What is the role of titanium doping in improving the electrochemical properties of lithium manganese acid batteries?

LiMn2-xTIxO4(X ≤ O .1) prepared by solid phase method with nanometer titanium dioxide(VK-TA18) as doping body, Mn2O3, and Li2CO3 as raw materials, with a single phase spinel structure, With the increase of the amount of nanometer titanium dioxide(VK-TA18), the cell volume increases. The appropriate amount of nanometer titanium dioxide(VK-TA18) doping increases the first discharge specific capacity of the material, the amount of nanometer titanium dioxide(VK-TA18) doping is too large, and the first discharge specific capacity of the material is reduced. The inclusion of nanometer titanium dioxide(VK-TA18) refined spinel particles, increased particle dispersion, and enhanced the diffusion ability of Li + ions in the solid phase. The cyclic properties of the coated titanium dioxide(VK-TA18) material were improved and the reversibility of the electrode reaction was enhanced. 21 and 55 °C, 1C ratio, the first discharge ratio capacity of LiMn1.995 TI 0.005O4 was 100.74 and 102.05 mAh/g, respectively, and the cycle 50 cycle capacity retention rate was 94.12 and 88.82, respectively. An appropriate amount of nanometer titanium dioxide(VK-TA18) doping can effectively improve the capacity attenuation of spinel LiMn2O4.

The first discharge specific capacity of the positive materials LiMn2O4 and LiMn2-xTIxO4 at 21 and 55 °C, with a voltage range of 3.O to 4.2 V, 1C times, was the largest(21 °C: 102.78 mAh/g, 55 °C: 105.76 mAh/g), exceeding the initial discharge ratio capacity of the undoped LiMn2O4(21 °C: 100.08 mAh/g, 55 °C: 101.82 mAh/g). The cell volume of the titanium-doped material X = 0.005 is appropriately increased, and the diffusion channel of the Li Ion is increased, which is more conducive to the deembedding of the Li Ion. The increase of the capacity of the first discharge ratio is the reason why the electrochemical polarization becomes smaller and the diffusion capacity of Li ions increases during the process of charging and discharging. With the increase of titanium-doped X, the first discharge specific capacity of the material is reduced at 21 and 55 °C. This may be due to the increase of titanium doping, which reduces the content of the active substance, resulting in a decrease in the first discharge specific capacity. In summary, titanium doped material X = 0.005 has both high initial discharge specific capacity and good room temperature and high temperature cycle performance. The first discharge specific capacity of constant and high temperature is: 100.74 and 102.05 mAh/g, respectively. The cycle 50 cycle capacity retention rates are 94.12 and 88,829,5, respectively, which may be related to the appropriate cell volume and stable spinel structure. After adding titanium dioxide(VK-TA18), the cell volume of the material increases, which improves the diffusion capacity of Li ions. During the process of charging and discharging, the removal and embedding of Li ions have less effect on the diffusion channel. Therefore, the proper amount of TI admixture is beneficial to the recycling performance of the material. However, the amount of doped nanometer titanium dioxide(VK-TA18) is too large, the cell volume of the material is too large, and the binding energy in the crystal body is reduced, resulting in excessive lattice distortion, which destroys the ordering of ions in the lattice and is detrimental to the formation of diffusion channels. This results in the attenuation of capacity and the deterioration of circulation performance.

Therefore, the nanometer titanium dioxide(VK-TA18) doped amount X = 0.005 is the best.

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