Utilizing Diverse Functions of Zirconium to Enhance the Electrochemical Performance of Ni-Rich Layered Cathode Materials

Abstract

Ni-rich cathode (Ni > 0.8) provides a low-cost and high-energy-density solution to the next-generation lithium-ion batteries. Unfortunately, severe capacity fading of Ni-rich cathode caused by the interfacial and bulk structural degradation impeded its application. Herein, Zr doping and Li6Zr2O7 coating are applied to a Ni-rich LiNi0.83Co0.12Mn0.05O2 (NCM) layered cathode material, and the modified material exhibits excellent cycle stability. The 1%Zr-NCM cathode material maintains a discharge capacity of 173.9 mAh g–1 at 1 C after 200 cycles in the 2.5–4.3 V voltage range at 25 °C, corresponding to a capacity retention of 94.6%; however, the unmodified NCM only delivers 129.9 mAh g–1 (capacity retention 68.6%). The synergistic effect of bulk Zr doping and surface Li6Zr2O7 coating improves the cycle stability of the Ni-rich material. Zr doped into the bulk could form a strong Zr–O bond to stabilize the layered structure, and Zr located in the Li layer can act as a pillar to maintain the layered structure and reduce Li+/Ni2+ mixing. In addition, the Li6Zr2O7 coating layer can also play a dual role in promoting Li+ migration and suppressing surface side reactions. This work demonstrates that sufficiently utilizing zirconium to enhance the electrochemical performance of cathode materials is a feasible and promising strategy.

Simple Strategy for Synthesizing LiNi0.8Co0.15Al0.05O2 Using CoAl-LDH Nanosheet-Coated Ni(OH)2 as the Precursor: Dual Effects of the Buffer Layer and Synergistic Diffusion

“…All of the refinements showed a good fit between the observed and calculated patterns, with R wp factors of less than 10%. The degree of cation mixing between the Li and Ni sites was calculated under the assumption that some Ni 2+ may occupy Li + sites given the similarity between the ionic radius of Ni 2+ (0.69 Å) and that of Li + (0.76 Å). , As shown in Table , the cell parameters of L­(N + CA) were smaller than those of L­(NC + A). Because the ionic radius of Al 3+ is smaller than those of Ni 3+ and Co 3+ , the smaller cell parameters indicate a greater doping concentration of Al 3+ in the crystal lattice.…”

“…The degree of cation mixing between the Li and Ni sites was calculated under the assumption that some Ni 2+ may occupy Li + sites given the similarity between the ionic radius of Ni 2+ (0.69 Å) and that of Li + (0.76 Å). 45,46 As shown in Table 2, the cell parameters of L(N + CA) were smaller than those of L(NC + A). Because the ionic radius of Al 3+ is smaller than those of Ni When the calcination temperature was 400 °C, the diffraction peaks of LiOH appeared in all three XRD patterns, indicating that most of the LiOH had not decomposed.…”

Revisiting the role of Zr doping in Ni-rich layered cathodes for lithium-ion batteries

“…34,35 In particular, Zr doping has been widely adopted for the layered oxides with various Ni contents, which is attributed to its effectiveness in improving the battery performance and its low cost. 34,[36][37][38][39][40] Even though the previous studies have verified the positive effect of Zr doping on the cathode electrochemical performance, there is still lack of understanding the beneficial effects of Zr doping mechanism on Ni-rich layered oxides. Specifically, an in-depth study of Zr doping effects on the lattice oxygen stability upon deep charge has not yet been performed, which requires further investigation of Zr doping in Ni-rich layered cathodes.…”

Synergistic Effects of Surface Coating and Bulk Doping in Ni‐Rich Lithium Nickel Cobalt Manganese Oxide Cathode Materials for High‐Energy Lithium Ion Batteries

“…[ 18 , 19 , 20 ] There is a broad range of cationic dopants that was investigated for Ni‐rich layered oxide cathode materials including, for example, Mg, Al, Ti, V, Mn, Fe, Co, Ga, Zr, and W.[ 21 , 22 , 23 , 24 , 25 , 26 , 27 ] Especially Zr as a high‐charge cation (Zr 4+ ) has been extensively reported with various beneficial effects, such as forming a strong Zr−O bond to stabilize the layered structure or Zr 4+ acting as pillar in the Li‐layer. [ 28 , 29 , 30 ] The variety of reported coatings is equally extensive, including organophosphates and metal oxides such as MgO, Al 2 O 3 , SiO 2 , La 2 O 3 , TiO 2 [ 21 , 31 , 32 , 33 , 34 , 35 ] and various reports using ZrO 2 or Li 6 Zr 2 O 7 . [ 30 , 36 ] The working principle of those coatings is still poorly understood, but surface protection of the secondary particle by HF scavenging is one of the proposed mechanisms.…”

“…[ 28 , 29 , 30 ] The variety of reported coatings is equally extensive, including organophosphates and metal oxides such as MgO, Al 2 O 3 , SiO 2 , La 2 O 3 , TiO 2 [ 21 , 31 , 32 , 33 , 34 , 35 ] and various reports using ZrO 2 or Li 6 Zr 2 O 7 . [ 30 , 36 ] The working principle of those coatings is still poorly understood, but surface protection of the secondary particle by HF scavenging is one of the proposed mechanisms. In addition, WO 3 ‐based coatings showed promising results in terms of improving cycle life and stabilizing the cathode/electrolyte interface of Ni‐rich cathodes.…”