Supplementary material

High Nitrogen Doped Carbon Nanofiber Aerogels for Sodium Ion

Batteries: Synergy of Vacancy Defects to Boost Sodium Ion Storage

Yun Lua,c,, Daohao Lib, Chunxiao Lyub, Hongli Liub, Bo Liua, Shaoyi Lyua,

Thomas Rosenauc*, Dongjiang Yangb,d,*

a Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing 100091, China.

b Collaborative Innovation Center for Marine Biomass Fibers, Materials and Textiles of

Shandong Province, School of Environmental Science and Engineering, Qingdao University,

Qingdao 266071, China.

c Division of Chemistry of Renewables, Department of Chemistry, Natural Resources and Life

Sciences, Vienna, (BOKU), Vienna A-1190, Austria.

d Queensland Micro- and Nanotechnology Centre (QMNC), Griffith University, Nathan,

Brisbane, Queensland 4111, Australia

Corresponding author. E-mail: y.lu@caf.ac.cn (Y. Lu), d.yang@qdu.edu.cn (D. Yang),

thomas.rosenau@boku.ac.at (T. Rosenau)

Experimental procedures

Characterization

The morphologies of the samples were characterized by field emission scanning electron

microscopy (FESEM; JSM-7001F, JEOL, Tokyo, Japan), transmission electron microscopy

(TEM), high-resolution TEM (FEI Tecnai G20, USA with an accelerating voltage of 200 kV)

and atomic force microscope (AFM, Veeco Di Multimode SPM, Veeco Instruments Inc.,

Plainview, New York, USA, by using a Nanoscope IIIa multimode scanning probe

microscope under tapping mode). The samples were analyzed by Fourier transform infrared

spectroscopy (FTIR; U-4100, Hitachi Instruments Ltd., Japan) in the wavelength range of

400–4000 cm–1 and Solid-state 13C nuclear magnetic resonance (NMR; Varian Inc., USA)

with cross polarization/magic angle spinning (CP/MAS). The specific surface area was

calculated by the Brunauer-Emmett-Teller (BET) method (AutoChem II 2920, USA) from the

data in a relative pressure (P/P0) range between 0.05 and 0.20. The pore size distribution plots

were derived from the adsorption branch of the isotherms based on the BJH model. The phase

structures were characterized with X-ray diffraction (Bruker D8 Adv, Germany) operating

with Cu Kα radiation (l=1.5418 Å) at a scan rate (2θ) of 1° min−1 with an accelerating voltage

of 40 kV. Thermogravimetric analysis (TGA) measurement was carried out on an EXSTAR

TG/DTA 6300 instrument (Seiko Instruments, Japan) in air. Raman spectroscopies were

obtained on a LabRAM HR, Horiba Yvon Raman spectrometer with the 633 nm irradiation

light excitation line of the He-Ne laser. X-ray photoelectron spectroscopies (XPS) were

performed using the SSX-100 ESCA spectrometer operating with monochromatized Al Kα

X-rays (hν=1486.6 eV). The C 1s binding energy (284.8 eV) of adventitious hydrocarbon was

used as an internal standard in calibration.

Figure S1. The TG and DTG patterns of HN-CFA.

Figure S2. The Coulombic efficiency of first ten cycles of A-HN-CFA.

Figure S3. Comparison of specific capacity and cycle life between A-HN-CFA and recently reported high-performance carbon nanofiber as anodes for NIBs.

Figure S4. Characterization of A-HN-CFA after cycled for 5000 cycles. a) TEM image; b) HRTEM image of a single nanofiber.

Figure S5. (a) XRD patterns, (b) N2 adsorption/ desorption isotherms, and (c) the pore size distribution of A-N-CFA.

Figure S6. Optimized structures of N-doped graphene for (a) NG and (b) N5.

Figure S7. Optimized structures of N-doped graphene for (a) N6-N5-2, (b) N6-N5-3, and (c) N6-N5-4.

Figure S8. Optimized structures of N-doped graphene for (a) N6-NG-1, (b) N6-NG-2, (c) N6-NG-3, (d) N6-NG-4, (e) N6-NG-5, (f) N6-NG-6, (g) N6-NG-7, (h) N6-NG-8, and (i) N6-NG-9.

Figure S9. Optimized structures of N-doped graphene for (a) N5-NG-1, (b) N5-NG-2, and (c) N5-NG-3.

Figure S10. Optimized structures of N-doped graphene for (a) N6-N5-NG-2, (b) N6-N5-NG-3, (c) N6-N5-NG-4, (d) N6-N5-NG-5, (e) N6-N5-NG-6, (f) N6-N5-NG-7, (g) N6-N5-NG-8, (h) N6-N5-NG-9, (i) N6-

N5-NG-10, (j) N6-N5-NG-11, (k) N6-N5-NG-12, (l) N6-N5-NG-13, and (m) N6-N5-NG-14.

Figure S11. Calculated the density of states of N6, N6-N5-1, and N6-N5-NG-1.

Table S1. The percentage content of nitrogen in biomass derived N-doped carbon aerogels from XPS results

Samples N content (at%)

HN-CFA 12.2%

A-HN-

CFA 5.3%

A-N-CFA 7.1%

Table S2. Texture properties of chitin nanofiber aerogels and biomass derived N-doped carbon aerogels.

Samples

BET surface area

(m2 g-1)

Pore width

(nm)

Micropore volume

(cm3 g-1)

Pore volume

(cm3 g-1)

Chtin

nanofiber 5.88 37.06 0.001 0.008

HN-CFA 65.27

2.95, 17.21,

37.06 0.004 0.232

A-HN-CFA 746.16

1.76, 17.21,

34.33 0.111 0.899

A-N-CFA 696.03 0.83, 2.4 0.095 0.532

Table S3. The binding energies of the different sites in the N6-N5 models.

Models Site-1/eV Site-2/eV Site-3/eV Site-4/eV Site-5/eV Site-6/eV

N6-N5-

2

-0.171 -0.177 -0.130 -0.175 -0.175 -0.135

N6-N5-

3

-0.519 -0.510 -0.511 -0.510 -0.522 -0.521

N6-N4-

4

-0.790 -0.772 -0.771 -0.773 -0.783

Table S4. The binding energies of the different sites in the N6-NG models.

Models Site-1/eV Site-2/eV Site-3/eV Site-4/eV Site-5/eV Site-6/eV

N6-NG-2 -0.909 -0.906 -0.911 -0.910 1.364

N6-NG-3 -0.887 -0.885 -0.879 -0.887 1.889

N6-NG-4 -0.818 -0.819 -0.818 1.982 1.447

N6-NG-5 -0.815 -0.797 -0.803 -0.816 -0.798

N6-NG-6 -0.886 -0.884 -0.880 -0.880 -0.881 -0.884

N6-NG-7 -0.826 -0.828 -0.828 2.051 -0.826

N6-NG-8 -0.836 -0.840 -0.837 -0.837 1.904

N6-NG-9 -0.771 -0.772 -0.767 1.941 -0.771

Table S5. The binding energies of the different sites in the N5-NG models.

Models Site-1/eV Site-2/eV Site-3/eV Site-4/eV Site-5/eV Site-6/eV Site-7/eV Site-8/eV Site-9/eV

N5-NG-1 -0.046 1.772 -0.036 -0.046 -0.048 -0.039 -0.040 -0.043

N5-NG-2 -0.038 -0.039 -0.032 -0.033 -0.035 1.231 -0.039 -0.035

N5-NG-3 -0.195 -0.198 -0.199 -0.197 -0.191 -0.198 -0.198 -0.193 -0.196

Table S6. The binding energies of the different sites in N6-N5-NG models.Models Site-1/eV Site-2/eV Site-3/eV Site-4/eV Site-5/eV Site-6/eV

N6-N5-NG-3 -1.311 -1.312 -1.311 -1.306 -1.313 -1.312

N6-N5-NG-4 -1.280 -1.285 -1.278 -1.286 -1.280 -1.282

N6-N5-NG-5 -1.149 -1.142 -1.148 -1.133 -1.144 -1.140

N6-N5-NG-6 -1.052 -1.051 -1.050 -1.050 -1.051 -1.050

N6-N5-NG-7 -1.176 -1.173 -1.173 -1.173 -1.173 -1.173

N6-N5-NG-8 -1.531 -1.530 -1.531 -1.531 -1.531 -1.531

N6-N5-NG-9 -1.312 -1.317 -1.312 -1.312 -1.317 -1.312

N6-N5-NG-10

-1.280 -1.281 -1.281 -1.280 -1.282-1.280

N6-N5-NG-11 -1.172 -1.174 -1.173 -1.172 -1.171 -1.168

N6-N5-NG-12

-1.280 -1.276 -1.277 -1.281 -1.279-1.273

N6-N5-NG-13

-1.316 -1.315 -1.316 -1.314 -1.322-1.311

N6-N5-NG-14

-1.399 -1.424 -1.422 -1.426 -1.413-1.425