Sulfide solid state electrolyte (SSE) possesses high ionic conductivity and great processability but suffers from narrow electrochemical window. Conversion sulfide cathode FeS2 has higher specific capacity and moderate redox potential, making it appropriate towards sulfide SSE. However, the complex reaction pathway and capacity fading mechanism in FeS2 are rarely studied, especially in all-solid-state lithium battery (ASSLB). Herein, argyrodite sulfide SSE is paired with FeS2 to investigate the electrochemical reaction pathways and the capacity fade mechanism. Instead of single conversion reaction, an anionic redox driven reaction of FeS2 is revealed. The oxidization of Li2S vanishes and large quantity of inactive Li2S accumulates to cause the interfacial deterioration, along with the stress concentration during cycling, which leads to the rapid capacity fade of FeS2. Finally, a simple strategy of slurry-coated composite electrode with highly conductive network is proposed to direct the uniform deposition of Li2S and alleviate the stress concentration.
Despite of superior performance of the oxide-derived copper (OD-Cu) in producing valuable hydrocarbons during CO2RR, its fabrication process is still ambiguous and complicated. In this work, we develop a simple microwave-assisted method to synthesize the oxide-derived Cu nanosheet (OD-Cu NS) and reveal that the oxidation state of Cu species is controlled by varying the Cu precursor amount. Notably, the simultaneous formation of nano-sized Cu domains influence the surface roughness of OD-Cu NS. The partially oxidized Cu surface exhibits a superior faradaic efficiency (FE) of C2+ products up to 72%, along with a partial current density of 55 mA cm−2 in a neutral KHCO3 solution. More importantly, the as-obtained OD-Cu NS shows a synergetic effect on dissociating of CO2 molecules by the strong binding energy and promoting of C2+ compounds productivity by the enlarged electrochemical surface area. This work provides a new insight for designing efficient OD-Cu catalysts towards CO2RR.
An effective method for obtaining large amounts of metal nanoparticles encapsulated by carbon layers through upcycling from floating-catalyst aerosol chemical vapor deposited carbon nanotubes is demonstrated. Nanoparticles with diameters of less than 20 µm are selectively extracted from the synthesized carbon assortments through sonication, centrifugation, and filtration. The particles show an aggregation behavior owing to the π–π interaction between the graphitic carbon shells surrounding the iron carbides. By controlling the degree of the aggregation and arrangement, the light scattering by the gap-surface plasmon effect in perovskite solar cells is maximized. Application of the nanoparticles to the devices increased the power conversion efficiency from 19.71% to 21.15%. The short-circuit current density (JSC) trend over the particle aggregation time accounts for the plasmonic effect. The devices show high stability analogue to the control devices, confirming that no metal-ion migration took place thanks to the encapsulation.