode to the positively charged cathode.

In an alkaline battery, the anode is made of zinc, while the cathode is manganese dioxide. The electrodes in these batteries erode over time. Rechargeable batteries are usually made of lithium-ion. When plugged in to recharge, the flow of electricity reverses, returning the anode and cathode to their original states.

A brief history of batteries

The earliest object resembling a battery may have been built as early as the 3rd century AD, in the form of clay pots uncovered in 1938 by a German painter, Wilhelm König, near Baghdad. Inside each pot was an iron rod wrapped in a sheet of copper. There was enough room in the jars to contain some sort of electrolyte solution, and so König believed the pots to be galvanic cells, possibly used by inhabitants of the Sasanian Empire for electroplating, the process of using an electric current to produce a metal coating.

Sure enough, experiments aimed at recreating these devices (including one by the popular show MythBusters) have found that the design can produce a small voltage, large enough for electroplating. Despite this, most archaeologists today believe that the pots were not used as batteries in the period they were built, but rather as storage vessels for sacred scrolls. Metallic coatings in the period the jars were built was done through a process of fire-gilding, so König’s electroplating theory seems flimsy. Whatever purpose the Baghdad batteries were designed for, they are at least an interesting curio, inadvertent proto-batteries built long before scientists would come to better understand electrical currents.

The first true battery was built in 1800 by Alessandro Volta. In his days as a professor at the University of Pavia, Volta worked with Luigi Galvani, a biologist who discovered while dissecting a frog that, when his scalpel touched the brass hook holding the frog up, its legs would twitch. Galvani (who would inspire the word “galvanize”) believed that this was evidence of an electrical force that animates life, which he dubbed “animal electricity.” Volta reproduced Galvani’s experiment, but came to a different conclusion: it was the connection between the metal scalpel and hook, not the life force of the frog, that produced an electrical current.

Volta’s research led him to create the voltaic pile, stacking discs of zinc and silver, with cardboard soaked in saltwater between them. Connecting the top and bottom disc with a wire, Volta was able to produce an electrical current, and lay the foundation for future batteries. In honor of Volta’s work, the unit of measurement for electrical potential is known as the volt.

The battery as we know it today is a relatively recent invention. Working for Union Carbide on the Eveready battery line in the 1950s, engineer Lewis Urry was given what seems today like a remarkably mundane task: make longer lasting batteries for toys. Rather than improve on the existing design as his bosses expected, Urry decided to create a new battery, and eventually settles on using a mixture of manganese dioxide and powdered zinc. Thus, Urry created the modern alkaline battery, capable of powering devices for exponentially longer than the previous commercial batteries. Although the first alkaline batteries hit the market in 1959, frequent improvements have kept them viable even to the present day.

Editors' Recommendations

Will Nicol
Former Digital Trends Contributor
Will Nicol is a Senior Writer at Digital Trends. He covers a variety of subjects, particularly emerging technologies, movies…
New battery technology uses miniature fire extinguisher to stop spontaneous combustion

In the wake of the explosive Samsung Galaxy Note 7 scandal, engineers are researching ways to mitigate heat buildup in smartphone batteries. One of the newest approaches, detailed by a team of Stanford University scientists this past week, uses what amounts to an internal fire extinguisher to douse sparks before they turn into flames.

In a paper published in the journal Science Advances, authors describe a polymer shell within the battery that contains triphenyl phosphate (TPP). The flame-retardant compounds sit shielded from the the battery's electrolytes -- the chemical medium that facilitates the flow of electrons between the battery's negative and positive poles -- unless and until the battery reaches a certain temperature threshold.

Read more
Jackery's Power Pro portable generator brings plenty of juice to your campsite
jackery power pro

It used to be that when we set out on a camping trip we left home with just a backpack filled with the essentials, most notably a tent, sleeping bag, and stove to cook our meals. Nowadays, it seems more and more of us are also carrying our favorite gadgets with us into the back country, giving rise to the need to keep those devices charged when we're living off the grid. But Jackery is hoping to make that process a lot easier with the introduction of the Power Pro, a portable generator specifically designed for use in the great outdoors.

The Power Pro launched on Kickstarter a couple of weeks back with a modest goal of raising $50,000 to get the oversized battery pack into production. It didn't take long for supporters to push funding past that level, and now it appears that the device will begin shipping sometime in early 2017.

Read more
Book-sized battery can power a TV for 4 hours or a mini-fridge for 8
plug funded on indiegogo akx3k9sef5pfvy4rsru8

Battery packs are typically either portable, or powerful enough to charge more than a smartphone, but not both. The 35-ounce Plug, however, boasts a capacity sufficient to recharge a DSLR 30 times, a laptop 3 times, or a smartphone 28 times while still being slim enough to slide into a bag. Designed by California-based ChargeTech Enterprises, Plug has surpassed its original Indiegogo campaign goal over 2,000-fold.

After hitting its initial goal, ChargeTech entered production of the Plug on October 12, and extended the campaign by another 30 days. Despite the device’s large capacity, the Plug measures closer to a hardcover book than a high capacity battery at just 1.6 inches deep, 8.6 inches tall, and 5.6 inches wide.

Read more