Fabrication of asymmetric bilayer solid-state electrolyte with boosted ion transport enabled by charge-rich space charge layer for ‐20~70°C lithium metal battery

Li6.4La3Zr1.4Ta0.6O12 (LLZTO), a typical oxidizing ceramic solid electrolyte of excellent lithium-ion conductivity, is considered as a promising candidate for next-generation high-energy-density solid-state lithium metal batteries (SSLMBs). However, great challenges, such as the unexpected growth of lithium dendrites and the excessive resistance of electrolyte/electrode interface, need to be well addressed through their commercialization. Here, a local conjugated polymer solid-state electrolytes nanolayer was formed onto ceramic oxide particles via selective adsorption through an in-situ polymerization process. Li solid NMR spectra and TEM (ex-situ and in-situ) characterizations suggest that optimized layer provided effective pathways for Li+ conduction between SSEs and ceramic oxide. Consequently, this composite electrolyte possesses a high ionic conductivity of 0.69 mS cm−1 at 25 °C. Lithium symmetrical batteries exhibit a reduced charge voltage polarization and the critical current density could be increased up to 2.4 mA cm−2. Moreover, lithium metal batteries based on CPE show an excellent cycle stability over a broad temperature range from −20 to 70 °C, and super-long cycling performance (> 600 cycles) at 0.5 C under 0 °C. This new strategy creates a new route to resolve the LLZTO/electrode interface issue by constructing rich-large space charge layer and promoting Li+ conduction, it will be helpful for the commercialization and application of wide-temperatures SSLMBs.