Interface features between 30Li2O·47.5V2O5·22.5B2O3 glassy cathode and Li7La3Zr2O12 solid electrolyte

Abstract

Glassy cathode deposition on solid electrolyte substrate applied to lithium middle-temperature all-solid-state batteries was investigated. The 30Li2O·47.5V2O5·22.5B2O3 (LBV) glassy cathode is crystallized on Li7La3Zr2O12 (LLZ) solid electrolyte substrate at various temperatures (650–850 °C) and holding times (0.5–5 min). The phase composition of the crystallized glass and vanadium oxidation state are determined by the XRD and XPS analysis. The different lithium vanadates form at all studied temperatures, and the boron-containing phases appear at temperatures greater than 750 °C. SEM investigation shows that the lithium borate-vanadate glass crystallized at 750 °C to create the optimal interface and close contact between the electrode and the electrolyte. Processing at lower temperatures does not allow for good contact, and processing at higher temperatures leads to the interaction between the cathode material and ceramic electrolyte. The optimal mode of 30Li2O·47.5V2O5·22.5B2O3 glassy cathode deposition on the substrate is found to be glass powder annealing for 0.5 min at 750 °C. This LBV|LLZ cell has the highest conductivity and the lowest polarization resistance on the cathode|electrolyte interface. The universality of this deposition mode is demonstrated using Li3.65Al0.05Ge0.95P0.2O4 ceramic substrate as an example. Thus, the LBV glass can be used for the formation of an optimal interface with other lithium-ion solid electrolytes.