Ultrathin Composite Li Electrode for High‐Performance Li Metal Batteries: A Review from Synthetic Chemistry

Abstract Li metal anode attracts tremendous attention in next‐generation battery systems with high energy density, but volume change and dendritic growth limit its practical applications. Composite Li electrode can fundamentally suppress the volume effect and decrease the local current density, ensuring long‐term cycling life. However, up to now, there is only limited success in preparing multifarious composite Li electrode, especially in thickness, posing great obstacles to further promoting its research and application. In this review, the thickness of composite Li electrode are strategically focussed upon and the merits and existing challenges of ultrathin composite Li electrode are evaluated. Meanwhile, the design principles and fundamental requirements for ultrathin composite Li electrode in the future are summarized and the existing cases related to this field are outlined as much as possible from synthetic chemistry, hoping it can serve as a handbook to provide a comprehensive understanding and guide reliable fabrication of advanced composite Li electrode. Challenges and opportunities regarding this burgeoning field are also critically evaluated at the end of this review.