In Situ Li-In Anode Formation on the Li₇La₃Zr₂O₁₂ Solid Electrolyte in All-Solid-State Battery

Li7La3Zr2O12 is considered to be a promising solid electrolyte for all-solid-state batteries. The problem of the poor wettability of Li7La3Zr2O12 by metallic Li can be solved by using Li-In alloys as anode materials. Li-In alloys with different Li contents (40–90 at%) were prepared by an in situ method and investigated in symmetric cells with a Li7La3Zr2O12-based solid electrolyte. The interface resistance between the Li-In alloy (90 at% Li) and solid electrolyte is equal to ~11 Ω cm2 at 200 °C. The cells with 80–90 at% Li in the Li-In anode show stable behavior during cycling with an applied current of ±8 mA (40 mA cm−2). No degradation of the Li7La3Zr2O12-based solid electrolyte in contact with the lithium–indium alloy was observed after galvanostatic cycling. Therefore, the Li-In alloy obtained by our in situ method can be applied as an anode material with Li7La3Zr2O12-based solid electrolyte in lithium power sources

Features of forming a low-temperature cubic Li7La3Zr2O12 film by tape casting

Currently, interest to lithium and lithium-ion all-solid-state power sources is rapidly growing all over the world. However, several issues should be addressed before all-solid-state batteries production: high resistance values of the solid electrolyte membrane and poor contact between electrolyte and electrode materials. The transition to thin-film technologies is one of the promising ways to solve these problems. Tape casting can be proposed to obtain thin-film solid electrolytes. In this research, the features of the structure formation, morphology and lithium-ion conductivity of Li7La3Zr2O12 films were investigated. Li7La3Zr2O12 films with the thickness of 35 µm were obtained by tape casting on Ni substrate. The influence of organic components’ content on homogeneous coatings formation was established. Heat treatment conditions for dried films were chosen based on differential scanning calorimetry and optical dilatometry. Phase change from tetragonal to low-temperature cubic modification occurs after annealing the Li7La3Zr2O12 films at 700 °C and higher. The annealed Li7La3Zr2O12 films have developed surface, which can lead to improved contact between the solid electrolyte and an electrode in an electrochemical cell. Li7La3Zr2O12 films annealed at 800 °C have the highest lithium-ion conductivity values (2.5·10–7 and 1.5·10–5 S·cm–1 at 90 and 215 °С, respectively). The technology of Li7La3Zr2O12 films formation with the thickness of ~23 µm by tape casting was developed