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DoD 2013.B STTR Solicitation

Agency: Department of Defense
Branch: Defense Microelectronics Activity
Program/Year: STTR / 2013
Solicitation Number: 2013.B
Release Date: July 26, 2013
Open Date: August 26, 2013
Close Date: September 25, 2013
DMEA13B-001: Electrochemical Micro-Capacitors Utilizing Carbon Nanostructures
Description: TECHNOLOGY AREAS: Materials/Processes, Electronics The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), which controls the export and import of defense-related material and services. Offerors must disclose any proposed use of foreign nationals, their country of origin, and what tasks each would accomplish in the statement of work in accordance with section 3.5.b.(7) of the solicitation. OBJECTIVE: Development of a non-Faradic, thin film, electrochemical capacitor-based energy storage system utilizing a nano-structured carbon/ ionic liquid material system with a gravimetric energy density greater than 100 Wh/kg. Novel device architectures such as 3-dimensional or interdigitated arrays are primary areas of interest. Process compatibility with lithographic techniques common to commercial semiconductor processes and printable circuit technology are areas of further interest. DESCRIPTION: Electrochemical capacitors, informally known as ultracapacitors, are energy storage devices that combine the high energy storage capability of batteries with the high power delivery capability of capacitors. Ultracapacitors have a demonstrated superiority over conventional batteries, in terms of higher power delivery and longer cycle life. The materials utilized in such a device play a prominent role in determining the achievable energy and power densities. High-surface area activated carbon is currently the predominate material used to form the electrodes in macro scale ultracapacitors. Charge storage in ultracapacitors is generally evaluated by capacitance, which in turn is dependent on the electrode/solution interface. Typical carbon electrodes exhibit poor electrolyte accessibility (low mesoporosity) as a consequence of small pore size in the carbon compared to the larger size of the solvated ions in the aqueous electrolyte. However, recent developments have shown that utilization of carbon allotropes, such as carbon nanotubes (CNTs) and graphene, will result in an electrode with much higher mesoporsity. The manifestation of increased mesoporosity is increased capacitance which results in higher energy density and specific energy. Additionally, carbon allotropes can be chemically modified to increase pseudocapcitance. Graphene monolayers are extremely flexible; thus, micro ultracapacitor arrays created with graphene can be readily incorporated into flexible electronic structures. A limiting factor in the miniaturization of carbon nanostructure-based ultracapacitior arrays is a relatively low volumetric energy density (Wh/L) due to the rather poor packing density of structures such as tangled CNTs. Typically, the volumetric energy density of current generation CNT-based ultracapacitors is many orders of magnitude lower than mainstream energy storage devices. Thus opportunities for miniaturization of macro-scale ultracapacitors exist with novel designs that strive to minimize intrinsic components such as current collectors and separators that do not directly contribute to the cell energy storage. The successful solution will meet the following performance metrics: - Utilize a material system that delivers gravimetric energy densities greater than 100 Wh/kg - A sustained output voltage of 3 V. - Minimal performance degradation over a temperature range of -55oC to 125oC - A minimum volumetric energy density of 400 Wh/L - Demonstrate no discernible performance degradation to output power and voltage after undergoing a minimum 2,000 and a maximum of 100,000 full charge/discharge cycles. - A minimum useable lifetime of 5 years If any of the goals listed above cannot be met, the contractor will present relevant research and establish parameters that are attainable. PHASE I: The goal of Phase I is to demonstrate, by simulation and direct measurement, a carbon nanostructure/ ionic solution material system that has a gravimetric energy density greater than 100 Wh/kg and an associated volumetric energy density of at least 400 Wh/L. A high level of consideration will be given to achieving the maximum volumetric energy density. The results of a rigorous, analytical simulation methodology shall be substantiated by direct measure of material samples. The simulated and measured data results shall constitute a deliverable item. PHASE II: Phase II will result in the creation of prototype micro ultra-capacitor cell arrays. Rigorous analytical simulations utilizing both the material system's physical and electrical parameters will be substantiated by direct measure of the prototype cells to demonstrate that the designed ultra-capacitor cells are capable of meeting the performance criteria listed in the description section for the final energy storage device design. Consideration will be given to designs that enhance miniaturization by minimizing intrinsic components that do not directly contribute to energy storage. Production techniques utilized will be compatible with the lithographic techniques found in commercial integrated circuit fabrication processes. The simulated and measured data that prove prototype conformance shall constitute a deliverable item. PHASE III: Phase III will conclude with the delivery of fully developed and verified pre-production miniaturized energy storage devices capable of meeting all of the performance and process integration metrics described in the preceding sections of this document. Additionally, documentation shall be provided from a certified testing facility that the pre-production devices have undergone and passed environmental testing in conformance with Mil-Std 883. Additional government and commercial customers and applications for the devices will be identified.