Lithium-ion batteries represent a significant advance in battery technology and have enabled many of today’s applications in the first place. Therefore, three of the developers later received the Nobel Prize. In the meantime, however, the technology has become a bit of a victim of its own success. The number of rechargeable batteries has exploded in recent years. This also created strong demand for the necessary raw materials such as lithium – and rising prices. This is likely to increase further in the coming years. Because in addition to batteries for other electric cars, energy storage devices are also urgently needed. The background: the more wind and solar energy that is generated, the more fluctuating production. Ideally, storage options still ensure a stable electricity grid. Researchers at MIT in the United States have therefore now looked around for a cheaper alternative to lithium-ion batteries – and seem to have found real gold.
Aluminum and sulfur serve as new electrode materials
Initially, their approach was very simple: they took the periodic table of the elements and looked for a cheap lithium substitute that was available in large quantities. At first they thought of iron. However, the metal did not have the desired electrochemical properties. Instead, they chose the most common metal on Earth: aluminum. This found one of two electrode materials needed. The researchers then chose sulfur as a counterpart. The advantage: the non-metal is available in large quantities and therefore cheap. The trick was to find the right electrolyte to connect the two electrodes together and get a powerful battery. Here the researchers first experimented with special polymers. However, this approach proved unsuccessful. In the end, therefore, they opted for special molten salts.
The formation of unwanted dendrites is prevented
The newly designed battery performed extremely well in the initial tests, withstanding hundreds of cycles at extremely high charging rates. Surprisingly, no so-called dendrites were formed. These small pieces of metal usually accumulate on the electrodes and eventually cover them. This reduces performance and can lead to a short circuit. The MIT researchers had no intention of solving this problem in any way. But they could have succeeded as a by-product, so to speak. The major advantage of the new battery is its low cost. These are between one sixth and one-tenth lower than conventional lithium-ion batteries. The researchers’ construction is currently sized to serve as electricity storage in single-family homes or small businesses. Further adjustments could also make the development interesting for electric cars. However, this requires official approval.