WO2024259636A1 - 一种电化学脱嵌盐湖提锂的方法 - Google Patents

一种电化学脱嵌盐湖提锂的方法 Download PDF

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WO2024259636A1
WO2024259636A1 PCT/CN2023/101728 CN2023101728W WO2024259636A1 WO 2024259636 A1 WO2024259636 A1 WO 2024259636A1 CN 2023101728 W CN2023101728 W CN 2023101728W WO 2024259636 A1 WO2024259636 A1 WO 2024259636A1
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lithium
electrode
cathode
reaction
constant voltage
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French (fr)
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李爱霞
谢英豪
余海军
李长东
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Hunan Brunp Recycling Technology Co Ltd
Guangdong Brunp Recycling Technology Co Ltd
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Hunan Brunp Recycling Technology Co Ltd
Guangdong Brunp Recycling Technology Co Ltd
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Priority to CN202380009669.4A priority Critical patent/CN117015516B/zh
Priority to PCT/CN2023/101728 priority patent/WO2024259636A1/zh
Publication of WO2024259636A1 publication Critical patent/WO2024259636A1/zh
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
    • C01D15/00—Lithium compounds
    • C01D15/04—Halides
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B26/00—Obtaining alkali, alkaline earth metals or magnesium
    • C22B26/10—Obtaining alkali metals
    • C22B26/12—Obtaining lithium
    • 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
    • C25B1/14—Alkali metal compounds

Definitions

  • the embodiments of the present application relate to the technical field of lithium extraction from salt lakes, for example, a method for extracting lithium from salt lakes by electrochemical deintercalation.
  • the ion sieving method is considered to be one of the feasible methods for extracting lithium from brine due to its high selectivity, low cost, and non-toxicity.
  • the adsorption capacity of the ion sieving materials currently used in industry is low, and the brine often needs to be heated for adsorption and desorption, which consumes a lot of energy.
  • Increasing the operating voltage is beneficial to improving the exchange capacity of the electrode for lithium, but it will also lead to a decrease in the selectivity of the electrode for lithium. More impurity cations gain energy to compete with lithium ions to embed into the electrode, which is easy to produce cathode polarization and reduce the purity of the recovered lithium. Although the electrode has better selectivity for lithium when operating under low voltage conditions, the exchange capacity of the electrode for lithium is low, resulting in a low extraction rate of lithium by electrochemical deintercalation.
  • the present application provides a method for electrochemical deintercalation and extraction of lithium from salt lakes.
  • the present application introduces reducing gas into the cathode brine to increase the cathode lithium intercalation rate, fully ensure the adsorption capacity of the electrode, and effectively delay the cycle extraction. Capacity decay during lithium processing.
  • lithium ions can be selectively separated from a variety of impurities.
  • the electrode potential is increased, the reaction rate of lithium extraction increases, but more impurity cations gain energy to compete with lithium ions for embedding into the electrode, and cathode polarization is easily generated, resulting in a decrease in the number of lithium ions embedded in the electrode, an increase in impurity cations, a decrease in the exchange capacity of the electrode for lithium, and a decrease in the purity of recovered lithium.
  • Lithium extraction at a lower potential is beneficial to the separation of lithium ions and impurity cations, but the required lithium extraction time is longer, and the efficiency of lithium extraction is reduced.
  • the present application adds a strong reducing gas to the brine, which promotes the reduction rate of the lithium ion sieve of the electrode material, thereby accelerating the entry of lithium ions into the crystal lattice of the electrode material to form lithium intercalation products, ensuring the lithium purity of low-voltage lithium extraction while improving the lithium extraction efficiency.
  • the recovery liquid in step (1) comprises a lithium chloride solution.
  • the lithium chloride in the recovery liquid described in the present application is used as a supporting electrolyte, and the anode and cathode are subsequently exchanged, and the lithium adsorbed by the cathode is released into the recovery liquid.
  • the concentration of lithium ions in the recovery liquid is 0.03-0.08 mol/L, for example, 0.03 mol/L, 0.04 mol/L, 0.05 mol/L, 0.06 mol/L, 0.07 mol/L or 0.08 mol/L.
  • the lithium-rich electrode in step (1) is prepared by the following method:
  • the lithium-containing active material, the conductive agent, the binder and the solvent are mixed to obtain a slurry, the slurry is coated on the surface of the carbon fiber cloth, and the slurry is dried to obtain a lithium-rich electrode.
  • the coating amount is 5-7 mg/cm 2 , for example, 5 mg/cm 2 , 5.5 mg/cm 2 , 6 mg/cm 2 , 6.5 mg/cm 2 or 7 mg/cm 2 and the like.
  • the lithium-containing active material includes any one of LiMn 2 O 4 , LiFePO 4 , Li 2 TiO 3 , LiNi 1/3 Co 1/3 Mn 1/3 O 2 or Li 7 Ti 5 O 12 or a combination of at least two thereof.
  • the conductive agent comprises carbon black.
  • the binder comprises polyvinylidene fluoride.
  • the solvent comprises N-methylpyrrolidone.
  • the drying temperature is 60-80°C, for example, 60°C, 65°C, 70°C, 75°C or 80°C.
  • the drying time is 10 to 15 hours, for example, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours or 15 hours.
  • the lithium-deficient electrode in step (1) is prepared by the following method:
  • the lithium-rich electrode is connected to the positive electrode, the AgCl electrode is connected to the negative electrode, and placed in a salt solution for constant voltage reaction. The reaction is stopped when the current decreases to 0.1 mA to obtain the lithium-poor electrode.
  • the salt solution comprises potassium chloride solution.
  • the concentration of the potassium chloride solution is 0.03-0.08 mol/L, for example, 0.03 mol/L, 0.04 mol/L, 0.05 mol/L, 0.06 mol/L, 0.07 mol/L or 0.08 mol/L.
  • the voltage of the constant voltage reaction is 1-1.5V, for example, 1V, 1.1V, 1.2V, 1.3V, 1.4V or 1.5V.
  • the voltage of the constant voltage reaction in step (1) is 0.1-0.6V, for example: 0.1V, 0.2V, 0.3V, 0.4V, 0.5V or 0.6V, etc.
  • the strong reducing gas in step (2) comprises hydrogen and/or H 2 S, preferably H 2 S.
  • the H 2 S comprises industrially generated H 2 S waste gas.
  • High-concentration H 2 S waste gas and sulfur-containing organic substances such as mercaptans, sulfides, disulfides, and cyclic sulfides are usually discharged in industrial production such as artificial fibers, natural gas purification, sulfur dyes, petroleum refining, coal gas manufacturing, sewage treatment, and papermaking. Direct discharge will cause environmental pollution and harm human health.
  • the temperature of H 2 S waste gas generated by industry is usually high.
  • the reducing gas with a high temperature can conduct heat to the brine to increase the temperature of the brine, so as to increase the activity of lithium ions in the solution, so that the lithium ions at the cathode can be embedded in the electrode faster.
  • the introduction of gas into the brine can disturb the brine and increase the convection speed of the brine, which can effectively improve the problem of concentration polarization of the solution near the surface of the lithium extraction electrode, further improve the liquid phase mass transfer efficiency of lithium ions, and make the lithium ions in the brine more smoothly, quickly and fully embedded in the cathode, thereby improving the efficiency of lithium extraction.
  • the present application uses H 2 S discharged by industrial production as a reducing agent, which can effectively treat H 2 S waste gas and avoid environmental pollution.
  • the temperature of the strong reducing gas in step (2) is 80-120°C, for example, 80°C, 90°C, 100°C, 110°C or 120°C, etc.
  • the flow rate of the strong reducing gas is 50-100 mL/min, for example, 50 mL/min, 60 mL/min, 70 mL/min, 80 mL/min, 90 mL/min or 100 mL/min.
  • the method comprises the following steps:
  • the anode chamber is injected with recycled liquid, and the cathode chamber is injected with salt lake brine, which are separated by an anion exchange membrane.
  • the lithium-rich electrode is used as the anode and the lithium-poor electrode is used as the cathode, and a constant voltage reaction is carried out at a voltage of 0.1 to 0.6 V;
  • the embodiment of the present application heats the brine by heating the reducing gas to conduct heat to increase the temperature of the brine, thereby increasing the movement rate of lithium ions in the solution, allowing the lithium ions in the cathode to be embedded in the electrode more quickly, thereby improving the liquid phase mass transfer efficiency of lithium ions, and allowing the lithium ions in the brine to be more smoothly, quickly and fully embedded in the cathode, thereby improving the lithium extraction efficiency.
  • the lithium ion concentration in the lithium-rich solution recovered by the lithium extraction method described in the embodiment of the present application can reach above 3.1 g/L, the electrode adsorption capacity can reach above 31.5 mg (Li)/g (LiMn 2 PO 4 ), and the lithium extraction reaction time can be shortened to below 5.3 h.
  • the lithium-rich electrode and the lithium-poor electrode described in the examples and comparative examples of the present application are prepared by the following method:
  • LiMn 2 O 4 powder was prepared by a high temperature solid phase method.
  • the obtained LiMn 2 O 4 was mixed with carbon black and PVDF binder in a mass ratio of 9:1:1, and N-methylpyrrolidone solvent was added for sufficient stirring.
  • the mixture was ultrasonically dispersed for 10 minutes to obtain a uniformly dispersed slurry.
  • the obtained slurry was uniformly coated on a carbon fiber cloth with a coating amount of about 6 mg/cm 2 . After coating, the mixture was dried at 70°C for 12 hours to obtain a lithium-rich electrode.
  • the obtained lithium-rich LiMn 2 O 4 electrode was connected to a positive electrode, and an AgCl electrode was connected to a negative electrode, and the mixture was placed in a 0.05 mol/L KCl solution for a constant voltage reaction of 1.2 V. The reaction was stopped when the current decreased to 0.1 mA, and a lithium-poor Li 1-x Mn 2 O 4 electrode was obtained.
  • the brine composition used is: 0.33g/L Li, 85.65g/L Na, 107.97g/L Mg, 8.45g/L K, 2.76g/L Ca, 10.54g/L SO 4 2- .
  • This embodiment provides a method for electrochemical deintercalation of lithium from salt lakes, the method comprising the following steps:
  • This embodiment provides a method for electrochemical deintercalation of lithium from salt lakes, the method comprising the following steps:
  • the lithium-rich electrode and its corresponding lithium-poor electrode are placed in a recovery liquid and salt lake brine separated by an anion exchange membrane, respectively.
  • the recovery liquid is a 0.05 mol/L LiCl solution.
  • the lithium-poor electrode is used as the cathode and the lithium-rich electrode is used as the anode.
  • a constant voltage reaction is performed at 0.6 V.
  • This embodiment provides a method for electrochemical deintercalation of lithium from salt lakes, the method comprising the following steps:
  • This embodiment provides a method for electrochemical deintercalation of lithium from salt lakes, the method comprising the following steps:
  • Example 1 The only difference between this comparative example and Example 1 is that no reducing gas is introduced, and other conditions and parameters are exactly the same as those in Example 1.
  • Example 1 The only difference between this comparative example and Example 1 is that reducing gas is introduced when the current density is 25 A/m 2 , and the other conditions and parameters are exactly the same as those in Example 1.
  • Example 1 The only difference between this comparative example and Example 1 is that reducing gas is introduced when the current density is 45 A/m 2 , and the other conditions and parameters are exactly the same as those in Example 1.
  • Example 1 The difference between this comparative example and Example 1 is that the reducing gas is not introduced and hydrazine hydrate is added, and the other conditions and parameters are exactly the same as those in Example 1.
  • the lithium ion concentration of the recovered solution in the lithium extraction method described in this application is The concentration can reach above 3.1 g/L, the electrode adsorption capacity can reach above 31.5 mg (Li)/g (LiMn 2 PO 4 ), and the lithium extraction reaction time is below 5.3 h (which can be adjusted to 2.1 h according to the lithium extraction voltage).
  • Example 1 By comparing Example 1 with Examples 7-8, it can be seen that in the lithium extraction method described in the present application, the flow rate of the reducing gas will affect the lithium extraction effect.
  • the flow rate of the reducing gas is controlled at 50-100 mL/min, the lithium extraction effect is better.
  • the flow rate of the reducing gas is too low, the reducing gas and the electrode material lithium ion sieve reaction is insufficient, affecting the adsorption capacity of the electrode; when the flow rate of the reducing gas is too high, since the reducing gas reaches a saturated state, the improvement in the lithium extraction efficiency is limited, and excessive airflow affects the contact between the electrode and the solution, thereby reducing the interface reaction of the electrode.
  • Example 1 By comparing Example 1 and Comparative Example 1, it can be seen that in the process of lithium extraction, the present application adds a strong reducing gas to the brine, which promotes the reduction rate of the lithium ion sieve of the electrode material, thereby accelerating the entry of lithium ions into the electrode material lattice to form lithium insertion products, ensuring the lithium purity of low-voltage lithium extraction while improving the lithium extraction efficiency.
  • Example 1 By comparing Example 1 with Comparative Examples 2-3, it can be seen that in the lithium extraction process of the present application, the time of introduction of the reducing gas will significantly affect the lithium extraction effect.
  • a strong reducing gas is injected into the salt lake brine, and the lithium extraction effect is better.
  • the reducing gas If the reducing gas is introduced too early, the electrochemical reaction mainly occurs on the electrode surface at this time, and the effect of the reducing agent is small. The reaction may weaken the insertion rate of lithium ions. If the reducing gas is introduced too late, the reducing gas cannot react with the lithium ion sieve of the electrode material in time, which prolongs the lithium extraction time and reduces the lithium extraction efficiency.
  • Example 1 By comparing Example 1 and Comparative Example 4, it can be seen that the introduction of reducing gas in the present application not only avoids the introduction of impurity ions compared to the addition of a reducing agent, but also the introduction of gas into the brine can increase the convection velocity of the brine, which can effectively improve the problem of concentration polarization of the solution near the surface of the lithium extraction electrode, further improve the liquid phase mass transfer efficiency of lithium ions, and make the lithium ions in the brine more smoothly, quickly and fully embedded in the cathode, thereby improving the lithium extraction efficiency.

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Abstract

本文公布一种电化学脱嵌盐湖提锂的方法，所述方法包括以下步骤：(1)分别向阳极室注入回收液，向阴极室注入盐湖卤水，用阴离子交换膜隔开，以富锂态电极为阳极，贫锂态电极为阴极，进行恒电压反应；(2)恒电压反应电流密度降低至30-40A/m2时，在盐湖卤水中注入强还原性气体；(3)待电流密度降低至5A/m2时断电停止反应，调换阴阳极重复进行恒电压反应，得到富锂溶液，本申请通过阴极卤水通入还原性气体，提高阴极嵌锂速率，充分保证电极的吸附容量，避免了循环提锂过程中容量衰减的问题。

Description

一种电化学脱嵌盐湖提锂的方法 技术领域
本申请实施例涉及盐湖提锂技术领域，例如一种电化学脱嵌盐湖提锂的方法。
背景技术
近年来，随着新能源汽车、化学储能的快速发展，对锂的需求量激增。盐湖卤水赋存储量巨大的锂资源(约占全球锂资源储量的70％)，因此盐湖提锂越来越受到人们的重视。针对盐湖锂资源的开发，发明了诸如蒸发法、吸附法、溶剂萃取法、电渗析法和膜分离法等多种工艺。蒸发法适合从低镁锂比溶液中提取锂(Mg/Li<6)，即便如此在蒸发过程中约有50％的锂会损失在蒸发结晶盐中，而对高Mg/Li比值卤水的处理情况则更为严重。
电渗析法和膜分离法虽然环保，但卤水需要用大量的水稀释，由于同为一价阳离子Li+和Na+/K+难以通过膜分离，因此需要将卤水中的Na+和K+通过蒸发法进行脱除，导致锂的大量损失。而对于溶剂萃取法，由于盐水的粘度较高，容易造成乳化现象。虽然通过离心萃取技术可以在一定程度上缓解这一现象，但有机萃取剂在卤水中具有一定溶解度，对环境带来潜在的污染。离子筛吸法因其选择性高、成本低、无毒等特点，被认为是盐水提锂的可行方法之一，但目前工业使用的离子筛材料的吸附容量低，且常需要对卤水进行升温吸附和解吸，能耗高。
提高操作电压有利于提升电极对锂的交换容量，但也会导致电极对锂的选择性下降，更多的杂质阳离子获得能量与锂离子竞争嵌入电极中，容易产生阴极极化，降低回收锂的纯度。在低电压条件下操作虽然电极对锂的选择性较好，但电极对锂的交换容量却较低，导致电化学脱嵌法对锂的提取速率较低。
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盐湖提锂的方法，本申请通过阴极卤水通入还原性气体，提高阴极嵌锂速率，充分保证电极的吸附容量，有效延缓了循环提 锂过程中容量的衰减。
第一方面，本申请实施例提供了一种电化学脱嵌盐湖提锂的方法，所述方法包括以下步骤：
(1)分别向阳极室注入回收液，向阴极室注入盐湖卤水，用阴离子交换膜隔开，以富锂态电极为阳极，贫锂态电极为阴极，进行恒电压反应；
(2)恒电压反应电流密度降低至30-40A/m2时，在盐湖卤水中注入强还原性气体；
(3)待电流密度降低至5A/m2时断电停止反应，调换阴阳极重复进行恒电压反应，得到富锂溶液。
卤水中存在多种Na、K、Mg共存阳离子，使用电化学脱嵌提锂时，只要适当控制电压，就可以选择性的从多种杂质中分离出锂离子，当提高电极电势时，提锂的反应速度增加，但更多的杂质阳离子获得能量与锂离子竞争嵌入电极中，且容易产生阴极极化，导致电极中嵌入的锂离子减少，杂质阳离子增多，电极对锂的交换容量减少，回收锂的纯度减小，在较低的电势下进行提锂有利于锂离子和杂质阳离子的分离，但所需的提锂时间较长，提锂的效率降低，本申请在提锂过程中，在卤水中加入强还原性气体，促进了电极材料锂离子筛的还原速率，从而加快了锂离子进入电极材料晶格形成嵌锂产物，保证了低电压提锂的锂纯度同时提高了提锂效率。
优选地，步骤(1)所述回收液包括氯化锂溶液。
本申请所述回收液中的氯化锂作为支持电解质，后续交换阴阳极，阴极吸附的锂脱出进入回收液中。
优选地，所述回收液中锂离子的浓度为0.03～0.08mol/L，例如：0.03mol/L、0.04mol/L、0.05mol/L、0.06mol/L、0.07mol/L或0.08mol/L等。
优选地，步骤(1)所述富锂态电极通过如下方法制得：
将含锂活性物质、导电剂、粘结剂和溶剂混合得到浆料，将所述浆料涂覆在碳纤维布表面，烘干得到富锂态电极。
优选地，所述涂覆量为5～7mg/cm2，例如：5mg/cm2、5.5mg/cm2、6mg/cm2、6.5mg/cm2或7mg/cm2等。
优选地，所述含锂活性物质包括LiMn2O4、LiFePO4、Li2TiO3、LiNi1/3Co1/3Mn1/3O2或Li7Ti5O12中的任意一种或至少两种的组合。
优选地，所述导电剂包括炭黑。
优选地，所述粘结剂包括聚偏氟乙烯。
优选地，所述溶剂包括N-甲基吡咯烷酮。
优选地，所述烘干的温度为60～80℃，例如：60℃、65℃、70℃、75℃或80℃等。
优选地，所述烘干的时间为10～15h，例如：10h、11h、12h、13h、14h或15h等。
优选地，步骤(1)所述贫锂态电极通过如下方法制得：
将富锂态电极接正极，AgCl电极接负极置于盐溶液溶液中进行恒电压反应，至电流降低至0.1mA时停止反应，得到所述贫锂态电极。
优选地，所述盐溶液包括氯化钾溶液。
优选地，所述氯化钾溶液的浓度为0.03～0.08mol/L，例如：0.03mol/L、0.04mol/L、0.05mol/L、0.06mol/L、0.07mol/L或0.08mol/L等。
优选地，所述恒电压反应的电压为1～1.5V，例如：1V、1.1V、1.2V、1.3V、1.4V或1.5V等。
优选地，步骤(1)所述恒电压反应的电压为0.1～0.6V，例如：0.1V、0.2V、0.3V、0.4V、0.5V或0.6V等。
优选地，步骤(2)所述强还原性气体包括氢气和/或H2S，优选为H2S。
优选地，所述H2S包括工业产生的H2S废气。
在人造纤维、天然气净化、硫化染料、石油精炼、煤气制造、污水处理、造纸等工业生产中通常会排放出高浓度的H2S废气，及硫醇、硫醚、二硫醚、环状硫化物等含硫有机物，直接排放会造成环境污染和危害人体健康。工业产生的H2S废气的温度通常较高，具有较高温度的还原性气体可以对卤水进行热传导使卤水的温度升高，以提高溶液内锂离子的活度，使阴极的锂离子能够更快的嵌入到电极中，此外，在卤水中通入气体可以对卤水进行扰动，增加卤水的对流速度，可以使提锂电极表面附近的溶液被浓差极化的问题得到有效改善，进一步提高了锂离子的液相传质效率，使卤水中的锂离子更加顺畅快速充分的嵌入阴极，提高了提锂效率。本申请使用工业生产所排放的H2S，作为还原剂，可以有效处理H2S废气，避免了环境污染。
优选地，步骤(2)所述强还原性气体的温度为80～120℃，例如：80℃、90℃、 100℃、110℃或120℃等。
优选地，所述强还原性气体的流量为50～100mL/min，例如：50mL/min、60mL/min、70mL/min、80mL/min、90mL/min或100mL/min等。
作为本申请的优选方案，所述方法包括以下步骤：
(1)阳极室注入回收液，阴极室注入盐湖卤水，用阴离子交换膜隔开，以富锂态电极为阳极，贫锂态电极为阴极，在0.1～0.6V电压下恒电压反应；
(2)恒电压反应电流密度降低至30-40A/m2时，在盐湖卤水中以50～100mL/min的流量注入80～120℃的强还原性气体，电流密度降低至5A/m2时停止反应，调换阴阳极重复进行恒电压反应，得到富锂溶液。
相对于相关技术，本申请实施例具有以下有益效果：
(1)本申请实施例通过加热还原性气体，可以对卤水进行热传导使卤水的温度升高，以提高溶液内锂离子的运动速率，使阴极的锂离子能够更快的嵌入到电极中，提高了锂离子的液相传质效率，使卤水中的锂离子更加顺畅快速充分的嵌入阴极，提高了提锂效率。
(2)本申请实施例所述提锂方法回收得到富锂溶液中锂离子浓度可达3.1g/L以上，电极吸附容量可达31.5mg(Li)/g(LiMn2PO4)以上，提锂反应时间可缩短至5.3h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。
本申请实施例和对比例所述富锂态电极和贫锂态电极通过如下方法制得：
以高温固相法制备LiMn2O4粉体，以所得LiMn2O4与炭黑、PVDF粘结剂，按质量比9：1：1混合，加入N-甲基吡咯烷酮溶剂充分搅拌，并超声分散10min得到分散均匀的浆状物，将所得浆状物均匀涂覆的碳纤维布上，涂覆量约为6mg/cm2，涂覆完成后在70℃下进行烘干12h，得到富锂态电极；将所得富锂态LiMn2O4电极接正极，AgCl电极接负极置于0.05mol/L KCl溶液中进行恒压1.2V反应，至电流降低至0.1mA时停止反应，即得贫锂态Li1-xMn2O4电极。
使用的卤水成分为：0.33g/L Li、85.65g/L Na、107.97g/L Mg、8.45g/L K、 2.76g/L Ca、10.54g/L SO4 2-。
实施例1
本实施例提供了一种电化学脱嵌盐湖提锂的方法，所述方法包括以下步骤：
(1)分别将富锂态电极和其相对应的贫锂态电极置于使用阴离子交换膜隔离的回收液和盐湖卤水中，回收液为0.05mol/L LiCl溶液，将贫锂态电极作为阴极，富锂态电极作为阳极，在0.3V进行恒电压反应；
(2)当恒电压反应进行至电流密度降低至35A/m2时，使用注气装置往卤水中通入流量为75ml/min的H2S气体，气体加热温度为95℃，观察电流密度降低至5A/m2时断电停止反应，随后将富锂态电极和贫锂态电极取出并进行清洗后，将阴阳极进行互换，重复进行恒电压反应至卤水中锂浓度达到预期值，得到富锂溶液。
实施例2
本实施例提供了一种电化学脱嵌盐湖提锂的方法，所述方法包括以下步骤：
(1)分别将富锂态电极和其相对应的贫锂态电极置于使用阴离子交换膜隔离的回收液和盐湖卤水中，回收液为0.05mol/L LiCl溶液，将贫锂态电极作为阴极，富锂态电极作为阳极，在0.6V进行恒电压反应；
(2)当恒电压反应进行至电流密度降低至30A/m2时，使用注气装置往卤水中通入流量为50ml/min H2S气体，气体加热温度为80℃，观察电流密度降低至5A/m2时断电停止反应，随后将富锂态电极和贫锂态电极取出并进行清洗后，将阴阳极进行互换，重复进行恒电压反应至卤水中锂浓度达到预期值，得到富锂溶液。
实施例3
本实施例提供了一种电化学脱嵌盐湖提锂的方法，所述方法包括以下步骤：
(1)分别将富锂态电极和其相对应的贫锂态电极置于使用阴离子交换膜隔离的回收液和盐湖卤水中，回收液为0.05mol/L LiCl溶液，将贫锂态电极作为阴极，富锂态电极作为阳极，在0.1V进行恒电压反应；
(2)当恒电压反应进行至电流密度降低至40A/m2时，使用注气装置往卤水中通入流量为100ml/min的H2S气体，气体加热温度为120℃，直至电流密度 降低至5A/m2时断电停止反应，随后将富锂态电极和贫锂态电极取出并进行清洗后，将阴阳极进行互换，重复进行恒电压反应至卤水中锂浓度达到预期值，得到富锂溶液。
实施例4
本实施例提供了一种电化学脱嵌盐湖提锂的方法，所述方法包括以下步骤：
(1)分别将富锂态电极和其相对应的贫锂态电极置于使用阴离子交换膜隔离的回收液和盐湖卤水中，回收液为0.05mol/L LiCl溶液，将贫锂态电极作为阴极，富锂态电极作为阳极，在0.3V进行恒电压反应；
(2)当恒电压反应进行至电流密度降低至35A/m2时，使用注气装置往卤水中通入流量为75ml/min的H2气体，气体加热温度为120℃，观察电流密度降低至5A/m2时断电停止反应，随后将富锂态电极和贫锂态电极取出并进行清洗后，将阴阳极进行互换，重复进行恒电压反应至卤水中锂浓度达到预期值，得到富锂溶液。
实施例5
本实施例与实施例1区别仅在于，还原气体的加热温度为70℃，其他条件与参数与实施例1完全相同。
实施例6
本实施例与实施例1区别仅在于，还原气体的加热温度为130℃，其他条件与参数与实施例1完全相同。
实施例7
本实施例与实施例1区别仅在于，还原气体的流速为30mL/min，其他条件与参数与实施例1完全相同。
实施例8
本实施例与实施例1区别仅在于，还原气体的流速为120mL/min，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，不通入还原气体，其他条件与参数与实施例1完全相同。
对比例2
本对比例与实施例1区别仅在于，在电流密度为25A/m2时，通入还原气体，其他条件与参数与实施例1完全相同。
对比例3
本对比例与实施例1区别仅在于，在电流密度为45A/m2时，通入还原气体，其他条件与参数与实施例1完全相同。
对比例4
本对比例与实施例1区别仅在于，不通入还原气体，加入水合肼，其他条件与参数与实施例1完全相同。
性能测试：
实施例和对比例所述提锂实验的各指标如表1所示：
表1
由表1可以看出，由实施例1-4可得，本申请所述提锂方法回收液锂离子浓 度可达3.1g/L以上，电极吸附容量可达31.5mg(Li)/g(LiMn2PO4)以上，提锂反应时间在5.3h以下(可根据提锂电压调整至2.1h)。
由实施例1和实施例5-6对比可得，本申请所述提锂方法中，还原气体的加热温度会影响提锂效果，将还原气体的加热温度控制在80～120℃，提锂效果较好，若还原气体的加热温度过低，反应速率降低，提锂所需时间增加，增加还原气体的加热温度，反应加速，若还原气体的加热温度过高，对反应速率的提升有限，且会使溶液的热传导加快，从而使阳极液的温度上升，不利于阴阳极的脱嵌容量保持一致。
由实施例1和实施例7-8对比可得，本申请所述提锂方法中，还原气体的流量会影响提锂效果，将还原气体的流量控制在50-100mL/min，提锂效果较好，还原气体的流量过低时，还原气体和电极材料锂离子筛反应不充分，影响电极的吸附容量；还原气体的流量过高时，由于还原气体达到饱和状态，对提锂效率的提升有限，且过量的气流会影响电极与溶液的接触，从而降低了电极的界面反应。
由实施例1和对比例1对比可得，本申请在提锂过程中，在卤水中加入强还原性气体，促进了电极材料锂离子筛的还原速率，从而加快了锂离子进入电极材料晶格形成嵌锂产物，保证了低电压提锂的锂纯度同时提高了提锂效率。
由实施例1和对比例2-3对比可得，本申请在提锂过程中，还原气体的通入时间会明显影响提锂效果，当电流密度降低至30-40A/m2时，在盐湖卤水中注入强还原性气体，提锂效果较好，若通入还原气体的时机过早，此时电极表面主要发生电化学反应，还原剂的作用较小，其反应有可能减弱锂离子的嵌入速率，若通入还原气体的时机过晚，还原气体不能及时与电极材料锂离子筛发生反应，延长了提锂时间，降低提锂效率。
由实施例1和对比例4对比可得，本申请通入还原气体相较于加入还原剂不仅避免了杂质离子的引入，同时在卤水中通入气体可以增加卤水的对流速度，可以有效改善提锂电极表面附近的溶液被浓差极化的问题，进一步提高了锂离子的液相传质效率，使卤水中的锂离子更加顺畅快速充分的嵌入阴极，提高了提锂效率。
以上所述仅为本申请的具体实施方式，但本申请的保护范围并不局限于此， 所属技术领域的技术人员应该明了，任何属于本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到的变化或替换，均落在本申请的保护范围和公开范围之内。

Claims (14)

  1. 一种电化学脱嵌盐湖提锂的方法，其包括以下步骤：
    (1)分别向阳极室注入回收液，向阴极室注入盐湖卤水，用阴离子交换膜隔开，以富锂态电极为阳极，贫锂态电极为阴极，进行恒电压反应；
    (2)恒电压反应电流密度降低至30-40A/m2时，在盐湖卤水中注入强还原性气体；
    (3)待电流密度降低至5A/m2时断电停止反应，调换阴阳极重复进行恒电压反应，得到富锂溶液。
  2. 如权利要求1所述的方法，其中，步骤(1)所述回收液包括氯化锂溶液。
  3. 如权利要求1或2所述的方法，其中，所述回收液中锂离子的浓度为0.03～0.08mol/L。
  4. 如权利要求1-3任一项所述的方法，其中，步骤(1)所述富锂态电极通过以下方法制得：
    将含锂活性物质、导电剂、粘结剂和溶剂混合得到浆料，将所述浆料涂覆在碳纤维布表面，烘干得到富锂态电极。
  5. 根据权利要求4所述的方法，其中，所述涂覆的涂覆量为5～7mg/cm2。
  6. 如权利要求4或5所述的方法，其中，所述含锂活性物质包括LiMn2O4、LiFePO4、Li2TiO3、LiNi1/3Co1/3Mn1/3O2或Li7Ti5O12中的任意一种或多种的组合；
    优选地，所述导电剂包括炭黑；
    优选地，所述粘结剂包括聚偏氟乙烯；
    优选地，所述溶剂包括N-甲基吡咯烷酮；
    优选地，所述烘干的温度为60～80℃；
    优选地，所述烘干的时间为10～15h。
  7. 如权利要求1-6任一项所述的方法，其中，步骤(1)所述贫锂态电极通过如下方法制得：
    将富锂态电极接正极，AgCl电极接负极置于盐溶液溶液中进行恒电压反应，至电流降低至0.1mA时停止反应，得到所述贫锂态电极。
  8. 如权利要求7所述的方法，其中，所述盐溶液包括氯化钾溶液；
    优选地，所述氯化钾溶液的浓度为0.03～0.08mol/L。
  9. 如权利要求7或8所述的方法，其中，所述恒电压反应的电压为1～1.5V。
  10. 如权利要求1-9任一项所述的方法，其中，步骤(1)所述恒电压反应的电压为0.1～0.6V。
  11. 如权利要求1-10任一项所述的方法，其中，步骤(2)所述强还原性气体包括氢气和/或H2S，优选为H2S；
    优选地，所述H2S包括工业产生的H2S废气。
  12. 如权利要求1-11任一项所述的方法，其中，步骤(2)所述强还原性气体的温度为80～120℃。
  13. 如权利要求1-12任一项所述的方法，其中，所述强还原性气体的流量为50～100mL/min。
  14. 如权利要求1-13任一项所述的方法，其包括以下步骤：
    (1)分别向阳极室注入回收液，向阴极室注入含锂盐湖卤水，用阴离子交换膜隔开，以富锂态电极为阳极，贫锂态电极为阴极，在0.1～0.6V电压下恒电压反应；
    (2)恒电压反应电流密度降低至30-40A/m2时，在盐湖卤水中以50～100mL/min的流量注入80～120℃的强还原性气体，电流密度降低至5A/m2时停止反应，调换阴阳极重复进行恒电压反应，得到富锂溶液。
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DE102012212770A1 (de) * 2012-07-20 2014-05-15 RUHR-UNIVERSITäT BOCHUM Verfahren und vorrichtung für die gewinnung von lithium aus salzlösungen
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CN109267086A (zh) * 2018-10-30 2019-01-25 吉首大学 一种盐湖卤水中镁/锂分离及富集锂的装置及方法
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CN115818801A (zh) * 2022-12-20 2023-03-21 中南大学 一种从盐湖卤水中提取锂的方法

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