3D frameworks in composite polymer Electrolytes: Synthesis, Mechanisms, and applications

Solid-state lithium metal batteries (LMBs) show promising prospects due to the high energy density and high safety. Developing novel solid electrolytes with high performance is of great significance for practical application of LMBs. Among all kinds of solid electrolytes, composite polymer electrolytes (CPEs) consisting of inorganic fillers and polymer electrolytes have drawn increasing focus because of their improved ionic conductivity and mechanical strength. However, the incompatibility between the inorganic fillers and organic polymer matrix leads to randomly distributed fillers, inevitably causing discontinuous ion transport and insufficient mechanical strength. Besides, the heavy fillers tend to aggregate and precipitate in the polymer matrix, leading to monolithic blocks for continuous ion transport. Herein, introducing ion-conducting 3D frameworks into polymer electrolytes is an effective strategy to provide continuous ion transport and mechanical support. The advances of 3D frameworks for CPEs are summarized in this review. For example, the structural design and synthesis methods of 3D frameworks and the mechanisms of ionic conductivity improvement are discussed in detail. Furthermore, some important works of the 3D frameworks in CPEs for solid-state LMBs are presented. Finally, the challenges and directions of high-performance CPEs in future research are prospected.