Study on lithium-ion secondary battery for implantable artificial heart

In the totally implantable artificial heart system now being developed by the authors, seven lithium-ion secondary batteries connected in series are used as the backup secondary battery. In this paper are reported the results of investigations made on the charging and discharging characteristics of four kinds of lithium-ion secondary batteries using different cathode active materials and electrolytes. It is found that, of the four kinds of batteries under examination, one that uses LiNi/sub 0.8/Co/sub 0.2/O/sub 2/ as cathode active material and electrolyte B is most suitable, because with this battery the charging time is shortest and the temperature rise at the time of discharging is least. When these lithium-ion secondary batteries are used to drive a totally implantable electrohydraulic artificial heart, it is found that the system is capable of continuous operation for about an hour with a pump output flow of 7.6 L/min and a power consumption of 17.8 W.