Preparation and electrochemical properties of flexible self-supported graphene/silicon/carbon nanotube composite electrode for lithium-ion battery.

To meet the demand of flexible devices, it was urgent to develop flexible high-capacity electrodes for lithium-ion batteries (LIBs). Silicon (Si) as an active material would effectively elevate the specific capacity of LIBs, but the drastic volume changes and low intrinsic conductivity seriously affected its electrochemical performance during the charge-discharge process. In this research, a new type of composite was designed using two-dimensional reduced graphene oxide (rGO), one-dimensional carbon nanotubes (CNTs), and silicon nanoparticles (Si NPs) as raw materials. The prepared rGO/Si/CNTs composite had an intricate and intersecting porous network structure inside, with rGO as the substrate, CNTs as a bridge, and Si NPs as the active material. The rGO would provide abundant attachment sites for Si NPs, improve electrode conductivity, and alleviate the volume change of electrode. CNTs can effectively suppress the stacking of rGO layers and generate more voids for the reaction, and also serve as a bridge for electron transfer between rGO layers. Furthermore, the interaction between each other also heightened the flexibility and strength of electrodes. Compared to the other composites, rGO/Si/CNTs=2:2:1 electrodes presented the superior electrochemical performance. When cycled at 200 mA g−1, its discharge capacity was 2217.2 mAh g−1 after 200 cycles. As the current density increasing to 1000 and 5000 mA g−1, the discharge capacity maintained at 1877.2 and 534.8 mAh g−1 for 1000th cycle, and it also demonstrated superior rate performance. Besides, the assembled flexible battery maintained a good current output under various bending conditions, and was expected to be widely used in the flexible wearable energy storage devices. [Display omitted] • An intricate and intersecting porous network structure was prepared to fix Si NPs. • The rGO and CNTs were applied to increase conductivity and heighten the flexibility and stability of electrodes. • The rGO/Si/CNTs=2:2:1 anode exhibited 534.8 mAh g−1 at the high current density of 5000 mA g−1 after 1000 cycles. • The assembled flexible battery of rGO/Si/CNTs=2:2:1 maintained a good current output under various bending conditions. [ABSTRACT FROM AUTHOR]