Zinc oxide, as an inexpensive anode material, has attracted less attention than other metal oxides due to its poor cycling stability. A rational design of ZnO nanostructures with well-controlled particle sizes and microstructures is essential in order to improve their stability and performance as electrodes for lithium ion batteries (LIBs). Here, we demonstrate a simple approach via atomic layer deposition (ALD) to synthesize ZnO quantum dots (QDs) on graphene layers, in which the size of the ZnO QDs can be controlled from 2 to 7 nm by ALD cycles. A strong relationship between size and electrochemical performance is observed, in which smaller sized QDs on graphene display enhanced electrochemical performance. A high reversible specific capacity of 960 mA h g-1 is achieved at a current density of 100 mA g-1 for 2 nm ZnO QDs, approaching to the theoretical value of ZnO as the LIB anode. The greatly enhanced cycling stability and rate performance of the ALD ZnO QD/graphene composite electrode can be attributed to the well-maintained structural integrity without pulverization upon electrochemical charge/discharge for ZnO QDs with the grain size below a critical value.
All Science Journal Classification (ASJC) codes
- Renewable Energy, Sustainability and the Environment
- Materials Science(all)