Effect of capping agents in tin nanoparticles on electrochemical cycling

Abstract

Tin particles that were prepared using three different capping agents, hydrobenzamide, citrate, and polyvinyl pyrrolidone (PVP) exhibited different particle sizes. The hydrobenzamide-capped Sn had the smallest particle size (∼50 nm) and uniform distribution while the citrate and PVP-capped Sn had particle sizes of ∼100 and ∼300 nm, respectively, with severe particle aggregation. However, there was no SnO2 or SnO detected on the particle surfaces. The cycling results using coin-type half cells confirmed that the hydrobenzamide-capped Sn had the highest charge capacity of 994 mAh/g between 1.5 and 0 V and the best capacity retention. In contrast, the citrate and PVP-capped Sn showed severe capacity decay. Further analysis using cycled electrodes showed that the hydrobenzamide-capped Sn showed the least particle agglomeration and growth, compared with the others. From Fourier transform magnitude (FT) of Sn LIII-edge energy dispersive X-ray analysis spectra, these facts could be supported by the strong coordination formed as a result of chemical bonding between the nitrogen of the hydrobenzamide capping agent effectively inhibiting the particle growth during cycling.