title: Binder free three-dimensional sulphur/few-layer graphene foam cathode with enhanced high-rate capability for rechargeable lithium sulphur batteries.
abstract: A novel ultra-lightweight three-dimensional (3-D) cathode system for lithium sulphur (Li-S) batteries has been synthesised by loading sulphur on to an interconnected 3-D network of few-layered graphene (FLG) via a sulphur solution infiltration method. A free-standing FLG monolithic network foam was formed as a negative of a Ni metallic foam template by CVD followed by etching away of Ni. The FLG foam offers excellent electrical conductivity, an appropriate hierarchical pore structure for containing the electro-active sulphur and facilitates rapid electron/ion transport. This cathode system does not require any additional binding agents, conductive additives or a separate metallic current collector thus decreasing the weight of the cathode by typically ∼20-30 wt%. A Li-S battery with the sulphur-FLG foam cathode shows good electrochemical stability and high rate discharge capacity retention for up to 400 discharge/charge cycles at a high current density of 3200 mA g(-1). Even after 400 cycles the capacity decay is only ∼0.064% per cycle relative to the early (e.g. the 5th cycle) discharge capacity, while yielding an average columbic efficiency of ∼96.2%. Our results indicate the potential suitability of graphene foam for efficient, ultra-light and high-performance batteries.
authors.affiliation: Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, CB2 3QZ, UK. rvk10@cam.ac.uk.
authors.forename: Kai
authors.initials: K
authors.lastname: Xi
authors.forename: Piran R
authors.initials: PR
authors.lastname: Kidambi
authors.forename: Renjie
authors.initials: R
authors.lastname: Chen
authors.forename: Chenlong
authors.initials: C
authors.lastname: Gao
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Peng
authors.forename: Caterina
authors.initials: C
authors.lastname: Ducati
authors.forename: Stephan
authors.initials: S
authors.lastname: Hofmann
authors.forename: R Vasant
authors.initials: RV
authors.lastname: Kumar