Atomic layer deposition of amorphous TiO₂ on graphene as an anode for Li-ion batteries

Atomic layer deposition (ALD) was used to deposit TiO₂ anode material on high surface area graphene (reduced graphene oxide) sheets for Li-ion batteries. An Al₂O₃ ALD ultrathin layer was used as an adhesion layer for conformal deposition of the TiO₂ ALD films at 120 ° C onto the conducting graphene sheets. The TiO₂ ALD films on the Al₂O₃ ALD adhesion layer were nearly amorphous and conformal to the graphene sheets. These nanoscale TiO₂ coatings minimized the effect of the low diffusion coefficient of lithium ions in bulk TiO₂. The TiO₂ ALD films exhibited stable capacities of ∼120 mAh g^-1 and ∼100 mAh g^-1 at high cycling rates of 1 A g^-1 and 2 A g^-1, respectively. The TiO ₂ ALD films also displayed excellent cycling stability with ∼95% of the initial capacity remaining after 500 cycles. These results illustrate that ALD can provide a useful method to deposit electrode materials on high surface area substrates for Li-ion batteries.