The PULSELiON project proudly announces its 28th Open Access publication, contributing new insights into the fundamental electronic behavior of sulfide-based solid electrolytes for all-solid-state batteries (ASSBs).
The paper, titled “When Electrolytes Are Semiconductors: A Feature, Not a Bug for Solid-State Batteries”, has been published in Batteries (2026, Volume 12, Article 60) and is available Open Access.
Understanding the semiconductor nature of solid electrolytes
Solid electrolytes are often assumed to behave as perfect electronic insulators. However, this work demonstrates that three highly promising sulfide electrolytes — Li₆PS₅Cl (LPSCl), Li₆PS₅Br (LPSBr), and Li₁₀GeP₂S₁₂ (LGPS) — actually exhibit semiconductor-like behavior with wide band gaps.
The study combines Density Functional Theory (DFT) and hybrid functional (HSE06) simulations with advanced electrochemical characterization methods, including:
- Scanning Kelvin Probe Microscopy (SKPM)
- Potentiostatic Electrochemical Impedance Spectroscopy (PEIS)
- Cyclic Voltammetry (CV)
- Surface potential and charge distribution analyses
The results reveal how charge transfer, electron tunneling, and interfacial reactions occur within sulfide electrolytes and at electrode/electrolyte interfaces. Rather than representing a drawback, the semiconducting nature of these materials may actually support the formation of stable solid electrolyte interphases (SEIs) and improve battery operation.
Key findings
Among the investigated electrolytes, LPSCl showed the most favorable balance between stability, electronic properties, and compatibility with lithium metal.
The research also demonstrates that:
- Sulfide electrolytes exhibit measurable semiconductor-like band structures
- Surface potential measurements reveal interfacial charge transport phenomena
- Electrolyte electronic structure strongly influences electrochemical stability
- Combined theoretical and experimental approaches are essential for designing next-generation ASSBs
These findings provide important guidelines for optimizing solid electrolytes and improving the long-term stability and safety of solid-state battery technologies.
Contribution from PULSELiON
The work was carried out by researchers from the University of Porto, including Beatriz M. Gomes, Manuela C. Baptista and M. Helena Braga, within the framework of the PULSELiON project