CN-121976280-A - Modified lithium titanate material, preparation method and application thereof

CN121976280ACN 121976280 ACN121976280 ACN 121976280ACN-121976280-A

Abstract

The application discloses a modified lithium titanate material, a preparation method and application thereof, wherein the preparation method comprises the steps of S100, ball milling a titanium source and a lithium source to prepare first powder, S200, heating the first powder to perform a first solid-phase reaction to prepare a first precursor comprising lithium titanate crystal nucleus, S300, densification processing the first precursor to obtain a block-shaped second precursor, heating the second precursor to perform a second solid-phase reaction to prepare a block-shaped third precursor comprising single-crystal lithium titanate, and S400, mechanically crushing the third precursor to prepare the modified lithium titanate material. The modified lithium titanate material is monocrystalline lithium titanate particles, so that the use stability and the use safety of the lithium ion battery are enhanced, and the modified lithium titanate material has low porosity, thereby being beneficial to improving the energy density of the lithium ion battery. The modified lithium titanate material with high thermal stability is beneficial to enhancing the use safety and the use stability of the lithium ion battery under the high-temperature working condition.

Inventors

CHENG SHUHAO
JIAO YUZHI
QIN JUN
WANG LUYANG
SHI RUMEI
JIN LIPING
SHAO QIWEI

Assignees

台州闪能科技有限公司

Dates

Publication Date: 20260505
Application Date: 20260209

Claims (10)

1. The preparation method of the modified lithium titanate material is characterized by comprising the following steps: s100, ball milling a titanium source and a lithium source to prepare first powder; s200, heating to perform a first solid phase reaction on the first powder to obtain a first precursor comprising lithium titanate crystal nucleus; S300, performing densification treatment on the first precursor to obtain a blocky second precursor, and heating to perform a second solid-phase reaction on the second precursor to obtain a blocky third precursor comprising single-crystal lithium titanate; S400, mechanically crushing the third precursor to obtain the modified lithium titanate material.
2. The preparation method according to claim 1, wherein at least one of the following conditions is satisfied: The mole number of the lithium element in the lithium source is n 1 , and the mole number of the titanium element in the titanium source is n 2 ,n 1 ：n 2 = (0.8-1.0): 1; the lithium source is one or more of lithium carbonate, lithium hydroxide or lithium acetate; the titanium source is titanium dioxide; The porosity of the modified lithium titanate material is less than or equal to 2%, the specific surface area is less than or equal to 4m 2 /g, and the particle size is 5-20 mu m.
3. The method according to claim 1, wherein the step S100 comprises the sub-steps of: S110, ball milling a titanium source, a lithium source and a mineralizer by a wet method to prepare ball milling slurry, wherein the mineralizer is one or more of lithium chloride and lithium fluoride; S120, performing pressure type spray drying on the ball milling slurry, wherein the air flow pressure of the spray drying is 0.5-1.2 MPa, and the first powder with the D50 particle size of 5-15 μm is prepared.
4. A method of preparation according to claim 3, wherein at least one of the following conditions is met: in the step S110, the total mass of the titanium source and the lithium source is m 1 , and the mass of the mineralizer is m 2 ,m 1 ：m 2 = (60-200): 1; in the step S110, the ball milling medium used in the wet ball milling is one or more of zirconia microbeads, alumina microbeads, zirconium silicate microbeads, silicon nitride microbeads and stainless steel microbeads; the size of the ball milling medium is 0.2 mm-0.5 mm; The solid content in the ball milling slurry is 20% -50%; The ball-material ratio of the wet ball milling treatment is (1-10) 1, the ball milling rotating speed is 100-500 rpm, and the ball milling time is 1-10 h.
5. The preparation method according to claim 1, wherein at least one of the following conditions is satisfied: The time of the first solid phase reaction is 5-12 hours, the temperature of the first solid phase reaction is 500-700 ℃, the temperature rising rate is 1-7 ℃ per minute, and the reaction atmosphere of the first solid phase reaction is air and/or inert gas; the time of the second solid phase reaction is 1-10 h, the temperature of the second solid phase reaction is 750-900 ℃, the temperature rising rate is 2-8 ℃ per minute, and the reaction atmosphere of the second solid phase reaction is inert gas.
6. The method according to claim 1, wherein the step S300 comprises the sub-steps of: S310, applying pressure to the first precursor to prepare a block-shaped second precursor, wherein the pressure is 15-35 MPa, the length of the second precursor is 200-400 mm, the width of the second precursor is 200-400 mm, and the height of the second precursor is 50-150 mm; and S320, heating to perform a second solid phase reaction on the second precursor to obtain a blocky third precursor comprising single crystal lithium titanate.
7. The method according to claim 1, wherein the step S400 is to mechanically crush the third precursor by a pair of rollers, and then vibration-screen the third precursor to obtain the modified lithium titanate material, wherein the roller spacing of the pair of rollers is 0.1 mm-0.5 mm, the mesh number of the vibration-screened mesh is 800-3000 mesh, and the particle size of the modified lithium titanate material is 5-20 μm.
8. The modified lithium titanate material is characterized in that the modified lithium titanate material is monocrystalline lithium titanate particles, the porosity of the modified lithium titanate material is less than or equal to 2%, the specific surface area is less than or equal to 4m 2 /g, and the particle size is 5-20 mu m.
9. The modified lithium titanate material of claim 8 or the modified lithium titanate material prepared by the preparation method of any one of claims 1-7 is used as a negative electrode material in a lithium ion battery.
10. A lithium ion battery is characterized in that a negative electrode material in the lithium ion battery comprises the modified lithium titanate material disclosed in claim 8 or the modified lithium titanate material prepared by the preparation method disclosed in any one of claims 1-7, the lithium ion battery is subjected to constant current charge and discharge at the rate of 0.5 ℃ at the temperature of 90 ℃, and the 100-cycle retention rate of the lithium ion battery is more than or equal to 90%.

Description

Modified lithium titanate material, preparation method and application thereof Technical Field The application relates to the technical field of lithium ion batteries, in particular to a modified lithium titanate material, a preparation method and application thereof. Background At present, lithium ion batteries are widely used as high-efficiency energy storage devices in the fields of electric automobiles, portable electronic equipment, renewable energy storage and the like. In order to further increase the application range of the lithium ion battery, the continuous increase of the energy density is the core direction of research and development in the industry. The negative electrode material is used as a key component in the lithium ion battery, and directly influences the energy storage capacity, the charging speed, the service life and the safety of the lithium ion battery, so that the performance breakthrough of the negative electrode material is a great key factor for improving the service performance of the lithium ion battery. It is worth mentioning that most commercial lithium ion batteries are low in use stability and poor in safety under high-temperature working conditions at present. For example, when the use temperature of a lithium ion battery exceeds 90 ℃, a series of fatal chain reactions occur inside the conventional liquid lithium ion battery. First, a solid electrolyte interface film protecting the surface of a negative electrode material in a lithium ion battery starts to decompose, and the negative electrode material having high chemical activity is directly exposed to an electrolyte to consume active lithium. The heat released in the decomposition reaction of the solid electrolyte interface film increases the internal temperature of the battery, so that the decomposition reaction of the solid electrolyte interface film is more severe, and the severe decomposition reaction increases the internal temperature of the battery rapidly again, thereby generating vicious circle. Secondly, when the service temperature of the lithium ion battery reaches 130-180 ℃, the sharply-increased temperature melts the polymer diaphragm between the anode and the cathode, so that the anode and the cathode materials directly generate physical contact, the internal resistance of the battery is suddenly reduced, the current is suddenly increased, and the temperature is sharply increased, thereby causing internal short circuit phenomenon. Furthermore, common ternary materials (NCM) decompose and release oxygen at 180 to 220 ℃, which undergoes a severe oxidation reaction with the electrolyte, releasing a lot of heat. Finally, carbonate electrolytes decompose to produce combustible gases at high temperatures, whereas the usual polyvinylidene fluoride binders react strongly exothermically with lithium metal at temperatures exceeding 200 ℃. The industrial industry aims to improve the use stability of the lithium ion battery in high-temperature working conditions, and breakthrough is mainly sought from the two directions of strengthening external heat management, namely maintaining the working temperature of the lithium ion battery in a safe window (usually below 45 ℃) through external systems such as liquid cooling, air cooling, phase change materials and the like. But in the high temperature working condition of 90 ℃, the burden of the external cooling system is very heavy, and the energy consumption of the external cooling system is larger, so the feasibility is low. Secondly, the innovation of electrolyte is carried out, and the solid electrolyte technology is taken as an important innovation direction of an electrolyte system, and is generally regarded as an ideal solution of next-generation high-energy-density and high-safety energy storage devices by a person skilled in the art. However, the solid-solid interface between the solid electrolyte and the battery causes impedance problems, increasing ion transport resistance. Further, the related systems, manufacturing equipment and process standards of the solid electrolyte materials do not form a synergetic industrial chain system, and the problems of industry chain synergetic, process maturity and cost exist, so that the solid electrolyte is difficult to realize large-scale commercial application. Therefore, in order to increase the high-temperature use stability and the high-temperature use safety of the lithium titanate negative electrode material at the same time, it is needed to develop a preparation process capable of preparing the lithium titanate negative electrode material with the high-temperature use stability and the high-temperature use safety. Disclosure of Invention The application aims to provide a modified lithium titanate material, a preparation method and application thereof, which are beneficial to improving the use stability, the service life and the high-temperature use safety of the modified lithium titanate material and a lithium ion batt