Implantable Batteries for Bioelectronics

Conspectus Implantable bioelectronics that interface directly with biological tissues have been widely used to alleviate symptoms of chronic diseases, restore lost or degraded body functions, and monitor health conditions in real-time. These devices have revolutionized medicine by providing continuous therapeutic interventions and diagnostics. Energy sources are the most critical components in implantable bioelectronics, as they determine operational lifetime and reliability. Compared with other energy storage and harvesting devices and wireless charging methods, batteries provide high energy density and stable power output, making them the preferred choice for many implantable applications. The advent of implantable bioelectronic devices has been significantly propelled by the high energy densities offered by lithium battery technology, which has led to a profound transformation in our daily lives. To advance the field of implantable bioelectronics, the development of next-generation implantable batteries is essential. These batteries must be soft to match the mechanical properties of biological tissues, minimizing tissue damage and immune responses. Additionally, they must be biocompatible, particularly when in proximity to vital organs like the heart and brain, to prevent toxicity and adverse reactions. Beyond biocompatibility, these batteries need to exhibit excellent electrochemical performance, thermomechanical resilience, and structural integrity for reliable operation in body fluids over extended periods. Enhancing the energy and power density of these batteries can lead to device miniaturization, extend their service life, improve operating efficiency, and meet a broader range of high-power applications. Achieving these advancements not only enables cableless and shape-conformal integration with multifunctionality but also underscores the significant research efforts dedicated to understanding and optimizing the performance of next-generation implantable batteries. To this end, numerous research efforts have been devoted in recent years to developing next-generation implantable batteries from material development, structural design, and performance optimization perspectives. In this Account, we first outline the development history of current implantable batteries from their inception to the present day. We then delineate the requirements for the next generation of implantable batteries, considering emerging application scenarios. Subsequently, we review the recent advancements in the development of soft, biocompatible, long-term stable, high-energy, and high-power-density implantable batteries. Additionally, we explore the efficient integration of these batteries into biomedical devices. We conclude with the development routes and future perspectives for implantable batteries. This Account promotes the development of new implantable batteries through the collaboration of multiple disciplines, including energy, materials, chemistry, biomedical science, and engineering. The emergence of advanced implantable battery technologies is expected to offer countless opportunities to enhance bioelectronics. These advancements will alter the current paradigm of medicine and pave the way for a revolutionary era of human-machine interaction.