Medium and high discharge rate combination battery and method

An electrochemical battery comprises: (a) a casing; (b) a first electrochemical cell house within the casing and comprising: (i) a first anode comprising an alkali metal electrically associated with a first anode current collector; (ii) a means for connecting the first anode current collector to an external lead; (iii) a first cathode of cathode-active material electrically associated with a first cathode current collector; (iv) a means for connecting the first cathode current collector to an external lead; and (v) an electrolyte between the first anode and cathode; and (c) a second electrochemical cell housed within the casing and comprising the same 5 components as the first cell. Also claimed are: (1) an electrochemical battery as above, in which the first cell is dischargeable independently of the second cell to provide separate and independent sources of electrical energy; (2) in a combination with an implantable medical device requiring electrical power for a monitoring function and a device-operating function, a battery comprising: (a) a medium-rate constant discharge or constant drain cell for providing low-level currents for the monitoring function; (b) a high-rate pulse discharge cell for providing high-level current for the operating function; and (c) a single case contg. both cells; and (3) a method of providing an electrochemical battery capable of simultaneous and independent discharge at both a constant discharge rate and under a current-pulse discharge application.