Carbon-sulfur composites as the cathode of rechargeable Li-S batteries have shown outstanding electrochemical performance for high power devices. Here, we report the promising electrochemical charge-discharge properti...Carbon-sulfur composites as the cathode of rechargeable Li-S batteries have shown outstanding electrochemical performance for high power devices. Here, we report the promising electrochemical charge-discharge properties of a carbon-sulfur composite, in which sulfur is impregnated in porous hollow carbon spheres （PHCSs） via a melt-diffusion method. Instrumental analysis shows that the PHCSs, which were prepared by a facile template strategy, are characterized by high specific surface area （1520 m2.g 1）, large pore volume （2.61 cm^3·g^-1）, broad pore size distribution from micropores to mesopores, and high electronic conductivity （2.22 S·cm-1）. The carbon-sulfur composite with a sulfur content of 50.2 wt.% displays an initial discharge capacity of 1450 mA.h·g^-1 （which is 86.6% of the theoretical specific capacity） and a reversible discharge capacity of 1357 mA.h·g^-1 after 50 cycles at 0.05 C charge-discharge rate. At a higher rate of 0.5 C, the capacity stabilized at around 800 mA-h·g^-1 after 30 cycles. The results illustrate that the porous carbon-sulfur composites with hierarchically porous structure have potential application as the cathode of Li-S batteries because of their effective improvement of the electronic conductivity, the repression of the volume expansion, and the reduction of the shuttling loss.展开更多
A facile synthesis of the hierarchically porous cathode with Mo2C nanoparticles through the electrospinning technique and heat treatment is proposed. The carbonization temperature of the precursors is the key factor f...A facile synthesis of the hierarchically porous cathode with Mo2C nanoparticles through the electrospinning technique and heat treatment is proposed. The carbonization temperature of the precursors is the key factor for the formation of M02C nanoparticles on the carbon nanofibers （MCNFs）. Compared with the Mo2N nanoparticles embedded into N-doped carbon nanofibers film （MNNFs） and N-doped carbon nanofibers film （NFs）, the battery with MCNFs cathode is capable of operation with a high-capacity （10,509 mAhg-1 at 100 mAg-l）, a much reduced discharge-charge voltage gap, and a long-term life （124 cycles at 200 mA g-1 with a specific capacity limit of 500 mAh g -1）. These excellent performances are derived from the synergy of the following advantageous factors： （1） the hierarchically self-standing and binder-free structure of MCNFs could ensure the high diffusion flux of Li＋ and O2 as well as avoid clogging of the discharge product, bulk Li202; （2） the well dispersed M02C nanoparticles not only afford rich active sites, but also facilitate the electronic transfer for catalysis.展开更多
文摘Carbon-sulfur composites as the cathode of rechargeable Li-S batteries have shown outstanding electrochemical performance for high power devices. Here, we report the promising electrochemical charge-discharge properties of a carbon-sulfur composite, in which sulfur is impregnated in porous hollow carbon spheres （PHCSs） via a melt-diffusion method. Instrumental analysis shows that the PHCSs, which were prepared by a facile template strategy, are characterized by high specific surface area （1520 m2.g 1）, large pore volume （2.61 cm^3·g^-1）, broad pore size distribution from micropores to mesopores, and high electronic conductivity （2.22 S·cm-1）. The carbon-sulfur composite with a sulfur content of 50.2 wt.% displays an initial discharge capacity of 1450 mA.h·g^-1 （which is 86.6% of the theoretical specific capacity） and a reversible discharge capacity of 1357 mA.h·g^-1 after 50 cycles at 0.05 C charge-discharge rate. At a higher rate of 0.5 C, the capacity stabilized at around 800 mA-h·g^-1 after 30 cycles. The results illustrate that the porous carbon-sulfur composites with hierarchically porous structure have potential application as the cathode of Li-S batteries because of their effective improvement of the electronic conductivity, the repression of the volume expansion, and the reduction of the shuttling loss.
基金supported by the National Key Research and Development Program of China(2017YFA0206704 and 2016YFB0100103)the National Basic Research Program of China(2014CB932300)+3 种基金Strategic Priority Research Program of the Chinese Academy of Sciences(XDA09010404)Technology and Industry for National Defence of China(JCKY2016130B010)the National Natural Science Foundation of China(51771177,21422108,51472209,and 51472232)Jilin Province Science and Technology Development Program(20160101289JC)
文摘A facile synthesis of the hierarchically porous cathode with Mo2C nanoparticles through the electrospinning technique and heat treatment is proposed. The carbonization temperature of the precursors is the key factor for the formation of M02C nanoparticles on the carbon nanofibers （MCNFs）. Compared with the Mo2N nanoparticles embedded into N-doped carbon nanofibers film （MNNFs） and N-doped carbon nanofibers film （NFs）, the battery with MCNFs cathode is capable of operation with a high-capacity （10,509 mAhg-1 at 100 mAg-l）, a much reduced discharge-charge voltage gap, and a long-term life （124 cycles at 200 mA g-1 with a specific capacity limit of 500 mAh g -1）. These excellent performances are derived from the synergy of the following advantageous factors： （1） the hierarchically self-standing and binder-free structure of MCNFs could ensure the high diffusion flux of Li＋ and O2 as well as avoid clogging of the discharge product, bulk Li202; （2） the well dispersed M02C nanoparticles not only afford rich active sites, but also facilitate the electronic transfer for catalysis.
