关键词: 石榴石型固体电解质, 电极/固态电解质界面, 铝锂合金

Abstract:

Garnet-type solid electrolyte is a newly developed Li ion conductor and promising in the application of all-solid-state batteries. However, Garnet is incompatible with Li anode, which restricts the application of Garnet-type solid batteries. In order to improve the contact between Garnet-type solid electrolyte and Li electrode, a composite anode which contains Al-Li alloy (Al₄Li₉) was prepared as an electrode. Al-Li alloy has many advantages such as easy preparation, low cost, simple post-treatment and high capacity. Garnet-type Li_6.5La₃Zr_1.75W_0.25O₁₂ (LLZWO) was synthesized via solid-state reaction. Garnet solid electrolyte has poor interfacial wettability with lithium, but has good interfacial wettability with Al-Li alloy. By using Al-Li alloy as an electrode, the contact between LLZWO and Li electrodes could be well improved. SEM images also confirmed that Al-Li alloy and Garnet had a sufficient interface contact. On the other side, the interface resistance could be dramatically reduced. Impedance spectra show that the interface resistance between Al-Li alloy and Garnet reduced from 740.6 Ω·cm ² to 75.0 Ω·cm ², which is only one-tenth of interface resistance between Li alloy and Garnet. Symmetric cell with Al-Li alloy and Garnet showed excellent and stable cycle performance with almost 0 polarization voltage when cycling at a current density between 50 μA·cm ^-2 and 100 μA·cm ^-2. At a current density of 50 μA·cm ^-2, the cell cycled 400 hours stably without formation of lithium dendrite.

Key words: Garnet-type solid electrolyte, electrode/solid electrolyte interface, Al-Li alloy