A mix of industrial waste, some plastic, and a moderate temperature could be the key to unlocking the next big breakthrough in battery technology. Researchers from the National Institute of Standards and Technology (NIST), the University of Arizona, and Seoul National University in South Korea have developed a low-cost, high-performance lithium-sulfur battery. According to the team, the new battery can match the performance of today's mainstream lithium-ion batteries and maintains its efficiency after 500 charge-discharge cycles without significant degradation.
Over the past few decades, lithium-ion batteries have seen steady improvements in energy density, making them the go-to choice for smartphones and other portable electronics. However, these batteries rely on heavy cathodes made of materials like cobalt oxide, which limits how much more energy they can store. This drawback makes them less ideal for applications that demand higher energy density, such as long-range electric vehicles.
In response, scientists have turned their focus to lithium-sulfur batteries, a lighter and more promising alternative. Sulfur, a byproduct of the oil industry, is not only cheaper but also has a lower weight compared to cobalt. Because sulfur can hold twice as many lithium ions per unit volume as cobalt oxide, lithium-sulfur batteries offer significantly higher energy density—making them a strong contender for future energy storage solutions.
Despite this advantage, sulfur-based cathodes come with two major challenges. First, sulfur tends to react with lithium, forming crystalline compounds that reduce battery performance. Second, repeated charging and discharging can cause the sulfur cathode to crack, leading to rapid failure. As a result, most lithium-sulfur batteries typically last only a few cycles before becoming ineffective.
To address these issues, researchers at NIST and their collaborators used a novel approach called "reverse vulcanization." They heated sulfur to 185°C, creating chains of eight sulfur atoms, and then combined them with diisobutylene (DIB), a carbon-based polymer precursor. This process linked the sulfur chains together, forming a stable composite material. Unlike traditional tire vulcanization, where carbon binds sulfur, this method uses sulfur as the main component, with DIB acting as a stabilizing agent.
The researchers found that adding between 10% and 20% DIB by mass provided the best balance. Too little DIB left the cathode vulnerable to cracking, while too much reduced the battery’s overall energy capacity due to DIB’s inert nature. The resulting material prevented both structural damage and unwanted crystallization, significantly improving the battery’s durability.
Testing showed that after 500 cycles, the battery retained over half of its original energy capacity. Jeffrey Penn, a chemist at the University of Arizona, noted that while other experimental lithium-sulfur batteries have shown similar performance, their production methods are expensive and not yet scalable for mass manufacturing.
Christopher Sowers, a materials scientist at NIST, emphasized that while the new battery represents a major step forward, it won’t hit the market anytime soon. Sulfur is highly reactive and flammable, so any commercial lithium-sulfur battery must pass rigorous safety tests before being considered viable for consumer use. (Liu Xia)
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