Elastic Properties, Defect Thermodynamics, Electrochemical Window, Phase Stability, and Li⁺ Mobility of Li₃PS₄: Insights from First-Principles Calculations

Abstract

The improved ionic conductivity (1.64 × 10(-4) S cm(-1) at room temperature) and excellent electrochemical stability of nanoporous β-Li3PS4 make it one of the promising candidates for rechargeable all-solid-state lithium-ion battery electrolytes. Here, elastic properties, defect thermodynamics, phase diagram, and Li(+) migration mechanism of Li3PS4 (both γ and β phases) are examined via the first-principles calculations. Results indicate that both γ- and β-Li3PS4 phases are ductile while γ-Li3PS4 is harder under volume change and shear stress than β-Li3PS4. The electrochemical window of Li3PS4 ranges from 0.6 to 3.7 V, and thus the experimentally excellent stability (>5 V) is proposed due to the passivation phenomenon. The dominant diffusion carrier type in Li3PS4 is identified over its electrochemical window. In γ-Li3PS4 the direct-hopping of Lii(+) along the [001] is energetically more favorable than other diffusion processes, whereas in β-Li3PS4 the knock-off diffusion of Lii(+) along the [010] has the lowest migration barrier. The ionic conductivity is evaluated from the concentration and the mobility calculations using the Nernst-Einstein relationship and compared with the available experimental results. According to our calculated results, the Li(+) prefers to transport along the [010] direction. It is suggested that the enhanced ionic conductivity in nanostructured β-Li3PS4 is due to the larger possibility of contiguous (010) planes provided by larger nanoporous β-Li3PS4 particles. By a series of motivated and closely linked calculations, we try to provide a portable method, by which researchers could gain insights into the physicochemical properties of solid electrolyte.

Correlated Migration Invokes Higher Na+‐Ion Conductivity in NaSICON‐Type Solid Electrolytes

“…Our previous work [43,44] and that of some others [45][46][47] verified that correlated jumps lead to lower energy barriers and higher ion conductivity in some fast ion conductors, for example, Li 3 OX (X = Cl, Br), [45] doped Li 3 PO 4 , [46] and Li 7 La 3 Zr 2 O 12 (LLZO). Our previous work [43,44] and that of some others [45][46][47] verified that correlated jumps lead to lower energy barriers and higher ion conductivity in some fast ion conductors, for example, Li 3 OX (X = Cl, Br), [45] doped Li 3 PO 4 , [46] and Li 7 La 3 Zr 2 O 12 (LLZO).…”

Theoretical study of superionic phase transition in Li2S

“…In addition, different strategies have been proposed to increase carrier concentration and mobility (i.e. improving Li ion conductivity) in solid state materials 2, 5, 6 . Moreover, superionic compounds are widely investigated because of their fundamental interests and potential applications in solid-state batteries, fuel cells, and gas sensors 7–12 .…”

Simulation of the Effect of Contact Area Loss in All-Solid-State Li-Ion Batteries

“…As the first step, contact area was introduced into a 1-dimensional (1-D) Newman model to simulate the discharge process of an all-solid-state Li-ion battery, which is composed of a metallic Li anode, LiCoO 2 positive electrode, and a LiPON-like solid electrolyte. Since Li metal has low hardness and exhibits creep behavior at room temperature, [36][37][38] it is more likely to maintain a good contact with the solid-electrolyte due to plastic deformation. This is consistent with the reported much higher exchange current density for the metallic Li electrode 39 than that for LiCoO 2 in all-solid-state Li-ion batteries.…”