Xuelin Yang

High-Performance Silicon/Carbon/Graphite Composites as Anode Materials for Lithium Ion Batteries

Silicon/carbon and silicon/carbon/graphite composites have been synthesized at room temperature using concentrated H 2 SO 4 as a dehydration agent. As a ductile matrix, the novel amorphous carbon obtained from the dehydration process could effectively buffer the volume change of silicon particles during discharge-charge cycling. The introduction of graphite in the silicon/carbon composite further improved the cycling performance. The composite with 30 wt % of amorphous carbon replaced by graphite demonstrated a stable capacity of 712.8 mAh g -1 and a high capacity retention ratio of 84.1% at 0.1 C over 50 cycles, suggesting it is a favorable candidate as anode material for lithium-ion batteries.

Synthesis and the improved high-rate performance of LiMn2O4/Ag composite cathode for lithium-ion batteries

The LiMn 2 O 4 /Ag composite has been prepared by a chemical deposition of silver particles. Well dispersed and nanosized silver particles in the composites were realized by careful control of the preparation conditions. The experimental results showed that the 6.3 wt % Ag in the composite obviously reduced the impedance of the precursor and the polarization of the cathode/electrolyte interface in the cell and effectively improved the high rate cycling performance of LiMn 2 O 4 . The reversible capacity after 50 cycles remained at 103.2 mAh/g with capacity loss of 10.57% compared to the first cycle even at the charge-discharge rate as high as 10C.

Study on the Li + Insertion/Extraction for Silicon Nanosized Silver Composite Electrode

Nanosized silver particle (<10 nm) was highly dispersed on the surface of silicon particle by electroless deposition on the basis of a stirred silver mirror reaction. Ex situ X-ray diffraction and discharge/charge cycling measurements indicated that silver, as well as silicon, participated in the insertion/extraction process of Li + and played a positive role in the complete extraction of Li + from silicon host. Furthermore, ordered structure of silicon can be obtained after the extraction of Li + with the help of silver additives, which indicates the effect of silver additives in promoting the recrystallization of amorphous Li + -extracted silicon.