A porous garnet Li7La3Zr2O12 scaffold with interfacial modification for enhancing ionic conductivity in PEO-based composite electrolyte

The composite combined Li7La3Zr2O12 (LLZO) and PEO is viewed as a promising solid-state electrolyte for lithium-ion batteries due to its chemical stability, wide electrochemical window, mechanical flexibility and easy fabrication procedure. However, the primary challenges of low ionic conductivity and poor interfacial compatibility remain unresolved. Herein, a co-modified composite solid-state electrolyte based on the porous Al-doped LLZO (Al-LLZO) garnet scaffold cooperated with Ca-coordinated Dynasylan IMEO (Triethoxy-3-(2-imidazolin-1-yl) propylsilane, named DI) and PEO (denoted as CSE-DI-Ca) is reported. Benefiting from the fast lithium ion conduction in porous Al-LLZO network and interfacial strengthening modification between ceramics and polymer, CSE-DI-Ca exhibits a high ionic conductivity of 6.38✕10−4 S cm−1 at room temperature. The unique ceramic structure of CSE-DI-Ca also leads to an enlarged electrochemical window of 6 V vs. Li+/Li, good thermal stability under 360 °C, and an improved mechanical strength of 8.91 MPa to block lithium dendrites. Furthermore, as an evidence of the compatibility with high-voltage battery, the LiNi0.6Co0.2Mn0.2O2(NCM622)|CSE-DI-Ca|Li coin cell delivers an initial discharge capacity of 130.2 mAh g−1 at 0.1 C at room temperature and maintains a capacity of 127.3 mAh g−1 after 120 cycles. All these superior properties indicate that the as-prepared composite holds great promise as an effective solid-state electrolyte to be used in next-generation lithium-ion batteries.