Effects of composition and structure on the performance of tin/graphene-containing carbon nanofibers for Li-ion anodes. Issue 25 (8th March 2017)

• Record Type: Journal Article
• Authors: Dufficy, Martin K.; Huang, Sheng-Yang; Khan, Saad A.; Fedkiw, Peter S.
• Is Part Of: RSC advances. Volume 7:Issue 25(2017)
• Page Start: 15428
• Page End: 15438
• Publication Date: 2017-03-08
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c6ra26371b
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : We use structure–composition relationships to engineer tin-containing nanofibers for Li-ion anodes that retain their capacities over 900 cycles. Abstract : Tin is a promising replacement for graphite anodes in Li-ion batteries (994 mA h g −1 for Sn vs. 372 mA h g −1 for graphite), but suffers from particle pulverization upon lithiation that causes capacity fade. Herein, thermally reduced graphene oxide-containing carbon nanofibers (TRGO/CNFs) are used as scaffolds to house Sn/SnO2 particles, enhance anode capacity beyond that of graphite, and prolong cycle life of Sn-based electrodes. This study attempts to elucidate structure–composition relationships of tin-TRGO/CNF electrodes that lead to increased capacity retention. The composition and morphology of tin-TRGO/CNFs are assessed as a function of heat-treatment temperature and Sn loading as a means to understand and correlate electrochemical performance with physical features. We find: (1) the oxidation state of tin in TRGO/CNFs is in part determined by temperature-dependent, thermal-decomposition products of polyacrylonitrile-derived CNFs, and (2) precursor Sn(iv ) loadings ≤10 wt% in the tin-TRGO/CNFs lead to Sn(0) or SnO2 particles embedded within the fiber + TRGO matrix. Electrodes with precursor Sn(iv ) loading ≤10 wt% have smaller tin particles than electrodes with Sn(iv ) loadings >10 wt%, and have longer cycle-lives; reversible capacities of ∼600 mA h g −1 are observed at 0.2C rates, while capacities of ∼400 mA h g −1 are observed after hundreds of cycles at 2C rates. The durable graphene-containing nanofiber matrix, coupled with the high-capacity of tin, provides a promising anode material for Li-ion cells.