Understanding the Effect of Interlayers at the Thiophosphate Solid Electrolyte/Lithium Interface for All-Solid-State Li Batteries

Abstract

All-solid-state Li-ion batteries afford possibilities to enhance battery safety while improving their energy and power densities. Current challenges for achieving high-performance all-solid-state batteries with long cycle life include shorting resulting predominantly from Li dendrite formation and infiltration through the solid electrolyte (SE) and increases in cell impedance induced by SE decomposition at the SE/electrode interface. In this work, we evaluate the electrochemical properties of two interlayer materials, Si and Li x Al (2−x/3) O 3 (LiAlO), at the Li 7 P 3 S 11 (LPS)/Li interface. Compared to the Li/LPS/Li symmetric cells in absence of interlayers, the presence of Si and LiAlO both significantly enhance the cycle number and total charge passing through the interface before failures resulting from cell shorting. In both cases, the noted improvements were accompanied by cell impedances that had increased substantially. The data reveal that both interlayers prevent the direct exposure of LPS to the metallic Li and therefore eliminate the intrinsic LPS decomposition that occurs at Li surfaces before electrochemical cycling. After cycling, a reduction of LPS to Li 2 S occurs at the interface when a Si interlayer is present; LiAlO, which functions to drop the potential between Li and LPS, suppresses LPS decomposition processes. The relative propensities toward SE decomposition follows from the electrochemical potentials at the interface, which are dictated by the identities of the interlayer materials. This work provides new insights into the phase dynamics associated with specific choices for SE/electrode interlayer materials and the requirements they impose for realizing high efficiency, long lasting all-solid-state batteries.

Sulfide‐Based Solid‐State Electrolytes: Synthesis, Stability, and Potential for All‐Solid‐State Batteries

“…The Li x Al (2− x /3) O 3 interlayer can drop the potential between Li 7 P 3 S 11 and Li and thus suppress the decomposition of Li 7 P 3 S 11 , while Si lithiates and maintains reducing potentials which facilitate the decomposition of Li 7 P 3 S 11 . This work proved that the interlayer material has an impact on the electrochemical potential at the Li/SSE interface, and therefore impact the chemical reactions occurring at the interface …”

Advanced Characterization Techniques for Interface in All‐Solid‐State Batteries

“…Phase variation of Li 7 P 3 S 11 /Au interface was also characterized by in situ Raman. [ 74 ] Li 4 P 2 S 6 was formed at ‐0.1 V and persisted over a wide range of potentials before converting back to PS 4 3− and P 2 S 7 4− at positive potentials and the PS 4 3− /P 2 S 7 4− to P 2 S 6 4− conversion on the interface was facilitated by Si buffer layer. Li et al further investigated the mechanism of the Se cathode in Se/Li 3 PS 4 /Li ASS‐LIBs by in situ Raman, confirming that lithiation for Se is complete and for PS 4‐ x Se x 3− is mild.…”

P4S10 modified lithium anode for enhanced performance of lithium–sulfur batteries

“…Accordingly, the sulfur signals at 164.5 eV and 163.3 eV were assigned to P-S-P bridging bond and P = S double bond in P 4 S 10 [45] . 162.1 eV and 161.6 eV are appointed to P = S double bond and P-S-Li bridge bond in Li 3 PS 4 , respectively [45,46] . XPS generally collects composition information at a depth of a few nanometers on the surface of the material, while Raman could get information at a depth of a few microns.…”