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WO2024197618A1 - 一种电化学脱嵌法盐湖提锂电极及其制备方法和应用 - Google Patents

一种电化学脱嵌法盐湖提锂电极及其制备方法和应用 Download PDF

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Publication number
WO2024197618A1
WO2024197618A1 PCT/CN2023/084574 CN2023084574W WO2024197618A1 WO 2024197618 A1 WO2024197618 A1 WO 2024197618A1 CN 2023084574 W CN2023084574 W CN 2023084574W WO 2024197618 A1 WO2024197618 A1 WO 2024197618A1
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preparation
electrode
ion sieve
epoxy
lithium
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PCT/CN2023/084574
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English (en)
French (fr)
Inventor
李爱霞
余海军
谢英豪
李长东
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广东邦普循环科技有限公司
湖南邦普循环科技有限公司
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Application filed by 广东邦普循环科技有限公司, 湖南邦普循环科技有限公司 filed Critical 广东邦普循环科技有限公司
Priority to PCT/CN2023/084574 priority Critical patent/WO2024197618A1/zh
Priority to CN202380009633.6A priority patent/CN116829767A/zh
Publication of WO2024197618A1 publication Critical patent/WO2024197618A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/18—Alkaline earth metal compounds or magnesium compounds
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • the present application belongs to the field of lithium extraction from salt lakes, for example, an electrochemical deintercalation method for lithium extraction from salt lakes electrode and its preparation method and application.
  • the developed salt lake lithium extraction methods include adsorption method, solution extraction method, electrodialysis method and electrochemical deintercalation method.
  • the electrochemical deintercalation method uses LiFePO 4 /FePO 4 electrodes as anodes/cathode, and drives lithium ions to embed into FePO 4 electrode materials through an external circuit to achieve selective extraction of lithium.
  • the mass transfer effect of lithium ions in the electrode is a key factor affecting the rate of lithium extraction by the electrochemical deintercalation method.
  • the electrodes are blended and modified by introducing hydrophilic inorganic nano-oxides and binders to improve the hydrophilicity of the electrodes to the solution and reduce the concentration difference expansion during the lithium extraction process.
  • the amount of hydrophilic inorganic nano-oxides and binders is difficult to control. Adding too little will not significantly improve the hydrophilicity of the electrode and the mass transfer effect of the solution. Adding too much will result in a low proportion of electrode active substances, resulting in a decrease in the amount of lithium extracted per unit area.
  • CN113293290A discloses an electrode material for lithium extraction from salt lakes, a preparation method and an application thereof, which improves the selectivity and hydrophilicity of the electrode active material by coating the surface of the electrode active material for lithium extraction with a graphene oxide/manganese ion sieve composite.
  • the modified electrode active material is used as a raw material, and in the process of electrode preparation, an inorganic nano-oxide is introduced to modify the binder by blending, and a porous electrode is prepared by adding a pore-forming agent, which further improves the affinity of the electrode to the solution, and the presence of the porous structure strengthens the solution in the Mass transfer inside the electrode reduces the concentration difference expansion in the lithium extraction process and improves the electrochemical performance of the electrode.
  • CN113265538A discloses a method for preparing a highly conductive porous electrode for lithium extraction from salt lakes, which includes the steps of using inorganic nanoparticles and polar hydrophilic macromolecular organic matter to blend and modify the binder in the electrode preparation process to improve the hydrophilicity of the binder.
  • inorganic salt pore-forming agents are added to form holes of different sizes in the electrode during the drying process, thereby improving the mass transfer effect of the solution inside the electrode plate.
  • the prepared electrode material is subjected to surface chemical modification in a conductive polymer monomer solution.
  • the amount of hydrophilic inorganic nano-oxide and binder used in the above scheme is difficult to control. Adding too little will result in little improvement in the hydrophilicity of the electrode and the mass transfer effect of the solution. Adding too much will result in a too low proportion of electrode active substances, resulting in a decrease in lithium extraction per unit area.
  • the present application provides an electrode for extracting lithium from salt lakes by an electrochemical deintercalation method, and a preparation method and application thereof.
  • the present application aims to improve the hydrophilicity of the mass transfer channels and the mass transfer effect of the solution by locally modifying the pores of the ion sieve to be superoleophobic and superhydrophilic, and in addition, successfully avoids a decrease in the proportion of active substances in the electrode and a decrease in the adsorption capacity due to excessive addition of hydrophilic substances.
  • an embodiment of the present application provides a method for preparing a lithium-extraction electrode from a salt lake by an electrochemical deintercalation method, the preparation method comprising the following steps:
  • the embodiment of the present application improves the hydrophilicity of the pores and thus enhances the mass transfer of the solution in the pores by locally modifying the pores of the ion sieve to be superoleophobic and superhydrophilic.
  • the preparation method avoids the decrease in the proportion of electrode active materials and the amount of lithium extracted per unit area due to excessive addition of hydrophilic substances.
  • the silicon source in step (1) comprises tetraethyl orthosilicate.
  • the silane coupling agent includes KH-560.
  • the solvent comprises anhydrous ethanol.
  • the mass ratio of the silicon source, the silane coupling agent and the solvent is (1.5-2.5):1:(4-6), for example: 1.5:1:4, 1.8:1:5, 2:1:5, 2.2:1:5.2 or 2.5:1:6, etc.
  • the acid solution in step (1) comprises nitric acid.
  • the mass ratio of the mixed solution to the acid solution is (3.2-3.5):1, for example: 3.2:1, 3.3:1, 3.4:1 or 3.5:1, etc.
  • the ultrasound duration is 1.5 to 3 hours, for example, 1.5 hours, 1.8 hours, 2 hours, 2.5 hours or 3 hours.
  • the freeze-drying process comprises first freezing at -4°C for 12 hours and then freezing at -40°C for 24 hours.
  • the adhesive in step (2) comprises epoxy resin.
  • the ion sieve includes any one of an iron phosphate ion sieve or a lithium titanate ion sieve or a combination of both.
  • the mass ratio of the epoxy-modified silica powder to the ion sieve is (0.2 ⁇ 1):100, for example: 0.2:100, 0.4:100, 0.6:100, 0.8:100 or 1:100, etc.
  • the epoxy-modified silica described in the examples of the present application has good hydrophilic and oleophobic properties.
  • the epoxy-modified silica hydrophilic and oleophobic film is formed in the pores of the ion sieve, the mass transfer effect of the solution inside is improved.
  • This preparation method successfully avoids the reduction of the proportion of electrode active materials and the amount of lithium extracted per unit area due to excessive addition of hydrophilic substances.
  • the mass ratio of the adhesive to the epoxy-modified silica powder is (0.02-0.1):100, for example: 0.02:100, 0.04:100, 0.06:100, 0.08:100 or 0.1:100, etc.
  • epoxy-modified silica will form a hydrophilic and oleophobic film in the pores of the ion sieve at high temperatures.
  • This local modification avoids the excessive addition of hydrophilic substances, which leads to a decrease in the proportion of electrode active substances and the amount of lithium extracted per unit area, and improves the mass transfer effect of the solution.
  • the grinding speed in step (2) is 100-200 rpm, for example, 100 rpm, 120 rpm, 150 rpm, 180 rpm or 200 rpm.
  • the epoxy-modified silica and epoxy resin when the ball mill is running at high speed, the epoxy-modified silica and epoxy resin will enter the pores of the ion sieve; in addition, by controlling the rotation speed of the high-speed ball mill, the amount of epoxy-modified silica and epoxy resin entering the pores of the positive electrode material can be controlled.
  • the separation comprises air flow separation.
  • the air flow separation has an air flow velocity of 10 to 15 m/s, for example, 10 m/s, 11 m/s, 12 m/s, 13 m/s, 14 m/s or 15 m/s.
  • the uniformly mixed particles are sent to an air flow separation device, and the separation of large and small particles is achieved by controlling the wind speed and utilizing the different centrifugal forces exerted on the large and small particles.
  • the binder in step (3) includes polyvinylidene fluoride.
  • the conductive agent includes acetylene black.
  • the solvent comprises N-methylpyrrolidone.
  • the mass ratio of the locally modified ion sieve, binder and conductive agent is (6-8):1:(1.5-2.5), for example: 6:1:1.5, 6.5:1:1.8, 7:1:2, 7.5:1:2.2 or 8:1:2.5, etc.
  • the coating area in step (3) is 1500-1800 cm 2 , for example, 1500 cm 2 , 1550 cm 2 , 1600 cm 2 , 1700 cm 2 , 1750 cm 2 or 1800 cm 2 .
  • the coating density is 70-90 mg/cm 2 , for example, 70 mg/cm 2 , 75 mg/cm 2 , 80 mg/cm 2 , 85 mg/cm 2 or 90 mg/cm 2 .
  • an embodiment of the present application provides an electrode for extracting lithium from salt lakes using an electrochemical deintercalation method, wherein the electrode for extracting lithium from salt lakes using an electrochemical deintercalation method is prepared by the method described in the first aspect.
  • the present application aims to improve the hydrophilicity of the mass transfer pores and the mass transfer function of the solution by locally modifying the pores of the ion sieve to be superoleophobic and superhydrophilic; in addition, the present application successfully avoids the decrease in the proportion of electrode active substances and the decrease in adsorption capacity due to excessive addition of hydrophilic substances.
  • the saturated adsorption capacity of the salt lake lithium extraction electrode prepared by the electrochemical deintercalation method described in the present application can reach more than 32.1 mg/g, and the time required for saturated adsorption can reach less than 14.9 h.
  • This embodiment provides an electrochemical deintercalation method for extracting lithium from salt lakes.
  • the preparation method of the electrochemical deintercalation method for extracting lithium from salt lakes is as follows:
  • TEOS, silane coupling agent KH-560 and anhydrous ethanol are mixed in a mass ratio of 2:1:5 and stirred for 10 minutes to obtain a mixed solution A; 0.21% (volume fraction) dilute nitric acid is added dropwise into the mixed solution A and stirred for hydrolysis for 2 hours to obtain a sol (wherein the mass ratio of the mixed solution A to the nitric acid is 3.4:1); after ultrasonic treatment for 2 hours, the sol is aged at room temperature for 3 to 4 weeks to obtain an epoxy-modified silica sol; and finally, the sol is placed in a -4°C refrigerator for 12 hours, and then placed in a -40°C freeze dryer for 24 hours to obtain an epoxy-modified silica powder;
  • This embodiment provides a salt lake lithium extraction electrode using an electrochemical deintercalation method.
  • the preparation method of lithium extraction electrode is as follows:
  • Tetraethyl orthosilicate, silane coupling agent KH-560 and anhydrous ethanol are mixed and stirred at a mass ratio of 2.2:1:5.2 for 10 minutes to obtain a mixed solution A; 0.21% (volume fraction) dilute nitric acid is added dropwise into the mixed solution A and stirred and hydrolyzed for 2 hours to obtain a sol (wherein the mass ratio of the mixed solution A to the nitric acid is 3.5:1); after ultrasonic treatment for 2 hours, the mixture is placed at room temperature for aging for 3 to 4 weeks to obtain an epoxy-modified silica sol; and finally, the mixture is placed in a -4°C refrigerator for 12 hours, and then placed in a -40°C freeze dryer for 24 hours to obtain an epoxy-modified silica powder;
  • Example 1 The only difference between this comparative example and Example 1 is that the ion sieve is not modified, and the other conditions and parameters are exactly the same as those in Example 1, namely:
  • the iron phosphate ion sieve, PVDF and acetylene black were weighed in a mass ratio of 7:1:2, and N-methylpyrrolidone (NMP) was added after being fully mixed, and the mixture was stirred in a vacuum for 6 hours to obtain an electrode slurry; the slurry was coated on a titanium mesh by a doctor blade method, and finally dried in a vacuum drying oven at 80°C for 12 hours.
  • the slurry coating area was 1680 cm2 , and the coating density was 80 mg/ cm2 , thereby obtaining the salt lake lithium extraction electrode by the electrochemical deintercalation method.
  • Comparative Example 2 The difference between Comparative Example 2 and Comparative Example 1 is that in step (2), 30% of the total mass of hydrophilic nano-silicon dioxide is additionally added.
  • the iron phosphate electrode prepared in Example 1-6 and Comparative Example 1-2 was placed as the cathode in a cathode chamber containing 15 g/L LiCl solution, and the lithium iron phosphate electrode was placed as the anode in an anode chamber containing 30 g/L NaCl solution.
  • the lithium insertion/de-lithiation process was performed under the conditions of constant current and then constant voltage until the current was less than 2 A/m 2 .
  • the test results are shown in Table 1:
  • the saturated adsorption capacity of the electrochemical deintercalation method salt lake lithium extraction electrode prepared by the method described in the present application can reach more than 32.1 mg/g, and the time required for saturated adsorption can reach less than 14.9 h.
  • Example 1 By comparing Example 1 and Examples 3-4, it can be seen that as the speed of the ball mill mixer becomes faster and faster, more and more epoxy-modified silica and epoxy resin adhesive are embedded in the pores of the ion sieve, and the hydrophilic and superoleophobic effects in the pores become better and better, so that the solution can flow freely and quickly in the electrode pores without hindrance (the solution diffusion resistance is small), thereby improving the mass transfer effect of the solution and increasing the adsorption capacity of the electrode for lithium ions.
  • Example 1 By comparing Example 1 with Comparative Example 1, it can be seen that the present application improves the hydrophilicity of the pores and thus improves the mass transfer of the solution in the pores by locally modifying the pores of the ion sieve to be superoleophobic and superhydrophilic, thereby significantly shortening the time required for saturated adsorption.
  • Example 1 By comparing Example 1 and Comparative Example 2, it can be seen that the epoxy-modified silica described in the present application has good hydrophilic and oleophobic properties.
  • the epoxy-modified silica hydrophilic and oleophobic film is formed in the pores of the ion sieve, the mass transfer effect of the solution inside it is improved.
  • This preparation method successfully avoids the reduction of the proportion of electrode active materials and the amount of lithium extracted per unit area due to excessive addition of hydrophilic substances.

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Abstract

本申请提供了一种电化学脱嵌法盐湖提锂电极及其制备方法和应用，所述制备方法包括以下步骤：(1)将硅源、硅烷偶联剂和溶剂混合得到混合溶液，向混合溶液中加入酸得到溶胶，经超声、老化后得到环氧改性硅溶胶，经冻干处理得到环氧改性二氧化硅；(2)将磷酸铁离子筛、环氧改性二氧化硅和粘合剂混合，研磨后分离得到局部改性的磷酸铁离子筛；(3)将局部改性的磷酸铁离子筛、粘结剂和导电剂与溶剂混合得到电极浆料，将电极浆料涂覆在钛网表面得到所述电化学脱嵌法盐湖提锂电极，本申请通过对磷酸铁离子筛的孔隙进行超疏油超亲水局部改性，旨在提高传质孔道的亲水性，提高溶液的传质作用。

Description

一种电化学脱嵌法盐湖提锂电极及其制备方法和应用 技术领域
本申请属于盐湖提锂领域，例如一种电化学脱嵌法盐湖提锂电极及其制备方法和应用。
背景技术
几年来，受到国家政策的扶持，新能源汽车行业迅猛发展，对锂的需求量与日俱增，提锂技术受到人们越来越多的重视。我国是锂消耗大国之一，同时锂资源也是我国产业发展的重要战略资源。我国的锂资源主要分布在盐湖卤水中，所以开发合适的提锂技术具有重大经济价值和战略意义。目前，已开发的盐湖提锂方法有吸附法、溶液萃取法、电渗析法和电化学脱嵌法等。
电化学脱嵌法即采用LiFePO4/FePO4电极作为阳极/阴极，通过外电路驱动锂离子嵌入FePO4电极材料中，以实现锂的选择性提取。锂离子在电极中的传质效果是影响电化学脱嵌法提锂速率的关键因素，一般会通过引入亲水性无机纳米氧化物和粘结剂对电极进行共混改性，改善电极对溶液的亲水性，降低提锂过程的浓差扩大。亲水性无机纳米氧化物和粘合剂的量不好控制，加入过少会使得电极亲水性能和溶液的传质作用提升不明显，加入量过多导致电极活性物质比例过低，导致单位面积提锂量下降。
CN113293290A公开了一种盐湖提锂用电极材料及其制备方法和应用，其通过在提锂用电极活性材料表面包覆氧化石墨烯/锰系离子筛复合物，提高了电极活性材料的选择性和亲水性。以该改性电极活性材料为原料，在电极制备过程中，引入无机纳米氧化物对粘接剂进行共混改性，通过添加造孔剂制备多孔电极，进一步改善了电极对溶液的亲和性，并且多孔结构的存在强化了溶液在 电极内部传质，降低了提锂过程的浓差扩大，提高了电极的电化学性能。
CN113265538A公开了一种盐湖提锂用高导电性多孔电极的制备方法，包括通过采用无机纳米颗粒和极性亲水高分子有机物，对电极制备过程的粘结剂进行共混改性，以提高粘接剂的亲水性。在电极浆料制备过程中，通过添加无机盐造孔剂，使电极在烘干过程中形成大小不一的孔洞，提高溶液在电极板内部的传质效果。最后，将制备好的电极材料在导电聚合物单体溶液中进行表面化学改性。
上述方案使用的亲水性无机纳米氧化物和粘合剂的量不好控制，加入过少会使得电极亲水性能和溶液的传质作用提升不明显，加入量过多导致电极活性物质比例过低，导致单位面积提锂量下降。
发明内容
以下是对本文详细描述的主题的概述。本概述并非是为了限制权利要求的保护范围。
本申请提供一种电化学脱嵌法盐湖提锂电极及其制备方法和应用，本申请通过对离子筛的孔隙进行超疏油超亲水局部改性，旨在提高传质孔道的亲水性，提高溶液的传质作用；此外，成功避免了因亲水物质加入过多导致电极活性物质比例下降和吸附容量的下降。
为达到此申请目的，本申请采用以下技术方案：
第一方面，本申请实施例提供了一种电化学脱嵌法盐湖提锂电极的制备方法，所述制备方法包括以下步骤：
(1)将硅源、硅烷偶联剂和溶剂混合得到混合溶液，向混合溶液中加入酸溶液得到溶胶，经超声、老化后得到环氧改性硅溶胶，经冻干处理得到环氧改性二氧化硅粉末；
(2)将离子筛、环氧改性二氧化硅粉末和粘合剂混合，研磨后分离得到局部改性的离子筛；
(3)将局部改性的离子筛、粘结剂和导电剂与溶剂混合得到电极浆料，将所述电极浆料涂覆在钛网表面得到所述电化学脱嵌法盐湖提锂电极。
本申请实施例通过对离子筛的孔隙进行超疏油超亲水局部改性，改善了孔道的亲水性进而提高了溶液在孔道中的传质作用，该制备方法避免了亲水性物质加入过多导致电极活性物质比例和单位面积提锂量下降。
在一个实施例中，步骤(1)所述硅源包括正硅酸乙酯。
在一个实施例中，所述硅烷偶联剂包括KH-560。
在一个实施例中，所述溶剂包括无水乙醇。
在一个实施例中，所述硅源、硅烷偶联剂和溶剂的质量比为(1.5～2.5):1:(4～6)，例如：1.5:1:4、1.8:1:5、2:1:5、2.2:1:5.2或2.5:1:6等。
在一个实施例中，步骤(1)所述酸溶液包括硝酸。
在一个实施例中，所述混合溶液和酸溶液的质量比为(3.2～3.5):1，例如：3.2:1、3.3:1、3.4:1或3.5:1等。
在一个实施例中，所述超声的时间为1.5～3h，例如：1.5h、1.8h、2h、2.5h或3h等。
在一个实施例中，所述冻干处理包括先在-4℃下12h，后在-40℃冷冻干燥下24h。
在一个实施例中，步骤(2)所述粘合剂包括环氧树脂。
在一个实施例中，所述离子筛包括磷酸铁离子筛或钛酸锂离子筛中的任意一种或两种的组合。
在一个实施例中，所述环氧改性二氧化硅粉末和所述离子筛的质量比为 (0.2～1):100，例如：0.2:100、0.4:100、0.6:100、0.8:100或1:100等。
本申请实施例所述环氧改性二氧化硅具有良好的亲水疏油性能，当离子筛孔隙内形成环氧改性二氧化硅亲水疏油膜，提高溶液在其内部的传质效果。这种制备方法成功避免了亲水性物质加入过多而导致电极活性物质比例和单位面积提锂量下降。
在一个实施例中，所述粘合剂和所述环氧改性二氧化硅粉末的质量比为(0.02～0.1):100，例如：0.02:100、0.04:100、0.06:100、0.08:100或0.1:100等。
在粘合剂的作用下，环氧改性二氧化硅在高温情况下会在离子筛孔隙内形成亲水疏油膜，这种局部改性避免了亲水性物质加入过多而导致电极活性物质比例和单位面积提锂量下降，并且提高了溶液的传质作用。
在一个实施例中，步骤(2)所述研磨的速度为100～200rpm，例如：100rpm、120rpm、150rpm、180rpm或200rpm等。
本申请实施例在球磨搅拌机的高速运转下，环氧改性二氧化硅和环氧树脂会进入离子筛孔隙内；此外，通过控制高速球磨搅拌机的简体转速，可以调控环氧改性二氧化硅和环氧树脂进入正极材料孔隙内的量。
在一个实施例中，所述分离包括气流分离。
在一个实施例中，所述气流分离的气流速度为10～15m/s，例如：10m/s、11m/s、12m/s、13m/s、14m/s或15m/s等。
本申请实施例将混合均匀后的颗粒送入气流分离装置中，通过控制风速，利用大小颗粒受到的离心力不同来实现大小颗粒的分离。
在一个实施例中，步骤(3)所述粘结剂包括聚偏氟乙烯。
在一个实施例中，所述导电剂包括乙炔黑。
在一个实施例中，所述溶剂包括N-甲基吡咯烷酮。
在一个实施例中，所述局部改性的离子筛、粘结剂和导电剂的质量比为(6～8):1:(1.5～2.5)，例如：6:1:1.5、6.5:1:1.8、7:1:2、7.5:1:2.2或8:1:2.5等。
在一个实施例中，步骤(3)所述涂覆的面积为1500～1800cm2，例如：1500cm2、1550cm2、1600cm2、1700cm2、1750cm2或1800cm2等。
在一个实施例中，所述涂覆的密度为70～90mg/cm2，例如：70mg/cm2、75mg/cm2、80mg/cm2、85mg/cm2或90mg/cm2等。
第二方面，本申请实施例提供了一种电化学脱嵌法盐湖提锂电极，所述电化学脱嵌法盐湖提锂电极通过如第一方面所述方法制得。
相对于相关技术，本申请具有以下有益效果：
(1)本申请通过对离子筛的孔隙进行超疏油超亲水局部改性，旨在提高传质孔道的亲水性，提高溶液的传质作用；此外，成功避免了因亲水物质加入过多导致电极活性物质比例下降和吸附容量的下降。
(2)在球磨搅拌机的高速运转下，环氧改性二氧化硅和环氧树脂会进入大颗粒离子筛孔隙内；此外，通过控制高速球磨搅拌机的简体转速，可以调控环氧改性二氧化硅和环氧树脂进入正极材料孔隙内的量。当简体转速较低时，大部分环氧改性二氧化硅和环氧树脂聚集在颗粒表面，难以进入颗粒表面的裂纹和缺陷内，随后，停留在颗粒表面的环氧改性二氧化硅和环氧树脂会被气流分离装置分离出去。
(3)本申请所述方法制得电化学脱嵌法盐湖提锂电极的饱和吸附量可达32.1mg/g以上，饱和吸附所需时间可达14.9h以下。
在阅读并理解了详细描述后，可以明白其他方面。
具体实施方式
下面通过具体实施方式来进一步说明本申请的技术方案。本领域技术人员 应该明了，所述实施例仅仅是帮助理解本申请，不应视为对本申请的具体限制。
实施例1
本实施例提供了一种电化学脱嵌法盐湖提锂电极，所述电化学脱嵌法盐湖提锂电极的制备方法如下：
(1)按质量比2:1:5将正硅酸乙酯，硅烷偶联剂KH-560和无水乙醇混合搅拌10min得到混合液A；往混合液A中逐滴滴入0.21％(体积分数)稀硝酸搅拌水解2h得到溶胶(其中混合液A和硝酸的质量比为3.4:1)；超声处理2h后置于室温中老化3～4周，制得环氧改性硅溶胶；最后放入-4℃冰箱中12h，随后置于-40℃冷冻干燥机中24h得到环氧改性二氧化硅粉末；
(2)取磷酸铁离子筛，环氧改性二氧化硅，环氧树脂在高速球磨搅拌机中充分球磨，球磨1h后，将物料送入气流分离装置中，将磷酸铁离子筛和未嵌入到正极材料孔隙中的环氧改性二氧化硅分离开来。最后，将磷酸铁离子筛置于100℃烘箱中干燥，即可得到局部改性的磷酸铁离子筛，其中，所述环氧改性二氧化硅相对于正极材料的质量比为0.5％；球磨搅拌机的简体速度为150rpm；气流分离装置中气流速度为12m/s；环氧树脂粘合剂相对于环氧改性二氧化硅质量比为0.05％；
(3)按质量比7:1:2分别称取局部改性的磷酸铁离子筛、PVDF和乙炔黑，充分混合后加入N-甲基吡咯烷酮(NMP)真空搅拌6h，得到电极浆料；采用刮涂法将浆料涂覆在钛网上，最后在80℃真空干燥箱中烘12h，所述浆料涂覆面积为1680cm2，涂覆密度为80mg/cm2，得到所述电化学脱嵌法盐湖提锂电极。
实施例2
本实施例提供了一种电化学脱嵌法盐湖提锂电极，所述电化学脱嵌法盐湖 提锂电极的制备方法如下：
(1)按质量比2.2:1:5.2将正硅酸乙酯，硅烷偶联剂KH-560和无水乙醇混合搅拌10min得到混合液A；往混合液A中逐滴滴入0.21％(体积分数)稀硝酸搅拌水解2h得到溶胶(其中混合液A和硝酸的质量比为3.5:1)；超声处理2h后置于室温中老化3～4周，制得环氧改性硅溶胶；最后放入-4℃冰箱中12h，随后置于-40℃冷冻干燥机中24h得到环氧改性二氧化硅粉末；
(2)取磷酸铁离子筛，环氧改性二氧化硅，环氧树脂在高速球磨搅拌机中充分球磨，球磨1h后，将物料送入气流分离装置中，将磷酸铁离子筛和未嵌入到正极材料孔隙中的环氧改性二氧化硅分离开来。最后，将磷酸铁离子筛置于100℃烘箱中干燥，即可得到局部改性的磷酸铁离子筛，其中，所述环氧改性二氧化硅相对于正极材料的质量比为0.6％；球磨搅拌机的简体速度为100rpm；气流分离装置中气流速度为14m/s；环氧树脂粘合剂相对于环氧改性二氧化硅质量比为0.06％；
(3)按质量比7:1:2分别称取局部改性的磷酸铁离子筛、PVDF和乙炔黑，充分混合后加入N-甲基吡咯烷酮(NMP)真空搅拌6h，得到电极浆料；采用刮涂法将浆料涂覆在钛网上，最后在80℃真空干燥箱中烘12h，所述浆料涂覆面积为1680cm2，涂覆密度为80mg/cm2，得到所述电化学脱嵌法盐湖提锂电极。
实施例3
本实施例与实施例1区别仅在于，球磨搅拌机的简体速度为50rpm，气流分离装置的气流速度为15m/s，其他条件与参数与实施例1完全相同。
实施例4
本实施例与实施例1区别仅在于，球磨搅拌机的简体速度为200rpm，气流 分离装置的气流速度为10m/s，其他条件与参数与实施例1完全相同。
对比例1
本对比例与实施例1区别仅在于，不对离子筛进行改性处理，其他条件与参数与实施例1完全相同，即：
按质量比7:1:2分别称取磷酸铁离子筛、PVDF和乙炔黑，充分混合后加入N-甲基吡咯烷酮(NMP)真空搅拌6h，得到电极浆料；采用刮涂法将浆料涂覆在钛网上，最后在80℃真空干燥箱中烘12h，所述浆料涂覆面积为1680cm2，涂覆密度为80mg/cm2，得到所述电化学脱嵌法盐湖提锂电极。
对比例2
本对比例2与对比例1的区别在于，步骤(2)中额外加入占总质量30％的亲水性纳米二氧化硅。
性能测试：
以实施例1-6和对比例1-2制备好的磷酸铁电极作为阴极置于含有15g/L LiCl溶液的阴极室，磷酸铁锂电极为阳极置于含有30g/L NaCl溶液的阳极室。采用先恒流再恒压的工艺条件进行嵌锂/脱锂，直至电流小于2A/m2，测试结果如表1所示：
表1

由表1可以看出，由实施例1-2可得，本申请所述方法制得电化学脱嵌法盐湖提锂电极的饱和吸附量可达32.1mg/g以上，饱和吸附所需时间可达14.9h以下。
由实施例1和实施例3-4对比可得，随着球磨搅拌机的简体速度越来越快，嵌入到离子筛孔隙中的环氧改性二氧化硅和环氧树脂粘合剂越来越多，孔隙内的亲水超疏油效果越来越好，使得溶液可以快速在电极孔道中自由流动不受阻碍(溶液扩散阻力小)，提高了溶液的传质效果，并且提高了电极对锂离子的吸附容量。
由实施例1和对比例1对比可得，本申请通过对离子筛的孔隙进行超疏油超亲水局部改性，改善了孔道的亲水性进而提高了溶液在孔道中的传质作用，明显缩短饱和吸附所需时间。
由实施例1和对比例2对比可得，本申请所述环氧改性二氧化硅具有良好的亲水疏油性能，当离子筛孔隙内形成环氧改性二氧化硅亲水疏油膜，提高溶液在其内部的传质效果。这种制备方法成功避免了亲水性物质加入过多而导致电极活性物质比例和单位面积提锂量下降。

Claims (17)

  1. 一种电化学脱嵌法盐湖提锂电极的制备方法，所述制备方法包括以下步骤：
    (1)将硅源、硅烷偶联剂和溶剂混合得到混合溶液，向混合溶液中加入酸溶液得到溶胶，经超声、老化后得到环氧改性硅溶胶，经冻干处理得到环氧改性二氧化硅粉末；
    (2)将离子筛、环氧改性二氧化硅粉末和粘合剂混合，研磨后分离得到局部改性的离子筛；
    (3)将局部改性的离子筛、粘结剂和导电剂与溶剂混合得到电极浆料，将所述电极浆料涂覆在钛网表面得到所述电化学脱嵌法盐湖提锂电极。
  2. 如权利要求1所述的制备方法，其中，步骤(1)所述硅源包括正硅酸乙酯。
  3. 如权利要求1或2所述的制备方法，其中，所述硅烷偶联剂包括KH-560。
  4. 如权利要求1-3任一项所述的制备方法，其中，所述溶剂包括无水乙醇。
  5. 如权利要求1-4任一项所述的制备方法，其中，所述硅源、硅烷偶联剂和溶剂的质量比为(1.5～2.5):1:(4～6)。
  6. 如权利要求1-5任一项所述的制备方法，其中，步骤(1)所述酸溶液包括硝酸。
  7. 如权利要求1-6任一项所述的制备方法，其中，所述混合溶液和酸溶液的质量比为(3.2～3.5):1。
  8. 如权利要求1-7任一项所述的制备方法，其中，步骤(1)所述超声的时间为1.5～3h。
  9. 如权利要求1-8任一项所述的制备方法，其中，所述冻干处理包括先在-4℃下12h，后在-40℃冷冻干燥下24h。
  10. 如权利要求1-9任一项所述的制备方法，其中，步骤(2)所述粘合剂包括环氧树脂。
  11. 如权利要求1-10任一项所述的制备方法，其中，所述离子筛包括磷酸铁离子筛或钛酸锂离子筛中的任意一种或两种的组合。
  12. 如权利要求1-11任一项所述的制备方法，其中，步骤(2)所述环氧改性二氧化硅粉末和所述离子筛的质量比为(0.2～1):100。
  13. 如权利要求1-12任一项所述的制备方法，其中，所述粘合剂和所述环氧改性二氧化硅粉末的质量比为(0.02～0.1):100。
  14. 如权利要求1-13任一项所述的制备方法，其中，步骤(2)所述研磨的速度为100～200rpm；
    可选地，所述分离包括气流分离；
    可选地，所述气流分离的气流速度为10～15m/s。
  15. 如权利要求1-14任一项所述的制备方法，其中，步骤(3)所述粘结剂包括聚偏氟乙烯；
    可选地，所述导电剂包括乙炔黑；
    可选地，所述溶剂包括N-甲基吡咯烷酮；
    可选地，所述局部改性的离子筛、粘结剂和导电剂的质量比为(6～8):1:(1.5～2.5)。
  16. 如权利要求1-15任一项所述的制备方法，其中，步骤(3)所述涂覆的面积为1500～1800cm2；
    可选地，所述涂覆的密度为70～90mg/cm2。
  17. 一种电化学脱嵌法盐湖提锂电极，所述电化学脱嵌法盐湖提锂电极通过如权利要求1-16任一项所述方法制得。
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