Xianwei Guo

Mechanism of Lithium Storage in MoS2 and the Feasibility of Using Li2S/Mo Nanocomposites as Cathode Materials for Lithium–Sulfur Batteries

The most-popular strategy to improve the cycling stability and rate performance of the sulfur electrode in lithium-sulfur (Li-S) batteries is to astrict the sulfur in a conducting medium by using complicated chemical/physical processing. Lithium sulfide (Li(2)S) has been proposed as an alternative electrode material to sulfur. However, for its application, it must meet challenges such as high instability in air together with all of the drawbacks of a sulfur-containing electrode. Herein, we report the feasibility of using Li(2)S, which was obtained by electrochemical conversion of commercial molybdenum disulfide (MoS(2)) into Li(2)S and metallic molybdenium (Mo) at low voltages, as a high-performance active material in Li-S batteries. Metallic Mo prevented the dissolution of lithium polysulfides into the electrolyte and enhanced the conductivity of the sulfide electrode. Therefore, the in situ electrochemically prepared Li(2)S/Mo composite exhibited both high cycling stability and high sulfur utilization.

Polypyrrole-iron-oxygen coordination complex as high performance lithium storage material

Current lithium ion battery (LIB) technologies are all based on inorganic electrodes though organic materials have been hyped as electrodes for years. Disadvantages such as low specific capacity and poor rate performance hinder their applications. Here we report a novel high-performance organometallic lithium-storage material, a polypyrrole-iron-oxygen (PPy-Fe-O) coordination complex. Extended X-ray absorption fine structure (EXAFS) spectroscopy and density functional theory (DFT) calculations indicate that this complex has a multilayer structure. The strong and stable intralayer Fe–N coordination permits the material to possess high specific capacity, the high reversibility of its interlayer Fe–O–Fe interaction during cycling ensures its high cycling stability and the conducting PPy matrix endows it with outstanding rate performance. These findings pave the way to constructing a new type of high-performance organic anode materials for LIBs.