Researchers have developed a new component that can cure the "Achilles heel" of lithium-sulfur batteries.
Compared with the traditional lithium-ion batteries, lithium-sulfur batteries have an important advantage: the material cheaper, lighter quality. The same quality of lithium-sulfur batteries, energy is equivalent to twice the lithium-ion battery, the energy density in the field of portable electronic devices and electric cars is very crucial.
Increasing energy density is important in both transportation and energy manufacturing to reduce energy storage costs and reduce greenhouse gas emissions. However, after several charge-discharge cycles, the lithium-sulfur battery gradually becomes unstable and the two electrodes malfunction, making it difficult to get onto the "throne" of energy storage. In particular, lithium ions chemically react with sulfur to form compounds that migrate and reduce the battery's storage capacity.
"When that happens, they form a barrier on the surface that prevents lithium from reaching the cathode," said Victor Batista, a professor of chemistry at Yale University in the United States.
In an article in the Proceedings of the National Academy of Sciences on March 20, the United States, Batista and his collaborators showed a composite film that dramatically increases the lifetime of lithium-sulfur batteries.
Researchers first simulated which materials and structures allow lithium-sulfur batteries to last longer and calculate how molecules in the cathode react with different materials. The team then made thin films using graphene (single atom density carbon structure) and an organic polymer (having a tree-like structure). The results show that the average thickness of the film is 90 nm.
The film allows the lithium-sulfur mixture in one place, and organize them to flow to the electrolyte, the battery performance degradation. Through this mechanism, scientists have demonstrated that they can extend their life cycle without compromising lithium-sulfur battery performance. "The best part is that with these materials, we are able to make a stable cell with a very small amount of film," said Batista.
Jianbing Jiang, a co-author of the paper and postdoctoral researcher at the Institute of Energy Science at Yale University, emphasizes that the hybrid film is made of a commercially available base material that makes it inexpensive and easy to use on a large scale.
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