Lithium-sulfur (Li-S) battery is the future of energy storage. Li-S batteries are a potential alternative to contemporary lithium-ion (Li-ion) batteries for applications including power tools, electric vehicles, consumer electronic appliances, grid-scale energy storage, and other energy harvesters. Using sulfur in Li-S batteries provides five times the energy density (2600 Wh kg^-1) of conventional Li-ion battery chemistry.¹ Additionally, an economical raw material like sulfur is essential to achieve the target cost of 61 $ kWh^-1 for electric vehicles by 2030². A significant challenge encountered in Li-S battery chemistry is the sluggish cathode interface kinetics. To circumvent the latter, tailored nanomaterials that can provide active sites that accelerate electrode interface reactions are essential. Herein, we report an amorphous MoS₃ that exhibits sulfur-like electrochemical behavior and produces MoS₂ electrocatalyst that propels redox kinetics in Li-S battery chemistry. MoS₃ cathode was obtained via a single step thermal decomposition of ammonium tetrathiomolybdate ((NH₄)₂MoS₄) precursor at 250 °C. Post-test characterizations such as X-ray diffraction and scanning electron microscopy confirms amorphous (MoS₃) to crystalline (MoS₂) transformation of the cathode during cycling. In battery testing the cathode was rate capable to 10 C. The cathode demonstrated a long-term cyclability of 200 cycles at a rate of 2 C with a gravimetric capacity of ~800 mAh g^-1.³ The capacity fade rate per cycle observed was 0.1%. Similar experiments were carried out with WS₃ analog. The in-situ produced WS₂ electrocatalyst enabled a Li-S battery rate capable up to 2 C with a reduced capacity fade rate of 0.03% per cycle.⁴

References

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2. Battery Pack Prices Fall As Market Ramps Up With Market Average At $156/kWh In 2019 | BloombergNEF. Available at: https://about.bnef.com/blog/battery-pack-prices-fall-as-market-ramps-up-with-market-average-at-156-kwh-in-2019/. (Accessed: 20th December 2020)
3. Abraham, A. M., Kammampata, S. P., Ponnurangam, S. & Thangadurai, V. Efficient Synthesis and Characterization of Robust MoS ₂ and S Cathode for Advanced Li–S Battery: Combined Experimental and Theoretical Studies. ACS Appl. Mater. Interfaces 11, 35729–35737 (2019).
4. Abraham, A. M., Ponnurangam, S. & Thangadurai, V. Facet-Engineered Tungsten Disulfide for Promoting Polysulfide Electrocatalysis in Lithium–Sulfur Batteries. Inorg. Chem. 6, 35 (2021).