Theoretical investigation on lithium battery material with improved light-harvesting performance

Abstract

Dye-sensitized photo-batteries employ dye molecules to photo-charge lithium-based batteries via utilizing the inexhaustible solar energy. In this manuscript, we reveal the atomistic structures and optoelectronic properties of the representative dye-sensitized photo-battery electrode material based on N719/LiFePO4 via first-principles calculations. Both tridentate and bidentate anchoring modes are available in the hybrid systems stabilized by the O···Li, H···O and S···Li interactions. The lithium ions are displaced from the LiFePO4 surface upon the dye adsorption, which is proposed to benefit the light-driven lithium ion movement in the photo-charging process. The band gap of the LiFePO4-based surface system reduces by 90% upon the dye adsorption, leading to a semi-metallic character that is associated with the decent electric conductivity. The Mulliken and Hirshfeld charges indicate the electron accumulation in the substrate, suggesting the electron flow from the dye to the substrate to stabilize to overall structure. This study facilitates the fundamental understanding on the dye-sensitized lithium battery materials and expects the integration of more dye-sensitized solar cell-active dyes and lithium battery materials for the light-weight photo-rechargeable battery application.