Lithium carbonate lithium supplement and preparation method and application thereof

Abstract

The application provides a lithium carbonate lithium supplement agent and a preparation method and application thereof, and relates to the technical field of secondary batteries.The preparation method of the lithium carbonate lithium supplement agent comprises the following steps: reacting ethyl carbamate and lithium hydroxide monohydrate in water to obtain the lithium carbonate lithium supplement agent.The prepared lithium carbonate lithium supplement agent has a three-dimensional porous framework structure of lithium carbonate, and the decomposition voltage of the lithium carbonate is lower than that of the existing commercially available lithium carbonate, so that the lithium carbonate can be directly used as a lithium supplement agent in the preparation of lithium ion batteries without being compounded with other metals.The preparation method of the lithium carbonate lithium supplement agent is simple in operation, convenient in post-treatment of reaction products, and high in operability, and can efficiently obtain a high-performance lithium supplement agent material, and is suitable for large-scale production of lithium ion batteries.

Description

Technical Field

[0001] This invention relates to the field of secondary battery technology, specifically to a lithium carbonate lithium replenishing agent, its preparation method, and its application. Background Technology

[0002] In lithium-ion batteries, especially those using high-capacity electrode materials (such as silicon-based anodes and high-nickel cathodes), significant irreversible lithium loss during the first charge-discharge cycle is a key reason for low initial capacity, decreased coulombic efficiency, and shortened cycle life. Implementing effective lithium replenishment techniques has become a crucial step in improving battery energy density and long-term cycle stability.

[0003] Currently, lithium replenishment technologies are mainly divided into three categories: positive electrode lithium replenishment (doping lithium-rich materials into the positive electrode), negative electrode pre-lithiation (chemical or electrochemical lithiation pretreatment of the negative electrode), and electrolyte additive lithium replenishment (using sacrificial salts to decompose and release lithium ions in the early stages of charging). Among them, electrolyte additive lithium replenishment has received widespread attention due to its simple process and ease of integration into existing production lines.

[0004] Among numerous sacrificial salt additives, lithium carbonate (Li₂CO₃) stands out due to its low cost, good environmental stability, and high theoretical lithium replenishment capacity (>700 mAh g⁻¹). -1 Lithium carbonate, with its advantages such as high decomposition potential (>4.7V), is an ideal choice. Its mechanism involves oxidative decomposition at the positive electrode when charged to a certain potential, thereby replenishing the system with active lithium. However, lithium carbonate has a high decomposition potential (>4.7V), exceeding the typical operating window of lithium-ion batteries (<4.7V). This characteristic easily leads to 1) side reactions of the electrolyte under high voltage (such as solvent decomposition or excessive growth of the positive electrode interface film), and 2) degradation of the positive electrode structure. This not only reduces coulombic efficiency but may also accelerate battery aging, making it difficult to practically use as a pre-lithiation additive for lithium-ion batteries. Therefore, reducing the actual decomposition voltage of lithium carbonate is a key issue for its practical application.

[0005] Existing research focuses on controlling the particle morphology of lithium carbonate, using composite conductive additives, or introducing catalysts to reduce its decomposition voltage. However, these technologies face challenges such as: 1) complex preparation processes, including byproducts from high-energy ball milling, making large-scale production difficult; 2) poor stability, making effective storage difficult; and 3) the need to introduce transition metals, such as Co, which results in high economic costs. Further breakthroughs are urgently needed. Summary of the Invention

[0006] The research and development team of this invention aimed to provide an organic sacrificial salt with a low decomposition potential. They conducted research on sacrificial salts using ethyl carbamate and lithium hydroxide monohydrate as reaction raw materials. During the experiment, they unexpectedly discovered that reacting ethyl carbamate and lithium hydroxide monohydrate in water could produce lithium carbonate with a three-dimensional porous framework structure. Moreover, this lithium carbonate has a lower decomposition voltage than commercially available lithium carbonate and can be directly used as a sacrificial salt in the preparation of lithium-ion batteries without the need for compounding with other metals.

[0007] To achieve the above technical objectives, on the one hand, the present invention proposes a method for preparing a lithium carbonate supplement, the method comprising: reacting ethyl carbamate and lithium hydroxide monohydrate in water to obtain the lithium carbonate supplement.

[0008] The research team speculates that the reaction formula for the preparation method is as follows:

[0009]

[0010] The above technical solution includes: the CO bond in ethyl carbamate is broken, and the carbonyl group and oxygen are respectively attached to the hydroxyl and hydrogen in a water molecule, thereby generating carbamic acid and ethanol. The carbamic acid further reacts with LiOH to obtain the intermediate product. Based on the intermediate product, the CN base in the amide is also broken, and the -COOLi and -NH2 groups are respectively attached to the hydroxyl and hydrogen in a water molecule, thereby generating HO-(C=O)-OLi and NH3. HO-(C=O)-OLi further reacts with LiOH to obtain the lithium carbonate lithium supplement product. In addition, the research team found that in the actual reaction process, there are conditions where the reactions generating the intermediate and the target product occur simultaneously.

[0011] The preparation method of the lithium carbonate supplement of the present invention is simple in operation and can produce a lithium carbonate supplement with high specific surface area and high porosity content with a three-dimensional porous framework.

[0012] The exploratory experiments of this invention demonstrate the discovery process; the embodiments of this invention confirm the excellent performance of the lithium carbonate supplement of this invention.

[0013] Furthermore, the present invention explores and optimizes the amount of ethyl carbamate and lithium hydroxide monohydrate. Optionally, the molar ratio of ethyl carbamate to lithium hydroxide monohydrate is 1:(1~5). In an optional example of the present invention, the molar ratio of ethyl carbamate to lithium hydroxide monohydrate is 1:(1~3), preferably 1:(1~1.25).

[0014] It should be noted that there are no special requirements for the type of water used in this invention, and those skilled in the art can choose according to their needs. For example, the water used is deionized water.

[0015] Furthermore, this invention explores and optimizes the amount of water used. Optionally, the mass ratio of ethyl carbamate to water is 1:(30~100). Understandably, water is used as a solvent in the preparation method of this invention. By optimizing the amount of water used, post-processing operations can be simplified and process costs reduced. In an optional example of this invention, the mass ratio of ethyl carbamate to water is 1:(40~50), preferably 1:50.

[0016] Furthermore, this invention explores and optimizes the control conditions and dosages of the reaction. Optionally, the reaction temperature of the preparation method is 10~40℃, preferably 20~30℃; the reaction time is 5~24h, preferably 8~10h. The control conditions of the preparation method of this invention are easy to achieve, and the overall preparation process is highly operable. In an optional example of this invention, the preparation method is carried out at 25℃ for 6h. In an optional example of this invention, the reaction efficiency can be improved and the reaction time shortened by means of heating and reflux.

[0017] Furthermore, the preparation method further includes post-treatment of the reaction product; the post-treatment includes: after removing water from the reaction product, obtaining the lithium carbonate product through washing, solid-liquid separation, and drying. It should be noted that the present invention does not limit the operation of removing water from the reaction product; for example, water and its dissolved byproducts can be removed by distillation, rotary evaporation, etc., and this does not limit the scope of protection of the present invention. The specific method of solid-liquid separation is not limited in the present invention; it can be carried out by filtration, centrifugation, etc., and those skilled in the art can choose appropriate operating methods as needed.

[0018] Furthermore, an organic solvent is used for the washing operation; the organic solvent includes at least one of anhydrous ethanol, diethyl ether, toluene, ethyl acetate, and acetone, preferably anhydrous ethanol.

[0019] Furthermore, the present invention does not limit the specific control conditions of the operation, and drying at 40~80℃ for 8~24h is optional.

[0020] On the other hand, the present invention proposes a lithium carbonate supplement, which is prepared by the above-mentioned method for preparing lithium carbonate supplement.

[0021] The lithium carbonate supplement of this invention features high porosity with high pore volume and low specific surface area, significantly increasing the number of chemical reaction sites and thus optimizing electrochemical reaction kinetics. Examples demonstrate that the lithium carbonate of this invention can be directly used as a lithium supplement in the preparation of lithium-ion batteries, effectively reducing the process cost and preparation difficulty of lithium-ion batteries, and possessing significant application value.

[0022] In a further example of the present invention, the specific surface area of ​​the lithium carbonate supplement is 18-25 m². 2 / g, total pore volume is 0.10~0.18cm³ 3 / g. Optionally, the mesopore content of the lithium carbonate replenishing agent accounts for 70%~99% of the total pore volume. The lithium carbonate replenishing agent of the present invention contains abundant mesopores and macropores in its structure. The macropore network promotes rapid electrolyte wetting and uniform distribution of conductive agents, increases reactive sites, shortens the lithium ion diffusion path, accelerates the oxidation decomposition reaction of lithium carbonate during charging, and makes lithium ion release more efficient and concentrated in a lower potential range. Macropores can provide the main channels for rapid electrolyte penetration and provide more conductive agent contact sites, improve the intrinsic insulation properties of lithium carbonate, and reduce ion diffusion resistance. By combining an appropriate proportion of macropore content with mesopore content, a high surface area can be provided, and the replenishment efficiency can be improved, promoting more uniform release of lithium ions at the interface. This helps to reduce the effective oxidation potential of the lithium carbonate replenishing agent of the present invention, reduce high-voltage side reactions (such as electrolyte solvent decomposition or excessive growth of the positive electrode interface film), and effectively compensate for irreversible lithium loss during lithium-ion battery cycling. In a further example of the present invention, the mesopore and macropore content of the lithium carbonate supplement accounts for 80% to 98.6% of the total pore volume. In an optional example of the present invention, the mesopore and macropore content of the lithium carbonate supplement accounts for 98.6% of the total pore volume.

[0023] In a further example of the present invention, the average pore size of the lithium carbonate supplement is 10~60 nm. The lithium carbonate supplement of the present invention can form an efficient ion transport channel, shorten the lithium ion diffusion path, and its pore size range takes into account both electrolyte permeability and structural stability, avoiding the disadvantages of easy clogging due to too small pore size and insufficient specific surface area due to too large pore size, thereby effectively reducing oxidation potential, improving lithium supplementation efficiency and uniformity, and suppressing high voltage side reactions.

[0024] In a further example of the present invention, the microstructure of the lithium carbonate supplement is a three-dimensional porous framework formed by the directional stacking of submicron sheet structure units; the structure unit has a symmetrical structure that is thick in the middle and thin at both ends, with the thickness of the middle region being 200~500 nm and the thickness ratio of the middle region to the end region being ≥2, which is more conducive to the structure units forming an angle through edge contact, thereby obtaining a three-dimensional porous framework structure with porosity.

[0025] It should be noted that the present invention does not limit the cross-sectional shape of the structural unit. In a further example of the present invention, the maximum planar dimension of the structural unit is 1~5μm. Here, the maximum planar dimension refers to the maximum linear length of the sheet structure in the projection plane, that is, the longest distance connecting any two points on the sheet contour. In a further example of the present invention, the included angle between adjacent structural units is 5°~90°.

[0026] On the other hand, this invention proposes the application of the aforementioned lithium carbonate replenishing agent in lithium battery manufacturing. Optionally, the lithium carbonate replenishing agent is used to decompose and provide an additional active lithium source during the first charging process of a lithium-ion battery to compensate for lithium loss during battery cycling.

[0027] Compared with existing technologies, the beneficial effects of this invention are as follows: The lithium carbonate supplement of this invention has a three-dimensional porous framework formed by the directional stacking of submicron sheet-like structural units, with high specific surface area, high total pore volume, and mesopore and macropore content reaching 70%~99%. Furthermore, it has a low decomposition voltage and can be directly used in the preparation of lithium-ion batteries to provide additional lithium ions to the battery system. It can effectively suppress high-voltage side reactions such as electrolyte decomposition and excessive growth of the positive electrode interface film, significantly suppressing battery capacity decay, extending cycle life, and reducing process costs.

[0028] The method for preparing lithium carbonate supplementary lithium agent of the present invention is simple to operate, convenient to process the reaction product, highly operable, and can efficiently obtain high-performance supplementary lithium agent materials, which is suitable for the large-scale production of lithium-ion batteries. Attached Figure Description

[0029] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0030] Figure 1 The XRD pattern of the lithium carbonate supplement of the present invention is shown and compared with the Li2CO3 standard card.

[0031] Figure 2 The image shows a SEM comparison between the lithium carbonate supplement of the present invention and commercially available lithium carbonate. Wherein a and b are commercially available lithium carbonate; c and d are the lithium carbonate supplement prepared in Example 1 of this invention.

[0032] Figure 3 The diagram shows a comparison of the pore structure analysis of the lithium carbonate supplement of the present invention and commercially available lithium carbonate. (a) shows the nitrogen adsorption-desorption test results, (b) shows the pore structure analysis results based on the BET model, and (c) shows the pore structure analysis results based on the BJH model.

[0033] Figure 4 Electrochemical tests of the lithium carbonate supplement of the present invention and commercially available lithium carbonate are shown: (a) voltage-specific capacity curve, (b) dQ / dV-voltage curve. Detailed Implementation

[0034] To facilitate understanding of the present invention, a more comprehensive description will be provided below, along with preferred embodiments. However, it should be understood that these embodiments are merely for more detailed explanation and should not be construed as limiting the invention in any way, i.e., not intended to limit the scope of protection of the invention.

[0035] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which this invention pertains. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.

[0036] Furthermore, it should be noted that although the various steps of the preparation method of the present invention are described in a specific order in the description of the present invention, these orders are not restrictive. Without departing from the basic principles of the present invention, those skilled in the art can perform the steps in different orders.

[0037] All numerical designations, such as temperature, time, length, and range, are approximate values. It should be understood that, while not always explicitly stated, all numerical designations are preceded by the term "approximately." It should also be understood that, while not always explicitly stated, the reagents described herein are merely examples, and their equivalents are known in the art.

[0038] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1–5” is disclosed, the described range should be interpreted as including ranges “1–4”, “1–3”, “1–2”, “1–2 and 4–5”, “1–3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0039] Exploration Example

[0040] Given the relatively high effective oxidation potential, complex preparation methods, and the need for compounding with precious metals in the application of existing inorganic sacrificial salts, the research team of this invention is committed to developing an organic sacrificial salt (OSS) and precisely controlling its decomposition thermodynamics by strategically selecting functional groups (such as introducing electron-donating groups such as methyl and methoxy groups to effectively reduce the decomposition voltage), thereby reducing the effective oxidation potential.

[0041] To achieve the above objectives, the research team conducted research on organic sacrificial salts using ethyl carbamate and lithium hydroxide monohydrate as reactants. Before the formal experiments, the team precisely calculated the theoretical specific capacity of the target organic sacrificial salt. The specific exploration process is as follows:

[0042] First: Weigh ethyl carbamate and lithium hydroxide monohydrate in a molar ratio of 1:0.85, add them to 20 mL of deionized water, and stir at room temperature (about 25°C) for 8 h; after the reaction is complete, evaporate the water; then add anhydrous ethanol (about 20~40 mL), wash / sonicate for 20 min; filter; dry at 60°C (about 8 h) to obtain a lithium salt.

[0043] Subsequently, the research team used the obtained lithium salt to prepare a positive electrode sheet, assembled a half-cell, and conducted charge-discharge tests, obtaining a first-cycle charge specific capacity of >700 mA h / g. Surprisingly, this first-cycle charge specific capacity is far higher than the theoretical specific capacity (400 mA h / g) of the target lithium salt, lithium carbamate. Further analysis of the XRD data of the obtained lithium salt ultimately confirmed that the prepared lithium salt is the inorganic sacrificial salt lithium carbonate.

[0044] Based on the findings of this exploratory experiment, the research and development team proposed the technical solution of this invention.

[0045] Example 1

[0046] A method for preparing a lithium carbonate supplement includes: weighing ethyl carbamate and lithium hydroxide monohydrate in a molar ratio of 1:1.25, adding them to 20 mL of deionized water, and stirring at room temperature (approximately 25°C) for 8 h; after the reaction is complete, evaporating the water; then adding anhydrous ethanol (approximately 20-40 mL), washing / sonicating for 20 min; filtering; and drying at 60°C (approximately 8 h) to obtain the lithium carbonate supplement.

[0047] Furthermore, the XRD pattern of the prepared lithium carbonate lithium supplement was tested in this embodiment. Figure 1 It can be confirmed that the X-ray diffraction pattern of the lithium carbonate supplement in this embodiment is consistent with the lithium carbonate standard PDF card (PDF#97-001-6713). No characteristic diffraction peaks of urethane and lithium hydroxide were detected, indicating that the raw material has been completely converted or removed within the XRD detection limit (about 1 wt%), and the sample is high-purity lithium carbonate.

[0048] Furthermore, in this embodiment, the commercially available lithium carbonate product (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., CAS No.: 554-13-2) and the prepared lithium carbonate were characterized by scanning electron microscopy (SEM).

[0049] like Figure 2 As shown, the lithium carbonate supplement of the present invention has a significantly different microstructure from commercially available lithium carbonate. The microstructure of commercially available lithium carbonate is an irregular blocky accumulation, while the microstructure of the lithium carbonate supplement of the present invention is a three-dimensional porous framework formed by the directional stacking of submicron sheet structure units.

[0050] Optionally, the structural unit has a symmetrical structure that is thick in the middle and thin at both ends, wherein the thickness of the middle region is 200~500nm and the thickness ratio of the middle region to the end region is ≥2.

[0051] Optionally, the maximum planar dimension of the structural unit is 1~5μm. It should be noted that the present invention does not limit the cross-sectional shape of the structural unit; it can be rhomboid, trapezoidal, polygonal, etc., and this does not limit the scope of protection of the present invention.

[0052] Optionally, the included angle between adjacent structural units is 5° to 90°, thereby forming a rich porous structure through the angled stacking of the unit structures.

[0053] Furthermore, in this embodiment, the pore structures of the lithium carbonate supplement and commercially available lithium carbonate in this embodiment were characterized using an Automated Gas sorption Analyzer (2011) at a test temperature of 150°C. Specifically, 300 mg each of the commercial and Example 1 lithium carbonate supplement powders were taken and vacuum-dried at 60°C for 12 h, followed by nitrogen adsorption-desorption tests. The results are as follows: Figure 3 As shown in Tables 1 and 2.

[0054] From Table 1 and Figure 3 It can be verified that the lithium carbonate supplement of this invention has a significantly different pore structure from commercially available lithium carbonate: as can be seen from the isotherm curves ( Figure 3 a) and aperture distribution ( Figure 3 (b) It can be seen that both materials conform to the characteristic curve of type I, confirming that both contain microporous structures; in addition, the lithium carbonate supplement of the present invention exhibits additional type IV hysteresis loop characteristics, proving that it has more obvious mesoporous structures; BJH data ( Figure 3 c) This further confirms that the lithium carbonate supplement of the present invention has a significantly increased mesoporous (2~50 nm) and macroporous (above 50 nm) structure.

[0055] Table 1 Summary of Volume / Area

[0056]

[0057] Table 2 Summary of BJH Adsorption-Desorption Curves

[0058]

[0059] Furthermore, in this embodiment, the mesoporous content of lithium carbonate is 24% and the macroporous content is 74%; while commercially available lithium carbonate has a mesoporous content of 10% and a macroporous content of 20%.

[0060] Furthermore, this embodiment also tested the electrochemical characteristics of the lithium carbonate supplement of this embodiment and commercially available lithium carbonate.

[0061] Electrode preparation: Weigh commercially available or Example 1 lithium carbonate supplement, conductive agent (ECP), and polyvinylidene fluoride (PVDF) in a mass ratio of 6:3:1 into an agate mortar, grind for 30-60 min, and add NMP (0.05 ml mg). -1 The positive electrode slurry was prepared by mixing the materials evenly. Then, two types of lithium carbonate positive electrode sheets were obtained by coating, drying, and cutting.

[0062] Subsequently, Li₂CO₃||Li were assembled separately, and constant current charge-discharge tests and dQ / dV curve analysis were performed. The constant current charge-discharge test operating conditions were a charging cutoff voltage of 4.7V and a current of 0.1C. The first charge-discharge curve was used to evaluate the initial coulombic efficiency. The constant current charge-discharge data were differentiated from the voltage (V) according to capacity (Q) to obtain the differential capacity curve (dQ / dV vs V). The results are shown below. Figure 4 .

[0063] Charge-discharge tests revealed that, at a charging cutoff voltage of 4.7 V, its specific capacity reached 697 mAh g. -1 This is equivalent to 96.27% of the theoretical value, far exceeding the 293 mAh g of commercially available lithium carbonate. -1 The 40.47% decomposition rate indicates that the lithium carbonate supplement of this invention can more fully release active lithium ions, significantly enhancing the initial coulombic efficiency and capacity contribution of the battery. Meanwhile, the oxidation peak potential in the dQ / dV curve is as low as 4.285 V (commercially available products >4.6 V), and the lithium carbonate decomposition range is 4.1-4.7 V. 4.285 V can be understood as the voltage at which the decomposition rate is fastest. Figure 4 (b) It was confirmed that the decomposition reaction can be triggered at relatively low voltages, effectively suppressing high-voltage side reactions, reducing electrolyte oxidation losses, and promoting the formation of a more uniform and stable solid electrolyte interphase (SEI) film. The research team speculates that the lithium carbonate supplement of this invention possesses unique pore structure characteristics, effectively improving electrolyte wettability and lithium-ion diffusion kinetics, enabling the material to achieve more efficient decomposition behavior during the first charge; thus, it not only significantly improves the utilization rate of the supplement but also improves the cycle stability and energy efficiency of the battery by lowering the reaction energy barrier. The lithium carbonate supplement of this invention exhibits significant technical advantages as a supplement in lithium-ion batteries.

[0064] Example 2

[0065] A method for preparing a lithium carbonate supplement includes: weighing ethyl carbamate and lithium hydroxide monohydrate in a molar ratio of 1:1.5, adding them to 60 mL of deionized water, and stirring at 22°C for 5 h; after the reaction is complete, evaporating to dryness; then adding diethyl ether (approximately 20-40 mL), washing / sonicating for 20 min; filtering; and drying at 60°C (approximately 5 h) to obtain the lithium carbonate supplement. The purity of the lithium carbonate supplement prepared in this example is 99%; the specific surface area of ​​the lithium carbonate is tested to be 10.15 m². 2 / g, total pore volume is 0.12cm³ 3 / g, mesoporous content accounts for 40% of the total pore volume, and macroporous content accounts for 50% of the total pore volume.

[0066] Example 3

[0067] A method for preparing a lithium carbonate supplement includes: weighing ethyl carbamate and lithium hydroxide monohydrate in a molar ratio of 1:1, adding them to 30 mL of deionized water, and stirring at 22 °C for 5 h; after the reaction is complete, evaporating to dryness; then adding anhydrous ethanol (approximately 10-60 mL), washing / sonicating for 20 min; filtering; and drying at 60 °C (approximately 6 h) to obtain the lithium carbonate supplement. The purity of the lithium carbonate supplement prepared in this example is 99%; the specific surface area of ​​the lithium carbonate is tested to be 10.2 m². 2 / g, total pore volume is 0.12 cm³ 3 / g, mesoporous content accounts for 30% of the total pore volume, and macroporous content accounts for 60% of the total pore volume.

[0068] Example 4

[0069] A method for preparing a lithium carbonate supplement includes: weighing ethyl carbamate and lithium hydroxide monohydrate in a molar ratio of 1:3, adding them to 60 mL of deionized water, and stirring at 22°C for 12 h; after the reaction is complete, evaporating to dryness; then adding anhydrous ethanol (approximately 30-60 mL), washing / sonicating for 20 min; filtering; and drying at 60°C (approximately 6 h) to obtain the lithium carbonate supplement. The purity of the lithium carbonate supplement prepared in this example is 99%; the specific surface area of ​​the lithium carbonate is tested to be 10.09 m². 2 / g, total pore volume is 0.125 cm³ 3 / g, mesoporous content accounts for 35% of the total pore volume, and macroporous content accounts for 50% of the total pore volume.

[0070] Example 5

[0071] A method for preparing a lithium carbonate supplement includes: weighing ethyl carbamate and lithium hydroxide monohydrate in a molar ratio of 1:3, adding them to 60 mL of deionized water, and stirring at 22°C for 12 h; after the reaction is complete, evaporating to dryness; then adding anhydrous ethanol (approximately 40-80 mL), washing / sonicating for 20 min; filtering; and drying at 60°C (approximately 6 h) to obtain the lithium carbonate supplement. The purity of the lithium carbonate supplement prepared in this example is 99%; the specific surface area of ​​the lithium carbonate is tested to be 9.2 m². 2 / g, total pore volume is 0.11cm 3 / g, mesopores account for 40% of the total pore volume, and macropores account for 30% of the total pore volume.

[0072] It should be noted that the above description, in conjunction with specific embodiments, provides a further detailed explanation of the present invention, and should not be construed as limiting the specific implementation of the invention to these descriptions. For those skilled in the art, several simple modifications can be made without departing from the concept of the present invention, and all such modifications should be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a lithium carbonate lithium supplement, characterized in that, The preparation method includes: reacting ethyl carbamate and lithium hydroxide monohydrate in water to obtain a lithium carbonate supplement with a three-dimensional porous framework structure; the molar ratio of ethyl carbamate and lithium hydroxide monohydrate is 1:(1~5); the reaction temperature of the preparation method is 10~40℃; and the reaction time is 5~24h.

2. The method for preparing the lithium carbonate lithium supplement according to claim 1, characterized in that, The mass ratio of ethyl carbamate to water is 1:(30~100).

3. The method for preparing the lithium carbonate lithium supplement according to claim 1, characterized in that, The preparation method further includes post-processing of the reaction product; the post-processing includes: after removing water from the reaction product, obtaining lithium carbonate product by washing, solid-liquid separation and drying.

4. The method for preparing the lithium carbonate lithium supplement according to claim 3, characterized in that, The washing operation is performed using an organic solvent; the organic solvent includes at least one selected from anhydrous ethanol, diethyl ether, toluene, ethyl acetate, and acetone. And / or, the drying operation is performed at a temperature of 40~80℃ for a time of 8~24h.

5. A lithium carbonate lithium supplement, characterized in that, The lithium carbonate supplement is prepared by the method described in any one of claims 1-4.

6. The lithium carbonate lithium supplement agent according to claim 5, characterized in that, The specific surface area of ​​the lithium carbonate supplement is 9~15m². 2 / g, total pore volume is 0.10~0.18cm³ 3 / g; And / or, the average pore size of the lithium carbonate supplement is 10~90 nm.

7. The lithium carbonate lithium supplement agent according to claim 5, characterized in that, The lithium carbonate lithium supplement has a microstructure of a three-dimensional porous framework formed by the directional stacking of submicron sheet structure units; the structure unit has a symmetrical structure that is thick in the middle and thin at both ends, with the thickness of the middle region being 200~500nm and the thickness ratio of the middle region to the end region being ≥2.

8. The application of the lithium carbonate lithium supplement agent according to any one of claims 5-7 in the preparation of lithium batteries.

Images