Geshi Auto News? For a long time, for batteries using traditional materials, how lithium ions diffuse into and out of the alloy cathode has always been a factor limiting how much energy the battery can carry. Excessive ion current will lead to the expansion and contraction of cathode materials in charge and discharge cycles, resulting in the decline of mechanical properties and shortening the battery life. In order to solve this problem, researchers developed a hollow "yolk shell" nano-particle negative electrode material, which can adapt to the volume change caused by ion flow, but the manufacturing process of this material is very complicated and expensive.

According to foreign media reports, Georgia Institute of Technology (Georgia? Tech), and the Federal Institute of Technology Zurich (ETH? Zurich) and Oak Ridge National Laboratory (Oak? Ridge? National? Laboratory) researchers found that antimony nanocrystals small enough can spontaneously form uniform gaps during lithium migration, and can be reversibly filled and emptied during the cycle, allowing more ions to flow through without damaging the cathode.

Researcher Matthew? Mcdowell said: "People have been studying hollow nanomaterials for some time. This material can improve the life and stability of high energy density batteries and is considered as a promising choice. At present, it is challenging and costly to directly synthesize and commercialize this hollow nanostructure material on a large scale. Our findings can provide a simpler and easier process and improve the material properties to a certain extent, which is close to the specially designed hollow structure. "

The researchers used a high-resolution electron microscope to directly observe the reaction of the battery on the nanometer scale. The team also used this model to establish a theoretical framework to explore why nanoparticles spontaneously form gaps during lithium migration of batteries without shrinking.

The ability to form reversibly filled hollow particles during battery cycle only appears in antimony oxide-plated nanocrystals with a diameter less than 30 nm. The research team found that this behavior originated from an elastic natural oxide layer. When lithium ions flow into the negative electrode, the oxide layer will expand at first, but it will not shrink mechanically, because antimony will form holes in the process of desorption, which is called lithium removal. This discovery is quite surprising, because the early research on related materials mainly focused on larger particles. These particles will expand and contract instead of forming a hollow structure.

Because antimony is expensive, it has not been applied to commercial battery electrodes at present. However, mcdowell believes that some low-cost materials, such as tin, can also be hollowed out spontaneously. Next, the researchers will test other materials and explore the road to commercialization. Matthew? Mcdowell said: "Testing whether other materials have similar hollow mechanism will help to expand the range of materials that can be used in batteries. The small test battery we made has good charge and discharge performance, so we intend to further evaluate related materials in larger batteries. "

Although the cost is high, self-hollow antimony nanocrystals (self-hollow? Antimony? Nanocrystals) can also be applied to sodium ion and potassium ion batteries. These two new battery systems need further study.

This article comes from car home, the author of the car manufacturer, and does not represent car home's position.