Negative electrode material with titanium niobate coated with lanthanide coating as well as preparation method and application of negative electrode material

Abstract

The invention belongs to the technical field of negative electrode materials, and relates to a negative electrode material with titanium niobate coated with a lanthanide coating as well as a preparation method and application of the negative electrode material. According to the core structure design, a double-layer coating structure composed of two kinds of functional coatings is constructed on the surfaces of titanium niobate (TNO) particles, specifically, the inner layer is made of an electronic conduction type material, has high electronic conductivity and is used for enhancing the overall electronic transmission performance of the material; and the outer layer is a lithium ion conductor type material and is used for enhancing lithium ion diffusion, blocking side reaction and stabilizing an electrolyte interface. According to the double-layer structure, cooperative transmission of electrons and ions is achieved, the interface stability is improved through the chemical stability of the outer layer structure, side reactions and capacity fading in the circulation process are effectively reduced, and compared with a traditional single-layer coating or single doping method, the design has better comprehensive electrochemical performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of negative electrode materials, and relates to a lanthanide element coating coated titanium niobate negative electrode material and a preparation method and application thereof. BACKGROUND

[0002] Under the background of rapid development of science and technology today, as the most advanced energy technology, lithium batteries have become an indispensable power source for consumer electronics and electric vehicles. With the rapid growth of the battery market, scientific and technological challenges in this field are increasingly prominent, especially in the face of future electric vehicle applications, there is an urgent need to improve the energy density, cycle life and safety of existing batteries. At present, graphite negative electrodes dominate in the field of electric vehicles and grid energy storage due to their high specific capacity and low cost. However, the problems it faces during fast charging cannot be ignored, including slow interfacial kinetics and large spatial overpotential heterogeneity, which can easily cause lithium dendrite growth and abnormal formation of solid electrolyte interface (SEI) film, posing a serious threat to the safety and service life of the battery.

[0003] In order to solve the above-mentioned problems of graphite negative electrodes during fast charging, lithium titanate (LTO) emerges as a "zero stress" material. LTO has a working voltage of 1.55V (vs Li / Li + ), which can effectively inhibit the generation of lithium dendrites, thereby greatly improving the safety performance of the battery. However, the relatively low theoretical capacity of LTO leads to insufficient energy density, which is the main bottleneck limiting its commercialization. In the face of such challenges, niobium-based oxide materials have shown unique advantages and broad prospects. For example, titanium niobate not only inherits the excellent properties of LTO in cycle stability, but also has a working potential of up to 1.6V (vs Li / Li + ) and a high theoretical specific capacity of 387.6mAh g -1 , which makes it have great potential in high-power energy storage and new energy vehicles, and is considered as one of the core choices of the next generation of high-performance negative electrode materials.

[0004] However, it is worth noting that although titanium niobate has many advantages, it also has some limitations, such as low electronic conductivity, poor rate performance and serious interfacial side reactions, which limit its large-scale application. SUMMARY

[0005] The purpose of the present application is to solve the above-mentioned problems existing in the prior art, and a "inner layer conductive-outer layer stable" double-coated TNO material is constructed, and a high-performance lanthanide element coating coated titanium niobate negative electrode material is obtained by combining pulse laser deposition (PLD) technology and heat treatment technology.

[0006] The object of the present application can be achieved by the following technical solutions:

[0007] A lanthanide element coating coated titanium niobate negative electrode material, the negative electrode material comprises titanium niobate, a conductive inner layer and a stable outer layer from inside to outside, wherein at least one of the conductive inner layer and the stable outer layer contains a lanthanide element, and the conductive inner layer and the stable outer layer are prepared by pulse laser deposition, and the thickness ratio of the conductive inner layer and the stable outer layer is 1:0.5-1.5.

[0008] The present application realizes the synergistic optimization of electron and ion channels by depositing an inner electronic conductor and an outer conductor on the surface of titanium niobate (TNO) particles through the construction of a double-layer coating structure of "inner layer conductive + outer layer ion conductor", and by controlling the thickness of the conductive inner layer and the stable outer layer, the inner layer conductive material reduces the electron transmission impedance, the outer layer ion conductor accelerates the lithium ion diffusion rate, the double coating forms a continuous and dense interface, and the high-rate charge and discharge performance and stability of the material are improved. The present application can coat lanthanide oxides or lanthanide fluorides on the outer layer to isolate the direct contact between TNO and the electrolyte, inhibit the side reaction and electrolyte decomposition, and reduce the risk of abnormal growth of the SEI film. The deposition method of pulse laser deposition (PLD) forms a dense and uniform coating layer, and the interface bonding between the coating layer and the active particles is further improved through low-temperature annealing treatment. The structure greatly delays the material structure degradation and capacity decay, effectively improves the structural stability and capacity retention rate of the electrode in the long-cycle charge and discharge process, and significantly prolongs the service life of the lithium ion battery.

[0009] In the above-mentioned lanthanide element coating coated titanium niobate negative electrode material, the target material source of the conductive inner layer in the pulse laser deposition process comprises at least one of La 0.2-0.7 Sr 0.3-0.8 TiO3, LaNiO3, La-doped TiO2, LaCoO3, CeO2.

[0010] In the above-mentioned lanthanide element coating coated titanium niobate negative electrode material, the target material source of the stable outer layer in the pulse laser deposition process comprises at least one of Li7La3Zr2O 12 (LLZO), LaPO4, LaF3, LiNbO3.

[0011] The present application introduces lanthanide element doping, induces titanium niobate lattice distortion through ion radius difference, forms oxygen vacancy structure, effectively widens lithium ion diffusion channel and increases charge storage active site, helps to relieve the structural collapse of the material in the high-rate cycle process. The present application realizes the dual enhancement of specific capacity and structural stability, so that the material of the present application can still maintain good cycle stability under the conditions of high capacity and high power.

[0012] In the above-mentioned negative electrode material coated with lanthanide element coating layer on titanium niobate, the thickness of the conductive inner layer is 5-40nm, and the thickness of the stable outer layer is 10-45nm.

[0013] The application further provides a preparation method of the above-mentioned negative electrode material coated with lanthanide element coating layer on titanium niobate, which comprises the following steps:

[0014] S1, wet ball milling titanium source and niobium source, and then calcining to obtain titanium niobate particles;

[0015] S2, wet ball milling the inner layer target material source, and then pre-sintering to obtain a precursor, then pressing into a target material matrix in a mold, and then calcining to obtain an inner layer ceramic target material;

[0016] S3, wet ball milling the outer layer target material source, and then pre-sintering to obtain a precursor, then pressing into a target material matrix in a mold, and then calcining to obtain an outer layer ceramic target material;

[0017] S4, using the inner layer ceramic target material to perform pulse laser deposition on the surface of the titanium niobate to obtain a conductive inner layer, and then using the outer layer ceramic target material to perform pulse laser deposition on the surface of the conductive inner layer to obtain a stable outer layer, and finally performing annealing treatment.

[0018] Preferably, the molar ratio of the titanium source to the niobium source in step S1 is 1:2-2.5.

[0019] Preferably, the titanium source comprises one of titanium dioxide and titanium chloride.

[0020] Further preferably, the titanium source is titanium dioxide.

[0021] Preferably, the niobium source comprises one of niobium pentoxide, niobium pentachloride and ammonium niobium oxalate.

[0022] Further preferably, the niobium source is niobium pentoxide.

[0023] Preferably, the solvent in the wet ball milling process is at least one of ethanol, propanol and isopropanol.

[0024] Further preferably, the calcining in step S1 is solid-phase calcining at a temperature increasing rate of 2-5℃ / min at 800-1100℃ for 12-24h.

[0025] In the above-mentioned preparation method of the negative electrode material coated with lanthanide element coating layer on titanium niobate, the pre-sintering in step S2 is pre-sintering at a temperature increasing rate of 2-5℃ / min at 1000-1300℃ for 3-8h.

[0026] And / or the calcining in step S2 is calcining at a temperature increasing rate of 2-5℃ / min at 1350-1500℃ for 6-15h.

[0027] Preferably, the precursor in step S2 is pressed in a mold with a diameter of 25 mm at a pressure of 15-40 MPa for 2 min to form a target base with a thickness of 1-2 mm.

[0028] In the method for preparing the lanthanide-coated titanium niobate negative electrode material, the pre-sintering in step S3 is calcined at a temperature increasing rate of 2-5 ℃ / min at 800-1000 ℃ for 3-8 h.

[0029] Preferably, the precursor in step S3 is pressed in a mold with a diameter of 25 mm at a pressure of 15-40 MPa for 2 min to form a target base with a thickness of 1-2 mm.

[0030] Preferably, the precursor in step S3 is pressed in a mold with a diameter of 25 mm at a pressure of 15-40 MPa for 2 min to form a target base with a thickness of 1-2 mm.

[0031] Further preferably, the organic binder includes at least one of PVP, ethanol, ethylene glycol, isopropyl alcohol, and acetone.

[0032] The target preparation process of the application effectively guarantees the crystal phase purity, density, and composition uniformity of the material, and provides a solid foundation for subsequent deposition of high-quality thin films through the PLD technology. At the same time, the selected target formula and preparation process parameters have good adjustability, can be flexibly adjusted according to the needs of different coating materials, and have strong adaptability and potential for large-scale production.

[0033] In the method for preparing the lanthanide-coated titanium niobate negative electrode material, during the pulse laser deposition process, the O2 gas pressure is 1-10 Pa, the target distance is 3-8 cm, the substrate temperature is 200-500 ℃, the laser energy density is 1-5 J / cm 2 , the pulse frequency is 5-20 Hz, and the deposition time is 5-20 min.

[0034] The application uses the PLD technology to realize fine control of the coating thickness, composition, and density, and further optimizes the coating adhesion by heat treatment, with high repeatability and material adaptability. At the same time, the TNO precursor can be prepared by solid phase method, hydrothermal method, sol-gel method, etc., and the coating target material can be flexibly adjusted according to application requirements, and is suitable for various conductive phases and ion conductors.

[0035] Preferably, the substrate in the pulse laser deposition process includes one of high-temperature glass, a rotating tray, and a quartz sheet.

[0036] In the method for preparing the lanthanide-coated titanium niobate negative electrode material, the annealing temperature in step S4 is 300-600 ℃, and the time is 1-3 h.

[0037] The application also provides application of the above lanthanide-coated titanium niobate negative material in a lithium ion battery.

[0038] The application has the following advantages:

[0039] 1. The core structure design of the application is to construct a double-layer coating structure composed of two types of functional coatings on the surface of titanium niobate (TNO) particles: the inner layer is an electron conductive material with high electron conductivity, which is used to enhance the overall electron transport performance of the material; the outer layer is a lithium ion conductor material, which is used to enhance lithium ion diffusion, block side reactions and stabilize the electrolyte interface. The double-layer structure not only realizes the coordinated transport of electrons and ions, but also improves the interface stability through the chemical stability of the outer layer structure, effectively reducing the side reactions and capacity decay during the cycle process. Compared with the traditional single-layer coating or single-doping method, the design has better overall electrochemical performance.

[0040] 2. The application uses pulsed laser deposition (PLD) technology to sequentially deposit the inner layer conductive target material and the outer layer lithium ion conductor target material to form a double-layer dense coating on the surface of the TNO particles, which is a key process link to ensure the performance improvement of the material. The process has the advantages of high thickness control precision, high purity and excellent adhesion, etc. By adjusting the laser energy density, substrate temperature, pulse frequency and deposition time, etc., the thickness and uniformity of the inner and outer layers are controlled respectively, so that a continuous and crack-free functional coating is obtained. In addition, the application further improves the crystallinity of the coating and the interface bonding strength with the TNO particles through annealing treatment, forming a stable interface structure.

[0041] 3. The application introduces lanthanide elements (such as La 3+ , Ce 4+ ) for coating and control into the titanium niobate crystal structure, which significantly improves the lithium ion diffusion rate and specific capacity by using its large ion radius and high valence charge characteristics, effectively avoids phase change and crystal structure collapse during charging and discharging, and improves the structural stability and long cycle performance.

[0042] 4. In order to realize the PLD deposition of the double-layer functional coating, a multi-step, parameter-controllable target material preparation method is developed, which ensures the crystal phase purity, density and uniformity of the materials used, providing a basic guarantee for subsequent high-quality PLD deposition. At the same time, the selected target material formula and process parameters can be flexibly adjusted according to different coating materials, which has good adaptability and process amplification potential. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 SEM image of the TNO particles prepared in Example 1;

[0044] Figure 2A schematic diagram of the double-coated TNO structure prepared in Example 1.

[0045] Figure 3 A comparison chart of the rate performance of Examples 1-3 and Comparative Example 1. DETAILED DESCRIPTION

[0046] The following are specific embodiments of the present application, which further describe the technical solutions of the present application, but the present application is not limited to these embodiments.

[0047] In order to make the purpose, technical solutions and advantages of the present application patent clearer and more understandable, the present application patent will be further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application patent and do not limit the present application patent.

[0048] The terms "comprising", "including", "having", "containing", or any other similar words used herein are intended to cover non-exclusive inclusion. For example, a composition, step, method, article or device that includes the listed elements does not necessarily limit to those elements only, but can include other elements not explicitly listed or inherent to such composition, step, method, article or device.

[0049] The description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like used in the present application means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms is not necessarily directed to the same embodiment or example. Moreover, the technical features involved in each embodiment of the present application can be combined with each other as long as there is no conflict.

[0050] The following will be explained in combination with specific embodiments:

[0051] Example 1:

[0052] S1: Preparation of TNO precursor: TiO2 and Nb2O5 powders were weighed and mixed in a molar ratio of Nb:Ti = 2.2:1.0, then wet ball-milled with anhydrous ethanol for 8 hours, dried at 80°C, and then heated to 900°C at a rate of 3°C / min in an air atmosphere, calcined for 16 hours, and then naturally cooled to obtain pure-phase TNO powder. Figure 1 SEM image of TNO particles prepared in Example 1; from the image, it can be seen that the TNO particle size is 1-1.5 μm, mostly in long strip distribution, and the particles are uniformly distributed.

[0053] S2: Inner layer target material La 0.5 Sr 0.5Preparation of LaSrTiO3: La2O3, SrCO3 and TiO2 were weighed according to the molar ratio, mixed, ball-milled and dried, and then pre-sintered at 1150°C at a heating rate of 3°C / min for 5 hours; the target base with a thickness of 1.5 mm was pressed in a Φ25 mm mold at a pressure of 20 MPa for 2 min, and then sintered at 1400°C at a heating rate of 3°C / min for 8 hours to obtain a LaSrTiO3 inner layer ceramic target. 0.5 Sr 0.5 TiO3 inner layer ceramic target.

[0054] S3, outer layer target Li7La3Zr2O 12 Preparation: Li2CO3, La2O3 and ZrO2 were weighed according to the molar ratio, mixed, and pre-sintered at 900°C at a heating rate of 3°C / min for 5 hours; the target base with a thickness of 1.5 mm was pressed in a Φ25 mm mold at a pressure of 20 MPa for 2 min, and then sintered at a high temperature of 1200°C at a heating rate of 3°C / min to obtain an LLZO outer layer ceramic target.

[0055] S4: PLD double-layer deposition and heat treatment: using quartz as the substrate, using a KrF laser, using the inner layer ceramic target to deposit a La 0.5 Sr 0.5 TiO3 coating (20 nm), and using the outer layer ceramic target to deposit an LLZO coating (20 nm);

[0056] During the pulse laser deposition process: O2 gas pressure 8 Pa, target distance 5 cm, substrate temperature 350°C, laser energy density 2.5 J / cm 2 , pulse frequency 12 Hz, deposition time 8 min.

[0057] S5: After deposition, the composite material was annealed in an air atmosphere at 450°C for 2 hours to obtain the lanthanide element coating coated titanium niobate negative electrode material shown in FIG. Figure 2 .

[0058] Example 2:

[0059] S1: Preparation of TNO precursor: TiO2 and Nb2O5 powders were weighed and mixed according to the molar ratio Nb:Ti = 2.2:1.0, and then wet ball-milled with anhydrous ethanol for 8 hours; after drying at 80°C, the mixture was heated to 900°C at a rate of 3°C / min in an air atmosphere, calcined for 16 hours, and then naturally cooled to obtain pure-phase TNO powder.

[0060] S2: Inner layer target material LaNiO3 preparation: La2O3, NiO were weighed according to the molar ratio and mixed, ball-milled and dried, and then pre-sintered at 1000 ℃ for 5 hours at a heating rate of 3 ℃ / min; the target material substrate with a thickness of 1.5 mm was pressed in a Φ25 mm mold at a pressure of 20 MPa for 2 min, and then sintered at 1350 ℃ for 8 hours at a heating rate of 3 ℃ / min, to obtain La 0.5 Sr 0.5 TiO3 inner layer ceramic target.

[0061] S3, outer layer target material LaPO4 preparation: La2O3, NH4H2PO4 were weighed according to the molar ratio and mixed, pre-sintered at 800 ℃ for 5 hours at a heating rate of 3 ℃ / min, and then pressed into a target material substrate with a thickness of 1.5 mm in a Φ25 mm mold at a pressure of 20 MPa for 2 min, and then sintered at a high temperature of 1200 ℃ at a heating rate of 3 ℃ / min, to obtain the LLZO outer layer ceramic target.

[0062] S4: PLD double-layer deposition and heat treatment: using quartz as the substrate, using a KrF laser, first depositing a La 0.5 Sr 0.5 TiO3 coating layer (20 nm), and then depositing a LLZO coating layer (20 nm);

[0063] During the pulsed laser deposition process: O2 gas pressure 8 Pa, target distance 5 cm, substrate temperature 350 ℃, laser energy density 2.5 J / cm 2 ; pulse frequency 12 Hz, deposition time 8 min.

[0064] S5, after deposition, the composite material was annealed in an air atmosphere at 450 ℃ for 2 hours.

[0065] Example 3:

[0066] S1: TNO precursor preparation: TiO2 and Nb2O5 powders were weighed and mixed according to the molar ratio Nb:Ti = 2.2:1.0, and then wet ball-milled with anhydrous ethanol for 8 hours, dried at 80 ℃, and then calcined at 900 ℃ in an air atmosphere at a heating rate of 3 ℃ / min for 16 hours, and then naturally cooled, to obtain pure-phase TNO powder.

[0067] S2: inner layer target material preparation (CeO2): CeO2 was weighed, ball-milled and dried, and then pre-sintered at 1150 ℃ for 5 hours at a heating rate of 3 ℃ / min; the target material substrate with a thickness of 1.5 mm was pressed in a Φ25 mm mold at a pressure of 20 MPa for 2 min, and then sintered at 1100 ℃ for 8 hours at a heating rate of 3 ℃ / min, to obtain La 0.5 Sr 0.5 TiO3 inner layer ceramic target.

[0068] S3, outer layer target preparation (LaF3): LaF3 was weighed and pre-sintered at 900℃ for 5 hours with a temperature rising rate of 3℃ / min, pressed into a Φ25mm mold with a pressure of 20MPa for 2min, and then sintered at 1200℃ with a temperature rising rate of 3℃ / min to obtain a LLZO outer layer ceramic target.

[0069] S4: PLD double layer deposition and heat treatment: using quartz as the substrate, using a Nd:YAG laser, first depositing La 0.5 Sr 0.5 TiO3 coating (20nm), and then depositing the LLZO coating (20nm);

[0070] During the pulse laser deposition process: O2 gas pressure 8Pa, target distance 5cm, substrate temperature 300℃, laser energy density 2.5J / cm 2 ; pulse frequency 12Hz, deposition time 8min.

[0071] S5, after deposition, the composite material was annealed in air atmosphere at 400℃ for 2 hours.

[0072] Example 4:

[0073] The difference from Example 1 is that step S2 does not perform a pre-sintering process.

[0074] Example 5:

[0075] The difference from Example 1 is that step S3 does not perform a pre-sintering process.

[0076] Example 6:

[0077] The difference from Example 1 is that step S2 does not perform a mold static pressure process.

[0078] Example 7:

[0079] The difference from Example 1 is that step S3 does not perform a mold static pressure process.

[0080] Example 8:

[0081] The difference from Example 1 is that step S5 does not perform an annealing process.

[0082] Comparative Example 1:

[0083] The difference from Example 1 is that only the titanium niobate prepared in step 1 is not coated.

[0084] Comparative Example 2:

[0085] The difference from Example 1 is that only step S2 is performed to coat the conductive inner layer.

[0086] Comparative Example 3:

[0087] The difference from Example 1 is that only step S3 is performed to stabilize the outer coating.

[0088] Comparative Example 4:

[0089] The difference from Example 1 is that step S3 is performed to stabilize the outer coating first, and then the conductive inner coating is performed.

[0090] The negative electrode materials prepared in the examples and comparative examples, conductive agent (acetylene black), binder (PVDF) are mixed in a ratio of 80:10:10, and a slurry is prepared with N-methyl pyrrolidone (NMP) as the solvent. The slurry is coated on a copper foil (thickness 80 μm), and the electrode is vacuum dried at 80°C for 12 hours. After rolling, the electrode is cut into pieces to prepare a button cell for electrochemical testing.

[0091] The prepared electrode is punched by a puncher with a diameter of 13 mm to obtain a circular electrode. The punched circular electrode is used as the negative electrode, a polypropylene film (Celgard 2500) is used as the separator, and a lithium sheet is used as the positive electrode. The electrolyte is 1M LiPF6-ethylene carbonate (EC): dimethyl carbonate (DMC) (1:1 wt%). A button cell (CR2032) is prepared, and the electrochemical performance is evaluated after standing for 24 h.

[0092] Table 1: Negative electrode materials of lanthanide-coated titanium niobate prepared in Examples 1-8 and Comparative Examples 1-4

[0093]

[0094]

[0095] Figure 3 The figure shows the rate performance of Examples 1-3 and Comparative Example 1. As can be seen from the figure, the test is carried out in the order of 0.1C→1C→5C→10C→20C→0.1C rate. At 0.1C, the initial specific capacity of Example 1 is more than 300 mAh·g -1 , Examples 2 and 3 are slightly lower but also at a high level, and Comparative Example 1 is only about 250 mAh·g -1 ; at high rates such as 10C and 20C, the capacity loss of Example 1 is relatively small, and at 20C there is still a certain amount of capacity remaining. After returning to 0.1C, Example 1 can recover to nearly the initial value, and the recovery degree of Examples 2 and 3 is weakened in turn; the capacity of Comparative Example 1 drops sharply to 100 mAh·g -1The following. This is because the embodiment adopts a "inner layer conductive + outer layer stable" double-coating design, cooperates with lanthanide element doping, prepares a uniform and dense coating by PLD technology, improves electronic conductivity, lithium ion diffusion rate, suppresses interface side reactions, guarantees charge transmission and structural stability under high rate, so the capacity retention and recovery are good; the comparative example has no coating protection, the electronic conductivity is low, the electronic and ion transmission is blocked under high rate, the interface side reaction is severe, the capacity is greatly attenuated, highlighting the advantages of the material in the embodiment in optimizing the rate performance.

[0096] In summary, the present application constructs a double-layer coating structure composed of two types of functional coatings on the surface of titanium niobate (TNO) particles: the inner layer is an electron conductive material with high electronic conductivity, used to enhance the overall electronic transmission performance of the material; the outer layer is a lithium ion conductor material, used to enhance lithium ion diffusion, block side reactions and stabilize the electrolyte interface. This double-layer structure not only realizes the coordinated transmission of electrons and ions, but also improves the interface stability through the chemical stability of the outer layer structure, effectively reducing the side reactions and capacity attenuation during the cycle. Compared with the traditional single-layer coating or single-doping method, this design has better comprehensive electrochemical performance, which is an important technical innovation point of the present application and should be protected as a key structural feature.

[0097] The embodiments of the present application do not exhaust the technical scope of the present application, and the new technical solutions formed by the same or multiple technical features in the embodiments of the present application are also within the scope of the present application; at the same time, in all the embodiments of the present application, the parameters in the same embodiment only represent one example (i.e. a feasible scheme) of the technical solution, and there is no strict cooperation and limitation relationship between the parameters, except for the special declaration.

[0098] The technical means disclosed in the present application is not limited to the technical means disclosed in the above technical means, but also includes the technical solutions composed of any combination of the above technical features. The above is the specific embodiment of the present application, it should be pointed out that for ordinary skilled in the art, without departing from the principle of the present application, a number of improvements and refinements can be made, which are also considered as the protection scope of the present application.

[0099] The specific embodiments described herein are merely illustrative of the spirit of the present application. Those skilled in the art of the present application can make various modifications or supplements to the described specific embodiments or use similar ways to replace them, without deviating from the spirit of the present application or exceeding the scope defined by the appended claims.

Claims

1. A lanthanide-coated titanium niobate anode material, characterized by The negative electrode material comprises, from inside to outside, titanium niobate, a conductive inner layer, and a stable outer layer, wherein at least one of the conductive inner layer and the stable outer layer contains a lanthanide element, and the conductive inner layer and the stable outer layer are prepared by pulsed laser deposition, and the thickness ratio of the conductive inner layer to the stable outer layer is 1:0.5-1.

5.

2. The lanthanide-coated titanium niobate anode material of claim 1, wherein, The target source of the conductive inner layer in the pulsed laser deposition process includes at least one of La 0.2-0.7 Sr 0.3-0.8 TiO3, LaNiO3, La-doped TiO2, LaCoO3, CeO2.

3. The lanthanide-coated titanium niobate anode material of claim 1, wherein, A target source for stable outer layer in pulsed laser deposition process includes at least one of Li7La3Zr2O 12 , LaP04, LaF3, LiNb03.

4. The lanthanide-coated titanium niobate anode material of claim 1, wherein, The thickness of the conductive inner layer is 5-40 nm, and the thickness of the stable outer layer is 10-45 nm.

5. A method of preparing a lanthanide-coated titanium niobate negative electrode material as claimed in claim 1, characterized in that, The method comprises the following steps: S1. wet ball milling a titanium source and a niobium source, and then calcining to obtain titanium niobate particles; S2. wet ball milling an inner layer target material source, and then pre-sintering to obtain a precursor, then pressing into a target material base in a mold, and then calcining to obtain an inner layer ceramic target material; S3. wet ball milling an outer layer target material source, and then pre-sintering to obtain a precursor, then pressing into a target material base in a mold, and then calcining to obtain an outer layer ceramic target material; S4. using the inner layer ceramic target material to perform pulsed laser deposition on the surface of the titanium niobate to obtain a conductive inner layer, then using the outer layer ceramic target material to perform pulsed laser deposition on the surface of the conductive inner layer to obtain a stable outer layer, and finally performing annealing treatment.

6. The method for preparing a lanthanide-coated titanium niobate anode material according to claim 5, characterized in that, The pre-sintering in step S2 is performed at a temperature increasing rate of 2-5 ℃ / min at 1000-1300 ℃ for 3-8 h. The calcining in step S2 is performed at a temperature increasing rate of 2-5 ℃ / min at 1350-1500 ℃ for 6-15 h.

7. The method for preparing a lanthanide-coated titanium niobate anode material according to claim 5, characterized in that, The pre-sintering in step S3 is performed at a temperature increasing rate of 2-5 ℃ / min at 800-1000 ℃ for 3-8 h. The calcining in step S3 is performed at a temperature increasing rate of 2-5 ℃ / min at 1000-1300 ℃ for 6-15 h.

8. The method for preparing a negative electrode material of titanium niobate coated with lanthanide element coating according to claim 5, characterized in that, In the process of pulsed laser deposition: O2 pressure is 1-10 Pa, target distance is 3-8 cm, substrate temperature is 200-500℃, laser energy density is 1-5 J / cm 2 , pulse frequency is 5-20 Hz, deposition time is 5-20 min.

9. The method of claim 5, wherein the lanthanide-coated titanium niobate anode material is prepared by the steps of: preparing a mixture of titanium niobate and a lanthanide; and coating the mixture with the lanthanide. The annealing treatment in step S4 is performed at a temperature of 300-600 ℃ for 1-3 h.

10. Use of the lanthanide element coated titanium niobate negative electrode material according to claim 1 in a lithium ion battery.

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