Lithium carboxymethyl cellulose with high lithium content and preparation method thereof

Abstract

The invention relates to the technical field of cellulose ether preparation, in particular to lithium carboxymethyl cellulose with high lithium content and a preparation method thereof. The preparation method of the lithium carboxymethyl cellulose with high lithium content comprises the following steps: crushing refined cotton, and mixing the crushed refined cotton with an isopropanol aqueous solution to form slurry; dissolving a lithium source in an isopropanol aqueous solution to form alkali liquor; dissolving chlorosuccinic acid in an isopropanol aqueous solution to form an etherifying agent solution; adding urea and the slurry into alkali liquor, and carrying out alkalization reaction; dropwise adding the etherifying agent solution, and carrying out an etherification reaction after a preliminary reaction; and after the reaction is finished, neutralizing, centrifuging, carrying out stepped washing by adopting ethanol with different concentrations, drying and crushing to obtain a lithium carboxymethyl cellulose product. According to the invention, the chlorosuccinic acid is used as the etherifying agent, the urea is used as the activating agent, and the process parameters are optimized, so that the prepared carboxymethyl cellulose lithium has high lithium content, high substitution degree and high viscosity, and is suitable for the high-performance lithium ion battery negative electrode binder.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cellulose ether preparation, and particularly relates to high-lithium-content carboxymethyl cellulose lithium and a preparation method thereof. BACKGROUND

[0002] The lithium content of traditional carboxymethyl cellulose lithium (CMC-Li) is low, and the reaction of a conventional etherifying agent (chloroacetic acid) is limited. The chloroacetic acid monosodium is only reacted with one molecule of lithium hydroxide, and only one carboxyl group carries lithium when introduced.

[0003] It is difficult to prepare a high-lithium-content product, which leads to insufficient lithium supplementing effect of carboxymethyl cellulose lithium as a negative electrode binder of a lithium battery. The product prepared by an acidification-lithiation two-step method has a high concentration of impurity ions (Na + ), which can form gel particles, reduce the uniformity of slurry, and cause lithium precipitation in a battery. Secondly, the viscosity of carboxymethyl cellulose lithium produced by a conventional method is low, which cannot meet the requirements of high-performance lithium ion batteries on slurry dispersibility and stability.

[0004] Therefore, a carboxymethyl cellulose lithium product with high lithium content, high purity and high viscosity is crucial to improving the performance of a battery. As a water-based binder for a negative electrode of a lithium ion battery, carboxymethyl cellulose lithium plays three key roles in battery manufacturing: (1) dispersing negative electrode active materials and supplementing lithium; (2) assisting in bonding negative electrode active materials and current collectors; and (3) thickening and preventing negative electrode slurry from settling. High-lithium-content CMC-Li can significantly increase the number of lithium ions that can freely move in a battery, reduce the diffusion distance of lithium ions to the surface of active materials, improve the efficiency of lithium extraction from positive and negative electrode materials, and thus improve the charge and discharge capacity and cycle performance of the battery.

[0005] 1. Acidification-lithiation two-step method (Meishan Jingrui, Chinese patent application for invention CN118684786A) ① Limitations of strong acid use This process uses 30-80wt% of hydrochloric acid, sulfuric acid or nitric acid in the acidification step, which is easy to damage equipment due to strong corrosion, and a large amount of alkaline substances need to be consumed during neutralization, increasing the cost.

[0006] In addition, strong acid treatment can lead to cellulose degradation, and although the product has high viscosity, the number of gel particles is relatively large, which affects the uniformity of the product.

[0007] ② Insufficient control of lithium content and impurities The highest lithium content of the product obtained by this method is only 4.4wt%, which is lower than 5.3wt% of the slurry method; the sodium content is 0.05-0.09wt%, which is better than the comparative example, but there is still residual sodium ion, which may affect the electrochemical performance of the lithium battery.

[0008] 2. Water control lithium method (Gansu Juncheng Huitong, Chinese invention patent application CN118359735A) The process is complex and energy-consuming, and it is necessary to first acidify CMC-Na to generate CMC-H, and then dry it to a water content of 10-30%. After the subsequent lithium reaction, multiple washing and drying are required, the process is long, and repeated drying steps increase energy consumption.

[0009] The acidification liquid uses strong acids such as concentrated sulfuric acid and concentrated hydrochloric acid, and the acidification process may produce acidic wastewater containing sodium sulfate, which is difficult to handle. Compared with the etherification reaction using chloroacetic acid, the degree of substitution of the product may be reduced when using certain new etherifying agents for etherification reaction. In addition, ethanol or acetone is used as an inhibitor in the lithium reaction, and the concentration needs to be higher than the swelling critical point by 2-10%. The amount of organic solvent used is large, the recovery cost is high, and there are safety hazards. SUMMARY

[0010] In view of the above deficiencies of the prior art, the purpose of the present application is to provide a carboxymethyl cellulose lithium with high lithium content and a preparation method thereof.

[0011] To achieve the above purpose, the technical solution adopted is: One of the purposes of the present application is to provide a preparation method of carboxymethyl cellulose lithium with high lithium content, comprising the following steps: (1) Raw material pretreatment: finely grinding refined cotton to 60-100 mesh to form cellulose powder, mixing with isopropyl alcohol aqueous solution with a mass fraction of 70-98% to form a slurry, the amount of isopropyl alcohol involved in the infiltration can ensure that the refined cotton cellulose is uniformly dispersed in the lye; Dissolve the lithium source in isopropyl alcohol aqueous solution with a mass fraction of 70-95% to prepare a lye with a concentration of 3-10%, which is denoted as solution 1; Dissolve chlorosuccinic acid in isopropyl alcohol aqueous solution to prepare a solution with a mass concentration of 50-70%, which is denoted as solution 2; (2) Alkalization reaction: add 3-10% of urea based on the mass of cellulose and the slurry of step (1) to solution 1, and stir at 15-40°C for 50-120 minutes under nitrogen protection; (3) Etherification reaction: slowly add solution 2 to the system after alkalization reaction, stir uniformly, then warm up to 70-85°C at a rate of 1-2°C / min, and react for 30-60 minutes; (4) Post-treatment: cool the reaction solution to 30-55°C, neutralize with dilute hydrochloric acid to pH 6.5-8.5, centrifuge, and then use ethanol with a concentration from low to high (60%-80%) for step-by-step washing, centrifuge, and then vacuum dry at 80-100°C, crush and sieve to obtain white powder carboxymethyl cellulose lithium (CMC-Li) product.

[0012] Preferably, the lithium source is at least one of lithium hydroxide, lithium ethoxide, lithium carbonate.

[0013] Preferably, the alkalization reaction in step (2) is carried out at 25℃.

[0014] Preferably, in the etherification reaction in step (3), the temperature is raised to 75℃ at a rate of 1-2℃ / min.

[0015] More preferably, the α-cellulose content of the purified cotton in step (1) is greater than 95%.

[0016] Preferably, the mass ratio of isopropyl alcohol to cellulose powder during the entire preparation process is 10-20:1.

[0017] The second object of the present application is to provide a high lithium content carboxymethyl cellulose lithium, which is prepared by the preparation method of the high lithium content carboxymethyl cellulose lithium, has a purity of ≥99.5%, a lithium content of 5.0-5.3wt%, a degree of substitution of 1.09-1.22, and a 1% aqueous solution viscosity of ≥2000 cP.

[0018] Compared with the prior art, the present application has the following beneficial effects: The etherification agent uses a dicarboxylic acid etherification agent, which uses its dicarboxylic acid groups to increase the degree of substitution and the reaction rate. There are three hydroxyl hydrogens on cellulose that can be substituted, which makes chlorosuccinic acid have a higher lithium content at a lower degree of substitution. The use of urea activator increases the reaction degree, making the alkalization and etherification reactions more complete, and significantly improving the lithiation efficiency. The segmented temperature control avoids the occurrence of side reactions and ensures the uniformity of the reaction substitution. Process parameter optimization: the use of a mixed solvent system of isopropyl alcohol / water achieves the best balance between the solubility of the reactants and the reaction rate at this ratio, reducing the solvent consumption ratio. The slurry method can produce products with higher degrees of substitution.

[0019] Producing high lithium content carboxymethyl cellulose lithium means higher lithium ion concentration, which can directly result in higher ionic conductivity. This is very beneficial for the rapid transmission of ions inside the battery, reducing internal resistance, and improving rate performance (fast charging and discharging ability). The second point is that good solubility is very important for uniform dispersion in the electrolyte, forming a stable electrode slurry, and promoting ion transmission inside the electrode. The third point is that high lithium content will cause the viscosity of Li-CMC solution to be relatively stable, and the relatively stable viscosity helps to prepare electrode slurry with better flowability, which is convenient for uniform coating. The fourth point is that Li-CMC contains a large number of lithium ions, which may be beneficial for participating in the formation of a more stable or more beneficial solid electrolyte interface film on the surface of the negative electrode (such as silicon, graphite), and can also remove excess impurity ions (especially Na +The side reactions caused by these impurity ions are easy to form gel particles, reduce the uniformity of the slurry, and cause lithium precipitation problems in the battery.

[0020] 1. Process efficiency and energy consumption optimization The slurry method does not require a two-step operation of acidification and then lithiation, but directly increases the lithium content through alkalization (urea activation) + etherification (chlorosuccinic acid) in one step, shortening the process by more than 30% and reducing energy consumption by 20% (compared to the multiple drying steps of Gansu Poly Energy Wisdom). Using segmented temperature control, the reaction rate is significantly improved compared to the constant temperature reaction (30-45℃) of Meishan Crystal, and the etherification time is shortened from 3-4 hours to 2.5 hours, and the degradation of cellulose caused by local overheating is avoided.

[0021] 2. Environmental protection and cost advantage The slurry method does not use strong acid acidification, and only uses LiOH and urea in the alkalization stage. The acidity of the etherification agent chlorosuccinic acid is weaker than that of sulfuric acid / nitric acid, and only a small amount of hydrochloric acid is needed to adjust the pH during neutralization, reducing the wastewater treatment cost by 50% (compared to the strong acid circulation process of Gansu Poly Energy Wisdom). Isopropyl alcohol is used as the reaction medium (concentration 70-98%), and the amount is 8 times the mass of cellulose, which is 20% less than the amount of ethanol used by Meishan Crystal (1:10-18), and the isopropyl alcohol recovery process is simpler, with a cost reduction of 30%. 3. Significant improvement in product performance The slurry method destroys the crystalline structure of cellulose through urea activation, with a lithium content of 5.0-5.3wt% (compared to 4.4wt% of Meishan Crystal), and a degree of substitution of 1.10-1.22, which is more suitable for lithium battery lithium supplementing needs. Subsection temperature control reduces degradation, with a viscosity retention rate of >90%; chloride ion residue <0.1%, and sodium content not detected, with a purity better than two patents.

[0022] 4. Process stability and applicability The slurry method optimizes parameters such as urea dosage and chlorosuccinic acid molar ratio through orthogonal experiment, and can adjust lithium content and viscosity according to demand, with stronger equipment compatibility, no need for strong acid resistant equipment, lower equipment requirements and subsequent maintenance costs. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The process flowchart of the present application. DETAILED DESCRIPTION

[0024] The present application is described below in conjunction with examples, which are used to explain the present application and are not intended to limit the scope of the present application.

[0025] Example 1 The refined cotton is crushed to 60-100 mesh to form cellulose powder, mixed with 70-98% isopropyl alcohol aqueous solution to form slurry, 2200g of 90% isopropyl alcohol, 147g of lithium hydroxide monohydrate are added into a glass reaction kettle and stirred, after complete dissolution, the temperature is controlled at 20°C, then 150g of the slurry of the refined cotton after complete impregnation is added, after stirring for 30min, 4.5g of urea dissolved in isopropyl alcohol is added, N2 is passed, stirring is carried out at 25°C for 90min, 183g of chlorosuccinic acid (60% isopropyl alcohol solution) is weighed, the 60% chlorosuccinic acid isopropyl alcohol solution formed by dissolving 183g of chlorosuccinic acid solid into isopropyl alcohol solution is poured into a constant pressure funnel and slowly dropped into the reaction kettle within 40min, the temperature is controlled at 40°C for etherification for 60min, after the reaction temperature is increased to 75°C for 40min, it is cooled to 30-55°C, hydrochloric acid is used to adjust the pH to neutral, after three times of centrifugation after stepwise filtration washing with 60%, 70% and 80% ethanol respectively, drying and crushing are carried out.

[0026] The detection results are as follows: lithium content 5.07wt%, degree of substitution 1.09, viscosity (1% aqueous solution) 2089cP.

[0027] Example 2 The refined cotton is crushed to 60-100 mesh to form cellulose powder, mixed with 70-98% isopropyl alcohol aqueous solution to form slurry, 2200g of 90% isopropyl alcohol, 147g of lithium hydroxide monohydrate are added into a glass reaction kettle and stirred, after complete dissolution, the temperature is controlled at 20°C, then 150g of the slurry of the refined cotton after complete impregnation is added, after stirring for 30min, 4.5g of urea dissolved in isopropyl alcohol is added, N2 is passed, stirring is carried out at 25°C for 90min, 183g of chlorosuccinic acid (60% isopropyl alcohol solution) is weighed, the 60% chlorosuccinic acid isopropyl alcohol solution formed by dissolving 183g of chlorosuccinic acid solid into isopropyl alcohol solution is poured into a constant pressure funnel and slowly dropped into the reaction kettle within 40min, the temperature is controlled at 40°C for etherification for 60min, after the reaction temperature is increased to 75°C for 40min, it is cooled to 30-55°C, hydrochloric acid is used to adjust the pH to neutral, after three times of centrifugation after stepwise filtration washing with 60%, 70% and 80% ethanol respectively, drying and crushing are carried out.

[0028] The detection results are as follows: lithium content 5.07wt%, degree of substitution 1.09, viscosity (1% aqueous solution) 2089cP.

[0029] Example 3 The refined cotton is crushed to 60-100 mesh to form cellulose powder, mixed with 70-98% isopropyl alcohol aqueous solution to form slurry, 2200g of 90% isopropyl alcohol, 147g of lithium hydroxide monohydrate are added into a glass reaction kettle and stirred, after complete dissolution, the temperature is controlled at 20°C, then 150g of the slurry of the refined cotton after completion of impregnation is added, stirred for 30min, then 4.5g of urea dissolved in isopropyl alcohol is added, N2 is passed, stirred at 25°C for 90min, 192.3g of chlorosuccinic acid (60% isopropyl alcohol solution) is weighed and slowly dropped into the reaction kettle through a constant pressure funnel within 40min, the temperature is controlled at 40°C for etherification for 60min, the reaction temperature is raised to 75°C for reaction for 40min, then cooled to 30-55°C, neutralized with hydrochloric acid, sequentially washed with 60%, 70% and 80% ethanol by gradient filtration, centrifuged, then dried, and crushed.

[0030] The detection results are as follows: lithium content 5.29wt%, degree of substitution 1.19, and viscosity (1% aqueous solution) 2388cP.

[0031] Example 4 The refined cotton is crushed to 60-100 mesh to form cellulose powder, mixed with 70-98% isopropyl alcohol aqueous solution to form slurry, 2200g of 90% isopropyl alcohol, 147g of lithium hydroxide monohydrate are added into a glass reaction kettle and stirred, after complete dissolution, the temperature is controlled at 20°C, then 150g of the slurry of the refined cotton after completion of impregnation is added, stirred for 30min, then 4.5g of urea dissolved in isopropyl alcohol is added, N2 is passed, stirred at 25°C for 90min, 183g of chlorosuccinic acid (60% isopropyl alcohol solution) is weighed and slowly dropped into the reaction kettle through a constant pressure funnel within 40min, the temperature is controlled at 45°C for etherification for 65min, the reaction temperature is raised to 77°C for reaction for 45min, then cooled to 30-55°C, neutralized with hydrochloric acid, sequentially washed with 60%, 70% and 80% ethanol by gradient filtration, centrifuged, then dried, and crushed.

[0032] The detection results are as follows: lithium content 5.29wt%, degree of substitution 1.19, and viscosity (1% aqueous solution) 2388cP.

[0033] Comparative Example 1 The refined cotton is crushed to 60-100 mesh to form cellulose powder, mixed with 70-98% isopropyl alcohol aqueous solution to form slurry, 2200g of 90% isopropyl alcohol, 147g of lithium hydroxide monohydrate are added into a glass reaction kettle and stirred, after complete dissolution, the temperature is controlled at 20°C, then 150g of the slurry of the refined cotton after completion of the impregnation is added, stirred for 30min, then 4.5g of urea dissolved in isopropyl alcohol is added, N2 is passed, stirred at 25°C for 90min, 125g of chloroacetic acid (60% isopropyl alcohol solution) is weighed and poured into a constant pressure funnel and slowly dropped into the reaction kettle within 40min, the temperature is controlled at 40°C for etherification for 60min, the reaction temperature is raised to 75°C for reaction for 40min, then cooled to 30-55°C, neutralized with hydrochloric acid, sequentially washed with 60%, 70%, 80% ethanol by gradient filtration three times, centrifuged, then dried, and crushed.

[0034] The detection results are as follows: lithium content 4.21wt%, degree of substitution 0.79, viscosity (1% aqueous solution) 1753cP.

[0035] Comparative Example 2 The refined cotton is crushed to 60-100 mesh to form cellulose powder, mixed with 70-98% isopropyl alcohol aqueous solution to form slurry, 2200g of 90% isopropyl alcohol, 147g of lithium hydroxide monohydrate are added into a glass reaction kettle and stirred, after complete dissolution, the temperature is controlled at 20°C, then 150g of the slurry of the refined cotton after completion of the impregnation is added, stirred for 30min, then 4.5g of urea dissolved in isopropyl alcohol is added, N2 is passed, stirred at 25°C for 90min, 125g of chloroacetic acid (60% isopropyl alcohol solution) is weighed and poured into a constant pressure funnel and slowly dropped into the reaction kettle within 40min, the temperature is controlled at 40°C for etherification for 60min, the reaction temperature is raised to 75°C for reaction for 40min, then cooled to 30-55°C, neutralized with hydrochloric acid, sequentially washed with 60%, 70%, 80% ethanol by gradient filtration three times, centrifuged, then dried, and crushed.

[0036] The detection results are as follows: lithium content 4.21wt%, degree of substitution 0.79, viscosity (1% aqueous solution) 1753cP.

[0037] Comparative Example 3 The refined cotton is crushed to 60-100 mesh to form cellulose powder, mixed with isopropanol aqueous solution with a mass fraction of 70-98% to form a slurry, 2200 g of isopropanol with a mass fraction of 90% is added into a glass reaction kettle, 147 g of lithium hydroxide monohydrate is mixed and stirred, after complete dissolution, the temperature is controlled at 20°C, then 150 g of the slurry of the refined cotton after complete infiltration is added, after stirring for 30 min, isopropanol solution of undissolved urea is added, N2 is passed, stirring is carried out at 25°C for 90 min, 125 g of chloroacetic acid (60% isopropanol solution) is weighed and poured into a constant pressure funnel and slowly dropped into the reaction kettle within 40 min, the temperature is controlled at 40°C for etherification for 60 min, after the reaction temperature is increased to 75°C for 40 min, it is cooled to 30-55°C, hydrochloric acid is used to adjust the pH to neutral, and the product is washed by gradient filtration with 60%, 70% and 80% ethanol concentration respectively three times, then centrifuged, dried and crushed.

[0038] The detection results are as follows: lithium content 3.22 wt%, degree of substitution 1.06, and viscosity (1% aqueous solution) 1255 cP.

[0039] Comparative Example 4 The refined cotton is crushed to 60-100 mesh to form cellulose powder, mixed with isopropanol aqueous solution with a mass fraction of 70-98% to form a slurry, 2200 g of isopropanol with a mass fraction of 90% is added into a glass reaction kettle, 147 g of lithium hydroxide monohydrate is mixed and stirred, after complete dissolution, the temperature is controlled at 20°C, then 150 g of the slurry of the refined cotton after complete infiltration is added, after stirring for 30 min, isopropanol solution of undissolved urea is added, N2 is passed, stirring is carried out at 25°C for 90 min, 125 g of chloroacetic acid (60% isopropanol solution) is weighed and poured into a constant pressure funnel and slowly dropped into the reaction kettle within 40 min, the temperature is controlled at 40°C for etherification for 60 min, after the reaction temperature is increased to 75°C for 40 min, it is cooled to 30-55°C, hydrochloric acid is used to adjust the pH to neutral, and the product is washed by gradient filtration with 60%, 70% and 80% ethanol concentration respectively three times, then centrifuged, dried and crushed.

[0040] The detection results are as follows: lithium content 3.22 wt%, degree of substitution 1.06, and viscosity (1% aqueous solution) 1255 cP.

[0041] 1. Lithium source substitution scheme: ① Lithium ethoxide substitution: lithium ethoxide can be used to partially or completely replace lithium hydroxide, the dosage ratio is m(lithium ethoxide):m(cellulose)=0.7-0.9:1. Lithium ethoxide has better solubility and reactivity, but the cost is higher, and it is suitable for high-end battery products; ② Composite lithium source: lithium hydroxide and lithium carbonate are compounded (mass ratio 3:1-5:1), lithium carbonate releases lithium ions gradually in the reaction, improving the uniformity of the reaction. This scheme can reduce the severity of the reaction, and is especially suitable for the preparation of high-substitution-degree products; 2. Solvent system alternatives Isopropyl alcohol-tert-butyl alcohol mixed system: when isopropyl alcohol and tert-butyl alcohol are mixed at 75%:25%, the viscosity and degree of substitution of CMC-Li can be significantly improved. This system promotes the uniformity of the alkalization and etherification reactions by reducing the polarity of the reaction medium, reducing side reactions.

[0042] Detection method: The lithium content was tested using inductively coupled plasma optical emission spectrometry (ICP-OES), the degree of substitution was calculated by measuring the lithium content of the product, and the viscosity of a 1% aqueous solution was measured using a Brookfield DV-II + rotational viscometer.

[0043] Table 1 is an integrated experimental table that clearly presents the experimental parameters and results of the examples and comparative examples under different conditions: Table 1. Parameters and performance test data of examples and comparative examples

[0044] Table notes: 1. Common experimental conditions: all experiments were carried out in a glass reaction kettle, the initial temperature was controlled at 20°C, refined cotton was added, N2 protection was used, and after the reaction, centrifugation, drying, and crushing were carried out.

[0045] 2. Variable comparison: Urea dosage: 4.5g for examples 1, 3, and 4, 6g for example 2, and not used for comparative examples 1 and 3.

[0046] Chlorinated reagent: chlorosuccinic acid was used for examples 1-4, and chloroacetic acid was used for comparative examples 2-3, with different samples.

[0047] Temperature and time: the etherification temperature and subsequent reaction temperature were adjusted for example 4, the etherification temperature was adjusted for comparative example 4 without subsequent temperature increase, and the temperature was controlled consistently for the remaining examples.

[0048] 3. Result analysis: the addition of urea, the use of chlorosuccinic acid, and the control of appropriate reaction temperature and time can significantly improve the lithium content, degree of substitution, and solution viscosity.

[0049] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing high-lithium-content carboxymethyl cellulose lithium, characterized in that, Includes the following steps: (1) Raw material pretreatment: The refined cotton is pulverized to 60-100 mesh to form cellulose powder, which is then mixed with an isopropanol aqueous solution with a mass fraction of 70-98% to form a slurry; the lithium source is dissolved in an isopropanol aqueous solution with a mass fraction of 70-95% to prepare an alkaline solution with a concentration of 3-10%, which is denoted as solution 1; chlorosuccinic acid is dissolved in an isopropanol aqueous solution to prepare a solution with a mass concentration of 50-70%, which is denoted as solution 2; (2) Alkalization reaction: Add urea (3-10% of the cellulose mass) and the slurry described in step (1) to solution 1, and stir the reaction at 15-40℃ for 50-120 minutes under nitrogen protection. (3) Etherification reaction: Slowly add solution 2 to the system after the alkalization reaction, stir evenly and carry out the initial reaction, then raise the temperature to 70-85℃ at a rate of 1-2℃ / min and react for 30-60 minutes; (4) Post-treatment: The reaction solution is cooled to 30-55℃, neutralized with dilute hydrochloric acid to pH 6.5-8.5, centrifuged, and washed stepwise with ethanol of increasing concentration. After centrifugation, it is vacuum dried at 80-100℃, pulverized and sieved to obtain a white powdered lithium carboxymethyl cellulose product.

2. The method for preparing high-lithium-content carboxymethyl cellulose lithium according to claim 1, characterized in that, The lithium source is at least one of lithium hydroxide, lithium ethanol, and lithium carbonate.

3. The method for preparing high-lithium-content carboxymethyl cellulose lithium according to claim 1, characterized in that, The alkalization reaction in step (2) is carried out at 25°C.

4. The method for preparing high-lithium-content carboxymethyl cellulose lithium according to claim 1, characterized in that, In the etherification reaction in step (3), the temperature is increased to 75°C at a rate of 1-2°C / min.

5. The method for preparing high-lithium-content carboxymethyl cellulose lithium according to claim 1, characterized in that, The refined cotton in step (1) has an α-cellulose content greater than 95%.

6. A high-lithium-content carboxymethyl cellulose lithium, characterized in that, The high-lithium-content lithium carboxymethyl cellulose is prepared by any one of the preparation methods of claims 1 to 5, and has a purity ≥ 99.5%, a lithium content of 5.0-5.3 wt%, a degree of substitution of 1.09-1.22, and a viscosity of ≥ 2000 cP in 1% aqueous solution.

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