AbstractWe provide a critical review on the recent development of flexible lithium‐ion batteries (FLIBs) for flexible electronic devices. The innovative designs of cell configuration for bendable and stretchable FLIBs, selection of active materials, and evaluation methods for FLIBs are discussed. The grand challenges for FLIBs are energy density and scale‐up fabrication as demonstrated in the review. Furthermore, the lack of quantitative evaluation methods for FLIBs' performance and nondestructive tools to probe the mechanical degradation may significantly hinder the development of FLIB technologies. Perspectives for future research directions, based on the current state of progress, are discussed.image