It turns out that iodine is an important ingredient. While electron exchange with sulfur is relatively slow, iodine undergoes an extremely rapid electron exchange (technically called a redox reaction). Therefore, it acts as an intermediate in the transfer of electrons to sulfur, accelerating the reaction that occurs at the electrode. Additionally, there is some evidence that iodine has relatively low melting and boiling points, allowing it to move through electrolytes and act as an electron shuttle, the researchers suggest.
Success and cautions
The result is a much better electrolyte that allows for faster charging. Fast charging typically reduces the total capacity that can be stored in the battery. However, when charged at a very fast rate (50C, or a full charge in just over 1 minute), a battery based on this system charges 25 times more slowly (2C, or a full charge that takes 30 minutes). (meaning) had only half the capacity. fully charged).
But what was surprising was the durability of the resulting battery. Even at an intermediate charging rate (5C), it maintained more than 80% of its initial capacity after more than 25,000 charge-discharge cycles. In contrast, lithium-ion batteries tend to reach that level of degradation after about 1,000 cycles. It’s no exaggeration to say that if such performance were possible in mass-produced batteries, it could fundamentally change our relationship with many battery-powered devices.
What is not at all clear, however, is whether this takes full advantage of one of the original promises of lithium-sulfur batteries: more charge for a given weight and volume. The researcher specifies the battery that will be used for the test. One electrode is an indium/lithium metal foil and the other electrode is a mixture of carbon, sulfur, and glass electrolyte. A layer of electrolyte lies between them. However, when giving storage capacity per weight figures, only the weight of sulfur is mentioned.
Still, even if weight doesn’t prevent you from stuffing it into your car or cell phone, there are plenty of storage uses that would benefit from something that won’t wear out after 65 years of daily cycling.
Nature, 2025. DOI: 10.1038/s41586-024-08298-9 (About DOI).
