Composite Graphene‐Modified Aluminum Foil Cathode Current Collectors for Lithium‐ion Battery with Enhanced Mechanical and Electrochemical Performances

Aluminum foil is a typical cathode collector in lithium-ion batteries,  it encounters various issues, including restricted contact with the active substance, poor adhesion, and regional corrosion associated with the electrolyte. Although conventional carbon-coated aluminum foils partially alleviate such problems, they suffer from excess weight and thickness of their carbon layers. Here a simple casting method to prepare Ketjen Black/aqueous graphene dispersion slurry modified aluminum foil (KB-AGD-Al-CCs) and graphene micro-sheets/aqueous graphene dispersion slurry modified aluminum foil (GM-AGD-Al-CCs). Our results indicate that batteries utilizing graphene-modified aluminum foils exhibited superior electrochemical performance compared with that of carbon-coated aluminum foils. The lithium-ion battery employing GM-AGD-Al-CCs as cathode current collectors exhibits reversible specific capacities of 155, 118, and 92.5 mAh/g at current densities of 0.1, 5, and 10 C. After cycling for 1800 cycles at 5 and 10 C, its specific capacities remain at 91 and 77.5 mAh/g. Combing contact angle measurement, electrical conductivity test with electrochemical impedance spectroscopy indicates that the graphene coating decreases the contact angle between the commercial LiFePO4 and current collector, increases the electrical conductivity of the electrode and adhesion. Moreover, the inclusion of GM and KB as conductive additives compensates for graphene's low interlayer conductivity by forming a conductive network.