Recent advances of cobalt-free and nickel-rich cathode materials for lithium-ion batteries

In order to satisfy the rapidly increasing demands for a large variety of applications, there has been a strong desire for low-cost and high-energy lithium-ion batteries (LIBs) and thus for next-generation cathode materials having low cost yet high capacity. In this regard, the research of cobalt (Co)-free and nickel (Ni)-rich (CFNR) layered oxide cathode materials, able to meet the low-cost and high-capacity requirements, has been extensively pursued but remains challenging largely due to the elimination of Co and high content of Ni in these materials. Herein, we systematically review the challenges and recent advances of CFNR cathode materials on these important aspects. Specifically, we first clarify the role of Co in Ni-rich layered oxides and the possibility of its elimination to fabricate CFNR cathode materials. We then discuss the methods developed to synthesize CFNR cathode materials. This is followed by the elucidation about the degradation mechanisms of CFNR cathode materials and the research progress of modification strategies achieved in enhancing the properties for these materials. Finally, we discuss the current challenges and future prospects of CFNR cathode materials as the next-generation cathode materials for low-cost and high-energy LIBs.