Journal of Power Sources, Vol.405, 51-60, 2018
Synergistic stabilizing lithium sulfur battery via nanocoating polypyrrole on cobalt sulfide nanobox
Design and assembly of nanostructure are devoted to improving electrochemical properties of lithium sulfur battery by virtue of synergetic protective effect. Meanwhile, electrode materials are also particularly important for achieving good cycling stability and capability. Herein, we integrate CoS nanobox and conductive polypyrrole to boost cycle and rate performance based on synergy of physical encapsulating and chemical trapping. Benefiting from the superiority of ZIF-67 template and ion exchange strategy, the CoS nanobox possesses large interspace and porous structure, which effectively buffers volume change of electrode and generates adequate anchoring sites infiltrated by electrolyte. Polypyrrole layer can further inhibit polysulfide shuttling and accelerate electronic conductivity. The CoS@PPy as host presents low overpotential and fast kinetics. As a result, the CoS@PPy/S electrode with a sulfur content of 60% as a desirable candidate exhibits good sulfur utilization (initial discharge capacity of 1165 mAh g(-1) at 0.2 degrees C) and a capacity retention of above 80% with a capacity fading rate of 0.10% per cycle after 200 cycles at 0.5 degrees C. The design philosophy and fabricating technique of composite electrode with unique architectures can be further extended to assemble various metal compounds and conductive polymer for developing rechargeable batteries with high density energy storage.
Keywords:Cobalt sulfide nanoboxes;Polypyrrole nanocoating;Heterostructure;Sulfur hosts;Lithium sulfur battery