Solid-State Li-Ion Batteries Operating at Room Temperature Using New Borohydride Argyrodite Electrolytes

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Batteries

Background:

• Developing stable and efficient solid electrolytes is crucial for advancing solid-state batteries.
• Lithium-metal batteries offer high energy density but face challenges with dendrite formation and interfacial stability.

Purpose of the Study:

• To develop and evaluate a new class of (BH4)- substituted argyrodite solid electrolytes for room-temperature lithium-metal solid-state batteries.
• To compare the performance of oxide (NMC) and titanium disulfide (TiS2) cathodes when paired with the novel solid electrolyte.

Main Methods:

• Synthesis of Li6PS5Z0.83(BH4)0.17 (Z = Cl, I) solid electrolytes.
• Fabrication of solid-state cells using In-Li anode, modified argyrodite electrolyte, and either NMC or TiS2 cathode.
• Performance evaluation via galvanostatic cycling and AC electrochemical impedance spectroscopy.

Main Results:

• Both NMC and TiS2 cathodes demonstrated reversible capacities over tens of cycles.
• The TiS2 cathode exhibited superior cycling stability and lower capacity fading compared to the NMC cathode.
• AC impedance measurements indicated increasing interfacial resistance for the NMC cathode, attributed to poor conductivity and interfacial reactions.
• The TiS2 cathode showed low interfacial resistance, suggesting good chemical compatibility with the substituted argyrodite electrolyte.

Conclusions:

• The novel (BH4)- substituted argyrodite electrolytes are promising for room-temperature solid-state batteries.
• Titanium disulfide (TiS2) demonstrates better electrochemical performance and stability as a cathode material compared to NMC when used with these electrolytes.
• Minimizing interfacial resistance is key to achieving high-performance solid-state batteries.