Stabilizing nickel-rich layered oxide cathodes by magnesium doping for rechargeable lithium-ion batteries

Hang Li; Pengfei Zhou; Fangming Liu; Haixia Li; Fangyi Cheng; Jun Chen

doi:10.1039/c8sc03385d

Stabilizing nickel-rich layered oxide cathodes by magnesium doping for rechargeable lithium-ion batteries

Chem Sci. 2018 Nov 12;10(5):1374-1379. doi: 10.1039/c8sc03385d. eCollection 2019 Feb 7.

Authors

Hang Li¹, Pengfei Zhou^{1

2}, Fangming Liu¹, Haixia Li¹, Fangyi Cheng¹, Jun Chen¹

Affiliations

¹ Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education) , College of Chemistry , Nankai University , Tianjin 300071 , China . Email: fycheng@nankai.edu.cn.
² School of Chemistry and Chemical Engineering , Shandong University of Technology , Zibo 255049 , China.

Abstract

Nickel-rich layered transition metal oxides are attractive cathode materials for rechargeable lithium-ion batteries but suffer from inherent structural and thermal instabilities that limit the deliverable capacity and cycling performance on charging to a cutoff voltage above 4.3 V. Here we report LiNi_0.90Co_0.07Mg_0.03O₂ as a stable cathode material. The obtained LiNi_0.90Co_0.07Mg_0.03O₂ microspheres exhibit high capacity (228.3 mA h g^-1 at 0.1C) and remarkable cyclability (84.3% capacity retention after 300 cycles). Combined X-ray diffraction and Cs-corrected microscopy reveal that Mg doping stabilizes the layered structure by suppressing Li/Ni cation mixing and Ni migration to interlayer Li slabs. Because of the pillar effect of Mg in Li sites, LiNi_0.90Co_0.07Mg_0.03O₂ shows decent thermal stability and small lattice variation until it is charged to 4.7 V, undergoing a H1-H2 phase transition without discernible formation of an unstable H3 phase. The results indicate that moderate Mg doping is a facile yet effective strategy to develop high-performance Ni-rich cathode materials.