**4. Conclusions**

In this work, we successfully synthesized hierarchical porous and Si/N co-doped carbon nanofiber anodes. SEM images and nitrogen adsorption–desorption tests confirm that a hierarchical porous structure exists in carbon nanofiber materials, and the EDS mapping confirms that Si and N elements are doped into carbon nanofiber materials. Compared with other anodes, the CNFs-Si10% anode obtained has a high initial reversible specific capacity, high capacity retention, and excellent rate performance in lithium-ion batteries. This excellent electrochemical performance is mainly due to the fact that Si doping can improve specific capacity, N doping can improve conductivity, and the fabricated hierarchical porous structure can increase the number of reactive sites, improve the ion transport rate, and enable the electrolyte to penetrate the inner part of carbon nanofibers to improve the electrolyte/electrode contacting area during charging–discharging processes. This work provides a new avenue for developing flexible anode materials for lithium-ion batteries with high performance.

**Author Contributions:** Y.C.: conceptualization, methodology, writing—original draft; J.W.: software, data curation; X.W.: cell fabrication and testing; X.L.: supervision, data interpretation, writing—review & editing; J.L. (Jun Liu): conceptualization; J.L. (Jingshun Liu): methodology; D.N. methodology; J.D.: supervision, data interpretation. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was financially supported by Natural Science Foundation of Inner Mongolia (no. 2019MS05068), Inner Mongolia Major Science and Technology Project (no. 2020ZD0024), Scientific Research Project of Inner Mongolia University of Technology (no. ZZ202106), the Alashan League's Project of Applied Technology Research and Development Fund (no. AMYY2020-01), the research project of Inner Mongolia Electric Power (Group) Co., Ltd. for post-doctoral studies, Program for Innovative Research Team in Universities of Inner Mongolia Autonomous Region (no. NM-GIRT2211), Inner Mongolia University of Technology Key Discipline Team Project of Materials Science (no. ZD202012), Inner Mongolia Natural Science Cultivating Fund for Distinguished Young Scholars (no. 2020JQ05), Science and Technology Planning Project of Inner Mongolia Autonomous Region (no. 2020GG0267), and Local Science and Technology Development Project of the Central Government (no. 2021ZY0006).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
