Professor Hanington’s Science Talk: New and Improved Lithium-Ion Batteries Coming (Part 1) | Lifestyles

GARY HANINGTON

Have you seen the new power tools lately? They all display their nominal voltage in large letters. 60 volts! 50 volts! Next year there will be 100 volt batteries.

One thing is certain, all portable drills, sanders, saws, even leaf blowers these days use lithium-ion batteries. I just purchased a battery operated sidewalk edger. The last one was destroyed when the person using it ran over the electrical cord in their haste to finish the job as fast as they could. The new one takes a lithium-ion battery. I wonder what they’ll break next.

Because all of these new battery-powered power tools use lithium, we should take a look at the science of lithium batteries starting with the element and ending with new improvements fresh out of Argonne National Laboratory. .

Metallic lithium was discovered in 1817 by Swedish scientist Johan Arfwedson who was working on projects in the laboratory of chemist Jöns Berzelius in Stockholm. He detected the presence of a new element during the analysis of petalite ore (LiAlSi4O10) and found that the new element formed compounds similar to those of sodium and potassium, although its carbonate and hydroxide were less water soluble and less alkaline. Its patron, Berzelius, gave the alkaline material the name “lithiona”, from the Greek word meaning “stone”. They then isolated the shiny metal using molten oxide electrolysis.

People also read…

Lithium is a relatively rare element, making up about 0.002% of the earth’s crust. It is usually found in pegmatite formations as spodumene and lepidolite. Besides Chile, one of the largest lithium reserves is in the Salar de Uyuni region of Bolivia with 9.2 million tonnes of ore.

A few years ago, the US Department of Defense deemed Afghanistan’s lithium reserves to be as large as Bolivia’s and dubbed it a potential “lithium Saudi Arabia.” Fortunately we are no longer there and probably better for China which has now concluded an agreement for this region.

In our CHEM122 class at Great Basin College, we often made “batteries of beakers” using various elements and their compounds separated by an aqueous salt bridge. Students learned to predict the voltage the battery would produce by looking at the standard electrode potential chart. They were able to calculate that a copper-zinc Daniels cell could generate 1.1 volts and a silver-zinc André cell would give 1.6 volts. Near the top of the list however was lithium and it could make a 3 volt battery!

As everyone knows, the higher the voltage, the more power you can easily get. That’s why car manufacturers switched from 6-volt batteries to 12-volt batteries in the 1960s. Unfortunately, we could never make a lithium battery in the classroom because, like sodium, metallic lithium is also reactive and just plain too eager to give up its electrons. Aqueous electrolytes and lithium cannot be mixed. There is another reason: at more than 1.5 V, water is split into hydrogen and oxygen – a safety problem that has already appeared in lead-acid batteries. If the lithium battery were to produce nearly double that voltage, the chemists had to find a different electrolyte to put the electrodes on. It took many painful years before someone found a way to shape lithium metal into a battery.

In the late 1950s, University of California, Berkeley doctoral student William Harris identified propylene carbonate, a C4H6O3 organic liquid, as the most promising candidate for making a lithium battery. Because it could conduct electricity but contained no water, metallic lithium simply acted as an electrode – it did not produce bubbles of hydrogen gas. These studies suddenly increased the commercial interest in rechargeable lithium-ion batteries.

Since the late 1970s, non-aqueous 3V lithium-ion rechargeable batteries have been commercially available in a variety of products. A lithium manganese oxide was used by Sanyo in their CS rechargeable solar calculators and you may remember the Exxon lithium TiS cell for electric cars that came out during the second gasoline shortage in 1979. They dropped the product after dangerous fires and toxic hydrogen sulfide. emissions were attributed to the new product when it was still in its infancy.

The 2.8-volt lithium-iodine battery deserves a mention. Used since 1972 to power pacemakers, the battery has a lifespan of ten years and must be reliable. It is constructed by adding molten lithium alloy directly to the quarter-sized mass of iodine, forming an anode and separator at the same time and is completely solid.

But, as you can see in the past 30 years, there has been very little movement with lithium-ion cells. To illustrate this, I still have a blue-green Makita hand drill in my store that I purchased in 2003. It used a nickel-cadmium cell block that is now dead. But I’m keeping it on the top shelf because this baby has punched a lot of holes in her day. Sort of grazing now.

So what has caused the explosion of new lithium devices over the past five years?

Intercalation. We’ll cover that next week.

Gary Hanington is Professor Emeritus of Physical Sciences at Great Basin College and Vice President of Engineering at AHV. He can be contacted at [email protected] or [email protected]

Comments are closed.