Preparation method of composite solid electrolyte membrane and composite solid electrolyte membrane
A composite solid electrolyte membrane was prepared by combining a mixture of polyethylene oxide, lithium carboxymethyl cellulose, and lithium salt with plasticizer impregnation, vacuum drying, and hot pressing processes. This solved the problem of balancing environmental protection and high ionic conductivity in existing technologies, and enabled the production of efficient and environmentally friendly electrolyte membranes.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- DONGFENG MOTOR GRP
- Filing Date
- 2024-08-15
- Publication Date
- 2026-07-21
Smart Images
Figure CN119133588B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of solid electrolyte membrane preparation technology, and in particular to a method for preparing a composite solid electrolyte membrane and the composite solid electrolyte membrane. Background Technology
[0002] Traditional alkyl carbonate electrolyte lithium-ion batteries are prone to electrolyte evaporation and leakage during operation, especially under conditions such as compression, impact, or short circuits. This can easily lead to thermal runaway and safety accidents. However, lithium-ion batteries using solid-state electrolytes do not have these problems, resulting in a significant safety improvement compared to alkyl carbonate electrolyte batteries. However, traditional lithium-ion batteries use solid inorganic electrolytes, which have poor mechanical properties. Therefore, most current lithium-ion batteries use solid polymer electrolytes.
[0003] However, solid polymer electrolytes are usually prepared by solution casting. Although solution casting is highly efficient, it still has many problems: (1) the solution casting process generates a large amount of toxic solvent vapors, polluting the environment; (2) the film-forming efficiency of the solution casting method is low; (3) the solution casting process requires long-term vacuum drying, which may cause the polymer to recrystallize during the vacuum drying process, affecting the ionic conductivity of the solid polymer electrolyte; (4) the solution casting process may also result in polymer deposition, leading to non-uniformity of the electrolyte film and affecting the ionic conductivity of the solid polymer electrolyte. Therefore, existing methods for preparing solid polymer electrolytes cannot simultaneously achieve both high ionic conductivity and environmental friendliness. Summary of the Invention
[0004] This application provides a method for preparing a composite solid electrolyte membrane and the composite solid electrolyte membrane itself, in order to solve the following technical problem: how to balance the environmental friendliness of the solid polymer electrolyte preparation process with high ionic conductivity.
[0005] In a first aspect, this application provides a method for preparing a composite solid electrolyte membrane, the method comprising:
[0006] Polyethylene oxide, lithium carboxymethyl cellulose, and lithium salt are mixed to obtain a mixture;
[0007] The mixture is impregnated with a plasticizer to induce a plasticizing reaction, thereby obtaining an impregnated mixture;
[0008] The impregnation mixture is subjected to vacuum drying to remove excess plasticizer, thereby obtaining a solid electrolyte membrane raw material;
[0009] The solid electrolyte membrane raw material is hot-pressed to obtain a composite solid electrolyte membrane;
[0010] The weight m1 of the plasticizer and the weight m2 of the mixture satisfy the following relationship: m1:m2=(0.9~1.1):1.
[0011] Optionally, the immersion temperature is 75℃~85℃, and the immersion time is ≥12h.
[0012] Optionally, the vacuum drying temperature is 75℃~85℃, and the vacuum drying time is 30min~120min.
[0013] Optionally, the content of residual plasticizer in the solid electrolyte membrane raw material and the mass ratio of the solid electrolyte membrane raw material satisfy the following: residual plasticizer: solid electrolyte membrane raw material ≤ 0.1.
[0014] Optionally, the hot pressing temperature is 50℃~80℃, and the hot pressing time is 0.5min~1.5min.
[0015] Optionally, the pressure of the hot pressing is 5MPa to 20MPa.
[0016] Optionally, the lithium salt includes at least one of the following:
[0017] Lithium bis(trifluoromethanesulfonyl)imide, lithium perchlorate, lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate, lithium tetrafluoroborate, and lithium dioxalate borate.
[0018] Optionally, the plasticizer includes at least one of the following:
[0019] Ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate.
[0020] Optionally, the weight m3 of the polyethylene oxide, the weight m4 of the lithium carboxymethyl cellulose, and the weight m5 of the lithium salt satisfy the relationship: m3:m4:m5=(4~7):(4~1):2.
[0021] Secondly, this application provides a composite solid electrolyte membrane, which is prepared by the preparation method described in the first aspect.
[0022] Optionally, the thickness of the composite solid electrolyte membrane is 20 μm to 200 μm.
[0023] The technical solutions provided in this application have the following advantages compared with the prior art:
[0024] This application provides a method for preparing a composite solid electrolyte membrane. The method includes: mixing polyethylene oxide, lithium carboxymethyl cellulose, and a lithium salt to obtain a mixture; impregnating the mixture with a plasticizer to induce a plasticizing reaction, obtaining an impregnated mixture; vacuum drying the impregnated mixture to remove excess plasticizer, obtaining a solid electrolyte membrane raw material; and hot-pressing the solid electrolyte membrane raw material to obtain a composite solid electrolyte membrane. The weight m1 of the plasticizer and the weight m2 of the mixture satisfy the relationship: m1:m2 = 0.9–1.1:1. This preparation method uses polyethylene oxide and lithium carboxymethyl cellulose as raw materials. Lithium carboxymethyl cellulose has a large number of hydroxyl groups and lithium ions. During the hot-pressing stage, lithium carboxymethyl cellulose with a large number of hydroxyl groups has good compatibility with polyethylene oxide, while lithium ions can open up the cellulose during the hot-pressing stage. The internal molecular channels enhance lithium-ion flux, thereby improving the ionic conductivity of the composite solid electrolyte membrane without the addition of organic solvents. Simultaneously, lithium carboxymethyl cellulose exhibits good tensile strength and tensile strain; after hot pressing, it can suppress the formation of lithium dendrites in the composite solid electrolyte membrane. Furthermore, the mass ratio of plasticizer to the mixture can be 0.9–1.1:1 to ensure sufficient plasticizer content. Sufficient plasticizer increases the uniformity of mixing polyethylene oxide, lithium carboxymethyl cellulose, and lithium salt, thereby improving the ionic conductivity of the composite solid electrolyte membrane. In addition, sufficient plasticizer improves the plasticity of the mixture, facilitating subsequent hot pressing to composite the solid electrolyte membrane, thus avoiding the use of large amounts of organic solvents. Therefore, this preparation method can improve both the ionic conductivity and environmental friendliness of the composite solid electrolyte membrane. Attached Figure Description
[0025] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.
[0026] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0027] Figure 1 This is a schematic flowchart illustrating a method for preparing a composite solid electrolyte membrane according to an embodiment of this application.
[0028] Figure 2 This is a schematic diagram of a composite solid electrolyte membrane provided in an embodiment of this application;
[0029] Figure 3 This is a schematic diagram comparing the AC impedance of the composite solid electrolyte membranes obtained in Example 1 and Comparative Example 1 of this application. Detailed Implementation
[0030] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0031] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values within that range; for example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range such as 1, 2, 3, 4, 5, and 6, regardless of the range; in addition, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.
[0032] In this document, terms such as “comprising” mean “including but not limited to”. Relational terms such as “first” and “second” are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. “And / or” describes the relationship between related objects, indicating that there can be three relationships, for example, A and / or B can mean: A exists alone, A and B exist simultaneously, or B exists alone; where A and B can be singular or plural. “At least one” means one or more, “more” means two or more; “at least one,” “at least one of the following,” or similar expressions refer to any combination of these items, including any combination of single or plural items; for example, “at least one of a, b, or c,” or “at least one of a, b, and c,” can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.
[0033] It should be noted that among the many polymers used in solid polymer electrolytes, polyethylene oxide (PEO) is one of the most promising polymers for solid polymer electrolytes due to its good lithium salt solubility and ion complexing ability. However, PEO has high crystallinity at room temperature, which leads to a relatively low ionic conductivity (approximately 10). -8 S / cm). Carboxymethyl cellulose can be added to polyethylene oxide to improve its performance. Since carboxymethyl cellulose contains a large number of hydroxyl groups, it has good compatibility with polyethylene oxide. In addition, the carboxyl groups of carboxymethyl cellulose can be easily replaced by metal ions. Therefore, the solid electrolyte formed by using polyethylene oxide and carboxymethyl cellulose has good eco-friendliness, low cost and additional ion transport properties.
[0034] Figure 1 An exemplary schematic diagram of a method for preparing a composite solid electrolyte membrane according to an embodiment of this application is shown;
[0035] like Figure 1 As shown in the figure, this application provides a method for preparing a composite solid electrolyte membrane, the preparation method comprising:
[0036] S1. Mix polyethylene oxide, lithium carboxymethyl cellulose, and lithium salt to obtain a mixture;
[0037] S2. Impregnate the mixture with a plasticizer to induce a plasticizing reaction in the mixture, thereby obtaining an impregnated mixture;
[0038] S3. The impregnation mixture is subjected to vacuum drying to remove excess plasticizer, thereby obtaining a solid electrolyte membrane raw material;
[0039] S4. The solid electrolyte membrane raw material is hot-pressed to obtain a composite solid electrolyte membrane;
[0040] The weight m1 of the plasticizer and the weight m2 of the mixture satisfy the following relationship: m1:m2=(0.9~1.1):1;
[0041] In these embodiments, the weight m1 of the plasticizer and the weight m2 of the mixture can satisfy the relationship: m1:m2=(0.9~1.1):1, so as to ensure that there is a sufficient amount of plasticizer in the mixture. On the one hand, the sufficient amount of plasticizer can increase the uniformity of mixing of polyethylene oxide, lithium carboxymethyl cellulose and lithium salt, thereby improving the ionic conductivity of the composite solid electrolyte membrane. On the other hand, the sufficient amount of plasticizer can improve the plasticity of the mixture, which makes it convenient to composite the solid electrolyte membrane by hot pressing only, thereby avoiding the use of a large amount of organic solvents.
[0042] The weight m1 of the plasticizer and the weight m2 of the mixture can satisfy the following relationship: m1:m2 = 0.9:1, 1.0:1 or 1.1:1.
[0043] It should be noted that lithium carboxymethyl cellulose is an effective electrode binder that can enhance intercrystalline adhesion and increase lithium-ion flux. The coulombic efficiency and charge / discharge capacity of lithium carboxymethyl cellulose are higher than those of sodium carboxymethyl cellulose. In addition, the inherent tensile strength and tensile strain of lithium carboxymethyl cellulose are beneficial for suppressing the formation of lithium dendrites in composite solid electrolyte membranes.
[0044] It should be noted that the preparation process of lithium carboxymethyl cellulose is as follows:
[0045] Under an inert gas atmosphere, sodium carboxymethyl cellulose was reacted with a mixture of ethanol and acetic acid (volume ratio of ethanol as molecule and acetic acid as denominator was 85:15) at 35°C for 3 hours to obtain a mixture; the mixture was then filtered, washed with a mixture of ethanol and water (volume ratio of ethanol as molecule and acetic acid as denominator was 85:15), and then dried in a vacuum oven at 80°C to obtain carboxymethyl cellulose acid;
[0046] Under an inert gas atmosphere, carboxymethyl cellulose acid was reacted with a mixture of lithium hydroxide monohydrate, ethanol, and water at 50°C for 3 hours. After the reaction was complete, the pH of the mixture was neutralized to 7 using acetic acid to eliminate residual hydroxides (OH-) in the sample. - The reaction product was obtained by filtration of a mixture of ethanol and water (ethanol as the molecule and acetic acid as the denominator in a volume ratio of 85:15) and then dried in a vacuum oven at 80°C to obtain pure lithium carboxymethyl cellulose.
[0047] In some optional embodiments, the immersion temperature is 75°C to 85°C, and the immersion time is ≥12 hours;
[0048] In these embodiments, the immersion temperature can be 75°C to 85°C, and the immersion time is generally ≥12h, which can promote sufficient mixing between the plasticizer and the mixture, thereby improving the plasticity of the mixture and the uniformity of mixing of polyethylene oxide, lithium carboxymethyl cellulose and lithium salt in the mixture. This makes it convenient to composite solid electrolyte membranes by hot pressing only, thus avoiding the use of a large amount of organic solvents.
[0049] The immersion temperature can be 75℃, 76℃, 77℃, 78℃, 79℃, 80℃, 81℃, 82℃, 83℃, 84℃ or 85℃.
[0050] In some optional embodiments, the vacuum drying temperature is 75°C to 85°C, and the vacuum drying time is 30 min to 120 min;
[0051] In this embodiment, the vacuum drying temperature can be 75°C to 85°C, and the vacuum drying time can be 230 min to 120 min. Excess plasticizer in the impregnation mixture can be completely removed by vacuum drying to avoid the plasticizer affecting the electrochemical and mechanical properties of the composite solid electrolyte membrane, thereby improving the ionic conductivity and mechanical properties of the composite solid electrolyte membrane.
[0052] The vacuum drying temperature can be 75℃, 76℃, 77℃, 78℃, 79℃, 80℃, 81℃, 82℃, 83℃, 84℃ or 85℃.
[0053] The vacuum drying time can be 30 min, 60 min, 90 min or 120 min.
[0054] In some optional embodiments, the content of plasticizer in the solid electrolyte membrane raw material and the mass ratio of the solid electrolyte membrane raw material are ≤0.1;
[0055] In this embodiment, the ratio of the plasticizer content to the mass of the solid electrolyte membrane raw material is generally ≤0.1, indicating that the plasticizer content in the solid electrolyte membrane raw material is within an appropriate range. This avoids excess plasticizer from affecting the electrochemical and mechanical properties of the composite solid electrolyte membrane, thereby improving the ionic conductivity and mechanical properties of the composite solid electrolyte membrane.
[0056] In some optional embodiments, the hot pressing temperature is 50°C to 80°C, and the hot pressing time is 0.5 min to 1.5 min;
[0057] In this embodiment, the hot pressing temperature can be 50°C to 80°C, and the hot pressing time can be 0.5 min to 1.5 min, which can promote the transformation of the solid electrolyte membrane raw material into a composite solid electrolyte membrane, so that the composite solid electrolyte membrane has sufficient thickness and sufficient mechanical properties, thereby improving the ionic conductivity and mechanical properties of the composite solid electrolyte membrane.
[0058] The hot pressing temperature can be 50℃, 55℃, 60℃, 65℃, 70℃, 75℃ or 80℃.
[0059] The hot pressing time can be 0.5 min, 1.0 min, or 1.5 min.
[0060] In some optional embodiments, the pressure of the hot pressing is 5 MPa to 20 MPa;
[0061] In this embodiment, the hot pressing pressure can be 5MPa to 20MPa, which can cause the solid electrolyte membrane raw material to be transformed into a composite solid electrolyte membrane, so that the composite solid electrolyte membrane has sufficient thickness and sufficient mechanical properties.
[0062] The pressure of the hot pressing can be 5MPa, 6MPa, 7MPa, 8MPa, 9MPa, 10MPa, 11MPa, 12MPa, 13MPa, 14MPa, 15MPa, 16MPa, 17MPa, 18MPa, 19MPa or 20MPa.
[0063] In some alternative embodiments, the lithium salt comprises at least one of the following:
[0064] Lithium bis(trifluoromethanesulfonyl)imide, lithium perchlorate, lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate, lithium tetrafluoroborate, and lithium dioxalate borate;
[0065] In this embodiment, the lithium salt may include at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium perchlorate, lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate, lithium tetrafluoroborate, and lithium dioxalate borate, which can reduce the risk of lithium dendrite formation in the composite solid electrolyte membrane and thereby improve the ionic conductivity of the composite solid electrolyte membrane.
[0066] In some alternative embodiments, the plasticizer includes at least one of the following:
[0067] Ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate;
[0068] In this embodiment, the plasticizer may include at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate. The plasticizer can increase the uniformity of mixing of polyethylene oxide, lithium carboxymethyl cellulose, and lithium salt, thereby improving the ionic conductivity of the composite solid electrolyte membrane. In addition, the plasticizer can also improve the plasticity of the mixture, making it easier to composite the solid electrolyte membrane by hot pressing, thus avoiding the use of a large amount of organic solvents.
[0069] In some optional embodiments, the weight m3 of the polyethylene oxide, the weight m4 of the lithium carboxymethyl cellulose, and the weight m5 of the lithium salt satisfy the relationship: m3:m4:m5=(4~7):(4~1):2;
[0070] In this embodiment, the weight m3 of polyethylene oxide, the weight m4 of lithium carboxymethyl cellulose, and the weight m5 of lithium salt can satisfy the relationship: m3:m4:m5=(4~7):(4~1):2, which can promote sufficient mixing between polyethylene oxide, lithium carboxymethyl cellulose, and lithium salt, so as to facilitate the subsequent transformation of these raw materials into composite solid electrolyte membrane by hot pressing.
[0071] The weights m3 of the polyethylene oxide, m4 of the lithium carboxymethyl cellulose, and m5 of the lithium salt can satisfy the following relationship: m3:m4:m5 = 4:4:2, 4:4:2, 4:3:2, 4:2:2, 4:1:2, 5:4:2, 5:4:2, 5:3:2, 5:2:2, 5:1:2, 6:4:2, 6:4:2, 6:3:2, 6:2:2, 6:1:2, 7:4:2, 7:4:2, 7:3:2, 7:2:2, or 7:1:2.
[0072] Figure 2 An exemplary schematic diagram of a composite solid electrolyte membrane provided in this application is shown.
[0073] Based on a general inventive concept, such as Figure 2 As shown in the embodiment of this application, a composite solid electrolyte membrane is provided, which is prepared by the preparation method described above.
[0074] The composite solid electrolyte membrane is prepared based on the above-described preparation method. The specific steps of the preparation method can be referred to the above embodiments. Since the composite solid electrolyte membrane adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated here.
[0075] In some optional embodiments, the thickness of the composite solid electrolyte membrane is 20 μm to 200 μm;
[0076] In these embodiments, the thickness of the composite solid electrolyte membrane can be 20 μm to 200 μm, indicating that the thickness of the composite solid electrolyte membrane is thin enough to improve the ionic conductivity of the composite solid electrolyte membrane while maintaining sufficient mechanical properties.
[0077] The thickness of the composite solid electrolyte membrane can be 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm, 190μm or 200μm.
[0078] The present application is further illustrated below with reference to specific embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to industry standards; if no corresponding industry standard exists, they are performed according to general international standards, conventional conditions, or conditions recommended by the manufacturer.
[0079] Example 1
[0080] like Figure 2 As shown, a method for preparing a composite solid electrolyte membrane includes:
[0081] S1. Mix 0.7g of polyethylene oxide, 0.1g of lithium carboxymethyl cellulose and 0.2g of lithium salt and place them in a glass bottle, then transfer them into a glove box to obtain a mixture of polyethylene oxide and lithium carboxymethyl cellulose.
[0082] S2. Weigh out 1.0g of plasticizer, then add the plasticizer to the mixture of polyethylene oxide, lithium carboxymethyl cellulose and lithium salt and stir to mix. Then impregnate the mixture to promote the plasticization reaction and obtain the impregnated mixture.
[0083] S3. The impregnated mixture is vacuum dried to remove excess plasticizer, and the residual amount of plasticizer is verified by thermogravimetric analysis to obtain solid electrolyte membrane raw material;
[0084] S4. Hot-press the solid electrolyte membrane raw material to obtain a composite solid electrolyte membrane, denoted as CMC-Li1-PEO-LiTFSI;
[0085] The weight of the plasticizer m1 and the weight of the mixture m2 satisfy the relationship: m1:m2=1:1.
[0086] The soaking temperature was 80℃, and the soaking time was 12 hours.
[0087] The vacuum drying temperature is 80℃, and the vacuum drying time is 60 minutes.
[0088] The content of plasticizer in the solid electrolyte membrane raw material and the mass ratio of the solid electrolyte membrane raw material are ≤0.1.
[0089] The hot pressing temperature is 60℃, and the hot pressing time is 1.0 min.
[0090] The pressure for hot pressing is 10 MPa.
[0091] The lithium salt is lithium bis(trifluoromethanesulfonylimide).
[0092] The plasticizer is propylene carbonate.
[0093] The weights of polyethylene oxide (m3), lithium carboxymethyl cellulose (m4), and lithium salt (m5) satisfy the following relationship: m3:m4:m5 = 7:1:2.
[0094] Example 2
[0095] Based on the content disclosed in Example 1, the following modifications are made:
[0096] The weight of polyethylene oxide is 0.6g, the weight of lithium carboxymethyl cellulose is 0.2g, the weight of lithium salt is 0.2g, and the weight of plasticizer is 1.0g.
[0097] The weights of polyethylene oxide (m3), lithium carboxymethyl cellulose (m4), and lithium salt (m5) satisfy the following relationship: m3:m4:m5 = 6:2:2.
[0098] The resulting composite solid electrolyte membrane is denoted as CMC-Li2-PEO-LiTFSI.
[0099] Example 3
[0100] Based on the content disclosed in Example 1, the following modifications are made:
[0101] The weight of polyethylene oxide is 0.5g, the weight of lithium carboxymethyl cellulose is 0.3g, the weight of lithium salt is 0.2g, and the weight of plasticizer is 1.0g.
[0102] The weights of polyethylene oxide (m3), lithium carboxymethyl cellulose (m4), and lithium salt (m5) satisfy the following relationship: m3:m4:m5 = 5:3:2.
[0103] The resulting composite solid electrolyte membrane is denoted as CMC-Li3-PEO-LiTFSI.
[0104] Example 4
[0105] Based on the content disclosed in Example 1, the following modifications are made:
[0106] The weight of polyethylene oxide is 0.4g, the weight of lithium carboxymethyl cellulose is 0.4g, the weight of lithium salt is 0.2g, and the weight of plasticizer is 1.0g.
[0107] The weights of polyethylene oxide (m3), lithium carboxymethyl cellulose (m4), and lithium salt (m5) satisfy the relationship: m3:m4:m5 = 4:4:2.
[0108] The resulting composite solid electrolyte membrane is denoted as CMC-Li4-PEO-LiTFSI.
[0109] Example 5
[0110] Based on the content disclosed in Example 1, the following modifications are made:
[0111] The immersion temperature is 75℃.
[0112] The vacuum drying temperature was 75℃, and the vacuum drying time was 120 minutes.
[0113] The hot pressing temperature is 80℃, and the hot pressing time is 0.5min.
[0114] The pressure for hot pressing is 5 MPa.
[0115] The resulting composite solid electrolyte membrane is denoted as CMC-Li5-PEO-LiTFSI.
[0116] Example 6
[0117] Based on the content disclosed in Example 1, the following modifications are made:
[0118] The immersion temperature is 85℃.
[0119] The vacuum drying temperature was 85℃, and the vacuum drying time was 60 minutes.
[0120] The hot pressing temperature is 50℃, and the hot pressing time is 1.5min.
[0121] The pressure for hot pressing is 20 MPa.
[0122] The resulting composite solid electrolyte membrane is denoted as CMC-Li6-PEO-LiTFSI.
[0123] Comparative Example 1
[0124] Based on the content disclosed in Example 1, the following modifications are made:
[0125] Without the addition of lithium carboxymethyl cellulose, the weight of polyethylene oxide is 0.8g, the weight of lithium salt is 0.2g, and the weight of plasticizer is 1.0g.
[0126] The resulting composite solid electrolyte membrane is denoted as PEO-LiTFSI.
[0127] Comparative Example 2
[0128] Based on the content disclosed in Example 1, the following modifications are made:
[0129] The weight of polyethylene oxide is 0.7g, the weight of lithium carboxymethyl cellulose is 0.5g, the weight of lithium salt is 0.2g, and the weight of plasticizer is 1.0g.
[0130] The resulting composite solid electrolyte membrane is denoted as Li1-PEO-LiTFSI.
[0131] Comparative Example 3
[0132] Based on the content disclosed in Example 1, the following modifications are made:
[0133] The immersion temperature is 70℃.
[0134] The resulting composite solid electrolyte membrane is denoted as Li2-PEO-LiTFSI.
[0135] Comparative Example 4
[0136] Based on the content disclosed in Example 1, the following modifications are made:
[0137] The immersion temperature is 90℃.
[0138] The resulting composite solid electrolyte membrane is denoted as Li3-PEO-LiTFSI.
[0139] Comparative Example 5
[0140] Based on the content disclosed in Example 1, the following modifications are made:
[0141] The vacuum drying temperature was 70℃, and the vacuum drying time was 120 min.
[0142] The resulting composite solid electrolyte membrane is denoted as Li4-PEO-LiTFSI.
[0143] Comparative Example 6
[0144] Based on the content disclosed in Example 1, the following modifications are made:
[0145] The vacuum drying temperature is 90℃, and the vacuum drying time is 60 minutes.
[0146] The resulting composite solid electrolyte membrane is denoted as Li5-PEO-LiTFSI.
[0147] Comparative Example 7
[0148] Based on the content disclosed in Example 1, the following modifications are made:
[0149] The hot pressing temperature is 40℃, and the hot pressing time is 2.0 min.
[0150] The pressure for hot pressing is 25 MPa.
[0151] The resulting composite solid electrolyte membrane is denoted as Li6-PEO-LiTFSI.
[0152] Comparative Example 8
[0153] Based on the content disclosed in Example 1, the following modifications are made:
[0154] The hot pressing temperature is 90℃, and the hot pressing time is 0.2min.
[0155] The pressure for hot pressing is 2 MPa.
[0156] The resulting composite solid electrolyte membrane is denoted as Li7-PEO-LiTFSI.
[0157] Relevant experimental and effect data:
[0158] The composite solid electrolyte membranes obtained in Example 1 and Comparative Example 1 were subjected to AC impedance testing, and the results are as follows: Figure 3 As shown, the results indicate that the impedance of the composite solid electrolyte membrane in Example 1 is 22Ω, while the impedance of the composite solid electrolyte membrane in Comparative Example 1 is 36Ω. Therefore, the impedance value in Example 1 is only 61% of the impedance value in the Comparative Example. The smaller the impedance value, the higher the ionic conductivity of the electrolyte.
[0159] The composite solid electrolyte membranes obtained in each embodiment and comparative example were cut using a film press to obtain circular membrane samples with a diameter of 16 mm. The thickness of each circular membrane sample was then measured using a thin film thickness gauge, and the results are shown in Table 1.
[0160] The impedance of the stainless steel blocking battery was then tested using the EIS method on the composite solid electrolyte membrane. The ionic conductivity of the membrane sample at 20°C was calculated using the following formula:
[0161] σ=L / (R*S),
[0162] In the formula, σ is the ionic conductivity;
[0163] L is the thickness of the electrolyte membrane;
[0164] R is the body impedance;
[0165] S represents the area of the solid electrolyte membrane.
[0166] The calculated ionic conductivity results based on the above formula are shown in Table 1.
[0167] Table 1. Membrane thickness and ionic conductivity of the composite solid electrolyte membranes in each embodiment and comparative example.
[0168]
[0169]
[0170] As shown in Table 1, the method for preparing a composite solid electrolyte membrane provided in this application uses polyethylene oxide and lithium carboxymethyl cellulose as raw materials to improve the ionic conductivity of the composite solid electrolyte membrane without adding organic solvents. Furthermore, adding a plasticizer to the raw materials can further improve the ionic conductivity of the composite solid electrolyte membrane. The use of the plasticizer also improves the plasticity of the mixture, facilitating subsequent hot-pressing to composite the solid electrolyte membrane, thus avoiding the use of large amounts of organic solvents. Therefore, this preparation method can increase the ionic conductivity of the composite solid electrolyte membrane to 1.50 × 10⁻⁶. -4 While improving the S / cm ratio, the environmental friendliness of the composite solid electrolyte membrane is also enhanced.
[0171] In addition, the method for preparing a composite solid electrolyte membrane provided in this application uses a hot-pressing dry processing technology, which uses only a very small amount of plasticizer. The overall process is greener, more environmentally friendly, and safer than the traditional solution casting method.
[0172] Furthermore, the composite solid electrolyte membrane provided in this application embodiment can improve its ionic conductivity to 1.50 × 10⁻⁶ by adding lithium carboxymethyl cellulose to the raw materials. -4 S / cm or higher.
[0173] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed in this application.
Claims
1. A method for preparing a composite solid electrolyte membrane, characterized in that, The preparation method includes: Polyethylene oxide, lithium carboxymethyl cellulose, and lithium salt are mixed to obtain a mixture; The mixture is impregnated with a plasticizer to induce a plasticizing reaction, thereby obtaining an impregnated mixture; The impregnation mixture is subjected to vacuum drying to remove excess plasticizer, thereby obtaining a solid electrolyte membrane raw material; The solid electrolyte membrane raw material is hot-pressed to obtain a composite solid electrolyte membrane; The weight m1 of the plasticizer and the weight m2 of the mixture satisfy the following relationship: m1:m2 = (0.9~1.1):1; The immersion temperature is 75℃~85℃, and the immersion time is ≥12h; The vacuum drying temperature is 75℃~85℃, and the vacuum drying time is 30min~120min; The hot pressing temperature is 50℃~80℃, the hot pressing time is 0.5min~1.5min, and the hot pressing pressure is 5MPa~20MPa.
2. The preparation method according to claim 1, characterized in that, The content of residual plasticizer in the solid electrolyte membrane raw material and the mass ratio of the solid electrolyte membrane raw material satisfy the following condition: residual plasticizer: solid electrolyte membrane raw material ≤ 0.
1.
3. The preparation method according to claim 1, characterized in that, The lithium salt includes at least one of the following: Lithium bis(trifluoromethanesulfonyl)imide, lithium perchlorate, lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate, lithium tetrafluoroborate, and lithium dioxalate borate.
4. The preparation method according to claim 1, characterized in that, The plasticizer includes at least one of the following: Ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate.
5. The preparation method according to claim 1, characterized in that, The weight m3 of the polyethylene oxide, the weight m4 of the lithium carboxymethyl cellulose, and the weight m5 of the lithium salt satisfy the following relationship: m3:m4:m5 = (4~7):(4~1):
2.
6. A composite solid electrolyte membrane, characterized in that, The composite solid electrolyte membrane is prepared by the preparation method according to any one of claims 1 to 5.
7. The composite solid electrolyte membrane according to claim 6, characterized in that, The thickness of the composite solid electrolyte membrane is 20 μm to 200 μm.