Lithium ion battery negative electrode material, preparation method thereof and lithium ion battery

Abstract

This invention discloses a lithium-ion battery anode material, its preparation method, and a lithium-ion battery, belonging to the field of lithium-ion battery technology. The preparation method includes: adding lithium-ion conductors and multi-walled carbon nanotubes into a high-energy ball mill jar and ball milling at high speed in a protective atmosphere; then adding Me to the high-energy ball mill jar after the ball milling of S1. m Cl n The mixture was ball-milled at high speed in a protective atmosphere to obtain a black powder. Under the same protective atmosphere, an organic solvent was added to the black powder obtained in step S2, followed by centrifugation, washing, and vacuum drying to obtain an electronic conductor / ionic conductor composite material. This electronic conductor / ionic conductor composite material utilizes the heterojunction interface formed by a nanoscale transition metal element and a lithium-ion conductor for interfacial energy storage. It exhibits ultra-high rate capability and enables rapid charging and discharging, showing broad application prospects in portable electronic devices and energy storage devices.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, and in particular to a lithium-ion battery anode material, its preparation method, and a lithium-ion battery. Background Technology

[0002] With the rapid popularization of new energy vehicles and portable electronic devices, the fast-charging performance of lithium batteries has become a core bottleneck. Currently, there is an urgent need to develop lithium-ion batteries with fast charging capabilities and long cycle life. The dominant anode materials on the market are commercial graphite and silicon-carbon anodes, but they cannot provide satisfactory capacity at high charging rates. Furthermore, under high-rate charge-discharge conditions, slow interfacial kinetics and large overpotential inhomogeneities lead to uncontrolled deposition of lithium dendrites on the electrode surface, potentially causing short circuits and thermal runaway.

[0003] Compared to traditional lithium storage mechanisms in anodes, the space charge manipulation strategy, by constructing a strong electric field gradient at a heterogeneous interface, significantly accelerates lithium-ion migration kinetics while suppressing lithium dendrite deposition. This achieves high-rate fast charging while maintaining cycle stability and safety, providing a core solution for the development of high-performance fast-charging lithium batteries. Numerous studies have demonstrated that space charge storage is an effective mechanism for rapid charging and discharging; therefore, a lithium-ion battery anode material with high cycle stability and high-rate performance is urgently needed. Summary of the Invention

[0004] This invention provides a lithium-ion battery anode material, its preparation method, and a lithium-ion battery, to solve the problems of high raw material cost, complicated synthesis process, and poor cycle stability of lithium batteries in the prior art.

[0005] To address the problems in the prior art, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing an electronic conductor / ionic conductor composite material, comprising the following steps: S1. Add lithium-ion conductors and multi-walled carbon nanotubes into the jar of a high-energy ball mill and ball mill at high speed in a protective atmosphere; S2. Add Me to the high-energy ball mill jar after S1 ball milling. m Cl n The mixture was ball-milled at high speed in a protective atmosphere to obtain a black powder. S3. Under a protective atmosphere, add an organic solvent to the black powder obtained in S2, centrifuge, wash, and vacuum dry the black powder to obtain an electronic conductor / ionic conductor composite material.

[0006] Furthermore, the protective atmosphere is argon, the ball milling speed is 350 r / min, and the high-speed ball milling time is 4 h.

[0007] Furthermore, in S1, the lithium-ion conductor is any one of lithium hydride, lithium boride, lithium nitride, and lithium phosphide.

[0008] Furthermore, in S2, Me is any one of the transition metal elements Fe, Co, Ni, and Mn.

[0009] Furthermore, in step S3, the centrifugation speed is not less than 10,000 rpm, the organic solvent is tetrahydrofuran, and the washing is performed 2-3 times.

[0010] Furthermore, in step S3, the vacuum drying temperature is 60℃-80℃, and the drying time is 10h-12h.

[0011] Secondly, the present invention also provides a lithium battery anode material, comprising carbon cloth and a coating layer, wherein the coating layer is a mixture of an electronic conductor / ion conductor composite material, a conductive agent and polyvinylidene fluoride prepared by any of the preparation methods described in the first aspect.

[0012] Thirdly, the present invention also provides a method for preparing a lithium battery anode material, comprising: preparing an electronic conductor / ion conductor composite material using any of the preparation methods described in the first aspect; The electronic conductor / ionic conductor composite material, conductive agent and polyvinylidene fluoride are uniformly mixed in a glove box filled with argon atmosphere to obtain a mixed slurry. The mixed slurry was coated onto carbon cloth and dried on a heating stage inside a glove box filled with argon atmosphere to obtain a lithium-ion battery anode material.

[0013] Fourthly, the present invention also provides a lithium-ion battery, comprising the lithium-ion battery negative electrode material described in the second aspect.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The electronic conductor / ion conductor composite material is based on the spin polarized capacitor energy storage mechanism and has ultra-high rate performance, which can achieve rapid charging and discharging under the premise of ensuring a certain energy density.

[0015] (2) The electronic conductor / ion conductor composite material utilizes the heterojunction interface formed by nanoscale transition metal elements and lithium-ion conductors for interfacial energy storage, and is protected by multi-walled carbon nanotube coating materials.

[0016] (3) The synthesis cost of electronic conductor / ionic conductor composite materials is low and has high potential value. Attached Figure Description

[0017] Figure 1 The image shows a scanning electron microscope (SEM) image of the manganese / lithium boride / multi-walled carbon nanotube composite material prepared in Example 1.

[0018] Figure 2 The rate performance of the lithium-ion battery at different current densities is shown in the figure. The manganese / lithium boride / multi-walled carbon nanotube composite material prepared in Example 1 is used as the negative electrode material of the lithium-ion battery.

[0019] Figure 3 The nickel / lithium hydride / multi-walled carbon nanotube composite material prepared in Example 2 is shown in the rate performance diagram of a lithium-ion battery under different current densities when used as a negative electrode material.

[0020] Figure 4 The rate performance of the lithium-ion battery at different current densities is shown in the figure. The composite material prepared in Example 3 is used as the negative electrode material for lithium-ion batteries. Detailed Implementation

[0021] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of this application.

[0022] Example 1 In a glove box filled with argon atmosphere, 600 mg of lithium boride, 100 mg of multi-walled nanotubes and 40 g of beads were placed in a high-energy ball mill jar, and another high-energy ball mill jar was also filled with the same 600 mg of lithium boride, 100 mg of multi-walled nanotubes and 40 g of beads. The mixture was ball-milled at 350 r / min for 4 h. After ball milling, the two high-energy ball mill jars were placed back into the glove box, and 1.3g of anhydrous manganese chloride (i.e., Mn) was added to each of the two high-energy ball mill jars. The mixture was ball milled at 350r / min for 4h to obtain a black powder. The black powder was dissolved in tetrahydrofuran, centrifuged at 11,000 rpm for 5 min, the supernatant was removed, the mixture was washed three times with tetrahydrofuran, and then vacuum dried at 70 °C for 12 h to obtain a manganese / lithium boride / multi-walled carbon nanotube composite material.

[0023] SEM images of the manganese / lithium boride / multi-walled carbon nanotube composite material prepared in Example 1, from... Figure 1 As can be seen, the morphology of the prepared sample is spherical, proving the successful preparation of the manganese / lithium boride / multi-walled carbon nanotube composite material.

[0024] Figure 2The graph shows the rate performance of lithium-ion batteries using manganese / lithium boride / multi-walled carbon nanotube composite materials as the anode material at current densities of 0.5C, 1.0C, 2.0C, 3.0C, and 4.0C. Figure 2 It can be seen that lithium-ion batteries using manganese / lithium boride / multi-walled carbon nanotube composite materials as the negative electrode material exhibit excellent rate performance.

[0025] Example 2 In a glove box filled with argon atmosphere, 300 mg of lithium hydride, 100 mg of multi-walled nanotubes and 40 g of beads were placed in a high-energy ball mill jar, and another high-energy ball mill jar was also filled with the same 300 mg of lithium hydride, 100 mg of multi-walled nanotubes and 40 g of beads. The mixture was ball-milled at 350 r / min for 4 h. After ball milling, the two high-energy ball mill jars were placed back into the glove box, and 1.42g of anhydrous nickel chloride (i.e., Ni) was added to each of the two high-energy ball mill jars. The mixture was ball milled at 350r / min for 4h to obtain a black powder. The black powder was dissolved in tetrahydrofuran, centrifuged at 11,000 rpm for 5 min, the supernatant was removed, the mixture was washed three times with tetrahydrofuran, and then vacuum dried at 70 °C for 12 h to obtain a nickel / lithium hydride / multi-walled carbon nanotube composite material.

[0026] Figure 3 This image shows the rate performance of lithium-ion batteries using a nickel / lithium hydride / multi-walled carbon nanotube composite material as the anode material at current densities of 0.2C, 0.5C, 0.7C, 1.0C, 1.5C, 2.0C, 3.0C, 4.0C, 5.0C, 6.0C, 7.0C, and 8.0C. Figure 3 It can be seen that lithium-ion batteries using nickel / lithium hydride / multi-walled carbon nanotube composite materials as the negative electrode material exhibit excellent rate performance.

[0027] Example 3 In a glove box filled with argon atmosphere, 500 mg of lithium nitride or lithium phosphide, 100 mg of multi-walled nanotubes and 40 g of beads were placed in a high-energy ball mill jar, and another high-energy ball mill jar was also filled with 500 mg of lithium nitride, 100 mg of multi-walled nanotubes and 40 g of beads. The mixture was ball-milled at 350 r / min for 4 h. After ball milling, the two high-energy ball mill jars were placed back into the glove box. 1.21g of anhydrous cobalt chloride or anhydrous ferrous chloride (i.e., Co or Fe) was added to each of the two high-energy ball mill jars. The mixture was ball milled at 350r / min for 4h to obtain a black powder. The black powder was dissolved in tetrahydrofuran, centrifuged at 11,000 rpm for 5 min, the supernatant was removed, and the mixture was washed three times with tetrahydrofuran. The mixture was then vacuum dried at 70 °C for 12 h to obtain a manganese / lithium nitride / multi-walled carbon nanotube composite material or an iron / lithium phosphide multi-walled carbon nanotube composite material.

[0028] Figure 4 This chart shows the rate performance of lithium-ion batteries using composite materials as the negative electrode material at current densities of 5.0C, 6.0C, 7.0C, 8.0C, 9.0C, and 10.0C. Figure 4 It can be seen that lithium-ion batteries using composite materials as the negative electrode material exhibit excellent rate performance.

[0029] Example 4 In a glove box filled with argon atmosphere, the manganese / lithium boride / multi-walled carbon nanotube composite material obtained in Example 1, the conductive agent (Super-P carbon black), and 10wt% polyvinylidene fluoride were weighed in a mass ratio of 70:20:10 and mixed in an agate mortar and ground. After grinding evenly, N-methylpyrrolidone (NMP) was used as a solvent and stirred thoroughly into a paste. Then, the paste was evenly coated onto a circular carbon cloth with a diameter of 1cm using a coater and dried thoroughly at 70°C for 12h to evaporate the residual NMP solvent. After drying, the lithium-ion battery anode material was obtained.

[0030] Example 5 The lithium-ion anode material prepared in Example 4 was used as the anode material for the lithium-ion battery. A lithium sheet of the same size was selected as the counter electrode. Celgard 2400 was used as the separator, and the electrolyte composition was 1M LiPF6 in DMC:EC:EMC = 1:1:1 Vol%. The electrodes, separator, and electrolyte were assembled into a 2032 coin cell (20mm diameter, 3.2mm thickness) in a glove box filled with high-purity argon gas (O2 and H2O < 0.1ppm). A battery testing system was used from 0.001 to 1.0V (relative to Li). + Constant current charge-discharge measurements were performed at room temperature for all batteries (Li), and all batteries were allowed to stand for 10 hours before testing.

[0031] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method for producing an electronic conductor / ionic conductor composite material, characterized by, Includes the following steps: S1. Add lithium-ion conductors and multi-walled carbon nanotubes into the jar of a high-energy ball mill and ball mill at high speed in a protective atmosphere; S2. After S1 complete ball milling, add Me to the high-energy ball mill jar m Cl n and high-speed ball milling in a protective atmosphere to obtain black powder; S3. Under a protective atmosphere, add an organic solvent to the black powder obtained in S2, centrifuge, wash, and vacuum dry the black powder to obtain an electronic conductor / ionic conductor composite material. In S1, the lithium-ion conductor is any one of lithium hydride, lithium boride, lithium nitride, and lithium phosphide; In S2, Me is any one of the transition metal elements Fe, Co, Ni, and Mn.

2. The method for preparing an electronic conductor / ionic conductor composite material according to claim 1, characterized in that, The protective atmosphere is argon, the ball milling speed is 350 r / min, and the high-speed ball milling time is 4 h.

3. The method of claim 1, wherein the electronic conductor / ionic conductor composite material is prepared by the steps of: (a) preparing a mixture of a polymer and an ionic liquid; (b) mixing the mixture with a conductive material; and (c) drying the mixture. In step S3, the centrifugation speed is not less than 10,000 rpm, the organic solvent is tetrahydrofuran, and the washing is performed 2-3 times.

4. The method for preparing an electronic conductor / ionic conductor composite material according to claim 1, characterized in that, In step S3, the vacuum drying temperature is 60℃-80℃, and the drying time is 10h-12h.

5. A lithium-ion battery anode material, characterized in that, It includes carbon cloth and a coating layer, wherein the coating layer is a mixture of an electronic conductor / ionic conductor composite material, a conductive agent, and polyvinylidene fluoride prepared by the method according to any one of claims 1-4.

6. A method for preparing a lithium ion battery anode material, characterized in that, The method according to any one of claims 1-4 prepares an electronic conductor / ion conductor composite material by uniformly mixing the electronic conductor / ion conductor composite material, the conductive agent, and polyvinylidene fluoride in a glove box filled with argon atmosphere to obtain a mixed slurry. The mixed slurry was coated onto carbon cloth and dried on a heating stage inside a glove box filled with argon atmosphere to obtain a lithium-ion battery anode material.

7. A lithium-ion battery, characterized by Including the lithium-ion battery anode material as described in claim 5.

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