Carbon black/graphene-modified aluminum foil cathode current collectors for lithium ion batteries with enhanced electrochemical performances

摘要

Though aluminum foils are widely applied as cathode current collectors for lithium ion batteries, they still face many challenges, such as the limited contact area, weak adhesion with electrode materials and localized corrosion by electrolytes during long-term cycling, which will lead to the degradation of electrochemical performances. Here, graphene-modified aluminum foils and carbon black/graphene modified aluminum foils are prepared as the current collectors for lithium iron phosphate lithium ion batteries by a facile solution coating method. We find that the batteries fabricated with carbon black/graphene-modified aluminum foils exhibit largely improved electrochemical performances in rate capability, internal resistance and long-term cycling capacity retention, compared with the bare aluminum and graphene-modified aluminum foils. This work reveals the coatings of graphene nanosheets not only can increase the contact area and enhance the adhesion between electrode materials and current collectors, which is beneficial for their electrical contact and charge transport, but also can suppress the aluminum foil corrosion during long-term cycling. Meanwhile, the excessive coverage of graphene nanosheets will lower the battery performances due to the interlayer contact increment of graphene nanosheets. In addition, carbon black combines graphene to form a co-conductive network effectively compensating the low interlayer electrical conductivity of graphene nanosheets.