Confinement of TiO2 quantum dots in graphene nanoribbons for high-performance lithium and sodium ion batteries

Abstract

A hybrid-material of titanium-oxide quantum dots (QDs) anchored on graphene nanoribbons (TiO2@GNRs) was prepared by a simple hydrolysis strategy followed by heat-treatment. The GNRs can effectively accelerate the charge transference in the TiO2@GNRs. And the TiO2 QDs of ~5 nm can be thoroughly lithiatied/sodiated in electrically confined space of GNRs. Motivated by its unique structure, the electrochemical charge/discharge behaviors of the TiO2@GNRs serving as anodes for Li/Na-ion batteries (LIBs/SIBs) were evaluated. Reversible charge capacities of 320.8 mAh g−1 for LIBs and 101.6 mAh;g−1 for SIDs were demonstrated over 100 cycles at a rate of 0.5 A g−1, respectively. And Li and Na storage capacities of 209.0 and 42.2 mAh g−1 were retained at 8.0 A g−1, respectively. The desirable charge capacities, stable cyclic ability, and excellent rate performance of TiO2@GNRs can be ascribed to the ultra-small TiO2 size benefiting for full insertion/extraction of alkali ions and shortening their transfer pathway as well as enhanced electronic and ionic conductivity of the overall electrodes and interfacial confinement of GNRs for maintaining the electrode integrity.