The high promise of lithium-sulfur (Li-S) batteries attracts unprecedented interests in recent years. The majority of current investigations concentrate on sulfur-based cathode materials. The use of a sulfur cathode, however, presents several challenges due to the Li metal anode, which is prone to potential dendrite growth, shuttle reactions of Li with polysulfide species, and the reductive decomposition of electrolyte components on Li surface. One holistic strategy to address these problems is to produce batteries with Li2S-based cathodes, with which high-capacity anodes including Si and Sn can be used instead of Li metal. The electrochemical reaction at the Li2S cathode is as same as the sulfur cathode in principle. At the anode side, Li forms alloys with Si or Sn at higher potentials versus Li/Li+ so that the Li dendrite formation can potentially be eliminated. The new batteries of Si-Li2S and Sn-Li2S indeed have lower energy comparing with Li-S batteries due to the lower cell voltage and the lower anode capacity. Nevertheless, they still have much higher specific capacity than the current Li-ion batteries.
The Li2S cathodes also have advantages from the manufacture standpoint comparing with the conventional Li metal anodes (typically Li thin foils), which require sophisticated processes (purification, extrusion, passivation, etc.) due to the high reactivity of Li. On the other hand, Li2S is nonflammable and oxygen stable (still need protection from moisture) so that the manufacturing process may be less demanding. In this study, we present a scalable process to synthesis Li2S-carbon composite cathodes from various lithium salts and organic carbon precursors via aerosol-assisted spray pyrolysis (ASP). The ASP is a robust method to produce Li2S-C composites with rational microstructures from different reactants. The reactions mechanisms and characterizations of the produced Li2S-C cathode will be discussed in details.
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