Embodiments of the invention are related to biosorbable batteries, amongst other things. In an embodiment, the invention includes a biosorbable battery assembly including an anode, a cathode, and a biosorbable separation element. The anode can include an anode material, wherein electrochemical oxidation of the anode material results in the formation of reaction products that are substantially non-toxic. The cathode can include a cathode material, wherein electrochemical reduction of the cathode material results in the formation of reaction products that are substantially non-toxic, the cathode material having a larger standard reduction potential than the material of the anode. The biosorbable separation element can be disposed between the anode and the cathode and can be configured to provide electrical insulation between the anode and the cathode. In an embodiment, the invention includes a medical device system including an implanted medical device and a biosorbable battery in electrical communication with the implanted medical device. Other embodiments are also included herein.