Understanding the Role of Various Dopant Metals (Sb, Sn, Ga, Ge, and V) in the Structural and Electrochemical Performances of LiNi_0.5Co_0.2Mn_0.3O₂

Abstract

Ni-rich layered oxides have been widely applied commercially due to their high energy density and capacity. However, there are still some drawbacks of capacity fading, O 2 release, and Li/Ni exchange. Cation doping has been proven to be one of the most promising strategies to improve the electrochemical performances of Ni-rich layered oxides. Herein, density functional theory (DFT) calculations have been performed to investigate the effects of doping various cations (Sb 5+ , Sn 4+ , Ga 3+ , Ge 4+ , and V 5+ ) on the structural stability and electrochemical performances of LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523). The theoretical results show that Sb, Sn, Ga, Ge, and V doping can reduce the oxidation state of Ni ions. Moreover, doping with these metals can inhibit O 2 release and Li/Ni exchange, which improves the safety, capacity retention, and rate capacity. Furthermore, Ga and Ge doping can improve the stability of partially deintercalated states, suppress lattice distortion, and increase the intercalation voltage. In conclusion, Ga and Ge doping is an effective strategy to optimize the electrochemical performances of NCM523.

In Situ Co-modification Strategy for Achieving High-Capacity and Durable Ni-Rich Cathodes for High-Temperature Li-Ion Batteries

“…Notably, 1.0% V-NCM@ZVO exhibits the slight cationic mixing of 1.07%. This may be explained by two opposite effects with the incorporation of high-valence V. The strong V–O bond (637 kJ mol –1 ) can significantly enhance the strength of surrounding Ni–O bonds, impeding the migration of Ni 2+ into the Li layer. − Besides, the increasing ratio of Ni 2+ aggravates the cation disorder as a result of the charge compensation. Hence, the modulation of the V content is essential for decreasing the cationic mixing, and 1.0% V-NCM@ZVO is the optimal sample with the greatest layered structure.…”

Enhancing surface‐to‐bulk stability of layered Co‐free Ni‐rich cathodes for long‐life Li‐ion batteries

“…Theoretical calculations indicate that Ge‐doping could effectively inhibit the O 2 release, creating a robust oxygen framework and reducing the cation mixing (Figure 1C). 26 The sluggish Li + migration is another factor restricting the development of Co‐free Ni‐rich layered oxides. Based on the DFT calculation, the doped Ge could effectively reduce the Li + diffusion barrier and accelerate the reaction kinetics 22,27 .…”

First-Principles Study of the Doping Effect in Half Delithiated LiNiO2 Cathodes

“…Nevertheless, there is a lack of systematic, comprehensive theoretical studies on the properties of various dopants in LiNiO 2 including the preferred occupation site, dopant ion migration, and the mechanism of dopants to suppress oxygen evolution. Candidate dopants, selected based on previous experimental and theoretical investigations, include B, 4 Na, 5 Mg, 6 Al, 7,8 Si, 9 Ca, 10 Ti, 8,11−13 V, 12,14 Cr, 15,16 Mn, 17,18 Fe, 19,20 Co, 11,19 Cu, 21 Zn, 22 Ga, 14,23 Ge, 14 As, Y, 24 Zr, 12,25 Nb, 26−28 Mo, 29,30 In, 31 Sn, 14,32 Sb, 13,14,33 La, 34 Ce, 34 Ta, 8,13,35 and W. 13,36,37 The ion migration from the Ni layer to the Li layer is most thermodynamically favored at x = 0.5 in Li x NiO 2 .…”

“…Nevertheless, there is a lack of systematic, comprehensive theoretical studies on the properties of various dopants in LiNiO 2 including the preferred occupation site, dopant ion migration, and the mechanism of dopants to suppress oxygen evolution. Candidate dopants, selected based on previous experimental and theoretical investigations, include B, Na, Mg, Al, , Si, Ca, Ti, ,− V, , Cr, , Mn, , Fe, , Co, , Cu, Zn, Ga, , Ge, As, Y, Zr, , Nb, − Mo, , In, Sn, , Sb, ,, La, Ce, Ta, ,, and W. ,, The ion migration from the Ni layer to the Li layer is most thermodynamically favored at x = 0.5 in Li x NiO 2 . − Thus, to study dopant ion migration, we use a 2 × 3 × 2 supercell of Li 0.5 NiO 2 as the base model, which contains 12 Li, 24 Ni, and 48 O. The chemical formula of our model can be approximated as Li 0.5 Ni 0 .…”