Feasibility Study for Large-Format Sodium-Ion Emergency Power Batteries for Minuteman III ICBM

The Air Force Nuclear Weapons Center (AFNWC) seeks to upgrade the emergency power systems for the Minuteman III intercontinental ballistic missiles (ICBMs). Lithium-ion batteries (LIBs) are the leading candidate for this application. However, their safety concerns pose a critical challenge for sensitive munitions applications, including the risk of fires caused by internal electrical short, overheating, crushing, or overcharge/over-discharge. AFNWC's requirements include improved storage/shelf life and operational (cycle) life.Ā The new battery system must also be cost-effective to acquire while meeting all the safety and performance requirements. We propose using sodium-ion batteries (NIBs) for this application, which are inherently safer than LIBs. Our initial chemistry will be based on a Na0.44MnO2 cathode, a hard carbon anode and a NaPF6-based electrolyte. This combination is capable of ~ 130 Wh/Kg. While the specific energy is less than that of a typical LIB, the static nature of the application and the need for a safer, lower-cost battery make NIBs an attractive option. Our Phase I proposal is focused on synthesizing a proprietary hard carbon anode material for the anode of the NIB. We plan to test our hard carbon materials in NIB half-cell configurations against sodium counter electrodes using NaPF6-based electrolytes. We then plan to develop the full cell during Phase II ¢ working with our cell partner ¢ Maxpower Inc. (an existing supplier of specialty batteries to the DoD). We have developed a patented process that utilizes the polymerization of an agricultural waste-derived furan compound to synthesize the hard carbon anode materials. The precursor materials are typically furfuryl alcohol and furfuraldehyde. This innovative approach provides a low-cost alternative to the usual hard carbon precursors currently used in industry (mostly petroleum pitch or coconut shell char). It potentially frees the industry's dependence on Chinese and Japanese hard carbon. There are no domestic suppliers of hard carbon today. Besides being from a renewable resource, our hard carbon has exceptionally low impurity levels, and is produced using a simple, scalable manufacturing process. Initial electrochemical testing of our hard carbon showed excellent performance. This proposal will continue that work ¢ focusing on the NIB anode application. Lockheed Martin MFS has expressed initial interest in evaluating our hard carbon technology in NIBs, as indicated in their letter of support. The University of Dayton Research Institute (UDRI) will characterize & test our hard carbons (SEM/EDS, XRD, Raman and electrochemical). UDRI's history of collaborating with the AFRL on cutting-edge defense technologies makes them an ideal academic partner for this STTR proposal.