For a long time, for batteries using traditional materials, how lithium ions diffuse into and out of the alloy negative electrode has been a factor that limits how much energy the battery can carry. Too much ion current will cause the anode material to expand and contract during the charge and discharge cycle, causing mechanical degradation and shortening the battery life. In order to solve this problem, researchers have developed a hollow "yolk shell" nanoparticle anode material that can adapt to the volume change caused by the ion current. However, the manufacturing process of this material is very complicated and expensive.
According to foreign media reports, recently, researchers at Georgia Tech, ETH Zürich and Oak Ridge National Laboratory have discovered that antimony nanocrystals are small enough It can spontaneously form uniform voids during migration and reversibly fill and vacate during the cycle, allowing more ions to flow through without damaging the negative electrode.
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 regarded as a promising option. The current problem is , Direct large-scale synthesis and commercialization of this hollow nanostructured material is challenging and costly. Our findings can provide a simpler and easier process, and to some extent improve the performance of the material, 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 the model to establish a theoretical framework to explore why nanoparticles spontaneously form voids without shrinking during lithium migration in the battery.
The ability to form reversibly filled hollow particles during battery cycling only occurs in oxide-plated antimony nanocrystals with a diameter of less than 30 nanometers. The research team found that this behavior stems from a natural, elastic oxide layer. When lithium ions flow into the negative electrode's lithiation process, the oxide layer will initially expand, but there will be no mechanical shrinkage, because antimony will form voids during the ion removal process. This process is called delithiation. This discovery is quite surprising, because earlier studies of related materials focused on larger particles. These particles will expand and contract instead of forming a hollow structure.
Since antimony is relatively expensive, it has not yet been applied to commercial battery electrodes. However, McDowell believes that some lower-cost materials can also spontaneously hollow out, such as tin. Next, the researchers will test other materials and explore commercial promotion paths. Matthew McDowell said: "Test other materials to see if they will have a similar hollow mechanism, which will help expand the range of materials that can be used for batteries. The small test batteries we make have good charge and discharge performance, so we plan to Related materials are further evaluated in large batteries."
Although the cost is higher, self-hollow antimony nanocrystals (self-hollowing antimony nanocrystals) can also be applied to sodium ion and potassium ion batteries. These two emerging battery systems are for further study. (Elisha)
Smart Appliances,Smart Home Appliance,Mini Smart Kitchen Appliance,Smart System Home Appliance
ChangChun E-vida Technology Co.,ltd , https://www.evidatech.com