Microstructural Control of Nano-Porous Metal/Metalloid for Battery Applications

Description

Lithium-ion batteries such as the one in our cell phones store energy by transferring lithium ions between the materials in the two electrodes. How fast the battery can be charged and discharged depends on the particle size of the materials – smaller particlescan accept lithium ion faster and thus allow the use of larger current. Therefore, there have been many research works focusing on nano-sizing battery materials. However, nano-particles are difficult to handle and manufacture from an industrial point-of-view.They also have large surface area for side reactions and low packing density, which prevent their practical use in batteries.Nano-porous materials having a Swiss cheese or a sponge-like structure can be a good compromise. Apart from having smaller transport lengths, the pores can also allow penetration of electrolyte and can accommodate volume changes when incorporatinglithium ions into the material during charging. Porous materials can be fabricated by first making an alloy with two elements, and then selectively removing one of the more reactive elements by methods such as etching and vacuum annealing/distillation etc.The objectives of this project are to fabricate nano-porous antimony (Sb), silicon (Si) and tin (Sn) with micron-sized particles to increase the amount of stored energy in lithium-ion batteries. Our plan is to control the particle size, porosity, pore size distribution and surface area of the nano-porous materials to optimize the corresponding battery performances. This is one step further than previous works, which only show the formation of nano-porous materials without much systematic control. We plan to achieve our objectives by fine-tuning the microstructure of the initial alloys through controlling the concentration of the alloying materials and cooling rate during solidification. This is a well-known process in metallurgy and will be applied here for energy storage applications. We expect the technologies from the development of nano-porous materials in this project can also be applied to other areas such as gas adsorption,catalysis, drug delivery, etc. in the future.