Paper‐like 100% Si Nanowires Electrodes Integrated with Argyrodite Li6PS5Cl Solid Electrolyte

Silicon anodes are a promising solution in all‐solid‐state batteries (ASSBs) due to minor lithium dendrite risk, high capacity, and low potential. Research on Si integration in ASSBs is still nascent, requiring a deep understanding of the interplay between electrode composition, structure, and performance. Here, we present the first study on 100% Si nanowires integrated with Li6PS5Cl solid electrolyte (SE). The anodes are paper‐like networks of aggregated Si nanowires produced by a slurry‐free method without carbon/binders. Despite the lack of any conductor, the Si anodes provide >2.5 Ah/g capacity at a high mass loading of 1.7 mg/cm2(~5 mAh/cm2), demonstrating sufficient electric and ionic conductivities. Electro‐chemo‐mechanical properties of the electrodes over (de)lithiation were probed through electrochemical impedance spectroscopy, ex‐situ microscopy, and in‐operando pressure regulation measurements. The lithiated electrode/SE interface was found to be electrochemically stable. Cross‐sectional microscopy at various states‐of‐charge confirmed the buffering effect of the anode porosity, resulting in the preservation of the electrode’s thickness after the first lithiation but a considerable shrinkage during delithiation, producing cracking and formation of the new interface. Capacity remains constant for five cycles, then decreases linearly up to 40 cycles. This is attributed to repeated fracture of the anode/electrolyte interface and the corresponding impedance increase