Lithium titanate battery material, method for preparing same, and use thereof

Abstract

The application provides a lithium titanate battery material, a preparation method and application thereof. The preparation method comprises the following steps: mixing part of a titanium source and a lithium source, and performing ball milling to obtain initial ball milling products; mixing the initial ball milling products with the remaining titanium source, and continuing to perform ball milling to obtain ball milling products; and sequentially performing drying, calcining and screening on the ball milling products to obtain the lithium titanate battery material. By adding the titanium source in batches in the ball milling process, a part of the titanium source is attached to the ball milling particles, which can effectively reduce the volatilization of lithium during high-temperature calcining in the later stage, and can form TiO2 on the surface of the lithium titanate after calcining, thereby playing the role of a conductive agent, and further inhibiting the polarization of the electrode due to high current, and making up for the deficiency of the lithium titanate material. The method is helpful to improve the utilization rate of the lithium source, improve the conductive performance of the lithium titanate sample, improve the stability and production efficiency of the product.

Description

Technical Field

[0001] The present invention relates to the field of lithium-ion battery materials, and in particular to a lithium titanate battery material, a preparation method thereof, and applications thereof. Background Art

[0002] Lithium titanate batteries primarily consist of a positive electrode (currently available in lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, and ternary materials), a negative electrode (lithium titanate), an electrolyte capable of transferring lithium ions, and a separator that separates the positive and negative electrodes. Their function is primarily accomplished by continuously converting between lithium-poor and lithium-rich states.

[0003] Lithium titanate (LTO) is a crucial component of LTO batteries. Currently, LTO battery materials suffer from defects in their crystal structure due to the volatilization of lithium sources during sintering. This results in low phase purity and poor conductivity. Therefore, improving the LTO sintering process has become a critical issue. Summary of the Invention

[0004] The main purpose of the present invention is to provide a lithium titanate battery material, a preparation method and application thereof, so as to improve the problem in the prior art that lithium source volatilization during sintering causes defects in the lithium titanate crystal structure.

[0005] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, a method for preparing a lithium titanate battery material is provided, which comprises: mixing a portion of a titanium source and a lithium source and then ball-milling the mixture to obtain a primary ball-milled product; mixing the primary ball-milled product with the remaining titanium source and continuing to ball-mill the mixture to obtain a ball-milled product; and drying, calcining and sieving the ball-milled product in sequence to obtain a lithium titanate battery material.

[0006] Furthermore, the mixing mass ratio of the partial titanium source and the lithium source is 1:0.43 to 1:0.54; the titanium source is preferably selected from TiO2 and / or metatitanic acid; and the lithium source is preferably selected from any one or more of LiOH·H2O and lithium carbonate.

[0007] Furthermore, the mass ratio of the partial titanium source to the remaining titanium source is 1:0.03 to 1:0.13.

[0008] Furthermore, mixing part of the titanium source and the lithium source and then ball-milling to obtain a primary ball-milled product includes: adding part of the titanium source and the lithium source into a container filled with deionized water and stirring and dispersing them to obtain a dispersion; preferably, the stirring speed is 1750-3500 r / min, and the stirring time is 2.5-4h, and the dispersion is added to a ball mill filled with grinding balls for ball milling to obtain a primary ball-milled product; preferably, the speed of the ball mill is 3200-3800 r / min, and the ball milling time is 1.5-2.5h.

[0009] Furthermore, the primary ball-milled product is mixed with the remaining titanium source and then ball-milled to obtain a ball-milled product, which includes: mixing the primary ball-milled product with the pre-dissolved remaining titanium source and a solvent and ball-milling the mixture to obtain a ball-milled product; the preferred solvent is selected from ethylene glycol, methanol, anhydrous ethanol or isopropanol; and the preferred amount of solvent added is 50 to 150 g.

[0010] Furthermore, in the steps of drying, calcining and screening the ball milled product in sequence, the drying is carried out by spray drying, preferably the spray drying temperature is 110 to 205° C., and the spray flow rate during the spray drying process is 5 to 7 m 3 / h; preferably, the calcination is carried out by batch sintering, preferably the sintering temperature is 650-900 ° C, and the time is 180-360 min; more preferably, the temperature is raised to the sintering temperature at a rate of 8-12 ° C / min; preferably, after the calcined product is cooled, a screening step is performed, and more preferably, the particle size D of the lithium titanate battery material obtained after screening is 90 9~10μm, preferably D 99 It is 14 to 15 μm.

[0011] According to a second aspect of the present application, a lithium titanate battery material prepared by any of the above-mentioned preparation methods is provided.

[0012] According to a third aspect of the present application, a lithium titanate battery material is provided, wherein the phase purity of the lithium titanate battery material is 100%.

[0013] Furthermore, the particle size D of the lithium titanate battery material 90 9~10μm, preferably D 99 Preferably, the specific surface area of ​​the lithium titanate battery material is 92 to 97 m 2 / g; preferably, the gram capacity of the lithium titanate battery material is 165.4~166.4mAh / g.

[0014] According to a fourth aspect of the present application, a lithium titanate battery negative electrode sheet is provided, wherein the lithium titanate battery negative electrode sheet comprises any one of the above-mentioned lithium titanate battery materials.

[0015] According to a fifth aspect of the present application, a lithium-ion battery is provided, comprising a positive electrode, a negative electrode, an electrolyte, and a separator arranged between the positive electrode and the negative electrode, wherein the negative electrode is any one of the above-mentioned negative electrode sheets of the lithium titanate battery.

[0016] The technical solution of the present invention is applied. This preparation method adds the titanium source in batches during the ball milling process, so that a portion of the titanium source adheres to the ball-milled particles (i.e., titanium is coated on the outer layer of lithium). This not only effectively reduces the volatilization of lithium during the later high-temperature calcination, but also forms TiO2 on the surface of the lithium titanate after calcination, acting as a conductive agent, thereby inhibiting the polarization of the electrode caused by high current, thereby compensating for the shortcomings of the lithium titanate material. This method helps to improve the utilization rate of the lithium source and the conductive properties of the lithium titanate sample, and has a significant effect on ensuring the product stability and production efficiency of industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0018] Figure 1 This is a schematic flow chart of a method for preparing a lithium titanate electrode material according to a preferred embodiment of the present invention;

[0019] Figure 2 This is the electron microscope structure diagram of the ball-milled product of the comparative example;

[0020] Figure 3 This is an electron microscope structure diagram of the ball-milled product of Example 1 of the present invention;

[0021] Figure 4 This is an electron microscope structure diagram of the lithium titanate finished product of the comparative example;

[0022] Figure 5 This is an electron microscope structural diagram of the lithium titanate product of Example 1 of the present invention;

[0023] Figure 6 and Figure 7 The XRD structures of Examples 1 to 17 of the present invention and a comparative example are shown. DETAILED DESCRIPTION

[0024] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the embodiments.

[0025] As mentioned in the background, due to the volatilization of lithium source during sintering of raw materials in the prior art lithium titanate battery material, defects are generated in the crystal structure of lithium titanate, the phase purity of the obtained lithium titanate material is low, and the conductivity cannot be guaranteed. Therefore, in order to improve the above defects of lithium titanate, the present application improves the sintering process and provides a preparation method of lithium titanate battery material. The preparation method comprises: mixing part of titanium source and lithium source and then ball milling to obtain initial ball milling product; mixing the initial ball milling product with the remaining titanium source and then continuing to ball mill to obtain ball milling product; and sequentially drying, calcining and screening the ball milling product to obtain lithium titanate battery material.

[0026] The above preparation method can effectively reduce the volatilization of lithium during high-temperature calcination by adding titanium source in batches in the ball milling process, so that part of the titanium source adheres to the ball milling particles (i.e. titanium is coated on the outer layer of lithium). Moreover, TiO2 can be formed on the surface of lithium titanate after calcination, which plays the role of conductive agent, and further inhibits the polarization of the electrode due to high current, thereby making up for the deficiency of lithium titanate material. This method helps to improve the utilization rate of lithium source and improve the conductivity of lithium titanate sample, and has obvious improvement effect on ensuring the stability and production efficiency of the product in industrial production.

[0027] In the above preparation method, the raw materials of titanium source and lithium source can be the existing raw materials. In the present application, the titanium source includes but is not limited to TiO2, metatitanic acid; the lithium source includes but is not limited to LiOH·H2O, lithium carbonate. The specific amount of the part of titanium source mixed with lithium source is not particularly limited, as long as part of the titanium source is added later to realize the batch addition of titanium source, so that part of the titanium source adheres to the surface of the ball milling particles, which helps to reduce the volatilization of lithium in the subsequent calcination process. In order to make the titanium source adhere to the ball milling particles more effectively and comprehensively, more effectively reduce the volatilization of lithium in the calcination process, and form TiO2 on the surface of lithium titanate to improve the conductivity of lithium titanate electrode material. In a preferred embodiment, the mass ratio of the part of titanium source and lithium source is 1:0.43-1:0.54, preferably 1:0.45-1:0.50. In another preferred embodiment, the mass ratio of the part of titanium source to the remaining titanium source is 1:0.03-1:0.13.

[0028] The specific conditions in the above ball milling step can be reasonably adjusted according to the actual situation. In a preferred embodiment of the present application, the ball milling of the part of titanium source and lithium source to obtain the initial ball milling product comprises: adding the part of titanium source and lithium source into a container containing deionized water and stirring to disperse to obtain a dispersion liquid; preferably, the stirring speed is 1750-3500 r / min, and the stirring time is 2.5-4 h; adding the dispersion liquid into a ball mill containing grinding balls to ball mill to obtain the initial ball milling product; preferably, the speed of the ball mill is 3200-3800 r / min, and the ball milling time is 1.5-2.5 h.

[0029] The aforementioned process of mixing the initially milled material with the remaining titanium source and then continuing to ball mill to obtain a ball-milled product comprises mixing the initially milled material with the pre-dissolved remaining titanium source and a solvent to obtain a ball-milled product; the solvent is preferably selected from methanol, anhydrous ethanol, or isopropanol; the preferred amount of solvent added is 50 to 150 g, preferably 80 to 120 g. The aforementioned solvent acts as a dispersant, reducing the molecular forces between the milled materials and improving milling efficiency. Adding the titanium source and solvent to the surface of the particles after the initial ball milling allows a portion of the titanium source to adhere to the surface of the lithium source. The amount of solvent used is determined based on the amount of the portion of the titanium source used.

[0030] In the above-mentioned steps of drying, calcining and screening the ball milled product in sequence, the drying is carried out by spray drying, preferably the spray drying temperature is 110 to 205°C, and the spray flow rate during the spray drying process is 5 to 7m 3 / h; preferably, calcination adopts batch sintering, preferably the sintering temperature is 650-900 ° C, preferably 700-820 ° C, the time is 180-360 min, preferably 180-270 min; preferably, the temperature is raised to the sintering temperature at a rate of 8-12 ° C / min, more preferably at a rate of 10 ° C / min; preferably, after the calcined product is cooled, a screening step is performed, and more preferably, the particle size D of the lithium titanate battery material obtained after screening is 90 9~10μm, D 99 It is 14 to 15 μm.

[0031] Spray drying involves atomizing a thin material and then rapidly vaporizing the water upon contact with hot air, resulting in a dry product. This process can directly dry a liquid into a powder or granular form. Spray drying typically involves a spray dryer mechanically dispersing the slurry into a mist of particles, which increases the surface area for water evaporation and accelerates the drying process. Upon contact with the hot air, the majority of the water is instantly removed. Controlling the drying temperature and flow rate within the above ranges can achieve rapid drying.

[0032] The sintering temperature and time are controlled within the above ranges to ensure that the particles have a good particle size distribution and a high specific surface area. The temperature can be quickly raised to the target sintering temperature according to the above heating rate. Batch sintering is preferably carried out in a muffle furnace. After sintering, it is naturally cooled to a room temperature. After cooling, the lithium titanate product can be obtained by screening. The specific particle size

[0033] In a second typical embodiment of the present application, a lithium titanate battery material prepared by any of the above-mentioned preparation methods is provided. Compared with the traditional hydrothermal method and sol-gel method, this method is easier to quantify and has more stable performance.

[0034] In a third exemplary embodiment, a lithium titanate battery material is provided, wherein the phase purity of the lithium titanate battery material is 100%. The lithium titanate battery material has a more excellent conductivity and significantly improves the stability and production efficiency of industrialized production.

[0035] In a preferred embodiment, the particle size D of the lithium titanate battery material is 90 9 to 10 μm, more preferably D 99 Preferably, the specific surface area of ​​the lithium titanate battery material is 92 to 97 m 2 / g; preferably, the gram capacity of the lithium titanate battery material is 165.4-166.4 mAh / g. The above performances of the lithium titanate battery material provided in this application are significantly improved compared with the prior art.

[0036] In a fourth typical embodiment, a lithium titanate battery negative electrode sheet is provided, and the lithium titanate battery negative electrode sheet includes any of the above-mentioned lithium titanate battery materials.

[0037] In a fifth typical embodiment, a lithium-ion battery is provided, comprising a positive electrode, a negative electrode, an electrolyte, and a separator disposed between the positive electrode and the negative electrode, wherein the negative electrode is any of the above-mentioned lithium titanate battery materials.

[0038] The following will further illustrate the beneficial effects of the present application with reference to specific examples. Figure 1 It should be noted that the titanium source in the following examples is TiO2 and the lithium source is LiOH·H2O.

[0039] Experimental Example 1

[0040] 1) Weighing

[0041] In a dry environment, accurately weigh 302 g of lithium source, 649 g of titanium source, and 50 g of titanium source (mass ratio is 1:0.08);

[0042] 2) Premix

[0043] Place 4.45 kg of deionized water in a barrel, add 302 g of lithium source and 649 g of titanium source (mass ratio 0.47:1) during stirring, maintain the speed at 1750 r / min, and disperse for 4 hours;

[0044] 3) Ball milling

[0045] After cleaning the ball mill, add 1770g of zirconium balls and then transfer the dispersed slurry to the dispersion tank. Maintain the speed at 3500rpm and grind for 2h. Then add 50g of pre-dissolved titanium source and 95g of ethylene glycol and continue grinding. After grinding, transfer the slurry to the feed pipe. Figure 3The electron microscope structure after ball milling is shown.

[0046] 4) Spray drying

[0047] Clean the spray dryer before each spray drying, set the inlet air temperature at 205℃, the exhaust air temperature at around 110℃, maintain the pump speed at 28, and adjust the flow rate to 6m 3 / h, and start spray drying after the spray dryer parameters are stable.

[0048] 5) Calcination

[0049] Batch sintering was performed in a muffle furnace at a heating rate of 10°C / min to the target sintering temperature of 750°C, followed by a holding time of 180 min and then natural cooling to room temperature.

[0050] 6) Screening

[0051] After the sample is cooled, it is sieved to obtain the finished lithium titanate product, wherein: Figure 5 The electron microscope structure of the finished lithium titanate product is shown.

[0052] Experimental Example 2

[0053] 1) Weighing

[0054] In a dry environment, accurately weigh 302 g of lithium source, 659 g of titanium source, and 40 g of titanium source (mass ratio is 1:0.06);

[0055] 2) Premix

[0056] 4.45 kg of deionized water was placed in a barrel, and 302 g of lithium source and 659 g of titanium source (mass ratio of 0.46:1) were added during stirring. The speed was maintained at 1750 r / min and the mixture was dispersed for 4 h.

[0057] 3) Ball milling

[0058] After cleaning the ball mill, add 1770g of zirconium balls first, transfer the dispersed slurry to the dispersion tank, add; maintain the speed at 3450rpm, grind for 2h, add 40g of pre-dissolved titanium source and 95g of ethylene glycol and continue grinding; after grinding, transfer the slurry to the material pipe.

[0059] 4) Spray drying

[0060] Clean the spray dryer before each spray drying, set the inlet air temperature at 205℃, the exhaust air temperature at around 110℃, maintain the pump speed at 28rpm / min, and adjust the flow rate to 6m 3 / h, and start spray drying after the spray dryer parameters are stable.

[0061] 5) Calcination

[0062] Batch sintering was performed in a muffle furnace at a heating rate of 10°C / min to the target sintering temperature of 820°C, followed by a holding time of 180 min and natural cooling to room temperature.

[0063] 6) Screening

[0064] After the sample is cooled, it is sieved to obtain the finished lithium titanate product.

[0065] Example 3

[0066] The only difference from Example 1 is: weighing 302g lithium source, 664g titanium source (the mass ratio of titanium source to lithium source added for the first time is 1:0.45), and 35g titanium source (added for the second time) (the mass ratio of the first to the second time is 1:0.05).

[0067] Example 4

[0068] The only difference from Example 1 is: weighing 302g lithium source, 669g titanium source (mass ratio of titanium source to lithium source added for the first time: 1:0.45), and 30g titanium source (added for the second time) (mass ratio is 1:0.05).

[0069] Example 5

[0070] The only difference from Example 1 is: 302 g of lithium source, 679 g of titanium source (mass ratio of titanium source to lithium source added for the first time: 1:0.44), and 20 g of titanium source (added for the second time) (mass ratio is 1:0.03) are weighed.

[0071] Example 6

[0072] The only difference from Example 1 is: 302 g lithium source, 689 g titanium source (mass ratio of titanium source to lithium source added for the first time: 1:0.44), and 10 g titanium source (added for the second time) (mass ratio is 1:0.01) are weighed.

[0073] Example 7

[0074] The only difference from Example 1 is: 302 g lithium source, 694 g titanium source (mass ratio of titanium source to lithium source added for the first time: 1:0.44), and 5 g titanium source (added for the second time) (mass ratio is 1:0.007) are weighed.

[0075] Example 8

[0076] The only difference from Example 1 is: 302 g lithium source, 639 g titanium source (mass ratio of titanium source to lithium source added for the first time: 1:0.47), and 60 g titanium source (mass ratio of the second time added) are weighed (mass ratio is 1:0.09).

[0077] Example 9

[0078] The only difference from Example 1 is: 302 g of lithium source, 619 g of titanium source (mass ratio of titanium source to lithium source added for the first time: 1:0.49), and 80 g of titanium source (mass ratio of the second time added) are weighed (mass ratio is 1:0.13).

[0079] Example 10

[0080] The only difference from Example 1 is: 302 g lithium source, 599 g titanium source (mass ratio of titanium source to lithium source added for the first time: 1:0.50), and 100 g titanium source (mass ratio of the second addition is 1:0.17) are weighed.

[0081] Example 11

[0082] The only difference from Example 1 is that the rotation speed of the ball mill is 3200 r / min and the ball milling time is 2.5 h.

[0083] Example 12

[0084] The only difference from Example 1 is that the rotation speed of the ball mill is 3800 r / min and the ball milling time is 1.5 h.

[0085] Example 13

[0086] The only difference from Example 1 is that the rotation speed of the ball mill is 2800 r / min and the ball milling time is 3 h.

[0087] Example 14

[0088] The only difference from Example 1 is that the stirring speed during dispersion is 1800 r / min, the stirring time is 3.5 h, and the solvent for the second addition of the titanium source is ethylene glycol, with an addition amount of 50 g.

[0089] Example 15

[0090] The only difference from Example 1 is that the stirring speed during dispersion is 1850 r / min, the stirring time is 2.5 h, and the solvent for the second addition of the titanium source is methanol, with an addition amount of 150 g.

[0091] Example 16

[0092] The only difference from Example 1 is that the temperature is raised to the target sintering temperature of 650° C. at a heating rate of 8° C. / min, and the sintering time is 360 min.

[0093] Example 17

[0094] The only difference from Example 1 is that the temperature is raised to the target sintering temperature of 900° C. at a heating rate of 12° C. / min, and the sintering time is 180 min.

[0095] Comparative Example (Traditional Process)

[0096] 1) Weighing

[0097] Accurately weigh 302 g of lithium source and 699 g of titanium source in a dry environment;

[0098] 2) Pre-mixing

[0099] Put 4.45 Kg of deionized water into the barrel, and add 302 g of lithium source and 699 g of titanium source during stirring, keep the stirring speed at 1750 r / min, and disperse for 4 h;

[0100] 3) Ball milling

[0101] After cleaning the ball mill, first add 1770 g of zirconium balls, transfer the dispersed slurry to the dispersion cylinder, and add; keep the stirring speed at 3450 rpm, and grind for 2 h; after grinding, transfer the slurry to the pipe. Among them, Figure 2 shows the electron microscope structure diagram of the sample after ball milling of the comparative example.

[0102] 4) Spray drying

[0103] Clean the spray dryer before each spray drying, set the inlet temperature to 205℃, control the exhaust temperature at about 110℃, keep the pump speed at 28 rpm / min, and adjust the flow to 6 m 3 / h, and start spray drying after the spray dryer parameters are stable.

[0104] 5) Calcination

[0105] Batch sintering was performed using a muffle furnace, the temperature was raised to the target sintering temperature of 820℃ at a rate of 10℃ / min, and then the holding time was 180 min. Naturally cool to room temperature.

[0106] 6) Screening

[0107] After the sample is cooled, the lithium titanate product is screened. Among them, Figure 4 shows the electron microscope structure diagram of the product.

[0108] Detection:

[0109] The lithium titanate products prepared in the above examples and comparative examples were detected from the aspects of electron microscope structure, particle size, specific surface area, phase ratio, and specific capacity. Among them, the particle size distribution was determined by a laser particle size instrument, the specific surface area was determined by the BET method, the phase structure and phase purity ratio were determined by XRD (see Figure 6 and Figure 7 , where the vertical lines on the abscissa are standard cards, Figure 6 from bottom to top are the comparative example and examples 1-9, Figure 7The comparative example and the examples 10-17 are in turn from bottom to top. The comparative example has a slight impurity peak at the position of 28 indicated by the arrow. When the purity reaches about 99.90%, the specific purity value can be calculated by the instrument, but the XRD pattern cannot show the difference, so the XRD patterns of all examples are the same. The capacity is prepared by stirring the lithium titanate material with the superconducting carbon black binder to form a negative electrode sheet, and the lithium ion battery is formed with a metal lithium sheet positive electrode sheet and a 1M LiPF6-EC / DMC (volume ratio 1:1) electrolyte, and the lithium ion battery is assembled in an argon-filled glove box to measure the button cell.

[0110] The specific test results are shown in Tables 1-3 below.

[0111] Table 1: Particle size comparison of different processes

[0112]

[0113]

[0114] Table 2: Relationship between different processes and specific surface area, phase purity after sintering and capacity

[0115]

[0116]

[0117] Table 3: Rate data of batteries at room temperature of different processes

[0118] Rate capability 5C charge / % 5C discharge / % 10C charge / % 10C discharge / % Comparative Example (conventional process) 96.89 94.59 92.47 92.68 Example 1 97.15 95.61 93.26 93.35 Example 2 97.13 95.62 93.68 93.33 Example 3 97.25 96.59 93.48 93.21 Example 4 96.98 95.49 93.25 93.26 Example 5 96.99 95.19 93.15 93.34 Example 6 96.95 94.64 93.08 93.02 Example 7 96.92 94.61 93.05 92.71 Example 8 97.14 96.15 93.33 93.28 Example 9 97.16 96.25 93.28 92.86 Example 10 96.94 96.18 92.97 92.76 Example 11 96.98 96.24 93.16 93.24 Example 12 97.16 96.34 93.24 93.17 Example 13 97.18 96.28 93.58 93.17 Example 14 97.25 96.28 93.26 93.16 Example 15 97.16 95.67 93.54 93.24 Example 16 97.19 95.89 93.24 93.25 Example 17 97.02 95.48 93.16 93.22

[0119] As can be seen from the above examples, by improving the preparation process of the raw material for preparing lithium titanate and reasonably adjusting the amount of titanium source added in batches, the volatilization of lithium in the calcination process is realized, the defects of the finished product are reduced, the phase ratio can reach 100%, and the surface of the calcined lithium titanate is formed TiO2, which improves the conductivity of lithium titanate as an electrode material. The stability and production efficiency of the subsequent lithium titanate negative electrode sheet and lithium ion battery industrial production are improved.

[0120] The present application can be applied to the preparation of lithium titanate negative material, but is not limited to this field, based on the same principle, it can also be applied to the field of lithium iron phosphate, lithium manganate and other batteries.

[0121] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a lithium titanate battery material, characterized in that: The preparation method comprises: Part of the titanium source and the lithium source are mixed and ball-milled to obtain a primary ball-milled product; The initially ball-milled product is mixed with the remaining titanium source and then ball-milled to obtain a ball-milled product; The ball-milled product is dried, calcined, and sieved in sequence to obtain the lithium titanate battery material; Calculated by mass ratio, the mixing mass ratio of the part of the titanium source and the lithium source is 1:0.43 to 1:0.54; The mass ratio of the part of the titanium source to the remaining titanium source is 1:0.03 to 1:0.

13.

2. The preparation method according to claim 1, characterized in that The titanium source is selected from TiO2 and / or metatitanic acid; The lithium source is selected from any one or more of LiOH·H2O and lithium carbonate.

3. The preparation method according to claim 1, characterized in that A portion of the titanium source and the lithium source are mixed and ball-milled to obtain a primary ball-milled product comprising: adding the portion of the titanium source and the lithium source into a container containing deionized water, stirring and dispersing the mixture to obtain a dispersion; The dispersion is added into a ball mill containing grinding balls for ball milling to obtain the primary ball-milled product.

4. The preparation method according to claim 3, characterized in that The stirring speed is 1750 ~3500 r / min, and the stirring time is 2.5~4h.

5. The preparation method according to claim 3, characterized in that The rotation speed of the ball mill is 3200-3800 r / min, and the ball milling time is 1.5-2.5 h.

6. The preparation method according to claim 3, characterized in that The initially milled product is mixed with the remaining titanium source and then ball milled to obtain a ball milled product comprising: The primary ball-milled product is mixed with the pre-dissolved remaining titanium source and solvent and ball-milled to obtain the ball-milled product.

7. The preparation method according to claim 6, characterized in that The solvent is selected from ethylene glycol, methanol, anhydrous ethanol or isopropanol.

8. The preparation method according to claim 6, characterized in that The amount of the solvent added is 50-150 g.

9. The preparation method according to claim 1, characterized in that The ball milled product is dried, calcined and sieved in sequence, wherein the drying is performed by spray drying, the temperature of the spray drying is 110-205°C, and the flow rate of the spray during the spray drying process is 5-7m 3 / h.

10. The preparation method according to claim 9, characterized in that The calcination is carried out by batch sintering, the sintering temperature is 650-900° C., and the sintering time is 180-360 min.

11. The preparation method according to claim 10, characterized in that: The temperature was raised to the sintering temperature at a heating rate of 8-12°C / min.

12. The preparation method according to claim 9, characterized in that After the calcined product is cooled, the screening step is performed.

13. The preparation method according to claim 12, characterized in that The particle size D of the lithium titanate battery material obtained after screening 90 9~10μm.

14. The preparation method according to claim 12, characterized in that The particle size D of the lithium titanate battery material obtained after screening 99 14~15μm.

15. The lithium titanate battery material prepared by the preparation method according to any one of claims 1 to 14.

16. The lithium titanate battery material according to claim 15, characterized in that: The phase purity of the lithium titanate battery material is 100%.

17. The lithium titanate battery material according to claim 16, characterized in that: The particle size D of the lithium titanate battery material 90 9~10μm.

18. The lithium titanate battery material according to claim 16, characterized in that The particle size D of the lithium titanate battery material 99 14~15μm.

19. The lithium titanate battery material according to claim 16, characterized in that The specific surface area of ​​the lithium titanate battery material is 92~97m 2 / g.

20. The lithium titanate battery material according to claim 16, characterized in that The gram capacity of lithium titanate battery material is 165.4~166.4mAh / g.

21. A negative electrode sheet for a lithium titanate battery, characterized in that: The lithium titanate battery negative electrode sheet comprises the lithium titanate battery material according to any one of claims 15 to 20.

22. A lithium-ion battery comprising a positive electrode, a negative electrode, an electrolyte, and a separator disposed between the positive electrode and the negative electrode, characterized in that: The negative electrode is the negative electrode sheet of the lithium titanate battery according to claim 21.

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