Lithium alloy particle and preparation method and application thereof
By using wet chemistry method under an inert atmosphere, mixing polycyclic aromatic compounds with organic solvents, and adding metal particles to prepare lithium alloy particles, solving the problems of high temperature, high cost and dangerous operation of existing lithium alloy preparation methods, achieving safe and low-cost large-scale production, and improving the performance of lithium-ion batteries.
Patent Information
- Application Number
- CN202510329957.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-19
- Publication Date
- 2025-06-20
AI Technical Summary
The existing lithium alloy preparation methods require high temperature conditions, are costly, complex in process and dangerous in operation, and are not suitable for large-scale production.
By using wet chemistry, the polycyclic aromatic compound is mixed with an organic solvent under an inert atmosphere to form a lithium aromatic solution, and then metal particles are added to the reaction to prepare lithium alloy particles.
Lithium alloy particles with high specific capacity, small particle size and harmless impurities are safely and efficiently prepared at room temperature, which is suitable for large-scale production and improves the first-circle coulomb efficiency and energy density of lithium-ion batteries.
Smart Images
Figure CN120170100A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of lithium alloys, and particularly to a lithium alloy particle, a preparation method thereof and an application thereof. Background Art
[0002] In recent years, with the rapid development of electric vehicles and wearable devices, the performance requirements for lithium-ion batteries have been continuously improved. Among them, silicon-based anode materials have been widely studied due to their extremely high specific capacity and rich resources. However, a solid electrolyte interface (SEI) is formed in the initial cycle of silicon-based anode materials, and the SEI will decompose and reconstruct due to the volume expansion of silicon particles in subsequent cycles, thus consuming a large amount of lithium, resulting in a low first-cycle Coulomb efficiency, rapid attenuation of battery capacity, and reduction of the comprehensive performance of the battery.
[0003] As a pre-lithiation additive, a lithium alloy can compensate for the lithium loss caused by the formation of SEI in a lithium-ion battery by mixing with the anode material and de-lithiating to the outside during the first charge and discharge of the battery, so as to achieve a high first-cycle Coulomb efficiency, which has extremely high practical application value.
[0004] The existing method for preparing lithium alloys is mainly the high-temperature melting method, in which raw materials of alloy elements and a lithium source in a certain proportion are uniformly mixed, and a lithium alloy is obtained by mixing and stirring at 250°C in an inert atmosphere. The high-temperature melting method requires high-temperature conditions, and at the same time, the oxygen partial pressure < 1 ppm and the water partial pressure < 1 ppm. The preparation cost is high, the process is complex, and the operation is dangerous, which is not suitable for large-scale production.
[0005] Therefore, there is an urgent need to provide a preparation method for lithium alloys that can reduce the preparation cost, improve safety and meet the requirements of large-scale production. Summary of the Invention
[0006] The purpose of the present invention is to provide a lithium alloy particle, a preparation method thereof and an application thereof in view of the deficiencies of the prior art.
[0007] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:
[0008] The present invention provides a preparation method for lithium alloy particles, comprising the following steps:
[0009] 1) Under an inert atmosphere, a polycyclic aromatic compound is mixed with an organic solvent to obtain a precursor solution;
[0010] 2) Metallic lithium is added to the precursor solution to obtain a lithium arene solution;
[0011] 3) Metallic particles are added to the lithium arene solution for reaction to obtain lithium alloy particles.
[0012] Preferably, the polycyclic aromatic compound in step 1) is one or more of naphthalene, biphenyl, 4-methylbiphenyl, 2-methylbiphenyl, 4,4'-dimethylbiphenyl, and 2-fluorobiphenyl;
[0013] The organic solvent is one or more of ethylene glycol dimethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, and tetrahydropyran.
[0014] Preferably, the concentration of the polycyclic aromatic compound in the precursor solution in step 1) is 0.1 - 5 mol / L.
[0015] Preferably, the metallic lithium in step 2) is one or more of lithium flakes, lithium powder, lithium strips, and lithium foils, and the molar ratio of the metallic lithium to the polycyclic aromatic compound in step 1) is 1 - 8:1.
[0016] Preferably, the metal particles in step 3) are tin particles, germanium particles, or aluminum particles, the diameter of the metal particles is 1 - 50 μm, and the molar ratio of the metal particles to the metallic lithium in step 2) is 1:1 - 10.
[0017] Preferably, during the reaction in step 3), stirring is carried out, the stirring speed is 200 - 800 r / min, the reaction temperature is 25 - 60 °C, and the reaction time is 6 - 48 h.
[0018] Preferably, after the reaction in step 3), a lithium alloy suspension is obtained, and the lithium alloy suspension is centrifuged, washed, and dried in sequence to obtain lithium alloy particles.
[0019] Preferably, the centrifugation speed is 8000 - 10000 r / min, and the centrifugation time is 5 - 10 min;
[0020] The reagent used for washing is the same as the organic solvent in step 1);
[0021] The drying is carried out in an inert atmosphere, the drying temperature is 50 - 80 °C, and the drying time is 8 - 24 h.
[0022] The present invention also provides the lithium alloy particles prepared by the preparation method described above.
[0023] The present invention also provides the application of the lithium alloy particles in the negative electrode material of a lithium ion battery.
[0024] Advantages of the present invention:
[0025] The present invention adopts a wet chemical method at room temperature, with the help of a lithium arene solution having an extremely low redox potential, to embed lithium into low-cost micron tin particles, germanium particles, or aluminum particles in one step to obtain lithium alloy particles Li x Sn, Li xGe or Li x Al, with a high - safety and low - cost preparation method; the prepared lithium alloy particles have a high specific capacity (>1000 mAh / g), small particle size and do not contain harmful impurities. When added as a lithium supplement agent to the silicon - based anode material, it can effectively improve the first - cycle Coulomb efficiency and energy density of the battery, and the vacancies formed by the lithium - supplement agent after lithium deintercalation can also play a role in alleviating the volume expansion of silicon particles during cycling. Brief Description of the Drawings
[0026] Figure 1 Scanning electron microscope images of tin particles and lithium alloy particles in Example 1, where (a) is the scanning electron microscope image of tin particles and (b) is the scanning electron microscope image of lithium alloy particles;
[0027] Figure 2 X - ray diffraction pattern of the lithium alloy particles in Example 1;
[0028] Figure 3 X - ray diffraction pattern of the lithium alloy particles in Example 2;
[0029] Figure 4 First - cycle charge - discharge curve of the lithium - ion battery in Application Example 1;
[0030] Figure 5 First - cycle charge - discharge curve of the lithium - ion battery in Application Comparative Example 1. Detailed Description of the Invention
[0031] The present invention provides a preparation method of lithium alloy particles, which comprises the following steps:
[0032] 1) Under an inert atmosphere, a polycyclic aromatic compound is mixed with an organic solvent to obtain a precursor solution;
[0033] 2) Metallic lithium is added to the precursor solution to obtain a lithium - arene solution;
[0034] 3) Metallic particles are added to the lithium - arene solution for reaction to obtain lithium alloy particles.
[0035] In the present invention, the inert atmosphere in step 1) is preferably argon, the water content in the inert atmosphere is preferably <0.1 ppm, more preferably <0.05 ppm; the oxygen content in the inert atmosphere is preferably <0.1 ppm, more preferably <0.05 ppm.
[0036] In the present invention, the polycyclic aromatic compound in step 1) is preferably one or more of naphthalene, biphenyl, 4 - methylbiphenyl, 2 - methylbiphenyl, 4,4'-dimethylbiphenyl and 2 - fluorobiphenyl;
[0037] The organic solvent is preferably one or more of ethylene glycol dimethyl ether, tetrahydrofuran, 2 - methyltetrahydrofuran and tetrahydropyran.
[0038] In the present invention, the concentration of the polycyclic aromatic compound in the precursor solution in step 1) is preferably 0.1 - 5 mol / L, more preferably 1 - 4 mol / L, and still more preferably 2 - 3 mol / L.
[0039] In the present invention, the metallic lithium in step 2) is preferably one or more of lithium flakes, lithium powder, lithium strips and lithium foils, and the molar ratio of the metallic lithium to the polycyclic aromatic compound in step 1) is preferably 1 - 8:1, more preferably 3 - 7:1, and still more preferably 5 - 6:1.
[0040] In the present invention, after the addition in step 2) is completed, it is preferably stirred to obtain a lithium aromatic hydrocarbon solution. The rotation speed of the stirring is preferably 200 - 800 r / min, more preferably 400 - 600 r / min; the stirring time is preferably 1 - 4 h, more preferably 2 - 3 h.
[0041] In the present invention, the metal particles in step 3) are preferably tin particles, germanium particles or aluminum particles. The diameter of the metal particles is preferably 1 - 50 μm, more preferably 3 - 30 μm, and still more preferably 10 - 20 μm; the molar ratio of the metal particles to the metallic lithium in step 2) is preferably 1:1 - 10, more preferably 1:3 - 7.5, and still more preferably 1:4.5 - 5.
[0042] In the present invention, during the reaction in step 3), it is preferably stirred. The rotation speed of the stirring is preferably 200 - 600 r / min, more preferably 300 - 500 r / min, and still more preferably 400 r / min; the reaction temperature is preferably 25 - 60 °C, more preferably 30 - 50 °C, and still more preferably 40 °C; the reaction time is preferably 6 - 48 h, more preferably 8 - 16 h, and still more preferably 12 h.
[0043] In the present invention, after the reaction in step 3) is completed, a lithium alloy suspension is obtained. It is preferably centrifuged, washed and dried in sequence to obtain lithium alloy particles.
[0044] In the present invention, the rotation speed of the centrifugation is preferably 8000 - 10000 r / min, more preferably 8500 - 9500 r / min, and still more preferably 9000 r / min; the centrifugation time is preferably 5 - 10 min, more preferably 6 - 9 min, and still more preferably 7 - 8 min;
[0045] The reagent used for the washing is preferably the same as the organic solvent in step 1);
[0046] The drying is preferably carried out in an inert atmosphere. The drying temperature is preferably 50-80°C, more preferably 60-70°C, and even more preferably 65°C; the drying time is preferably 8-24 h, more preferably 10-20 h, and even more preferably 12-16 h.
[0047] The present invention also provides lithium alloy particles prepared by the preparation method described above.
[0048] The present invention also provides the application of the lithium alloy particles in the negative electrode material of a lithium ion battery.
[0049] In the present invention, the lithium alloy particles are preferably applied as a lithium supplement agent to the negative electrode material of a lithium ion battery.
[0050] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the protection scope of the present invention.
[0051] Example 1
[0052] In an argon atmosphere (the water content in the argon atmosphere is 0.05 ppm and the oxygen content is 0.05 ppm), 4.5 mmol of 4,4'-dimethylbiphenyl and 5 mL of 2-methyltetrahydrofuran were mixed and stirred at a speed of 400 r / min for 10 min to obtain a precursor solution. 22.5 mmol of lithium flakes were added to the precursor solution, and after the addition, the mixture was stirred at a speed of 400 r / min for 3 h to obtain a dark green lithium arene solution. 4.5 mmol of tin particles were added to the lithium arene solution, and the mixture was stirred and reacted at a speed of 400 r / min at 25°C for 12 h to obtain a lithium alloy suspension. The lithium alloy suspension was centrifuged at a speed of 9000 r / min for 8 min to obtain solid particles. The solid particles were added to 5 mL of 2-methyltetrahydrofuran for washing, and then centrifuged at a speed of 9000 r / min for 8 min. The steps of washing and centrifuging were repeated 2 times, and the centrifuged product was placed in an argon atmosphere (the water content in the argon atmosphere is 0.05 ppm and the oxygen content is 0.05 ppm) and dried at 60°C for 12 h to obtain lithium alloy particles.
[0053] The lithium alloy particles prepared in this example are lithium-tin alloys.
[0054] Figure 1 are the scanning electron microscope images of the tin particles and the lithium alloy particles in Example 1. Among them, (a) is the scanning electron microscope image of the tin particles, and (b) is the scanning electron microscope image of the lithium alloy particles. From Figure 1 (a) of can be seen that the particle size of the tin particles is in the range of 3-10 μm; from (b), it can be seen that the tin particles are broken due to volume expansion during the reaction.
[0055] Figure 2X-ray diffraction pattern of the lithium alloy particles of Example 1. It can be seen from Figure 2 that the diffraction peak of tin can no longer be detected in the lithium alloy particles, indicating that tin has been completely converted into lithium-tin alloy.
[0056] Example 2
[0057] Replace 4.5 mmol of tin particles in Example 1 with 5 mmol of germanium particles, and the particle size of the germanium particles is 10 - 20 μm.
[0058] The lithium alloy particles prepared in this example are lithium-germanium alloy.
[0059] Figure 3 X-ray diffraction pattern of the lithium alloy particles of Example 2. It can be seen from Figure 3 that the diffraction peak of germanium can no longer be detected in the lithium alloy particles, indicating that germanium has been completely converted into lithium-germanium alloy.
[0060] Example 3
[0061] In an argon atmosphere (the water content in the argon atmosphere is 0.05 ppm and the oxygen content is 0.05 ppm), mix 25 mmol of 2-methylbiphenyl and 5 mL of tetrahydrofuran, stir at a speed of 400 r / min for 10 min to obtain a precursor solution. Add 75 mmol of lithium flakes to the precursor solution, and stir at a speed of 400 r / min for 3 h after the addition to obtain a dark blue lithium arene solution. Add 10 mmol of aluminum particles (the particle size of the aluminum particles is 20 - 30 μm) to the lithium arene solution, stir and react at 40 °C at a speed of 400 r / min for 24 h to obtain a lithium alloy suspension. Centrifuge the lithium alloy suspension at a speed of 8000 r / min for 10 min to obtain solid particles. Add the solid particles to 5 mL of tetrahydrofuran for washing, and then centrifuge at a speed of 8000 r / min for 10 min. Repeat the steps of washing and centrifuging 2 times, and place the centrifuged product in an argon atmosphere (the water content in the argon atmosphere is 0.05 ppm and the oxygen content is 0.05 ppm), and dry at 50 °C for 16 h to obtain lithium alloy particles.
[0062] The lithium alloy particles prepared in this example are lithium-aluminum alloy.
[0063] Example 4
[0064] In an argon atmosphere (with a water content of 0.05 ppm and an oxygen content of 0.05 ppm in the argon atmosphere), 15 mmol of naphthalene and 5 mL of ethylene glycol dimethyl ether were mixed and stirred at a speed of 400 r / min for 10 min to obtain a precursor solution. 120 mmol of lithium flakes were added to the precursor solution, and after the addition, it was stirred at a speed of 400 r / min for 3 h to obtain a dark blue lithium arene solution. 40 mmol of tin particles (with a particle size of 1 - 10 μm) were added to the lithium arene solution, and the reaction was stirred at 30 °C and a speed of 400 r / min for 36 h to obtain a lithium alloy suspension. The lithium alloy suspension was centrifuged at a speed of 10000 r / min for 5 min to obtain solid particles. The solid particles were added to 5 mL of ethylene glycol dimethyl ether for washing, and then centrifuged at a speed of 10000 r / min for 5 min. The steps of washing and centrifuging were repeated 2 times, and the centrifuged product was placed in an argon atmosphere (with a water content of 0.05 ppm and an oxygen content of 0.05 ppm in the argon atmosphere) and dried at 70 °C for 10 h to obtain lithium alloy particles.
[0065] The lithium alloy particles prepared in this example are lithium - tin alloys.
[0066] Application Example 1
[0067] The lithium alloy particles of Example 1 were added to KELUDE silicon - carbon negative electrode 1800 (porous carbon - deposited silicon), where the mass ratio of the lithium alloy particles to the silicon - carbon negative electrode was 3:1. Using a lithium sheet as the counter electrode and electrolyte LB - 015, a lithium - ion battery was assembled with a working voltage of 0.01 - 1.5 V.
[0068] Application Comparative Example 1
[0069] Using a lithium sheet as the counter electrode, it was assembled with KELUDE silicon - carbon negative electrode 1800 (porous carbon - deposited silicon) and electrolyte LB - 015 to form a lithium - ion battery with a working voltage of 0.01 - 1.5 V.
[0070] Figure 4 is the first - cycle charge - discharge curve of the lithium - ion battery in Application Example 1. Figure 5 is the first - cycle charge - discharge curve of the lithium - ion battery in Application Comparative Example 1. From Figure 4 , 5 it can be seen that adding lithium alloy particles as a lithium supplement agent to the silicon - based negative electrode material can increase the first - cycle Coulombic efficiency of the silicon - based negative electrode material from 75.3% to 84.6%, effectively compensating for the irreversible capacity loss of the silicon - based negative electrode material in the first cycle.
[0071] The above - mentioned are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.
Claims
1. A method for preparing lithium alloy particles, characterized in that: The following steps are included: 1) Mixing a polycyclic aromatic compound with an organic solvent under an inert atmosphere to obtain a precursor solution; 2) adding metallic lithium to the precursor solution to obtain a lithium aromatic solution; 3) Adding metal particles into a lithium aromatic solution to react and obtain lithium alloy particles.
2. The preparation method according to claim 1, characterized in that: Step 1) the polycyclic aromatic compound is one or more of naphthalene, biphenyl, 4-methylbiphenyl, 2-methylbiphenyl, 4,4'-dimethylbiphenyl and 2-fluorobiphenyl; The organic solvent is one or more of ethylene glycol dimethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran and tetrahydropyran.
3. The preparation method according to claim 1 or 2, characterized in that: Step 1) The concentration of the polycyclic aromatic compounds in the precursor solution is 0.1 to 5 mol / L.
4. The preparation method according to claim 3, characterized in that: The metallic lithium in step 2) is one or more of lithium sheets, lithium powder, lithium strips and lithium foils, and the molar ratio of the metallic lithium to the polycyclic aromatic compound in step 1) is 1 to 8:
1.
5. The preparation method according to claim 4, characterized in that: The metal particles in step 3) are tin particles, germanium particles or aluminum particles, the diameter of the metal particles is 1 to 50 μm, and the molar ratio of the metal particles to the metal lithium in step 2) is 1:1 to 10.
6. The preparation method according to claim 4 or 5, characterized in that: Step 3) Stirring is performed during the reaction, the stirring speed is 200-800 r / min, the reaction temperature is 25-60° C., and the reaction time is 6-48 h.
7. The preparation method according to claim 6, characterized in that: Step 3) After the reaction is completed, a lithium alloy suspension is obtained, and the lithium alloy suspension is centrifuged, washed and dried in sequence to obtain lithium alloy particles.
8. The preparation method according to claim 7, characterized in that: The centrifugal speed is 8000-10000 r / min, and the centrifugal time is 5-10 min; The reagent used for the washing is the same as the organic solvent in step 1); The drying is carried out in an inert atmosphere, the drying temperature is 50 to 80° C., and the drying time is 8 to 24 hours.
9. Lithium alloy particles prepared by the preparation method according to any one of claims 1 to 8.
10. Use of the lithium alloy particles according to claim 9 in negative electrode materials for lithium ion batteries.