Preparation method of lithium or sodium supplementing material, product and application thereof

Abstract

This invention proposes a method for preparing lithium- or sodium-supplementing materials, the resulting products, and their applications, belonging to the field of battery additive technology. The method for preparing the lithium- or sodium-supplementing materials includes the following steps: 1) mixing N-source and M-source powders to obtain precursor powder; 2) subjecting the precursor powder to a first calcination and a second calcination in a vacuum environment to obtain the lithium- or sodium-supplementing materials; the first calcination temperature is 700–1000℃ for 1–5 hours, and the second calcination temperature is 500–700℃ for 3–5 hours, with the first calcination temperature being higher than the second calcination temperature. The product prepared by the method provided by this invention has a small particle size and low residual alkali; through vacuum sintering, the second sintering temperature and sintering time can be reduced, effectively reducing energy consumption and costs.

Description

Technical Field

[0001] This invention belongs to the field of battery additive preparation technology, and particularly relates to a method for preparing lithium or sodium supplement materials, the resulting products, and their applications. Background Technology

[0002] During formation and the first charge / discharge cycle, a SEI film forms on the surface of the negative electrode in lithium-ion batteries. This film formation process consumes a significant amount of lithium ions, resulting in low initial efficiency. Currently, the most widely used graphite anode can suffer irreversible capacity loss of up to 10%, while for silicon-based anodes with high specific capacity, the loss can exceed 30%. Therefore, to compensate for the lithium consumed by the SEI film, lithium replenishment agents are needed to improve battery energy density and thus increase the driving range of electric vehicles.

[0003] Currently, lithium replenishment methods are divided into positive electrode lithium replenishment and negative electrode lithium replenishment. Negative electrode lithium replenishment primarily uses metallic lithium as the lithium source, such as lithium powder replenishment and lithium foil replenishment. Metallic lithium has high reactivity and readily reacts with gases such as water, oxygen, and carbon dioxide in the air. Therefore, negative electrode lithium replenishment has very high environmental requirements, necessitating significant investment in production line modifications. Positive electrode lithium replenishment, on the other hand, uses lithium metal oxides, which are more stable than metallic lithium and can be directly added during the positive electrode homogenization process, making it compatible with the positive electrode production line and effectively avoiding the aforementioned problems. The most common positive electrode lithium replenishment additives include Li5FeO4, Li2NiO2, Li2MnO3, Li6CoO4, Li6MnO4, and Li5ReO6. Most current lithium replenishment additives are synthesized using high-temperature solid-state methods, obtaining oxides through high-temperature decomposition. Because the commonly used raw materials are all solids with low activity, multiple calcinations are required, and the calcination time is long, generally tens of hours or more. Furthermore, prolonged high-temperature calcination leads to rapid growth in material particle size, resulting in phenomena such as excessively large particle size and agglomeration. It may even produce byproducts and residual alkali, as well as problems such as material particle breakage and shedding due to excessively large particle size during the recycling process.

[0004] Sodium-ion batteries primarily rely on the movement of sodium ions between the positive and negative electrodes to operate, similar to lithium-ion batteries. However, sodium-ion batteries also suffer from sodium ion loss and irreversible capacity loss during the first cycle. Therefore, the development of sodium replenishment agents is of great significance to the advancement of sodium-ion batteries. Summary of the Invention

[0005] This invention provides a method for preparing lithium or sodium supplementing materials, the resulting products, and their applications. The products prepared by the method provided by this invention have small particle size and low residual alkali.

[0006] To achieve the above objectives, the present invention provides a method for preparing lithium or sodium supplementation materials, comprising the following steps:

[0007] 1) The powder of N source is mixed with the powder of M source to obtain precursor powder; wherein the N source is at least one of the following: oxide, hydroxide, peroxide, inorganic salt and organic salt of lithium or sodium; wherein the M source is at least one of the following: oxide, hydroxide, sulfate, chlorate and nitrate of iron, nickel, cobalt, aluminum or manganese.

[0008] 2) The precursor powder is subjected to a first calcination and a second calcination in a vacuum environment to obtain lithium- or sodium-supplemented materials; the temperature of the first calcination is 700-1000℃ and the time is 1-5h, the temperature of the second calcination is 500-700℃ and the time is 3-5h, and the temperature of the first calcination is higher than the temperature of the second calcination.

[0009] Preferably, in step 1), when the N source is a lithium-containing material, the lithium-containing material is one or more of Li2O, LiOH, LiOH·H2O, Li2CO3, LiNO3, Li2C2O4 and CH3COOLi; when the N source is a sodium-containing material, the sodium-containing material is one or more of Na2O, NaOH, Na2CO3, NaNO3, Na2C2O4 and CH3COONa.

[0010] Preferably, the source M in step 1) is one or more of Fe2O3, Fe3O4, NiO, CoO, Al2O3, Mn2O3, FeC2O4, Fe(NO3)3·9H2O, Ni(NO3)2, Co(NO3)2·6H2O, Al(NO3)3·9H2O, Mn(NO3)2, FeCl3, NiCl2, AlCl3, MnCl3, Fe2(SO4)3, NiSO4, CoSO4, and Mn2(SO4)3.

[0011] Preferably, the particle sizes of the N-source powder and the M-source powder in step 1) are independently 0.1 to 10 μm.

[0012] Preferably, the mixing method in step 1) is ball milling or dissolving the N source powder and M source powder in a solvent and then spray drying; the ball milling speed is 300-600 r / min, the ball milling time is 2-6 h, and the ball milling ratio is 1-1.5:1.

[0013] Preferably, step 1) further includes compressing the precursor powder into tablets at a pressure of 0–500 bar for 0–10 min, resulting in a tablet density of 0–2 g / cm³. 3 .

[0014] Preferably, in step 3), the heating rate during the first calcination and the second calcination are independently 15-30℃ / min, and the cooling rate is independently 15-30℃ / min.

[0015] The present invention provides a lithium or sodium supplement material prepared by the method described in any one of the above-mentioned methods, wherein the particle size of the lithium or sodium supplement material is ≤5μm and the residual alkali content is ≤0.5wt%.

[0016] This invention provides the application of the aforementioned lithium or sodium supplementing material in the positive electrode of a battery, wherein the amount of the lithium or sodium supplementing material added is 1 to 5 wt% of the positive electrode active material.

[0017] Preferably, when the battery is a lithium-ion battery, the positive electrode active material is one or more of LiCoO2, LiFePO4, NCM and LMFP; when the battery is a sodium-ion battery, the positive electrode active material is one or more of transition metal oxides, polyanionic compounds and Prussian blue compounds.

[0018] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0019] The method provided by this invention utilizes vacuum sintering and a high-temperature primary calcination followed by a low-temperature secondary calcination to prepare lithium oxide. Lithium oxide exhibits high reactivity with water vapor, resulting in a highly reversible reaction. Conventional sintering requires prolonged passage of inert gas to remove water vapor and reduce the presence of lithium hydroxide. Lithium hydroxide exists in a molten state at high temperatures, but solidifies upon cooling, leading to agglomeration. Under vacuum conditions, the byproduct water vapor is removed promptly, promoting the forward reaction. The absence of lithium hydroxide results in a non-agglomerated, loose product, thus yielding a porous, non-agglomerated lithium / sodium supplement material. Simultaneously, the high-temperature primary sintering accelerates the reaction and synthesizes the lithium supplement material, while the reduced calcination time inhibits particle growth, resulting in small-particle-size lithium / sodium supplement materials. The low-temperature secondary sintering improves the purity of the lithium / sodium supplement material, reduces residual alkali, and also prevents particle size growth to a certain extent.

[0020] The material obtained by this invention has a small particle size, which reduces the need for additional crushing processes, avoids material deterioration, reduces energy consumption, and also avoids problems such as particle breakage and shedding caused by excessively large particle size in lithium / sodium replenishment materials during the recycling process. Attached Figure Description

[0021] Figure 1 The image shows a SEM image of Li2NiO2 prepared in Example 1. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] This invention provides a method for preparing lithium- or sodium-supplementing materials, comprising the following steps:

[0024] 1) The powder of N source is mixed with the powder of M source to obtain precursor powder; wherein the N source is at least one of the following: oxide, hydroxide, peroxide, inorganic salt and organic salt of lithium or sodium; wherein the M source is at least one of the following: oxide, hydroxide, sulfate, chlorate and nitrate of iron, nickel, cobalt, aluminum or manganese.

[0025] 2) The precursor powder is subjected to a first calcination and a second calcination in a vacuum environment to obtain lithium- or sodium-supplemented materials; the temperature of the first calcination is 700-1000℃ and the time is 1-5h, the temperature of the second calcination is 500-700℃ and the time is 3-5h, and the temperature of the first calcination is higher than the temperature of the second calcination.

[0026] This invention involves mixing N-source powder and M-source powder to obtain precursor powder. The N-source is at least one selected from lithium or sodium oxides, hydroxides, peroxides, inorganic salts, and organic salts. The M-source is at least one selected from iron, nickel, cobalt, aluminum, or manganese oxides, hydroxides, sulfates, chlorates, and nitrates. In this invention, the particle size of the N-source powder and the M-source powder is preferably 0.1–10 μm. In this invention, the N-source or M-source material can be processed to obtain the powder using methods such as ball milling, spray drying, air jet milling, vibratory milling, and mechanical crushing.

[0027] In this invention, when the N source is a lithium-containing material, the lithium-containing material is preferably one or more of Li2O, LiOH, LiOH·H2O, Li2CO3, LiNO3, Li2C2O4 and CH3COOLi, more preferably LiOH or LiOH·H2O; when the N source is a sodium-containing material, the sodium-containing material is one or more of Na2O, NaOH, Na2CO3, NaNO3, Na2C2O4 and CH3COONa.

[0028] In this invention, the M source is one or more of Fe2O3, Fe3O4, NiO, CoO, Al2O3, Mn2O3, FeC2O4, Fe(NO3)3·9H2O, Ni(NO3)2, Co(NO3)2·6H2O, Al(NO3)3·9H2O, Mn(NO3)2, FeCl3, NiCl2, AlCl3, MnCl3, Fe2(SO4)3, NiSO4, CoSO4, and Mn2(SO4)3, more preferably Fe2O3, NiO, CoO, Al2O3, or Mn2O3.

[0029] In this invention, the mixing method is preferably ball milling or dissolving the N-source powder and M-source powder in a solvent before spray drying; the ball milling speed is preferably 300-600 r / min, the ball milling time is preferably 2-6 h, and the ball-to-particle ratio is preferably 1-1.5:1. In this invention, when the N-source powder and M-source powder are easily hygroscopic raw materials, it is preferable to first dissolve them in a solvent before spray drying. In this invention, the solvent is preferably water; the spray drying temperature is preferably 150-250°C.

[0030] After obtaining the precursor, the present invention subjectes the precursor to a first calcination and a second calcination in a vacuum environment to obtain a lithium- or sodium-supplemented material. The first calcination temperature is 700–1000℃ for 1–5 hours, and the second calcination temperature is 500–700℃ for 3–5 hours, with the first calcination temperature being higher than the second calcination temperature. In the present invention, the vacuum environment has a vacuum degree ≥1*10⁻⁶. -5 Pa. In this invention, the heating rate during the first calcination and the second calcination are each preferably 15–30 °C / min, and the cooling rate is also preferably 15–30 °C / min. The relatively high heating / cooling rates used in this invention allow for faster attainment of the reaction temperature, reducing unnecessary heating / cooling times and minimizing spontaneous particle size growth caused by high temperatures.

[0031] In this invention, before calcination, the precursor powder is preferably compressed into tablets to obtain a block precursor. In this invention, the compression pressure is preferably 0–500 bar, more preferably 100–400 bar; the compression time is preferably 0–10 min, more preferably 1–6 min; and the tablet density is preferably 0–2 g / cm³. 3 More preferably, it is 1.1–1.5 g / cm³. 3 .

[0032] The method provided by this invention utilizes vacuum sintering, a high-temperature primary calcination, and a low-temperature secondary calcination to prepare lithium oxide. Lithium oxide exhibits high reactivity with water vapor, resulting in a highly reversible reaction. Conventional sintering requires prolonged passage of inert gas to remove water vapor and reduce the presence of lithium hydroxide. Lithium hydroxide exists in a molten state at high temperatures, but solidifies upon cooling, leading to agglomeration. Under vacuum conditions, the byproduct water vapor is removed promptly, promoting the forward reaction. The absence of lithium hydroxide results in a non-agglomerated, fluffy product. Furthermore, calcination under vacuum conditions allows for the timely removal of byproducts, further accelerating the forward reaction. Simultaneously, the high temperature of the first sintering accelerates the reaction, synthesizing the lithium-supplementing material, while reducing calcination time inhibits particle growth, yielding small-particle-size lithium / sodium-supplementing materials. The second sintering, performed at a low temperature, improves the purity of the lithium / sodium-supplementing material, reduces residual alkali, and also prevents particle size growth to a certain extent.

[0033] The present invention provides a lithium or sodium supplement material prepared by the method described in any one of the above-mentioned methods, wherein the particle size of the lithium or sodium supplement material is ≤5μm and the residual alkali content is ≤0.5wt%.

[0034] The material obtained by this invention has a small particle size, reducing the need for additional pulverization processes, preventing material deterioration, and reducing energy consumption. It also avoids problems such as particle breakage and shedding caused by excessively large particle sizes in lithium / sodium supplementation materials during cycling. Furthermore, the material obtained by this invention has low residual alkali, which reduces the occurrence of gelation during homogenization (high residual alkali refers to a strongly alkaline environment; under strong alkalinity, the strong alkali reacts with the hydrogen in PVDF to form a defluorination reaction, resulting in PVDF gelation). It also reduces side reactions between electrolytes.

[0035] This invention provides the application of the aforementioned lithium- or sodium-supplementing materials in the positive electrode of a battery, wherein the amount of the lithium- or sodium-supplementing material added is preferably 1-5 wt% of the positive electrode active material. In this invention, when the battery is a lithium-ion battery, the positive electrode active material is preferably one or more of LiCoO2, LiFePO4, NCM, and LMFP; the negative electrode active material is preferably at least one of natural graphite, artificial graphite, soft carbon, hard carbon, lithium titanate, silicon, silicon-carbon, and silicon oxide; when the battery is a sodium-ion battery, the positive electrode active material is preferably one or more of transition metal oxides, polyanionic compounds, and Prussian blue compounds; the negative electrode active material is preferably one or more of natural graphite, artificial graphite, hard carbon, and soft carbon.

[0036] To further illustrate the present invention, 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 scope of protection of the present invention.

[0037] Example 1

[0038] S1. LiOH·H2O and NiO with a particle size of 2-10 μm were placed in a ball mill jar at a lithium-nickel ratio of 2.25:1 and a ball mass ratio of 1.5. The mixture was ball milled at a speed of 600 r / min for 4 h to obtain precursor powder.

[0039] S2. Preparation of lithium-rich lithium nickelate material: The above precursor powder was pressed at a pressure of 500 bar for 1 min to obtain a compacted density of 1.2 g / cm³. 3 The sample was calcined in a vacuum atmosphere, and the vacuum gauge on the tube furnace showed a vacuum level of 1*10. - 5 Pa was heated to 800℃ at a rate of 20℃ / min and held for 2 hours, then cooled to 600℃ at a rate of 20℃ / min and held for 5 hours, and finally cooled to room temperature at a rate of 20℃ / min to obtain a Li₂NiO₂ product with a particle size of 1μm. Its SEM image is shown below. Figure 1 As shown, the purity of Li2NiO2 was determined to be 99.3%.

[0040] Example 2

[0041] S1. LiNO3 and Co(NO3)2·6H2O were dissolved in deionized water at a molar ratio of 6.5:1, heated and stirred at 65℃ for 4 hours, and then spray-dried (spray drying temperature was 200℃) to obtain precursor powder with a particle size of 2-10μm.

[0042] S2. Preparation of lithium-rich lithium cobalt oxide materials: The above precursor powder is calcined in a vacuum atmosphere (vacuum degree 1*10). -5 The temperature was increased to 900℃ at a rate of 15℃ / min and held for 1 hour. Then the temperature was decreased to 700℃ at a rate of 15℃ / min and held for 3 hours. Finally, the temperature was decreased to room temperature at a rate of 15℃ / min to obtain a Li6CoO4 product with a particle size of 1.5μm. The purity of Li6CoO4 was determined to be 98.9%.

[0043] Example 3

[0044] S1. Li2CO3 and Fe2O3 with a particle size of 2-10μm were placed into a ball mill jar at a lithium-iron ratio of 5.2:1 and a ball mass ratio of 1.5. The mixture was ball milled at a speed of 550r / min for 3.5h to obtain precursor powder.

[0045] S2. Preparation of lithium-rich lithium iron ferrite material: The above mixture was pressed at a pressure of 100 bar for 10 min to obtain a compacted density of 1.3 g / cm³. 3 The sample was calcined in a vacuum atmosphere (vacuum degree 1*10). -5The temperature was increased to 850℃ at a rate of 30℃ / min and held for 3 hours. Then the temperature was decreased to 500℃ at a rate of 30℃ / min and held for 5 hours. Finally, the temperature was decreased to room temperature at a rate of 30℃ / min to obtain a Li5FeO4 product with a particle size of 1.3μm. The purity of Li5FeO4 was determined to be 99.6%.

[0046] Example 4

[0047] S1. NaOH and Fe2O3 with a particle size of 2-10 μm are placed in a ball mill jar at a sodium-to-iron ratio of 11:1 and a ball mass ratio of 1.5. The mixture is ball milled at a speed of 500 r / min for 4.5 h to obtain precursor powder.

[0048] S2. Preparation of lithium-rich sodium ferrite material: The above precursor powder was pressed at a pressure of 300 bar for 5 min to obtain a compacted density of 1.4 g / cm³. 3 The sample was calcined in a vacuum atmosphere (vacuum degree 1*10). -5 The temperature was increased to 750℃ at a rate of 10℃ / min and held for 2 hours. Then, the temperature was decreased to 500℃ at a rate of 20℃ / min and held for 5 hours. Finally, the temperature was decreased to room temperature at a rate of 20℃ / min to obtain a Na5FeO4 product with a particle size of 1.9μm. The purity of Na5FeO4 was determined to be 98.5%.

[0049] Comparative Example 1

[0050] Powdered 2-10 μm LiOH and Fe2O3 were placed in a ball mill jar at a lithium-iron ratio of 11:1, with a pellet mass ratio of 1.5. The mixture was ball-milled at 500 r / min for 4.5 h to obtain a mixture. After mixing, the powder was calcined in an argon atmosphere, heated to 850 °C at a rate of 5 °C / min and held for 20 h, and then cooled to room temperature at a rate of 5 °C / min to obtain a Li5FeO4 product with a particle size of 300 μm. The purity of Li5FeO4 was determined to be 91.5%.

[0051] Comparative Example 2

[0052] LiOH·H₂O and NiO with a particle size of 2–10 μm were placed in a ball mill jar at a lithium-nickel ratio of 2.25:1 (bead mass ratio 1.5) and ball-milled at 600 r / min for 4 h to obtain precursor powder. The precursor powder was then calcined in an argon atmosphere, heated to 600 °C at a rate of 5 °C / min and held at that temperature for 30 h, and then cooled to room temperature at a rate of 5 °C / min to obtain Li₂NiO₂ product with a particle size of 350 μm. The purity of Li₂NiO₂ was determined to be 88.2%.

[0053] Comparative Example 3

[0054] Li₂O and CoO with particle sizes of 2–10 μm were placed in a ball mill jar at a lithium-cobalt ratio of 3.5:1 (bead mass ratio 1.5) and ball-milled at 600 r / min for 4 h to obtain a mixture. After mixing, the powder was calcined in an argon atmosphere, heated to 700 °C at a rate of 5 °C / min and held for 30 h, then cooled to room temperature at a rate of 5 °C / min to obtain a Li₆CoO₄ product with a particle size of 500 μm. The purity of Li₆CoO₄ was determined to be 91.8%.

[0055] Comparative Example 4

[0056] NaOH and Fe₂O₃ with a particle size of 2–10 μm were placed in a ball mill jar at a sodium-to-iron ratio of 11:1 (bead mass ratio 1.5) and ball milled at 500 r / min for 4.5 h to obtain precursor powder. The precursor powder was calcined in an argon atmosphere, heated to 800 °C at a rate of 5 °C / min and held at that temperature for 30 h, and then cooled to room temperature at a rate of 5 °C / min to obtain Na₅FeO₄ product with a particle size of 390 μm. The purity of Na₅FeO₄ was determined to be 91.3%.

[0057] Comparative Example 5

[0058] Except for the calcination being conducted under argon gas, all other test conditions were exactly the same as in Example 1. The specific procedures are as follows:

[0059] S1. LiOH·H2O and NiO with a particle size of 2-10 μm were placed in a ball mill jar at a lithium-nickel ratio of 2.25:1 and the mass ratio of the particles was 1.5. The mixture was ball milled at a speed of 600 r / min for 4 h to obtain the precursor powder.

[0060] S2. Preparation of lithium-rich lithium nickelate material: The above precursor powder was pressed at a pressure of 500 bar for 1 min to obtain a compacted density of 1.2 g / cm³. 3 The sample was calcined in an argon atmosphere, and the vacuum gauge on the tube furnace showed a vacuum level of 1*10. - 5 Pa was heated to 800℃ at a rate of 20℃ / min and held for 2 hours. Then, it was cooled to 600℃ at a rate of 20℃ / min and held for 5 hours. Finally, it was cooled to room temperature at a rate of 20℃ / min to obtain a Li2NiO2 product with a particle size of 5μm. The purity of Li2NiO2 was determined to be 88.1%.

[0061] Comparative Example 6

[0062] The difference from Example 1 lies in the heating / cooling rate, as detailed below:

[0063] S1. LiOH·H2O and NiO with a particle size of 2-10 μm were placed in a ball mill jar at a lithium-nickel ratio of 2.25:1 and the mass ratio of the particles was 1.5. The mixture was ball milled at a speed of 600 r / min for 4 h to obtain the precursor powder.

[0064] S2. Preparation of lithium-rich lithium nickelate material: The above precursor powder was pressed at a pressure of 500 bar for 1 min to obtain a compacted density of 1.2 g / cm³. 3 The sample was calcined in a vacuum atmosphere, and the vacuum gauge on the tube furnace showed a vacuum level of 1*10. - 5 Pa was heated to 800℃ at a rate of 5℃ / min and held for 2 hours. Then it was cooled to 600℃ at a rate of 5℃ / min and held for 5 hours. Finally, it was cooled to room temperature at a rate of 5℃ / min to obtain a Li2NiO2 product with a particle size of 100μm. The purity of Li2NiO2 was determined to be 93.7%.

[0065] Comparative Example 7

[0066] The difference from Example 1 is that a single sintering process is performed, as detailed below:

[0067] S1. LiOH·H2O and NiO with a particle size of 2-10 μm were placed in a ball mill jar at a lithium-nickel ratio of 2.25:1 and the mass ratio of the particles was 1.5. The mixture was ball milled at a speed of 600 r / min for 4 h to obtain the precursor powder.

[0068] S2. Preparation of lithium-rich lithium nickelate material: The above precursor powder was pressed at a pressure of 500 bar for 1 min to obtain a compacted density of 1.2 g / cm³. 3 The sample was calcined in a vacuum atmosphere, and the vacuum gauge on the tube furnace showed a vacuum level of 1*10. -5 Pa was heated to 800℃ at a rate of 20℃ / min, held at that temperature for 7 hours, and then cooled to room temperature at a rate of 20℃ / min to obtain a Li2NiO2 product with a particle size of 10μm. The purity of Li2NiO2 was determined to be 91.3%.

[0069] Comparative Example 8

[0070] The difference from Comparative Example 7 is that the sintering temperature is 600℃, and the specific operation is as follows:

[0071] S1. LiOH·H2O and NiO with a particle size of 2-10 μm were placed in a ball mill jar at a lithium-nickel ratio of 2.25:1 and the mass ratio of the particles was 1.5. The mixture was ball milled at a speed of 600 r / min for 4 h to obtain the precursor powder.

[0072] S2. Preparation of lithium-rich lithium nickelate material: The above precursor powder was pressed at a pressure of 500 bar for 1 min to obtain a compacted density of 1.2 g / cm³. 3 The sample was calcined in a vacuum atmosphere, and the vacuum gauge on the tube furnace showed a vacuum level of 1*10. -5 Pa was heated to 600℃ at a rate of 20℃ / min, held at that temperature for 7 hours, and then cooled to room temperature at a rate of 20℃ / min to obtain a Li2NiO2 product with a particle size of 13μm. The purity of Li2NiO2 was determined to be 75.3%.

[0073] Note: The lithium-iron ratio, lithium-nickel ratio, lithium-cobalt ratio, etc. mentioned in the examples and comparative examples are all measured in molar ratios.

[0074] Battery performance test

[0075] The lithium-supplementing material prepared in the examples and comparative examples was mixed with the positive electrode material LiCoO2 at a weight ratio of 5:100. A mixture of the lithium-supplementing material and the positive electrode active material, consisting of conductive carbon black (SP) and polyvinylidene fluoride (PVDF) at a weight ratio of 90:5:5, was used for the positive electrode material formulation. The negative electrode active material was graphite, and the lithium-ion electrolyte was 1.2 mol / L LiPF6 / EC–DMC (1:1). After formulation, the following steps were performed sequentially: homogenization, coating, roller forming, tab welding, winding, top sealing, electrolyte injection, and formation to obtain a lithium-ion battery.

[0076] The sodium supplement prepared in the examples and comparative examples was mixed with Prussian blue, the positive electrode material, at a weight ratio of 5:100. When preparing the positive electrode material, a mixture of sodium supplement and positive electrode active material (conductive carbon black (SP):polyvinylidene fluoride (PVDF)) was mixed at a weight ratio of 90:5:5. The negative electrode active material was graphite, and the sodium electrolyte was 1.2 mol / L NaPF6 / EC–DMC (1:1). After preparation, the following steps were performed sequentially: homogenization, coating, roller forming, tab welding, winding, top sealing, electrolyte injection, and formation to prepare the sodium-ion battery.

[0077] To further demonstrate the effectiveness of the product of the present invention, the products of the embodiments and comparative examples were added to a pouch battery for testing, and the specific results are shown in Table 1:

[0078] Table 1. Capacity retention rate after initial effect and 100 cycles

[0079]

[0080] As shown in Table 1, the small-particle-size, low-alkali-residue lithium / sodium-supplementing materials prepared in this invention, when used as additives in lithium-ion batteries, result in higher initial charge-discharge efficiency and capacity retention after 100 cycles compared to the comparative example. This indicates that the small-particle-size lithium supplement prepared in this invention can mix more evenly with the cathode material, allowing lithium ions to be fully extracted and utilized. The lithium / sodium-supplementing materials have a particle size range of 2-10 μm, thus avoiding problems such as material cracking and electrode detachment that could affect battery cycling. The resulting batteries achieved an initial charge-discharge efficiency of over 90% and a capacity retention of over 91% after 100 cycles.

[0081] Alkali value test

[0082] The residual alkali of the products from the examples and comparative examples was tested according to the lithium-ion battery cathode material testing method. The specific test results are shown in Table 2.

[0083] Table 2 Results of surface residual alkali

[0084] Residual alkali content (wt%) Example 1 0.48 Example 2 0.43 Example 3 0.49 Example 4 0.46 Comparative Example 1 5.35 Comparative Example 2 6.24 Comparative Example 3 5.83 Comparative Example 4 6.12 Comparative Example 5 6.64 Comparative Example 6 3.25 Comparative Example 7 3.52 Comparative Example 8 16.23

[0085] As can be seen from Table 2, the residual alkali value of the lithium / sodium supplement material prepared by this invention is significantly lower than that of the comparative example.

[0086] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a lithium or sodium supplement material, characterized in that, The method comprises the following steps: 1) mixing a powder of an N source with a powder of an M source to obtain a precursor powder; the N source is at least one of lithium or sodium oxides, hydroxides, peroxides, inorganic salts and organic salts; the M source is at least one of iron, nickel, cobalt, aluminum or manganese oxides, hydroxides, sulfates, chlorates and nitrates; 2) sequentially performing primary calcination and secondary calcination on the precursor powder in a vacuum environment to obtain a lithium or sodium supplement material; the temperature of the primary calcination is 700-1000 ℃, and the time is 1-5 h; the temperature of the secondary calcination is 500-700 ℃, and the time is 3-5 h; the temperature of the primary calcination is higher than that of the secondary calcination; The heating rate of the primary calcination and the secondary calcination in step 2) is independently 10 ℃ / min or 15-30 ℃ / min, and the cooling rate is independently 15-30 ℃ / min.

2. The production method according to claim 1, characterized by, In step 1), when the N source is a lithium-containing material, the lithium-containing material is one or more of Li2O, LiOH, LiOH•H2O, Li2CO3, LiNO3, Li2C2O4 and CH3COOLi; when the N source is a sodium-containing material, the sodium-containing material is one or more of Na2O, NaOH, Na2CO3, NaNO3, Na2C2O4 and CH3COONa.

3. The preparation method according to claim 1, characterized in that, In step 1), the M source is one or more of Fe2O3, Fe3O4, NiO, CoO, Al2O3, Mn2O3, FeC2O4, Fe(NO3)3·9H2O, Ni(NO3)2, Co(NO3)2·6H2O, Al(NO3)3·9H2O, Mn(NO3)2, FeCl3, NiCl2, AlCl3, MnCl3, Fe2(SO4)3, NiSO4, CoSO4 and Mn2(SO4)3.

4. The method of claim 1, wherein, In step 1), the particle size of the powder of the N source and the powder of the M source is independently 0.1-10 μm.

5. The preparation method according to claim 1, characterized in that, In step 1), the mixing mode is ball milling or dissolving the powder of the N source and the powder of the M source in a solvent and then spray drying; the rotation speed of the ball milling is 300-600 r / min, the ball milling time is 2-6 h, and the ball milling bead ratio is 1-1.5:

1.

6. The method of claim 1, wherein, In step 1) the precursor powder is also pressed into a tablet, the pressure is 0-500 bar, the time is 0-10 min, the tablet density is 0-2 g / cm 3 .

7. The lithium or sodium supplement material prepared by the method of any one of claims 1-6, characterized in that, The particle size of the lithium or sodium supplement material is ≤5 μm, and the residual alkali content is ≤0.5 wt%.

8. Use of the lithium or sodium supplementing material according to claim 7 in a cathode of a battery, characterized in that, The addition amount of the lithium or sodium supplement material is 1-5 wt% of the positive electrode active material.

9. Use according to claim 8, characterized in that, When the battery is a lithium ion battery, the positive electrode active material is one or more of LiCoO2, LiFePO4, NCM and LMFP; when the battery is a sodium ion battery, the positive electrode active material is one or more of transition metal oxides, polyanion compounds and Prussian blue.

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