FIELD

The present disclosure relates to electrochemical devices. In particular, the present disclosure relates to batteries.

BACKGROUND

Electrochemical cells or batteries are used as the power source in many applications, including implantable medical devices.FIG. 1Aschematically illustrates an exemplary design for a battery100known in the art. Battery100includes a cathode102, an anode104separated from the cathode via a separator106, and some form of electrolyte108in contact with anode104and cathode102. The current from battery100is typically delivered to a load110, such as an implantable medical device. The size of load110affects the amount of current that flows between anode104and cathode102.

Many medical device electrochemical cells are designed for high current pulse discharge and low or no voltage delay. This design requirement is particularly important in an implantable cardioverter defibrillator (ICD), also referred to as an implantable defibrillator, since an ICD must deliver high voltage shocks to the heart immediately after the detection of arrhythmia. It is desirable for these cells to have a high energy density to allow for the small size of implantable medical devices. An end-of-life (EOL) indicator for the battery may also be an important feature for this kind of application.

A silver vanadium oxide (SVO) cathode active material offers a high discharge rate capability and an EOL indicator because of its sloped discharge voltage curve. Another cathode active material, sub-fluorinated carbon fluoride (CFx, where x=˜1), offers a higher energy density, but it has a low discharge rate capability and no EOL indicator. These two cathode active materials have been combined in several types of cathode designs in an attempt to obtain the beneficial properties of each active material.

FIG. 1Billustrates a three-layer cathode110which can be utilized in place of the cathode102in battery100. In the three-layer cathode110, a sub-fluorinated carbon fluoride (CFx) layer112is disposed between two SVO layers114, with two current collectors116separating layer112from layers114. The three-layer design has a low packing efficiency due to the need for two current collectors. This design also increases manufacturing complexity.

FIG. 1Cillustrates a mixed cathode118which can be utilized in place of the cathode102in battery100. In mixed cathode118, sub-fluorinated carbon fluoride (CFx) and SVO are mixed together to form single layers120on a current collector122. This mixed cathode design simplifies the manufacturing process but has a lower discharge rate capability than a pure SVO cathode.

A cathode which provides a high energy density and a high discharge rate capability, and which acts as an EOL indicator for the battery presents a challenge which must be addressed.

BRIEF SUMMARY

Batteries having hybrid electrode configurations are disclosed herein.

One aspect of the present disclosure relates to a battery. The battery comprises an electrode assembly. The electrode assembly comprises a first cathode including a first cathode active material, a second cathode including a second cathode active material different from the first cathode active material, a first anode disposed between the first cathode and the second cathode, a first separator interposed between the first cathode and the first anode, and a second separator interposed between the second cathode and the first anode.

