EFFECT OF PREPARATION METHOD OF SULFUR-MWNT COMPOSITE ELECTRODE ON ELECTROCHEMICAL PROPERTIES OF Li/S BATTERY

摘要

Lithium-ion battery (LIB) is recognized as a widely used power source for portable electronic devices, in which carbon and lithium metal oxides were used for anode and cathode, respectively. However, the development of electronic devices and ecological transportations like electric vehicle (EV) has triggered extensive studies to replace conventional costly materials with new materials with higher energy densities, but lower price than current LIBs. One that meets the requirements of new battery materials for cathode is the elemental sulfur. It has high theoretical capacity of 1675 mAh g~(-1) assuming the complete reaction of sulfur with lithium to form Li_2S and theoretic specific energy of 2600 Wh kg~(-1). Though its use for cathode is advantageous in terms of energy densities, there are some problems for realization of lithium-sulfur batteries such as the insulating nature of sulfur and sulfur products and the dissolution of polysulfides which are generated during sulfur reduction. These cause long cycling failure and capacity fading, etc. Recently performed research efforts have been oriented to addition of conductive agents, i.e. carbon in sulfur electrodes to increase the conductivity of sulfur electrodes and the utilization of active material as well as to absorb polysulfides. Multi-walled carbon nanotube (MWNT) is attractive because it provides superior electronically conductive network to conventional carbon black and acetylene black effectively. Thus, the elemental sulfur and MWNT composite (S-MWNT) would be a good choice to development of Li/S batteries.