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CN-122010148-A - Modified composite electrode based on copper hexacyanoferrate, and preparation method and application thereof

CN122010148ACN 122010148 ACN122010148 ACN 122010148ACN-122010148-A

Abstract

The invention relates to the technical field of capacitor deionization, in particular to a modified composite electrode based on copper hexacyanoferrate, a preparation method and application thereof, wherein the modified composite electrode sequentially comprises a CuHCF substrate, an N-heterocycle functional group grafted on the surface of the CuHCF substrate, a selective framework film growing on the surface of the CuHCF substrate and a self-repairing polymer layer coated on the surface of the selective framework film from inside to outside, the selective framework film is made of a functionalized framework material, and the aperture of the selective framework film is 3.0A to 5.0A. According to the invention, through optimizing structure and functional modification, the selectivity to NH 4 + is enhanced, and meanwhile, the cycling stability and interface stability of the electrode are improved, so that the efficient and long-acting capacitive deionization removal of NH 4 + in the lithium-rich solution is realized, and the upgrading of the battery-grade lithium carbonate purification technology is promoted.

Inventors

  • MA XIUMEI
  • ZHU ZHENGYOU
  • LI FAQIANG
  • SHANGGUAN XUEHUI

Assignees

  • 临沂大学

Dates

Publication Date
20260512
Application Date
20260211

Claims (10)

  1. 1. The modified composite electrode based on the copper hexacyanoferrate is characterized by sequentially comprising a CuHCF substrate, an N-heterocyclic functional group grafted on the surface of the CuHCF substrate, a selective framework film growing on the surface of the CuHCF substrate and a self-repairing polymer layer coated on the surface of the selective framework film from inside to outside, wherein the selective framework film is made of a functionalized framework material, and the aperture of the selective framework film is 3.0 to 5.0A.
  2. 2. The modified composite electrode based on copper hexacyanoferrate according to claim 1, wherein the nitrogen heterocyclic functional group is obtained by grafting through covalent bonding reaction of CuHCF substrate surface hydroxyl groups and a compound containing pyridine groups or imidazole groups.
  3. 3. The modified composite electrode based on copper hexacyanoferrate of claim 2, wherein the compound containing pyridine group comprises one of pyridine-3-carboxylic acid, 4-pyridylaldehyde, 2-aminopyridine, and pyridyldicarboxylic anhydride, and the compound containing imidazole group comprises one of imidazolecarboxaldehyde, imidazole-4-carbaldehyde, and 2-methylimidazole.
  4. 4. The modified composite electrode based on copper hexacyanoferrate of claim 1, wherein the functional groups in the functionalized framework material comprise one or more of amino groups, crown ether units, carboxyl groups, sulfonic acid groups, pyridyl groups, imidazole groups.
  5. 5. The modified composite electrode of claim 4, wherein the functionalized frame material comprises one of NH 2 -MIL-101、NH 2 -MIL-53、NH 2 -UiO-66、ZIF-8、MIL-88B-NH 2 、TpPa-NH 2 、TpBD-NH 2 、COF-LZU1、TAPB-TPA-COF、Py-1P-COF.
  6. 6. The modified composite electrode based on copper hexacyanoferrate of claim 1, wherein the self-healing polymer in the self-healing polymer layer is a dynamic cross-linked polymer comprising one of a polyethylene glycol diamine-glyoxal acylhydrazone cross-linked polymer, a polyethylene glycol diacrylate-dithiothreitol disulfide cross-linked polymer, a polycaprolactone diol-isophorone diisocyanate-cystamine disulfide cross-linked polymer, and a polycaprolactone diol-ethylenediamine-glyoxal acylhydrazone cross-linked polymer.
  7. 7. The method for preparing the modified composite electrode based on copper hexacyanoferrate according to any one of claims 1-6, comprising the following steps: S1, preparing CuHCF, namely synchronously injecting a CuCl 2 ・2H 2 O solution and a K 3 [Fe(CN) 6 solution into deionized water by adopting a coprecipitation method, standing, centrifuging, washing and drying to obtain CuHCF powder; S2, nitrogen heterocyclic functional group grafting, namely carrying out reflux reaction on CuHCF powder of S1 after activation and a compound containing pyridine groups or imidazole groups in a DMF solvent, and washing and drying to obtain N-CuHCF grafted with the nitrogen heterocyclic functional group; S3, selectively growing a frame film in situ, namely preparing N-CuHCF of the S2 into an electrode matrix, performing plasma treatment, then immersing the electrode matrix into a functional frame material precursor solution for liquid phase epitaxial growth, and performing activation treatment to obtain an electrode with the selectively grown frame film in situ, wherein the N-CuHCF@selectively grown frame film electrode; S4, sealing the self-repairing polymer, namely immersing the N-CuHCF@selective frame film electrode of the S3 into a self-repairing polymer solution for immersing and heat treating to obtain the modified composite electrode.
  8. 8. The preparation method of the modified composite electrode based on copper hexacyanoferrate as claimed in claim 7, wherein CuHCF powder in S2 is activated to disperse CuHCF powder in absolute ethyl alcohol, ultrasonic treatment is carried out for 20-40 min, then vacuum drying is carried out, the temperature of reflux reaction is 80-100 ℃, and the reaction time is 8-12 h.
  9. 9. The preparation method of the modified composite electrode based on copper hexacyanoferrate, which is characterized in that the plasma treatment time in S3 is 5-10 min, the liquid phase epitaxial growth temperature is 60-80 ℃, the heat preservation time is 6-10 h, the activation treatment temperature is 110-130 ℃, and the heat preservation time is 3-5 h.
  10. 10. The application of the modified composite electrode based on copper hexacyanoferrate as claimed in any one of claims 1-6, wherein the application is in the efficient capacitive deionization removal of ammonium ions in a lithium-rich solution, the modified composite electrode is adopted as a cathode, an activated carbon electrode is adopted as an anode, an anion exchange membrane group HCDI battery is matched, capacitive deionization treatment is carried out on the lithium-rich solution under the working voltage of 0.8-1.2V, and the molar concentration ratio of the lithium ions to the ammonium ions in the lithium-rich solution is 3:1-10:1.

Description

Modified composite electrode based on copper hexacyanoferrate, and preparation method and application thereof Technical Field The invention relates to the technical field of capacitive deionization, in particular to a modified composite electrode based on copper hexacyanoferrate, and a preparation method and application thereof. Background Lithium Ion Batteries (LIBs) are used as core energy storage devices in the field of new energy sources, and the performance and the safety of the lithium ion batteries are highly dependent on the purity of a precursor of a positive electrode material, in particular to battery-grade lithium carbonate. In the process of lithium carbonate production and lithium resource recovery, ammonium ions (NH 4+) are harmful impurities which are difficult to avoid, and even trace residues can cause serious damage to lithium ion batteries. NH 4+ has thermal instability, is easy to decompose and generate ammonia under the conditions of charge and discharge cycle or high temperature of the battery, so that the internal pressure of the battery is increased, the shell is expanded, the degradation of an electrode-electrolyte interface is accelerated, the service life of the battery is obviously shortened, and potential safety hazards are caused. Therefore, the deep removal of NH 4+ in a lithium rich solution (such as lithium carbonate production mother liquor, lithium resource recovery liquor and the like) is a key link for guaranteeing the purity of battery-grade lithium carbonate. The traditional NH 4+ removal technology mainly comprises a chemical precipitation method, an air stripping method and the like, but the methods have obvious defects that the chemical precipitation method is easy to cause excessive loss of lithium ions and reduce the utilization rate of lithium resources, the air stripping method needs harsh conditions such as high temperature or acid-base adjustment, has high energy consumption and is easy to produce secondary pollution, and the environment-friendly and efficient purification requirements are difficult to meet. The Hybrid Capacitive Deionization (HCDI) technology is used as an emerging low-energy separation technology, realizes ion-specific separation through the synergistic effect of a Faraday electrode and a capacitive component, has the advantages of mild operation, no chemical addition, low energy consumption and the like, and provides a new direction for removing NH 4+ in a lithium-rich solution. Copper hexacyanoferrate (CuHCF) is typically represented as a Prussian blue analog, has a rigid face-centered cubic lattice structure with a lattice pore size of 3.2A, and based on the ion hydration radius difference (NH 4+ hydration radius 3.31A < Li + hydration radius 3.82A), selective intercalation of NH 4+ can be achieved, becoming an ideal cathode material for NH 4+ removal in HCDI systems. However, the conventional CuHCF-based electrode still faces the following technical bottlenecks when being applied in a lithium rich solution (1) the selectivity is insufficient, only a single selection mechanism of lattice size difference is relied on, under a high lithium concentration background, the competitive adsorption of Li + leads to limited NH 4+ selectivity coefficient (the maximum of about 4.1 in the prior art), deep removal of NH 4+ is difficult to realize, (2) the cyclic stability is poor, the repeated intercalation/deintercalation of Li + can cause CuHCF lattice distortion in the long-term adsorption-desorption cyclic process, microcracks are easy to occur on the surface of the electrode, meanwhile Cu 2+ is easy to dissolve in electrolyte, the electrode performance is fast attenuated, the selectivity coefficient is obviously reduced to about 3.0 after 50 cycles, and (3) the interface stability is insufficient, the CuHCF matrix is easy to undergo side reaction when being directly contacted with the electrolyte, so that the long-term operation reliability of an HCDI system is influenced. Disclosure of Invention The invention aims to provide a modified composite electrode based on copper hexacyanoferrate, a preparation method and application thereof, which strengthen the selectivity to NH 4+ by optimizing structure and functional modification, and improve the cycling stability and interface stability of the electrode at the same time, thereby realizing the efficient and long-acting capacity deionization removal of NH 4+ in lithium-rich solution and promoting the upgrading of battery-grade lithium carbonate purification technology. In order to achieve the aim, the invention provides a modified composite electrode based on copper hexacyanoferrate, which sequentially comprises a CuHCF substrate, an N-heterocycle functional group grafted on the surface of the CuHCF substrate, a selective framework film growing on the surface of the CuHCF substrate and a self-repairing polymer layer coated on the surface of the selective framework film from inside to outside, where