Lithium nickel manganese cobalt oxide (NMC) is one of the dominant cathode materials in lithium-ion batteries. Here a simple, efficient and scalable surface doping technique is successfully demonstrated, which can be readily used in mass production of cathode materials. For the first time neodymium oxide (Nd2O3) has been employed as the surface doping agent. The Nd-doped NMC shows greatly improved cycling and rate performance, and the enhanced cycling stability has been demonstrated in full pouch cells, with a 17.5% increase in capacity retention after 300 cycles. Fewer cracks have been observed in the doped NMC after cycling, and in situ X-ray diffraction reveals the suppressed lattice collapse by Nd doping. Greatly suppressed surface phase change has been confirmed by HR-TEM and EELS. The result suggests great promise in using this dry doping technique to enhance the electrochemical performance of NMC cathodes.

Yang Shi, Kitae Kim, Yingjie Xing, Andrew Millonig, Bryan Kim, Lixin Wang, Eunsung Lee, Chloe Harrison, Taehwan Yu, Derek C. Johnson, Albert L. Lipson, Jessica L. Durham, Donghao Liu, Timothy T. Fister, Lei Yud, Jianguo Wen, “Facile and scalable dry surface doping technique to enhance the electrochemical performance of LiNi[subscript 0.64]Mn[subscript 0.2]Co[subscript 0.16]O[subscript 2] cathode materials,” J. Mater. Chem. A 8 (38), 19886-19872 (2020). DOI: 10.1039/d0ta07779h abstract

SEM images of (a) the mixture of Nd2O3 and NMC powder before sintering, (b) Nd-doped NMC (after sintering)-high magnification, (c) Nd-doped NMC-low magnification, and (d) Nd EDS mapping of Nd-doped NMC.

Cross-section SEM images of (a) the pristine and (b) Nd-doped NMC after 300 cycles in SLP cells.