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Capillary Deposition of Binder-Free Lithium Sulfide-Carbon Composite in Three Dimensional Nickel Foam for High Performance Lithium-Sulfur Battery

Monday, 20 June 2016
Riverside Center (Hyatt Regency)
M. R. Kaiser (Institute for Superconducting and Electronic Materials), X. Liang, H. K. Liu, S. X. Dou, and J. Wang (University of Wollongong)
Lithium sulfide (Li2S), which has a theoretical capacity of 1166 mAh/g, is considered as a promising cathode material for the Li-S battery. The electrochemical performance of microsized Li2S is impaired, however, by its low electrical conductivity as well as first cycle high activation potential problem. In this work, microsized Li2S powder had been ball milled with different carbon sources to synthesize Li2S-C composites as well as to find the suitable carbon sources, which were then capillary-deposited in three-dimensional multi-layered Ni foam from a dioxolane-containing mixture to fabricate a binder-free Li2S-C composite cathode. A large amount of active material (~5 mg/cm2) was loaded in each cathode with the help of conventional capillary deposition method. Scanning electron micrographs show that the Li2S-C composite successfully fills the pores in the Ni foam through capillary action and maintains the integrity of the structure before and after cycling performance. High voltage (3.5V) 1st cycle charging was applied to activate the Li2S. Electrochemical performance testing shows that the capillary-deposited binder-free Li2S-C composite was successfully activated and showed excellent cycling performance along with superior rate capability. For further improvement of electrochemical performance, a single-walled carbon nanotube free-standing layer was inserted in between the cathode and the separator which inhibited longer chain polysulfide to travel from cathode to anode and minimized shuttle phenomenon thus improved the discharge capacity and the capacity retention.