(173g) Binderless Cobalt Oxide Nanoparticle Films Through Electrophoretic Deposition, for Li-Ion Batteries

            Nanoscale
materials for Li-ion battery electrodes have received great attention due to
their high surface-to-volume ratio and reduced Li-ion diffusion length which
results in faster charge/discharge. Nanomaterials
also show the ability to accommodate strain through volume expansion without pulverization
or capacity fading. In this work we have developed a hollow cobalt oxide NP film
for Li-ion battery electrodes that require no additional support materials such
as carbon black or polymers to establish good electrical pathways. The
colloidal cobalt NPs are prepared by decomposition of organometallic
precursors in non-aqueous conditions. The NP film is formed by using electrophoretic deposition (EPD). During EPD, a film is
formed on both the cathode and anode but the film on the anode is slightly
thicker than that of the cathode, which indicates that more particles are
negatively charged. The EPD deposited films are calcined
to form hollow cobalt oxide (Co₃O₄) NPs that act as the battery
anode. Battery cycling of these anodes show low
degradation and are near the theoretical capacity limits for this material. These
results are surprising since control experiments made from dropcast
films form poor battery contacts under the same calcination and battery-test conditions.