Impact of Dopants (Al, Mg, Mn, Co) on the Reactivity of Li_xNiO₂ with the Electrolyte of Li-Ion Batteries

First-principles computation of bulk O binding energies and Bader charges revealed the importance of Li content on thermal decomposition of charged high-nickel positive electrode materials for Li-ion batteries (Li x Ni 1-y M y O 2 , 0 < x < 1, y = 0, 0.05, M = Al, Mg, Mn, Co). The impact of individual dopants on the safety of these materials was studied using thermogravimetric analysis (TGA) and accelerating rate calorimetry (ARC) at two different states of charge corresponding to materials with two different Li contents. It was found that thermal stability strongly depends on the Li content of the material and that dopants serve to increase thermal stability by reducing the amount of Li removed from the material at a given voltage. This work sheds light on an unavoidable trade-off between high capacity and thermal stability for high-nickel materials.