This Small Business Innovation Research Phase I project will demonstrate the technical feasibility of using proprietary low-cost, nanostructured vanadium nitride (VN) based electrodes and an asymmetric cell architecture with aqueous electrolytes to manufacture high energy density supercapacitors. Currently available commercial products deliver 3-6 Wh/kg with power densities of 700 W/kg at a cost of ~$0.10 per Farad. The cost must be decreased by at least a factor of two for broader market acceptance, and the energy density improved to reduce the size of the supercapacitor. Successful completion of the proposed SBIR program will lead to next generation supercapacitors with energy densities that approach 15 Wh/kg, exceeding the current state of the art by a factor of 3, and costs that are as much as 10 times lower than those for currently available commercial devices. The superior performance and cost are derived from the use of inexpensive, base metal nitrides and oxides tailored to give high specific capacitance, aqueous electrolytes that enable fast, efficient high power cycling, and an asymmetric cell design that maximizes the operating potential window. This combination of performance and cost will enable significant expansion in the use of supercapacitors for a number of important applications.
The broader impact/commercial potential of this project lies the improvements in energy density and reductions in cost. These advances will enable the use of supercapacitors for power management solutions for a number of energy storage systems. Commercial applications could include use in hybrid electric vehicles for load-leveling during start-up, acceleration and regenerative braking, memory back-up in mobile phones, and uninterruptible power supplies. Transportation and smart grid applications represent large markets with >30% annual growth each. The automotive supercapacitor market totaled $55M in 2009 and could grow to $243M by 2015 fueled by the demand for hybrid electric vehicles. The smart grid market for supercapacitors is forecasted to $3.6B in 2015 driven by peak-load management and regenerative braking for light rails. Devices developed during this SBIR program could support a transition from electricity produced from fossil fuels to carbon neutral electricity thus reducing our nation's production of greenhouse gases and dependence on foreign energy sources. Federal agencies including the Department of Defense will also benefit, in particular, for applications such as extended range vehicles, exoskeleton systems and electromagnetic armors. Finally, this project will give students at the University of Michigan an opportunity to participate in a commercialization effort.
Batteries are the principal devices used for most electrical energy storage, however, these devices are inefficient in pulsed and high power applications. Supercapacitors, another type of electrochemical energy storage device, could be used to improve the efficiency, extend the run times and increase the cycle-lives of batteries by handling these pulsed and high power events (see figure). Currently available commercial supercapacitors fall short of targets established for large-scale applications including power management for electrified vehicles during acceleration and regenerative braking, back-up power for telecommunications, and peak power buffering for renewable energy sources such as wind turbines. According to a report by Frost and Sullivan (2009) and based on customer feedback, the cost must be decreased by at least a factor of two and the energy density doubled for broad market acceptance. The principal performance and cost driver is associated with the electrode materials. Inmatech is developing next generation supercapacitor devices that incorporate low-cost, high-performance materials in proprietary designs. These devices use aqueous electrolytes that are safe (non-flammable) and inexpensive. Upon completion of the Phase I from NSF we have confirmed the feasibility of our proprietary cell design and achieved 50% higher storage capacities than commercially available devices. With optimization, the energy storage is expected to exceed that of the conventional carbon based supercapacitors by a factor of 3 (to more than 15 Wh/kg and 20 Wh/l) at costs that are 10 times lower. These improvements will enable markets for supercapacitors to rapidly expand. We are finalizing a license agreement with a major Tier 1 automotive supplier for further development and validation for multiple applications.