Because of high absorption rate of nanometer silica fume and lithium battery, nanometer silica fume can significantly improve capacity of lithium battery. Nanometer silica fume and graphite can become alternatives of nano toner as raw materials.
It is a lithium battery anode material. Silicon / graphite composite materials are prepared by mechanical milling method and the corresponding complexes are tested by charge-discharge. It is found that the best ratio of silicon and graphite is 1:9.
Si-C composite materials can effectively reduce the expansion of lithium-ion absorption by silicon powder. It can increase the affinity with the electrolyte at the same time. It can improve cycling performance. Nanometer silica fume made of silicon nanowires used in rechargeable lithium ion battery anode material, or coated graphite surface of the nanometer silica fume do rechargeable lithium ion battery anode material can be improved more than three times the electrical capacity of rechargeable lithium battery and charging and discharging the number of cycles. The experimental results show that the obtained materials with both the cycling performance than pure nano-silicon, but also has a high reversible capacity than graphite, and significantly improve the capacity of lithium.
When silicon powder and graphite mass ratio of 4:6, the faster capacity fading after 25 cycles capacity for 200mA.h the / g, and therefore can not be too complex in the silica fume content. If the silicon content resulting in graphite can not be well to silicon powder dispersed, increased opportunities for contact between the nano-silica fume, the occurrence of reunion, the coulombic efficiency and cycling performance will decline. Silicon powder and graphite mass ratio of 3:7, the reversible capacity after 25 cycles of the complex is greater than the quality of silicon and graphite than for the reversible capacity of 4:6, but attenuation or soon. The quality of the silicon powder and graphite ratio of 1:9 and 2:8, the cycle performance, and 1:9.
Nanometer silica fume price is much higher than the graphite, it is used in production practice, silicon and graphite ratio of 1:9 is more economical. Compared with pure graphite, the mass ratio of 1:9 complexes for the first time reversible capacity could be greatly improved, is more than twice that of graphite cycling performance.
As lithium-ion battery anode materials, silicon powder and metal powder materials have high specific capacity. The silicon theoretical capacity is 4200mA.h/g, prepared by mechanical milling of graphite / nano-silicon compound is used as the anode material of lithium-ion battery. The composite reflects the high lithium content and good cycle performance of graphite, the small volume effect of silicon storage features, experimental results obtained silicon/graphite mass ratio of 1:9. The electrochemical performance tests show that the cycling performance of composite materials is relatively pure silicon electrode has greatly improved and has a reversible capacity higher than the graphite, is expected to replace the graphite and become a new lithium-ion battery anode material.
As a lithium-ion battery cathode materials nanometer silica fume has a maximum theoretical capacity. It is much higher than the widely used carbon materials. But the biggest drawback of silica fume as lithium ion batteries is quickly decay capacity and poor cycle performance in lithium alloying process and the shedding of active material. To solve this problem, researchers make three materials of nano-silica fume, titanium nitride nano and nano-titanium carbide as a composite material. The experiments show that they have a stable cycle performance. TiN and TiC play a stabilizing structure role as inert components.Source:http://www.mhcmp.com
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