Preparation method of high-stability lithium supplement agent
The preparation of high-stability lithium supplement agents through co-precipitation method and ALD/CVD technology solves the safety hazards of hydrothermal method and incomplete iron oxidation problems, achieves uniform mixing and high conductivity of the materials, and improves the stability and electrochemical performance of the lithium supplement agents.
Patent Information
- Application Number
- CN202510500360.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-21
- Publication Date
- 2025-07-25
AI Technical Summary
In the prior art, the preparation of lithium supplement agents by hydrothermal method has a high temperature and high pressure safety hazard, and the iron source is incomplete oxidation in an alkaline environment, resulting in insufficient product stability and safety.
A high-stability lithium supplement agent was prepared by co-precipitation method. By mixing iron salts and dopant solutions in the reactor, adding complexing agents and precipitants, controlling the pH value and temperature, and subsequently spray-drying and sintering under an inert atmosphere, alumina and carbon films were coated with ALD and CVD technologies to form a uniform conductive network.
It realizes uniform mixing of raw materials under low temperature conditions, reduces Fe2+ ion content, improves the electronic conductivity and air stability of the material, reduces the residual alkali, and improves the electrochemical performance and safety of the material.
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Abstract
Description
Technical Field
[0001] The present invention relates to the field of lithium batteries, and particularly to a preparation method of a high-stability lithium supplement agent. Background Art
[0002] The lithium supplement agent is a key material used in lithium-ion batteries to supplement the loss of active lithium, aiming to improve the capacity and cycle life of the battery. By supplementing the active lithium lost during the first charge and discharge or long-term cycling of the battery (such as the lithium consumption caused by the formation of the SEI film), the first Coulomb efficiency and capacity retention rate can be improved, and the battery life can be extended.
[0003] When applying for the present invention, the applicant found through retrieval that a Chinese patent disclosed "a preparation method of a lithium supplement agent" with the application number "CN202211587905.4". This patent mainly uses the hydrothermal method to first prepare amorphous doped lithium ferrite, then adds soluble aluminum salt for aluminum coating through spraying, and then calcines at high temperature in an oxygen-deficient nitrogen atmosphere to obtain high-crystallinity lithium ferrite. It avoids the melting of residual lithium salts during calcination and the caking after cooling. At the same time, during the calcination process, a small amount of residual alkali will react with the coated aluminum, greatly reducing the presence of residual alkali, significantly improving the stability of the product, and also contributing a certain capacity. The obtained lithium ferrite has a small primary particle size, a large BET, high activity, and a high first charging capacity.
[0004] The above preparation method of a lithium supplement agent uses "lithium permanganate, ferrous gluconate", and the iron source is Fe 2+ , and lithium permanganate is the doping element manganese source. It can effectively oxidize iron to trivalent only in an acidic environment, while the reactions in the above method are all in an alkaline environment, and this oxidation process cannot be achieved, resulting in the problem of incomplete oxidation of ferrous ions. At the same time, the hydrothermal method involves high-temperature and high-pressure reactions, which have certain safety hazards and require higher requirements for the plant design to be built as Class A or Class B, with a higher investment cost. Summary of the Invention
[0005] The purpose of the present invention is to solve the disadvantages existing in the prior art, and a preparation method of a high-stability lithium supplement agent is proposed.
[0006] To achieve the above purpose, the present invention adopts the following technical scheme: A preparation method of a high-stability lithium supplement agent, characterized by including the following steps:
[0007] S1. Dissolve iron salt crystals and dopant crystals separately with pure water to prepare an iron salt solution and a dopant solution;
[0008] S2. Add the iron salt solution and the dopant solution into a reaction kettle, add a complexing agent and a precipitant for mixing reaction. During the reaction process, introduce Gas 1, adjust the temperature and pressure inside the reaction kettle. After the reaction ends, add an organic acid and a conductive agent solution, adjust the pH, and perform aging to obtain a precursor solution;
[0009] S3. Spray-dry the precursor solution in an inert atmosphere to obtain a precursor powder;
[0010] S4. Sinter the precursor powder to obtain highly conductive Li5FeO4;
[0011] S5. Put the highly conductive Li5FeO4 into an ALD device, introduce an aluminum source, control the temperature, coat 1 - 3 nm of aluminum oxide to form a dense nano-aluminum oxide film, and obtain Li5FeO4@Al;
[0012] S6. Put Li5FeO4@Al into a CVD fluidized bed, introduce Gas 2, raise the temperature, introduce an alkyne gas, and react for 1 - 4 h to prepare highly stable Li5FeO4@Al@C.
[0013] As a further description of the above technical solution:
[0014] In step S1, the iron salt crystal is one or more of ferric nitrate, ferric oxalate, and ferric chloride; in step S1, the dopant is one or more of aluminum nitrate, zirconium nitrate, zinc nitrate, aluminum oxalate, zirconium oxalate, and zinc oxalate.
[0015] As a further description of the above technical solution:
[0016] In step S2, the precipitant is one or more of lithium hydroxide, lithium nitrate, and lithium carbonate; in step S2, the complexing agent is one or more of ammonia water, ammonium carbonate, and ammonium bicarbonate. In step S2, Gas 1 is ozone; in step S2, the organic acid is one or more of citric acid, oxalic acid, and ascorbic acid; in step S2, the conductive agent solution is one or more of aqueous solvents such as Super P, CNT, and GO.
[0017] As a further description of the above technical solution:
[0018] In step S2, the reaction temperature inside the reaction kettle during the reaction process is 70 - 95 °C, the pressure is 0 - 0.5 Mpa, the continuous reaction time is 5 - 10 h. After the reaction in the reaction kettle in step S2 ends, the pH is adjusted to 8 - 9, and the aging time is 2 - 4 h.
[0019] As a further description of the above technical solution:
[0020] In step S4, the sintering time of the precursor powder in a sintering furnace is 10 - 20 h.
[0021] As a further description of the above technical solution:
[0022] In step S5, the aluminum source is one or more of trimethylaluminum, triisobutylaluminum, and triethylaluminum.
[0023] As a further description of the above technical solution:
[0024] In step S5, the temperature of the ALD device is controlled at 80 - 150 °C.
[0025] As a further description of the above technical solution:
[0026] In step S6, gas 2 is one of argon, nitrogen, and neon; in step S6, the alkyne gas is one or more of acetylene, propyne, and butyne.
[0027] As a further description of the above technical solution:
[0028] When the temperature in the CVD fluidized bed rises to 500 - 700 °C, the alkyne gas is introduced.
[0029] The present invention has the following beneficial effects:
[0030] 1. Compared with the prior art, the preparation method of this high - stability lithium supplementing agent uses the coprecipitation method to replace the general solid - phase process, which can promote the uniform mixing of iron, lithium, and doping elements in the raw materials. It helps to form metal oxides and molten lithium sources during the low - temperature sintering process. At the same time, the voids generated by the dehydration of the iron source and doping elements can adsorb the molten lithium source, which not only ensures the uniformity of the materials but also improves the reaction activity of the raw materials; and compared with the prior art that uses the hydrothermal method involving high - temperature and high - pressure reactions, there are certain safety hazards and higher requirements for the plant design, which need to be built as Class A or Class B. The preparation method of this high - stability lithium supplementing agent uses the coprecipitation method to mix the elements at the atomic level, and the plant only needs to be Class D, with lower investment costs.
[0031] 2. Compared with the prior art, the preparation method of this high - stability lithium supplementing agent effectively reduces the content of Fe 2+ ions in the material through a strongly oxidizing atmosphere, and oxidizes the doping ions into unstable high - valence ions, reducing the material heterophase and improving the material capacity.
[0032] 3. Compared with the prior art, the preparation method of this high - stability lithium supplementing agent uses the conductive agent solution to form a uniform conductive network between alumina and Li5FeO4, promoting the efficient transmission of electrons between the active substances, significantly improving the electronic conductivity of the material, and further optimizing the electrochemical performance of the material.
[0033] 4. Compared with the prior art, the preparation method of the high-stability lithium supplementing agent adopts ALD atomic deposition and CVD chemical vapor deposition technologies to coat a dense nano-aluminum oxide film and a conductive carbon film on the surface of the material. This not only reduces the residual alkali amount of the material but also significantly improves the air stability of the material. BRIEF DESCRIPTION OF THE DRAWINGS
[0034] Figure 1 SEM diagram of Li5FeO4@Al@C of the preparation method of the high-stability lithium supplementing agent proposed by the present invention;
[0035] Figure 2 XRD diagram of Li5FeO4 of the preparation method of the high-stability lithium supplementing agent proposed by the present invention;
[0036] Figure 3 EDS spectrum diagram of Li5FeO4@Al@C of the preparation method of the high-stability lithium supplementing agent proposed by the present invention;
[0037] Figure 4 SEM diagram of the lithium supplementing agent Li5FeO4 in the comparative case proposed by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0038] The preparation method of the high-stability lithium supplementing agent provided by the present invention is characterized in that it includes the following steps:
[0039] S1. Dissolve iron salt crystals and dopant crystals in pure water respectively to prepare an iron salt solution and a dopant solution, wherein the iron salt crystals are one or more of ferric nitrate, ferric oxalate, and ferric chloride, and the dopant is one or more of aluminum nitrate, zirconium nitrate, zinc nitrate, aluminum oxalate, zirconium oxalate, and zinc oxalate;
[0040] S2. Add the iron salt solution and the dopant solution into a reaction kettle, and add a complexing agent and a precipitating agent for mixing reaction. During the reaction process, gas 1 is introduced (the mixing reaction is carried out in a strong oxidation atmosphere), and the temperature and pressure in the reaction kettle are adjusted. Specifically, the reaction temperature in the reaction kettle is 70 - 95 °C, the pressure is 0 - 0.5 Mpa, and the continuous reaction time is 5 - 10 h. After the reaction, an organic acid and a conductive agent solution are added to adjust the pH and aging is carried out. Specifically, the pH is adjusted to 8 - 9, and the aging time is 2 - 4 h to obtain a precursor solution, wherein the precipitating agent is one or more of lithium hydroxide, lithium nitrate, and lithium carbonate, the complexing agent is one or more of ammonia water, ammonium carbonate, and ammonium bicarbonate, and gas 1 is ozone. Ozone is introduced for strong oxidation to oxidize the impurity Fe 2+ to Fe 3+ , oxidize the doping element to an unstable higher valence state to prevent H2 generated during the subsequent CVD process from reducing Fe 3+ to Fe 2+Or Fe, the organic acid is one or more of citric acid, oxalic acid, and ascorbic acid; the conductive agent solution is one or more of aqueous solvents such as Super P, CNT, and GO;
[0041] S3. Spray-dry the precursor solution in an inert atmosphere to obtain precursor powder;
[0042] S4. Sinter the precursor powder to obtain highly conductive Li5FeO4. Specifically, the sintering time of the precursor powder in a sintering furnace is 10 - 20 h;
[0043] S5. Place the highly conductive Li5FeO4 into an atomic deposition ALD device, introduce an aluminum source, and control the temperature. Specifically, the temperature is controlled at 80 - 150 °C, and alumina is coated with a thickness of 1 - 3 nm to form a dense nano-alumina film, obtaining Li5FeO4@Al (Li5FeO4 coated with a layer of alumina), where the aluminum source is one or more of trimethylaluminum, triisobutylaluminum, and triethylaluminum;
[0044] S6. Place Li5FeO4@Al into a chemical vapor deposition CVD fluidized bed, introduce gas 2 (under an inert atmosphere), heat up to 500 - 700 °C, introduce an alkyne gas (as a carbon source), and react for 1 - 4 h to prepare highly stable Li5FeO4@Al@C (Li5FeO4 with the first layer coated with alumina and the second layer coated with carbon). Among them, gas 2 is one of argon, nitrogen, and neon, and the alkyne gas is one or more of acetylene, propyne, and butyne; @Al is coated with an aluminum film, @C is coated with a uniform carbon layer, and the stability and conductivity of the material are improved through two-layer coating.
[0045] Example 1:
[0046] Ferric nitrate, aluminum nitrate, and lithium hydroxide are respectively dissolved in hot pure water to obtain a 2 mol / L ferric nitrate solution, a 0.2 mol / L aluminum nitrate solution, and a 6 mol / L lithium hydroxide solution. The complexing agent is 0.3 mol / L ammonia water. Add pure water, ammonia water, and lithium hydroxide as the bottom solution, with a pH of 10.75 - 10.85, an ammonia concentration of 0.2 mol / L, and a reactor temperature of 80 °C. Add the ferric nitrate solution, aluminum nitrate, and lithium hydroxide into the reactor at flow rates of 2000 ml / h, 200 ml / h, and 1700 ml / h respectively. While feeding, introduce O3 at a flow rate of 0.1 L / min. Stop when the particle size reaches 5.35 μm and close the gas flowmeter.
[0047] After the reaction ends, add the lithium hydroxide solution, control the gold-lithium ratio at 1:5.20 - 5.25, then add the oxalic acid solution, control the pH at 7.5 - 8.0, add a 2 wt% CNT solution, and age at 80 °C for 2 h to obtain the precursor solution.
[0048] The precursor is dissolved and passed through a spray dryer to obtain precursor powder. The outlet temperature of the spray dryer is controlled at 110 - 115 °C.
[0049] The precursor powder is loaded into a crucible and sintered in an atmosphere furnace. It is heated at a rate of 5 °C / min, sintered at 200 °C, 400 °C, 550 °C, and 650 °C for 1.5 h, and sintered at 775 °C for 15 h, and then cooled naturally to obtain a high-conductivity Li5FeO4 lithium supplement agent.
[0050] The high-conductivity Li5FeO4 lithium supplement agent is placed in an ALD device. Trimethylaluminum is used as the aluminum source, and it is coated at 120 °C for 0.5 nm. After cooling, this material is placed in a CVD fluidized bed. Nitrogen is passed at 30 L / min, and it is heated at a rate of 10 °C / min to 700 °C, and propyne gas is introduced, and it is kept warm for 2 h to obtain high-stability Li5FeO4@Al@C with a carbon content of 2.15%.
[0051] Example 2:
[0052] Iron nitrate, aluminum nitrate, and lithium hydroxide are respectively dissolved in hot pure water to obtain a 2 mol / L iron nitrate solution, a 0.2 mol / L aluminum nitrate solution, and a 6 mol / L lithium hydroxide solution. The complexing agent is 0.3 mol / L ammonia water. Pure water, ammonia water, and lithium hydroxide are added as the bottom solution, with a pH of 10.75 - 10.85, an ammonia concentration of 0.2 mol / L, and a temperature in the autoclave of 80 °C. The iron nitrate solution, aluminum nitrate, and lithium hydroxide are respectively added to the inside of the reaction kettle at a flow rate of 2000 ml / h, 200 ml / h, and 1700 ml / h. While feeding, O3 is introduced at a flow rate of 0.1 L / min. Stop when the particle size reaches 5.35 μm, and close the gas flowmeter.
[0053] After the reaction ends, lithium hydroxide solution is added to control the gold-lithium ratio at 1:5.20 - 5.25, then oxalic acid solution is added to control the pH at 7.5 - 8.0, and 2 wt% CNT solution is added, and it is aged at 80 °C for 2 h to obtain a precursor solution.
[0054] The precursor is dissolved and passed through a spray dryer to obtain precursor powder. The outlet temperature of the spray dryer is controlled at 110 - 115 °C.
[0055] The precursor powder is loaded into a crucible and sintered in an atmosphere furnace. It is heated at a rate of 5 °C / min, sintered at 200 °C, 400 °C, 550 °C, and 650 °C for 1.5 h, and sintered at 775 °C for 15 h, and then cooled naturally to obtain a high-conductivity Li5FeO4 lithium supplement agent.
[0056] Put the high-conductivity Li5FeO4 lithium supplement agent into the ALD equipment. Using trimethylaluminum as the aluminum source, coat it at 120°C for 1.0 nm. After cooling, put this material into the CVD fluidized bed. With nitrogen at 30 L / min, heat it up to 700°C at a heating rate of 10°C / min, introduce propyne gas, and keep it warm for 2 h to obtain highly stable Li5FeO4@Al@C with a carbon content of 2.18%.
[0057] Example 3:
[0058] Dissolve ferric nitrate, aluminum nitrate, and lithium hydroxide in hot pure water respectively to obtain a 2 mol / L ferric nitrate solution, a 0.2 mol / L aluminum nitrate solution, and a 6 mol / L lithium hydroxide solution. The complexing agent is 0.3 mol / L ammonia water. Add pure water, ammonia water, and lithium hydroxide as the bottom liquid, with pH at 10.75 - 10.85, ammonia concentration of 0.2 mol / L, and the temperature in the autoclave at 80°C. Add the ferric nitrate solution, aluminum nitrate, and lithium hydroxide into the reaction kettle at a flow rate of 2000 ml / h, 200 ml / h, and 1700 ml / h respectively. While feeding, introduce O3 at a flow rate of 0.1 L / min. Stop the machine when the particle size grows to 5.35 μm and close the gas flowmeter.
[0059] After the reaction ends, add the lithium hydroxide solution, control the gold-lithium ratio at 1:5.20 - 5.25, then add the oxalic acid solution, control the pH at 7.5 - 8.0, add a 2 wt% CNT solution, and age at 80°C for 2 h to obtain the precursor solution.
[0060] The precursor is dissolved and passed through a spray dryer to obtain the precursor powder. Control the outlet temperature of the spray dryer at 110 - 115°C.
[0061] Load the precursor powder into the sagger and put it into the atmosphere furnace for sintering. Heat it up at 5°C / min, sinter at 200°C, 400°C, 550°C, and 650°C for 1.5 h, sinter at 775°C for 15 h, and cool naturally to obtain the high-conductivity Li5FeO4 lithium supplement agent.
[0062] Put the high-conductivity Li5FeO4 lithium supplement agent into the ALD equipment. Using trimethylaluminum as the aluminum source, coat it at 120°C for 1.5 nm. After cooling, put this material into the CVD fluidized bed. With nitrogen at 30 L / min, heat it up to 700°C at a heating rate of 10°C / min, introduce propyne gas, and keep it warm for 2 h to obtain highly stable Li5FeO4@Al@C with a carbon content of 2.21%.
[0063] Example 4:
[0064] Iron nitrate, aluminum nitrate, and lithium hydroxide are separately dissolved in hot pure water to obtain a 2 mol / L iron nitrate solution, a 0.2 mol / L aluminum nitrate solution, and a 6 mol / L lithium hydroxide solution. The complexing agent is 0.3 mol / L ammonia water. Add pure water, ammonia water, and lithium hydroxide as the bottom solution, with a pH of 10.75 - 10.85, an ammonia concentration of 0.2 mol / L, and a temperature inside the autoclave of 80°C. Add the iron nitrate solution, aluminum nitrate, and lithium hydroxide into the reaction kettle at a flow rate of 2000 ml / h, 200 ml / h, and 1700 ml / h respectively. While feeding, introduce O3 at a flow rate of 0.1 L / min. Stop the machine when the particle size grows to 5.35 μm, and close the gas flowmeter.
[0065] After the reaction is completed, add the lithium hydroxide solution to control the gold-lithium ratio at 1:5.20 - 5.25. Then add the oxalic acid solution to control the pH at 7.5 - 8.0. Add a 2 wt% CNT solution and age at 80°C for 2 h to obtain the precursor solution.
[0066] The precursor is dissolved and passed through a spray dryer to obtain the precursor powder. The outlet temperature of the spray dryer is controlled at 110 - 115°C.
[0067] Load the precursor powder into a crucible and place it in an atmosphere furnace for sintering. Heat it at a rate of 5°C / min, sinter at 200°C, 400°C, 550°C, and 650°C for 1.5 h, and sinter at 775°C for 15 h. Then cool it naturally to obtain the high-conductivity Li5FeO4 lithium supplement agent.
[0068] Put the high-conductivity Li5FeO4 lithium supplement agent into an ALD device, use trimethylaluminum as the aluminum source, coat it at 120°C for 2.0 nm. After cooling, put this material into a CVD fluidized bed, with nitrogen at 30 L / min, heat it at a rate of 10°C / min to 700°C, and introduce propyne gas. Keep it warm for 2 h to obtain the highly stable Li5FeO4@Al@C with a carbon content of 2.17%.
[0069] Example 5:
[0070] Iron nitrate, aluminum nitrate, and lithium hydroxide are separately dissolved in hot pure water to obtain a 2 mol / L iron nitrate solution, a 0.2 mol / L aluminum nitrate solution, and a 6 mol / L lithium hydroxide solution. The complexing agent is 0.3 mol / L ammonia water. Add pure water, ammonia water, and lithium hydroxide as the bottom solution, with a pH of 10.75 - 10.85, an ammonia concentration of 0.2 mol / L, and a temperature inside the autoclave of 80°C. Add the iron nitrate solution, aluminum nitrate, and lithium hydroxide into the reaction kettle at a flow rate of 2000 ml / h, 200 ml / h, and 1700 ml / h respectively. While feeding, introduce O3 at a flow rate of 0.1 L / min. Stop the machine when the particle size grows to 5.35 μm, and close the gas flowmeter.
[0071] After the reaction is completed, lithium hydroxide solution is added, and the gold-lithium ratio is controlled at 1:5.20 - 5.25. Then, oxalic acid solution is added, and the pH is controlled at 7.5 - 8.0. 2wt% CNT solution is added, and the mixture is aged at 80°C for 2h to obtain a precursor solution.
[0072] The precursor is dissolved and passed through a spray dryer to obtain precursor powder. The outlet temperature of the spray dryer is controlled at 110 - 115°C.
[0073] The precursor powder is loaded into a crucible and sintered in an atmosphere furnace. It is heated at a rate of 5°C / min, sintered at 200°C, 400°C, 550°C, and 650°C for 1.5h, and sintered at 775°C for 15h, and then cooled naturally to obtain a highly conductive Li5FeO4 lithium supplement agent.
[0074] The highly conductive Li5FeO4 lithium supplement agent is placed in an ALD device. Trimethylaluminum is used as the aluminum source, and it is coated at 120°C for 2.5nm. After cooling, this material is placed in a CVD fluidized bed. Nitrogen is supplied at 30L / min, and it is heated at a rate of 10°C / min to 700°C, and propyne gas is introduced, and it is kept warm for 2h to obtain highly stable Li5FeO4@Al@C with a carbon content of 2.13%.
[0075] Comparative Example 1:
[0076] Iron oxide and lithium hydroxide are added to water according to a gold-lithium ratio of 1:5.3 - 5.4, and the solid content is controlled at 30%. It is milled in a sand mill for 4h to obtain a precursor solution.
[0077] The precursor is dissolved and passed through a spray dryer to obtain precursor powder. The outlet temperature of the spray dryer is controlled at 110 - 115°C.
[0078] The precursor powder is loaded into a crucible and sintered in an atmosphere furnace. It is heated at a rate of 5°C / min, sintered at 200°C, 400°C, and 550°C for 1.5h, and sintered at 650°C for 12h, and then cooled naturally to obtain a low-purity Li5FeO4 lithium supplement agent.
[0079] The first-fired material is crushed by a jet mill and re-loaded into a crucible for secondary sintering. It is heated at a rate of 5°C / min, sintered at 200°C, 400°C, 600, and 700°C for 1h, and sintered at 800°C for 15h, and then cooled naturally to obtain a Li5FeO4 lithium supplement agent.
[0080] Pitch is mixed with Li5FeO4, and the mixture is sintered at 300°C for 8h in an inert atmosphere to obtain Li5FeO4@C with a carbon content of 2.19%.
[0081] Table 1 shows the parameters of the lithium supplement materials in the examples and comparative examples. Among them, the moisture absorption rate is measured under the conditions of a test temperature of 25 ± 1°C and a relative humidity of 30 ± 1% for 10min.
[0082]
[0083]
[0084] Table 1
[0085] Working principle: The co-precipitation method is adopted to replace the general solid-phase process, which can promote the uniform mixing of iron, lithium and doping elements in the raw materials. It helps to form metal oxides and molten lithium sources during the low-temperature sintering process. At the same time, the voids generated by the dehydration of iron sources and doping elements can adsorb the molten lithium sources, which not only ensures the uniformity of the materials, but also improves the reaction activity of the raw materials.
[0086] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.
Claims
1. A preparation method of a high-stability lithium supplementing agent, characterized in that, It includes the following steps: S1. Dissolve iron salt crystals and dopant crystals separately in pure water to prepare an iron salt solution and a dopant solution; S2. Add the iron salt solution and the dopant solution into a reaction kettle, add a complexing agent and a precipitating agent and mix them for reaction. During the reaction process, introduce gas 1, adjust the temperature and pressure in the reaction kettle. After the reaction is completed, add an organic acid and a conductive agent solution, adjust the pH, and carry out aging to obtain a precursor solution; S3. Spray-dry the precursor solution in an inert atmosphere to obtain a precursor powder; S4. Sinter the precursor powder to obtain highly conductive Li5FeO4; S5. Put the highly conductive Li5FeO4 into an ALD device, introduce an aluminum source, control the temperature, coat with 1-3 nm of alumina to form a dense nano-alumina film, and obtain Li5FeO4@Al; S6. Put Li5FeO4@Al into a CVD fluidized bed, introduce gas 2, raise the temperature, introduce an alkyne gas, and react for 1-4 h to prepare highly stable Li5FeO4@Al@C.
2. The preparation method of a high-stability lithium supplementing agent according to claim 1, wherein: In step S1, the iron salt crystals are one or more of iron nitrate, iron oxalate, and iron chloride; in step S1, the dopant is one or more of aluminum nitrate, zirconium nitrate, zinc nitrate, aluminum oxalate, zirconium oxalate, and zinc oxalate.
3. The preparation method of a high-stability lithium supplementing agent according to claim 1, wherein: In step S2, the precipitating agent is one or more of lithium hydroxide, lithium nitrate, and lithium carbonate; in step S2, the complexing agent is one or more of ammonia water, ammonium carbonate, and ammonium bicarbonate. In step S2, gas 1 is ozone; in step S2, the organic acid is one or more of citric acid, oxalic acid, and ascorbic acid; in step S2, the conductive agent solution is one or more of water-based solvents such as Super P, CNT, and GO.
4. The preparation method of a highly stable lithium supplementing agent according to claim 1, characterized in that: In step S2, the reaction temperature in the reaction kettle during the reaction process is 70-95 °C, the pressure is 0-0.5 Mpa, the continuous reaction time is 5-10 h. After the reaction in the reaction kettle in step S2 is completed, the pH is adjusted to 8-9, and the aging time is 2-4 h.
5. The preparation method of a high-stability lithium supplement agent according to claim 1, characterized in that: In step S4, the sintering time of the precursor powder in the sintering furnace is 10-20 h.
6. The preparation method of a high-stability lithium supplement agent according to claim 1, wherein: In step S5, the aluminum source is one or more of trimethylaluminum, triisobutylaluminum, and triethylaluminum.
7. The preparation method of a high-stability lithium supplementing agent according to claim 1, wherein: In step S5, the temperature of the ALD device is controlled at 80-150 °C.
8. The preparation method of a high-stability lithium supplement agent according to claim 1, characterized in that: In step S6, gas 2 is one of argon, nitrogen, and neon; in step S6, the alkyne gas is one or more of acetylene, propyne, and butyne.
9. The preparation method of a high-stability lithium supplement agent according to claim 1, characterized in that: The temperature in the CVD fluidized bed is raised to 500-700 °C and then the alkyne gas is introduced.
Citation Information
Patent Citations
A preparation method of lithium supplement
CN116230842B