Enhanced Cycling Stability of LiCuxMn1.95−xSi0.05O4 Cathode Material Obtained by Solid-State Method

Abstract

The LiCuxMn1.95−xSi0.05O4 (x = 0, 0.02, 0.05, 0.08) samples have been obtained by a simple solid-state method. XRD and SEM characterization results indicate that the Cu-Si co-doped spinels retain the inherent structure of LiMn2O4 and possess uniform particle size distribution. Electrochemical tests show that the optimal Cu-doping amount produces an obvious improvement effect on the cycling stability of LiMn1.95Si0.05O4. When cycled at 0.5 C, the optimal LiCu0.05Mn1.90Si0.05O4 sample exhibits an initial capacity of 127.3 mAh g−1 with excellent retention of 95.7% after 200 cycles. Moreover, when the cycling rate climbs to 10 C, the LiCu0.05Mn1.90Si0.05O4 sample exhibits 82.3 mAh g−1 with satisfactory cycling performance. In particular, when cycled at 55 °C, this co-doped sample can show an outstanding retention of 94.0% after 100 cycles, whiles the LiMn1.95Si0.05O4 only exhibits low retention of 79.1%. Such impressive performance shows that the addition of copper ions in the Si-doped spinel effectively remedy the shortcomings of the single Si-doping strategy and the Cu-Si co-doped spinel can show excellent cycling stability.

Improved Electrochemical Properties of LiMn2O4-Based Cathode Material Co-Modified by Mg-Doping and Octahedral Morphology

“…For the LiMn 1.95 Mg 0.05 O 4 and octahedral LiMn 1.95 Mg 0.05 O 4 samples, the initial charge–discharge curves show similar platform characteristics, and the potential interval of the Mg-doped spinels is less than that of the undoped spinel, suggesting the higher reaction kinetics of the Mg-doped spinels [39]. It is important to note, however, that the discharge voltage plateaus of the LiMn 1.95 Mg 0.05 O 4 samples are slightly higher than that of the undoped LiMn 2 O 4 sample, which may be related to the optimization of the Li + intercalation/deintercalation behaviors due to the addition of other cations in the spinel structure [10,33,39,40].…”

“…Figure 8a presents the Nyquist plots of the LiMn 2 O 4 and octahedral LiMn 1.95 Mg 0.05 O 4 samples, and Figure 8b shows the corresponding equivalent circuit model. According to the research result [9,10,23], the charge transfer resistance (R 2 ) in the high-frequency region has strong ties to the electrochemical properties. Therefore, we mainly studied the R 2 value to confirm the effect of both the Mg-doping and octahedral morphology on the electrochemical performance.…”

“…All these advantages can promote large-scale applications of LiMn 2 O 4 . It must be noted, however, that the cycling stability and high temperature performance cannot meet the requirement of long endurance mileage [9,10,11,12].…”

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

“…Among these materials, LiMn 2 O 4 shows many virtues such as mature production technology, cheap production costs, non-pollution characteristics, and so forth [17,18,19,20]. However, the large-scale commercial applications of this material have been seriously restricted because of its poor cycling life and high-temperature performance, which are mostly a consequence of Jahn–Teller distortion, manganese dissolution, and non-uniform particle-size distribution [7,21,22,23,24]. Therefore, there is a tremendous need to optimize this material for better performance.…”

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.…”