Deformable lithium-ion batteries for wearable and implantable electronics

Deformable lithium-ion batteries (LIBs) have attracted increasingly widespread attention due to their enormous prospects for powering flexible electronics. In recent years, technological advances in manufacturing deformable LIBs at the material and device levels have promoted the rapid and sustainable development in energy storage. Despite recent advances, there is so far no review to make a comprehensive introduction focusing on the topic of deformable LIBs for future wearable and implantable electronics. This review systematically summarizes the recent progresses in deformable LIBs and their applications in various scenarios. Specifically, we classify the deformable LIBs into several categories such as stretchable LIBs, self-healing LIBs, shape memory LIBs, biodegradable LIBs, etc. Initially, the fundamentals of LIBs, such as their components and working mechanism, are introduced. Then, various strategies for constructing deformable LIBs are discussed in detail, with a particular focus on stretchable LIBs. Subsequently, the latest advances in the application of deformable LIBs in wearable/implantable electronic systems are summarized. To finalize, the challenges and prospects are outlined to promote further development in this booming field. This review has the potential to inspire researchers working on the development of high-performance deformable energy storage devices and to contribute to the future development of flexible electronics.