Constructing Garnet Electrolytes with Internal 3‐D Electronic Insulation Network for Dendrite‐Free Solid‐State Lithium Metal Batteries

Abstract Garnet‐type solid‐state lithium metal batteries (SSLMBs), with high energy density and superior safety performance, have been recognized as one of the most promising next‐generation energy storage technologies. However, the severe lithium dendrite penetration issue of garnet‐type electrolytes significantly impedes the practical application of SSLMBs. Herein, garnet‐type electrolyte Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO) with high dendrite‐suppressing ability is fabricated by constructing a 3‐D continuous electronic insulation network at the grain boundaries of LLZTO with glass electrolyte 50Li₂O‐38B₂O₃‐12SiO₂ (LBS). The selected LBS, with low melting temperature, moderate lithium‐ion conductivity, and extremely low electronic conductivity (≈1.7 × 10⁻¹⁰ S cm⁻¹), significantly facilitates the densification of LLZTO and by existing at the grain boundaries in the form of amorphous glass, impedes the transport of electrons within the electrolytes and ultimately prevents the growth of lithium dendrite during battery cycling. As a result, the fabricated Li|LLZTO‐LBS|Li symmetric cells show a high critical current density of 1.1 mA cm⁻² and a stable lithium plating/stripping performance for over 1000 h at 0.2 mA cm⁻². Moreover, the constructed Li|LLZTO‐LBS|LiFePO₄ full cells deliver a high initial specific capacity of 141.8 mA h g⁻¹ at 1.0C and can be cycled stably for over 100 cycles at 0.2C.