Building a Better Li-Garnet Solid Electrolyte/Metallic Li Interface with Antimony

The deployment of Li-garnet Li7La3Zr2O12 (LLZO) solid-state electrolytes in solid-state batteries is severely hampered by their poor wettability with metallic Li. In this work, Sb is presented as a compelling interfacial layer allowing superior wetting of Li onto a LLZO surface, resulting in a remarkably low Li/LLZO interfacial resistance of 4.1(1) omega cm(2). An atomistic insight into Sb-coated LLZO interface using soft and hard X-ray photoelectron spectroscopy and focused ion beam time-of-flight secondary ion mass spectrometry shows the formation of a Li-Sb alloy as an interlayer. It is determined that the Li/Sb-coated LLZO/Li symmetrical cells exhibit a high critical current density of up to 0.64 mA cm(-2) and low overpotentials of 40-50 mV at a current density of 0.2 mA cm(-2) without applying external pressure. The electrochemical performance of Sb coated-LLZO pellets is also assessed with an intercalation-type V2O5 cathode. Li/Sb-coated-LLZO/V2O5 full cells deliver stable capacities of around 0.45 mAh cm(-2), with a peak current density of 0.3 mA cm(-2).

Automated summary

The study finds that using Sb as an interface layer helps to improve the wettability of Li on LLZO, reducing the interfacial resistance. Experimental results show that both Li/Sb-coated LLZO/Li cells and LLZO/V2O5 full cells exhibit good electrochemical performance without external pressure.