A solid composite electrolyte based on three-dimensional structured zeolite networks for high-performance solid-state lithium metal batteries

Solid polymer electrolytes (SPEs) are regarded as promising candidates for next-generation solid-state lithium metal batteries (SSLMBs) due to their high flexibility and excellent processability, whereas their practical application remains a challenge to simultaneously achieve high ionic conductivity, superior inherent stability, and desirable interfacial compatibility with the Li metal anode. Here, we report a composite solid electrolyte (CSE) incorporating a three-dimensional zeolite network (3D Zeo) into a poly(ethylene oxide) (PEO) matrix containing lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt (3D Zeo/PEO). The interconnected 3D Zeo provides continuous Li⁺-conduction pathways and promotes the amorphization of the polymer and the dissociation of the Li salt <i>via</i> Lewis acid-base interactions. The resulting 3D Zeo/PEO CSE exhibits an ionic conductivity of 1.62 × 10^-4 S cm^-1 at room temperature and an electrochemical stability window up to 5.7 V <i>vs.</i> Li⁺/Li, significantly surpassing those of LiTFSI-PEO SPE (3.23 × 10^-6 S cm^-1, 4.9 V). Leveraging the regulatory effect of the 3D Zeo/PEO CSE on Li⁺ deposition and solid electrolyte interphase formation, the symmetric cell demonstrates stable cycling over 2300 h with an overpotential of 0.13 V, and the full cells also deliver superior high-rate capability and long-term stability with a capacity retention of 92% after 500 cycles at room temperature, far exceeding the performance of batteries using LiTFSI-PEO SPE and CSE with zeolite-based particle fillers. This work provides a promising approach for the design of CSEs to achieve high interfacial compatibility and uniform Li⁺ deposition for next-generation SSLMBs.