TiO2-Coated Silicon Nanoparticle Core-Shell Structure for High-Capacity Lithium-Ion Battery Anode Materials

Abstract

Silicon-based anode materials are considered one of the highly promising anode materials due to their high theoretical energy density; however, problems such as volume effects and solid electrolyte interface film (SEI) instability limit the practical applications. Herein, silicon nanoparticles (SiNPs) are used as the nucleus and anatase titanium dioxide (TiO₂) is used as the buffer layer to form a core-shell structure to adapt to the volume change of the silicon-based material and improve the overall interfacial stability of the electrode. In addition, silver nanowires (AgNWs) doping makes it possible to form a conductive network structure to improve the conductivity of the material. We used the core-shell structure SiNPs@TiO₂/AgNWs composite as an anode material for high-efficiency Li-ion batteries. Compared with the pure SiNPs electrode, the SiNPs@TiO₂/AgNWs electrode exhibits excellent electrochemical performance with a first discharge specific capacity of 3524.2 mAh·g^-1 at a current density of 400 mA·g^-1, which provides a new idea for the preparation of silicon-based anode materials for high-performance lithium-ion batteries.

Keywords: AgNWs doping; SiNPs@TiO2 core-shell structure; lithium-ion batteries; silicon-based anode materials.

Figure 1

Schematic structure of SiNPs@TiO₂/AgNWs.

Figure 2

Schematic diagram of the preparation process.

Figure 3

(a) SEM image of SiNPs@TiO₂, whose upper right inset shows the particle size distribution of SiNPs@TiO₂, (b) HRTEM image, (c) TEM image, and (d) EDS image.

Figure 4

SiNPs@TiO₂/AgNWs (a) TEM image, and (b) XRD spectrum.

Figure 5

Charge/discharge curves and cyclic voltammetry curves of different anode materials (a,d) SiNPs, (b,e) SiNPs@TiO₂, and (c,f) SiNPs@TiO₂/AgNWs.

Figure 6

SiNPs, SiNPs@TiO₂ and SiNPs@TiO₂/AgNWs (a) cyclic characteristic curves, and (b) EIS, the illustration in the upper left corner shows the equivalent circuit.

Figure 7

SEM images of the surface of different battery cathode materials before and after 100 cycles of charging and discharging (a,d) SiNPs, (b,e) SiNPs@TiO₂, and (c,f) SiNPs@TiO₂/AgNWs.