There are two main types of defibrillators available, one is the Implantable Defibrillator and the second is the Automated External Defibrillator (AED). Both devices are designed to be portable and their operation to be critical; the devices must function at all times meaning that their power source must be both portable and reliable to meet such demands.

An Implantable Defibrillator is a small device, about the size of a pager (however, as technology advances these devices are getting smaller) that monitors a persons heart rate. It is implanted underneath the skin of a person's chest near the collarbone with wires that run to the heart. The device runs using batteries to monitor the heart rate, send electric signals to a heart that is beating to slow, and deliver an electric shock to help restore a normal heartbeat to a heart that's beating chaotically and much too fast.

Under normal operation these devices pull a constant low current, however when the device has to deliver an electric shock, the drain current will increase dramatically for the period of the shock. Because of this the battery used to power this device must be able to deliver a constant current drain as well as being able to cope with large current pulses; they also must have a long service life. The Sonnenschein and Tadiran Lithium PulsesPlus range are ideal for applications requiring long life and high energy under high pulse requirements.

An AED Defibrillator is a portable version of the Implantable Defibrillator which can audibly prompt and deliver an electric shock that will disrupt or stop the heart's dysrhytmic electrical activity. As with the Implantable Defibrillator, the AED is required to deliver high current pulses for short periods, however unlike the Implantable type, the AED's are not working around the clock. They could be lying idle for extended periods before being called into action to deliver shocks to a patient and monitor their state without fail. This specification is similar to that of the Implantable Defibrillators however another factor is that of a long-shelf life and the ability to deliver high current pulses after periods of being idle. The Sonnenschein and Tadiran Lithium PulsePlus range again offers the solution to this application. As well as high stable voltage, high pulse current capability, they have a long shelf life (up to 10 years) and suffer no passivation effects meaning that the cells will deliver power instantly even after extended storage periods.