Preparation method and low-temperature application of Te-doped tungsten niobium oxide / molybdenum niobium oxide heterojunction material

Abstract

The invention discloses a preparation method and low-temperature application of a Te-doped tungsten niobium oxide / molybdenum niobium oxide heterojunction, and belongs to the technical field of secondary batteries. The preparation method specifically comprises the following steps: carrying out high-energy ball milling and alloying on WO3, Nb2O5 and Te2O5 to obtain amorphous Te-doped tungsten niobium oxide; the preparation method comprises the following steps: carrying out high-energy ball milling and alloying on MoO3, Nb2O5 and Te2O5 to obtain amorphous Te doped molybdenum niobium oxide; uniformly mixing and compacting the amorphous Te doped tungsten niobium oxide and the amorphous Te doped molybdenum niobium oxide, and performing discharge plasma sintering in an inert atmosphere to obtain the ceramic crystal Te doped tungsten niobium oxide / molybdenum niobium oxide heterojunction material. The Te-doped tungsten niobium oxide / molybdenum niobium oxide two-phase heterojunction material designed by the invention is relatively short in synthesis time, the synthesis period is shortened, the size of crystal grains is convenient to regulate and control, the crystallinity of the material is very good, the diffusion rate of lithium ions is greatly promoted by a heterojunction interface, the electron conductivity is improved by cooperating with Te doping, and the performance of the Te-doped tungsten niobium oxide / molybdenum niobium oxide two-phase heterojunction material is improved. The material can be used as a lithium ion negative electrode material with fast charging characteristic and good low-temperature performance.

Description

Technical Field

[0001] This invention belongs to the field of secondary battery technology, specifically relating to a method for preparing Te-doped tungsten niobium-oxygen / molybdenum niobium-oxygen heterojunction materials and their application in the anode of fast-charging and low-temperature lithium-ion batteries. Background Technology

[0002] To balance environmental sustainability with economic sustainability, the lithium-ion battery-powered electric vehicle market is continuously developing. Under this trend, the iterative upgrades of fast charging technology and the research and innovation of high-energy-density batteries have become core keys to promoting sustainable development in the electric vehicle sector. The improvement of rapid energy storage capacity essentially relies on the optimization and enhancement of ion diffusion rate and electronic conductivity. Niobium-based oxides, with their unique crystal structure and excellent electrochemical properties, offer a highly promising and feasible solution for the implementation of fast charging technology. This advantage stems from their inherent three-dimensional (3D) tunnel structure, which endows the material with two core electrochemical advantages: a low lithium-ion migration energy barrier and a safe and stable operating voltage window. The essence of these properties can be traced back to its typical Wadsley-Roth phase structure. The Wadsley-Roth phase of the tungsten-niobium-oxygen (W-Nb-O) system belongs to the monoclinic crystal system. Its crystal structure has n×m MO6 (M = W, Nb) octahedra connected at common angles, forming a ReO3-like rectangular bulk structure. The rectangular bulks are connected by octahedral edge-shaping and tetrahedral corner-shaping, forming a typical crystallographic shear structure. This structure of tungsten-niobium-oxygen bulk has open tunnel spaces, which not only provide sufficient sites for lithium-ion storage, but more importantly, these interconnected three-dimensional tunnels constitute the Li-ion storage network. + The efficient transport channels that diffuse rapidly significantly reduce the risk of ion channel blockage during charging and discharging at high current densities, laying the structural foundation for the material to achieve fast-charging characteristics.

[0003] However, the presence of crystal shear planes with high lithium-ion diffusion barriers limits the long-cycle performance of tungsten-niobium-oxygen materials at high current densities and low temperatures. Furthermore, the relatively large grain size (micrometer-scale) restricts their fast-charging characteristics. Additionally, the high calcination temperatures and long calcination times in conventional synthesis methods often result in significant loss of active metal elements, reducing the concentration of electrons participating in the reaction and thus significantly decreasing their capacity. Therefore, there is an urgent need to develop a method to improve the high current density and long-cycle performance and capacity of tungsten-niobium-oxygen materials at low temperatures. Summary of the Invention

[0004] Based on the above background technology, the present invention provides a method for preparing Te-doped tungsten niobium-oxygen / molybdenum niobium-oxygen two-phase heterojunction materials and their applications, aiming to reduce the lithium-ion diffusion barrier, material band gap width, grain size and volatilization of active elements in tungsten niobium-oxygen materials, and improve their electrochemical performance such as long cycle performance and capacity at high current density and low temperature.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for preparing a Te-doped tungsten-niobium-oxygen / molybdenum-niobium-oxygen heterojunction material includes the following steps:

[0007] Step 1: High-energy ball milling alloying of WO3, Nb2O5 and Te2O5 yields amorphous Te-doped tungsten niobium oxide; high-energy ball milling alloying of MoO3, Nb2O5 and Te2O5 yields amorphous Te-doped molybdenum niobium oxide.

[0008] Step 2: Mix amorphous Te-doped tungsten niobium oxide and amorphous Te-doped molybdenum niobium oxide evenly and grind them in a mortar for 10-20 min or ball mill them at low energy (150-400 rpm) for 1-5 h to obtain a heterojunction precursor. Place the heterojunction precursor into a graphite mold and compact it. Perform discharge plasma sintering in an inert atmosphere (Ar) to obtain a ceramic-like Te-doped tungsten niobium oxide / molybdenum niobium oxide heterojunction material.

[0009] Furthermore, in step one, the molar ratio of the raw materials WO3, Nb2O5 and Te2O5 used to prepare amorphous Te-doped tungsten niobium oxide is 3:7:X, where X = 0.0425~0.85, and the molar ratio of the raw materials MoO3, Nb2O5 and Te2O5 used to prepare amorphous Te-doped molybdenum niobium oxide is 3:1:Y, where Y = 0.0125~0.25.

[0010] Furthermore, in step one, both the amorphous Te-doped tungsten niobium oxide and the amorphous Te-doped molybdenum niobium oxide are prepared using high-energy ball milling. The weighed raw materials are mixed in an argon-filled glove box and placed into a ball mill jar. High-energy ball milling with seven beads of different sizes is performed for 6–12 hours using a high-speed vibrating ball mill with a oscillation frequency ≥1800 rpm. This ensures the raw materials are uniformly mixed and alloyed to form amorphous Te-doped tungsten niobium oxide or amorphous Te-doped molybdenum niobium oxide.

[0011] Furthermore, in step two, the pressure of the discharge plasma sintering is 50~100 MPa, the temperature is 700~1100℃, and the time is 1~10 min.

[0012] An application of the Te-doped tungsten niobium oxide / molybdenum niobium oxide heterojunction material prepared by the aforementioned preparation method is described, wherein the prepared Te-doped tungsten niobium oxide / molybdenum niobium oxide heterojunction material is used as a negative electrode active material in the negative electrode of fast-charging and low-temperature lithium-ion batteries.

[0013] Furthermore, to facilitate its use as an electrode material in batteries, the prepared ceramic-like Te-doped tungsten niobium-oxygen / molybdenum niobium-oxygen heterojunction material is naturally cooled and then crushed to obtain Te-doped tungsten niobium-oxygen / molybdenum niobium-oxygen two-phase heterojunction material powder for use.

[0014] Furthermore, the crushing method is grinding or low-energy ball milling, wherein the grinding time is 10-20 min; and the low-energy ball milling speed is 150-400 rpm, and the time is 1-5 h.

[0015] Furthermore, the prepared Te-doped tungsten niobium oxide / molybdenum niobium oxide heterojunction material is used as the negative electrode active material and dispersed in a solvent with a conductive agent and a binder to obtain a negative electrode slurry. The negative electrode slurry is coated on a negative electrode current collector, and after drying, rolling, and punching, a negative electrode sheet is obtained, and then the battery is assembled.

[0016] Preferably, the binder is polyvinylidene fluoride (PVDF), the conductive agent is acetylene black, and the solvent is N-methylpyrrolidone (NMP). The mass ratio of negative electrode active material: conductive agent: binder is 80%:10%:10%.

[0017] The fast-charging and low-temperature lithium-ion battery has a stable cycle rate of up to 200C and an operating temperature range of -50℃ to 25℃.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] This invention successfully prepared Te-doped tungsten-niobium-oxygen / molybdenum-niobium-oxygen two-phase heterojunction materials for the first time. The octahedral (NbO6, WO6, MoO6) distortion at the interface of the two-phase heterojunction caused lattice expansion, which widened the lithium-ion transport channels and thus reduced the Li-ion transport at the crystal shear plane. + Activation barrier and volume change of electrode material during cycling to improve Li + The diffusion rate and reversible insertion / extraction capability are beneficial for obtaining batteries that are durable in low-temperature cycling and have good fast-charging performance. Cooperative Te doping can simultaneously reduce the band gap of both tungsten-niobium-oxygen and molybdenum-niobium-oxygen phases, increase the electron concentration transported during the charging and discharging process, and obtain lithium-ion battery anode materials with high capacity.

[0020] Conventional sintering methods typically require prolonged high-temperature calcination. Elements such as W and Mo are prone to volatilization from the crucible at high temperatures, and the amount of volatilization is difficult to control. The Te-doped tungsten-niobium-oxygen / molybdenum-niobium-oxygen two-phase heterojunction material designed in this invention is synthesized by high-energy ball milling + discharge plasma sintering. The short-time rapid pressure sintering during the discharge plasma sintering process can significantly reduce the volatilization of active metal elements (W, Nb, Mo, Te), thereby improving the capacity of the Te-doped tungsten-niobium-oxygen / molybdenum-niobium-oxygen two-phase heterojunction. Therefore, it is beneficial to obtain lithium-ion batteries with higher endurance.

[0021] This invention selects WO3, Nb2O5, MoO3, and Te2O5 as raw materials for Te-doped tungsten niobium oxide / molybdenum niobium oxide two-phase heterojunction materials. The synthesis temperatures of the designed tungsten niobium oxide and molybdenum niobium oxide materials are close, allowing them to be synthesized together, which promotes the formation of the two-phase heterojunction interface and avoids the formation of mixtures that cannot achieve the effect of optimizing electrochemical performance. Moreover, the resulting heterojunction material can exist stably in air.

[0022] The Te-doped tungsten niobium-oxygen / molybdenum niobium-oxygen two-phase heterojunction material designed in this invention has a short synthesis time, shortens the synthesis cycle, has a simple process, saves energy, and the grain size is easy to control. The material has very good crystallinity. Unlike conventional calcination methods, which result in relatively coarse grains due to high temperature and long time, this method can obtain very fine heterojunction material grains, with grains reaching the nanoscale. Therefore, the heterojunction material prepared by this invention can be used as a lithium-ion anode material with fast charging characteristics. Attached Figure Description

[0023] Figure 1 The image shows the XRD pattern of the Te-doped tungsten niobium oxide / molybdenum niobium oxide two-phase heterojunction material prepared in Example 1.

[0024] Figure 2 The graph shows a comparison of the rate performance of the Te-doped tungsten-niobium-oxygen / molybdenum-niobium-oxygen two-phase heterojunction material prepared in Example 1 with that of conventional tungsten-niobium-oxygen materials.

[0025] Figure 3 The graph shows a comparison of the ultralong cycling performance of the Te-doped tungsten niobium oxide / molybdenum niobium oxide two-phase heterojunction material prepared in Example 10 with that of conventional tungsten niobium oxide materials at a rate of 200 C.

[0026] Figure 4 The image shows a comparison of the ultra-low temperature performance of the Te-doped tungsten niobium oxide / molybdenum niobium oxide two-phase heterojunction material prepared in Example 1 with that of conventional tungsten niobium oxide material at a 2 C rate of -50℃. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only some embodiments of the invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0028] Example 1:

[0029] A method for preparing a Te-doped tungsten-niobium-oxygen / molybdenum-niobium-oxygen two-phase heterojunction material includes the following steps:

[0030] Step 1: Weigh 3 g of 2%Te-W3Nb 14 O 44 The required mass of WO3, Nb2O5, and Te2O5 (molar ratio 3:7:0.17) was determined. The raw materials were placed in a ball mill jar containing seven steel balls of different sizes within an argon-filled glove box. The jar was then sealed with Ar gas and placed in a high-energy ball mill for 12 hours (1800 rpm). The high energy caused the raw materials to alloy, forming amorphous 2% Te-W3Nb. 14 O 44 .

[0031] Step 2: Weigh 3 g of 2%Te-Mo3Nb2O 14 The required mass of MoO3, Nb2O5, and Te2O5 (molar ratio 3:1:0.05) was determined. The raw materials were placed in a ball mill jar containing seven steel balls of different sizes within an argon-filled glove box. The jar was then sealed with Ar gas and placed in a high-energy ball mill for 12 hours (1800 rpm). The high energy caused the raw materials to alloy, forming an amorphous 2% Te-Mo3Nb2O3. 14 .

[0032] Step 3: Add amorphous 2% Te-W3Nb 14 O 44 and amorphous 2%Te-Mo3Nb2O 14 Mix and grind in a mortar for 20 minutes to obtain a uniform heterojunction precursor.

[0033] Step 4: Place the heterojunction precursor into a graphite mold with an inner diameter of 12.7 mm. To prevent the material from sticking to the mold, place pre-cut circular carbon paper at both ends. Sinter the material using a spark plasma sintering apparatus at a pressure of 50 MPa and a temperature of 700℃ for 4 minutes in an Ar atmosphere to obtain a dense crystalline bulk 2%Te-W3Nb. 14 O 44 / Mo3Nb2O 14After the heterojunction material cooled to room temperature, the carbon paper and graphite on the surface were removed with sandpaper, and the bulk material was ball-milled at 400 rpm for 3 hours to break it into powder, yielding 2%Te-W3Nb crystal. 14 O 44 / Mo3Nb2O 14 Two-phase heterojunction powder.

[0034] Step 5: Obtain the crystalline form 2%Te-W3Nb 14 O 44 / Mo3Nb2O 14 Two-phase heterojunction powder, used as the negative electrode active material, polyvinylidene fluoride (PVDF) binder, and acetylene black conductive agent are dispersed in N-methylpyrrolidone (NMP) solvent at a mass ratio of 8:1:1. The mixture is magnetically stirred until homogeneous (10 h), coated onto Cu foil, dried at 80 °C for 10 h, rolled and punched to obtain the negative electrode sheet, and then assembled into a coin cell.

[0035] Example 2

[0036] The Te-doped tungsten-niobium-oxygen / molybdenum-niobium-oxygen two-phase heterojunction powder prepared in this embodiment differs from that in Example 1 in that the high-energy ball milling time in steps one and two is 10 h. All other steps are the same as in Example 1; the shorter ball milling time is beneficial for energy conservation.

[0037] Example 3

[0038] The Te-doped tungsten-niobium-oxygen / molybdenum-niobium-oxygen two-phase heterojunction powder prepared in this embodiment differs from that in Example 1 in that the high-energy ball milling time in steps one and two is 8 hours. All other steps are the same as in Example 1; the shorter ball milling time is beneficial for energy conservation.

[0039] Example 4

[0040] The Te-doped tungsten-niobium-oxygen / molybdenum-niobium-oxygen two-phase heterojunction powder prepared in this embodiment differs from that in Example 1 in that the high-energy ball milling time in steps one and two is 6 hours. All other steps are the same as in Example 1; the shorter ball milling time is beneficial for energy conservation.

[0041] Example 5

[0042] The Te-doped tungsten-niobium-oxygen / molybdenum-niobium-oxygen two-phase heterojunction powder prepared in this embodiment differs from that in Example 1 in that the discharge plasma sintering temperature in step four is 800°C. All other aspects are the same as in Example 1, with the amount of heterojunction synthesized controlled by adjusting the sintering temperature.

[0043] Example 6

[0044] The Te-doped tungsten-niobium-oxygen / molybdenum-niobium-oxygen two-phase heterojunction powder prepared in this embodiment differs from that in Example 1 in that the discharge plasma sintering temperature in step four is 900℃. All other aspects are the same as in Example 1, with the amount of heterojunction synthesized controlled by adjusting the sintering temperature.

[0045] Example 7

[0046] The Te-doped tungsten-niobium-oxygen / molybdenum-niobium-oxygen two-phase heterojunction powder prepared in this embodiment differs from that in Example 1 in that the discharge plasma sintering temperature in step four is 1000℃. All other aspects are the same as in Example 1, except that the amount of heterojunction synthesized is controlled by adjusting the sintering temperature.

[0047] Example 8

[0048] The Te-doped tungsten-niobium-oxygen / molybdenum-niobium-oxygen two-phase heterojunction powder prepared in this embodiment differs from that in Example 1 in that the discharge plasma sintering temperature in step four is 1100℃. All other aspects are the same as in Example 1, with the amount of heterojunction synthesized controlled by adjusting the sintering temperature.

[0049] Example 9

[0050] The Te-doped tungsten-niobium-oxygen / molybdenum-niobium-oxygen two-phase heterojunction powder prepared in this embodiment differs from that in Example 1 in that the discharge plasma sintering time in step four is 10 min. All other steps are the same as in Example 1; the sintering time was extended to observe whether it affected the performance.

[0051] Example 10

[0052] The Te-doped tungsten-niobium-oxygen / molybdenum-niobium-oxygen two-phase heterojunction powder prepared in this embodiment differs from that in Example 1 in that the discharge plasma sintering time in step four is 3 minutes. All other steps are the same as in Example 1; shortening the sintering time is beneficial for refining the grain size of the heterojunction.

[0053] Example 11

[0054] The Te-doped tungsten-niobium-oxygen / molybdenum-niobium-oxygen two-phase heterojunction powder prepared in this embodiment differs from that in Example 1 in that the discharge plasma sintering time in step four is 2 minutes. All other steps are the same as in Example 1; shortening the sintering time is beneficial for refining the grain size.

[0055] Example 12

[0056] The Te-doped tungsten-niobium-oxygen / molybdenum-niobium-oxygen two-phase heterojunction powder prepared in this embodiment differs from that in Example 1 in that the discharge plasma sintering time in step four is 1 min. All other steps are the same as in Example 1; shortening the sintering time is beneficial for refining the grain size.

[0057] Example 13

[0058] The Te-doped tungsten-niobium-oxygen / molybdenum-niobium-oxygen two-phase heterojunction powder prepared in this embodiment differs from that in Example 1 in that the molar ratio of WO3, Nb2O5 and Te2O5 in step one is 3:7:0.85, and the molar ratio of MoO3, Nb2O5 and Te2O5 in step two is 3:1:0.25. Adjusting the ratio is beneficial to obtaining heterojunction materials with optimal performance.

[0059] Example 14

[0060] The Te-doped tungsten-niobium-oxygen / molybdenum-niobium-oxygen two-phase heterojunction powder prepared in this embodiment differs from that in Example 1 in that the molar ratio of WO3, Nb2O5 and Te2O5 in step one is 3:7:0.0425, and the molar ratio of MoO3, Nb2O5 and Te2O5 in step two is 3:1:0.0125. Adjusting the ratio is beneficial to obtaining heterojunction materials with optimal performance.

[0061] Example 15

[0062] The Te-doped tungsten niobium oxide / molybdenum niobium oxide two-phase heterojunction powder prepared in this embodiment differs from that in Example 1 in that the sintering pressure applied to the sintering material by the spark plasma sintering instrument in step four is 70 MPa. Adjusting the sintering pressure of the material can yield heterojunction materials with different densities.

[0063] Example 16

[0064] The Te-doped tungsten niobium oxide / molybdenum niobium oxide two-phase heterojunction powder prepared in this embodiment differs from that in Example 1 in that the sintering pressure applied to the sintering material by the spark plasma sintering instrument in step four is 100 MPa. Adjusting the sintering pressure of the material can yield heterojunction materials with different densities.

[0065] Comparative Example 1

[0066] A method for preparing a crystalline tungsten-niobium oxide material powder includes the following steps:

[0067] Step 1: Weigh 3 g of W3Nb 14 O 44 The required mass of WO3 and Nb2O5 (molar ratio of 3:7) was determined by placing the raw materials into a ball mill jar containing seven steel balls of different sizes in an argon-filled glove box. The jar was then sealed with Ar gas and placed in a high-energy ball mill. The same milling time and speed as in Example 1 were used. The higher energy caused the raw materials to alloy, forming amorphous W3Nb. 14 O 44 .

[0068] Step 2: The amorphous W3Nb 14 O 44The material was placed in a graphite mold with an inner diameter of 12.7 mm. To prevent the material from sticking to the mold, pre-cut circular carbon paper was placed at both ends. The material was then sintered in an Ar atmosphere at the same pressure, temperature, and time as in Example 1 using a spark plasma sintering apparatus to obtain a dense crystalline bulk W3Nb. 14 O 44 After the material cooled to room temperature, it was removed, and the carbon paper and graphite on the surface were sanded off. The blocky material was then ball-milled at 400 rpm for 3 hours to break it into powder, yielding crystalline W3Nb. 14 O 44 powder.

[0069] Step 3: Obtain the crystal form W3Nb 14 O 44 The powder, as the negative electrode active material, the binder polyvinylidene fluoride (PVDF), and the conductive agent acetylene black are dispersed in N-methylpyrrolidone (NMP) solvent at a mass ratio of 8:1:1. The mixture is magnetically stirred until homogeneous (10 h), coated onto Cu foil, dried at 80 °C for 10 h, rolled and punched to obtain the negative electrode sheet, and then assembled into a coin cell.

[0070] The slow diffusion rate of lithium ions at the shear plane of conventional tungsten-niobium-oxygen crystals results in a low concentration of excited electrons during charging and discharging, which greatly limits their fast-charging characteristics and low-temperature cycling performance.

[0071] The Te-doped tungsten-niobium-oxygen / molybdenum-niobium-oxygen two-phase heterojunction material prepared in Example 1 was characterized by phase composition, such as... Figure 1 The XRD pattern shows that the material exhibits characteristic peaks for both phases, corresponding to standard cards PDF#00-044-0466 and PDF#97-015-3479, respectively, indicating the successful synthesis of Te-doped tungsten-niobium-oxygen / molybdenum-niobium-oxygen two-phase heterojunction material with good crystallinity. The rate performance of lithium-ion batteries assembled from the Te-doped tungsten-niobium-oxygen / molybdenum-niobium-oxygen two-phase heterojunction material and the tungsten-niobium-oxygen material prepared in Comparative Example 1 were compared, and the results are as follows: Figure 2As shown, the battery using Te-doped tungsten-niobium-oxygen / molybdenum-niobium-oxygen two-phase heterojunction material as the negative electrode has a higher specific capacity at all rates. The specific capacities at 0.2 C, 1 C, 2 C, 5 C, 10 C, 20 C, 40 C, 60 C, 100 C, 150 C, and 200 C are 260.1, 230.3, 215.6, 200.0, 184.5, 165.5, 145.4, 133.5, 120.9, 110.0, and 99.5 mAh / g, respectively. The specific capacities of batteries using conventional tungsten-niobium-oxygen (TNI) anodes at 0.2 C, 1 C, 2 C, 5 C, 10 C, 20 C, 40 C, 60 C, 100 C, 150 C, and 200 C are 240.4, 203.4, 187.3, 166.3, 146.7, 126.9, 101.9, 85.1, 55.7, 25.3, and 18.5 mAh / g, respectively. This indicates that batteries prepared with Te-doped tungsten-niobium-oxygen / molybdenum-niobium-oxygen two-phase heterojunction materials have better fast-charging characteristics and higher capacity than batteries prepared with conventional tungsten-niobium-oxygen materials. After 5500 cycles at 200 C, the battery using Te-doped tungsten-niobium-oxygen / molybdenum-niobium-oxygen two-phase heterojunction materials as the anode retains a capacity of 91.89%, while the battery using conventional tungsten-niobium-oxygen anodes only retains 68.40% of its capacity. Figure 3 As shown, the battery fabricated using Te-doped tungsten-niobium-oxygen / molybdenum-niobium-oxygen two-phase heterojunction material exhibits better long-cycle performance than batteries fabricated using conventional tungsten-niobium-oxygen material. After 500 cycles at 2 C rate at ultra-low temperature (-50℃), the battery using Te-doped tungsten-niobium-oxygen / molybdenum-niobium-oxygen two-phase heterojunction material as the anode showed no capacity decay, while the battery using conventional tungsten-niobium-oxygen material as the anode reduced its capacity retention to 62.69%. Figure 4 As shown, the battery using Te-doped tungsten-niobium-oxygen / molybdenum-niobium-oxygen two-phase heterojunction material as the negative electrode exhibits better ultra-low temperature characteristics than batteries assembled with conventional tungsten-niobium-oxygen negative electrode materials, and has great application potential.

[0072] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing a Te-doped tungsten-niobium-oxygen / molybdenum-niobium-oxygen heterojunction material, characterized in that, Includes the following steps: Step 1: High-energy ball milling alloying of WO3, Nb2O5 and Te2O5 yields amorphous Te-doped tungsten niobium oxide; high-energy ball milling alloying of MoO3, Nb2O5 and Te2O5 yields amorphous Te-doped molybdenum niobium oxide. Step 2: Mix amorphous Te-doped tungsten niobium oxide and amorphous Te-doped molybdenum niobium oxide evenly and compact them. Then, perform discharge plasma sintering under an inert atmosphere to obtain a ceramic-like Te-doped tungsten niobium oxide / molybdenum niobium oxide heterojunction material.

2. The preparation method according to claim 1, characterized in that: In step one, the molar ratio of WO3, Nb2O5 and Te2O5 used to prepare amorphous Te-doped tungsten niobium oxide is 3:7:X, where X = 0.0425~0.85; the molar ratio of MoO3, Nb2O5 and Te2O5 used to prepare amorphous Te-doped molybdenum niobium oxide is 3:1:Y, where Y = 0.0125~0.

25.

3. The preparation method according to claim 1, characterized in that: In step one, both Te-doped tungsten niobium oxide and amorphous Te-doped molybdenum niobium oxide are prepared by high-energy ball milling, with a ball milling speed ≥1800 rpm and a ball milling time of 6~12 h.

4. The preparation method according to claim 1, characterized in that: In step two, the amorphous Te-doped tungsten niobium oxide and the amorphous Te-doped molybdenum niobium oxide are mixed evenly by mortar grinding or low-energy ball milling. The mortar grinding time is 10-20 minutes, and the low-energy ball milling speed is 150-400 rpm for 1-5 hours.

5. The preparation method according to claim 1, characterized in that: In step two, the pressure of the discharge plasma sintering is 50~100 MPa, the temperature is 700~1100℃, and the time is 1~10 min.

6. The application of a Te-doped tungsten-niobium oxide / molybdenum-niobium oxide heterojunction material prepared by the preparation method according to any one of claims 1 to 5, characterized in that: The prepared Te-doped tungsten niobium-oxygen / molybdenum niobium-oxygen heterojunction material is used as a negative electrode active material in the negative electrode of fast-charging and low-temperature lithium-ion batteries.

7. The application according to claim 6, characterized in that: In application, the prepared Te-doped tungsten niobium oxide / molybdenum niobium oxide heterojunction material is crushed into powder for use.

8. The application according to claim 7, characterized in that: The crushing method is grinding or low-energy ball milling, wherein the low-energy ball milling speed is 150~400 rpm and the time is 1~5h.

9. The application according to claim 6, characterized in that: The prepared Te-doped tungsten niobium oxide / molybdenum niobium oxide heterojunction material was used as the negative electrode active material and dispersed in a solvent with a conductive agent and a binder to obtain a negative electrode slurry. The negative electrode slurry was coated on a negative electrode current collector and then dried, rolled, and punched to obtain a negative electrode sheet.

10. The application according to claim 6, characterized in that: The fast-charging and low-temperature lithium-ion battery has a stable cycle rate of up to 200C and an operating temperature range of -50℃ to 25℃.

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