In this manuscript, the authors studied the impacts of thermal annealing on the physical and electrochemical properties of carbon-coated silicon (Si) anode. The heat treatment impacts on the solid-electrolyte interphase (SEI) formation and evolution were critically studied by using ex-situ and in-situ Raman spectroscopy techniques. This research is interesting and could address some technique concerns on the heat treatment of Si-based materials in battery research. However, there remain some evidence to support the conclusions in this study. I have following questions regarding to the characterization techniques.

1. The authors conducted FTIR and Raman to characterize the materials, however, the evidence of silicon carbide (Si-C) might be not enough for comparison. To further conform the formation of silicon carbide (Si-C) after heating the Si/pitch samples over 700 ℃, more evidence from other physical characterizations such as XRD and XPS are suggested to be provided.

2. Page 8, for the ATR-FTIR analysis of the chemical changes of pitch carbon after thermal treatment (Fig.1b), references should be added to support some conclusions like “a loss of aliphatic groups” and “a less substituted pitch carbon with more poly-aromatic hydrocarbon (PAH) character”.

3. What are the mass fractions of Si in the three electrodes (Si/pitch, 700 ℃ and 1000 ℃ annealed materials) for the electrochemical tests? Why did the authors set 600 mAh/g as 1C for the cell tests within 0.01-1.5 V and 350 mAh/g as 1C within 10 to 750 mV? Considering the Si content in each electrode could be very different, the applied current may have a big difference regarding to the Si content.

4. To further confirm the impact of heating treatment on the electronic resistivity and conductivity of Si/pitch electrodes, electrochemical impedance spectroscopy (EIS) tests should be also conducted? Since the Si/pitch electrodes also show a decrease in resistivity after heat treatment, we find see a similar trend from EIS results.

5. The authors illustrated the heterogeneous aging behaviors of the Si/pitch-700 electrodes in Figure 6. Post-mortem SEM images of the electrodes are suggested to conduct, which could further support the conclusion.

The authors have addressed all of my concerns. Therefore, I recommend that this manuscript be accepted for publication in Journal of Materials Chemistry A.