1991

Lithium Ion Battery

Everyone would like to have better batteries. Wouldn’t it be great to have a smart phone that you recharge once a month, and the recharging time is less than a minute? Wouldn’t it be great to have an electric car that can go 1,000 miles (1,600 km) on a charge and then takes only a few minutes to recharge? Wouldn’t it be great to have a battery the size of a loaf of bread that could run an entire house for a day or two in case of a power failure? What about an electric jet airplane that can fly around the world on a single charge? It is easy to imagine batteries like this, but will we ever see them?

When we think of a battery, what we usually have in mind is a container full of chemicals. Chemical reactions inside the container produce electrons. In a disposable battery, the reaction happens once. In a rechargeable battery, the reaction is reversible.

Scientists and engineers have tried many different chemistries to create batteries: The first widely successful chemistry appeared in the crow’s foot or gravity battery. It used copper and zinc electrodes and copper sulfate crystals in water. This battery powered the early telegraph network starting in the 1860s. Around the same time the rechargeable lead-acid battery first appeared. We still use this chemistry in just about every car battery today. Then came nickel-cadmium, nickel-metal hydride, and lithium ion chemistries. Lithium ion is the best battery technology available today in terms of energy density.

But the lithium ion battery of today, first commercially produced by Sony and Asahi Kasei in 1991, is only three times better than the lead acid battery in terms of its power-to-weight ratio and its power-to-size ratio. When you consider that scientists and engineers have been working for over a century on the problem, very little improvement has been seen compared to other technologies. If you compare a 747 to the Wright Brothers’ airplane, or ENIAC to the computer inside a smart phone, you see that the rate of improvement in other engineering endeavors has been much more fruitful.

SEE ALSO Telegraph System (1837), The Wright Brothers’ Airplane (1903), ENIAC—The First Digital Computer (1946), Boeing 747 Jumbo Jet (1968), Prius Hybrid Car (1997), Smart Phone (2007).

Batteries loaded in a row on an electric car.