TECHNOLOGY AREAS: Ground/Sea Vehicles, Materials/Processes, Weapons

ACQUISITION PROGRAM: PEO(S), PMS-500, PMS-405, DD(X) Program Office, EMALS program

OBJECTIVE: Develop and demonstrate processed dielectric films with 10 J/cc capacitive energy storage capability and low dielectric loss.

DESCRIPTION: The Navy plans to develop the all electric ship. One motivation for this development is the realization that the power requirements of future Naval vessels will not be as dominated by propulsion as current ships and that it may be desirable to be able to transfer energy between uses. This will require storage and conditioning of vast amounts of power. Additionally, weapons, catapult systems and other military technologies that require pulses of power would require very large banks of dielectric capacitors. The goal of this effort is to develop dielectric materials appropriate for large pulsed power capacitors (wound metalized film) that have film level storage capability of greater than 10 J/cc to enable fully packaged capacitors that deliver >4 J/cc.

Current state-of-the-art dielectric capacitors that deliver 1 J/cc are based on polypropylene (PP), which derives its high energy density from a high breakdown strength. Other scalable thin film dielectric materials approaches, including PVdF and composites, have not yet shown the needed combination of processability, breakdown strength, and low loss for high energy density large scale capacitor manufacturing. Optimization of materials composition and processing conditions is required to mature these and other approaches to viable thin film dielectrics.

PHASE I: Develop a processable dielectric film with the capability to achieve 10 J/cc capacitive energy storage with discharge times of 10 milliseconds or less, less than 1% loss, thermal performance to 120�C, and a potential to incorporate a graceful failure mechanism. Throughout Phase I, the offerer will be able to submit a reasonable number of samples to the Navy for evaluation of the permittivity and dielectric strength. This is to aid the offer in the development of the dilelectric films and to allow the offerer to see how the Navy performs this characterization (breakdown results vary significantly with measurement techniques). The deliverables for Phase I will be 1 square foot of film for final performance testing, instructions for how to electrode the film, and a report on the potential scalability, cost, and performance and of this technology. Suggested approaches include but are not limited to polymer films, oriented polymer films, and composite films.

PHASE II: Work will include further development of the dielectric film, scaling of the material to lab scale film processing levels (> 2 to 5 kg of material) and incorporation of the dielectric film into a packaged capacitor that represents a subunit of a potential military capacitor. The fabrication issues will depend on the specific type of capacitor but may include synthesis scale-up, film processing for optimal breakdown properties, electroding procedures, design of the capacitor element, approaches to graceful failure, and packaging procedures. Several capacitors of appropriate size will be delivered to the Navy for full characterization. Cost estimates of the technology will be developed.

PHASE III: The goal of the phase II work is to mature the technology to a point in which an acquisition program (all electric ship particularly for the rail gun and electromagnetic launch applications) would be interested in transitioning to phase III development. Dielectric materials development was completed in phase II and film processing procedures should be well developed. Focus here is on designing and fabricating larger and larger capacitor subsections to demonstrate the manufacturability and performance of the technology.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Whereas large pulsed power capacitor banks and the strong emphasis on energy density are critical military needs, improved dielectric capacitors could find commercial applicability in power conditioning and back-up applications, hybrid vehicles, and other applications.

REFERENCES:
1. "A Dielectric Polymer with High Electric Energy Density and Fast Discharge Speed," B. Chu, et al., Science 313, 334 (2006)

2. "Phosphonic Acid-Modified Barium Titanate Polymer Nanocomposites with High Permittivity and Dielectric Strength," P. Kim, et al, Adv. Mater. 2007, 19, 1001-1005.

KEYWORDS: biaxially oriented polypropylene; polyvinylidene fluoride; polymer films; graceful failure; dielectric films; capacitors

TPOC: Paul Armistead
Phone: (703)696-4315
Fax: (703)696-0001
Email: [email protected]
2nd TPOC: Michele Anderson
Phone: (703)696-1938
Fax: (703)696-6887
Email: [email protected]
3rd TPOC: Ming-Jen Pan
Phone: (703)696-7021
Fax: (703)696-0934
Email: [email protected]

** TOPIC AUTHOR (TPOC) **

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