What makes a Ru-based compound a viable Li-ion insertion material?

Density functional theory (DFT) can be used to calculate the properties of Li-ion battery materials, including insertion potential In this paper, we compare Li + intercalation in the layered compound Li 2 RuO 3 We use DFT to fully relax the crystal structure at each Li + concentration and for several different Li + ion configurations where possible. Choosing the lowest energy configuration, we calculated the intercalation potential vs. a Li metal anode. The details of the electronic structure were examined to determine the microscopic origin of properties relevant to good electrochemical performance, such as structural stability and electrical conductivity. The calculations are consistent with measurements predicting that Li 2 RuO 3 is a good electrical conductor with an intercalation potential around 3.1 V and a flat charge/discharge profile. Calculations also show that Li + combines with RuO 2 by two processes, either at 1.9 V by the intercalation of Li + into the rutile 2c sites to form Li x RuO 2 (figure 3), or by the formation of an inhomogeneous mixture of Li 2 O and Ru metal at 2.1 V. The latter process is energetically favored by 0.2 V, explaining why it is the practical product of the electrochemical interaction of RuO 2 and Li