Energy storage has become increasingly important in recent years due to the rapidly increasing number of electric vehicles (EVs) in use and expanded utilization of intermittent renewable energy sources. Improvements in longevity, energy density, and high rate capability are needed for the next generation of batteries. Lithium-ion batteries (LIBs), the most widely commercialized rechargeable batteries are being used in EVs and some pilot grid-scale storage facilities.

One avenue for enhancing the performance of LIBs is the development of novel electrode materials. One such material, titanium dioxide (TiO₂) exhibits very high stability during cycling and is capable of ultra-high rate charging and discharging. However, a major drawback to TiO₂ is its relatively low electrical conductivity, which limits its performance. Using nanostructured, one-dimensional morphologies the issue of low conductivity can be mitigated. Additionally, metal-doping of TiO₂ with various metallic cations such as zinc, copper, or niobium has been shown to increase conductivity as well.

Aerosol chemical vapor deposition (ACVD) is an atmospheric pressure technique used to deposit nanostructured metal oxide thin films. In ACVD, a vapor phase organometallic precursor is fed to a reactor and undergoes thermal degradation forming metal oxide monomers. The monomers nucleate to form particles which undergo condensational growth before depositing onto a heated substrate, where the particles sinter into various morphologies. Controlling the rates of these processes using various system parameters leads to the deposition of one-dimensional, columnar structures. Additionally, by introducing two precursors simultaneously doped materials can be synthesized, with the composition controlled by the relative flowrates into the reactor.

In this work, we aim to investigate the effect of Cu-doping on the properties and performance of nanostructured TiO₂ negative electrodes in LIBs. To achieve this, Cu-doped TiO₂ films with compositions between 0-10 at% are synthesized on stainless steel using ACVD and directly utilized as anodes in LIBs. In order to determine the effect of Cu-doping on battery performance a rate capability test is performed by cycling the batteries at progressively higher rates. Additionally, long-term cycling is performed to determine the stability of the electrodes. Additionally, characterization of the lithium diffusion coefficient is performed using both cyclic voltammetry (CV) and galvanostatic intermittent titration technique (GITT). Finally, density function theory (DFT) simulations are performed in order to validate the experimentally measured values for the lithium diffusion coefficient and the electrical conductivity.