Implantable medical devices such as leadless cardiac pacemakers may include a rechargeable battery, and a receiving antenna for receiving radiative energy from an external transmitter. Energy captured by the receiving antenna of the implantable medical device may be converted into electrical energy that may be used to recharge the rechargeable battery of the implantable medical device. Since the rechargeable battery does not have to initially store sufficient energy to power the implantable medical device over its entire useful life, the battery itself and thus the implanted medical device can be made smaller while still achieving device longevity expectations.