SMOFC Battery Cathode
INVENTION: A novel battery cathode composition having a higher discharge capacity available from silver reduction at a potential above 3V compared to that of the current standard medical battery cathode SVO material.
ADVANTAGES: Batteries incorporating the new cathode exhibit a potential above 3 V for extended periods of time, critical to medical devices such as defibrillators. The cathode is devoid of vanadium, provides chemical stability and electrochemical performance.
SUMMARY: The medical battery industry desires cathode materials that can maintain a potential above 3 V for extended periods of time so as to optimize defibrillator function. The current standard cathode material in medical batteries is silver vanadium oxide Ag2V4O11 (SVO). Although SVO material has a high theoretical capacity of 450 mAh/g (milliampere hour per gram) based on Ag+/Ag and V5+/V3+ redox couples, not all of this capacity is accessible at practical voltages and the gravimetric capacity of SVO is not fully utilized in practical applications. Morever, a battery cathode free of noxious vanadium affording chemical stability and electrochemical performance is desirable.
A novel battery cathode composed of silver, molybdenum, oxygen, fluorine and chlorine (SMOFC) has been created. The cathode can be used in a medical devices, such as a defibrillator, e.g. implantable cardioverter defibrillator (ICD) battery, having a lithium metal anode. A cathode comprised of the dense SMOFC compound exhibits very high discharge rate capability driven by (i) an electronic conduction path via the silver ions network and (ii) a crystal structure displaying large three dimensional tunnels favorable for a high ionic conduction. Thus a SMOFC cathode is able to deliver a capacity as high as 106 mAh/g at D rate as compared to 4 mAh/g for a SVO cathode. Battery capacity at potential for the SMOFC, SVOF (Ag4V2O6F2) and standard SVO batteries are shown in Figure 1. The SMOFC and SVOF cathodes deliver capacity at higher battery voltage on the first 150 mAh/g capacity and therefore more power and consequently shorter capacitor charge times, critical to providing new shocks in case of continued arrhythmia. These significant features should advance medical device performance and reliablility.
STATUS: Synthetic methods for SMOFC have been identified to produce desired particle size material. A patent application has been filed.
Kenneth R. Poeppelmeier, Frederic Sauvage, Vincent Bodenez, Jean-Marie Tarascon
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