Restraining lithium dendrite formation in all-solid-state Li-metal batteries via the surface modification of the ceramic filler

Polymer-based all-solid-state Li-metal batteries (ASSLMBs) have acquired considerable attention owing to their applicability to various systems and their enhanced safety characteristics. Hence, ASSLMBs can potentially replace flammable organic-liquid-electrolyte-based Li-ion batteries. However, owing to the interfacial instability and Li dendrite formation, ASSLMBs exhibit low capacity deprivation. To overcome this limitation, in this study, the hydrophilic nature of SSZ-13 zeolite was altered to hydrophobic using OH-functional silicone-modified polyacrylate (BYK-SILCLEAN 3700). A hydrophobic surface-modified zeolite filler (SSZ-13, MZLT) was incorporated into a polyethylene oxide (PEO) matrix, which permitted considerable Li salt adsorption and ensured the uniform distribution of MZLT in the PEO matrix. This resulted in a substantially improved ionic conductivity (σ) of the electrolyte, thereby enhancing the performance and durability of ASSLMBs. Furthermore, excellent σ (3.46 × 10⁻² S cm⁻¹ at 60 °C) was achieved through the surface modification of the filler, resulting in a Li transference number of 0.83. The Li plating–stripping results (for 1800 h of cycling at a discharge current of 100 μA cm⁻²) suggested satisfactory compatibility of the electrolyte with the Li metal. Scanning electron microscopy and X-ray photoelectron spectroscopy results confirmed that the growth of Li dendrites was significantly suppressed, leading to a retention rate of 98.5% after 200 cycles. Additionally, the fire retardancy was considerably improved. The findings of this study highlight the potential of composite-electrolyte-based ASSLMBs as candidates for energy storage devices.