Fabrication of Current Collectors and Binder-Free Electrodes on Separators Used in Lithium-Ion Batteries

We report the fabrication of a composite electrode through the deposition of electrode materials directly onto a separator to avoid the use of a metallic current collector. In addition to being an active electrode material, this method employs only graphene as both a carbon additive and a binder. A major achievement is the elimination of heavy and inactive current collector, harmful solvents, and resistive binder. The deposition of the composite film electrode was applied through the filtrated dispersion of a redox active material and graphene through a separator (Celgard), which is commonly used in battery. The electronic conductivity of LiFePO4/Celgard electrodes was similar to 10 times higher than that of conventional electrodes spread onto an aluminum current collector. The electrochemical performances of LiFePO4/C (LFP) and Li4Ti5O12 (LTO) half-cells fabricated according to this process and a conventional method were compared. A clear improvement in the electrochemical performance for electrodes fabricated using the new method was observed, particularly at high C-rates. LiFePO4/Celgard electrodes deliver specific capacities of up to 125 mAh.g(electrode)(-1) corresponding to more than 6 times the gravimetric capacity of an LFP electrode coated on Al foil. A LiFePO4/Li4Ti5O12 full cell made using film electrodes deposited on a Celgard membrane shows stable specific capacities during the cycling at various C-rates and delivers a specific capacity of 106 mAh.g(electrode)(-1) at a C/10 rate.