The mixed metal oxide nanocomposites composed of spinel ZnFe 2O4 and wurzite ZnO phases are prepared by the heat-treatment for Zn,Fe-layered double hydroxide (Zn,Fe-LDH) at elevated temperatures. The following selective etching of ZnO domains from the nanocomposites yields porously assembled ZnFe2O4 nanocrystals. The structural transformation from the brucite LDH structure to the spinel and/or wurzite structures was confirmed by X-ray diffraction and X-ray absorption spectroscopy. According to chemical analysis, electron microscopy, and N2 adsorption-desorption isotherm measurements, not only the chemical composition of the nanocomposites but also the particle size and surface area of the etched ZnFe2O4 nanoparticles can be controlled by changing the Fe/Zn ratio in the precursor metal hydroxide. The calcined nanocomposites show promising functionality as negative electrode materials for lithium ion batteries, which is superior to that of uncomposited ZnFe2O4 or ZnO phase. The degrading of the electrode performance of the nanocomposites after the selective etching of ZnO component clearly demonstrates the positive effect of nanocomposite formation on the electrochemical activity of metal oxides.
Bibliographical noteFunding Information:
This work was supported by the Converging Research Center Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (20090093646), by the General R/D Program of the Daegu Gyeongbuk Institute of Science and Technology (DGIST), and by National Research Foundation of Korea Grant funded by the Korean Government (2010-0001485). The experiments at Pohang Accelerator Laboratory (PAL) were supported in part by MOST and POSTECH.
- Layered double hydroxide
- Lithium ion electrode
- Phase transformation
- Selective etching