Nano-silicon @ soft carbon embedded in graphene scaffold: High-performance 3D free-standing anode for lithium-ion batteries

Abstract

Herein, the three-dimensional free-standing nano-silicon @ soft carbon embedded in graphene scaffold composite is prepared to boost the lithium storage property of the silicon anode. For the aspect of “single”, the own volume expansion is relieved by the encapsulated soft carbon layer and the soft carbon layer can suppress the repeated formation of solid electrolyte interface films onto the “single” silicon nanoparticle (SNP). Moreover, the soft carbon layer possesses alternating amorphous and crystalline regions to provide the rapid lithium-ion diffusion channel. On the side of “monolithic”, the 3D free-standing graphene-scaffold loading with evenly distributed SNPs eliminates collisions between SNPs during the charging/discharging cycles, and endows the ‘monolithic’ electrode with excellent electronic conductivity, fast lithium-ion diffusion pathway and high SNPs content. Thus, the above composite anode exhibits superior specific capacity, cycling performance and rate performance, such as around 2600 mA h g−1 (8.34 mA h cm−2) of specific capacity at a current density of 0.2 A/g and almost no capacity attenuation after 100 cycles. The design thinking (from ‘single’ to ‘monolithic’) paves a new avenue towards high-performance anodes of silicon and transition metal oxides.