Liquid Catholyte Investigations for Safer Storage of a Li Primary Battery

The close proximity of the electrode materials is a design risk for commercial off the shelf (COTS) Li batteries.  COTS Li batteries can off gas and ignite if the electroactive materials are inadvertently mixed by events such as thermal abuse, crush, penetration, and shock.  Crew safety on US Navy ships and submarines critically depends on minimizing the probability of exposure to toxic gases and fire.  The Naval Undersea Warfare Center (NUWC) is investigating a primary Li battery design for undersea applications that is, in principle, safer to store and transport than COTS batteries.  In this approach a liquid catholyte is stored separately from a Li metal anode.  The catholyte is added to the anode housing immediately prior to off board deployment of the energy section.  With this configuration the electroactive materials can be stored separately and more safely than in COTS batteries.  NUWC has recently begun investigating slurry catholytes¹ comprised of solid redox active cathode materials and electronically conductive carbon powders dispersed in a nonaqueous electrolyte.  Our goals are high volumetric charge capacity, high voltage, good power density and a “pumpable” rheology.  These properties are significantly affected by the formulation of the slurry such as the choice of redox active material, the volumetric solids concentration of the redox active and carbon materials, the interaction between the particles, and the particle size distributions.  This talk will discuss NUWC’s separated anode / catholyte battery concept, the tradeoffs of various electroactive cathode materials, and the results of catholyte investigations and their expected impact on the performance of a Li-slurry catholyte primary battery.     

1) M.Duduta., B.Ho, V.C. Wood, P. Limthongkul, V. E. Brunini, W. C. Carter, and Y-M Chiang, Semi-Solid Lithium Rechargeable Flow Battery, Adv. Energy Mater. 2011, 1, 511–516