Gaston Planté

Gaston Planté was a French physicist whose invention of the rechargeable battery, and improvements to (*or invention of) the lead-acid battery, have had an enormous impact on our lives.

Four years prior to this invention, Planté also gained some renown when he discovered the fossils of a prehistoric bird, which was then named after him.

*In history, there is often disagreement about who really invented what. Most sources cite Gaston Planté as the inventor of the lead-acid battery. Other sources cite Wilhelm Josef Sinsteden.

Lead-Acid Batteries

Battery materials

Lead acid batteries consist of three parts: two different forms of the metal lead, and an acidic liquid in which the leads sit without touching each other.

The two kinds of lead are: pure lead and lead oxide.

The acidic liquid is made of up of sulfuric acid (one-third) and water (two-thirds)

Chemical reactions, buildup of electrons

Chemical reactions occur when a strip of each type of lead is submerged in the acid. These chemical reactions cause a buildup of electrons on one of the strips of lead (the pure lead strip). These extra electrons give that strip of lead a negative charge. It also means that the other strip of lead (lead oxide) has a positive charge, simply due to the fact that it has fewer electrons than the other strip. It is positive (has fewer electrons) relative to the other strip.

The electrons will want to move from where they are many (the negative side) to where they are few (the positive side). But because the two strips of lead are not touching each other, the electrons can’t move. They can’t go anywhere because they don’t have a “road”, so to speak, to travel on. This puts the battery in a state of simply storing energy for future use.

Moving electrons, creating electricity

But, if we connect the two strips of lead with a wire, then we have created a kind of highway for them to travel on. The electrons will then flow through the wire from the negative strip of (pure) lead to the positive strip of lead (oxide). This flow of electrons is what we call electricity. If we connect other things (like a light bulb) along the wire between the two lead strips, then we can use that flow of electricity to power our stuff.

Dead battery, recharging

However, the chemicals needed to create the reactions that cause the buildup of electrons will eventually run out. When these chemicals run out, the battery becomes “dead” and can no longer create electricity.

However, the chemical reactions that created the electricity we used can be reversed in lead-acid batteries by supplying the battery with electricity from a different power source.

Rechargeable Batteries vs. Disposable (Primary) batteries

Disposable batteries only work one way, they can only provide electricity to make something run. Electric power can only leave disposable batteries. In contrast, rechargeable batteries can not only provide power, but they can also accept and store it.

Power can only exit disposable batteries

New disposable batteries come with a certain amount of power. As the batteries are used, reactions take place that use up the chemicals that generate the power. When all of the chemicals are gone, the ability to generate power is gone, and the battery is irreversibly dead.

Power can both exit and enter rechargeable batteries

The chemical processes that use up the energy in a battery can be reversed in rechargeable batteries by supplying the rechargeable battery with energy from an outside source. This energy is stored in the battery for future use.

Car Batteries

Lead acid batteries are used in cars and other vehicles because of their ability to supply bursts of very high power to start the car and because they are rechargeable.

When you turn on the ignition in your car, the battery provides a short burst of high power that starts the engine. Then, as you drive, the engine recharges the battery via the alternator.

This recharging of the battery as you drive is why you will be told to drive around for a while after getting a jump start for a dead** battery. The “rechargeable” property of a car battery is also why it can be jump started in the first place. Because it is rechargeable, the “dead” car battery can accept and store energy provided by another power source (another car battery, portable car charger, etc.) It is also why car batteries last for a really long time despite a lot of use.

**A “dead” car battery that can be jump started is not truly dead, in the sense that it can still be revived. Dead lead-acid batteries can be “brought back from the dead” a certain number of times. But if this is done repeatedly, eventually the battery will truly die, cannot be revived anymore by any means, and will no longer work.

Fossil Discovery

In 1855, Planté discovered the fossils of a flightless prehistoric bird near Paris, France. The bird, “Gastornis”, was named after him.