Polyacid modified chitosan composite polymer electrolyte material, preparation method and application thereof
Patent Information
- Application Number
- CN202610997402.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-06
- Publication Date
- 2026-09-22
AI Technical Summary
现有无机固态电解质（硫化物、氧化物、卤化物），具有高离子电导率（10-4~10-3Scm-1）和宽的电化学窗口，但是脆性大、界面接触差、制备条件苛刻、成本高；聚合物固态电解质（PEO、PVDF、PAN基）具有柔韧性好、界面相容性优、易加工成膜等优势，但在室温下离子电导率低（<10-5S cm-1），且机械强度差、热稳定性差
壳聚糖（CS）因具有丰富极性官能团（-NH2、-OH），为锂离子传输提供了潜在配位位点和迁移路径。然而，壳聚糖分子间因氢键密集，严重阻碍实际离子传导效果。本发明采用的POM具有成本低、分子结构明确、原子组成可调、表面化学作用丰富等特性。通过静电作用、氢键作用与壳聚糖分子均匀组装结合，可实现多酸在壳聚糖材料内均匀分散和跨尺度界面相互作用。同时，POM具有强吸电子特性，通过组装可有效降低壳聚糖极性官能团（如-OH、-NH2）周围电子云密度，促进官能团与锂盐阴离子(如FSI-)结合，该调节作用可破除锂盐中阴阳离子对(Li+...FSI-)间强束缚，促进锂盐解离以提高自由Li+浓度。同时，均匀亚纳米尺度分散的POM簇可有效破坏壳聚糖分子间的氢键网络，为离子传输提供更便捷的链段运动空间和传输路径。
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Figure CN122800730A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium metal solid-state battery technology, specifically relating to a polyacid-modified chitosan composite polymer electrolyte material, its preparation method, and its application. Background Technology
[0002] Current liquid lithium-ion batteries suffer from safety hazards such as electrolyte leakage, flammability, and explosion, and their energy density is approaching its theoretical limit. Solid-state electrolytes can effectively solve safety issues, are compatible with lithium metal anodes, and significantly improve energy density, making them a core technology for next-generation high-energy-density batteries. Existing inorganic solid-state electrolytes (sulfides, oxides, halides) possess high ionic conductivity (10⁻⁶ Ω·cm). -4 ~10 -3 Scm -1 Polymer solid electrolytes (PEO, PVDF, PAN-based) offer advantages such as good flexibility, excellent interfacial compatibility, and ease of film formation, but suffer from low ionic conductivity (<10 Ω·cm) at room temperature. -5 S cm -1 Furthermore, it exhibits poor mechanical strength and thermal stability. Adding fillers to the polymer matrix through blending can improve these problems, but this generally results in issues such as particle agglomeration, interruption of ion conduction pathways, increased interfacial impedance, and instability. Summary of the Invention
[0003] The purpose of this invention is to provide a polyacid-modified chitosan composite polymer electrolyte material, its preparation method, and its application, to address the problems existing in current solid-state battery technology. This invention utilizes the strong electrostatic and hydrogen bonding interactions between polyacid (POM) clusters and the hydroxyl / amino groups of chitosan. This not only breaks the dense hydrogen bond network between chitosan molecules, reducing steric hindrance for lithium ion migration, but also enhances the anchoring effect of chitosan polar functional groups on lithium salt anions by reducing their electron cloud density, thus promoting lithium salt dissociation. Based on these synergistic effects, this invention significantly improves the ionic conductivity, ion transport number, mechanical strength, interfacial compatibility, and cycle stability of the composite polymer electrolyte used in lithium metal solid-state batteries.
[0004] This invention is achieved through the following technical solution: A method for preparing polyacid-modified chitosan composite polymer electrolyte materials includes the following steps: Chitosan was dissolved in an acidic aqueous solution of a predetermined concentration by stirring to obtain mixture A; The polyacid was dissolved in water by stirring to obtain mixture B; Add mixture B to mixture A, stir and react at a preset temperature for a preset time, centrifuge and wash, and vacuum dry the obtained sample to obtain polyacid-modified chitosan material; Polyvinylidene fluoride or polyethylene oxide is mixed with lithium salt and polyacid-modified chitosan material in a preset ratio, then solvent is added and stirred thoroughly, followed by vacuum drying to obtain polyacid-modified chitosan composite polymer electrolyte material.
[0005] Furthermore, the acidic aqueous solution is an aqueous solution of acetic acid.
[0006] Furthermore, the concentration of the acidic aqueous solution is 0.17 mol / L, and 0.5 g of chitosan is dissolved in every 50 mL of the acidic aqueous solution.
[0007] Furthermore, the polyacid is H3PMo. 12 O 40 or H3PW 12 O 40 .
[0008] Furthermore, dissolve 0.1~0.5 g of polyacid in every 30 mL of water.
[0009] Furthermore, the mass ratio of polyacid in mixture B to the mass of chitosan in mixture A is (1~5):5.
[0010] Furthermore, the preset temperature is 20-40 ℃, and the preset time is 2-12 h.
[0011] Furthermore, when polyvinylidene fluoride is used, the mass ratio of polyvinylidene fluoride to lithium salt is 3:2, the solvent is DMF solvent, and 0.4g of polyvinylidene fluoride is dissolved in every 10 mL of DMF solvent; When polyethylene oxide is used, the molar ratio of polyethylene oxide to lithium salt is 20:1, the solvent is acetonitrile, and 0.67g of polyethylene oxide is dissolved in 10 mL of acetonitrile solvent; The amount of the polyacid-modified chitosan material added is 2.5-7.5% of the total mass of polyvinylidene fluoride or polyethylene oxide and lithium salt; The lithium salt is LiTFSI, LiFSI, or LiClO4; The vacuum drying temperature is 60-80 ℃, and the time is 12-20 h.
[0012] The polyacid-modified chitosan composite polymer electrolyte material was prepared using the method described above.
[0013] Application of polyacid-modified chitosan composite polymer electrolyte materials in lithium metal batteries or lithium-ion batteries.
[0014] Compared with the prior art, the present invention has the following beneficial technical effects: Chitosan (CS) possesses abundant polar functional groups (-NH2, -OH), providing potential coordination sites and migration pathways for lithium-ion transport. However, the dense hydrogen bonds between chitosan molecules severely hinder actual ion conduction. The POM used in this invention possesses characteristics such as low cost, well-defined molecular structure, tunable atomic composition, and rich surface chemical interactions. Through electrostatic interactions, hydrogen bonding, and uniform assembly with chitosan molecules, polyacids can be uniformly dispersed within the chitosan material and interact across scales. Simultaneously, POM exhibits strong electron-withdrawing properties; through assembly, it can effectively reduce the electron cloud density around the polar functional groups (such as -OH, -NH2) of chitosan, promoting interaction between these functional groups and lithium salt anions (such as FSI). - This regulatory effect can break the pairing of cation and anion (Li) in lithium salts. +... FSI - Strong binding between lithium salts promotes lithium salt dissociation and increases the free lithium content. + Concentration. Meanwhile, the uniformly dispersed sub-nanometer POM clusters can effectively disrupt the hydrogen bond network between chitosan molecules, providing a more convenient space for chain segment movement and transport pathways for ion transport.
[0015] Furthermore, Li can be adsorbed on the surface of POM clusters. + And as a site for rapid ion transition, Li + Low-barrier hopping is achieved between POM surface sites and between POM and chitosan polar groups, enabling synergistic construction of spatially efficient Li + Ion transport channels. The aforementioned cross-scale intermolecular (CS-POM) synergistic effect is the fundamental reason for the significant improvement in ionic conductivity and transport number of the composite electrolyte membrane.
[0016] Furthermore, when POM-modified chitosan materials are dispersed in polyvinylidene fluoride or vinyl oxide matrix to form a composite polymer electrolyte, their strong polarity and hydrogen bond breaking properties can further regulate the crystallization behavior of the matrix polymer (such as inducing the β-phase transformation of PVDF or reducing the crystallinity of PEO), thereby constructing a continuous and rapid lithium-ion transport pathway at the internal interface of the electrolyte membrane, ultimately significantly improving the ionic conductivity and Li-ion conductivity of the polymer solid electrolyte. + Migration number provides a new feasible path for realizing the application of high energy density and high safety solid-state batteries (lithium metal batteries or lithium-ion batteries). Attached Figure Description
[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. The following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.
[0018] Figure 1 A high-magnification transmission electron microscope image of the polyacid-modified chitosan material prepared in Example 1 of the present invention; Figure 2 Charge-discharge curves of the polyacid-modified chitosan composite polymer electrolyte prepared in Example 1 of the present invention; Figure 3 The cycling stability diagrams are shown for the composite polymer electrolytes prepared in Example 1, Comparative Example 1, and Comparative Example 2 of this invention. Figure 4 The ionic conductivity diagrams are shown for the composite polymer electrolytes prepared in Examples 1, 2, and 6 of this invention and Comparative Example 1. Figure 5 Li, the polyacid-modified chitosan composite polymer electrolyte prepared in Example 1 of this invention + Ion transport number plot. Detailed Implementation
[0019] The present invention will now be described in detail: This invention provides a method for preparing a polyacid-modified chitosan composite polymer electrolyte material, comprising the following steps: Chitosan was dissolved by stirring in an acidic aqueous solution of a predetermined concentration to obtain mixture A, wherein the acidic aqueous solution was an acetic acid aqueous solution with a concentration of 0.17 mol / L. -1 And 0.5g of chitosan is dissolved in every 50 mL of acidic aqueous solution; The polyacid was dissolved in water by stirring to obtain mixture B, wherein the polyacid was phosphomolybdic acid (H3PMo). 12 O 40 ) or phosphotungstic acid (H3PW) 12 O 40 Dissolve 0.2~0.4 g of polyacid in every 30 mL of water; Add mixture B to mixture A, reflux and stir at 20-40 ℃ for 2-12 h and centrifuge and wash, place the obtained sample in a vacuum drying oven at 80 ℃ for 12 h to obtain polyacid-modified chitosan material, wherein the mass ratio of polyacid in mixture B to chitosan in mixture A is (1~5):5; Polyvinylidene fluoride (PVDF) or polyethylene oxide (PEO) is mixed with lithium salt (LiTFSI, LiFSI or LiClO4) and polyacid-modified chitosan material in a solvent, and then vacuum dried to obtain polyacid-modified chitosan composite polymer electrolyte material. When using polyvinylidene fluoride (PVDF), PVDF and lithium salt are mixed in DMF at a mass ratio of 3:2. Acid-modified chitosan material is added to the system at a ratio of 2.5% to 7.5% of the total mass of PVDF and lithium salt. The mixture is ultrasonically or mechanically stirred until homogeneous. The solution is then cast into a Teflon mold and dried in a vacuum drying oven at 60–80 °C for 12–20 h to remove the solvent, yielding a acid-modified chitosan composite polymer solid electrolyte membrane.
[0020] When using polyethylene oxide, polyethylene oxide and lithium salt are mixed in acetonitrile at a molar ratio of 20:1. The polyacid-modified chitosan material is added to the system at a ratio of 1% to 10% of the total mass of polyethylene oxide and lithium salt. The mixture is stirred evenly by ultrasonication or mechanical stirring. The mixture is then cast into a Teflon mold and dried in a vacuum drying oven at 60 °C for 14 h to remove the solvent, thus obtaining a polyacid-modified chitosan composite polymer solid electrolyte membrane.
[0021] The above-mentioned polyacid-modified chitosan composite polymer solid electrolyte was punched into discs with a diameter of 19 mm. To evaluate the performance of the polyacid-modified chitosan composite polymer solid electrolyte, lithium iron phosphate was used as the positive electrode, with an active material loading of 1.5~2 mg·cm³. -2 The lithium metal battery uses lithium foil as the negative electrode, while the lithium-ion battery uses silicon-carbon as the negative electrode. The CR2025 button cell battery was assembled in an argon-filled glove box and subjected to constant current charge-discharge tests with a voltage range of 2.8-4.0 V.
[0022] This invention is the first to propose utilizing polyacids to disrupt the intermolecular hydrogen bond network of chitosan. The continuous, rapid transition sites provided by the polyacid clusters and the synergistic effect between these sites and the polar groups of chitosan create a highly efficient, low-resistance lithium-ion transport channel. Compared to traditional polyethylene oxide or unmodified chitosan-based solid electrolytes, this invention, through the synergistic effect of polyacids, chitosan, and PVDF, significantly improves ionic conductivity and lithium-ion transference number, enhances electrode / electrolyte interface compatibility, and thus improves the cycle stability of lithium metal batteries. This invention provides a novel composite polymer electrolyte material with innovative structure, simple processing, and controllable cost for high-energy-density, high-safety lithium metal solid-state batteries.
[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise specified, the methods and experimental equipment used in the following embodiments are conventional methods and instruments.
[0024] Example 1 This embodiment provides a method for preparing a chitosan composite polymer electrolyte material modified with polyacids. The detailed steps of this preparation method are as follows: a. Dissolve 0.5 g of chitosan in 50 mL of a 0.17 mol / L solution by stirring. -1 In an aqueous solution of acetic acid.
[0025] b. Add 0.3 g H3PMo 12 O 40 Dissolve in 30 mL of water.
[0026] c. Slowly add the solution from step b to the solution from step a, stir the reaction at 25 °C for 6 h and centrifuge and wash, then place the sample in a vacuum drying oven and dry at 80 °C for 12 h to obtain the polyacid-modified chitosan material.
[0027] d. Mix polyvinylidene fluoride (PVDF) and LiFSI in DMF at a mass ratio of 3:2, dissolving 0.4 g of PVDF in every 10 mL of DMF solvent. Add the polyacid-modified chitosan material to the system at a ratio of 5% of the total mass of PVDF and lithium salt. Stir evenly by ultrasonication or mechanical stirring. Cast the mixed solution into a Teflon mold and dry it in a vacuum drying oven at 80 °C for 14 h to remove the solvent, thus obtaining the polyacid-modified chitosan composite polymer solid electrolyte material.
[0028] Depend on Figure 1 As can be seen, no obvious aggregated particles were observed in the HRTEM images, indicating that polyoxometalates (POMs) are uniformly dispersed in the chitosan matrix at the sub-nanometer level. Figure 2 It can be seen that the lithium metal battery prepared based on the polyacid-modified chitosan composite polymer solid electrolyte material obtained in Example 1 has a discharge capacity as high as 163 mAh g at a current density of 0.1 C at room temperature. -1 .Depend on Figure 3 It can be seen that the lithium metal battery prepared in Example 1 retains 94% of its capacity after 1000 cycles at 2C rate, demonstrating excellent cycle stability. Figure 4 It can be seen that the composite polymer electrolyte prepared in Example 1 has an ionic conductivity as high as 8.8 × 10⁻⁶ at room temperature. -4 S cm -1 .Depend on Figure 5 It can be seen that, based on the polyacid-modified chitosan composite polymer solid electrolyte material obtained in Example 1, the Li at room temperature... + The ion transference number is as high as 0.63.
[0029] Example 2 This embodiment provides a method for preparing a chitosan composite polymer electrolyte material modified with polyacids. The detailed steps of this preparation method are as follows: a. Dissolve 0.5 g of chitosan in 50 mL of a 0.17 mol / L solution. -1 Aqueous solution of acetic acid.
[0030] b. Add 0.3 g H3PMo 12 O 40 Dissolve in 30 mL of water.
[0031] c. Slowly add the solution from step b to the solution from step a, stir the reaction at 20 °C for 6 h and centrifuge and wash, then place the sample in a vacuum drying oven and dry at 80 °C for 12 h to obtain the polyacid-modified chitosan material.
[0032] d. Polyvinylidene fluoride (PVDF) and LiFSI were mixed in DMF at a mass ratio of 3:2, with 0.4 g of PVDF dissolved in every 10 mL of DMF solvent. The polyacid-modified chitosan material was added to the system at a ratio of 2.5% of the total mass of PVDF and lithium salt. The mixture was then fully dispersed by ultrasonic or mechanical stirring. The mixed solution was cast into a Teflon mold and dried in a vacuum drying oven at 80 °C for 14 h to remove the solvent, thus obtaining the polyacid-modified chitosan composite polymer solid electrolyte material.
[0033] Depend on Figure 5 It can be seen that the polyacid-modified chitosan composite polymer solid electrolyte material prepared in Example 2 has an ionic conductivity of 2.4 × 10⁻⁶ at room temperature. -4 S cm -1 The lithium metal battery prepared based on the polyacid-modified chitosan composite polymer solid electrolyte material obtained in Example 2 has an initial specific capacity of 147 mAh g at a 0.5 C rate. -1 After 300 cycles, the capacity retention rate is still 94%.
[0034] Example 3 This embodiment provides a method for preparing a chitosan composite polymer electrolyte material modified with polyacids. The detailed steps of this preparation method are as follows: a. Dissolve 0.5 g of chitosan in 50 mL of a 0.17 mol / L solution by stirring. -1 Aqueous solution of acetic acid.
[0035] b. Add 0.3 g H3PMo 12 O 40 Dissolve in 30 mL of water.
[0036] c. Slowly add the solution from step b to the solution from step a, stir the reaction at 25 °C for 6 h and centrifuge and wash, then place the sample in a vacuum drying oven and dry at 80 °C for 12 h to obtain the polyacid-modified chitosan material.
[0037] d. Mix polyethylene oxide and LiClO4 in acetonitrile at a molar ratio of 20:1, dissolving 0.67g of polyethylene oxide in every 10 mL of acetonitrile solvent. Add the polyacid-modified chitosan material to the system at a ratio of 5% of the total mass of polyethylene oxide and lithium salt. Stir evenly by ultrasonication or mechanical stirring. Cast the mixed solution into a Teflon mold and dry it in a vacuum drying oven at 80 ℃ for 14 h to remove the solvent, thus obtaining the polyacid-modified chitosan composite polymer solid electrolyte material.
[0038] The lithium metal battery prepared based on the polyacid-modified chitosan composite polymer solid electrolyte material obtained in Example 3 exhibits an initial specific capacity of 150 mAh g⁻¹ at a 0.5 C rate. -1 After 250 cycles, the capacity retention rate was 89%.
[0039] Example 4 This embodiment provides a method for preparing a chitosan composite polymer electrolyte material modified with polyacids. The detailed steps of this preparation method are as follows: a. Dissolve 0.5 g of chitosan in 50 mL of a 0.17 mol / L solution by stirring. -1 Aqueous solution of acetic acid.
[0040] b. Add 0.3 g H3PW 12 O 40 Dissolve in 30 mL of water.
[0041] c. Slowly add the solution from step b to the solution from step a, stir and react at 20 °C for 12 h, centrifuge and wash, then place the sample in a vacuum drying oven and dry at 80 °C for 12 h to obtain the polyacid-modified chitosan material.
[0042] d. Mix polyvinylidene fluoride (PVDF) and LiClO4 in DMF at a mass ratio of 3:2, and dissolve 0.4 g of PVDF in every 10 mL of DMF solvent. Add the polyacid-modified chitosan material to the system at a ratio of 5% of the total mass of PVDF and lithium salt. Stir evenly by ultrasonication or mechanical stirring. Cast the mixed solution into a Teflon mold and dry it in a vacuum drying oven at 80 °C for 14 h to remove the solvent, thereby obtaining the polyacid-modified chitosan composite polymer solid electrolyte material.
[0043] Example 5 This embodiment provides a method for preparing a chitosan composite polymer electrolyte material modified with polyacids. The detailed steps of this preparation method are as follows: a. Dissolve 0.5 g of chitosan in 50 mL of a 0.17 mol / L solution by stirring. -1 Aqueous solution of acetic acid.
[0044] b. Add 0.3 g H3PMo 12 O 40 Dissolve in 30 mL of water.
[0045] c. Slowly add the solution from step b to the solution from step a, stir the reaction at 25 °C for 6 h and centrifuge and wash, then place the sample in a vacuum drying oven and dry at 80 °C for 12 h to obtain the polyacid-modified chitosan material.
[0046] d. Mix polyvinylidene fluoride (PVDF) and LiFSI in DMF at a mass ratio of 3:2, and dissolve 0.4 g of PVDF in every 10 mL of DMF solvent. Add the polyacid-modified chitosan material to the system at a ratio of 5% of the total mass of PVDF and lithium salt. Disperse the mixture thoroughly by ultrasonic or mechanical stirring. Cast the mixed solution into a Teflon mold and dry it in a vacuum drying oven at 80 °C for 12 h to remove the solvent, thus obtaining the polyacid-modified chitosan composite polymer solid electrolyte material.
[0047] The lithium metal battery prepared based on the polyacid-modified chitosan composite polymer solid electrolyte material obtained in Example 5 has an initial specific capacity of 119 mAh g at 2 C rate. -1 After 600 cycles, the capacity retention rate was 80%.
[0048] Example 6 This embodiment provides a method for preparing a chitosan composite polymer electrolyte material modified with polyacids. The detailed steps of this preparation method are as follows: a. Dissolve 0.5 g of chitosan in 50 mL of a 0.17 mol / L solution by stirring. -1 Aqueous solution of acetic acid.
[0049] b. Add 0.3 g H3PMo 12 O 40 Dissolve in 30 mL of water.
[0050] c. Slowly add the solution from step b to the solution from step a, stir the reaction at 25 °C for 6 h and centrifuge and wash, then place the sample in a vacuum drying oven and dry at 80 °C for 12 h to obtain the polyacid-modified chitosan material.
[0051] d. Mix polyvinylidene fluoride (PVDF) and LiFSI in DMF at a mass ratio of 3:2, dissolving 0.4 g of PVDF in every 10 mL of DMF solvent. Add the polyacid-modified chitosan material to the system at a ratio of 7.5% of the total mass of PVDF and lithium salt. Stir evenly by ultrasonication or mechanical stirring. Cast the mixed solution into a Teflon mold and dry it in a vacuum drying oven at 80 °C for 14 h to remove the solvent, thus obtaining the polyacid-modified chitosan composite polymer solid electrolyte material.
[0052] Depend on Figure 4 It can be seen that the polyacid-modified chitosan composite polymer electrolyte material prepared in Example 6 has an ionic conductivity as high as 7.4 × 10⁻⁶ at room temperature. -4 S cm -1 .
[0053] Example 7 This embodiment provides a method for preparing a chitosan composite polymer electrolyte material modified with polyacids. The detailed steps of this preparation method are as follows: a. Dissolve 0.5 g of chitosan in 50 mL of 0.17 mol / L solution by stirring. -1 An aqueous solution of acetic acid.
[0054] b. Add 0.4 g H3PMo 12 O 40 Dissolve in 30 mL of water.
[0055] c. Slowly add the solution from step b to the solution from step a, stir and react at 40 °C for 2 h, centrifuge and wash, then place the sample in a vacuum drying oven and dry at 80 °C for 12 h to obtain the polyacid-modified chitosan material.
[0056] d. Mix polyvinylidene fluoride (PVDF) and LiTFSI in DMF at a mass ratio of 3:2, and dissolve 0.4 g of PVDF in every 10 mL of DMF solvent. Add the polyacid-modified chitosan material to the system at a ratio of 2.5% of the total mass of PVDF and lithium salt. Stir evenly by ultrasonication or mechanical stirring. Cast the mixed solution into a Teflon mold and dry it in a vacuum drying oven at 70 °C for 20 h to remove the solvent, thereby obtaining the polyacid-modified chitosan composite polymer solid electrolyte material.
[0057] The lithium metal battery prepared based on the polyacid-modified chitosan composite polymer solid electrolyte material obtained in Example 7 has an initial specific capacity of 128 mAh g at 1 C rate. -1 After 400 cycles, the capacity retention rate is still 88%.
[0058] Example 8 This embodiment provides a method for preparing a chitosan composite polymer electrolyte material modified with polyacids. The detailed steps of this preparation method are as follows: a. Dissolve 0.5 g of chitosan in 50 mL of 0.17 mol / L solution by stirring. -1 An aqueous solution of acetic acid.
[0059] b. Add 0.2 g H3PMo 12 O 40 Dissolve in 30 mL of water.
[0060] c. Slowly add the solution from step b to the solution from step a, stir and react at 20 °C for 2 h, centrifuge and wash, then place the sample in a vacuum drying oven and dry at 80 °C for 12 h to obtain the polyacid-modified chitosan material.
[0061] d. Mix polyvinylidene fluoride (PVDF) and LiTFSI in DMF at a mass ratio of 3:2, dissolving 0.4 g of PVDF in every 10 mL of DMF solvent. Add the polyacid-modified chitosan material to the system at a ratio of 2.5% of the total mass of PVDF and lithium salt. Stir evenly by ultrasonication or mechanical stirring. Cast the mixed solution into a Teflon mold and dry it in a vacuum drying oven at 60 °C for 20 h to remove the solvent, thus obtaining the polyacid-modified chitosan composite polymer solid electrolyte material.
[0062] The lithium metal battery prepared based on the polyacid-modified chitosan composite polymer solid electrolyte material obtained in Example 8 has an initial specific capacity of 123 mAh g at 1 C rate. -1 After 340 cycles, the capacity retention rate was 67%.
[0063] Example 9 This embodiment provides a method for preparing a chitosan composite polymer electrolyte material modified with polyacids. The detailed steps of this preparation method are as follows: a. Dissolve 0.5 g of chitosan in 50 mL of 0.17 mol / L solution by stirring. -1 An aqueous solution of acetic acid.
[0064] b. Add 0.3 g H3PMo 12 O 40 Dissolve in 30 mL of water.
[0065] c. Slowly add the solution from step b to the solution from step a, stir the reaction at 20 °C for 6 h and centrifuge and wash, then place the sample in a vacuum drying oven and dry at 80 °C for 12 h to obtain the polyacid-modified chitosan material.
[0066] d. Mix polyvinylidene fluoride (PVDF) and LiTFSI in DMF at a mass ratio of 3:2, and dissolve 0.4 g of PVDF in every 10 mL of DMF solvent. Add the polyacid-modified chitosan material to the system at a ratio of 5% of the total mass of PVDF and lithium salt. Stir evenly by ultrasonication or mechanical stirring. Cast the mixed solution into a Teflon mold and dry it in a vacuum drying oven at 80 °C for 14 h to remove the solvent, thus obtaining the polyacid-modified chitosan composite polymer solid electrolyte material.
[0067] The lithium-ion battery prepared based on the polyacid-modified chitosan composite polymer solid electrolyte material obtained in Example 9 exhibits an initial specific capacity of 114 mAh g⁻¹ at a 0.2 C rate. -1 .
[0068] Comparative Example 1 This comparative example provides a method for preparing a PVDF polymer electrolyte, the detailed steps of which are as follows: Polyvinylidene fluoride (PVDF) and LiFSI were mixed in DMF at a mass ratio of 3:2, with 0.4 g of PVDF dissolved in every 10 mL of DMF solvent. The mixture was mechanically stirred until dissolved, then cast into a Teflon mold and dried in a vacuum oven at 80 °C for 14 h to remove the solvent, yielding a chitosan composite polymer solid electrolyte membrane. The solid electrolyte was then punched into discs with a diameter of 19 mm. To evaluate the electrolyte's performance, lithium foil was used as the negative electrode, and lithium iron phosphate as the positive electrode, with an active material loading of approximately 1.5–2 mg·cm³. -2 CR2025 button batteries were assembled in an argon-filled glove box and subjected to constant current charge-discharge tests with a voltage range of 2.8-4.0 V.
[0069] Depend on Figure 3 It can be seen that the lithium metal battery prepared based on the PVDF polymer electrolyte obtained in Comparative Example 1 retained 64% of its capacity after 318 cycles at 2 C rate. The ionic conductivity of the PVDF polymer electrolyte prepared in Comparative Example 1 at room temperature is 1.3 × 10⁻⁶. -4 S cm -1 The PVDF polymer electrolyte prepared in Comparative Example 1 had an ion transport number of 0.33 at room temperature.
[0070] Comparative Example 2 This comparative example provides a method for preparing a chitosan composite polymer electrolyte material, the detailed steps of which are as follows: Polyvinylidene fluoride (PVDF) and LiFSI were mixed in DMF at a mass ratio of 3:2, with 0.4 g of PVDF dissolved in every 10 mL of DMF solvent. Chitosan was added to the system at a ratio of 5% of the total mass of PVDF and lithium salt. The mixture was stirred evenly by ultrasonication or mechanical stirring. The mixture was then cast into a Teflon mold and dried in a vacuum drying oven at 80 °C for 14 h to remove the solvent, yielding a chitosan composite polymer solid electrolyte membrane.
[0071] Depend on Figure 3 It can be seen that the lithium metal battery prepared based on the chitosan composite polymer electrolyte material obtained in Comparative Example 2 retains 62% of its capacity after 900 cycles at 2 C rate. The chitosan composite polymer electrolyte prepared in Comparative Example 2 exhibits a high Li-metal capacity retention of 62% at room temperature. + The ion transport number is 0.51.
[0072] By comparing Example 1 with Comparative Examples 1 and 2, it can be seen that chitosan is rich in polar functional groups such as hydroxyl (-OH) and amino (-NH2), which interact with lithium salt anions (such as FSI). - The binding of ions and anions in lithium salts can alleviate the effects of Li+ cation-anion pairing. +... FSI - The constraints between them release more freedom. + Meanwhile, the -OH and -NH2 groups of chitosan can anchor residual DMF solvent through hydrogen bonds, reducing its direct contact with lithium metal and improving interfacial stability. Through polyacid modification of chitosan, the abundant oxygen atoms on the POM surface can serve as Lewis base sites to adsorb a large amount of Li. + Furthermore, POM further reduces the electron cloud density of -NH2, weakening its effect on Li. + Strong coordination promotes lithium salt dissociation and increases the free Li + Concentration, improving ionic conductivity. POM optimizes Li in the electrolyte membrane after assembly with chitosan. + The distribution and transport pathways guide the formation of a stable solid electrolyte interface film, effectively suppressing lithium dendrite growth. Therefore, the ion ionization conductivity in Example 1, Li + The migration number and cycle stability were significantly higher than those of Comparative Example 1 and Comparative Example 2.
[0073] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.
Claims
1. A method for preparing polyacid-modified chitosan composite polymer electrolyte materials, characterized in that, Includes the following steps: Chitosan was dissolved in an acidic aqueous solution of a predetermined concentration by stirring to obtain mixture A; The polyacid was dissolved in water by stirring to obtain mixture B; Add mixture B to mixture A, stir and react at a preset temperature for a preset time, centrifuge and wash, and vacuum dry the obtained sample to obtain polyacid-modified chitosan material; Polyvinylidene fluoride or polyethylene oxide is mixed with lithium salt and polyacid-modified chitosan material in a preset ratio, then solvent is added and stirred thoroughly, followed by vacuum drying to obtain polyacid-modified chitosan composite polymer electrolyte material.
2. The preparation method of the polyacid-modified chitosan composite polymer electrolyte material according to claim 1, characterized in that, The acidic aqueous solution is an acetic acid aqueous solution.
3. The method for preparing the polyacid-modified chitosan composite polymer electrolyte material according to claim 1, characterized in that, The concentration of the acidic aqueous solution is 0.17 mol / L, and 0.5 g of chitosan is dissolved in every 50 mL of the acidic aqueous solution.
4. The method for preparing the polyacid-modified chitosan composite polymer electrolyte material according to claim 1, characterized in that, The polyacid is H3PMo. 12 O 40 or H3PW 12 O 40 .
5. The method for preparing the polyacid-modified chitosan composite polymer electrolyte material according to claim 1, characterized in that, Dissolve 0.1~0.5 g of polyacid in every 30 mL of water.
6. The method for preparing the polyacid-modified chitosan composite polymer electrolyte material according to claim 1, characterized in that, The mass ratio of polyacid in mixture B to the mass of chitosan in mixture A is (1~5):
5.
7. The method for preparing the polyacid-modified chitosan composite polymer electrolyte material according to claim 1, characterized in that, The preset temperature is 20-40 ℃, and the preset time is 2-12 h.
8. The method for preparing the polyacid-modified chitosan composite polymer electrolyte material according to claim 1, characterized in that, When polyvinylidene fluoride (PVDF) is used, the mass ratio of PVDF to lithium salt is 3:2, the solvent is DMF, and 0.4 g of PVDF is dissolved in every 10 mL of DMF. When polyethylene oxide is used, the molar ratio of polyethylene oxide to lithium salt is 20:1, the solvent is acetonitrile, and 0.67g of polyethylene oxide is dissolved in 10 mL of acetonitrile solvent; The amount of the polyacid-modified chitosan material added is 2.5-7.5% of the total mass of polyvinylidene fluoride or polyethylene oxide and lithium salt; The lithium salt is LiTFSI, LiFSI, or LiClO4; The vacuum drying temperature is 60-80 ℃, and the time is 12-20 h.
9. A polyacid-modified chitosan composite polymer electrolyte material, characterized in that, It is prepared by the preparation method according to any one of claims 1-8.
10. The application of the polyacid-modified chitosan composite polymer electrolyte material according to claim 9 in lithium metal batteries or lithium-ion batteries.