2025 AIChE Annual Meeting

Optimization of Lithium-Sulfur Batteries through Integration of GDY-Based SACs Under Mild Conditions

As society transitions into the Fourth Industrial Revolution, the demand for portable electronics and electric vehicles has grown rapidly, accelerating the adoption of electrochemical storage. Lithium–sulfur batteries have emerged promisingly due to sulfur’s abundance and light weight, theoretically with greater capacity and energy density than any conventional batteries. However, their commercialization has been limited by their short cycle life and low efficiency caused by sulfur’s poor conductivity and the polysulfide shuttling effect. To address these challenges, this project investigates whether the integration of graphdiyne-based single-atom catalysts (GDY-based SACs) can help trap sulfur and improve conductivity, enhancing the performance of Li–S batteries. GDY-based SACs are commonly synthesized using high-temperature treatment methods; however, this study aims to seek a more efficient synthesis route.

To achieve a low-temperature synthesis condition, a pathway inspired by the ammonia synthesis process using reductive elimination and cross-coupling reactions is introduced, where metal ions deprotonate GDY and become intrinsically trapped between the cross-coupling of GDY monomers. The surface composition of GDY-based SACs is examined by X-ray photoelectron spectroscopy (XPS) and nuclear magnetic resonance (NMR) to verify its formation. The interactions between sulfur and GDY-based SACs are later studied via in situ Raman spectroscopy with analysis of peak shifts and intensity changes during cell cycling. Battery performance is then assessed through galvanostatic charge/discharge testing using standard Li-S batteries as a control. Another test is conducted using cyclic voltammetry to determine whether metal catalysts help reduce sulfur loss by enhancing the kinetics.

We expected that this low-temperature synthesis would be effective with any metal catalyst. Our results showed that the synthesis is successful for copper (I) chloride. However, it did not work for cobalt (II) chloride, despite multiple attempts to vary the temperature and solvent. This outcome was possibly due to the cobalt’s oxidation state. We plan to explore iron (III) chloride and ruthenium (III) chloride for GDY synthesis. In addition, we anticipated that GDY-based SAC batteries would yield higher overall capacity while exhibiting slower drops per cycle. Nonetheless, we found that GDY-based copper did not improve the batteries’ performance significantly. If GDY-based iron and ruthenium can be synthesized under the desired conditions and can effectively mitigate the shuttling effect, our project serves as a springboard for future studies to explore other metal catalysts to optimize Li-S batteries. Otherwise, our project serves as a definite study, preventing further studies that would waste time and resources. This study is important as humans nowadays seek not only technological convenience but also environmental sustainability.