Development of lithium and lithium-ion batteries for implantable medical devices

Implantable medical devices and applications have been used to treat many different medical conditions. Those applications include pacemakers, implantable cardioverter-defibrillators (ICDs), neurostimulators and hearing loss. Recently, the advent of new medical devices and applications such as cardiac resynchronization therapy defibrillator (CRT-D), left ventricular assist devices (LVADs) and total artificial heart (TAH) demands more high power and high energy. Those devices require a long life, reduced size and ultimately lower cost. Lithium or lithium-ion batteries is a suitable chemistry to meet the requirements of implantable device applications, however, there is an increase demand to improve the performance.;A lithium primary battery using a hybrid electrode of a hybrid electrode of Li1.2V3O8 and CFx were evaluated with a goal of the improvement of its performance at high rates. Li1.2V3O8 has a higher potential than CF x at the beginning of discharge, good rechargeability, high power and good low temperature performance. The hybrid chemistry of Li 1.2V3O8 and CFx is able to improve a lower initial voltage delay, enhanced pulse capabilities and better storage performance. XRD analysis confirmed that CF x charged Li1.2V3O8 during storage. The potential difference drives CFx to chargeLi1.2V3O8 to the single phase range, where Li1.2V3O 8 exhibits high lithium diffusion rate and the lowest polarization.;A lithium ion battery with the deep discharge tolerance was studied. The mechanism of the deep discharge capacity decay was evaluated with a goal of the improvement of deep discharge tolerance in the implantable lithium-ion batteries. Implantable lithium batteries are needed that can be stored at body temperature with long periods of non operational conditions. Conventional lithium ion chemistries are incapable of deep discharge without capacity loss. In this study, anodic potentiodynamic polarization, cyclic voltammetry and electrochemical characterization with 2032 coin cells were used to define three potentials that play critical roles in improving deep discharge capability. First, the zero volt crossing potential (ZCP) is the potential of the negative electrode when the battery voltage is zero. Second, the substrate dissolution potential (SDP) indicates the potential at which the negative substrate begins to corrode. Finally, the film dissolution potential (FDP) is the potential at which the solid electrolyte interface (SEI) decomposes. The ZCP must be kept below the SDP and FDP, otherwise damage to the negative electrode will result in capacity loss. The improvement of deep discharge characteristics in the lithium ion chemistry will be used in a wide range of applications since batteries need not be kept charged and can be left unattended for long periods.