Building a rational nanoarchitecture of a quantum dots (QDs)/graphene composite is a promising method to satisfy the demands of high sodium-ion storage capacity, good rate capability, and superb cycling stability. Here, a powerful supercritical CO 2 -fluid strategy is provided to fabricate a TiO 2 QDs/reduced graphene oxide (RGO) composite. The prepared nanocomposite shows a porous and stable structure with a tight union of TiO 2 QDs (∼3.7 nm) and RGO supports, which offers numerous fast electron and ion transmission routes and high mechanical stability. When it cycles at 0.05 A g −1 as the anodic material for Na-ion batteries (SIBs), the TiO 2 QDs/RGO electrode shows a reversible capacity of 241 mA h g −1 with a low capacity loss of 18.5% after 300 cycles. Even increasing the current density up to 5 A g −1 , an excellent capacity as high as 108 mA h g −1 still can be achieved with a low capacity loss of 11.5% over 5000 cycles. This work demonstrates a new supercritical CO 2 -fluid-assisted strategy for future development of brilliant QDs/RGO composite materials for high-performance SIBs.
Silicon is considered as an ideal anode material for the next generation of lithium-ion batteries (LIBs) owing to its high specific capacity, low lithiation potential, and high natural abundance. However, its potential application is greatly restricted by poor electrical conductivity and large volume expansion during lithiation/delithiation processes. Herein, a novel solid-state reaction route is developed to synthesize a silicon/carbon nanotubes/carbon (Si/CNTs/C) composite by directly reacting magnesium silicide (Mg 2 Si) with lithium carbonate (Li 2 CO 3 ). This method realizes synchronous formation of Si, CNTs, and amorphous carbon with a good interfacial configuration. Transmission electron microscopy (TEM) reveals that MgO may be responsible for the in situ growth of CNTs during the chemical reaction process. The crystalline Si particles are encapsulated by CNTs and the amorphous carbon matrix, which not only accommodates the volume expansion of Si but also enhances the integral electronic conductivity. Consequently, the Si/CNTs/C composite exhibits a high reversible capacity (702 mA h g −1 at 0.2 A g −1 ), excellent rate performance (420 mA h g −1 at 5 A g −1 ), and long cycling life (over 1500 cycles) when used as an anode for LIBs. Notably, this research might provide a new strategy for large-scale synthesis and utilization of Si/C composites in high-performance LIBs.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.