Liwen Ji

Graphene Oxide as a Sulfur Immobilizer in High Performance Lithium/Sulfur Cells

The loss of sulfur cathode material as a result of polysulfide dissolution causes significant capacity fading in rechargeable lithium/sulfur cells. Here, we use a chemical approach to immobilize sulfur and lithium polysulfides via the reactive functional groups on graphene oxide. This approach enabled us to obtain a uniform and thin (around tens of nanometers) sulfur coating on graphene oxide sheets by a simple chemical reaction-deposition strategy and a subsequent low-temperature thermal treatment process. Strong interaction between graphene oxide and sulfur or polysulfides enabled us to demonstrate lithium/sulfur cells with a high reversible capacity of 950-1400 mA h g(-1), and stable cycling for more than 50 deep cycles at 0.1C (1C = 1675 mA g(-1)).

Multilayer nanoassembly of Sn-nanopillar arrays sandwiched between graphene layers for high-capacity lithium storage

Sn nanopillar arrays embedded between graphene sheets were assembled using a conventional film deposition and annealing process. The as-formed three-dimensional (3D) multilayered nanostructure was directly used as an anode material for rechargeable lithium-ion batteries without adding any polymer binder and carbon black. Electrochemical measurements showed very high reversible capacity and excellent cycling performance at a current density as high as 5 A g−1. These results demonstrated that nanocomposite materials with highly functional 1D and 2D components can be synthesized by employing conventional top-down manufacturing methods and self-assembly principles.