Understanding the Sn Loading Impact on the Performance of Mesoporous Carbon/Sn-Based Nanocomposites in Li-Ion Batteries

Herein, we report a systematic study on the understanding of the influence of tin metal precursor salt amount on the formation of carbon/tin hybrid materials and their performances as anode in Li-ion batteries. Small Sn metallic particles (≈ 5 nm) covered by a SnO2 layer were uniformly dispersed in a mesoporous carbon for low loading of tin, while for higher Sn loading the formation of Sn-based particles aggregates (~200 nm) is promoted as well. By increasing the Sn loading from 20 to 80%, the irreversible capacity was successfully reduced and the reversible capacity improved. This could be mainly related to the decrease of the C/Sn hybrids specific surface area and the increase of the Sn active species. For long term cycling, capacity fading was observed particularly for high Sn loadings and assigned to the Sn nanoparticles placed outside the carbon network which upon lithiation witness large volume expansion leading to severe particle growth and agglomeration. Therefore, similar reversible capacities at long cycling are reached no matter the Sn loading. For optimal electrochemical performances, it appears that a balance between the amount of Sn and uniform small Sn-based particles dispersion within carbon matrix must be assured in order to design high performance anode for Li-ion batteries.