Silicon Whisker and Carbon Nanofiber Composite Anode

Physical Sciences Inc. (PSI) has successfully developed a silicon whisker and carbon nanofiber composite anode for lithium ion batteries on a Phase I program. PSI has demonstrated a technology readiness level of 3 with an anode composite capacity of greater than 1100 mAh/g for over 200 cycles (100% depth-of-discharge) at 1C using 2 mAh cells. This anode provides high capacity, high power, and improved cycle life at a competitive cost. Silicon is low cost and has a theoretical capacity of 4200 mAh/g but it has a limited cycle life. The nanocomposite design provides a synergistic improvement in reversible capacity and electrochemical cycling as a result of the unique silicon architecture and structural reinforcement provided by the nanofibers. In the Phase II program, PSI will increase cell size to 2.5 mAh and optimize cell design to further improve cycle life. PSI will deliver to NASA 2.5 Ah lithium ion cells with an energy density greater than 220 Wh/kg that is required by NASA's future robotic and human exploration missions. In collaboration with a battery manufacturer, PSI will also demonstrate that this anode technology is scaleable to reach industrial production level.