The Effect of Doping Process Route on LiNiO$_2$ Cathode Material Properties

The pursuit of higher energy density in lithium-ion batteries has driven the increase of the nickel content in lithium nickel cobalt manganese oxide cathode active materials (CAMs), ultimately approaching LiNiO$_2$ (LNO). The downside of the high specific capacity of LNO is more severe degradation of the CAM during battery operation. A common approach to increase structural stability is the introduction of dopants. Various dopants are discussed and compared with each other when integrated into the CAM and tested against undoped materials in the literature, but little attention is given to the role of the process route of their introduction. In this work, we demonstrate with a series of nominally equally Zr-doped LNO samples that effects on various physico- and electrochemical properties are due not to the dopant itself, as one would assume in comparison to an undoped sample, but to the process route and the resulting particle morphology. Dopant, concentration and process routes (co-precipitation, impregnation and co-calcination) were chosen based on their significance for industrial application.