Lithium-sulfur batteries display winning qualities, such as low production cost, environmental friendliness, and high energy density. Researchers usually give up, or look elsewhere, when the materials’ poor cycle life and loss of active materials on both anode and cathode show up. Researchers at Beihang University in Beijing report developing “a new Li-sulfur battery using honeycomb-like sulfur copolymer uniformly distributed onto 3D graphene (3D cpS-G) networks for a cathode material and a 3D lithiated Si-G network as anode.” They report “a high reversible capacity of 620 milli-Amp hours per gram, [and an] ultrahigh energy density of 1,147 Watt-hours per kilogram (based on the total mass of cathode and anode), good high-rate capability and excellent cycle performance over 500 cycles (0.028% capacity loss per cycle).” The materials used in the cathode and anode presented challenges. The “inherent insulation of sulfur” on the cathode and the high solubility of polysulfide intermediates cause an inability of the active materials to respond to one another, …
Vanadium Oxide/Lithium Batteries Offer Promise of High Power, Long Life
Henry Ford once brought a French metallurgist to Detroit, part of his plan to build cars with lighter, stronger steel. Vanadium, which the French used in their automobiles, offered him the chance to make the Model T lighter and stronger, and its part in the car’s alloyed steel gave the Model T the longevity which followed it through one of the longest production runs in history. Now battery researchers are looking at another quality of this mineral, its ability to form a superior cathode for batteries that “could supply both high energy density and significant power density. Combined with graphene, the wonder material du jour, vanadium oxide (VO2) could couple longevity echoing the Model T’s with charge and discharge rapidity similar to a supercapacitors. Materials scientist Pulickel Ajayan at Rice University created ribbons of vanadium oxide (VO2) thousands of times thinner than a sheet of paper, and combined those with atom-thick ribbons of graphene to form cathodes which were built …