Initiating Fluorine Chemistry in Polycyclic Aromatic Hydrocarbon-Derived Carbon for New Cluster-Mode Na Storage with Superhigh Capacity.

Carbon materials are widely accepted as promising candidates for sodium-ion batteries (SIBs) anodes due to their chemical stability and conductivity, while the capacity is still unsatisfactory. Here, this work reports the superhigh capacity Na storage through initiating fluorine chemistry (CF bonds) in carbon synthesized by the dehydrogenation and fluorination of polycyclic aromatic hydrocarbon such as pitch. Experimental and theoretical investigations uncover that CF bonds exist at the form of dangling bonds (CF x ), which generates the coexistence of graphitic and defective nanodomains. It delivers a superhigh capacity of 450 mAh g -1 , far surpassing most of current SIBs carbon anodes. Theoretical calculation attributes this performance to a new Na storage mechanism that Na can be accommodated in the form of cluster rather than a single ion at each host site with F-doping. This work highlights the significance of carbon material chemistry in establishing the novel ion storage manner in SIBs and other batteries.