Morphological and structural evolution of Si-Cu nanocomposites by an instantaneous vapor-liquid-solid growth and the electrochemical lithiation/delithiation performances

Accommodation of Silicon in an Interconnected Copper Network for Robust Li‐Ion Storage

“…The cathodic peaks at ≈0.01 and 0.19 V are attributed the alloying reaction between Si and Li, while the anodic peaks at ≈0.36 and 0.54 V refer to the delithiation process of Li‐Si alloy 37. No redox peaks are detected for Cu 3 Si,8,38 further confirming the low content of Cu 3 Si and metallic Cu in C‐SCP. The intensity of all redox peaks in the CV profiles increases gradually during cycling because of the activation of active materials.…”

“…In the transmission electron microscope (TEM) images, as shown in Figure S2 (Supporting Information), both C‐SCP and Si/C exhibit typical core–shell structures, in which the inner core (i.e., Si NP) of C‐SCP appears much darker, suggesting existence of heavy elements on the surface of Si NPs. Due to the large lattice mismatch between Si and C,8,17 interfacial energy is readily generated at the interfaces of Si/C materials. In this work, considering that the carbothermic reaction is carried out at temperatures close to the melting point of Cu (1380 K),18 it is reasonable to infer that the metallic Cu melts and tend to diffuse toward the Si/C interfaces under the driven of Si/C energy at high temperatures and forms CCI during the cooling process.…”

“…Diffraction peaks in the spectrum of C‐SCP can be assigned to the (201), (012), and (300) of Cu 3 Si (JCPDS No. 51–0916),8,27 corresponding to interlayer spacing of 0.245, 0.203 and 0.201 nm, respectively. It's reasonable that Cu 3 Si is the solitary compound of Si‐Cu composite, for its formation enthalpy (−13.6 kJ mol −1 ) is the lowest among all Si‐Cu compounds 8,28.…”

“…51–0916),8,27 corresponding to interlayer spacing of 0.245, 0.203 and 0.201 nm, respectively. It's reasonable that Cu 3 Si is the solitary compound of Si‐Cu composite, for its formation enthalpy (−13.6 kJ mol −1 ) is the lowest among all Si‐Cu compounds 8,28. Meanwhile, the existence of Cu 3 Si proves the strong interaction between the Cu layer and Si NP in C‐SCP, which is favorable for enhancing fast electron collection, considering that the electrical resistivity of Cu 3 Si (5.5 × 10 −5 Ω cm) is much lower than that of Si (6 × 10 4 Ω cm) 29.…”

“…In regard to the electronic conductivity, the disadvantage of the limited electron transport efficiency did not stand out in electrode materials with high electrical conductivity, such as graphite (10–10 4 S cm −1 ) 7. However, things are totally different for electrodes with low electrical conductivity, including but not limited to the next‐generation Si‐based anodes (less than 10 −5 S cm −1 ) 8…”