The pore structure in nano-porous TiO2 coatings influences the ion diffusion property and the photovoltaic performance of dye-sensitized solar cells. In this paper, TiO2 coatings were deposited by vacuum cold spray (VCS) using a strengthened nanostructured powder. The pore structure, ion diffusion, and dye infiltration properties were examined to understand the coating deposition mechanism. Results showed that the pores in the VCS TiO2 coatings presented a bimodal size distribution with two peaks at ~15 and ~50 nm. Based on the impact behavior of spray powder particles, a deposition model was proposed to explain the formation mechanism of the pores in the VCS coating using strengthened nanostructured powder. It was found that, compared to the conventional unimodal-sized nano-pores in TiO2 coatings, the bimodal-sized nano-pores contributed to a higher ion diffusion coefficient of the coatings and thereby a higher photovoltage of the solar cells.