Solid Electrolyte Interphase Layer Formation on the Si-Based Electrodes with and without Binder Studied by XPS and ToF-SIMS Analysis

Abstract

The formation and evolution of the solid electrolyte interphase (SEI) layer as a function of electrolyte and electrolyte additives has been extensively studied on simple and model pure Si thin film or Si nanowire electrodes inversely to complex composite Si-based electrodes with binders and/or conductive carbon. It has been recently demonstrated that a binder-free Si@C-network electrode had superior electrochemical properties to the Si electrode with a xanthan gum binder (Si-XG-AB), which can be principally related to a reductive decomposition of electrolytes and formation of an SEI layer. Thus, here, the Si@C-network and Si-XG-AB electrodes have been used to elucidate the mechanism of SEI formation and evolution on Si-based electrodes with and without binder induced by lithiation and delithiation applying surface analytical techniques. The X-ray photoelectron spectroscopy and time-of-flight ion mass spectrometry results demonstrate that the SEI layer formed on the surface of the Si-XG-AB electrode during the discharge partially decomposes during the subsequent charging process, which results in a less stable SEI layer. Contrarily, on the surface of the Si@C-network electrode, the SEI shows less significant decomposition during the cycle, demonstrating its stability. For the Si@C-network electrode, initially, the inorganic and organic species are formed on the surface of the carbon shell and the silicon surface, respectively. These two parts of species in the SEI layer gradually grow and then fuse when the electrode is fully discharged. The behavior of the SEI layer on both electrodes corroborates with the electrochemical results.

Superior compatibility of silicon nanowire anodes in ionic liquid electrolytes

“…Therefore, the presence of a FEC mole fraction > 0.01 in IL electrolytes seems to support larger consumption of electrolytes and/or hinder the formation of an optimal SEI onto the Sn-Si NW surface. As reported in the literature [54,55] , the uncoordinated FEC can passivate the anode surface by forming LiF, which can undergo the formation of HF in the presence of small amount of water, causing the dissolution of the SEI on the Si anode surface. However, more prolonged discharge-charge tests (C) reveal progressive decay in performance.…”

Evaluation of solid electrolytes: Development of conventional and interdisciplinary approaches

“…The depth profiling and surface imaging by time-of-flight secondary-ion mass spectrometry (ToF-SIMS) were applied for the anode/SE interfaces qualitative analysis. [7,9,71,[130][131][132][133] 23A. The signal concentrations/counts of Li 2 O and Li 3 N are homogeneously and higher than Li 3 P and Li 2 S chemical species.…”

“…The depth profiling and surface imaging by time‐of‐flight secondary‐ion mass spectrometry (ToF‐SIMS) were applied for the anode/SE interfaces qualitative analysis. [ 7,9,71,130–133 ] Ahmad et al determined the pre‐SEI composition between the Li/SEs (Li 2.96 P 0.98 S 3.92 O 0.06 –Li 3 N) interfaces. ToF‐SIMS imaging assisted by Cs + ‐ion sputtering shows that chemical species, such as Li, Li 3 P, Li 2 S, Li 3 P, Li 3 N, and Li 2 O are homogeneously dispersed on the surface of the Li‐metal in Figure 23A.…”

A Steric-Hindrance-Induced Weakly Solvating Electrolyte Boosting the Cycling Performance of a Micrometer-Sized Silicon Anode

“…The C 1s XPS spectra are shown in Figure d, where the peak located around 282 eV is assigned to the Li–C bond . Not only is the peak representing CO 3 2– quite weak for the film anode cycled in the D3 electrolyte but also the total signal intensity of all carbon species is far weaker when compared to the other two groups.…”

“…The C 1s XPS spectra are shown in Figure 5d, where the peak located around 282 eV is assigned to the Li−C bond. 28 Not only is the peak representing CO 3 2− quite weak for the film anode cycled in the D3 electrolyte but also the total signal intensity of all carbon species is far weaker when compared to the other two groups. After the etching time is increased to 600 s, the total intensity of the C species is reduced to a significantly low level, which means the SEI close to the Si film side is rather barren in organics.…”