Mixed Ion and Electron-Conducting Scaffolds for High-Rate Lithium Metal Anodes

Li metal batteries are considered a promising candidate for next-generation rechargeable batteries. However, the practical application of Li metal batteries has been hindered by many challenges, especially the cycling stability of Li anodes due to their uncontrollable dendrite growth, volume fluctuation, and side reactions. These problems are more severe under high-rate charge/discharge process. Therefore, the realization of stable cycling of Li anodes under high current density is crucial for the practical application of Li metal batteries. In this Progress Report, the authors focus on the stability of metallic Li through interphase design or microstructure construction. The advantages and drawbacks of the first-generation 3D scaffolds are summarized, and a review of recent research progress in this area is generated. As high-rate cycling of metallic Li is a complex dynamic problem, a scaffold with high mixed ionic and electronic conductivity may be a promising approach. The different design strategies of mixed ion and electron-conductive scaffolds working with liquid and solid electrolytes are discussed, along with their technical challenges. Further directions of mixed ion and electron-conductive scaffolds are also proposed.