1 research outputs found
Effect of Phosphorus-Doping on Electrochemical Performance of Silicon Negative Electrodes in Lithium-Ion Batteries
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