SBIR-STTR Award

BST Systems proposes a development program that will result in the elimination of the deficiencies of the silver zinc chemistry: Specifically, the program will result in large format silver zinc cells and batteries that have longer life, longer cycle life, are sealed and will require minimal maintenance requirements. Energy densities and power densities will equal or exceed that of lithium ion, however, unlike the lithium ion electrochemistry, they will be safe. This new technology will greatly benefit the Navy as they will have available a safe high energy electric propulsion capability utilizing a safe high energy large format battery. In the recent past, a vast amount of technologic advances have been made in electrochemical and fuel cell technologies with synthetic polymer membrane development. BST proposes to incorporate these technologies into large format silver zinc cells to achieve: a) An increase in calendar life and cycle life by eliminating the cellulosic separator systems b) An increase the cyclic capacity retention by significantly reducing the loss of negative electrode active material. c) The production of a maintenance free product by sealing the cell. This is achievable by reducing internal cell corrosion, reducing and recombining gaseous by-products and automatically micro-managing the charge process.

Benefit:
The goals of BST Systems program is to develop a rechargeable silver zinc cell with the following attributes: A wet life greater than 5 years A cycle life greater than 100 high energy cycles at (100% DOD) with a capacity retention of greater than 90% An improvement in volumetric energy density of 20% An increase in gravimetric energy density of greater 20% A cell with improved zinc electrode stability A cell which operates sealed thus eliminating the need for purge gases and increased maintenance costs. The benefits of such a cell and design concept are obvious. Because of the greater number of high capacity useful cycles, the cost per cycle of the product would be reduced thereby reducing the operational cost to the user. Greater wet life would enhance vehicle and/or weapon availability to the user and would also alleviate logistical issues. Maintenance costs would be drastically reduced. The resulting technology would be applicable and be of benefit to all Navy silver zinc applications. The design of a sealed silver zinc cell would reduce maintenance costs, eliminate the use of purging systems and allow the silver zinc chemistry to be utilized in other applications which, up to now, have not been possible. Further, such a product would also render itself to non-military commercialization.

Keywords:
Battery, Battery, silver, capacity, Zinc, Cell Sealing, Cycling Improvement

BST Systems has been engaged in IR&D Projects #7079, #7103 and SBIR Phase I Topic #N101-054 targeting sealed-cell operation, separator improvement, and negative electrode enhancement. The aim is to develop a nearly maintenance-free, sealed-cell that offers overall performance improvement in terms of cycle life and wet life. The systematic approach included analysis of non-cellulosic separators, novel negative electrode/electrolyte additives, the development of catalytic composites for gas consumption, and the development of a charge control management system that minimizes gas production. The objective is to develop a battery system that provides greater than 2 years wet-life, greater than 50 cycles with 70% capacity retention, and sealed operation for periods of at least 10 cycles without maintenance. In Phase I, novel materials and technologies were evaluated independently. The proposed Phase II approach is to optimize and combine the technical improvements identified in Phase I into a final large format cell design and perform long term cycle testing of the final design.

Benefit:
The goal of BST Systems program is to develop a rechargeable large format silver zinc cell with improved wet life, cycle life and capacity retention while operating at 100% depth of discharge. The improved design would also operate in a sealed condition thus eliminating the need for purge gases and increased maintenance costs. The benefits of such a cell and design concept are obvious. Increasing the number of useful cycles at high capacity would reduce the cost per cycle of the product thereby reducing the operational cost to the user. Greater wet life would enhance vehicle and/or weapon availability to the user and would also alleviate logistical issues. Maintenance costs would be drastically reduced. The resulting technology would be suitable for and of benefit to all Navy silver zinc applications. The design of a sealed silver zinc cell would reduce maintenance costs, eliminate the use of purging systems and allow the silver zinc chemistry to be utilized in other applications which, up to now, have not been possible. Further, such a product would also be open to use in non-military commercialization.

Keywords:
Zinc, Sealed Cell, capacity, Cycling Improvement, silver, Hydrogen Gas Consumption, Battery