Interconnected 3D fluorinated graphene host enables an ultrastable lithium metal anode

Abstract

Lithium metal has been considered the most promising anode material for lithium-ion batteries because of its high capacity and low electrochemical potential. However, the largest obstacle preventing its commercialization is the uncontrollable formation of dendrites. Herein, we designed an interconnected 3D fluorinated graphene frame as the host for lithium, which offers significantly improved cycling performance of the composite lithium metal anode. The uniform fluorination of a graphene sheet created a continuous lithophilic interface to lower the nucleation barrier for lithium and a porous structure to buffer the volume change. Meanwhile, the LiF-rich solid electrolyte interface (SEI) film conveniently formed and suppressed the formation of dead Li by preventing direct contact between the electrolyte and lithium metal. As a result, the modified anode exhibited excellent electrochemical performance. The Coulomb efficiency was maintained at nearly 99% after 280 cycles. The low overpotential of ∼15 mV was maintained in a symmetrical cell for 600 cycles. This dendrite suppression strategy realized on a fluorinated graphene-modified anode will accelerate its potential applications in future secondary lithium metal batteries.