In Situ Synthesis of a Si/CNTs/C Composite by Directly Reacting Magnesium Silicide with Lithium Carbonate for Enhanced Lithium Storage Capability

Abstract

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.

Supercritical-Assisted Ball-Milling Synthesis of Multicomponent Si/Fe3O4/C Composites for Outstanding Lithium-Storage Capability

“…The high capacitance contribution is attributed to the lamellar structure of graphite and complexation with nano-Fe 3 O 4 , which provides an abundance of active sites for Li + adsorption. 51,52 The fast diffusion kinetics is the key reason for the high capacity and excellent rate performance of Si/Fe 3 O 4 /C composites. The microscopic morphological changes of the electrode could reflect the volume expansion of the Si-based anode visually.…”

“…The capacitance contributes up to 68.17% when the scan rate reaches 2.0 mV s –1 (Figure c). The high capacitance contribution is attributed to the lamellar structure of graphite and complexation with nano-Fe 3 O 4 , which provides an abundance of active sites for Li + adsorption. , The fast diffusion kinetics is the key reason for the high capacity and excellent rate performance of Si/Fe 3 O 4 /C composites.…”

New Chemical Synthesis Strategy To Construct a Silicon/Carbon Nanotubes/Carbon-Integrated Composite with Outstanding Lithium Storage Capability

“…Combining Si with conducting and buffering components is confirmed to be an effective strategy . Carbon nanotubes (CNTs) are characterized by high electrical conductivity and high mechanical strength; therefore, the conductive network constructed by CNTs can improve the electrical conductivity of Si-based materials and provide a buffer component for the volume expansion. − For example, Wei et al combined porous Si, graphene oxide, and CNTs by a rapid freeze-drying and heating treatment method. The resultant Si–rGO/CNTs composite exhibited a unique structure with excellent multiplicative properties and a long cycle life.…”

Insight into the Self-Assembled Three-Dimensional Sandwich-Like Hollow Silicon Nanoarray/Graphene Lithium Storage Architecture by Sonication-Assisted Functionalization

“…The increasing development of technological applications from portable electronics and medical implants to electric vehicles and power storage installations depends upon the high power density of lithium-ion batteries (LIBs). , However, the current commercial graphite-based anodes cannot yet satisfy the increasing need of LIBs in these applications, owing to their low theoretical specific capacity of 372 mAh g –1 . , Therefore, advanced anode materials with higher specific capacities, such as silicon-based, − tin-based, − and other metal-based − materials, have been developed in recent years. Among them, silicon (Si) has been considered as one of the most promising anode materials for next-generation LIBs because of its abundance in nature and being environmental benignity, with a relatively low working potential (∼0.5 V versus Li/Li + ) and a very high theoretical specific capacity of 4200 mAh g –1 , which is over 10 times that of commercial graphite anodes. , However, pure Si anodes suffer from poor electronic conductivity and large volume expansion/contraction (>300%) during Li-ion insertion/extraction.…”