Conformation of lithium-aluminium alloy interphase-layer on lithium metal anode used for solid state batteries

The effects of an Li-Al layer on the modified-Li anode based on solid state batteries are studied. The structure, surface morphology, and cyclic stability of the modified-Li anode are examined by X-ray diffraction spectroscopy, scanning electron microscopy, and electrochemical tests. Results show that interphase layer can prevent Li from reacting with Li_1.5Al_0.5Ge_1.5(PO₄)₃ and displays a much better cycling stability compared with the bare-Li anode used in symmetric cells. The assembled solid state batteries with modified-Li anode and LiMn_0.8Fe_0.2PO₄ cathode can deliver an initial discharge capacity of 153 mAh g⁻¹ with good cyclic stability and rate performance at 50 °C. The reason for this is that the Li-Al alloy interphase layer can prevent localised Li enrichment, then suppress lithium dendrite growth, and the Li-Al layer on the anode possesses good stability in the presence of Li_1.5Al_0.5Ge_1.5(PO₄)₃ powder and better interphase contact results between the anode and solid electrolyte in solid state batteries.