title: Effect of Phosphorus-Doping on Electrochemical Performance of Silicon Negative Electrodes in Lithium-Ion Batteries.
abstract: The effect of phosphorus (P)-doping on the electrochemical performance of Si negative electrodes in lithium-ion batteries was investigated. Field-emission scanning electron microscopy was used to observe changes in surface morphology. Surface crystallinity and the phase transition of Si negative electrodes before and after a charge-discharge cycle were investigated by Raman spectroscopy and X-ray diffraction. Li insertion energy into Si was also calculated based on computational chemistry. The results showed that a low P concentration of 124 ppm has a meaningful influence on the electrochemical properties of a Si negative electrode; the cycle performance is improved by P-doping of Si. P-doping suppresses the changes in the surface morphology of a Si negative electrode and the phase transition during a charge-discharge cycle. Li insertion energy increases with an increase in the P concentration; Li insertion into P-doped Si is energetically unfavorable, which indicates that the crystal lattice of Si shrinks as a result of the replacement of some Si atoms with smaller P atoms, and therefore, it is more difficult to insert Li into P-doped Si. These results reveal that suppression of the phase transition reduces the large change in the volume of Si and prevents a Si negative electrode from disintegrating, which helps to improve the otherwise poor cycle performance of a Si electrode.
authors.affiliation: Department of Chemistry and Biotechnology, Graduate School of Engineering, and ‡Center for Research on Green Sustainable Chemistry, Tottori University , 4-101 minami, Koyama-cho, Tottori 680-8552, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Domi
authors.affiliation: Department of Chemistry and Biotechnology, Graduate School of Engineering, and ‡Center for Research on Green Sustainable Chemistry, Tottori University , 4-101 minami, Koyama-cho, Tottori 680-8552, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Usui
authors.affiliation: Department of Chemistry and Biotechnology, Graduate School of Engineering, and ‡Center for Research on Green Sustainable Chemistry, Tottori University , 4-101 minami, Koyama-cho, Tottori 680-8552, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Shimizu
authors.affiliation: Department of Chemistry and Biotechnology, Graduate School of Engineering, and ‡Center for Research on Green Sustainable Chemistry, Tottori University , 4-101 minami, Koyama-cho, Tottori 680-8552, Japan.
authors.forename: Yuta
authors.initials: Y
authors.lastname: Kakimoto
authors.affiliation: Department of Chemistry and Biotechnology, Graduate School of Engineering, and ‡Center for Research on Green Sustainable Chemistry, Tottori University , 4-101 minami, Koyama-cho, Tottori 680-8552, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Sakaguchi
keywords: and phase transition; crystallinity; lithium-ion battery; morphology; negative electrode; phosphorus doping; silicon