The effects of alkali metal ions with different ionic radii substituting in Li sites on the electrochemical properties of Ni-Rich cathode materials

Tao He, Lai Chen*, Yuefeng Su, Yun Lu, Liying Bao, Gang Chen, Qiyu Zhang, Shi Chen, Feng Wu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

89 Citations (Scopus)

Abstract

The influences of alkali metal ions with different ionic radii substituting in Li sites on structure and electrochemical performances of Ni-rich cathode are systematically investigated. Li0.99M0.01Ni0.8Co0.1Mn0.1O2 (M = Li, Na, K, Rb) are synthesized by calcining Ni0.8Co0.1Mn0.1(OH)2 with lithium carbonate and other alkali carbonates. Diffraction analysis shows doping with alkali metal ions will not change the host layered structure. Specifically, alkali metal ion with appropriate ionic radius (Na+) dopes in Li site can enlarge Li slab space, decrease cation mixing and stabilize crystal structure by acting as “pillar ions”; while, the K+ and Rb+ ions with larger ionic radii dope in Li sites will block Li+ diffusion and cause lattice distortion. The capacity retention of the bare, Na+, K+ and Rb+ doped samples after 200 cycles at 1C within 2.8–4.3 V is 93.2%, 96.8%, 88.7% and 92.9%, respectively. The experimental results and theoretical calculations reveal that doping ions with appropriate ionic radii in Li sites are in favor of Li+ diffusion, while doping ions with overlarge ionic radii will deteriorate the structure and electrochemical performances of the cathode. We believe this study will benefit the future works for the Li-site doping of layered materials.

Original languageEnglish
Article number227195
JournalJournal of Power Sources
Volume441
DOIs
Publication statusPublished - 30 Nov 2019

Keywords

  • Alkali metal ions
  • Doping
  • Li site
  • Lithium ion battery
  • Ni-rich cathode material

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