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Carbon coatings can help to stabilize the electrochemical performance of high-energy anodes using silicon nanoparticles as the active material. In this work, the comparison of the behavior and chemical composition of the Solid Electrolyte Interphase (SEI) was carried out between Si nanoparticles and carbon-coated Si nanoparticles (Si@C). A combination of two complementary analytical techniques, Electrochemical Impedance Spectroscopy and X-ray Photoelectron Spectroscopy (XPS), was used to determine the intrinsic characteristics of the SEI. It was demonstrated that the SEI on Si particles is more resistive than the SEI on the Si@C particles. XPS demonstrated that the interface on the Si particles contains more oxygen when not covered with carbon, which shows that a protective layer of carbon helps to reduce the number of inorganic components, leading to more resistive SEI. The combination of those two analytical techniques is implemented to highlight the features and evolution of interfaces in different battery technologies. [ABSTRACT FROM AUTHOR]

Bringing solid-state lithium batteries to market is a challenge; in part because their fabrication requires a technically difficult step of solid-electrolyte separator assembly, and because thus far, solid-state cells have only cycled under high pressure. Here, we address both these bottlenecks by assembling lithium-ion batteries based on the argyrodite Li 6 PS 5 Cl as the electrolyte using standard coating processes. Moreover, we upscaled to 10 cm2 pouch cells in a dry room by a double casting technique, thanks to the use of fluorine-free polyisobutene as the binder and nanosilicon and LiNi 0.6 Mn 0.2 Co 0.2 O 2 (NMC622) respectively as the anode and cathode active materials. Electrode casting is shown to significantly improve the cycling stability when compared to the conventional pelletizing process. The all-coated pouch cells, cycled at a pressure as low as 1 MPa over 160 cycles, show a better capacity retention than the pelletized cells cycling under >100 MPa. The higher performance of the sheet-type cell is thought to originate in the better densification and homogeneity of the cell, attested by its low resistance. [Display omitted] • Si-NMC pouch cells with Li 6 PS 5 Cl solid electrolyte. • Both electrodes and separator casted via conventional ink coating process. • Cell scaled up from 0.4 cm2 (pelletized cell) to 10 cm2 (all-coated pouch cell). • The coating process improved long-term stability. • Pouch cells cycled under 1 MPa perform better than pelletized cells at 127 MPa. [ABSTRACT FROM AUTHOR]

Thanks to their high ionic conductivity and appropriate mechanical properties, sulfide-based solid electrolytes (SSE) are increasingly studied for a use in all-solid-state batteries (ASSBs). Silicon is abundant, non toxic and has a high theoretical capacity, and therefore is a promising active material in ASSBs. We first study the compatibility between two different solid electrolytes with similar ionic conductivity, Li 10 SnP 2 S 12 (LSnPS) and Li 6 PS 5 Cl (LPSCl), and micron-sized silicon based anode. LPSCl appears to be less reactive than LSnPS and it is then used to determine the most appropriate silicon size and shape for efficient cycling. Two silicon materials are compared, micron-sized silicon particles (μSi) and silicon nanowires (SiNWs). Energy Dispersive X-ray spectroscopy (EDX) mapping of the composite powders shows a better dispersion of the SiNWs in the LPSCl matrix. Galvanostatic cycling and Electrochemical Impedance Spectroscopy (EIS) measurements highlight the greater compatibility of SiNWs compared to μSi in ASSBs with a high specific delithiation capacity of 2600 mAh/g Si at the first cycle, while limiting the polarization and maintaining a relatively stable lithiation mechanism during cycling. [Display omitted] • Comparing solid electrolytes Li 10 SnP 2 S 12 and Li 6 PS 5 Cl for reactivity to Si. • Thinner SEI formed on Si nanowires. • Si nanowires more suitable for ASSB cycling than micron-sized Si. [ABSTRACT FROM AUTHOR]