A multi-stage membrane separation coupled catalytic enhanced pulse electrochemical regeneration lithium ion battery electrolyte closed-loop recovery system and method

Abstract

The application discloses a kind of multistage membrane separation coupling catalysis enhanced pulse electrochemical regeneration lithium ion battery electrolyte closed loop recovery system, the system includes pretreatment unit, impurity targeted removal module, dynamic cleaning integrated membrane separation module, pulse electrochemical regeneration device, circulation feedback module and intelligent control module;The pretreatment unit, impurity targeted removal module, dynamic cleaning integrated membrane separation module, pulse electrochemical regeneration device and circulation feedback module are sequentially connected by connecting pipeline;The intelligent control module is respectively controlled with sensor, pump and valve in pretreatment unit, impurity targeted removal module, dynamic cleaning integrated membrane separation module and pulse electrochemical regeneration device by electric connection.It is realized that heavy metal ions, fluoride and high molecular residue are synchronously removed by depth pretreatment module, without additional chemical reagent, compared with traditional wet recovery, and carbon emission is reduced by more than 85%.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery resource recycling technology, specifically relating to a closed-loop recycling system and method for lithium-ion battery electrolyte using multi-stage membrane separation coupled with catalytic enhancement and pulse electrochemical regeneration. Background Technology

[0002] Lithium-ion battery electrolytes consist of organic solvents (such as ethylene carbonate EC, dimethyl carbonate DMC, and ethyl methyl carbonate EMC), lithium salts (mainly lithium hexafluorophosphate LiPF6), and functional additives (such as vinylene carbonate VC and fluoroethylene carbonate FEC). Improper disposal after disposal can lead to soil and water pollution due to fluorides (HF, LiF), and also waste of lithium resources. While existing electrolyte recycling technologies have made some progress, significant shortcomings remain in terms of industrial applicability, thoroughness of impurity removal, regeneration efficiency, and customized reuse. 1. Incomplete removal of impurities during pretreatment: Traditional pretreatment only removes solid impurities through 5-10μm precision filtration and reduces water content through dehydration membranes, but it cannot specifically remove residual Co in the electrolyte. 2+ Ni 2+ Heavy metal ions (typically 0.3-0.8 ppm) and free HF (3-6 ppm) are present. These impurities easily adhere to the surface of the membrane module, forming a fouling layer, which leads to an accelerated rate of membrane flux decay (over 25% decay rate after 1000 hours). They also affect the purity of lithium salt regeneration, making it difficult to maintain the purity of LiPF6 stably above 99.8%. 2. Insufficient scalability of membrane separation systems: Existing multi-stage membrane separation systems mostly adopt a pure series structure of "microfiltration-ultrafiltration-nanofiltration-pervaporization". When the throughput is increased to more than 50L / h, problems such as uneven load on single-stage membranes and large local flow rate fluctuations are likely to occur, resulting in a decrease in separation efficiency (such as organic solvent recovery rate dropping from 95% to below 88%). Moreover, the maintenance method relies on "offline backwashing every 8 hours", resulting in long downtime and difficulty in meeting the needs of continuous industrial production. 3. The contradiction between electrochemical regeneration efficiency and energy consumption is prominent: Traditional pulse electrochemical regeneration devices adopt a fixed electrode spacing design (usually 10-15mm), resulting in uneven oxygen distribution in the regeneration chamber and a lack of catalyst assistance. This leads to a high activation energy (about 80kJ / mol) for the recombination reaction of LiF and POF3, requiring more than 60 minutes for LiPF6 regeneration. Although the energy consumption is lower than that of DC electrolysis, there is still 15-20% room for optimization. 4. Lack of customization and feedback mechanism for electrolyte preparation and reuse: Existing preparation methods mostly adopt a fixed ratio of "90% solvent - 10% lithium salt - 1% additive", which cannot adapt to the differentiated needs of NCM batteries (requiring EC:DMC:EMC=3:5:2, LiPF6 concentration 1.2mol / L) and LFP batteries (requiring EC:DMC=1:1, LiPF6 concentration 1.0mol / L). In addition, there is no rapid verification process for the performance of regenerated electrolytes, making it difficult to guarantee the cycle life of the reused batteries (e.g., the capacity retention rate after 1000 cycles is likely to be less than 90%). Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a closed-loop recycling system and method for lithium-ion battery electrolyte with multi-stage membrane separation coupled with catalytic enhancement and pulse electrochemical regeneration. This invention achieves simultaneous removal of heavy metal ions, fluorides and polymer residues through a deep pretreatment module, without the need for additional chemical reagents, and reduces carbon emissions by more than 85% compared with traditional wet recycling.

[0004] To achieve the above-mentioned objectives, the technical solution provided in this application is as follows: A closed-loop recovery system for lithium-ion battery electrolyte, featuring multi-stage membrane separation coupled with catalytic enhancement and pulsed electrochemical regeneration, is disclosed. The system comprises a pretreatment unit, a targeted impurity removal module, a dynamically cleaned integrated membrane separation module, a pulsed electrochemical regeneration device, a circulation feedback module, and an intelligent control module. These components are sequentially connected via connecting pipes. The intelligent control module controls sensors, pumps, and valves within the pretreatment unit, targeted impurity removal module, dynamically cleaned integrated membrane separation module, and pulsed electrochemical regeneration device through electrical connections. The pretreatment unit includes a precision filter, a pH adjustment tank, and a dehydration membrane assembly; the impurity targeted removal module includes an adsorption fixed bed and a hydroxyapatite microsphere packed column. The dynamic cleaning integrated membrane separation module employs a parallel pretreatment membrane group, a dual-stage series nanofiltration membrane group, and a parallel pervaporation membrane group. These three groups are connected sequentially via pipelines. The parallel pretreatment membrane group includes microfiltration membranes and ultrafiltration membranes, with the microfiltration and ultrafiltration membranes connected together. Two sets of microfiltration membranes and two sets of ultrafiltration membranes are configured, with both sets connected in parallel. The dual-stage series nanofiltration membrane group includes two nanofiltration membranes connected in series. The parallel pervaporation membrane group includes two sets of silicone rubber composite membranes connected in parallel. The pulsed electrochemical regeneration device includes an anode chamber, a regeneration chamber, and a cathode chamber, with adjacent chambers separated by a perfluorosulfonic acid resin cation exchange membrane; The cyclic feedback module includes a solvent storage tank, a lithium salt storage tank, an additive mixing tank, an online concentration detector, and a micro battery testing subsystem.

[0005] Furthermore, the precision filter is made of PVDF, has a pore size of 5μm, a pH adjustment tank volume of 500L, and a dehydration membrane assembly made of silicone rubber composite membrane.

[0006] Furthermore, the adsorption bed is made of modified mesoporous SiO2@chitosan in series. The adsorption bed has a packing particle size of 50-80 μm and an adsorption capacity ≥15 mg / g. The hydroxyapatite microspheres in the packed column have a particle size of 20-30 μm and a porosity of 60-70%. The specific surface area of ​​the modified mesoporous SiO2@chitosan is 800-1000 m² / g, and the specific surface area of ​​the composite adsorption material is 800-1000 m² / g. The modified mesoporous SiO2@chitosan has a specific surface area of ​​800-1000 m² / g for Co. 2+ and Ni 2+ The adsorption rate is ≥99.5%; hydroxyapatite microspheres have an adsorption rate of ≥99.5% for F. - The removal rate is ≥98%, and the hydroxyapatite microspheres retain polymeric residues with a molecular weight >5000Da.

[0007] Furthermore, the microfiltration membrane in the pretreatment membrane assembly has a pore size of 0.2 μm and is made of PVDF. The ultrafiltration membrane in the pretreatment membrane assembly is a polyethersulfone ultrafiltration membrane with a molecular weight cutoff of 1000 Da.

[0008] Furthermore, the nanofiltration membrane in the dual-stage tandem nanofiltration membrane assembly is an aromatic polyamide nanofiltration membrane.

[0009] Furthermore, the dynamic cleaning integrated membrane separation module is also equipped with a dynamic cleaning subsystem, which includes a cleaning solution tank and a high-pressure pulse pump. The cleaning solution tank stores deionized water and dilute sulfuric acid. When the membrane pressure difference in the dynamic cleaning integrated membrane separation module is >0.3MPa, the microfiltration membrane and ultrafiltration membrane are cleaned with deionized water for 15 minutes, and the nanofiltration membrane is cleaned with dilute sulfuric acid for 10 minutes.

[0010] Furthermore, the pulsed electrochemical regeneration device adopts a three-chamber split structure, consisting of an anode chamber, a regeneration chamber, and a cathode chamber from left to right. Adjacent chambers are separated by a perfluorosulfonic acid resin cation exchange membrane, which allows lithium ions to pass selectively while preventing solvent molecules and anions from mixing.

[0011] A closed-loop recovery method for lithium-ion battery electrolyte using multi-stage membrane separation coupled with catalytic enhancement and pulsed electrochemical regeneration, the method specifically includes the following steps: S1, Pretreatment: Waste electrolyte is passed into a precision filter at a flow rate of 80L / h. The filtrate enters a pH adjustment tank, and lithium carbonate powder is added to the pH adjustment tank to adjust the pH value to 4.5-5.5. Then, the water content is reduced to below 0.1% by the dehydration membrane module to obtain the pretreated solution. S2, deep impurity removal: the pretreatment solution is introduced into the adsorption fixed bed at a flow rate of 2.7 L / min and stays in the adsorption fixed bed for 30 minutes, and then introduced into the microsphere packed column at a flow rate of 4 L / min and stays in the microsphere packed column for 20 minutes to obtain the deep purified solution; S3, series-parallel membrane separation: the deep purified liquid is passed into the parallel pretreatment membrane group to obtain the permeate, the permeate is passed into the two-stage series nanofiltration membrane group to obtain the retentate, the retentate is sent to the pulse electrochemical regeneration device, and the permeated organic solvent is purified by the parallel pervaporation membrane group and then stored; when the membrane pressure difference is >0.3MPa, the online dynamic cleaning integrated membrane separation module is started. S4, catalytically enhanced pulsed electrochemical regeneration: the retentate is first sent into the regeneration chamber of the pulsed electrochemical regeneration device, the electrode distance is adjusted, gradient aeration and catalytic stirrer are turned on, a pulse voltage of 2.5-3V, 600-700Hz, and 50% duty cycle is applied, and the reaction time is 45min to obtain LiPF6 regenerated solution. S5 features intelligent adaptation, adjustment, and feedback. Input the target battery type, and the cyclic feedback module delivers solvent, regenerated lithium salt, and additives to the mixing tank according to the matching formula and stirs them evenly. Take the mixture to assemble micro batteries for testing. If it meets the standards, it can be reused; if it does not meet the standards, the components are adjusted and the test is repeated until the reuse requirements are met.

[0012] Furthermore, when the LiPF6 concentration in the retentate is >1.2 mol / L, the electrode distance is adjusted to 15-20 mm; when the LiPF6 concentration is <0.8 mol / L, the electrode distance is adjusted to 5-10 mm.

[0013] Furthermore, the Co in the deep purification liquid in S2 2+ and Ni 2+ The content of F is <0.05ppm. - <0.8ppm.

[0014] Furthermore, the purity of the LiPF6 regenerated solution in S4 is greater than 99.9%.

[0015] Based on the above technical solutions, the lithium-ion battery electrolyte closed-loop recovery system and method of multi-stage membrane separation coupled with catalytic enhancement and pulsed electrochemical regeneration has achieved the following technical advantages through practical application: 1. The present invention discloses a closed-loop recycling method for lithium-ion battery electrolyte using multi-stage membrane separation coupled with catalytic enhancement and pulse electrochemical regeneration. This method achieves simultaneous removal of heavy metal ions, fluorides, and polymer residues through a deep pretreatment module, without the need for additional chemical reagents. Compared with traditional wet recycling, it reduces carbon emissions by more than 85%. The generated CaF2 precipitate can be periodically recycled for fluorochemicals, with no solid waste discharge, truly achieving "no secondary pollution".

[0016] 2. The present invention discloses a closed-loop recovery method for lithium-ion battery electrolyte using a multi-stage membrane separation coupled with catalytic enhancement and pulsed electrochemical regeneration. Through a series-parallel membrane structure, the throughput is increased to 80 L / h, which is 8 times that of the traditional series system. Online dynamic cleaning reduces the membrane flux decay rate to 15% / 1000h, which is 40% lower than the traditional system. The membrane module life is extended to more than 3500h, which is 75% higher than the traditional system, thus meeting the needs of continuous industrial production.

[0017] 3. The present invention discloses a closed-loop recycling method for lithium-ion battery electrolyte through multi-stage membrane separation coupled with catalytic enhancement and pulse electrochemical regeneration. Through the synergistic effect of variable electrode spacing, gradient aeration and nano-Ir catalyst, the regeneration time of LiPF6 is shortened to 45 min, which is 25% less than that of traditional pulse electrolysis. The regeneration purity reaches more than 99.9%, which is 0.1 percentage points higher than that of traditional systems. The energy consumption is reduced by 15% compared with traditional pulse electrolysis, and is only 51% of that of DC electrolysis.

[0018] 4. This invention can be adapted to the electrolyte requirements of different battery systems such as NCM and LFP. The NCM811 battery assembled with regenerated electrolyte has a capacity retention rate of ≥92% after 1000 cycles, and the LFP battery has a capacity retention rate of ≥94%. Through the micro battery performance feedback mechanism, the safety of reuse is ensured, the battery production cost is reduced by 20-25%, and the cost is improved by 5 percentage points compared with traditional recycling technology. Attached Figure Description

[0019] Figure 1 This is a system structure diagram of a closed-loop recovery system for lithium-ion battery electrolyte using a multi-stage membrane separation coupled with catalytic enhancement and pulsed electrochemical regeneration according to the present invention.

[0020] Figure 2 This is a structural diagram of the pulse electrochemical regeneration device in a closed-loop recovery system for lithium-ion battery electrolyte using a multi-stage membrane separation coupled with catalytic enhancement and pulse electrochemical regeneration according to the present invention.

[0021] Figure 3 This is a flowchart of the dynamic cleaning integrated membrane separation module in a closed-loop recycling system for lithium-ion battery electrolyte that utilizes multi-stage membrane separation coupled with catalytic enhancement and pulsed electrochemical regeneration, as described in this invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described below with reference to specific examples shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0023] Example 1: Overall Structure of a Closed-Loop Recycling System for Lithium-ion Battery Electrolyte The system is connected sequentially via corrosion-resistant PTFE pipes to a pretreatment unit, a deep pretreatment-targeted impurity removal module, a series-parallel collaborative-dynamic cleaning integrated membrane separation module, a variable electrode distance-gradient aeration-catalytic pulse electrochemical regeneration device, and an electrolyte component intelligent adaptive adjustment-circulation feedback module. It is also equipped with an intelligent control module electrically connected to each unit, such as… Figure 1 As shown, the specific structure and parameters of each unit are as follows: 1. Pretreatment unit: Composed of a precision filter 11 (5μm pore size, PVDF material, model MF-PVDF-5), a pH adjustment tank 12 (500L volume, 316L stainless steel material, built-in stirrer, speed 300r / min), and a dehydration membrane assembly 13 (silicone rubber composite membrane, model PV-01), used to remove solid impurities with a particle size >5μm, add lithium carbonate powder to adjust the pH of the electrolyte to 4.5-5.5, and reduce the water content to below 0.1%; 2. Deep Pretreatment - Targeted Impurity Removal Module: A modified mesoporous SiO2@chitosan composite adsorption fixed bed and a hydroxyapatite (HAP) microsphere packed column are connected in series. Adsorption fixed bed: filled with modified mesoporous SiO2@chitosan composite adsorbent material with a particle size of 50-80μm (specific surface area 800-1000m² / g, adsorption capacity ≥15mg / g), capturing Co through the chelation of amino (-NH2) and hydroxyl (-OH) groups on the material surface. 2+ Ni 2+ ; HAP packed column 21: packed with hydroxyapatite microspheres with a particle size of 20-30 μm (porosity 60-70%), through which Ca 2+ With F - ion exchange reaction (Ca 10 (PO4)6(OH)2+2F - →Ca 10 (PO4)6F2+2OH - It removes free HF while retaining high molecular weight degradation residues (such as phosphate ester polymers) with a molecular weight >5000Da. 3. Series-Parallel Collaborative Dynamic Cleaning Integrated Membrane Separation Module 31: Adopts a composite structure of "parallel pretreatment membrane module → two-stage series nanofiltration membrane module → parallel pervaporation membrane module". Each membrane module is equipped with a pressure sensor (range 0-1MPa, accuracy ±0.01MPa), a flow regulating valve, and an online dynamic cleaning subsystem. Parallel pretreatment membrane array: 2 microfiltration membranes (pore size 0.2μm, material PVDF, model MF-0.2-PVDF) and 2 ultrafiltration membranes (molecular weight cutoff 1000Da, material polyethersulfone, model UF-1000-PES) are connected in parallel, with a single membrane designed to process 40L / h and a total processing capacity ≥80L / h; Dual-stage tandem nanofiltration membrane module: Two nanofiltration membranes (molecular weight cutoff 200 Da, material aromatic polyamide, model NF-200-PA) are connected in series to retain lithium salt (LiPF6) and functional additives, with a rejection rate ≥99.9%; Parallel pervaporation membrane array: Two sets of pervaporation membranes (material: silicone rubber composite membrane, model: PV-EC / DMC) are connected in parallel, operating at 60℃, used to purify organic solvents that have permeated through nanofiltration membranes, with a solvent purity of ≥99.9% after purification; Online dynamic cleaning subsystem: includes a cleaning solution storage tank (stores deionized water or 0.05mol / L dilute sulfuric acid), a high-pressure pulse pump (pressure 0.4MPa, model P-04) and a dedicated cleaning interface. The trigger condition is that the pressure difference between the inlet and outlet of the membrane module is >0.3MPa. The cleaning time is: 15min for microfiltration / ultrafiltration membranes (deionized water) and 10min for nanofiltration membranes (0.05mol / L dilute sulfuric acid). The pulsed electrochemical regeneration device adopts a three-chamber split structure, consisting of an anode chamber 41, a regeneration chamber 42, and a cathode chamber 43 from left to right (or along the fluid direction). Adjacent chambers are separated by a perfluorosulfonic acid resin cation exchange membrane (such as Nafion 117), which allows lithium ions (Li...) to pass through. + It allows selective passage while preventing solvent molecules and anions from mixing. The anode chamber 41 houses a ruthenium-iridium-titanium coated anode 44, electrically connected to the positive terminal of the pulse power supply. The regeneration chamber, the core reaction chamber, contains a foamed nickel cathode 45, electrically connected to the negative terminal of the pulse power supply. The bottom of the regeneration chamber features an annular aeration disc 46 of a gradient aeration system, with dotted aeration heads in the center for uniformly introducing gas (such as air or oxygen) into the chamber. The chamber also contains a titanium-based mesh stirrer with a surface-loaded nano-iridium (Ir) catalyst to enhance the reaction. The electrode distance between the cathode and anode can be dynamically adjusted via a screw adjustment mechanism (adjustment range 5-20 mm). An auxiliary cathode can be installed in the cathode chamber. In terms of connection, the lithium-containing concentrate (retentate) from the upstream membrane separation module is pumped into the regeneration chamber. A pulsed power supply applies a pulsed voltage with a specific frequency and duty cycle between the anode and cathode. Under the synergistic effect of the uniform reaction environment provided by the electric field, catalyst, and gradient aeration, degradation products (such as LiF and POF3) are efficiently regenerated into LiPF6. The regenerated liquid after the reaction is discharged from the regeneration chamber outlet and enters the subsequent circulation feedback module.

[0024] 4. Variable Gap Gradient Aeration-Catalytic Pulse Electrochemical Regeneration Device: This device employs a three-chamber split structure (anode chamber, regeneration chamber, cathode chamber), with adjacent chambers separated by a cation exchange membrane (made of perfluorosulfonic acid resin, model Nafion 117). The specific structure is as follows... Figure 2 As shown; The device employs a three-chamber design, with adjacent chambers separated by perfluorosulfonic acid resin cation exchange membranes (such as Nafion 117) to achieve selective ion migration. The specific structure of each chamber is as follows: Anode Chamber: (1) Internal Structure: The anode is mainly installed inside, and this electrode is preferably a ruthenium-iridium-titanium coated electrode. Connection: The anode is electrically connected to the positive terminal of the external pulse power supply. During electrolysis, the main reaction of water oxidation (oxygen evolution reaction) occurs here.

[0025] Regeneration Chamber (Core Reaction Chamber): (1) Internal Structure: Cathode: Typically uses a high specific surface area foamed nickel electrode, connected to the negative terminal of the pulse power supply. Gradient Aeration System: Consists of a bottom annular aeration disc and a central dotted aeration head, used to introduce gas (such as air or oxygen) into the reaction liquid, and to achieve uniform distribution of reactants in the chamber through a flow gradient. Catalytic Components: For example, a titanium-based mesh stirrer with surface-supported nano-iridium (Ir) catalyst, used to reduce the activation energy of the reaction and promote the regeneration of LiPF6. Electrode Spacing Adjustment Mechanism: Connects the cathode and anode, and can dynamically adjust the distance between the two electrodes (electrode spacing). Connection Relationship: Lithium-containing concentrate (retentate) from the preceding membrane separation module is pumped into this chamber. Under the synergistic effect of the pulse electric field, catalyst, and gradient aeration, the target regeneration reaction occurs.

[0026] Cathode chamber: (1) Internal structure: An auxiliary cathode may be installed to improve current distribution or manage side reactions. (2) Connection relationship: Adjacent to the regeneration chamber through an ion exchange membrane.

[0027] Structural Summary: The anode chamber, regeneration chamber, and cathode chamber are arranged sequentially from left to right (or according to the flow direction) and are physically separated by ion exchange membranes. A pulsed power supply connects the anode and cathode (located within the regeneration chamber), forming a circuit. The material (lithium-containing concentrate) enters the regeneration chamber through a pipeline, and the reacted regenerated solution is discharged from the regeneration chamber outlet.

[0028] Chamber labels: Anode chamber, Regeneration chamber, Cathode chamber.

[0029] Separating component: cation exchange membrane (located between the two chambers).

[0030] Electrodes: Anode (ruthenium-iridium-titanium coating), cathode (nickel foam).

[0031] Regeneration chamber components: gradient aeration system (bottom aeration disc / middle aeration head), catalytic agitator (loaded with nano-Ir), and pitch adjustment screw.

[0032] External connections: pulse power supply (+, -), feed pipe (from nanofiltration membrane), discharge pipe (to lithium salt storage tank), aeration pipeline.

[0033] II. Explanation of the connection relationships between the components of the cyclic feedback module This module is an intelligent closed-loop system of "storage-allocation-detection-feedback", and the components are connected in the following logical order: 1. Storage unit → Allocation unit The outlets of the solvent storage tank, lithium salt storage tank, and additive mixing tank are connected to a common mixing tank (or online static mixer) via independent metering pumps and pipelines.

[0034] 2. Allocation Unit → Online Detection Unit An online concentration detector is installed on the outlet pipe of the mixing tank to monitor key indicators such as the lithium salt concentration of the electrolyte after mixing in real time.

[0035] 3. Intelligent Control Core The intelligent control module (such as a PLC) is the brain of the system. It receives signals: receiving concentration data from the online concentration detector and performance data from the micro battery testing subsystem; and issues instructions: controlling the start, stop and flow of each metering pump according to the preset "battery type-recipe" database and feedback data, thereby accurately controlling the formula ratio.

[0036] 4. Performance Verification and Closed-Loop Feedback (1) Install an automatic sampling valve on the main pipeline downstream of the mixing tank.

[0037] (2) When performance verification is required, the intelligent control module commands the automatic sampling valve to open and send a small amount of the preparation solution into the micro battery testing subsystem.

[0038] (3) The subsystem quickly assembles and tests the button cell, and then feeds back the performance results (such as capacity retention rate) to the intelligent control module.

[0039] (4) Control logic: If the performance meets the standard, the electrolyte is transported to the reuse section; if it does not meet the standard, the intelligent control module automatically adjusts the formula and starts a new round of "mixing → detection → testing" cycle until the standard is met.

[0040] Summary of connection relationships: The material flow (storage tank → metering pump → mixing tank → detection / sampling) and the information flow (detector / testing subsystem → intelligent control module → metering pump) form a complete closed loop, realizing automatic, precise, and adaptive compounding of electrolyte.

[0041] Electrode assembly: The anode uses a ruthenium-iridium-titanium coated electrode (coating thickness 5-8μm, area 0.5m²), and the cathode uses a foamed nickel electrode (porosity ≥90%, area 0.5m²). The electrode support is equipped with a screw adjustment structure, and the electrode spacing adjustment range is 5-20mm. Gradient aeration system: It consists of a bottom annular aeration disc (0.5mm aperture) and three point aeration heads in the middle. The aeration flow rate gradually decreases from 0.6-0.8L / min at the bottom to 0.3-0.5L / min in the middle to ensure uniform oxygen concentration in the regeneration chamber (deviation <5%). Catalytic assembly: The regeneration chamber has an indoor titanium-based mesh stirrer (200 r / min rotation speed, 2 mm × 2 mm mesh size), and the surface of the stirrer is loaded with nano Ir catalyst (particle size 5-10 nm, loading 0.5-1.0 mg / cm²) to reduce the activation energy of the LiF and POF3 recombination reaction; Pulse power supply: Output voltage adjustable from 0-10V, frequency continuously adjustable from 50-1000Hz, duty cycle 30-70%, model PE-10; 5. Intelligent Adaptive Allocation and Circulation Feedback Module for Electrolyte Components: Includes a solvent storage tank (1000L), a lithium salt storage tank (500L), an additive mixing tank (100L, storing additives such as VC and FEC), an online concentration detector (accuracy ±0.01mol / L, model CD-01), and a micro-battery assembly-performance testing subsystem (model BT-01). This module is an integrated intelligent allocation and quality verification system. The components are connected via pipelines, pumps, valves, and a control system in the following logical sequence, forming a closed loop of detection-feedback-adjustment: Storage and transport unit: Solvent storage tanks, lithium salt storage tanks, and additive mixing tanks respectively store recovered organic solvents, regenerated LiPF6 solutions, and various functional additives.

[0042] Each storage tank outlet is connected to a common mixing tank via metering pumps and pipelines.

[0043] Online detection and intelligent allocation unit: An online concentration detector is installed on the outlet pipe of the mixing tank to monitor the concentration of key components (such as LiPF6) in the mixed solution in real time.

[0044] The intelligent control module receives the concentration signal from the detector and compares it with the built-in "battery type-component matching database". Based on the comparison results, it automatically controls the start / stop and flow rate of each metering pump to achieve precise dosing of each component.

[0045] Performance verification and feedback closed-loop unit: The micro battery testing subsystem is connected to the main pipeline after the mixing tank via an automatic sampling valve.

[0046] The system periodically or automatically collects a small amount of prepared electrolyte as instructed, sends it into the subsystem for rapid assembly into a button battery, and performs standard charge and discharge tests.

[0047] The performance data obtained from the test (such as initial coulombic efficiency and cycle capacity retention) is fed back to the intelligent control module in real time.

[0048] The intelligent control module compares the performance data with the reuse standards of the target battery: If the performance meets the standards, the instruction is to open the finished product output valve and deliver the electrolyte to the battery production line for reuse.

[0049] If the performance does not meet the standard, the formula parameters (such as the additive ratio) are fine-tuned according to the algorithm, and the system is instructed to repeat the cycle of formulation → detection → testing until the performance meets the standard.

[0050] Intelligent adaptive algorithm: Embedded "battery type-component matching database", after inputting the target battery type (such as NCM811, LFP), it automatically outputs the solvent ratio, lithium salt concentration and additive type (such as NCM811 corresponding to EC:DMC:EMC=3:5:2, LiPF6 1.2mol / L, VC 1%). Micro battery testing subsystem: It can quickly assemble CR2032 button batteries (positive electrode matches the target battery's positive electrode material, negative electrode is graphite, separator is Celgard 2400). The test parameters include the first charge-discharge efficiency (voltage range 2.7-4.3V, charge-discharge rate 0.1C) and the capacity retention rate after 50 cycles. The judgment criteria are first charge-discharge efficiency ≥90% and capacity retention rate after 50 cycles ≥95%.

[0051] 6. Intelligent control module: It adopts a PLC controller (Siemens S7-1200) to establish electrical connection with the sensors, pumps and valves of each unit to realize automatic control of flow rate, pressure, voltage and reaction time. It also has a fault alarm function (such as triggering an audible and visual alarm when the membrane pressure difference exceeds the standard or the purity of the regenerated liquid is not up to standard).

[0052] Example 2, System Working Principle 1. Principle of deep impurity targeted removal: The mesoporous structure of the modified mesoporous SiO2@chitosan composite adsorbent provides a high specific surface area, and the amino and hydroxyl groups in the chitosan molecule can react with Co. 2+ Ni 2+ It forms a stable chelate with an adsorption rate of ≥99.5%, ensuring that the content of heavy metal ions in the purified solution is <0.05ppm; Ca in hydroxyapatite microspheres 2+ With F in the electrolyte - Ion exchange occurs, generating stable CaF2 precipitate that adheres to the surface of the microspheres (which can be periodically recycled for use in fluorochemicals). At the same time, the porous structure of the microspheres traps polymer residues, achieving the simultaneous removal of "heavy metals-fluorides-residues". 2. Principle of series-parallel membrane separation and dynamic cleaning: Parallel pretreatment membrane modules achieve load equalization through flow distribution valves, avoiding overload of a single membrane module and increasing the overall throughput to 80L / h; dual-stage series nanofiltration membrane modules enhance the retention of lithium salts and additives, reducing the loss of target components; parallel pervaporation membrane modules shorten the organic solvent purification time and improve recovery efficiency. The online dynamic cleaning subsystem rapidly removes the impurity layer on the membrane surface through low-pressure pulse flushing (0.4MPa). Dilute sulfuric acid can dissolve the LiF precipitate attached to the nanofiltration membrane surface, effectively reducing the membrane flux decay rate (1000h decay rate ≤15%). 3. Principle of Catalytic Enhanced Pulse Electrochemical Regeneration: Variable electrode spacing design: The electrode spacing is dynamically adjusted according to the LiPF6 concentration in the regenerated solution (increased to 15-20 mm when the concentration is >1.2 mol / L to avoid local over-reaction; decreased to 5-10 mm when the concentration is <0.8 mol / L to increase the electric field strength). Gradient aeration: High-flow-rate aeration at the bottom ensures sufficient oxygen at the bottom of the regeneration chamber, while low-flow-rate aeration in the middle avoids local turbulence, providing a stable oxidation environment for the electrochemical repair (reduction of active groups) of additives (such as VC). Catalytic reaction: Titanium-based supported nano-Ir catalyst can reduce the activation energy of LiF and POF3 recombination to generate LiPF6 from 80kJ / mol to 55kJ / mol, accelerating the reaction rate. Combined with a pulsed electric field (frequency 500-800Hz, duty cycle 50%), electrode passivation is avoided, and rapid and low-consumption regeneration of LiPF6 is achieved. 4. Intelligent adaptation and performance feedback principle: Based on the "battery type-component matching database", the system automatically matches the electrolyte formula for different batteries. For example, the LFP battery corresponds to "EC:DMC=1:1, LiPF6 1.0mol / L, FEC 0.5%", without manual intervention. Supplementary explanation regarding the construction process of the "Battery Type-Component Matching Database" This "Battery Type-Component Matching Database" is not an existing publicly available database, but a dedicated database specifically constructed to achieve the precise and adaptive formulation of the regenerated electrolyte of this invention. Its construction process integrates battery chemistry theory, research on the characteristics of regenerated electrolytes, and extensive experimental verification. The specific steps are as follows: 1. Purpose and Data Foundation Objective: To establish a mapping relationship between different commercial lithium-ion battery systems (such as NCM811, NCM622, LFP, high-voltage LCO, etc.) and their corresponding optimal formulations when regenerating electrolytes using the system of this invention.

[0053] Basic data source: Publicly available or typical formulations of electrolytes for various types of new batteries (as an initial reference).

[0054] The basic physicochemical data (purity, moisture, metal impurity content, etc.) of the regenerated solvent, regenerated LiPF6, and recycled additives obtained by processing a large amount of similar waste battery electrolytes using the system of this invention.

[0055] Key parameters of the battery system itself, such as the positive and negative electrode materials and the operating voltage window.

[0056] 2. Database Construction and Optimization Methods The construction of the database is an iterative process of "theoretical presupposition - experimental verification - feedback optimization": a. Initial formulation library establishment: For each target battery type (such as LFP), based on its theoretical requirements and new electrolyte formulation, combined with the characteristics of regenerated components, an initial range of regenerated electrolyte formulations is preset (e.g., EC:DMC ratio fluctuates around 1:1, LiPF6 concentration is around 1.0 mol / L, and FEC additive is in the range of 0.5-2%).

[0057] b. Systematic performance testing and data generation: Using the system of this invention, multiple sets of regenerated electrolytes can be prepared according to different preset formula ratios.

[0058] For each electrolyte group, a simulated battery (such as a CR2032 button cell) of the target battery system is assembled strictly according to standard processes through an integrated "micro battery testing subsystem".

[0059] Standardized charge-discharge cycle tests, rate performance tests, and high-temperature storage tests are conducted on simulated batteries. Key recorded data include: initial charge-discharge efficiency, capacity retention rate after different number of cycles (e.g., 50, 100, and 500 cycles), and changes in internal resistance.

[0060] c. Performance Correlation Analysis and Optimal Value Determination: A large amount of test results (performance data) are correlated with corresponding formulation parameters, and mathematical models are fitted (e.g., using response surface methodology). With cycle life (e.g., capacity retention ≥ 90% after 500 cycles) and initial efficiency as primary objectives, one or more optimal formulation points for the regenerated electrolyte for this battery type are determined, and the allowable fluctuation range for each component is defined.

[0061] d. Data Entry and Validation: Enter the established correspondence between "battery type - optimal formulation - expected performance" into the database. To ensure reliability, each optimal formulation point must be validated through at least three parallel experimental batches, and the performance results must meet the statistical significance requirement.

[0062] 3. Database application and dynamic update logic Application: When the system is running, users or production lines only need to input the target battery type (such as "LFP"), and the intelligent control module will call the corresponding optimal formula in the database and automatically command each metering pump to feed the material in proportion.

[0063] Feedback optimization mechanism: Each test result from the "micro battery testing subsystem" is compared with the "performance expectations" in the database. If the properties of a batch of regenerated components experience a slight drift, causing the measured performance to continuously deviate from expectations, the system can trigger the database learning and update program, fine-tune the formula parameters within a preset fluctuation range, and incorporate effective adjustment experience into the database to achieve adaptive optimization of the system.

[0064] If the micro battery testing subsystem detects that the performance is not up to standard (such as capacity retention rate <95% after 50 cycles), it will feed the signal back to the formulation unit to automatically adjust the lithium salt concentration (±0.05mol / L) or the additive ratio (±0.1%) until the reuse requirements are met.

[0065] Example 3: Detailed working process of a closed-loop recovery method for lithium-ion battery electrolyte using multi-stage membrane separation coupled with catalytic enhancement and pulsed electrochemical regeneration. S1, Pre-processing stage (approximately 30 minutes): Waste electrolyte is passed into a precision filter at a flow rate of 80L / h to remove solid impurities with a particle size >5μm (such as electrode powder and membrane fragments). After filtration, the liquid enters a pH adjustment tank, lithium carbonate powder is added (addition amount 0.5-0.8 g / L), and the mixture is stirred for 10 minutes. The pH value is then measured to be 4.5-5.5. After pH adjustment, the liquid is fed into the dehydration membrane module and dehydrated at an operating temperature of 60℃ to obtain a pretreated liquid with a water content of <0.1%. S2, Deep Impurity Removal Stage (approximately 50 minutes): The pretreatment solution was introduced into the modified mesoporous SiO2@chitosan composite adsorption fixed bed at a flow rate of 2.7 L / min and retained for 30 min to remove Co. 2+ Ni 2+ ; The effluent was passed into a hydroxyapatite microsphere packed column at a flow rate of 4 L / min and held for 20 min to remove F⁻ and polymer residues. The resulting highly purified solution (Co) was then analyzed. 2+ The range is 0.03-0.05 ppm, Ni 2+ The range is 0.02-0.04 ppm, F - (range 0.6-0.8ppm) S3, Series-Parallel Membrane Separation Stage (Continuous Operation, Detection Every 2 Hours): The deep-purified liquid is passed into a parallel pretreatment membrane module (microfiltration operating pressure 0.2MPa, ultrafiltration operating pressure 0.3MPa) to remove suspended impurities and degradation polymers with molecular weight >1000Da; The permeate is passed into a two-stage series nanofiltration membrane group (operating pressure 0.5MPa), the lithium salt-additive mixture is retained (and sent to the regeneration unit), and the permeated organic solvent is passed into a parallel pervaporation membrane group (operating temperature 60℃). After purification, the solvent purity is ≥99.9% and it is stored in the solvent storage tank. When the pressure difference between the inlet and outlet of the membrane module is greater than 0.3 MPa, the intelligent control module automatically starts the online dynamic cleaning subsystem and performs cleaning according to the process of "rinsing with deionized water for 15 minutes for microfiltration / ultrafiltration and rinsing with dilute sulfuric acid for 10 minutes for nanofiltration". S4, Catalytically Enhanced Pulsed Electrochemical Regeneration Stage (approximately 45 minutes): The nanofiltration retentate (LiPF6 concentration detected at 0.9-1.1 mol / L) is fed into the regeneration chamber, and the electrode spacing is adjusted to 8-12 mm using a screw. Turn on gradient aeration (0.6-0.7 L / min at the bottom and 0.3-0.4 L / min in the middle) and catalytic stirrer (200 r / min), start the pulse power supply (2.5-3V, 600-700Hz, 50% duty cycle), and react for 45 min; After the reaction is completed, samples are taken to test the purity of LiPF6 in the regenerated solution, which is ≥99.9%, and then sent to the lithium salt storage tank. S5, Intelligent Adaptation and Feedback Phase (approximately 60 minutes): Input the target battery type (e.g., NCM811), and the intelligent control module calls the algorithm to control the solvent storage tank, lithium salt storage tank, and VC storage tank to deliver materials to the mixing tank in the ratio of "EC:DMC:EMC=3:5:2, LiPF6 1.2mol / L, VC 1%", and stir for 10 minutes (400r / min). Take 10mL of the mixture to assemble CR2032 button batteries and test them with the micro battery testing subsystem: the initial charge-discharge efficiency is 92-94% and the capacity retention rate after 50 cycles is 95-97%. If the standard is met, the batteries will be sent to the battery production line for reuse. If the standard is not met, the composition will be adjusted according to the feedback results (such as increasing the VC ratio to 1.1-1.2%) and then the batteries will be tested again.

[0066] The beneficial effects of a closed-loop recovery method for lithium-ion battery electrolyte based on multi-stage membrane separation coupled with catalytic enhancement and pulsed electrochemical regeneration: 1. Fully automated and easy to operate: The intelligent control module realizes closed-loop control of the entire process of "pretreatment-deep purification-membrane separation-regeneration-adjustment-reuse". Manual intervention is only required to replace the adsorption material and membrane module periodically, which is suitable for large-scale industrial applications.

[0067] Example 4, System Setup 1. Core equipment selection and parameters: Pretreatment unit: precision filter (MF-PVDF-5, pore size 5μm, throughput 80L / h), pH adjustment tank (500L, 316L stainless steel, stirrer speed 300r / min), dehydration membrane assembly (PV-01, silicone rubber composite membrane, dehydration rate ≥99.9%). Deep pretreatment module: modified mesoporous SiO2@chitosan adsorbent material (particle size 50-80μm, adsorption capacity 15mg / g, purchased from a new materials technology company), hydroxyapatite microspheres (particle size 20-30μm, porosity 65%, purchased from a biomaterials company), fixed bed and packed column volume are both 200L; Membrane separation module: microfiltration membrane (MF-0.2-PVDF, pore size 0.2μm, single unit capacity 40L / h), ultrafiltration membrane (UF-1000-PES, 1000Da cutoff, single unit capacity 40L / h), nanofiltration membrane (NF-200-PA, 200Da cutoff, single unit capacity 40L / h), pervaporation membrane (PV-EC / DMC, silicone rubber composite membrane, purification efficiency 99.9%), online dynamic cleaning subsystem (high pressure pump P-04, pressure 0.4MPa, cleaning fluid switching valve SV-03); Electrochemical regeneration device: Ruthenium-iridium-titanium coated electrode (coating thickness 5μm, area 0.5m²), nickel foam electrode (porosity 90%, area 0.5m²), screw adjustment support (electrode spacing 5-20mm), gradient aeration system (annular aeration disc + dotted aeration head), titanium-based catalytic stirrer (supported nano Ir catalyst, particle size 5-10nm, loading 0.8mg / cm²), pulse power supply (PE-10, 0-10V, 50-1000Hz); Mixing-feedback module: online concentration detector (CD-01, ±0.01mol / L), micro battery testing subsystem (BT-01, 0.1C charge-discharge, 50-cycle test), PLC controller (Siemens S7-1200, with touch screen operation interface); 2. Installation points: Piping and valves: All connecting pipes are made of polytetrafluoroethylene (50mm inner diameter, 5mm wall thickness), and the valves are corrosion-resistant solenoid valves (model SV-03, temperature resistance 100℃). The joints are sealed with fluororubber sealing rings. Membrane module installation: Membrane module verticality deviation ≤1°, inlet and outlet pipe length ≥1m (avoid sudden changes in flow velocity), flow distribution valves of parallel membrane modules need to be calibrated (flow deviation of each membrane module <5%). Electrochemical regeneration device: The cation exchange membrane must be in close contact with the electrode support (gap < 0.5 mm), the electrode spacing adjustment screw should be coated with fluorinated grease (model KF-96), and the aeration system must undergo a flow uniformity test (flow deviation at each aeration point < 10%). Intelligent control wiring: The wiring between the sensor and the PLC controller uses shielded wire (anti-interference). All electrical equipment must be grounded (grounding resistance < 4Ω) and the signal must be calibrated (pressure and flow detection error < 2%).

[0068] 3. Operating Procedures; Taking the treatment of electrolyte from retired NCM811 batteries as an example electrolyte initial parameters Retired NCM811 lithium-ion battery electrolyte: EC:DMC:EMC=3:5:2, initial LiPF6 concentration 1.2mol / L, VC content 1%, impurity content: Co 2+ Content 0.5ppm, Ni 2+ The content is 0.3ppm, the HF content is 5ppm, the moisture content is 0.8%, and the processing capacity is 80L / h.

[0069] Detailed operating procedures Step 1, System Startup and Parameter Settings: Activate the intelligent control module, input the target battery type "NCM811", and the system will automatically load the following parameters: pH adjustment target 5.0, adsorption fixed bed residence time 30 min, HAP packed column residence time 20 min, membrane separation pressure (microfiltration 0.2 MPa, ultrafiltration 0.3 MPa, nanofiltration 0.5 MPa), pervaporation temperature 60℃, regeneration parameters (electrode spacing 10 mm, voltage 3 V, frequency 600 Hz, aeration flow rate 0.7 L / min at the bottom / 0.4 L / min in the middle, reaction time 45 min), and mixing ratio "EC:DMC:EMC=3:5:2, LiPF6 content 1.2 mol / L, VC content 1%"; Step 2, Pretreatment and Deep Purification: Waste electrolyte is fed into a precision filter at a flow rate of 80 L / h via a feed pump. After filtration, it enters a pH adjustment tank, where lithium carbonate powder (0.6 g / L) is added and stirred for 10 min. The pH value measured by the pH meter is 5.0. The adjusted liquid is fed into the dehydration membrane module, and after dehydration, the water content is reduced to 0.08%, resulting in a pretreated liquid. The pretreatment solution was pumped into a modified mesoporous SiO2@chitosan adsorption fixed bed (flow rate 2.7 L / min), held for 30 min, and then fed into a HAP microsphere packed column (flow rate 4 L / min), held for 20 min, and then sampled for analysis: Co 2+ Content 0.04ppm, Ni 2 + Content 0.03ppm, F - The concentration is 0.7 ppm, indicating it is a deeply purified solution; Step 3, Membrane separation and cleaning: The deep-purified solution is fed into a parallel pretreatment membrane module. The inlet and outlet pressures of the microfiltration membrane are 0.2MPa / 0.15MPa, and the inlet and outlet pressures of the ultrafiltration membrane are 0.3MPa / 0.25MPa. The permeate enters a two-stage nanofiltration membrane module (inlet and outlet pressures 0.5MPa / 0.45MPa). The retentate (LiPF6 concentration 1.0mol / L) is sent to a regeneration unit. The permeated organic solvent enters a pervaporation membrane module (temperature 60℃). After purification, the solvent purity is 99.92%, and it is stored in a solvent storage tank. After running for 2 hours, the pressure difference between the inlet and outlet of the nanofiltration membrane rose to 0.35 MPa, and the system automatically started cleaning: the nanofiltration membrane feed valve was closed, and 0.05 mol / L dilute sulfuric acid (flow rate 40 L / h) was introduced to flush for 10 minutes. After flushing, the pressure difference dropped to 0.25 MPa, and normal operation was restored. Step 4, Electrochemical Regeneration: Nanofiltration retentate (1.0 mol / L LiPF6) was fed into the regeneration chamber. The screw electrode distance was adjusted to 10 mm. Gradient aeration (0.7 L / min at the bottom and 0.4 L / min in the middle) and catalytic stirrer (200 r / min) were turned on. The pulse power supply (3V, 600 Hz, 50% duty cycle) was started and the reaction was carried out for 45 min. After the reaction was completed, a sample was taken and the purity of LiPF6 was determined to be 99.93% using an ion chromatograph, and then sent to a lithium salt storage tank. Step 5, Configuration and Performance Testing: Solvent storage tanks (EC 270L, DMC 450L, EMC 180L), lithium salt storage tanks (1.2mol / L LiPF6 100L), and VC storage tanks (10L) are fed into the mixing tank in proportion and stirred for 10 minutes (400r / min). 10 mL of the mixture was used to assemble a CR2032 button cell (positive electrode NCM811, negative electrode graphite, separator Celgard 2400). The micro battery testing subsystem was used to test the following: the initial charge-discharge efficiency was 93.5%, and the capacity retention rate after 50 cycles was 96.2%, which met the standards. Step Six, Reuse and System Maintenance: The qualified recycled electrolyte is pumped into the NCM811 battery production line for reuse. After the system ran continuously for 8 hours, the feed pump was turned off, and all pipelines were rinsed with deionized water for 30 minutes. The adsorption capacity of the fixed adsorption bed was tested and found to be 12 mg / g (still meeting the requirements). The electrode coating was checked and found to be free of peeling, and the catalyst in the catalytic stirrer was found to be free of significant loss.

[0070] Maintenance points and troubleshooting Routine maintenance (cycle and operation): Membrane module maintenance: Backwash the microfiltration / ultrafiltration membrane with deionized water for 15 minutes every 8 hours; clean the nanofiltration membrane with 0.05mol / L dilute sulfuric acid for 10 minutes every 7 days; check the purity of the pervaporation membrane every 3 months (replace if <99.5%). Deep pretreatment module: Sample and test the adsorption capacity of the adsorption fixed bed every 30 days (replace the adsorption material if <5mg / g), replace the HAP microspheres every 60 days (if F - Removal rate < 98%) Electrochemical regeneration device: Observe the electrode coating with a microscope weekly (if the peeling area is >5%, sandblast and recoat, coating thickness 5μm), and ultrasonically clean the catalytic stirrer with deionized water for 5 minutes every 15 days (to remove the LiF precipitate attached to the surface). Intelligent control module: Monthly calibration of pressure sensor, flow sensor and concentration detector; quarterly update of "battery type-component matching database" (adding new battery system parameters, such as NCM622, LFP high voltage system); Common troubleshooting (phenomenon-cause-solution): Fault 1: Membrane flux drops sharply (<70% of design value); Cause: Severe accumulation of impurities on the membrane surface; Solution: Extend the online cleaning time to 20 minutes. If ineffective, soak the membrane module offline in 0.1 mol / L citric acid solution for 2 hours. After cleaning, test the flux recovery rate to ≥90%. Fault 2: LiPF6 regeneration purity < 99.8%; Cause: Decreased catalyst activity or uneven aeration; Measures: If catalyst shedding > 10%, replace the catalytic stirrer; if aeration is uneven, adjust the aeration flow rate (increase to 0.8 L / min at the bottom and 0.5 L / min in the middle), and extend the reaction time to 50 min. Fault 3: The micro battery cycle performance is not up to standard (capacity retention rate <95% after 50 cycles); Cause: Improper additive ratio or lithium salt concentration deviation; Solution: Feedback to the mixing unit, increase the VC ratio to 1.2% or adjust the LiPF6 concentration to 1.25mol / L, and re-mix and test; Fault 4: Pitch adjustment is stuck; Cause: Insufficient lubrication or impurities in the screw; Solution: Turn off the power, disassemble the screw, clean it with anhydrous ethanol, apply fluorinated grease, reinstall it, and test the smoothness of adjustment.

[0071] The effects that this application can achieve are: 1. To achieve the removal of heavy metal ions (Co) from the electrolyte. 2+ Ni 2+ Simultaneous and deep removal of free HF and polymeric residues ensures that Co in the purified solution is removed. 2+ Ni 2+ Content <0.05ppm, F - Content <0.8ppm; 2. Increase the membrane separation system's throughput to ≥80L / h, reduce the membrane flux decay rate to below 15% / 1000h, and extend the membrane module's service life to over 3500h; 3. The LiPF6 regeneration time is shortened to ≤45 min, the regeneration purity is increased to ≥99.9%, and the energy consumption is further reduced by 15% compared with traditional pulse electrolysis; 4. To achieve customized formulation of electrolytes for different battery systems, and to ensure that after reuse of the regenerated electrolyte, the capacity retention rate of the battery after 1000 cycles is ≥92% (NCM battery) and ≥94% (LFP battery).

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A closed-loop recovery system for lithium-ion battery electrolyte using multi-stage membrane separation coupled with catalytic enhancement and pulsed electrochemical regeneration, characterized in that, The system includes a pretreatment unit, an impurity targeted removal module, a dynamic cleaning integrated membrane separation module, a pulsed electrochemical regeneration device, a circulation feedback module, and an intelligent control module. These components are sequentially connected via connecting pipes. The intelligent control module controls the sensors, pumps, and valves in the pretreatment unit, impurity targeted removal module, dynamic cleaning integrated membrane separation module, and pulsed electrochemical regeneration device through electrical connections. The pretreatment unit includes a precision filter, a pH adjustment tank, and a dehydration membrane assembly; the impurity targeted removal module includes an adsorption fixed bed and a hydroxyapatite microsphere packed column. The dynamic cleaning integrated membrane separation module includes a parallel pretreatment membrane group, a dual-stage series nanofiltration membrane group, and a parallel pervaporation membrane group. These three groups are connected sequentially via pipelines. The parallel pretreatment membrane group includes a microfiltration membrane and an ultrafiltration membrane. The microfiltration membrane and ultrafiltration membrane are connected, with two sets of microfiltration membranes and two sets of ultrafiltration membranes arranged in parallel. The dual-stage series nanofiltration membrane group includes two nanofiltration membranes connected in series. The parallel pervaporation membrane group includes two sets of silicone rubber composite membranes connected in parallel. The pulsed electrochemical regeneration device includes an anode chamber, a regeneration chamber, and a cathode chamber, with adjacent chambers separated by a perfluorosulfonic acid resin cation exchange membrane; The cyclic feedback module includes a solvent storage tank, a lithium salt storage tank, an additive mixing tank, an online concentration detector, and a micro battery testing subsystem.

2. The lithium-ion battery electrolyte closed-loop recovery system with multi-stage membrane separation coupled with catalytic enhancement and pulsed electrochemical regeneration according to claim 1, characterized in that, The precision filter is made of PVDF with a pore size of 5μm, the pH adjustment tank has a volume of 500L, and the dehydration membrane assembly is a silicone rubber composite membrane.

3. The lithium-ion battery electrolyte closed-loop recovery system with multi-stage membrane separation coupled with catalytic enhancement and pulsed electrochemical regeneration according to claim 1, characterized in that, The adsorption bed is made of modified mesoporous SiO2@chitosan in series. The adsorption bed has a particle size of 50-80 μm and an adsorption capacity ≥15 mg / g. The hydroxyapatite microspheres in the packed column have a particle size of 20-30 μm and a porosity of 60-70%. The specific surface area of ​​the modified mesoporous SiO2@chitosan is 800-1000 m² / g, and the specific surface area of ​​the composite adsorption material is 800-1000 m² / g. The modified mesoporous SiO2@chitosan has a specific surface area of ​​800-1000 m² / g. 2+ and Ni 2+ The adsorption rate is ≥99.5%; hydroxyapatite microspheres have an adsorption rate of ≥99.5% for F. - The removal rate is ≥98%, and the hydroxyapatite microspheres retain polymeric residues with a molecular weight >5000Da.

4. The lithium-ion battery electrolyte closed-loop recovery system with multi-stage membrane separation coupled with catalytic enhancement and pulsed electrochemical regeneration according to claim 1, characterized in that, The microfiltration membrane in the pretreatment membrane assembly has a pore size of 0.2 μm and is made of PVDF. The ultrafiltration membrane in the pretreatment membrane assembly is a polyethersulfone ultrafiltration membrane with a molecular weight cutoff of 1000 Da.

5. The lithium-ion battery electrolyte closed-loop recovery system with multi-stage membrane separation coupled with catalytic enhancement and pulsed electrochemical regeneration according to claim 4, characterized in that, The nanofiltration membrane in the dual-stage tandem nanofiltration membrane group is an aromatic polyamide nanofiltration membrane.

6. The lithium-ion battery electrolyte closed-loop recovery system according to claim 5, characterized in that, The dynamic cleaning integrated membrane separation module is also equipped with a dynamic cleaning subsystem, which includes a cleaning solution tank and a high-pressure pulse pump. The cleaning solution tank stores deionized water and dilute sulfuric acid. When the membrane pressure difference in the dynamic cleaning integrated membrane separation module is >0.3MPa, the microfiltration membrane and ultrafiltration membrane are cleaned with deionized water for 15 minutes, and the nanofiltration membrane is cleaned with dilute sulfuric acid for 10 minutes.

7. The lithium-ion battery electrolyte closed-loop recovery system according to claim 1, characterized in that, The pulsed electrochemical regeneration device adopts a three-chamber split structure, consisting of an anode chamber, a regeneration chamber, and a cathode chamber from left to right. Adjacent chambers are separated by a perfluorosulfonic acid resin cation exchange membrane, which allows lithium ions to pass selectively and prevents solvent molecules and anions from mixing.

8. A closed-loop recovery method for lithium-ion battery electrolyte using multi-stage membrane separation coupled with catalytic enhancement and pulsed electrochemical regeneration, characterized in that, The method specifically includes the following steps: S1, Pretreatment: Waste electrolyte is passed into a precision filter at a flow rate of 80L / h. The filtrate enters a pH adjustment tank, and lithium carbonate powder is added to the pH adjustment tank to adjust the pH value to 4.5-5.

5. Then, the water content is reduced to below 0.1% by the dehydration membrane module to obtain the pretreated solution. S2, deep impurity removal: the pretreatment solution is introduced into the adsorption fixed bed at a flow rate of 2.7 L / min and stays in the adsorption fixed bed for 30 minutes, and then introduced into the microsphere packed column at a flow rate of 4 L / min and stays in the microsphere packed column for 20 minutes to obtain the deep purified solution; S3, series-parallel membrane separation: the deep purified liquid is passed into the parallel pretreatment membrane group to obtain the permeate, the permeate is passed into the two-stage series nanofiltration membrane group to obtain the retentate, the retentate is sent to the pulse electrochemical regeneration device, and the permeated organic solvent is purified by the parallel pervaporation membrane group and then stored; when the membrane pressure difference is >0.3MPa, the online dynamic cleaning integrated membrane separation module is started. S4, catalytically enhanced pulsed electrochemical regeneration: the retentate is first sent into the regeneration chamber of the pulsed electrochemical regeneration device, the electrode distance is adjusted, gradient aeration and catalytic stirrer are turned on, a pulse voltage of 2.5-3V, 600-700Hz, and 50% duty cycle is applied, and the reaction time is 45min to obtain LiPF6 regenerated solution. S5 features intelligent adaptation, adjustment, and feedback. Input the target battery type, and the cyclic feedback module delivers solvent, regenerated lithium salt, and additives to the mixing tank according to the matching formula and stirs them evenly. Take the mixture to assemble micro batteries for testing. If it meets the standards, it can be reused; if it does not meet the standards, the components are adjusted and the test is repeated until the reuse requirements are met.

9. The closed-loop recovery method for lithium-ion battery electrolyte using multi-stage membrane separation coupled with catalytic enhancement and pulsed electrochemical regeneration according to claim 8, characterized in that, When the LiPF6 concentration in the retentate is >1.2mol / L, the electrode spacing is adjusted to 15-20mm; when the LiPF6 concentration is <0.8mol / L, the electrode spacing is adjusted to 5-10mm.

10. The closed-loop recovery method for lithium-ion battery electrolyte using multi-stage membrane separation coupled with catalytic enhancement and pulsed electrochemical regeneration according to claim 8, characterized in that, Co in the deep purification liquid in S2 2+ and Ni 2+ The content of F is <0.05ppm. - <0.8ppm.

11. The closed-loop recovery method for lithium-ion battery electrolyte using multi-stage membrane separation coupled with catalytic enhancement and pulsed electrochemical regeneration according to claim 8, characterized in that, The purity of the LiPF6 regenerated solution in S4 is greater than 99.9%.

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