A combined approach: Polyol synthesis of nanocrystalline Li2FeSiO4, doping multi-walled carbon nanotubes, and ionic liquid electrolyte to enhance cathode performance in Li-ion batteries. (20th December 2017)

• Record Type: Journal Article
• Authors: Thayumanasundaram, Savitha; Rangasamy, Vijay Shankar; Seo, Jin Won; Locquet, Jean-Pierre
• Is Part Of: Electrochimica acta. Volume 258(2017)
• Page Start: 1044
• Page End: 1052
• Publication Date: 2017-12-20
• Subjects: Polyol -- Silicate olivine -- Ionic liquid electrolyte -- MWCNT; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2017.11.156
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: Li2 MSiO4 (M – transition metal) is a promising class of materials for lithium-ion batteries due to the possibility of reversible extraction of two lithium ions per formula unit (theoretical capacity 333 mAh g −1 ). Here, we report a combined approach of synthesizing Li2 FeSiO4 (LFS) by polyol method and doping multi-walled carbon nanotubes (MWCNTs) to create an inter-particle conductive network. The prepared Li2 FeSiO4 is of orthorhombic phase (space group Pmn 21 ), with no substantial change on adding MWCNTs. An average particle size of 120 nm and the presence of an inter-particle conducting network are observed in the LFS-CNT sample. Electrochemical performance of the LFS materials was evaluated by assembling CR2032 coin cells with Li anode and 0.2 m BMPyTFSI-LiTFSI ionic liquid electrolyte at room temperature. Pure LFS delivered a discharge capacity of 165 mAh g −1 while LFS-CNT delivered 270 mAh g −1 at C/20 rate. LFS-CNT has a superior rate capability and a lower charge-transfer resistance (RCT = 10 Ω) than pure LFS (RCT = 53 Ω). The MWCNTs also serve as active lithium sites, significantly improving the Li + diffusion kinetics during cycling. Our results demonstrate that the polyol method enables particle size-reduction, and facilitates in-situ carbon-coating of individual particles to improve their electronic conduction.