batteries for electric vehicles with metallic Li as an anode. However, the stability between solid-state
electrolytes and metallic Li is not well understood. Lithium phosphorous sulfides are a promising class of
solid-electrolytes owing to their high ionic conductivity (10-4 – 10-3 S cm-1 at 25 °C), low interface
resistance against metallic lithium, and can be consolidated to > 90 % relative density at room
temperature1 . In this work, the chemical, electrochemical, and mechanical stability of hot-pressed 75Li2S-
25P2S5 (mol %), or LPS, between 200 and 550 °C was investigated. Hot pressing produced high relative
density and crystalline LPS pellets that were characterized using multiple electrochemical techniques. AC
impedance measurements were used to characterize the stability of the Li-LPS interface. The
electrochemical performance of LPS was analyzed as a function of current density between 0.01 and 1.0
mA cm-2 followed by cross-sectional microstructural analysis. It will be shown that: i) below or equal to
0.05mA cm-2 ohmic behavior is observed, ii) at 0.1mA cm-2 a transition behavior occurs identified by an
instability in polarization, and iii) above or equal to 0.5mA cm-2 , the potential decreases and is believed to
be related to the formation of an electronically conducting phase. Acoustic impulse excitation
measurements were used to determine changes in the elastic constants after DC cycling of Li-LPS.
Additionally, materials characterization such as Raman, XRD, and SEM will be presented to correlate the
densification conditions with DC cycling stability. We believe this is one of the first studies to
characterize the chemical, electrochemical, and mechanical stability of a Li-LPS interface. The
methodology established in this work could be applied to other solid-state electrolytes as well.
Reference
- Sakuda, Atsushi, Akitoshi Hayashi, and Masahiro Tatsumisago. "Sulfide solid electrolyte with favorable mechanical property for all-solid-state lithium battery."Scientific reports 3 (2013)