Electrochemical Characterization of Cu-Catalysed Si Nanowires as an Anode for Lithium-Ion Cells

P P Prosini,V Orsetti,M Moreno,F Rondino,A Santoni,L Pilloni,A Rufoloni,C Cento,M Ottaviani

doi:10.1155/2020/4272090

Abstract

Silicon (Si) nanowires (NWs) grown on stainless-steel substrates by Cu-catalysed Chemical Vapour Deposition (CVD) have been prepared to be used as anodes in lithium-ion batteries. The use of NWs can overcome the problems related to the Si volume changes occurring during lithium alloying by reducing stress relaxation and preventing material fragmentation. Moreover, since the SiNWs are grown directly on the substrate, which also acts as a current collector, an excellent electrical contact is generated between the two materials without the necessity to use additional binders or conducting additives. The electrochemical performance of the SiNWs was tested in cells using lithium metal as the anode. A large irreversible capacity was observed during the first cycle and, to a lesser extent, during the second cycle. All the subsequent cycles showed good reversibility even if the coulombic efficiency did not exceed 95%, suggesting the formation of an unstable SEI film and a continuous decomposition of the electrolyte on the silicon surface. The absence of a stable SEI film was assumed responsible for a linear capacity fade observed upon cycling. On the other hand, the electrochemical characterization performed at different values of the charging current showed that SiNWs possess an exceptionally high rate capability.

Highlights

Rechargeable lithium-ion batteries (LIBs) are considered as one of the most versatile storage systems to power consumer electric devices, electric vehicles, and stationary energy storage systems due to their high energy density, long cycle life, and high-power performance [1, 2]
We report about the Chemical Vapour Deposition (CVD) synthesis on stainless steel of Cu-catalysed SiNWs with a well-defined morphology and core-shell structure
When the growth temperature was set to values above 700°C, the SEM images clearly showed the absence of SiNW and the presence of a layer of silicon covering the entire surface of the stainless steel

Summary

Introduction

Rechargeable lithium-ion batteries (LIBs) are considered as one of the most versatile storage systems to power consumer electric devices, electric vehicles, and stationary energy storage systems due to their high energy density, long cycle life, and high-power performance [1, 2]. Polymeric coating has been widely investigated due to the evident improvement of the electrical conductivity of the Si-based anode and to the better capability of accepting the volume change during the charge-discharge processes [26, 27] As a result, this kind of anode exhibits an excellent long-term cycling ability with capacity retention of 83.4%. Among 1D nanostructures, SiNWs have attracted much attention due to the large specific surface area, short diffusion path, and reduced internal stress and, especially, because they have a high cracking strength that can improve their electrochemical performance in terms of capacity retention [29] They can be grown directly on the current collector eliminating the need for binders or conductive materials. Long-term cycling was considered unsuitable for practical applications

Experimental

Results and Discussion

Conclusions