Preparation method of lithium titanium negative electrode composite material for lithium ion battery

[0020] Example 1

[0021] According to the molar ratio Li:Ti=1, lauric acid:Ti=1:5, weigh 8.51g of tetrabutyl titanate (analytical purity), 2.55g of lithium acetate (analytical purity) and 1g of lauric acid (analytical purity) ), respectively, dissolve them in 12ml of absolute ethanol. Add the ethanol solution of lithium acetate dropwise to the ethanol solution of tetrabutyl titanate, mix well under magnetic stirring, and react for about 10 minutes, then add the ethanol solution of lauric acid to the mixed solution, and react for 15 hours at room temperature Around, get a uniform milky white gel. The gel was aged in the air for 24 hours, and dried in an oven at 100°C to obtain a pale yellow precursor. Put the precursor into a ball milling tank, add an appropriate amount of agate balls, and ball mill on a ball mill at a speed of 380 r/min for 2 hours to obtain superfine precursor powder. Put the powder in a muffle furnace and heat up to 500°C for 6 hours at a heating rate of 150°C/hour to preliminarily decompose the raw materials. After the temperature drops to 20~50°C, the temperature is raised to a temperature of 160°C/hour. Keep the temperature at 800℃ for 10 hours to obtain Li with spinel structure 4 Ti 5 O 12. figure 1 The XRD pattern of the obtained sample. by figure 2 It can be seen that the positions and relative intensities of the diffraction peaks of the XRD pattern of the synthesized product are all consistent with Li 4 Ti 5 O 12 The standard cards match, without any miscellaneous phases. figure 2 For the field emission scanning photos of the obtained samples, the particle size is about 120-275nm, the distribution is relatively concentrated, and there is basically no agglomeration, indicating that the use of lauric acid as a dispersant can effectively reduce particle agglomeration and prepare highly dispersed nanocrystals. image 3 In order to use this material as the positive electrode and the metal lithium sheet as the negative electrode to form a simulated battery, the first charge-discharge curve at 0.5C, 1C and 2C magnification shows that the synthesized material has an excellent charge-discharge platform and high The reversible capacity, the first charge-discharge capacity at 0.5C can reach the theoretical capacity of 174.7mAh/g, the charge-discharge platform is flat, and it shows good lithium insertion performance. Figure 4 At 0.5C, 1C and 2C rate, the discharge cycle curve of the sample shows that the material exhibits good cycle performance and is an excellent electrode material.

[0022] Example 2

[0023] Synthesize 0.005mol Li 4 Al 0.15 Ti 4.85 O 12 According to the molar ratio Li:Ti:Al=80:97:3, weigh 8.25g tetrabutyl titanate (analytical pure), 2.04g lithium acetate (analytical pure) and 2.81g aluminum nitrate (analytical pure) ), 0.125g lauric acid (analytical purity) and 0.44g citric acid (analytical purity), respectively dissolved in 8ml of absolute ethanol. Add the ethanol solution of lithium acetate dropwise to the ethanol solution of tetrabutyl titanate, mix uniformly under magnetic stirring, and react for about 10 minutes. Then add the ethanol solution of aluminum nitrate to the mixed solution and wait for about 10 minutes to react. The ethanol solution of citric acid and lauric acid was added to the solution in sequence, and reacted for about 20 hours at room temperature to obtain a uniform milky white gel. The gel was aged in the air for 24 hours, and dried in an oven at 120°C to obtain a pale yellow precursor. Put the precursor into a ball mill tank, add an appropriate amount of agate balls, and ball mill on a ball mill at a speed of 400r/min for 2 hours to obtain superfine precursor powder. The powder is placed in a tube furnace under an argon atmosphere, and the temperature is increased to 500°C for 2 hours at a heating rate of 180°C/hour to preliminarily decompose the raw materials. After the temperature drops to 20-50°C, the temperature is increased at 150°C/hour Increase the temperature to 800℃ for 15 hours at a constant rate to obtain Li coated carbon 4 Al 0.15 Ti 4.85 O 12. Figure 5 Shown as Li 4 Al 0.15 Ti 4.85 O 12 XRD pattern. The position and relative intensity of each diffraction peak of the XRD pattern of the synthesized product are all the same as those of Li 4 Ti 5 O 12 The standard cards match, without any miscellaneous phases. It shows that after doping with aluminum and coating a small amount of carbon, Li with high crystallinity can still be obtained 4 Ti 5 O 12.

[0024] Example 3

[0025] Synthesis of 0.05mol LiFeTiO 3 , Weigh 17g of tetrabutyl titanate (analytical pure), 5.1g of lithium acetate (analytical pure), 20.2g of ferric nitrate (analytical pure), 2.9g of ethylenediaminetetraacetic acid (analytical pure) and 2.5g of oxalic acid (analytical grade) was dissolved in 12ml of absolute ethanol. Slowly add the ethanol solution of lithium acetate dropwise to the ethanol solution of tetrabutyl titanate, mix well under magnetic stirring, and react for about 10 minutes. Then slowly add the ethanol solution of ferric nitrate to the mixed solution and wait for 15 minutes to react. Then, add the ethanol solution of ethylenediaminetetraacetic acid and oxalic acid to the solution in sequence, and react for about 22 hours at room temperature to obtain a uniform milky white gel. The gel was aged in the air for 10 hours, and dried in an oven at 100°C to obtain a pale yellow precursor. Put the precursor into the ball milling tank, add an appropriate amount of agate balls, and ball mill on a ball mill at a speed of 300r/min for 1.5 hours to obtain ultrafine precursor powder. Put the powder in a muffle furnace and raise the temperature to 800℃ for 10 hours at a heating rate of 200℃/hour to obtain LiFeTiO with spinel structure 3.