Borosilicate Glass-Enabled Antifracture NASICON Solid Electrolytes for Lithium-Metal Batteries

Low-cost sodium superionic conductor (NASICON) solid electrolytes featuring high ionic conductivity and high safety characteristics are regarded as one of the best choices to replace liquid electrolytes in energy-intensive lithium (Li)-metal batteries. However, the conventional NASICON electrolytes prepared by pressureless sintering generally exhibit low density and poor fracture toughness, largely limiting their wide practical application. In this work, borosilicate glass (BG) as the second phase was added to Li1.4Al0.4Ti1.6(PO4)3 (LATP) during the sintering process and a strong and tough ceramic electrolyte. The results showed that after BG was added, the fracture strength of the obtained ceramic electrolytes reached 74 MPa, which was 2.38 times that of pure LATP. The activation energy showed a reduction of 14.3% to 0.3 eV compared with pure LATP, and the relative density reached 97.17%, attaining a high level under pressureless sintering conditions. In addition, the all-solid-state batteries with LiFePO4 (LFP) as the cathode and Li metal as the anode exhibited good cycling stability after surface modification and a discharge specific capacity of 154.5 mA·h·g–1 at 25 °C and 0.1 C. After 100 cycles, the Coulombic efficiency was close to 100%. This method provides a feasible avenue for preparing ceramic electrolytes with high mechanical strength and high ionic conductivity.