US Patent 8663840 Encapsulated sulfur cathode for lithium ion battery

Methods of making a cathode element for an electrochemical cell. The methods comprise providing hollow carbon nanotubes and a sulfur source in a closed environment. Sulfur is deposited within an interior of the hollow carbon nanotube. The method includes cleaning an exterior surface of the carbon nanotubes and incorporating the carbon nanotubes into a cathode element. A cathodic material for a lithium-sulfur electrochemical cell is also provided. The material comprises a plurality of stacked-cone carbon nanotubes. Each nanotube defines a hollow interior and has a substantially continuous exterior surface area. Elemental sulfur is disposed within the hollow interior of each nanotube.