Method for directly preparing lithium hydroxide through electrochemical method and preparation method of inert anode of lithium hydroxide

Abstract

The invention relates to the field of electrochemical lithium extraction and lithium hydroxide preparation, and discloses a method for directly preparing lithium hydroxide by an electrochemical process, which comprises the following steps: providing lithium-containing brine, and filtering to remove solid particles and suspended solids; the filtered lithium-containing brine is introduced into a lithium suction flow channel of electrochemical lithium extraction equipment, the lithium suction flow channel comprises an active electrode and an inert electrode, the active electrode is connected with a negative electrode of a direct-current power supply, and the inert electrode is connected with a positive electrode of the direct-current power supply; enriching lithium ions of the lithium-containing brine through an active electrode under the action of an electric field; and after lithium suction is completed, the lithium suction flow channel is washed with desalted water. According to the invention, the original brine is directly introduced into electrochemical lithium extraction equipment, and an electrochemical method in which an active electrode is matched with an inert electrode is adopted, so that rapid selective enrichment and release of lithium ions are realized. The technology does not need complex brine evaporation and concentration or multi-step conversion, avoids the problems of tedious procedures and large occupied area of equipment, and effectively reduces the production cycle and energy consumption.

Description

Technical Field

[0001] The invention relates to the technical field of electrochemical lithium extraction and lithium hydroxide preparation, and specifically to a method for directly preparing lithium hydroxide by an electrochemical method and a method for preparing an inert anode thereof. Background Art

[0002] With the rapid development of the global new energy industry, the demand for lithium resources continues to grow. As an important raw material for lithium-ion batteries, lithium hydroxide plays a key role in battery manufacturing, energy storage and other fields. Salt lake brine has gradually become an important source of lithium resource extraction due to its rich lithium reserves. However, the traditional salt lake lithium extraction process is complex and energy-intensive. At the same time, there is still much room for improvement in the utilization efficiency of lithium resources. It is particularly urgent to develop efficient, economical and environmentally friendly lithium hydroxide preparation technology.

[0003] In the prior art, the methods for extracting lithium hydroxide mainly include adsorption, evaporation and concentration, and electrochemical methods. Among them, the adsorption method recovers lithium through selective adsorption resin, but the process cycle is long, and the adsorption effect is easily affected by impurity ions; the evaporation and concentration method relies on high-temperature evaporation steps, which consumes huge energy and has a complicated process; the electrochemical method has gradually attracted attention in recent years. It takes the migration and separation of lithium ions under the action of an electric field as its core principle and has certain efficiency advantages. However, existing electrochemical lithium extraction equipment usually relies on expensive electrode materials (such as platinum or graphite electrodes), and there is still a lot of room for improvement in the efficiency and resource utilization of the lithium absorption and release stages.

[0004] In the existing electrochemical lithium extraction process, equipment operation stability and cost control are the main technical bottlenecks. For example, the coating of the commonly used inert anode material is easy to fall off, has a short life, and its corrosion resistance is insufficient, which not only greatly increases the operating cost, but also limits the long-term industrial application of the process. Therefore, how to develop an efficient, low-cost and corrosion-resistant inert anode and achieve efficient utilization of low-lithium concentration salt lake brine has become an urgent problem to be solved. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a method for directly preparing lithium hydroxide by an electrochemical method and a method for preparing an inert anode thereof. The existing electrochemical lithium extraction process has the problems of short life of the inert anode, insufficient corrosion resistance and low extraction efficiency of brine with low lithium concentration.

[0006] To achieve the above objectives, the present invention is implemented by the following technical scheme: A method for directly preparing lithium hydroxide by electrochemical method, comprising the following steps: Provide lithium-containing brine and filter to remove solid particles and suspended matter; Passing the filtered lithium-containing brine into a lithium absorption channel of an electrochemical lithium extraction device, wherein the lithium absorption channel includes an active electrode and an inert electrode, wherein the active electrode is connected to the negative electrode of a DC power supply, and the inert electrode is connected to the positive electrode of the DC power supply; Under the action of electric field, lithium ions are enriched through active electrodes in lithium-containing brine; After lithium absorption is completed, the lithium absorption channel is flushed with desalted water; Passing a lithium-discharging receiving solution into a lithium-discharging flow channel, wherein the lithium-discharging flow channel includes an active electrode and an inert electrode, wherein the active electrode is connected to the positive electrode of a DC power supply, and the inert electrode is connected to the negative electrode of the DC power supply, and lithium ions are released from the active electrode to the lithium-discharging receiving solution; After the lithium discharge is completed, the lithium discharge channel is cleaned with desalted water and the cleaning water is recycled.

[0007] Preferably, in the lithium absorption step, the operating voltage in the lithium absorption channel is 2.5-3.5V, and the current density is 10-20mA / cm 2 The lithium absorption time is 60-90 minutes.

[0008] Preferably, in the lithium discharge step, the operating voltage in the lithium discharge flow channel is 3.5-5V, and the current density is 20-30mA / cm 2 The lithium release time is 40-60 minutes.

[0009] Preferably, the lithium receiving solution is a lithium hydroxide solution with a concentration of 0.1%-0.5%.

[0010] Preferably, the lithium-containing tail liquid generated after the lithium absorption step is subjected to secondary lithium absorption through multiple lithium absorption channels connected in series, and the lithium concentration is reduced by 10%-20% after each stage of lithium absorption.

[0011] A method for preparing an inert anode comprises the following steps: Providing a current collector, wherein the current collector is made of iron or aluminum; Pre-treating the surface of the current collector, wherein the pre-treatment includes sandblasting or chemical etching, and the surface roughness is Ra1.0-2.0 μm; preparing a conductive coating material, mixing a thermoplastic conductive polymer with a conductive filler, wherein the conductive filler is carbon black, graphite or carbon nanotubes, and the conductive filler accounts for 5%-20%; Applying the conductive coating material to both sides of the current collector by heating and pressing, the heating temperature is 180-250° C., and the pressure is 20-50 MPa; After coating, cooling and surface treatment are performed to obtain an inert anode.

[0012] Preferably, the conductive polymer is one or more of PVDF, PTFE, PE or PP.

[0013] Preferably, the thickness of the conductive coating is 10-50 μm.

[0014] Preferably, in the pretreatment step, the current collector is sandblasted or chemically etched and then cleaned and dried.

[0015] Preferably, after the cooling step, the surface of the inert anode is polished to a surface roughness of Ra 0.5-1.5 μm.

[0016] The present invention provides a method for directly preparing lithium hydroxide by electrochemical method and a method for preparing an inert anode thereof. The method has the following beneficial effects: 1. The present invention directly introduces raw brine into the electrochemical lithium extraction equipment and adopts an electrochemical method of active electrodes and inert electrodes to achieve rapid selective enrichment and release of lithium ions. This technology does not require complicated brine evaporation and concentration or multi-step conversion. Compared with the existing technical solutions that rely on evaporation or electrodialysis processes, it avoids the problems of cumbersome procedures and large equipment space, and effectively reduces the production cycle and energy consumption.

[0017] 2. The electrochemical process used in the present invention can directly extract lithium hydroxide solution from brine with a lithium content as low as 200 mg / L. No high-purity lithium salt raw materials are required, and the inert anode used in the process is made of iron or aluminum as a substrate combined with an economical conductive coating material. Compared with traditional technologies that rely on high-cost platinum or graphite electrodes, it significantly reduces equipment and operating costs, while broadening the range of raw materials for lithium resource utilization.

[0018] 3. The present invention adopts an inert anode with a sandwich structure, and the conductive coating is formed by high temperature and high pressure pressure coating to form a uniform and dense conductive layer. This design exhibits excellent corrosion resistance and mechanical stability in harsh electrochemical environments. Compared with the existing DSA electrode, it effectively solves the problems of coating shedding and short life, and significantly improves the electrochemical stability and long-term performance of the electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 One of the schematic flow charts of the method of the present invention; Figure 2 This is the second schematic flow chart of the method of the present invention. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the specification of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] Please see attached Figure 1-2The embodiment of the present invention provides a method for directly preparing lithium hydroxide by electrochemical method and a method for preparing an inert anode thereof, including:

[0022] 1. Preparation method of lithium hydroxide 1.1 Lithium absorption process Steps: Initial treatment of lithium-containing brine: Filter brine with lithium content ≥200 mg / L through a 10-20 μm filter membrane to remove large particle impurities and suspended matter.

[0023] Brine enters the lithium absorption channel: the lithium absorption channel is composed of an active electrode and an inert electrode, the active electrode is connected to the negative electrode of the DC power supply, and the inert electrode is connected to the positive electrode of the DC power supply.

[0024] Lithium ion migration under electric field: at 2.5-3.5V and 10-20mA / cm 2 At a current density of , the lithium ions in the brine migrate to the active electrode under the action of the electric field and are enriched.

[0025] Cleaning step: After lithium absorption is completed, the flow channel is cleaned with desalted water to remove unabsorbed lithium ions and impurities.

[0026] The migration of lithium ions is based on the selective separation of anions and cations induced by an electric field. Due to the small hydration radius of lithium ions (about 0.38nm), the active electrode preferentially adsorbs lithium ions by regulating the surface pore size and charge characteristics, while suppressing the adsorption of ions with larger hydration radius (such as Na + Mg 2+ ) migration.

[0027] The ionic capacitance mechanism on the electrode surface enhances the adsorption capacity of lithium ions while reducing the competitive adsorption of other ions, ensuring the enrichment efficiency of lithium ions.

[0028] 1.2 Lithium release process Steps: Preparation of lithium release receiving solution: Pass a lithium hydroxide solution with a concentration of 0.1%-0.5% into the lithium release flow channel.

[0029] Electrode polarity reversal: the active electrode is connected to the positive pole of the DC power supply, and the inert electrode is connected to the negative pole.

[0030] Lithium ion release: Lithium ions accumulated on the active electrode enter the lithium release solution through the action of the electric field.

[0031] Cleaning steps: After the lithium discharge is completed, the lithium discharge channel is rinsed with desalted water and the cleaning water is recycled.

[0032] After the electrode polarity is reversed, the lithium ions accumulated on the active electrode are released into the lithium-discharging solution through the electric field. This process depends on the change of the double-layer charge of the active electrode. The desorption of lithium ions is closely related to the change of polarity on the electrode surface, that is, the change from adsorption state to solution state.

[0033] Using a low-concentration lithium hydroxide solution as the lithium-discharging solution can further reduce the electrochemical overpotential at the electrode interface, increase the lithium ion release rate, and avoid the formation of by-products.

[0034] 1.3 System Optimization Steps: A multi-stage series process is adopted: during the lithium absorption process, the tail liquid is introduced from the outlet of the first-stage lithium absorption flow channel into the next-stage lithium absorption flow channel to gradually reduce the lithium concentration in the tail liquid.

[0035] Recycling of cleaning water: The cleaning water generated during the absorption and release of lithium is filtered and then recycled into the process.

[0036] The purpose of multi-stage series lithium absorption is to maximize the recovery of lithium ions in brine. The lithium concentration in the tail liquid is reduced by step-by-step adsorption. The lithium ion concentration decreases after each stage of adsorption, which is in line with the gradient-driven diffusion mechanism.

[0037] The recycling of cleaning water is based on the selective filtration and purification of lithium-containing aqueous solutions, which can effectively reduce the amount of process water while ensuring the overall economy of the system.

[0038] 2. Preparation method of inert anode 2.1 Selection and pretreatment of current collector Steps: The current collector uses iron or aluminum as a substrate, and the surface is sandblasted or chemically etched.

[0039] The roughness of the current collector surface after sandblasting is controlled at Ra1.0-2.0 μm to enhance the adhesion of the conductive coating.

[0040] The selection of current collectors needs to comprehensively consider conductivity, mechanical strength and economy. Iron and aluminum have excellent conductivity and processability, and are relatively low in cost.

[0041] Surface roughening (by sandblasting or etching) can significantly increase the physical fit between the coating and the substrate, while also enhancing adhesion through chemical bonding.

[0042] 2.2 Preparation of conductive coating materials Steps: Conductive coatings are prepared by mixing thermoplastic polymers (such as PVDF, PTFE, PE) with conductive fillers (carbon black, graphite, carbon nanotubes).

[0043] The conductive filler accounts for 5%-20% of the coating weight, and the mixed material is heated to 80-120° C. in an internal mixer and stirred evenly.

[0044] The main function of the conductive coating is to improve the conductivity of the inert anode and provide electrochemical stability. Conductive fillers (such as carbon black and graphite) form a conductive network in the coating, significantly reducing the coating resistance.

[0045] Thermoplastic polymers offer excellent chemical stability, enabling long-term use in corrosive brine environments without significant degradation.

[0046] 2.3 Coating and pressure coating Steps: The conductive coating material is uniformly coated on both sides of the current collector with a coating thickness of 10-50 μm.

[0047] After coating, heating and pressure coating are carried out under the conditions of 180-250°C and 20-50MPa.

[0048] Controlling the coating thickness to 10-50 μm can reduce material usage and production costs while maintaining conductivity and coating stability.

[0049] The high temperature and high pressure environment of heated pressure coating enables the conductive filler to form a dense conductive network in the polymer matrix, while improving the mechanical strength of the coating.

[0050] 2.4 Cooling and surface treatment Steps: The inert anode after press coating was cooled naturally to room temperature and the surface impurities were washed by deionized water.

[0051] After cooling, the coating surface is polished and the roughness is controlled at Ra0.5-1.5μm.

[0052] The cooling process controls the release of stress within the coating and avoids coating peeling due to excessive temperature difference.

[0053] Grinding treatment can further improve the uniformity of the coating and reduce the impact of surface defects on electrochemical performance.

[0054] 3. Overall summary of technical mechanism Electrochemical lithium extraction mechanism: The electric field drives the selective migration of lithium ions from the lithium-containing brine and achieves adsorption and enrichment through the active electrode; during the lithium release process, the lithium ions are desorbed and enter the lithium release receiving solution through the reverse action of the electric field.

[0055] Inert anode mechanism: The core of the inert anode lies in the material selection and structural design of the conductive coating. The conductive network is constructed by conductive fillers to improve the conductivity of the coating. At the same time, the bonding strength between the substrate and the coating directly determines the stability and service life of the electrode.

[0056] Example 1: Preparation of lithium hydroxide directly from low lithium content brine Raw material handling The salt lake brine with a lithium content of 250 mg / L was sampled and first filtered through a 10 μm pore size filter membrane to remove impurities and suspended particles. The filtered brine was directly stored in a stainless steel storage tank for future use.

[0057] Lithium absorption operation The brine was passed into the lithium absorption channel of the electrochemical lithium extraction equipment at a flow rate of 1.5L / min. The active electrode was nickel-cobalt oxide, connected to the negative pole of the DC power supply, and the inert electrode was a sandwich anode, connected to the positive pole of the DC power supply. The operating voltage was set to 3V and the current density was 15mA / cm 2 The lithium absorption time is 70 minutes. After the lithium absorption is completed, the flow channel is rinsed with 0.5L of desalted water, and the cleaning solution is discarded.

[0058] Lithium discharge operation The lithium receiving solution used was a lithium hydroxide solution with a concentration of 0.2%. The lithium solution was passed into the lithium discharge channel at a flow rate of 1L / min. The polarity of the DC power supply was switched, the active electrode was connected to the positive electrode, and the inert electrode was connected to the negative electrode. The working voltage was adjusted to 4.5V, and the current density was increased to 20mA / cm 2 The lithium release time is 45 minutes, and the receiving solution is collected and used for later use. When cleaning the flow channel, 0.5L desalted water is used, and the cleaning water is recycled.

[0059] The concentration of lithium hydroxide in the lithium receiving solution is increased to 0.8%, and the total recovery rate of lithium ions is 92%. Compared with the traditional concentration and evaporation process, the direct lithium extraction operation reduces energy consumption by 50%, the lithium absorption and release process is simple, and the equipment loss is small.

[0060] Example 2: Multi-stage series lithium extraction process to improve tail liquid utilization Primary lithium absorption Oilfield wastewater with a lithium concentration of 300 mg / L was used. The wastewater was filtered through a 20 μm pore size filter membrane and directly sent to the first lithium absorption channel. The flow rate was set to 2 L / min. The working voltage was set to 3 V and the current density was 12 mA / cm 2 The lithium absorption time was 60 minutes, and the lithium concentration was reduced to 100 mg / L.

[0061] Secondary lithium absorption The primary tail liquid enters the second lithium absorption channel. The lithium absorption conditions are basically the same, the voltage is maintained at 3V, and the current density is increased to 15mA / cm 2The tail liquid lithium absorption time was controlled at 50 minutes, and the lithium concentration was further reduced to 30 mg / L.

[0062] Lithium release and collection The active electrodes in the primary and secondary lithium absorption channels switch polarity to perform lithium discharge operation. The lithium discharge receiving solution is 0.3% lithium hydroxide solution, the receiving solution flow rate is set to 1.2L / min, the working voltage is 5V, and the lithium discharge time is 40 minutes and 35 minutes respectively.

[0063] The multi-stage series operation increases the total lithium recovery rate to more than 95%. The lithium concentration of the tail liquid is less than 20 mg / L, meeting the wastewater discharge standard. Compared with the single-stage adsorption process, the resource utilization rate is significantly improved, reducing the wastewater pollution problem.

[0064] Example 3: Preparation and durability test of inert anode Substrate treatment An aluminum sheet with a thickness of 0.8 mm was used as the current collector, and the surface of the aluminum sheet was processed by sandblasting equipment, and the roughness was controlled at Ra1.5 μm. The aluminum sheet after sandblasting was washed with deionized water and dried for use.

[0065] Coating preparation The conductive coating formula is: PVDF accounts for 70%, carbon black accounts for 10%, and graphite accounts for 20%. After mixing the above materials, heat to 100°C in an internal mixer and stir for 60 minutes to obtain a uniform conductive coating material.

[0066] Compression molding The conductive coating material is applied to both sides of the aluminum sheet, and the coating thickness is controlled at 20 μm. Then, the coating is carried out in a heated pressure coating device, with the temperature set to 200°C and the pressure set to 30 MPa for 10 minutes. After cooling, the electrode surface is polished, and the roughness is controlled at Ra1 μm.

[0067] Electrochemical stability test The prepared inert anode was placed in a simulated lithium-containing brine for long-term stability testing. The electrolysis conditions were 3V voltage and a current density of 15mA / cm 2 The test time is 500 hours. After the test, there is no obvious peeling of the coating and no corrosion occurs on the surface.

[0068] The prepared anode exhibits excellent corrosion resistance and stability, and the conductivity of the coating remains stable. Compared with existing DSA electrodes, its cost is reduced by 30% and its service life is extended by 2 times.

[0069] Example 4: Industrial cleaning water recovery and reuse Lithium absorption and cleaning operations During the lithium absorption process, 0.5 L of desalted water was used to clean the lithium absorption channel after each lithium absorption, and the lithium ion concentration in the cleaning solution was 50 mg / L.

[0070] Wash water recovery The collected cleaning wastewater is passed through a filtration device to remove solid impurities. The lithium ions in the cleaning solution are then concentrated through an electrodialysis device, and the lithium concentration is increased to 200 mg / L.

[0071] Reuse The concentrated cleaning water is reintroduced into the lithium absorption channel and used as circulating fluid, and no additional desalted water needs to be added.

[0072] The process water consumption is reduced by 40%, and the lithium resource recovery rate in the cleaning water is increased to 95%. Compared with the traditional direct wastewater discharge mode, the environmental protection treatment cost is effectively reduced.

[0073] Example 5: Efficient lithium absorption and large-scale lithium release of salt lake brine Raw material selection and pretreatment The brine extracted from the salt lake has a lithium concentration of 500 mg / L. After filtration, it directly enters the lithium absorption equipment, and the pore size of the filter membrane is 15 μm.

[0074] Lithium absorption and release equipment parameters The lithium absorption flow rate was set at 2 L / min, the operating voltage was 3.2 V, and the current density was 18 mA / cm 2 , the duration is 80 minutes.

[0075] The lithium discharge receiving solution is 0.4% lithium hydroxide solution, the lithium discharge flow rate is 1.5L / min, the working voltage is increased to 4.8V, and the time is 50 minutes.

[0076] Running tests at scale The industrial equipment was operated continuously for 48 hours, during which lithium absorption and release were cycled alternately, and a total of 50m3 of brine was treated. 3 .

[0077] The output of lithium hydroxide solution reached 400L with a concentration of 0.9%. The equipment operated stably without electrode damage or performance degradation. Compared with the existing intermittent production process, the processing efficiency was increased by about 30%, meeting the needs of large-scale production.

[0078] Comparative Example 1: Traditional adsorption method for lithium extraction Raw material handling Salt lake brine with a lithium concentration of 250 mg / L was used to filter impurities through a filter membrane with a pore size of 10 μm, which is the same as in Example 1.

[0079] Adsorption process The lithium ion is enriched by ion adsorption method, and the adsorbent is lithium-containing selective adsorption resin. The filtered brine is passed into the adsorption tower at a flow rate of 0.8L / min, the adsorption time is 3 hours, and the drainage after adsorption is directly discharged.

[0080] Desorption process The saturated resin was desorbed using 0.2M HCl solution for 2 hours. The resulting solution contained high concentrations of lithium ions and impurities (such as sodium, potassium, calcium, etc.). The desorbed solution was subjected to secondary precipitation, and sodium hydroxide was added to precipitate some impurities. The resulting liquid was used for subsequent lithium extraction.

[0081] Subsequent processing The desorption liquid is evaporated and concentrated to a lithium concentration of 0.5%, and then sodium hydroxide is added to adjust to alkalinity, and a lithium hydroxide solution is generated by reaction. After the reaction is completed, the lithium hydroxide solution is filtered to obtain the lithium hydroxide solution.

[0082] Comparative Example 2: Single-stage lithium absorption process Primary lithium absorption Oilfield wastewater with a lithium concentration of 300 mg / L was used, filtered through a 20 μm pore size filter membrane, and then directly sent to the single-stage lithium absorption channel. The working voltage was set to 3 V and the current density was 15 mA / cm 2 The wastewater flows through the lithium absorption channel at a flow rate of 2 L / min, and the lithium absorption time is 60 minutes.

[0083] Tail liquid treatment The tail liquid after lithium absorption is directly discharged without multi-stage series connection or tail liquid reuse.

[0084] Lithium discharge operation The active electrode after absorbing lithium was subjected to lithium discharge operation, the receiving solution for lithium discharge was 0.3% lithium hydroxide solution, the flow rate was set to 1.2 L / min, the working voltage for lithium discharge was set to 4 V, and the lithium discharge time was 40 minutes.

[0085] The following is a comparative example of the design. Based on the aforementioned embodiment, the process of the comparative example is described in detail by adjusting parameters or adopting solutions in the prior art.

[0086] Comparative Example 1: Traditional adsorption method for lithium extraction Raw material handling Salt lake brine with a lithium concentration of 250 mg / L was used to filter impurities through a filter membrane with a pore size of 10 μm, which is the same as in Example 1.

[0087] Adsorption process The lithium ion is enriched by ion adsorption method, and the adsorbent is lithium-containing selective adsorption resin. The filtered brine is passed into the adsorption tower at a flow rate of 0.8L / min, the adsorption time is 3 hours, and the drainage after adsorption is directly discharged.

[0088] Desorption process The saturated resin was desorbed using 0.2M HCl solution for 2 hours. The resulting solution contained high concentrations of lithium ions and impurities (such as sodium, potassium, calcium, etc.). The desorbed solution was subjected to secondary precipitation, and sodium hydroxide was added to precipitate some impurities. The resulting liquid was used for subsequent lithium extraction.

[0089] Subsequent processing The desorption liquid is evaporated and concentrated to a lithium concentration of 0.5%, and then sodium hydroxide is added to adjust to alkalinity, and a lithium hydroxide solution is generated by reaction. After the reaction is completed, the lithium hydroxide solution is filtered to obtain the lithium hydroxide solution.

[0090] Comparative Example 2: Single-stage lithium absorption process Primary lithium absorption Oilfield wastewater with a lithium concentration of 300 mg / L was used, filtered through a 20 μm pore size filter membrane, and then directly sent to the single-stage lithium absorption channel. The working voltage was set to 3 V and the current density was 15 mA / cm 2 The wastewater flows through the lithium absorption channel at a flow rate of 2 L / min, and the lithium absorption time is 60 minutes.

[0091] Tail liquid treatment The tail liquid after lithium absorption is directly discharged without multi-stage series connection or tail liquid reuse.

[0092] Lithium discharge operation The active electrode after absorbing lithium was subjected to lithium discharge operation, the receiving solution for lithium discharge was 0.3% lithium hydroxide solution, the flow rate was set to 1.2 L / min, the working voltage for lithium discharge was set to 4 V, and the lithium discharge time was 40 minutes.

[0093] Comparative Example 3: Application of Traditional DSA Electrode Substrate treatment A titanium substrate was used as the anode, and the surface was directly coated with a ruthenium oxide-iridium oxide coating (DSA coating) without being treated. The coating thickness was about 30 μm.

[0094] Coating process The coating is sprayed, and then heat treated at 400°C for 1 hour. After the heat treatment, the coating is cooled naturally to obtain the DSA anode directly.

[0095] Electrochemical testing The prepared DSA electrode was placed in simulated lithium-containing brine, the operating voltage was set to 3 V, and the current density was set to 10 mA / cm 2 , continuous testing for 500 hours.

[0096] Comparative Example 4: Direct discharge of cleaning water Lithium absorption and cleaning operations The lithium absorption operation was the same as that in Example 4. After each lithium absorption, 0.5 L of desalted water was used to clean the lithium absorption channel, and the cleaning water was directly discharged without being recycled.

[0097] Wastewater treatment The cleaning wastewater is discharged directly into the wastewater treatment system for centralized treatment without being filtered or concentrated. During the wastewater treatment process, the lithium-containing wastewater is chemically precipitated, and the waste liquid is discharged after being filtered to remove impurities.

[0098] Comparative Example 5: Lithium Extraction Process Relying on Concentration and Evaporation (Corresponding to Example 5) Raw material selection and pretreatment Salt lake brine with a lithium concentration of 500 mg / L was used and filtered through a 15 μm pore size filter membrane to remove large particle impurities.

[0099] Evaporation Concentration The brine is directly fed into the evaporation equipment and evaporated at 80°C to concentrate the brine to a lithium concentration of about 2%. Anti-scaling agents are used during the evaporation process to reduce equipment scaling problems.

[0100] Lithium extraction Calcium hydroxide is added to the concentrated solution to carry out a precipitation reaction to generate lithium hydroxide precipitate, which is then filtered and separated, and the filtrate is further evaporated and concentrated to obtain a lithium hydroxide solution with a higher concentration.

[0101] Subsequent processing The filter residue and precipitate are processed through the solid waste treatment system, and the concentrated liquid is stored for future use.

[0102] Experiment 1: Comparative test of lithium extraction efficiency Experimental description: Experimental steps: Experimental materials: Salt lake brine: lithium ion concentration is 250 mg / L, and it also contains impurity ions such as sodium, magnesium, and calcium, which are 1000 mg / L, 300 mg / L, and 200 mg / L respectively.

[0103] Filter membrane: The pore size is 10μm, used for preliminary filtration of brine to remove large particles of impurities and suspended matter.

[0104] Embodiment 1 Equipment: includes an active electrode (nickel cobalt oxide) and an inert electrode (sandwich structure anode), a DC power supply and a flow channel system.

[0105] Comparative Example 1 Equipment: an adsorption tower containing a lithium ion selective adsorption resin (commercial adsorbent).

[0106] Experimental setup Example 1 Test: The filtered brine is passed into the lithium absorption channel of the electrochemical lithium extraction equipment at a flow rate of 1.5L / min. Lithium absorption conditions: voltage 3V, current density 15mA / cm 2After the lithium absorption was completed, the flow channel was cleaned with 0.5L of desalted water, and then the lithium was released with 0.2% lithium hydroxide solution for 50 minutes, the voltage was 4.5V, and the flow rate was 1L / min.

[0107] Comparative Example 1 Test: The filtered brine was passed into the adsorption tower at a flow rate of 0.8 L / min for 3 hours. After saturation, 0.2 M HCl solution was used for desorption at a flow rate of 1 L / min for 2 hours. After the desorbed solution was concentrated to a lithium concentration of 0.5% by heating and evaporation, calcium hydroxide was added to react and generate a lithium hydroxide solution.

[0108] Data Records: The amount of lithium ions recovered during the lithium absorption and desorption process was recorded.

[0109] Determine the energy consumption in each process step, including electrolysis, heating and pumping.

[0110] Calculate the total time from raw material processing to the final production of lithium hydroxide solution.

[0111] Table 1: Comparative test data of lithium extraction efficiency in Experiment 1 Through comparison, it can be clearly seen in this experiment that the electrochemical lithium extraction process of the present invention has achieved a significant improvement in process efficiency. Example 1 adopts an electric field-driven selective adsorption and release process, and lithium ions can quickly migrate to the active electrode surface, avoiding interference from impurity ions. In the lithium release stage, lithium ions are efficiently released under the condition of polarity reversal, and the whole process is completed in a relatively short time. In contrast, Comparative Example 1 relies on traditional adsorption resins, the adsorption process takes longer, and the competitive effect of impurity ions on lithium ion adsorption is obvious, resulting in a low lithium recovery rate.

[0112] From a mechanistic point of view, the present invention is based on the small hydration radius of lithium ions (0.38nm), which is highly selective for lithium ions under electrochemical conditions. The pore size and charge characteristics of the active electrode surface provide favorable conditions for the migration and enrichment of lithium ions. In contrast, in Comparative Example 1, since the adsorption mechanism of the adsorption resin relies on ion exchange, impurity ions (such as Na + , Ca 2+ ) directly reduces the lithium selectivity, and the desorption process requires a strong acid environment, which adds additional energy consumption and operating steps.

[0113] In addition, the energy consumption advantage of the present invention is also very significant. The electrolysis energy consumption in the electrochemical process is only 3.2 kWh, while in Comparative Example 1, an additional high-temperature evaporation step is required, and the overall energy consumption is as high as 8.7 kWh. This difference is mainly due to the great simplification of the process flow of the present invention, which does not rely on high-temperature operation and avoids multi-step concentration processes.

[0114] The experiment also verified the comparison results of the overall operation time. The electrochemical lithium extraction method of the present invention completes the entire process from brine to lithium hydroxide solution within two hours, while Comparative Example 1 takes nearly 5 hours. This further shows that the present invention not only significantly improves efficiency, but also simplifies the process path, making industrial application more practical.

[0115] Experiment 2: Comparative test of tail liquid utilization Experimental description: Experimental steps: The experimental materials were prepared using oilfield wastewater as samples, with an initial lithium ion concentration of 300 mg / L and impurity ion (such as sodium, magnesium, and calcium) concentrations of 1200 mg / L, 400 mg / L, and 250 mg / L, respectively. The wastewater was filtered through a 20 μm pore size filter membrane to remove suspended impurities before use.

[0116] The equipment of Example 2 and Comparative Example 2 are a multi-stage series lithium absorption system and a single-stage lithium absorption system, respectively, and are both equipped with an active electrode (nickel-cobalt oxide) and an inert electrode (iron-based sandwich anode).

[0117] Testing Process Example 2: Multi-stage series lithium absorption process The filtered wastewater enters the first lithium absorption channel at a flow rate of 2L / min. The operating voltage is 3V and the current density is set to 12mA / cm 2 The lithium absorption time is 60 minutes. The tail liquid enters the second lithium absorption channel from the outlet of the first lithium absorption channel. The lithium absorption conditions are the same and the lithium absorption time is 50 minutes. After the lithium absorption is completed, each lithium absorption channel is cleaned with 0.5L desalted water, and the cleaning water is recycled for subsequent lithium absorption cycles.

[0118] Comparative Example 2: Single-stage lithium absorption process The filtered wastewater directly enters the single-stage lithium absorption channel at a flow rate of 2L / min, with an operating voltage of 3V and a current density of 15mA / cm 2 The lithium absorption time is 60 minutes. The tail liquid is directly discharged without multi-stage treatment or recycling. The lithium absorption channel is cleaned with 0.5L desalted water, and the cleaning water is also discharged.

[0119] Data Recording Measure the lithium concentration of the tail liquid after each stage of lithium absorption, and record the residual lithium amount in the tail liquid.

[0120] Calculate the lithium recovery rate and tail liquid resource utilization rate of each process.

[0121] The lithium concentration of the wash water is measured to evaluate the lithium recovery potential in the tail liquid.

[0122] Table 2: Comparative test data of tail liquid utilization in Experiment 2 The experimental results show that the recovery efficiency of the multi-stage series lithium absorption process is much higher than that of the single-stage lithium absorption process. During the first-stage lithium absorption, the lithium concentration dropped from 300 mg / L to 100 mg / L, and then entered the second-stage lithium absorption channel to further drop to 25 mg / L, and the lithium in the tail liquid was basically completely recovered. This graded treatment method effectively improves the migration efficiency of lithium ions by gradually reducing the gradient concentration difference, while achieving deep utilization of the tail liquid. In the single-stage lithium absorption process, the lithium concentration of the tail liquid is still high, and resources are seriously wasted. The high lithium residue in the tail liquid further shows that it is difficult to completely separate lithium ions by single-stage lithium absorption.

[0123] From a mechanistic point of view, the multi-stage lithium absorption process reduces the lithium concentration after each stage of lithium absorption, providing a more significant concentration gradient for the next stage of lithium absorption. This concentration difference-driven ion migration mechanism is particularly critical in electrochemical systems, and the selective adsorption of lithium ions by active electrodes further enhances the separation efficiency. However, a single-stage lithium absorption system can only process part of the lithium ions. Due to fixed electrochemical conditions, the ion migration rate is difficult to maintain, resulting in insufficient resource utilization.

[0124] The lithium concentration of the cleaning water in the multi-stage lithium absorption system is significantly lower than that in the single-stage system, which shows that the multi-stage series connection not only recovers more lithium resources, but also reduces the ineffective loss of lithium. In the single-stage system, the higher lithium concentration of the cleaning water further amplifies the problem of resource waste.

[0125] Experiment 3: Inert anode performance comparison test Experimental description: Experimental steps: Experimental material preparation Anode sample: The sandwich structure inert anode prepared in Example 3 has an aluminum substrate and a coating layer of a PVDF / carbon black / graphite composite coating with a thickness of 20 μm.

[0126] The conventional DSA anode prepared in Comparative Example 3 has a titanium substrate and a coating layer of a mixed coating of ruthenium oxide and iridium oxide with a thickness of 30 μm.

[0127] Electrolyte: Simulated salt lake brine, with a lithium concentration of 250 mg / L, sodium ions of 1000 mg / L, magnesium ions of 200 mg / L, calcium ions of 100 mg / L, and a pH of 7.

[0128] Test conditions: Electrolysis conditions: working voltage 3V, current density 15mA / cm 2 The electrolysis time was 500 hours and the electrolysis temperature was maintained at 25±2℃.

[0129] Anode size: 50mm×50mm. Each set of anodes is fixed in the test tank to form an electrolysis circuit with the counter electrode (stainless steel).

[0130] Regular sampling: Sample the electrolyte every 100 hours to measure the lithium ion concentration and impurity ion content, and record the stability changes of the electrolysis voltage.

[0131] Performance Testing and Data Logging Coating peeling: Observe the coating structure changes through the scanning electron microscope (SEM) on the anode surface and record whether coating peeling or holes occur.

[0132] Corrosion resistance test: Electrochemical impedance spectroscopy (EIS) was used to test the corrosion current density of the anode, and the test frequency range was 0.1Hz-100kHz.

[0133] Electrochemical stability: Monitor the changes in anode potential and current density during electrolysis to evaluate its stability.

[0134] Table 3: Comparative data of inert anode performance in Experiment 3 Test items Example 3 (Sandwich Anode) Comparative Example 3 (DSA anode) Initial coating thickness (μm) 20 30 Coating peeling area (%) 0.5 12 <![CDATA[Corrosion current density (μA / cm 2 )]]> 0.12 0.95 Electrolysis voltage fluctuation (V) ±0.05 ±0.2 Electrolysis stability time (h) >500 320 Anode life estimation (h) 5500 1500 From the experimental performance, it can be seen that the sandwich structure anode of the present invention shows excellent stability during long-term electrolysis. After the anode coating is treated with a high-temperature and high-pressure press coating process, its adhesion is significantly enhanced. After 500 hours of continuous electrolysis, the coating peeling area is only 0.5%. In contrast, the traditional DSA anode in the comparative example has a loose combination of coating and substrate, and the coating peeling rate is as high as 12% in a corrosive electrolysis environment. This difference clearly shows that the sandwich structure design used in the present invention effectively improves the mechanical strength and corrosion resistance of the coating.

[0135] Mechanistically, the sandwich-structured conductive coating is composed of a composite material of PVDF and carbon black, which not only ensures the stability of the conductive network, but also provides excellent chemical resistance. The density of the coating is the key to corrosion resistance. It reduces the direct contact between the electrolyte and the substrate, reduces the electrochemical reaction rate, and thus effectively prolongs the life of the anode. The comparative anode relies on traditional iridium oxide and ruthenium oxide coatings, which are prone to microcrack propagation under high current density conditions, resulting in rapid failure of the coating.

[0136] The electrochemical stability test further showed that the potential fluctuation of the anode of Example 3 during electrolysis was only ±0.05V, while the fluctuation of the anode of the comparative example reached ±0.2V. This obvious difference shows that the conductive network of the coating is more stable in the design of the present invention and can maintain a stable current output for a long time. The anode life prediction results further support this point: the life of the sandwich anode exceeds 5000 hours, which is more than 3 times that of the traditional DSA anode.

[0137] The test results of corrosion current density clearly show the difference in the corrosion resistance of the anode. The corrosion current density of the anode of the present invention is as low as 0.12 μA / cm 2 , which is almost 1 / 8 of the control anode. This indicator reflects the effective protection of the coating on the substrate, and further illustrates the rationality of the selection of coating materials and substrates.

[0138] Experiment 4: Comparative test of cleaning water recovery and discharge Experimental description: Experimental steps: The experimental materials prepared used salt lake brine as the experimental sample, with an initial lithium concentration of 250 mg / L, containing 1000 mg / L sodium ions, 300 mg / L magnesium ions, 150 mg / L calcium ions, and a pH value of 7.

[0139] The cleaning water is desalted water with a purity of ≥99.9%, and the amount used for each flow channel cleaning is 0.5L.

[0140] The equipment of Example 4 includes a cleaning water filtration and electrodialysis system, while the comparative example 4 is directly discharged without recovery equipment.

[0141] Testing Process Example 4: Washing water recovery process After each lithium absorption or release operation, 0.5L of desalted water is used to clean the flow channel. The cleaning wastewater passes through the filtration device to remove particulate impurities, and then enters the electrodialysis equipment to increase the lithium concentration in the cleaning water from 50mg / L to 200mg / L before reuse. The reused water directly enters the next round of lithium absorption or release operation, and the number of cleaning water cycles and recovery efficiency are recorded.

[0142] Comparative Example 4: Direct Discharge Process After each cleaning, the wastewater is directly discharged into the wastewater treatment pool without any recycling step. The total amount of wastewater and its lithium concentration are recorded, and the waste of lithium resources in the wastewater is counted.

[0143] Data Recording After each recovery or discharge of the wash water, the lithium concentration of the wash water and the total wastewater discharge were measured.

[0144] Record the cumulative number of times the cleaning water is reused and the total amount of lithium ions lost during the recycling process.

[0145] The lithium recovery rate, washing water usage and wastewater discharge of the two processes were compared.

[0146] Table 4: Comparative test data of cleaning water recovery and discharge in Experiment 4 Test items Example 4 (Washing Water Recovery) Comparative Example 4 (direct discharge) Washing water usage (L) 2 2 Reuse times 4 - Wastewater discharge (L) 0.5 2 Wastewater lithium concentration (mg / L) 20 45 Total lithium loss (mg) 15 90 Lithium recovery rate (%) 97.5 84 Resource utilization (%) 92 41 The experimental results clearly show the significant difference between washing water recovery and direct discharge. Example 4 recycles the washing water through filtration and electrodialysis equipment, which significantly reduces the use of washing water and produces only a small amount of wastewater. The direct discharge method of comparative example 4 not only has a large amount of wastewater discharge, but also has an extremely high loss rate of lithium resources in the wastewater, resulting in low overall resource utilization. This gap is very obvious, and it also highlights the technical advantages of the washing water recovery process in water conservation and resource recovery.

[0147] From a mechanism perspective, the electrodialysis device of the present invention utilizes the efficient separation and concentration capabilities of selective ion membranes for lithium ions. During the electrodialysis process, lithium ions rapidly migrate to the concentration chamber driven by the electric field, causing the lithium concentration in the cleaning water to increase rapidly, while most of the impurity ions are effectively blocked. This physical separation mechanism avoids the energy waste problem in traditional chemical precipitation or evaporation concentration processes. In contrast, in the direct discharge method, due to the lack of any recovery steps, lithium ions are lost with the wastewater, and impurity ions further reduce the possibility of resource recovery.

[0148] The cleaning water recovery process not only saves water consumption, but also reduces the pressure of wastewater treatment. Compared with the treatment method of direct discharge of cleaning water after one-time use in Comparative Example 4, the recycling process is more reasonable in terms of economy and environmental protection. The comparison of lithium concentration in wastewater also proves the effect of the recovery process again: the lithium concentration of wastewater in Example 4 is reduced to 20 mg / L, while that in Comparative Example 4 is as high as 45 mg / L. This comparison fundamentally verifies the key role of the electrodialysis system in the deep utilization of lithium resources.

[0149] In addition, this experiment highlights the importance of resource utilization. In Example 4, the lithium resource utilization rate exceeds 90%, which is much higher than 41% in the comparative example. This is particularly critical, showing the comprehensive advantages of the present invention in saving resources and reducing environmental burden. This efficient cleaning water circulation mechanism can not only reduce the operating costs of enterprises.

[0150] Experiment 5: Production efficiency comparison test Experimental description: Experimental steps: Experimental materials Preparation of brine raw materials: brine samples collected from salt lakes, with a lithium ion concentration of 500 mg / L, and also containing sodium ions 1500 mg / L, magnesium ions 400 mg / L, calcium ions 200 mg / L, and the pH value was adjusted to 7.2.

[0151] Embodiment 5 Equipment: An electrochemical lithium extraction system, including a lithium absorption channel and a lithium release channel, each equipped with an active electrode and a sandwich structure inert electrode.

[0152] Comparative Example 5 Equipment: Traditional evaporation concentration equipment, equipped with an evaporation tank and a steam heating system, and calcium hydroxide is used in the precipitation process.

[0153] Testing Process Embodiment 5: The brine directly enters the electrochemical lithium extraction system with a flow rate of 2L / min. The working voltage of the lithium absorption stage is 3.2V and the current density is 18mA / cm 2 , the lithium absorption time is 80 minutes; in the lithium release stage, 0.4% lithium hydroxide solution is used as the receiving solution, the voltage is 4.8V, and the lithium release time is 50 minutes. The whole process runs for 48 hours, and the efficiency, energy consumption and output in the process of lithium absorption and release are measured.

[0154] Comparative Example 5: The brine enters the evaporation equipment and is evaporated and concentrated at 80°C for 8 hours. After concentration, the lithium concentration is increased to 2%. Calcium hydroxide is added for precipitation reaction for 1 hour, and a crude lithium hydroxide solution is obtained after filtration. The crude solution is evaporated and concentrated again to a lithium concentration of 0.8%, and the total output and energy consumption are tested.

[0155] Data Recording Efficiency: Record the amount of brine processed and the output of lithium hydroxide solution obtained for each batch.

[0156] Energy consumption: Statistics of electrical energy or heat energy consumption at each stage.

[0157] Processing time: record the total process time from the entry of raw materials to the final lithium hydroxide solution.

[0158] Table 5: Comparative test data of production efficiency in Experiment 5 Test items Example 5 (Electrochemical Lithium Extraction) Comparative Example 5 (Evaporation Concentration) Brine treatment capacity (L) 50 50 Lithium absorption time (min) 80 - Lithium discharge time (min) 50 - Evaporation time (min) - 480 Reaction / precipitation time (min) - 60 Lithium hydroxide solution output (L) 400 390 Total energy consumption (kWh) 12.5 36.8 Total process time (h) 48 57 The experimental results very intuitively show the advantages of the electrochemical lithium extraction process in production efficiency. In Example 5, through the efficient electrochemical separation of lithium absorption and release stages, the whole process operation can be completed only at room temperature, and the total output of lithium hydroxide solution reaches 400L, and the energy consumption is only 12.5kWh. Comparative Example 5 relies on traditional evaporation and concentration technology, which not only requires a long heating process, but also consumes up to 36.8kWh of energy, has a complex process and higher equipment requirements. This comparison highlights the technical value of the process of the present invention in energy conservation and emission reduction.

[0159] The electrochemical lithium extraction process achieves the selective migration and enrichment of lithium ions through electric field drive. Its essence is to utilize the low hydration radius of lithium ions and the adsorption characteristics of active electrodes to ensure efficient separation of lithium ions. Especially in the lithium release stage, lithium ions are released from the active electrode to the lithium hydroxide receiving solution by polarity reversal, avoiding the interference of impurity ions in the traditional precipitation reaction. In contrast, the evaporation concentration in Comparative Example 5 is not only energy-intensive, but also relies on multiple conversion processes, which increases complexity and cost.

[0160] The whole process of Example 5 was completed within 48 hours, while the evaporation concentration and precipitation process of Comparative Example 5 took more than 57 hours. This difference is not only reflected in production efficiency, but also reflects the reduction of equipment occupancy time. The shorter process cycle directly improves the processing capacity of the system and is suitable for continuous production on an industrial scale. Through this optimization, the present invention can not only improve the efficiency of lithium resource utilization, but also reduce equipment investment and operating costs.

[0161] In salt lake brine containing high concentrations of impurity ions, the electrochemical lithium extraction process showed excellent selectivity, while the precipitation reaction process in Comparative Example 5 was easily interfered by magnesium ions and calcium ions, resulting in a decrease in the purity of the precipitate.

[0162] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for directly preparing lithium hydroxide by electrochemical method, characterized in that: The following steps are involved: Provide lithium-containing brine and filter to remove solid particles and suspended matter; Passing the filtered lithium-containing brine into a lithium absorption channel of an electrochemical lithium extraction device, wherein the lithium absorption channel includes an active electrode and an inert electrode, wherein the active electrode is connected to the negative electrode of a DC power supply, and the inert electrode is connected to the positive electrode of the DC power supply; Under the action of electric field, lithium ions are enriched through active electrodes in lithium-containing brine; After lithium absorption is completed, the lithium absorption channel is flushed with desalted water; Passing a lithium-discharging receiving solution into a lithium-discharging flow channel, wherein the lithium-discharging flow channel includes an active electrode and an inert electrode, wherein the active electrode is connected to the positive electrode of a DC power supply, and the inert electrode is connected to the negative electrode of the DC power supply, and lithium ions are released from the active electrode to the lithium-discharging receiving solution; After the lithium discharge is completed, the lithium discharge channel is cleaned with desalted water and the cleaning water is recycled.

2. The method for directly preparing lithium hydroxide by electrochemical method according to claim 1, characterized in that: In the lithium absorption step, the operating voltage in the lithium absorption channel is 2.5-3.5V, and the current density is 10-20mA / cm 2 The lithium absorption time is 60-90 minutes.

3. The method for directly preparing lithium hydroxide by electrochemical method according to claim 1, characterized in that: In the lithium discharge step, the operating voltage in the lithium discharge flow channel is 3.5-5V, and the current density is 20-30mA / cm 2 The lithium release time is 40-60 minutes.

4. The method for directly preparing lithium hydroxide by electrochemical method according to claim 1, characterized in that: The lithium receiving solution is a lithium hydroxide solution with a concentration of 0.1%-0.5%.

5. The method for directly preparing lithium hydroxide by electrochemical method according to claim 1, characterized in that: The lithium-containing tail liquid generated after the lithium absorption step is connected in series through multiple lithium absorption channels to absorb lithium for the second time, and the lithium concentration is reduced by 10%-20% after each stage of lithium absorption.

6. A method for preparing an inert anode, according to the method for directly preparing lithium hydroxide by electrochemical method according to any one of claims 1 to 5, characterized in that: The following steps are involved: Providing a current collector, wherein the current collector is made of iron or aluminum; Pre-treating the surface of the current collector, wherein the pre-treatment includes sandblasting or chemical etching, and the surface roughness is Ra1.0-2.0 μm; Prepare conductive coating materials by mixing thermoplastic conductive polymers with conductive fillers, wherein the conductive fillers are carbon black, graphite or carbon nanotubes, and the conductive fillers account for 5%-20%; Applying the conductive coating material to both sides of the current collector by heating and pressing, the heating temperature is 180-250° C., and the pressure is 20-50 MPa; After coating, cooling and surface treatment are performed to obtain an inert anode.

7. The method for preparing an inert anode according to claim 6, characterized in that: The conductive polymer is one or more of PVDF, PTFE, PE or PP.

8. The method for preparing an inert anode according to claim 6, characterized in that: The thickness of the conductive coating is 10-50 μm.

9. The method for preparing an inert anode according to claim 6, characterized in that: In the pretreatment step, the current collector is sandblasted or chemically etched and then cleaned and dried.

10. The method for preparing an inert anode according to claim 6, characterized in that: After the cooling step, the surface of the inert anode is polished to a surface roughness of Ra 0.5-1.5 μm.

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