N101-054 TITLE: Novel Methods to Improve Performance of Silver-Zinc Batteries

TECHNOLOGY AREAS: Ground/Sea Vehicles

ACQUISITION PROGRAM: PMS399/PMS-NSW ASDS, JMMS, SDV and SWCS

OBJECTIVE: To develop innovative large format Silver-Zinc cells and batteries that can provide total capacities in excess of 1 Mega-watthour (MWh) per cycle for greater than 36 cycles and two years of operation without requiring replacement.

DESCRIPTION: Silver Zinc (Ag-Zn) battery systems are more volumetric and gravimetrically efficient than many other types of rechargeable battery systems (such as Lead Acid). They even can provide close to the energy storage capacity of many types of Lithium Ion (Li-Ion) batteries as well, but do not carry the same level of risk of energetic failure of battery cells. However, the primary disadvantages of Ag-Zn batteries are their limited cycle and calendar life and low charge rates. Cycle life for the highest energy density designs can be below 20 cycles, and charge times of 36 to 72 hours are often required. These batteries also have the disadvantage of requiring systems to purge evolved hydrogen and oxygen gases. Recent research Ag-Zn batteries has not focused much on the large format batteries this topic covers.

Ag-Zn battery cells experience several failure modes that can likely be greatly reduced by novel membrane, electrolyte or electrode materials or coatings. This topic seeks innovative methods to improve the inherent efficiency and lifetime of very large scale Ag-Zn batteries. This solicitation seeks innovative improvements in battery and cell technologies that can be incorporated into large-scale Ag-Zn battery and cell technologies (e.g. possible alternate electrodes, electrolyte, or cell separator membrane materials) which reduce the likelihood and effect/ impact of cell failure modes (e.g. oxidation and degradation of separators, silver penetration, and zinc dendrite and oxalate crystal formation). Proposed improvements and modifications must be incorporable while still maintaining cell-level specific energy in the range of 150 to 200 Wh/kg and cell energy density in the range of 300 to 400 Wh/l. The offeror shall target cell sizes ranging from 100 Ah to 500Ah or larger, with cycle/service life targets in excess of 36 cycles and 5 years.

This solicitation also seeks innovative assembly-level and system-level approaches which can help increase the service life of these batteries (e.g. by performing cell balancing, improving cell packaging and thermal handling, or other similar operations). Approaches can include electronic, mechanical, chemical, thermal methods or otherwise, but should be applicable and effective in addressing the unique needs of high voltage (260 V) and high capacity systems (in excess of 1 MWh), while maintaining system-level specific energy in the range of 120 to 160 Wh/kg and system-level energy density in the range of 250 to 350 Wh/l. Assembly-level and system-level approaches should also consider the need in many situations to break high capacity systems into multiple modular units (e.g. 50 to 100 kWh) which are installed inside pressure vessels for underwater use, with multiple cycles performed while installed in the pressure vessels.

PHASE I: Perform basic research and development to investigate alternative electrode, electrolyte and/or separator materials that will greatly reduce the likelihood of potential cell failure modes. In a laboratory environment, conduct feasibility studies of proposed innovative new material or design concepts. Demonstrate by engineering analysis that the materials and design concepts are scalable, and will improve the efficiency, charge time, and life of large scale Ag-Zn battery applications in high voltage (260 V) and high capacity systems (in excess of 1 MWh/cycle), without sacrificing performance significantly. Analyze these designs based on factors listed above, including reliability, efficiency, weight, EMI considerations, size, charge time, and predicted cycle life, in addition to the inherent safety of the battery system itself. The Technology Readiness Level at the end of Phase I is expected to be TRL-3 at a minimum.

PHASE II: Implement and verify the design and concepts from Phase I in both bridge and full-size cells and bridge and full-scale multi-cell modules. Develop prototype battery management system to safely regulate the cells during charge and discharge evolutions. Build prototypes, and conduct proof-of-concept testing in a laboratory environment. This testing should include long term cycle testing and safety testing similar to the tests listed in reference 1 to assess the safety and performance of the new design. Long-term cycle testing shall last at least 1/2 year prior to end of Phase II. Validate efficiency and energy and power density storage of prototype systems. Develop final Engineering Development Model (EDM) multi-cell module capable of being tested in a shipboard environment (NOTE: testing in a real-world environment will not be conducted during Phase II). The Technology Readiness Level at the end of Phase II is expected to be TRL-6.

Vendors shall submit a business plan for the commercialization of the technology developed under this topic. The Small Business Administration�s web site www.sba.gov provides guidance, examples, and contact information for assistance.

PHASE III: Conduct shipboard testing and suitability analysis of the EDM battery systems, including shock, vibration, and Scope of Certification testing for Navy Deep Submergence System use. Validate safety and efficiency of EDM system in a true at-sea environment. Develop commercialization, and transition plans for full-scale shipboard implementation. Develop technical and user manuals, end-user training programs, logistics/ repair support plans, and troubleshooting and repair guides. Conduct initial end-user training and operator certification.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: The component and technology improvements sought here could be useful in commercial applications where high energy density is the main driver for energy storage needs. Examples would be space applications, ocean exploration, offshore oil rig inspection, UAVS, and robotics.

REFERENCES:
1. Karpinski A. P., Makovetski B., Russell S. J., Serenyi J. R., Williams D. C. "Silver-zinc: status of technology and applications," International Power Sources Symposium No21, Brighton, ROYAUME-UNI (10/05/1999) 1999, vol. 80, no 1-2 (331 p.) (7 ref.), pp. 53-60. http://cat.inist.fr/?aModele=afficheN&cpsidt=1862607

2. James Skelton and Roberto Serenyi. "Improved silver/zinc secondary cells for underwater applications," Journal of Power Sources, Volume 65, Issues 1-2, March-April 1997, Pages 39-45. The 20th International Power Sources Symposium. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TH1-3S9K2PW-9&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1016811904&_rerunOrigin=scholar.google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=897b7293dce423450654106b3f368cb8

3. R. M. Dell. "Batteries: fifty years of materials development," Solid State Ionics Volume 134, Issues 1-2, 1 October 2000, Pages 139-158. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TY4-41J69KY-H&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1016813108&_rerunOrigin=scholar.google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=529ef2dfd29c449a3b08d1f94d8872bc

KEYWORDS: Silver; Zinc; Battery; Capacity; Cycles; Safety

** TOPIC AUTHOR (TPOC) **

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