Enhanced Cycling Stability through Erbium Doping of LiMn2O4 Cathode Material Synthesized by Sol-Gel Technique

Abstract

In this work, LiMn2−xErxO4 (x ≤ 0.05) samples were obtained by sol-gel processing with erbium nitrate as the erbium source. XRD measurements showed that the Er-doping had no substantial impact on the crystalline structure of the sample. The optimal LiMn1.97Er0.03O4 sample exhibited an intrinsic spinel structure and a narrow particle size distribution. The introduction of Er3+ ions reduced the content of Mn3+ ions, which seemed to efficiently suppress the Jahn–Teller distortion. Moreover, the decreased lattice parameters suggested that a more stable spinel structure was obtained, because the Er3+ ions in a ErO6 octahedra have stronger bonding energy (615 kJ/mol) than that of the Mn3+ ions in a MnO6 octahedra (402 kJ/mol). The present results suggest that the excellent cycling life of the optimal LiMn1.97Er0.03O4 sample is because of the inhibition of the Jahn-Teller distortion and the improvement of the structural stability. When cycled at 0.5 C, the optimal LiMn1.97Er0.03O4 sample exhibited a high initial capacity of 130.2 mAh g−1 with an excellent retention of 95.2% after 100 cycles. More significantly, this sample showed 83.1 mAh g−1 at 10 C, while the undoped sample showed a much lower capacity. Additionally, when cycled at 55 °C, a satisfactory retention of 91.4% could be achieved at 0.5 C after 100 cycles with a first reversible capacity of 130.1 mAh g−1.

High-Performance Lithium-Ion Hybrid Supercapacitors Based on Lithium Salt/Imidazolium Ionic Liquid Electrolytes and Ni-Doped LiMn2O4 Cathode Materials

“…LiNi x Mn 2– x O 4 delivered 137.0 mAh g –1 ( x = 0.01), 135.2 mAh g –1 ( x = 0.03), 136.6 mAh g –1 ( x = 0.05), 136.8.0 mAh g –1 ( x = 0.08), and 120.9 mAh g –1 ( x = 0.10) at the lower current rate of C/5, comparable to other previously reported LMO and LNMO. ,,,,,,− ,,,− The lower capacity of the material with a higher Ni concentration can be associated with what was described previously. , Xu and Meng performed theoretical studies to understand the diffusion processes of lithium in the spinel structure. These authors have concluded that the different valence states of Mn ions and their arrangements, surrounding the lithium ions affect the activation barrier of lithium diffusion in the spinel structure.…”

Zr-doping stabilizes spinel LiMn2O4 as a low cost long cycle life cathode for lithium ion batteries

“…Doping with foreign ions, including cations such as Li + , Na + , Mg 2+ , Zn 2+ , Cu 2+ , Ni 2+ , Al 3+ , Fe 3+ , Co 3+ , Cr 3+ , Ga 3+ , La 3+ , Ce 3+ , Nd 3+ , and also anions F − , S 2− , B 3− have been reported to effectively improving cycle life. [7][8][9][10][11]14,[18][19][20][21][22][23][24][25][26][27][28][29][30][31] Most of those ions (e.g., Cu 2+ , Ni 2+ , Co 3+ , Cr 3+ ) preferred to occupy 16d sites, substituting Mn 3+ , increasing the average valence of Mn to over 3.5, while some (e.g., Zn 2+ and Ga 3+ ) preferred to 8a sites. [11] So the occupying of the dopant determines the structural stability and electrochemical performance such as discharge specific capacity and cycle performance at room temperature and high temperature.…”