Wood-Derived Carbon Fibers Embedded with SnO x Nanoparticles as Anode Material for Lithium-Ion Batteries

Abstract

Carbon-SnO _x composites are obtained by impregnating acetylacetone-treated, delignified wood fibers with tin precursor and successively carbonizing at 1000 °C in 95% argon and 5% oxygen. Scanning electron microscopy and nitrogen sorption studies (Brunauer-Emmett-Teller) show that acetylacetone treatment stabilizes the wood fiber structure during carbonization at 1000 °C and preserves the porous structural features. X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy studies show that the small amount of oxygen introduced in inert atmosphere passivates the surface of tin nanoparticles. The passivation process yields thermally and electrochemically stable SnO _x particles embedded in carbon matrix. The resultant carbon-SnO _x material with 16 wt% SnO _x shows excellent electrochemical performance of rate capability from 0.1 to 10 A g^-1 and cycling stability for 1000 cycles with Li-ion storage capacity of 280 mAh g^-1 at a current density of 10 A g^-1. The remarkable electrochemical performance of wood-derived carbon-SnO _x composite is attributed to the reproduction of structural featured wood fibers to nanoscale in carbon-SnO _x composite and controlled passivation of tin nanoparticles to yield SnO _x nanoparticles.

Keywords: anode materials; carbon–tin composites; lithium‐ion batteries; tin oxide; wood fibers.

Figure 1

Schematic for synthesis of C–SnO_x composite.

Figure 2

a) XRD of C–SnO_x composite: i) CO–SnO_x@1000 °C, ii) C–SnO_x@1000 °C. b) Raman for i) CO–SnO_x@1000 °C, ii) C–SnO_x@1000 °C, iii) C@1000 °C, iv) CWA@1000 °C.

Figure 3

FESEM of a) C–SnO_x@1000 °C, b) C@1000 °C, c) CO–SnO_x@1000 °C. TEM for d,e) C–SnO_x@1000 °C. Inset of (e) is the HRTEM of CO–SnO_x@1000 °C. f) Selected area diffraction pattern for CO–SnO_x@1000 °C.

Figure 4

XPS for C@1000 °C and C–SnO_x composites. a) C 1s spectra, b) O 1s spectra, and c) Sn 3d spectra.

Figure 5

a) CV for C@1000 °C, C–SnO_x@1000 °C, CO–SnO_x@1000 °C. b) Capacity versus voltage profile for CO–SnO_x@1000 °C at 100 mA g⁻¹ current density.

Figure 6

a) Electrochemical performance comparison of C–SnO_x composites versus C@1000 °C. b) Cycling stability and rate capability of CO–SnO_x@1000 °C with starting current density of 100 mA g⁻¹. c) Cycling stability and rate capability of CO–SnO_x@1000 °C with starting current density of 1 A g⁻¹.