Electrolyte based on laser-generated nano-garnet in poly(ethylene oxide) for solid-state lithium metal batteries

Incorporating ceramic superionic fillers in Li⁺ conductive polymer matrix is an efficient strategy for developing solid-state electrolytes, while challenges remain on embedding ceramic fillers with well-defined size and well-dispersion that could maximize the interfacial interactions and decrease the crystallization of polymer for improved conductivity. Herein we report an intriguing strategy of liquid-phase laser manufacturing to in-situ generate nano Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (Nano-LLZTO) with the average size of 8.3 nm in the presence of PEG. Even dispersion of Nano-LLZTO in poly(ethylene oxide) (PEO) matrix is realized benefiting from the interfacial comparability between PEO and PEG. Such embedding leads to maximally an order of magnitude enhancement of Li⁺ conductivity by incorporating Nano-LLZTO with the content of 2.0 wt%, compared to that of PEO-based electrolyte. Meanwhile, enhanced dendrite-suppression capability and interfacial stability are achieved with a stable and low overpotential of ∼ 108 mV and a long lifespan up to 400 h in symmetric cells, and enhanced tensile strength close to 3.0 MPa and the maximum strain of 2200% are simultaneously achieved. Solid-state batteries comprising of PEO-based electrolyte embedded with Nano-LLZTO demonstrates stable cycling performances over 850 cycles. Thus, the proposed facile design of embedding nano garnet is anticipated to provide an efficient alternative to address the weak Li⁺ conductivity of polymer matrix for high-performance solid-state electrolytes.