Characterization of lithium nanobatteries and lithium battery nanoelectrode arrays that benefit from nanostructure and molecular self-assembly

Arrays of functioning nanobatteries were constructed by using nanoporous aluminum oxide membranes and sol–gel technology. These battery arrays had performance benefits derived from the nanoscale assembly and nanoscale structure of the various components. V2O5 ambigel used to make the nanobatteries was characterized by X-ray diffraction and found to be slightly crystalline in the bulk state, but it was completely amorphous when confined in the pores of aluminum oxide filter membranes. The gel confined in the pores served as cathodes for individual nanobatteries. PEO wax electrolyte was also confined in the pores and then coupled with a lithium metal anode. An a.c. impedance analysis indicated that there was little or no unstable passivation of the lithium anode in contact with the PEO wax electrolyte. This was attributed to a self-assembly process of a hydrocarbon layer at the surface of the wax preventing unwanted chemical reactions of the lithium with the electrolyte. Individual nanobatteries in the arrays were then characterized by charge/discharge tests using the cantilever tip of an atomic force microscope to make electrical contact with the 200 nm cathodes of the nanobatteries. Average volumetric capacities of these cells were found to be in the range of 23–30 μA h/cm2 μm, which is higher than similar systems found in the literature and can be attributed to the nanostructure of these systems.