Understanding the Feasibility of Manganese Substitution for Cobalt in the Synthesis of Nickel-Rich and Cobalt-Free Cathode Materials

LiNi0.8Co0.15Al0.05O2 (LNCA) cathode materials have an extremely high energy density, which can greatly enhance the driving range of pure electric vehicles if they are used in on-board batteries. However, the development of the LNCA cathode material is restricted by the expensive transition metal cobalt (Co). Therefore, researchers are devoted to finding other metals to replace Co to synthesize nickel (Ni)-rich Co-free materials to reduce the cost. To investigate the feasibility of replacing Co with manganese (Mn) as a transition metal, this paper reports the synthesis and compares the properties of four Ni-rich materials with different Co-Mn contents by gradually adding Mn to LNCA materials and reducing the Co content in equal amounts using an oxalic acid coprecipitation method. The results show that Mn can compensate the effect of Co deficiency to a certain extent; it is feasible to use Mn to completely replace Co in the synthesis of Ni-rich ternary Co-free materials under the premise of sacrificing a certain initial specific capacity. The tetrameric material LiNi0.8Co0.1Mn0.05Al0.05O2 substituted with trace amounts of Mn exhibited the most excellent electrochemical properties among the four synthesized materials. Therefore, to synthesize satisfactory Ni-rich Co-free materials, it is suggested to develop and synthesize quaternary Co-free materials on the basis of LiNi0.8Co0.1Mn0.05Al0.05O2.