Preparation method of fast ion complex coated graphite composite material
By coating fibrous lithium salt compounds onto the surface of graphite and then performing electrospinning and gas atomization, a fast-ion composite graphite-coated composite material was prepared, which solved the problems of slow lithium-ion diffusion and poor kinetic performance in lithium-ion batteries, and achieved efficient fast charging and good cycle performance of the material.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHENZHEN GOLD MEDAL NEW ENERGY TECH CO LTD
- Filing Date
- 2022-09-30
- Publication Date
- 2026-06-19
AI Technical Summary
Existing graphite anode materials exhibit slow lithium-ion diffusion in lithium-ion batteries, high SEI film impedance, poor kinetic performance, and are prone to lithium dendrite deposition, posing safety hazards. Furthermore, the preparation methods are inconsistent, resulting in significant polarization and large cycle expansion.
A fibrous lithium salt-containing compound is coated on the surface of graphite, and the metal salt is deposited by electrospinning. Then, it is co-doped with sulfides by gas atomization to form a fast ion complex-coated graphite composite material.
It improves the lithium-ion diffusion rate, reduces material expansion, enhances electronic conductivity and kinetic properties, and improves the rate performance and cycle stability of the material.
Smart Images
Figure CN115566165B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium-ion battery material preparation, specifically relating to a method for preparing a fast-ion composite material coated with graphite. Background Technology
[0002] High-energy-density fast-charging lithium-ion batteries are attracting increasing attention due to their high energy density and fast-charging performance, and the anode material is a key factor in this development. As a commercially available graphite anode material, Li... + When embedding graphite materials, desolvation is the first step, a process that consumes energy and hinders the formation of Li. + Lithium ions diffuse into the graphite interior; and at low temperatures, the SEI film impedance is high, leading to deterioration of the kinetic characteristics of the graphite anode. Especially during charging, the electrochemical polarization of the anode is significantly intensified, easily causing the precipitation of metallic lithium and the formation of lithium dendrites, posing a safety hazard. However, coating the material surface with soft carbon, hard carbon, fast ion conductors, and their oxides can improve the lithium ion diffusion rate and rate performance. Current preparation methods mainly employ solid-phase or liquid-phase methods, which suffer from poor consistency, contact deviations between materials, significant polarization, and large cycling expansion. Summary of the Invention
[0003] The technical problem to be solved by the present invention is to provide a method for preparing a fast-ion composite coated graphite composite material, which improves the fast-charging performance of graphite material by coating the graphite surface with fibrous lithium salt-containing compounds.
[0004] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows:
[0005] A method for preparing a fast ion composite coated graphite composite material includes the following steps:
[0006] S1: Dissolve lithium salt compound, mercapto coupling agent and polymer in organic solvent to obtain spinning precursor solution;
[0007] S2: Using electrospinning technology, the spinning precursor solution is deposited on the surface of the graphite material to obtain metal salt coated graphite material;
[0008] S3: Using the metal salt-coated graphite material as the matrix and sulfide as the atomizing material, a sulfur-metal co-doped graphite composite material is obtained by gas atomization.
[0009] S4: After carbonization, the sulfur-metal co-doped graphite composite material is obtained as the fast ion composite coated graphite composite material.
[0010] Further, the mass-to-volume ratio of the lithium metal salt compound, thiol coupling agent, polymer, and organic solvent in step S1 is 1~10:1~10:100:500~1000.
[0011] Furthermore, in step S1, the lithium salt compound is any one or more of lithium sulfide, lithium fluoride, lithium chloride, lithium bromide, lithium iodide, and lithium sulfate.
[0012] Further, the polymer in step S1 is any one or more of polyvinylpyrrolidone, polymethyl methacrylate, and polyacrylonitrile with a mass concentration of 10-30%.
[0013] Furthermore, the graphite material in step S2 is graphite paper.
[0014] Furthermore, the graphite material in step S2 has a thickness of 0.1–1 mm, a porosity of 30–70%, and a purity of ≥99%.
[0015] Furthermore, the electrospinning in step S2 is performed according to the following parameters: the spinning distance is 10~25cm, the voltage is 18~22KV, and the flow rate is 10~100mL / min.
[0016] Further, the gas atomization method in step S3 includes transferring the sulfide into a vacuum chamber, first evacuating to 1~5 Pa, then introducing argon gas to 1.0~3.5 MPa, and heating to 400~1000℃, with an atomization time of 20~90 min.
[0017] Furthermore, in step S3, the sulfide is Li 10 GeP2S 12 , Li6PS5Cl, Li6PS5Br, Li6PS5I, Li6PS5ClBr, Li 10 SnP2S 12 , Li7GePS8, Li2S-SiS2, 80Li2S-20P2S5, Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 Any one or more of the following.
[0018] Furthermore, the carbonization conditions described in step S4 are: heating to 700~1100℃ and carbonizing for 1~6 hours under inert gas protection.
[0019] The beneficial effects of this invention are:
[0020] 1. An electrospinning solution composed of lithium metal salt compounds, mercapto coupling agents, and polymers is used. Relying on the high conductivity of lithium ions in lithium metal salts and the coupling effect of mercapto coupling agents, the lithium metal salt compounds form a network structure. The pores are filled with amorphous carbon formed after the carbonization of polymers, which reduces expansion, improves electronic conductivity and processing performance, and can be uniformly and densely deposited on the surface of graphite paper, thereby improving the dynamic properties of graphite paper.
[0021] 2. At the same time, compared with other coupling agents (such as silane coupling agents), mercapto coupling agents improve the structural stability of materials, specific capacity and kinetic properties by relying on the sulfur in their mercapto groups.
[0022] 3. The gas atomization method is used to allow sulfides to be uniformly deposited on the surface of metal salt-coated graphite materials. The high specific capacity of sulfur in the sulfides and the lithium ions they contain enhance the lithium ion insertion / extraction rate of the materials and improve the rate performance. Attached Figure Description
[0023] Figure 1 The image shows a SEM image of the fast ion composite coated graphite composite material prepared in Example 1. Detailed Implementation
[0024] To make the technical problems, solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0025] The preparation method of the fast ion composite coated graphite composite material of the present invention includes the following steps:
[0026] S1: A spinning precursor solution is obtained by dissolving a lithium metal salt compound, a thiol coupling agent, and a polymer in an organic solvent. The mass-to-volume ratio of the lithium metal salt compound, the thiol coupling agent, the polymer, and the organic solvent is 1~10:1~10:100:500~1000. Specifically, the lithium metal salt compound is any one or more of lithium sulfide, lithium fluoride, lithium chloride, lithium bromide, lithium iodide, and lithium sulfate. The polymer is any one or more of polyvinylpyrrolidone, polymethyl methacrylate, and polyacrylonitrile at a mass concentration of 10~30%.
[0027] S2: Subsequently, electrospinning technology is used with graphite paper as the receiving plate. Electrospinning is performed according to the following parameters: spinning gap of 10-25 cm, voltage of 18-22 kV, and flow rate of 10-100 mL / min. This allows the spinning precursor solution obtained in step S1 to be deposited on the surface of the graphite paper, resulting in metal salt-coated graphite material. The graphite paper has a thickness of 0.1-1 mm, a porosity of 30-70%, and a purity ≥99%.
[0028] S3: Subsequently, using a gas atomization method, the metal salt-coated graphite material obtained in step S2 is used as the matrix, and the sulfide is used as the atomizing material for atomization. The metal salt-coated graphite material and sulfide obtained in step S2 are transferred to a vacuum chamber. First, a vacuum is drawn to 1-5 Pa, then argon gas is introduced to 1.0-3.5 MPa, and the temperature is heated to 400-1000℃. The atomization time is 20-90 min to obtain a sulfur-metal co-doped graphite composite material. The sulfide is Li. 10 GeP2S 12 , Li6PS5Cl, Li6PS5Br, Li6PS5I, Li6PS5ClBr, Li 10 SnP2S 12 , Li7GePS8, Li2S-SiS2, 80Li2S-20P2S5, Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 Any one or more of the following.
[0029] S4: Transfer the sulfur-metal co-doped graphite composite material obtained in step S3 into a tube furnace, introduce inert gas to remove air from the tube, and heat to 700-1100℃ for carbonization for 1-6 hours to obtain the fast ion composite coated graphite composite material.
[0030] The above method will be further described in detail below through different embodiments.
[0031] Example 1
[0032] The preparation method of the fast ion composite coated graphite composite material in this embodiment includes the following steps:
[0033] S1: Weigh 5g of lithium sulfide, 5g of mercapto coupling agent and 500ml of 20% polyvinylpyrrolidone, dissolve them in 800ml of ethanol organic solvent to obtain a spinning precursor solution.
[0034] S2: Then, electrospinning technology was used, with graphite paper (parameters: thickness 0.5mm, porosity 50%, purity 99.9%) as the receiving plate, and the spinning precursor solution was deposited on the surface of the graphite paper according to the following parameters: spinning gap 20cm, voltage 20KV, flow rate 50L / min, to obtain metal salt coated graphite material.
[0035] S3: Subsequently, using metal salt-coated graphite material as the matrix, Li 10 GeP2S 12 Gas atomization is performed on the atomizing material. Metal salts are coated onto graphite materials and Li... 10 GeP2S 12 The mixture was transferred to a vacuum chamber, first evacuated to 3 Pa, then argon gas was introduced to 2 MPa, and the temperature was heated to 600 °C. The atomization time was 60 min to obtain a sulfur-metal co-doped graphite composite material.
[0036] S4: Then, the sulfur-metal co-doped graphite composite material was transferred to a tube furnace, and argon inert gas was introduced to remove the air inside the tube. The temperature was raised to 900℃ and carbonized for 3 hours to obtain a fast ion composite coated graphite composite material.
[0037] Example 2
[0038] The preparation method of the fast ion composite coated graphite composite material in this embodiment includes the following steps:
[0039] S1: Dissolve 1g of lithium fluoride, 1g of mercapto coupling agent and 100g of 10% polymethyl methacrylate in 500ml of butanediol organic solvent to obtain a spinning precursor solution.
[0040] S2: Then, electrospinning technology was used, with graphite paper (parameters: thickness 0.1mm, porosity 30%, purity 99.9%) as the receiving plate, and the spinning precursor solution was deposited on the surface of the graphite paper according to the following parameters: spinning gap 10cm, voltage 20KV, flow rate 10L / min, to obtain metal salt coated graphite material.
[0041] S3: Subsequently, metal salt-coated graphite material was used as the matrix, and Li6PS5Cl was used as the atomizing material for gas atomization. The metal salt-coated graphite material and Li6PS5Cl were transferred to a vacuum chamber. First, the vacuum was evacuated to 1 Pa, then argon gas was introduced to 1.0 MPa, and the temperature was heated to 1000℃. The atomization time was 20 min to obtain a sulfur-metal co-doped graphite composite material.
[0042] S4: Then, the sulfur-metal co-doped graphite composite material was transferred to a tube furnace, inert gas was introduced to remove the air inside the tube, and the temperature was raised to 700℃ for carbonization for 6 hours to obtain a fast ion composite coated graphite composite material.
[0043] Example 3
[0044] The preparation method of the fast ion composite coated graphite composite material in this embodiment includes the following steps:
[0045] S1: Dissolve 10g lithium chloride, 10g mercapto coupling agent and 100g 30% polyacrylonitrile in 1000ml butanediol organic solvent to obtain a spinning precursor solution.
[0046] S2: Then, electrospinning technology was used, with graphite paper (thickness of 1 mm, porosity of 70%, purity of 99.9%) as the receiving plate, and the following parameters were used: spinning spacing of 25 cm, voltage of 20 KV, and flow rate of 100 L / min to deposit the spinning precursor solution on the surface of the graphite paper to obtain metal salt coated graphite material.
[0047] S3: Subsequently, the metal salt-coated graphite material was atomized using a gas atomization method. Using the metal salt-coated graphite material as the matrix and Li6PS5Br as the atomizing material, both were transferred into a vacuum chamber. First, the vacuum was evacuated to 5 Pa, then argon gas was introduced to 3.5 MPa, and the temperature was heated to 400℃. The atomization time was 90 min, resulting in a sulfur-metal co-doped graphite composite material.
[0048] S3: Then, the sulfur-metal co-doped graphite composite material was transferred to a tube furnace, inert gas was introduced to remove the air inside the tube, and the temperature was raised to 1100℃ for carbonization for 1 hour to obtain a fast ion composite coated graphite composite material.
[0049] Comparative example:
[0050] By employing a gas atomization method, using artificial graphite as a matrix, Li 10 GeP2S 12 To atomize the material and transfer it to a vacuum chamber, the vacuum was first evacuated to 3 Pa, then argon gas was introduced to 2 MPa, and the temperature was heated to 600℃. The atomization time was 60 min to obtain lithium sulfide-coated graphite composite material. Then, it was transferred to a tube furnace, and argon gas was introduced to purge the air inside the tube. The temperature was raised to 900℃ and carbonized for 3 h to obtain lithium sulfide / amorphous carbon-doped graphite composite material.
[0051] Experimental example:
[0052] (1) SEM test
[0053] The fast ion composite material coated with graphite prepared in Example 1 was subjected to SEM testing, and the results are as follows: Figure 1 As shown. By Figure 1 It can be seen that the fast ion composite coated graphite composite material exhibits a partially lamellar structure with a particle size between 10-15 μm, and a small number of bright spots exist on the material surface.
[0054] (2) Physicochemical performance testing
[0055] The conductivity, tap density, specific surface area, and particle size of the graphite composite materials obtained in Examples 1-3 and the comparative examples were tested according to the test methods in standard GB / T-24533-2019 "Graphite Anode Materials for Lithium-ion Batteries". The test results are shown in Table 1.
[0056] Table 1. Physicochemical properties of graphite composite materials in Examples 1-3 and Comparative Examples
[0057]
[0058] As can be seen from Table 1, the electrical conductivity of the fast ion composite-coated graphite composites prepared in Examples 1-3 is significantly higher than that of the comparative example. This may be because the fast ion composite-coated graphite composites prepared in Examples 1-3 exhibit a fibrous structure on their surface, which reduces impedance and increases specific surface area. At the same time, the lithium salt in the outer layer has a high tap density, which also increases the tap density of the fast ion composite-coated graphite composite.
[0059] (3) Button cell battery test
[0060] The fast-ion composite-coated graphite composites of Examples 1-3 and the comparative lithium sulfide / amorphous carbon-doped graphite composites were assembled into coin cells according to the following methods:
[0061] The graphite composite materials prepared in Examples 1-3 and the comparative examples were used as negative electrodes and assembled into coin cells with lithium sheets, electrolytes, and separators in a glove box with argon and water contents both below 0.1 ppm. The separator was Celegard 2400; the electrolyte was a LiPF6 solution. The concentration of LiPF6 in the electrolyte was 1 mol / L, and the solvent was a mixed solution of ethylene carbonate (EC) and diethyl carbonate (DMC) at a weight ratio of 1:1.
[0062] The fabricated coin cells were labeled A-1, B-1, C-1, D-1, and E-1, respectively. The performance of the coin cells was then tested using a blue-light tester under the following conditions: 0.1C charge / discharge rate, voltage range of 0.05-2V, cycling for 3 cycles, followed by testing the discharge capacity at 1C. The 1C / 0.1C rate performance and cycle performance (25±3℃, 0.2C / 0.2C, 100 cycles) were calculated. The test results are shown in Table 2.
[0063] Table 2 Performance Test Table for Button Cells
[0064]
[0065] As can be seen from Table 2, the coin cells made by coating graphite composite materials with fast ion composites in Examples 1-3 have significantly higher discharge capacity and efficiency than the lithium sulfide / amorphous carbon-doped graphite composite materials in the comparative example.
[0066] Experimental results show that the fast-ion composite material coated with graphite of the present invention enables the battery to have good discharge capacity and efficiency. This is because coating the graphite surface with inorganic lithium salt reduces its irreversible capacity, improves the initial efficiency and specific capacity, and sulfur doping enhances the material's electronic conductivity and specific capacity, thereby improving rate performance.
[0067] (4) Performance testing of pouch batteries
[0068] The fast-ion composite graphite composites of Examples 1-3 and the comparative lithium sulfide / amorphous carbon-doped graphite composites were used as negative electrode active materials, respectively, along with the positive electrode active material ternary material (LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2), electrolyte, and separator are assembled into a 5Ah pouch battery.
[0069] The separator was Celegard 2400, and the electrolyte was a LiPF6 solution (a 1:1 volume ratio of EC and DEC, with a LiPF6 concentration of 1.3 mol / L). The fabricated pouch cells were labeled A-2, B-2, C-2, and D-2, respectively, and their cycle and rate performance were tested. The test results are detailed in Table 3.
[0070] 1) Cyclic performance: The cycle performance of the battery was tested at a charge / discharge rate of 1C / 1C, a voltage range of 2.8V-4.2V, and a temperature of 25±3℃.
[0071] 2) Rate performance: At a rate of 2C, the battery is charged to 100% SOC using constant current + constant voltage mode. Then, the constant current ratio is calculated as constant current capacity / (constant current capacity + constant voltage capacity).
[0072] Table 3 Performance Test Table for Pouch Batteries
[0073]
[0074] As shown in Table 3, the pouch batteries made from the fast-ion composite-coated graphite composite materials of Examples 1-3, using them as anode materials, exhibit significantly better cycle performance than the pouch batteries made from the comparative lithium sulfide / amorphous carbon-doped graphite composite materials. This is because the fast-ion composite-coated graphite composite materials of Examples 1-3 are coated with inorganic lithium salts, reducing lithium ion consumption during charging and discharging, and possessing high liquid retention properties, thus improving their cycle performance. Furthermore, the high electronic conductivity and good rate performance of the fast-ion composite-coated graphite composite materials of Examples 1-3 enhance the material's rate performance.
[0075] The above content is only a preferred embodiment of the present invention. For those skilled in the art, many changes can be made in the specific implementation and application scope based on the concept of the present invention. As long as these changes do not depart from the concept of the present invention, they all fall within the protection scope of the present invention.
Claims
1. A method for preparing a fast ion composite coated graphite composite material, characterized in that, Includes the following steps: S1: Dissolve lithium salt compound, mercapto coupling agent and polymer in organic solvent to obtain spinning precursor solution; S2: Using electrospinning technology, the spinning precursor solution is deposited on the surface of the graphite material to obtain metal salt coated graphite material; S3: Using the metal salt-coated graphite material as the matrix and sulfide as the atomizing material, a sulfur-metal co-doped graphite composite material is obtained by gas atomization. S4: After carbonization, the sulfur-metal co-doped graphite composite material is obtained as the fast ion composite coated graphite composite material.
2. The method for preparing the fast ion composite coated graphite composite material according to claim 1, characterized in that, The mass-to-volume ratio of the lithium metal salt compound, thiol coupling agent, polymer, and organic solvent in step S1 is 1~10:1~10:100:500~1000.
3. The method for preparing the fast ion composite coated graphite composite material according to claim 2, characterized in that, In step S1, the lithium salt compound is any one or more of lithium sulfide, lithium fluoride, lithium chloride, lithium bromide, lithium iodide, and lithium sulfate.
4. The method for preparing the fast ion composite coated graphite composite material according to claim 1, characterized in that, The polymer in step S1 is any one or more of polyvinylpyrrolidone, polymethyl methacrylate, and polyacrylonitrile with a mass concentration of 10-30%.
5. The method for preparing the fast ion composite coated graphite composite material according to claim 1, characterized in that, The graphite material mentioned in step S2 is graphite paper.
6. The method for preparing the fast ion composite coated graphite composite material according to claim 1, characterized in that, The graphite material in step S2 has a thickness of 0.1–1 mm, a porosity of 30–70%, and a purity of ≥99%.
7. The method for preparing the fast ion composite coated graphite composite material according to claim 1, characterized in that, The electrospinning in step S2 is carried out according to the following parameters: the spinning distance is 10~25cm, the voltage is 18~22KV, and the flow rate is 10~100mL / min.
8. The method for preparing the fast ion composite coated graphite composite material according to claim 1, characterized in that, The gas atomization method in step S3 includes transferring the sulfide into a vacuum chamber, first evacuating to 1~5 Pa, then introducing argon gas to 1.0~3.5 MPa, and heating to 400~1000℃, with an atomization time of 20~90 min.
9. The method for preparing the fast ion composite coated graphite composite material according to claim 1, characterized in that, The sulfide in the step S3 is Li 10 GeP2S 12 , Li6PS5CI, Li6PS5Br, Li6PS5I, Li6PS5CI Br, Li 10 SnP2S 12 , Li7GePS8, Li2S-SiS2, 80Li2S-20P2S5, Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 any one or more of the group consisting of 10. The method for preparing the fast ion composite coated graphite composite material according to claim 1, characterized in that, The carbonization conditions described in step S4 are: heating to 700~1100℃ and carbonizing for 1~6 hours under inert gas protection.