Co2SiO4/SiO2/RGO nanosheets: Boosting the lithium storage capability of tetravalent Si by using highly-dispersed Co element. (20th August 2018)

• Record Type: Journal Article
• Authors: Zhao, Yiming; Zheng, Lihua; Wu, Hao; Chen, Huan; Su, Liwei; Wang, Lianbang; Wang, Yuanhao; Ren, Manman
• Is Part Of: Electrochimica acta. Volume 282(2018)
• Page Start: 609
• Page End: 617
• Publication Date: 2018-08-20
• Subjects: Cobalt silicate -- Energy storage -- Graphene -- Lithium-ion batteries -- Tetravalent silicon; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2018.06.077
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: Tetravalent Si materials (SiO2 and transition metal silicates) are receiving tremendous attentions for lithium storage, whereas a troublesome problem is how to improve the content of active Si. This work reports a novel method to boost their lithium storage capabilities by using highly-dispersed Co element in the form of nanofilm-like Co2 SiO4 /SiO2 powder on the surface of reduced graphene oxide (RGO) that promotes the electronic diffusion and accommodates the volume changes. As a result, the Co2 SiO4 /SiO2 /RGO exhibits over 20 times higher reversible capacity and better rate performance than the SiO2 /RGO counterpart. In comparison, the Co2 SiO4 /SiO2 /RGO shows the highest reversible capacity (1382 mAh g −1 at 500 mA g −1 ) and longest life span (500 cycles) in all known silicates-based materials and higher power/energy density than both of commercial graphite and Li4 Ti5 O12 materials. Ex-situ X-ray photoelectron spectra and electrochemical tests at different voltage windows are conducted to illustrate the reason for the significantly improved performances. It demonstrates that tetravalent Si is gradually activated to lower-valence form by highly-dispersed Co generated with cycling. This observation provides new evidence for the electrochemical catalytic mechanism in transition metal silicates for lithium storage. Graphical abstract: Image 1 Highlights: A new approach is used to awaken the lithium storage capability of tetravalent Si. Co2 SiO4 /SiO2 /RGO shows the best performance in all-known silicate-based materials. A working mechanism and the essential role of Co element therein is confirmed.