Hollow porous polyhedral Co3O4 as functional fillers for all-solid-state PEO-based lithium metal batteries

Enhancing ionic conductivity and Li dendrite inhibition capability in poly(ethylene oxide) (PEO)-based solid polymer electrolytes (SPEs) is imperative for the advancement of all-solid-state lithium metal batteries (ASSLMBs). Herein, we incorporate the inorganic functional nanofiller of hollow porous polyhedral Co 3 O 4 to facilitate the formation of amorphous regions, thereby enhancing the migration of PEO chain segments. The suitable hollow porous polyhedral structure offers the advantage of minimizing filler agglomeration and providing a continuous and extensive network for ion transport, thereby enhancing ionic conductivity. The addition of 7 wt% Co 3 O 4 to PEO SPEs (PEO+ Co 3 O 4 –7) results in an enhanced ionic conductivity of 2.68 × 10 −3  S cm −1 and the Li + transference number of 0.493 at 60 °C. Furthermore, Li//Li symmetric cell with PEO+ Co 3 O 4 –7 SPEs enables a stable cycle for 1000 h at 0.2 mA cm −2 . LiFePO 4 / PEO+ Co 3 O 4 –7/Li cell indicates an initial capacity of 149 mA h g −1 and a reversible capacity of 113 mA h g −1 after 200 cycles at 0.2C. This study emphasizes the importance of constructing efficient ion transport paths through structural design.