Abstract: The loss of sulfur cathode material as a result of polysulfide dissolution causes significant capacity fading in rechargeable lithium/sulfur cells. Embodiments of the invention use a chemical approach to immobilize sulfur and lithium polysulfides via the reactive functional groups on graphene oxide. This approach obtains a uniform and thin (˜tens of nanometers) sulfur coating on graphene oxide sheets by a chemical reaction-deposition strategy and a subsequent low temperature thermal treatment process. Strong interaction between graphene oxide and sulfur or polysulfides demonstrate lithium/sulfur cells with a high reversible capacity of 950-1400 mAh g?1, and stable cycling for more than 50 deep cycles at 0.1 C.

Abstract: The loss of sulfur cathode material as a result of polysulfide dissolution causes significant capacity fading in rechargeable lithium/sulfur cells. Embodiments of the invention use a chemical approach to immobilize sulfur and lithium polysulfides via the reactive functional groups on graphene oxide. This approach obtains a uniform and thin (˜tens of nanometers) sulfur coating on graphene oxide sheets by a chemical reaction-deposition strategy and a subsequent low temperature thermal treatment process. Strong interaction between graphene oxide and sulfur or polysulfides demonstrate lithium/sulfur cells with a high reversible capacity of 950-1400 mAh g?1, and stable cycling for more than 50 deep cycles at 0.1 C.

Abstract: Multilayer structures with alternating graphene and Si thin films were constructed by a repeated process of filtering liquid-phase exfoliated grapheme film and subsequent coating of amorphous Si film using plasma-enhanced chemical vapor deposition (PECVD) method. The multilayer-structure composite films, fabricated on copper current collectors, can be directly used as anodes for rechargeable lithium-ion batteries (LIBs) without the addition of polymer binders or conductive additives. Fabricated coin-type half cells based on the new anode materials easily achieved a capacity almost four times higher than the theoretical value of graphite even after 30 cycles. These cells also demonstrated improved capacity retention and enhanced rate capability during charge/discharge processes compared to those of pure Si film-based anodes.