Electrospray synthesis of nano-Si encapsulated in graphite/carbon microplates as robust anodes for high performance lithium-ion batteries

Abstract

Developing efficient Si-based anode materials for new-generation lithium-ion batteries (LIBs) has drawn extensive attention. Here, an electrosprayed Si/graphite/carbon (Si/G/C) composite is explored as a prominent anode material for LIBs. The designed Si/G/C composite possesses a reasonable structure with nano-Si encapsulated in the conductive graphite flake/amorphous carbon framework. The Si/G/C composite achieves superior reversible Li⁺ storage capability, showing a considerable discharge capacity of 832 mA h g⁻¹ at 200 mA g⁻¹. Moreover, it realizes an encouraging capacity of ca. 400 mA h g⁻¹ under a high current density of 500 mA g⁻¹ after 200 cycles. The excellent capacity and rate performance can be attributed to the structural benefits of the Si/G/C composite: (i) the highly conductive graphite flakes serve as good dispersive scaffolds and electronic conductors, allowing for fast charge transfer and favorable ion diffusion; (ii) the amorphous carbon layer acts as a protective coating to bind/fix nano-Si onto graphite and reduce the formation of unstable solid electrolyte interphase (SEI) film; and (iii) both the layered graphite and amorphous carbon layer introduce adequate buffer space or voids to alleviate the volume changes of Si during the Li⁺ insertion/extraction cycles. This high-capacitive and robust Si/graphite-based hybrid is attractive as an alternative anode material for practical rechargeable LIBs.