Making the Unfeasible Feasible: Synthesis of the Battery Material Lithium Sulfide via the Metathetic Reaction between Lithium Sulfate and Sodium Sulfide.

Lithium sulfide (Li2S) is a highly desired material for advanced batteries. However, its current industrial production is not suitable for large-scale applications in the long run because the process is carbon-emissive, energy-intensive, and cost-ineffective. This article demonstrates a new method that can overcome these challenges by reacting lithium sulfate (Li2SO4) with sodium sulfide. This approach, which seems unfeasible initially because Li2SO4 is barely soluble in ethanol at room temperature, becomes feasible when heated ethanol and an excess amount of Li2SO4 are used. More interestingly, product purification is easier than that in other metathetic reactions, thanks to the poor solubility of Li2SO4. In order to further minimize the overall costs of producing Li2S, the concomitant byproduct LiNaSO4 and the unfinished precursor Li2SO4 are converted into more valuable materials, Li2CO3 and Na2SO4. Moreover, the homemade Li2S is competitive with the commercial Li2S in cathode performance and gains further enhancement when being composited with the Co9S8 catalyst. Thus, this Li2SO4-based metathesis of Li2S has great potential for practical applications.

Green Synthesis for Battery Materials: A Case Study of Making Lithium Sulfide via Metathetic Precipitation.

For some future clean-energy technologies (such as advanced batteries), the concept of green chemistry has not been exercised enough for their material synthesis. Herein, we report a waste-free method of synthesizing lithium sulfide (Li2S), a critical material for both lithium-sulfur batteries and sulfide-electrolyte-based all-solid-state lithium batteries. The key novelty lies in directly precipitating crystalline Li2S out of an organic solution after the metathetic reaction between a lithium salt and sodium sulfide. Compared with conventional methods, this method is advantageous in operating at ambient temperatures, releasing no hazardous wastes, and being economically more competitive. To collect the valuable byproduct out of the liquid phases, a "solventing-out crystallization" technique is employed by adding an antisolvent (AS) of low boiling point. The subsequent distillation of the new solution under vacuum evaporates off the AS rather than the high-boiling-point reaction solvent (RS), saving a lot of energy. Consequently, the separated AS and RS containing the unreacted lithium salt can be directly reused. For industrial production, the entire process may be operated continuously in a closed loop without discharging any wastes. Moreover, Li2S cathodes and sulfide-electrolyte Li6PS5Cl derived from the synthesized Li2S show impressive battery performance, displaying the great potential of this method for practical applications.

Green synthesis of the battery material lithium sulfide via metathetic reactions.

We report a synthesis of lithium sulfide, the cost-determining material for making sulphide solid electrolytes (SSEs), via spontaneous metathesis reactions between lithium salts (halides and nitrate) and sodium sulfide. This innovative method is economical, scalable and green. It will pave the way to developing practical SSE-based solid-state lithium batteries.

PtNi bimetallic nanoparticles loaded MoS2 nanosheets: Preparation and electrochemical sensing application for the detection of dopamine and uric acid.

Composite nanomaterials are particularly useful and offer many excellent opportunities for electrochemical sensing application. Depending on the high catalytic activity of bimetallic nanoparticles, the large specific surface area, abundant active edges and co-catalytic function of MoS2 nanosheets, we, for the first time, prepared a novel PtNi bimetallic nanoparticles loaded MoS2 nanosheets (PtNi@MoS2) hybrid material by a co-reduction method for the electrochemical sensing application. The nanocomposite is characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS), and then casted on a bare glassy carbon electrode (GCE) to fabricate an electrochemical sensor (PtNi@MoS2/GCE). The electrochemical investigation showed that the sensor performed good selectivity and wide linear ranges for the simultaneous detection of dopamine (0.5-150 µM) and uric acid (0.5-600 µM). And the detection limits were down to 0.1 µM (S/N = 3) for both analytes.