SBIR Phase I: Low Cost, High Capacity Lithium-Ion Batteries Based On Nano-Structured Silicon Anodes And Ionic Liquid Electrolytes

Silexta Inc., Austin TX

Investigators

Abstract

This Small Business Innovation Research Phase 1 project will introduce a novel method of manufacturing a high capacity Si nanowire anode for Li-ion battery applications. Si has the highest lithium absorption capacity of any anode material (4200 mAh/g) whereas the incumbent anode material in today's Li-ion batteries has a capacity of only 372 mAh/g. The adoption of Si anodes however, is limited by the fact that bulk Si pulverizes due to volume expansion during cycling. Nanostructured Si does not pulverize, however, the approaches to make nanostructured Si anodes are either expensive, or not suitable for mass manufacturing, or limited by specific capacity. The proposed method is estimated to be low cost, scalable for manufacturing, and does not suffer from any of the technical limitations of current technologies used to fabricate anodes based on nanostructured Si. The researchers also propose to optimize the nanowire morphology and architecture for maximizing the anode capacity and enabling it to withstand more than 1,000 cycles with sufficient capacity retention. Furthermore, the researchers propose to integrate an ionic liquid electrolyte with the Si nanowire anode, which is expected to show high voltage stability. The broader impact / commercial potential of this project is truly transformational. This research will lead to a better understanding of electrochemical reactions in cells utilizing Si nanowire anodes. The novel approach to fabricate the anode may find use in other technologies such as in thermoelectric devices, gas / chemical sensors, and biomedical devices. The commercial impact of this low-cost technology is also expected to be highly significant. The batteries with Si nanostructures reported to-date have used expensive methods to create nanowires and current collectors. The researchers envision that their unique and disruptive approach will make ultra-high capacity anodes (~3000 mAh/g) possible on a large scale. The increase in anode capacity will result in an estimated 50%-60% increase in energy density for the total battery pack. Since Li-ion batteries are expected to play an increasingly larger role in consumer device storage as well as in industrial and electric vehicle (EV) applications, this would have a tremendous social and environmental impact. For one, the range that EVs can travel without a charge will be extended, thereby leading to widespread adoption of EVs. The increased battery capacity will also lead to solutions for residential and grid storage wherever renewable energy is used.