Accurate intercalation voltages for Li-ion cathodes from Hubbard-extended DFT*

The design of cathode materials for Li-ion batteries requires an accurate first-principle prediction of voltages in lithium oxides containing transition-metal (TM) atoms. For such systems, however, standard density-functional theory (DFT) approximations are unable to capture the correct amount of charge disproportionation that the TM atoms often undergo. In turn, this reflects in a poor description of the electronic structure at the intermediate lithium concentration, crucial for a quantitative prediction of voltages. It will be here shown how these shortcomings are bypassed when DFT is extended with the so-called Hubbard correction, in the form known as DFT+U+V method. [1] A systematic improvement for the predicted voltages is observed along with significant localization/hybridization interplay among d-electrons. In addition, we report on a recent implementation [2] of analytical Pulay forces allowing structural optimizations that benefit from the use of orthogonalized basis functions as projectors onto the Hubbard manifold.

[1] V. L. Campo Jr., M. Cococcioni, J. Phys.: Condens. Matter, 22, 055602 (2010)
I. Timrov, N. Marzari, M. Cococcioni, Phys. Rev. B 98, 085127 (2018)
[2] I. Timrov, F. Aquilante, M. Cococcioni, N. Marzari, arXiv:2010.13485