Layered double hydroxide nano- and microstructures grown directly on metal substrates and their calcined products for application as Li-ion battery electrodes

Layered double hydroxide (LDH) nano- and microstructures with controllable size and morphology have been fabricated on "bivalent metal" substrates such as zinc and copper by a one-step, room-temperature process, in which metal substrates act as both reactants and supports. By manipulating the concentration of NH3 center dot H2O, the thickness and lateral size of the LDH materials can be tuned from several tens of nanometers to several hundreds of nanometers and from several hundreds of nanometers to several micrometers, respectively. This method is general and may be readily extended to any other alkali-resisted substrate coated with Zn and Cu. As an example, Zn-covered stainless steel foil has been shown to be effective for the growth of a Zn-Al LDH film. After calcinating the as-grown LDH at high temperature (650 degrees C) in argon gas, a ZnO/ZnAl2O4 porous nanosheet film is obtained, which is then directly used for the first time as the anode material for Li-ion batteries with the operating voltage window of 0.05-2.5 V (vs. Li). The result demonstrates that ZnO/ZnAl2O4 has higher discharge and charge capacities and considerably better cycling stability compared to pure ZnO (Li insertion/extraction rate: 200 or 500 mA g(-1)). The improved electrochemical performance can be ascribed to the buffering effect of the inactive matrix ZnAl2O4 by relieving the stress caused by the volume change during charge-discharge cycling. This Work represents a successful example for the development of promising ZnO-based anode materials for Li-ion batteries.