Enhancement of Electrochemical Properties of Lithium Rich Li2RuO3 Cathode Material

Abstract

Lithium-rich layered Ru-based oxides are interesting cathode materials due to their high energy density and reversible capacity. However, their poor structural stability and voltage decay hinder their broad commercial applicability. To address this, we investigate the co-doping strategy on Li2RuO3 (LRO) for improved battery performance using a combination of quantum mechanics, molecular dynamics, and pseudo-1-dimensional (P1D) formulations. Specifically, in addition to the effect of Ti as a dopant in Li2Ru0.5Ti0.5O3 (LTO), the effect of three co-dopants, Tc, Rh, or Pd in Li2Ru0.5Ti0.25M0.25O3 has also been studied. It has been found that the co-doping strategy significantly improves the thermal stability of LRO. Tc and Ti improve structural stability by reducing the oxygen removal reaction. Pd and Tc reduce the bandgap considerably, leading to higher electrical conductivity. The results show that co-doping minimizes the energy required for Li-ions diffusion. In particular, Tc significantly enhances the Li-ions diffusion in LRO and LTO. Further co-dopants Rh, Pd, and Tc improve the maximum voltage of LRO, as well as the voltage stability by reducing the voltage reduction. Finally, P1D simulations show that while LTO provides the highest voltage and power operation, doping it with Tc and Pd increases its efficiency by reducing the ohmic potential drop and diffusion polarization.