Scalable synthesis of a porous structure silicon/carbon composite decorated with copper as an anode for lithium ion batteries

Silicon is an advanced anode material for lithium-ion batteries due to its ultra-high theoretical capacity. However, its commercial application is limited by the enormous volume change and low electrical conductivity. Herein, we synthesize a copper-doped silicon/carbon porous composite that can effectively solve the current dilemma. Uniform anchoring of copper particles on silicon significantly improves the electronic conductivity of composites. By adjusting the content of copper, the initial coulombic efficiency is increased substantially from 60.7 % to 87.6 %. The effect of porosity on the electrochemical properties is systematically studied. The optimized Si/Cu/void@C-14 anode exhibits excellent rate capability (529.3 mAh g-1 at 2 C) and cycle stability (1076.2 mAh g-1 after 300 cycles). The reasons are that the Li+ diffusion coefficient is increased effectively to 3.32 x 10-10-2.54 x 10-9 cm2 s-1, and the volume expansion rate is reduced vastly to 8.8 %. In addition, the full cells coupling LiNi0.8Co0.1Mn0.1O2cathode with perlithiated Si/Cu/void@C-14 anode provide a high energy density of 491.5 Wh kg-1 after 100 cycles. It is worth noting that the Si/Cu/void@C-14 composite is synthesized with low-cost raw materials through facile and scalable processes, revealing that the composites have promising potential as high capacity anode materials in a commercial application.

Automated summary

The authors synthesized a copper-doped silicon/carbon porous composite, which significantly improved the electronic conductivity of the material. By adjusting the copper content, the initial coulombic efficiency was greatly increased. The optimized anode exhibited excellent rate capability and cycle stability, indicating its potential for commercial application.