Recent advances in implantable batteries: Development and challenge

Implantable medical devices (IMDs) play essential roles in healthcare. Implantable energy storage devices have been widely studied as critical components for energy supply. However, conventional batteries' shape, safety and properties restrict their application in these devices. Batteries with flexibility, biocompatibility, and biodegradability are conducive to matching the body tissue. In this paper, we summarize and classify implantable batteries into degradable and non-degradable batteries. Biodegradable batteries include Mg-based batteries, Znbased batteries, and sodium-ion batteries. Non-degradable batteries include certain Zn-based, lithium-based, biofuel, and other batteries. It focuses on summarizing the impact of variances in electrode materials, electrolytes, and preparation procedures on both the electrochemical performance and biodegradability of implantable batteries, which determine the application. Finally, future opportunities and challenges are discussed, which can contribute to IMDs implementation and the treatment of human diseases.