Si/C nanocomposite anode materials by freeze-drying with enhanced electrochemical performance in lithium-ion batteries

Abstract

The nanostructured Si/graphite composites embedded with the pyrolyzed polyethylene glycol was synthesized from coarse silicon and natural graphite by a facile and cost-effective approach. The Si/C nanocomposite showed the fluffy carbon-coated structure, which was confirmed by the SEM and TEM measurements. The as-obtained Si/C nanocomposite, employed as anode material in lithium-ion batteries, exhibited significantly enhanced rate capability and cycling stability. The improved electrochemical stability of the composite was evaluated by EIS and galvanostatically charge/discharge test. A reversible capacities as high as 85% and 91% of the initial charge capacities, could be maintained for the Si/C nanocomposite electrode after 40 cycles under the high current densities of 500 and 1,000 mA g −1 , respectively. The relatively low cost and excellent electrochemical capability of the Si/C nanocomposite would well meet the challenge in rapid charge and discharge for large-size lithium-ion rechargeable batteries.

Enhanced electrochemical performances of silicon nanotube bundles anode coated with graphene layers

“…4(a)). Increase in capacity at later cycles has also been reported in other carbon coated anode materials [18,19], however, the reason remains unknown.…”

Templated magnesiothermic synthesis of silicon nanotube bundles and their electrochemical performances in lithium ion batteries

“…It has been considered that the reduction peak at 0.6-0.8 V versus Li/ Li + corresponds to the formation of SEI layers on the surface of Si active materials. 36 A sharp reduction peak around +0.1 V (vs. Li/Li + ) on the charging curve indicating the Li-alloying process, see eqn (3). Two anodic peaks appeared at 0.3 and 0.6 V in the anode branches of CV curves were attributed to the de-alloying process of Li x Si alloys, see eqn (4).…”

The effect of activated carbon and silicon oxycarbide as anode materials on lithium-ion battery

“…Numerous methods have been proposed to tackle these obstacles; in this matter, it involves using the mixture of silicon oxycarbide and activated carbon as anode materials. Si-based material is being regarded as a viable option to replace graphite in high-density LIBs due to its high theoretical capacity of 4200 mA h.g -1 , environmentally friendly character, and natural abundance of silicone [3]. However, Si is known to have low electric conductivity and huge volume variation of over 300% during lithiation and delithiation, thus impeding the success of Si-based anodes implementation in practical applications.…”

“…However, Si is known to have low electric conductivity and huge volume variation of over 300% during lithiation and delithiation, thus impeding the success of Si-based anodes implementation in practical applications. To overcome this issue, introducing a carbonaceous material, e.g., activated carbon, is expected to improve the Si-based anode performance by alleviating the volume change and mechanical stress, along with increasing its electronic properties [3].…”