Synthesis and Storage Performance of the Doped LiMn[sub 2]O[sub 4] Spinel

Abstract

A series of spinel-doped lithium manganese oxides, Li x Mn y Ti z O 4.00 ͑0.973 Յ x Յ 1.018, 1.893 Յ y Յ 1.959, z Ϸ 0.050͒, Li x Mn y Ti z Ni m O 4.00 ͑0.981 Յ x Յ 1.010, 1.903 Յ y Յ 1.951, z Ϸ 0.050, m Ϸ 0.030͒, Li x Mn y Ti z Co m O 4.00 ͑0.953 Յ x Յ 1.004, 1.912 Յ y Յ 1.968, z Ϸ 0.050, m Ϸ 0.009͒, have been prepared using the solid-state reaction of a titanium-doped electrolytic manganese dioxide, lithium hydroxide, and doping agents. The oxides have been characterized using several advanced techniques, such as X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared analysis, Raman spectroscopy, thermogravimetric analysis, differential scanning calorimetry, cyclic voltammograms and charge/discharge cycles. The experimental results show that the Li 0.973 Mn 1.893 Ti 0.048 O 4.00 sample, prepared at 600°C, showed the best electrochemical performance during the charge/discharge tests and storage process in all samples. In the voltage region of 4.6-2.5 V, the initial capacities of the fresh, discharge-storage, and charge-storage cell for the Li 0.973 Mn 1.893 Ti 0.048 O 4.00 sample are 206, 144, and 175 mA h g −1 , respectively. In the voltage region of 4.3-3.4 V, the capacity fade of the sample was 5.3% in 150 cycles. After being doped by titanium ions, the spinel Li 0.973 Mn 1.893 Ti 0.048 O 4.00 exhibits a lower lattice constant and stronger Mn-O bond than a pure spinel does.

Enhancing the durable performance of LiMn2O4 at high-rate and elevated temperature by nickel-magnesium dual doping

“…19 prepared the Ni-Mg co-doped LiMn 2 O 4 cathode materials using microwave irradiation as a sintering technique. The resultant LiNi 0.03 Mg 0.02 Mn 1.95 O 4 delivered a capacity of about 120.0 mAh·g −1 at 1 C and remained 90.6 mAh·g −1 at a high current rate of 10 C. Even at an elevated temperature of 55 °C, the LiNi 0.03 Mg 0.02 Mn 1.95 O 4 also obtained the high capacity of 90.0 mAh·g −1 at a higher rate of 10 C. In addition to the Ni-Mg co-doping strategy, other metals such as Ni-Mo 20 , Mg-Si 21 , and Ni-Ti co-doping 22 were also employed to improve the cycling property and structure stability of spinel LiMn 2 O 4 cathode materials. For these dual-doped LiMn 2 O 4 cathode materials, the traditional preparation methods including high-temperature solid-state reaction, sol-gel method, microwave irradiation and so on need long reaction time, high temperature and troublesome pre-treatment.…”

Microwave-assisted optimization of the manganese redox states for enhanced capacity and capacity retention of LiAlxMn2−xO4 (x = 0 and 0.3) spinel materials

“…14, 15 The stress generated by this phenomenon leads to cracking of particles and loss of electric contact upon cycling. The manganese ions in LMO are believed to exist as 50% Mn 3+ and 50% Mn 4+ (i.e., n Mn ¼ 3.5+).…”

“…12,13 The Jahn-Teller effect is the reduction of the crystal symmetry from cubic to tetragonal structure, and it is this structural transition that deteriorates its cycle life and is said to occur when the average manganese valence number (n Mn ) is equal or less than 3.5. 14,15 The stress generated by this phenomenon leads to cracking of particles and loss of electric contact upon cycling. The manganese ions in LMO are believed to exist as 50% Mn 3+ and 50% Mn 4+ (i.e., n Mn ¼ 3.5+).…”

Mapping of Phase Diagram and Electrode Properties in Spinel-type LiNi_<i>x</i>Mn_{2-<i>x</i>-<i>y</i>}Ti_<i>y</i>O₄ Cathodes for Lithium-Ion Batteries

“…4,6 To improve these problems, the substitution of Mn with various transition metal elements such as Cr, Co, Fe, Ni, and Ti were often performed. [7][8][9][10][11] The Ni substituted spinel compound, LiNixMn2-xO4, exhibited a smaller amount of Mn dissolved in comparison with the non-substituted LiMn2O4. In addition, LiNi0.5Mn1.5O4 with x = 0.5 showed a high voltage plateau associated with Ni 4+ /Ni 2+ at around 4.7 V (vs. Li + /Li).…”