In-situ construction of a composite interlayer for dendrite-free Li6.75La3Zr1.75Ta0.25O12 solid-state batteries

Garnet -type solid electrolytes have been indubitably regarded as one of the most promising solid electrolytes due to their excellent stability and high safety against Limetal. However, the poor interfacial wettability and high interfacial impedance between garnet and Li metal may lead to the formation of Li dendrites and the deterioration of electrochemical performance. In this work, a lithiophilic urea coating is prepared on the surface of solid ceramic electrolyte Li6.75La3Zr1.75Ta0.25O12 by drop -casting. The lithium -nitrogen (Li-N) interlayer is formed by the chemical reaction of molten lithium with urea. This interface layer improves interfacial contact and inhibits the growth of lithium dendrites. Consequently, the interfacial resistance of symmetrical cell with ureaLi6.75La3Zr1.75Ta0.25O12 reduces to 85 omega cm2 and the critical current density (CCD) reaches 1.70 mA cm -2. Full batteries assembled using LiFePO4 as the cathode also have a good cycling performance. The results demonstrate the viability of the proposed strategy and offer a promising solution to the interface issue between Li metal and solid electrolytes.