Stabilising graphite anode with quasi-solid-state electrolyte for long-life lithium-sulfur batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium-sulfur (Li-S) batteries offer high energy density but face challenges with lithium metal anode instability and poor cycle life.
• Graphite anodes, common in lithium-ion batteries, are desirable for Li-S systems but incompatible with ether-based electrolytes due to ion/solvent co-intercalation.
• This incompatibility leads to graphite exfoliation, hindering the development of stable and efficient Li-S batteries.

Purpose of the Study:

• To stabilize graphite anodes in Li-S batteries by developing a novel in-situ formed quasi-solid-state electrolyte (QSSE).
• To overcome the electrolyte incompatibility issue that prevents the use of graphite anodes in ether-based electrolytes for Li-S batteries.
• To enable the use of safe, cost-effective, and stable graphite anodes in next-generation Li-S energy storage systems.

Main Methods:

• Developed an in-situ QSSE by inducing ring-opening of molecular ethers using a molybdenum disulfide sulfur cathode host.
• The QSSE forms a gel polymer matrix with ionic conductivity (1.51 mS cm⁻¹) comparable to liquid electrolytes.
• Investigated the electrochemical performance of Li-S pouch cells using the in-situ QSSE and graphite anode.

Main Results:

• The in-situ formed QSSE effectively prevents Li⁺ ion and solvent co-intercalation into the graphite anode.
• The QSSE exhibits sufficient ionic conductivity and redox chemistry for the sulfur cathode.
• Li-S pouch cells demonstrated a specific capacity of ~1200 mAh g⁻¹ and 90.3% capacity retention over 200 cycles.

Conclusions:

• The in-situ formation of QSSE successfully stabilizes graphite anodes in Li-S batteries with ether-based electrolytes.
• This approach resolves the electrolyte limitation, paving the way for graphite anode utilization in Li-S batteries.
• The developed technology offers a pathway towards safer, more cost-effective, and stable Li-S batteries for advanced energy storage.