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

ABSTRACT

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 TiO2 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.