The objective is to develop rechargeable lithium batteries with a factor often improvement in cycle life, a factor of four improvement in compactness over present rechargeables, and reduced manufacturing cost. All three are important for implantable medical devices for cardiomyoplasty, pacemakers, neurological simulators, and other applications. Patient benefits include improved reliability, quality of life, and comfort as well as elimination of surgical procedures in a large patient population. Degraded performance and limited lifetime (150 cycles) in prototype lithium batteries are caused by loss of physical contact at various interfaces in the composite cathodes. The innovation is a thermal spray process for depositing cathodes which are films of pure oxides, eliminating the troublesome interfaces found with prototype composite cathodes. The Phase I plan is to thermal-spray cathodes, assemble sample lithium batteries with polymer electrolytes, and cycle the batteries to confirm performance. LiCoO2 cathodes will be prepared in the demonstration. Cycle life of lithium/polymer batteries could improve by a factor of ten or more. Volumetric energy density of the cell would improve by a factor of four over current NiCd or NiMH batteries and a factor of two over other lithium battery prototypes (with composite cathodes).
For rechargeable lithium/polymer batteries, Medtronic Inc. identifies their applications of interest as cardiomyoplasty, pacemakers, and neurological simulators. Other possible applications include total artificial hearts, defibrillators, respiratory assist, urinary control, and hand manipulation. The present commercial market for pacemakers alone is 350,000 units per year. Other commercial markets are 5 million units per year for notebook computers and 7 million units per year for cellular phones, according to Alliant Techsystems Inc. Both companies have expressed interest in licensing a successful cathode- film manufacturing process developed by Creare as Dart of the various battery products which each will manufacture.
