Lithium-sulfur (Li-S) batteries are among the most promising next generation batteries to realize in the near future to meet the demands of electric vehicles and grid storage.  However, the direct use of lithium anode and sulfur cathode confronts safety concerns due to the dendrite growth of lithium metal.  An alternative is to use lithium sulfide (Li₂S) nanomaterials.  However, the commercially available Li₂S exists only as micro-powders, due to the high temperature processes used in the industrial synthesis.

Herein we report a thermodynamically favorable method by taking the advantage of hydrogen sulfide (H₂S), a major industrial waste gas.  Considering the fact that H₂S traditional abatement methods are energy intensive and cost ineffective due to the thermodynamic limitations and low values of the products sulfur and water, it is mutual beneficial to combine the alkali sulfide synthesis with the H₂S abatement.  The synthetic reaction developed is spontaneous and irreversible at ambient temperature and pressure, proceeding to completion very rapidly.  

Specifically, lithium naphthalenide (Li-NAP) in dimethoxyethane (DME) was used to react with H₂S, producing anhydrous Li₂S nanocrystals, and 1,4-dihydronaphthalene, itself a value-added chemical that could be used as liquid fuel.  The phase purity, morphology, and homogeneity of the resulting Li₂S nanopowder was confirmed by X-ray diffraction and scanning electron microscopy.  The synthesized Li₂S nanoparticles (100 nm) were assembled into cathodes and their performance was compared to cathodes fabricated using commercial Li₂S micropowders (1 - 5 µm).  Electrochemical analyses demonstrated that the synthesized Li₂S nanoparticles were superior in terms of (dis)charge capacity, cycling stability, output voltage, and voltage efficiency.