A Novel S-containing Composite Material For The Cathodes Of Rechargeable Lithium Batteries

It is an effective way to develop new active materials, with the high specific capacity, of cathodes for increasing the specific capacity in the lithium (ion) batteries. This study mainly focuses on a novel S-containing composite, which is developed in our group.A new composite material has been successfully synthesized by heating mixed powders of polyacrylonitrile and elemental sulfur in certain conditions. The measurement of electrochemical properties showed that it had initial reversible capacity of 660 mAh/g and kept 500mAh/g after 110 cycles, also good charge-discharge ability at -15 and 40.Based on the structure characterization by XRD, FTIR, BSE, TGA and ICP etc, it is preliminarily concluded that the synthetic material is a composite, composed of organo polysulfides and elemental sulfur. In this organo polysulfides, the polysulfide bonds link on the conductive polymer. The residual elemental sulfur is embedded in the network of the organo polysulfides. Based on this structure, the charge-discharge process and mechanism are discussed. Those two kind of existence for sulfur can depress the dissolution of sulfur and its electrochemical reaction product, which can much improve the cycleability of the cathode.The polymer electrolyte was prepared by a phase-separation technique. It avoids the disadvantage of Bellcore technique, which asks for more complicated operation. The polymer battery, composed of S-containing composite, polymer electrolyte, both above mentioned, and lithium foil were assembled and the charge-discharge capacity, cycle life and self-discharge property were systematically studiedFor scaling up, the reaction synthesis with larger amount of reagents was examined and discussed.