Stuart Santee

Li-Ion Electrolytes Containing Ester Co-Solvents for Wide Operating Temperature Range

As part of our continuing efforts to develop advanced electrolytes to improve the performance of lithium-ion cells, especially at low temperatures, we have identified a number of electrolyte co-solvents that can be incorporated into multi-component electrolyte formulations for enhanced performance, especially at very low temperatures (down to -70oC). In the current work, we investigated a number of ester co-solvents, namely methyl propionate (MP), ethyl propionate (EP), methyl butyrate (MB), ethyl butyrate (EB), propyl butyrate (PB), and butyl butyrate (BB), in multi-component electrolytes of the following composition: 1.0 M LiPF6 in ethylene carbonate (EC) + ethyl methyl carbonate (EMC) + X (20:60:20 v/v %) [where X = ester co-solvent]. These electrolytes have been optimized to provide good low temperature performance (down to -60oC) while still offering reasonable high temperature resilience to produce the desired wide operating temperature systems (-60 to +60oC). This has primarily been achieved by fixing the EC-content at 20% and the ester co-solvent at 20%, in contrast to the previously developed systems.

Optimizing Electrodes for Lithium-ion Cells

Selection of active electrode materials is only the first step in the cell design and manufacturing process. In order to achieve the best cell performance, the “non-active” components need to be carefully selected both qualitatively and quantitatively. Especially in high-end applications, the electrode formulation optimization process is nontrivial and seriously impacts the cell’s performance. Achieving the high performance limits, such as extremely high power, very high temperatures, or very long life, require thoughtful and deliberate approach to electrode formulation optimization.

Next Generation Lithium-ion Cell Chemistry for Space Applications

Yardney Technical Products (YTP) has a long history of supplying high performance batteries for demanding military and aerospace applications. With its start in the 1940’s developing Silver/Zinc batteries for Navy applications through to the start of its Lithium-ion technology in the late 1990’s, Yardney has successfully delivered many chemistries and designs specifically tailored to the exacting requirements of a broad range of applications. Yardney has recently developed a Next Generation Lithium-ion chemistry to continue supporting planetary, satellite, and deep space missions, as well as NASA’s next manned mission capability, the Orion Multi-Purpose Crew Vehicle (MPCV). Enhancements in this new chemistry include increased energy density, lower impedance (to support higher rate capability) and improved high temperature stability. Initial results from Next Generation cell tests are demonstrating up to 20% increase in capacity (for a fixed cell volume) as well as improvements in rate capability, stability and long-term performance. This Next Generation chemistry has already been incorporated into many terrestrial applications, including UAVs and torpedo systems, and is being qualified for both Manned and Unmanned space applications. Nomenclature Ah = ampere hour DoD = Depth of Discharge LNCO = Lithiated Nickel Cobalt Oxide LNCA = Lithiated Nickel Cobalt Aluminum Oxide MCMB = Mesocarbon Microbeads SOC = State of Charge V = voltage (DC) Wh = watt hour

Next Generation and Domestically Produced Active Materials for Li-Ion Cells

Yardney Technical Products (YTP) has established comprehensive programs to develop and test next generation and domestically produced, high energy, high power and long life anode and cathode materials. This effort was undertaken to support Yardney’s diverse military and aerospace customer base to ensure design heritage and provide demonstrated performance enhancements for new applications. The initial effort includes partnering with several domestic partnerships, focusing on both anode and cathode efforts, as well as investigations into electrolyte and separator materials. The initial effort has focused on the development of mixed metal oxide cathode materials along with cathode materials that include surface stabilizing coatings. The cathode surface stabilization benefits from YTP’s extensive high voltage cathode development efforts in which various high voltage cathodes are being evaluated. The initial testing is demonstrating stability at very high discharge rates (100C continuous, 400C pulses) and low and high temperatures (from -30°C to 85°C). In addition, the cathode materials are being tested in high specific energy designs to support lower rate, moderate temperature applications such as Unmanned Underwater Vehicles (UUVs). This paper presents the results of these initial material developments with comparisons to the state of the art commercial (foreign produced) materials.

Advances and Field Testing Results for Military and Aerospace Lithium Ion Batteries

Lithion, Inc. (a division of Yardney Technical Products, Inc.) has designed, qualified and delivered custom Lithium Ion batteries for numerous commercial, military and industrial applications. Notably, Lithion has supplied the batteries for the ongoing Mars Rover missions and is currently delivering additional lithium ion battery shipsets for continued conversion of the B2 Stealth bomber from NiCad to Lithium Ion. In addition, Lithion delivered an 8-ton, 300 V, 1,200,000 Wh Lithium Ion battery to NAVSEA to support the Advanced Seal Delivery System (ASDS). This is believed to be the largest Lithium Ion battery ever delivered. Ongoing programs include the X-37 Space Plane, Various Satellites (XSS-11, NEXTSat), a human implantable battery, and numerous underwater applications. These programs are in addition to an ongoing research effort to develop cells and batteries that would be capable of supporting proposed directed energy weapons. These widely varied applications offer significant insight into the potential of lithium ion technology. This paper reviews the general performance requirements of these applications and the performance of the batteries that support these applications.