Probing the Effect of Ion Insertion on the Mechanical Stability of High Capacity Nanocomposite Anodes

University Of Florida, Gainesville FL

Investigators

Abstract

Silicon based electrodes are the most promising next generation anodes for Li-ion batteries due to their high energy storage density, however, they have not been commercialized because they fail due to mechanical fracture very quickly. A similar rapid failure due to mechanical instability must be overcome in commercializing tin anodes for sodium-ion batteries. The material with the most promising microstructure that can limit such fracture or instability is that of silicon or tin nanoparticles coated with a matrix. The present award will use an integrated experimental-computational approach to investigate the mechanical behavior of these nanocomposites and will predict the interplay between the size of the tin or silicon particles, the matrix material, and battery performance. The successful end to the research will promote the progress of interdisciplinary science and, on the application side, provide design guidance for commercializing next generation electrodes. The resulting lithium-ion batteries will have a longer lifetime and smaller dimensions than the current ones, and will have a wide range of applications from cell phones to electric vehicles. Sodium-ion batteries occupy larger volumes than lithium-ion and therefore will be used in combination with renewable energy sources. This project will, therefore, also allow for a more sustainable and environmentally friendly US economy, thus advancing the national health, prosperity, and welfare. The results will be disseminated to high schools and science museums to motivate young students, especially from minorities, to study science and engineering. To fully understand the mechanical behavior of nanocomposite anodes an interdisciplinary approach will be followed which combines detailed electrochemical experiments along with multiphysics modeling. The specific focus is to determine the effect of lithium-ion (or sodium-ion) insertion and de-insertion on silicon and/or tin nanoparticles coated with polymers. A new computational model will be formulated and implemented, which will allow for the prediction of the appropriate combination of particle size and polymer coating that will inhibit damage at the interfaces of the nanocomposite anodes during battery operation. Based on the theoretical predictions new anodes will be fabricated and tested. Particularly high-resolution electron microscopy will be able to capture the extent of damage at the particle-polymer interface and verify the model. After experimental validation, design guidance will be available for battery developers to fabricate next generation electrodes for both lithium and sodium ion batteries. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.