Effect of a Surfactant Assisted Synthesis on the Electrochemical Performance of a LiFePO4- CNT Composite Electrode

Ulla Lassi ； Tao Hu ； Elina Pohjalainen ； Tanja Kallio ； Krisztian Kordas ； Heli Jantunen

《International Journal of Material Science》 4卷1期 (2014/03) Pp. 1-7

https://doi.org/10.14355/ijmsci.2014.0401.01

並列摘要

This research aims at improving the performance of lithium iron phosphate (LiFePO_4) positive electrode material by using carbon nanotubes (CNT) to increase the conductivity and nonionic surfactant to achieve better dispersion of CNTs in the composite material. LiFePO_4-CNT composites were synthesized by the wet chemical method and functionalized multi-walled carbon nanotubes MWCNT-COOH were added in-situ. The nonionic surfactant polyoxyethyleneoleyl ether (E-230) was used to enhance the dispersion of MWCNT in the LiFePO_4nanopowder and removed during the last step of the synthesis to avoid possible unwanted side reactions of the surfactants in the battery. During this last step, the composite materials were heated at 500-700°C in an Ar-H_2 atmosphere for several hours. XRD, DTA/TG, FESEM and EFTEM were used for characterization of the crystallization and microstructure of the obtained composites. Electrochemical performance was characterized by charging and discharging experiments with various Crates using standard lithium ion battery half cells. Results showed that the addition of MWCNT-COOH and the surfactant E-230 remarkably increased the obtained capacities of LiFePO_4. Acting as a dispersant and interfacial coupling agent, the nonionic surfactant enhanced the dispersion of carboxylic MWCNT into the LiFePO_4 during the in-situ synthesis and enhanced the specific capacity of the tested composites.

並列關鍵字

Lithium-ion Battery ； Lithium Iron Phosphate ； Carbon Nanotube ； LiFePO_4-MWCNTComposite ； In-situ Synthesis ； Charge/ Discharge ； Electrochemical Performance