A PMMA-PCL-based composite solid electrolyte, its preparation method and application

Abstract

This invention provides a PMMA-PCL-based composite solid electrolyte, its preparation method, and its applications. The composite solid electrolyte comprises the following components: polymethyl methacrylate, polycaprolactone, lithium salt, active lithium-containing filler, and an unsaturated alkynyl compound with photoinduced secondary self-enhancing properties. This invention promotes supramolecular homogeneous integration within the electrolyte through magnetic field-microwave coupling and, for the first time, introduces an unsaturated alkynyl compound with photoinduced secondary self-enhancing properties to anchor solvent molecules and anions, thereby regulating the local coordination environment of lithium ions at the interface to improve lithium-ion transport and interfacial stability of the PMMA-PCL-based composite solid electrolyte at room temperature. This results in the PMMA-PCL-based composite solid electrolyte provided by this invention exhibiting excellent room-temperature performance and significantly improving the performance of symmetric cells at 0.1 mA cm⁻¹. ‑1 The time it takes for the current density to allow for stable cycling.

Description

Technical Field

[0001] This invention belongs to the field of energy storage materials technology, specifically relating to a PMMA-PCL-based composite solid electrolyte, its preparation method, and its application. Background Technology

[0002] With the rapid development of electric vehicles and large-scale energy storage systems, the demand for high-safety, high-energy-density lithium-ion batteries is becoming increasingly urgent. Traditional liquid electrolyte lithium-ion batteries suffer from problems such as easy leakage and flammability, and their energy density is limited (below 300 Wh / kg). At the same time, the growth of lithium dendrites in liquid electrolytes may cause short circuits and thermal runaway, posing serious safety hazards.

[0003] Solid-state electrolytes are the core component of all-solid-state batteries, requiring high ionic conductivity, good mechanical properties, and interfacial stability with electrode materials. Among various solid-state electrolytes, polymer solid-state electrolytes are considered one of the most promising technologies for industrialization due to their good flexibility, processability, and good interfacial contact with electrodes. Polymethyl methacrylate (PMMA)-based polymer electrolytes are an important type of material. The polar carbonyl groups (C=O) on their molecular chains can coordinate with lithium ions, promoting lithium salt dissociation. Furthermore, PMMA has a high dielectric constant (ε≈3.0-3.5), which also facilitates lithium salt dissociation. However, PMMA-based polymer electrolytes have low ionic conductivity at room temperature (typically below 10). -4 Furthermore, its mechanical strength is insufficient, making it difficult to effectively suppress lithium dendrite penetration. On the other hand, polycaprolactone (PCL), as a biodegradable aliphatic polyester material, possesses excellent flexibility and plasticity. Its molecular chain structure is soft, and its chain segment mobility is strong, which theoretically facilitates lithium-ion migration. However, PCL's room-temperature ionic conductivity is still very low, and its interfacial stability with the lithium metal anode is also poor.

[0004] Combining PMMA with PCL promises to leverage the high dielectric constant of PMMA and the flexibility of PCL, synergistically optimizing the ionic conductivity and mechanical properties of the electrolyte. However, novel PMMA-PCL-based electrolytes still face challenges such as low lithium-ion transference number, insufficient room-temperature conductivity, and high solid-solid interface impedance, leading to intensified polarization during battery cycling. Notably, lithium-ion transport within the novel PMMA-PCL matrix heavily relies on polymer chain movement, which is often limited by polymer crystallinity at room temperature, resulting in insufficient ionic conductivity for rapid charge-discharge operations. Furthermore, the interface between the electrolyte and the lithium metal anode is unstable, easily forming lithium dendrites and side reaction layers, impacting battery cycle life and safety performance.

[0005] To overcome these challenges, current research typically employs the addition of inorganic active lithium-containing fillers (such as LLZO (lithium lanthanum zirconium oxide) and LATP (lithium oxyphosphine sulfate)) to construct rapid ion transport channels, or the introduction of plasticizers (such as succinic acid) to reduce crystallinity and improve chain segment mobility. However, these methods still have limitations. For example, inorganic fillers tend to aggregate in novel PMMA-PCL matrices, affecting the uniformity of ionic conductivity; and the addition of liquid plasticizers may sacrifice the mechanical strength of the electrolyte and introduce safety hazards. Therefore, developing novel composite solid electrolytes and overcoming the mechanical property losses and dispersion inhomogeneities induced by spontaneous phase separation during composite electrolyte preparation is particularly important. Synergistic optimization of the preparation process and molecular design to regulate the supramolecular chemistry of the electrolyte and the local coordination environment of lithium ions, and to enhance interfacial stability, are key to improving cycle life and safety performance. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a PMMA-PCL-based composite solid electrolyte, its preparation method, and its applications. The composite solid electrolyte of this invention comprises the following components: polymethyl methacrylate (PMMA), polycaprolactone (PCL), lithium salt, active lithium-containing filler, and an unsaturated alkynyl compound with photoinduced secondary self-enhancing properties. The PMMA-PCL-based composite solid electrolyte provided by this invention is prepared using a magnetic field-microwave coupled assisted synthesis method. This method promotes the homogeneous integration of supramolecular components within the electrolyte through magnetic field-microwave coupling, and for the first time introduces an unsaturated alkynyl compound with photoinduced secondary self-enhancing properties to anchor solvent molecules and anions, thereby regulating the local coordination environment of lithium ions at the interface to improve lithium-ion transport and interfacial stability of the PMMA-PCL-based composite solid electrolyte at room temperature. This results in the PMMA-PCL-based composite solid electrolyte provided by this invention exhibiting excellent room temperature performance and significantly improving the performance of symmetric cells at 0.1 mA cm⁻¹. -1 The time it takes for the current density to allow for stable cycling.

[0007] This invention provides a PMMA-PCL-based composite solid electrolyte comprising the following components: polymethyl methacrylate (PMMA), polycaprolactone (PCL), lithium salt, active lithium-containing filler, and an unsaturated alkyne compound with photoinduced secondary self-reinforcing properties; wherein the photoinduced secondary self-reinforcing alkyne compound contains unsaturated alkyne sites.

[0008] Furthermore, the mass ratio of polycaprolactone (PCL) to polymethyl methacrylate (PMMA) is 1:(1-8); the mass ratio of polymethyl methacrylate to lithium salt is (2-15):1; the amount of active lithium-containing filler is 1%-50% of the total mass of polymethyl methacrylate and polycaprolactone; and the amount of unsaturated alkynyl compound is 2%-50% of the total mass of polymethyl methacrylate and polycaprolactone.

[0009] Preferably, the unsaturated alkynyl compounds include: α,ω-diynyl polyethylene glycol, 5-dodecyne, propargylamine, 3',6'-dihydroxy-3-oxo-N-(prop-2-yn-1-yl)-3H-spiro[isobenzofuran-1,9'-oxazanthene]-5-carboxamide, propargyl ether, 17α-ethynyltestosterone, propargyl butylcarbamate, 2-(prop-2-yn-1-yloxy)ethyl acrylate, N-(tert-butoxycarbonyl)-L-propargylglycine, propargyl PEG3-MS, 7-tetradecyne, 6-dodecyne, At least one of the following: propargyl-PEG2-amine, propargyl sulfonate sodium, tert-butoxycarbonyl-D-propargylglycine, ethyl propargyl ester, 18-methylnorethindrone, methyl propargyl ether, propargyl ester, propargylamine hydrochloride, 4-(triisopropylsilynyl)benzyne, L-propargylglycine, propargyl phosphate, tert-butyl 2-propenylcarbamate, propargyl acrylate, 2-aminopent-4-ynylate maleimide, propargyl ether, 1-hexene-5-yne, 4-hydroxybenzyne, 9-ynylanthracene, 1-propargylpiperidine, phenylpropargyl ether, and propargylamine.

[0010] More preferably, the unsaturated alkynyl compound is selected from at least one of methyl propargyl ether, phenyl propargyl ether, clodinafop-propargyl ester, triargyl phosphate, propargyl butylcarbamate, and propargyl acrylate, especially phenyl propargyl ether and triargyl phosphate. The phenyl propargyl ether and triargyl phosphate have stable organic coordinating groups, exhibit photoinduced secondary self-enhancing effects, and the organic coordinating groups have active sites for regulating lithium-ion transport. During lithium symmetric half-cell cycling, they can participate in the coordination environment of lithium ions and PMMA-PCL, which is beneficial for improving lithium-ion conductivity, lithium metal interface stability, and increasing the cycle time of all-solid-state lithium metal batteries at room temperature.

[0011] Preferably, the amount of the unsaturated alkynyl compound is 5% to 25% of the total mass of polymethyl methacrylate and polycaprolactone; more preferably, it is 10% to 20%.

[0012] Preferably, the lithium salt is at least one selected from LiOTF (lithium trifluoromethanesulfonate), LiBF4, LiTFSI (lithium bis(trifluoromethanesulfonyl)imide), LiFSI (lithium bis(fluorosulfonyl)imide), LiDFOB (lithium difluorooxalate borate), LiPF6, LiPO2F2, LiClO4, LiNO3, and LiAsF6. Preferably, the mass ratio of polymethyl methacrylate to lithium salt is (4–12):1; more preferably, it is (4–8):1.

[0013] Preferably, the active lithium-containing filler comprises at least one of lithium lanthanum zirconium oxide (LLZO), lithium lanthanum zirconium tantalum oxide (LLZTO), lithium lanthanum zirconium niobium tantalum oxide (LLZTNO), lithium aluminum titanium phosphide (LATP), lithium phosphorus sulfide chloride (LPSCl), lithium indium chloride (Li3InCl6), lithium ytterbium chloride (Li3YCl6), lithium zirconate (Li2ZrO3), and lithium phosphorus oxynitrogen (LiPON). Preferably, the mass of the active lithium-containing filler is 5%–30% of the mass of polymethyl methacrylate and polycaprolactone; more preferably, it is 10%–20%.

[0014] Preferably, the mass ratio of polycaprolactone (PCL) to polymethyl methacrylate (PMMA) is 1:(1-6); more preferably, it is 1:(1-5).

[0015] The present invention also provides a method for preparing PMMA-PCL-based composite solid electrolyte, characterized in that: each component of the solid electrolyte raw material is taken, a solvent is added, and the mixture is stirred and mixed evenly under magnetic field-microwave coupling assisted process; after obtaining a uniform slurry, it is vacuum dried, and the dried electrolyte membrane is irradiated under ultraviolet light for 10-15 hours to induce secondary self-reinforcement of alkynyl compounds, thereby obtaining PMMA-PCL-based composite solid electrolyte.

[0016] Furthermore, the polymethyl methacrylate (PMMA) is dried before use. The drying process is as follows: drying at 30-100°C for 8-30 hours, preferably at 45-60°C for 10-15 hours.

[0017] Preferably, the solvent is at least one selected from anhydrous acetonitrile, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), and N,N-dimethylacetamide (DMAC).

[0018] Preferably, the magnetic field-microwave coupling assisted process is as follows: the entire mixing process is carried out under microwave (preferably 2.45 GHz). The mixing process involves heating and stirring at 30–80°C for 8–40 hours; more preferably, heating and stirring at 45–70°C for 12–24 hours. During the stirring process, magnetic field (preferably 1 T) coupling-assisted dispersion is performed every hour, preferably for 10–50 minutes, more preferably for 20–40 minutes, to obtain a supramolecular homogenized and linked slurry.

[0019] Preferably, the vacuum drying process is as follows: vacuum drying at 50-100°C for 8-72 hours; more preferably, vacuum drying at 60-80°C for 12-36 hours; even more preferably, vacuum drying at 65-75°C for 20-30 hours, followed by natural drying under an argon atmosphere for 6-8 hours.

[0020] This invention also provides the application of the above-mentioned PMMA-PCL-based composite solid electrolyte in the preparation of all-solid-state lithium batteries.

[0021] The present invention provides an all-solid-state lithium battery that operates stably at room temperature, comprising the above-mentioned PMMA-PCL-based composite solid electrolyte.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. This invention introduces unsaturated alkyne sites with photoinduced secondary self-reinforcing properties into a polymethyl methacrylate-polycaprolactone (PMMA-PCL) based composite solid electrolyte, optimizing the local coordination structure of lithium ions and PMMA-PCL polymer segments, thereby significantly promoting lithium salt dissociation and reduction at the electrode-electrolyte interface. This coordination structure at the interface promotes the complete decomposition of the lithium salt and unsaturated alkyne compound coordinating groups, forming high-energy interface products such as LiF that effectively suppress lithium dendrite formation. This results in a significantly improved ionic conductivity, high critical current density, and lithium stability of the solid electrolyte at room temperature. Furthermore, by controlling the amounts of polycaprolactone (PCL), lithium salt, active lithium-containing filler, and unsaturated alkyne compound added to polymethyl methacrylate (PMMA), the lithium-ion conductivity and interface stability can be regulated. This novel PMMA-PCL based polymer solid electrolyte provides novel properties, low interface impedance, and significantly improved lithium metal symmetric battery performance at room temperature (0.1 mA cm⁻¹). -1 The time it takes for the current density to allow for stable cycling.

[0024] 2. The composite solid electrolyte preparation method provided by the present invention promotes the homogeneous integration of supramolecular molecules within the PMMA-PCL-based composite solid electrolyte through a magnetic field-microwave coupled auxiliary process, inhibits phase separation of the two polymer chains, loosens the polymer chains and active lithium-containing fillers, and enables photo-induced secondary self-reinforcement after film formation, thus breaking its performance limit. Attached Figure Description

[0025] Figure 1 Impedance diagram and ionic conductivity of PMMA-PCL-based composite solid electrolyte prepared in Example 1;

[0026] Figure 2 Cyclic performance diagram of a symmetrical battery assembled with a PMMA-PCL-based composite solid electrolyte prepared in Example 1;

[0027] Figure 3 Impedance diagram and ionic conductivity of PMMA-PCL-based composite solid electrolyte prepared in Example 2;

[0028] Figure 4 Cyclic performance diagram of a symmetric battery assembled with a PMMA-PCL-based composite solid electrolyte prepared in Example 2;

[0029] Figure 5 Impedance diagram and ionic conductivity of PMMA-PCL-based composite solid electrolyte prepared in Example 3;

[0030] Figure 6 : Cyclic performance diagram of the symmetric battery assembled with the PMMA-PCL-based composite solid electrolyte prepared in Example 3;

[0031] Figure 7 Impedance diagram and ionic conductivity of PMMA-PCL-based composite solid electrolyte prepared in Example 4;

[0032] Figure 8 Cyclic performance diagram of a symmetric battery assembled with a PMMA-PCL-based composite solid electrolyte prepared in Example 4;

[0033] Figure 9 Impedance diagram and ionic conductivity of PMMA-PCL-based composite solid electrolyte prepared in Example 5;

[0034] Figure 10 Cyclic performance diagram of a symmetric battery assembled with a PMMA-PCL-based composite solid electrolyte prepared in Example 5;

[0035] Figure 11 Impedance diagram and ionic conductivity of PMMA-PCL-based composite solid electrolyte prepared in Example 6;

[0036] Figure 12Cyclic performance diagram of the symmetric battery assembled from the PMMA-PCL-based composite solid electrolyte prepared in Example 6.

[0037] Figure 13 Impedance diagram and ionic conductivity of PMMA-PCL-based composite solid electrolyte prepared in Comparative Example 1;

[0038] Figure 14 Cyclic performance of a symmetric battery assembled from a PMMA-PCL-based composite solid electrolyte prepared in Comparative Example 1. Detailed Implementation

[0039] To enable those skilled in the art to better understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention. Unless otherwise specified, the raw materials, reagents, or apparatus used in the following embodiments and comparative examples can be obtained from conventional commercial sources or by existing known methods. Polymethyl methacrylate (PMMA) is dried before use at 45–60°C for 10–15 hours. In the following embodiments, the vacuum drying in step (3) is performed at 60–80°C for 12–36 hours.

[0040] The specific method for testing room-temperature ionic conductivity is as follows: A stainless steel sheet is used as the blocking electrode. The prepared solid electrolyte membrane is assembled into a blocking battery, and the battery is placed at room temperature for 2 hours. The impedance R of the blocking battery is measured using electrochemical impedance spectroscopy. The thickness L of the solid electrolyte membrane is measured using a thickness gauge, and the diameter of the solid electrolyte membrane is measured using a standard ruler. The area S is calculated, and the result obtained based on the formula L / RS is the room-temperature ionic conductivity.

[0041] Assemble a 0.1 mA cm-scale lithium symmetric half-cell. -1 The specific test method for stable cycle time at current density: A lithium symmetric half-cell is assembled using lithium metal as both positive and negative electrodes. A constant current charge-discharge test is performed using a battery testing system, with the current set at 0.1 mA cm⁻¹. -1 The charge-discharge time was 1 hour, and the cycle curve and stable cycle time of the symmetrical half-cell were finally obtained.

[0042] Example 1:

[0043] (1) Weigh 4.8g PMMA and 0.6g PCL and set aside;

[0044] (2) Dissolve 0.3g LiTFSI in anhydrous acetonitrile solvent; then stir at 300 r / min for 15 min at room temperature to obtain a solution; then add 1.08g methylpropargyl ether and stir for 15 min; after the methylpropargyl ether is completely dissolved, add 1.08g LLZTO and continue stirring at 300 r / min.

[0045] (3) The weighed PMMA and PCL were then slowly dispersed and dissolved in the solution. The mixture was stirred at 300 r / min at 60 °C under microwave (2.45 GHz) conditions for 24 hours. Every hour, the slurry was placed in a 1T parallel magnetic field for 10 minutes to obtain a uniform slurry. The slurry was then vacuum dried to obtain the polymer electrolyte membrane. The dried electrolyte membrane was then subjected to a 350 nm, 90 μW / cm 2 Irradiation under ultraviolet light for 12 hours induced secondary self-reinforcement of the alkynyl compound, yielding a PMMA-PCL-based composite solid electrolyte. Its room temperature ionic conductivity was 0.21 mS / cm. -1 (like Figure 1 Assemble a 0.1 mA cm lithium symmetric half-cell. -1 It can be stably cycled for 400 hours at current density (e.g.) Figure 2 ).

[0046] Example 2:

[0047] (1) Weigh 2.4g PMMA and 0.4g PCL and set aside;

[0048] (2) Dissolve 0.3g LiFSI in dimethylformamide solvent; then stir the mixture at 320 r / min for 10 min at room temperature to obtain a solution; then add 0.42g clodinafop-propargyl and stir for 8 min; after it is completely dissolved, add 0.42g LLZTO and continue stirring at 300 r / min.

[0049] (3) The weighed PMMA and PCL were slowly dispersed and dissolved in the solution, and then stirred at 320 r / min at 80 °C and microwave (2.45 GHz) for 8 hours. Every hour, the slurry was placed in a 1T parallel magnetic field for 40 minutes to obtain a uniform slurry. Then, the slurry was vacuum dried to obtain a polymer electrolyte membrane. The dried electrolyte membrane was then subjected to a 350 nm, 90 μW / cm 2 Irradiation under ultraviolet light for 12 hours induced secondary self-reinforcement of the alkynyl compound, yielding a PMMA-PCL-based composite solid electrolyte. Its room temperature ionic conductivity was 0.32 mS / cm. -1 (like Figure 3 Assemble lithium symmetric half-cells at 0.1 mA cm⁻¹ -1Stable cycling for 572 hours at current density (e.g.) Figure 4 ).

[0050] Example 3:

[0051] (1) Weigh 1.2g PMMA and 0.3g PCL and set aside;

[0052] (2) Dissolve 0.2g LiTFSI in N-methylpyrrolidone (NMP); then stir the mixture at 350r / min for 25min at room temperature to obtain a solution; then add 0.15g propargyl butylcarbamate and stir for 30min; after propargyl butylcarbamate is completely dissolved, add 0.15g LLZTO and continue stirring at 300r / min.

[0053] (3) The weighed PCL and PMMA were slowly dispersed and dissolved in the solution, and then stirred at 320 r / min at 70 °C and microwave (2.45 GHz) for 20 hours. Every hour, the slurry was placed in a 1T parallel magnetic field for 15 minutes to obtain a uniform slurry. Then, the slurry was vacuum dried to obtain a polymer electrolyte membrane. The dried electrolyte membrane was then subjected to a 350 nm, 90 μW / cm 2 Irradiation under ultraviolet light for 12 hours induced secondary self-reinforcement of the alkynyl compound, yielding a PMMA-PCL-based composite solid electrolyte. Its room temperature ionic conductivity was 0.37 mS / cm. -1 (like Figure 5 Assemble lithium symmetric half-cells at 0.1 mA cm⁻¹ -1 Stable cycling for 612 hours at current density (e.g.) Figure 6 ).

[0054] Example 4:

[0055] (1) Weigh 0.9g PMMA and 0.3g PCL and set aside;

[0056] (2) Dissolve 0.225g LiTFSI in DMSO solvent; then stir the mixture at 250r / min for 40min at room temperature to obtain a solution; then add 0.24g propargyl acrylate and stir for 30min; after the propargyl acrylate is completely dissolved, add 0.24g LLZO and stir continuously at 400r / min.

[0057] (3) The weighed PCL and PMMA were slowly dispersed and dissolved in the solution, and then stirred at 400 r / min at 45℃ and microwave (2.45 GHz) for 18 hours. Every hour, the slurry was placed in a 1T parallel magnetic field for 15 minutes to obtain a uniform slurry. Then, the slurry was vacuum dried to obtain a polymer electrolyte membrane. The dried electrolyte membrane was then subjected to a 350 nm, 90 μW / cm 2 Irradiation under ultraviolet light for 12 hours induced secondary self-reinforcement of the alkynyl compound, yielding a PMMA-PCL-based composite solid electrolyte. Its room temperature ionic conductivity was 0.42 mS / cm. -1 (like Figure 7 Assemble lithium symmetric half-cells at 0.1 mA cm⁻¹ -1 Stable cycling for 800 h at current density ( Figure 8 ).

[0058] Example 5:

[0059] (1) Weigh 1.5g PMMA and 0.75g PCL and set aside;

[0060] (2) Dissolve 0.75g LiTFSI in N,N-dimethylacetamide (DMAC) solvent; then stir the mixture at 300r / min for 15min at room temperature to obtain a solution; then add 0.27g phenylpropynyl ether and stir for 20min; after the phenylpropynyl ether is completely dissolved, add 0.18g LLZTO and continue stirring at 300r / min.

[0061] (3) The weighed PCL and PMMA were slowly dispersed and dissolved in the solution, and then stirred at 320 r / min at 60 °C and microwave (2.45 GHz) for 40 hours. Every hour, the slurry was placed in a 1T parallel magnetic field for 25 minutes to obtain a uniform slurry. Then, the slurry was vacuum dried to obtain a polymer electrolyte membrane. The dried electrolyte membrane was then subjected to a 350 nm, 90 μW / cm 2 Irradiation under ultraviolet light for 12 hours induced secondary self-reinforcement of the alkynyl compound, yielding a PMMA-PCL-based composite solid electrolyte. Its room temperature ionic conductivity was 0.47 mS / cm. -1 (like Figure 9 Assemble lithium symmetric half-cells at 0.1 mA cm⁻¹ -1 Stable cycling for 700 hours at current density (e.g.) Figure 10 ).

[0062] Example 6:

[0063] (1) Weigh 1.6g PMMA and 1.6g PCL and set aside;

[0064] (2) Dissolve 1.6g LiTFSI in DMF solvent; then stir the mixture at 450r / min for 10min at room temperature to obtain a clear solution; then add 0.16g triargyl phosphate and stir for 10min; after the triargyl phosphate is completely dissolved, add 0.16g LLZTO and stir continuously at 280r / min.

[0065] (3) The weighed PCL and PMMA were slowly dispersed and dissolved in the solution, and then stirred at 200 r / min at 50 °C and microwave (2.45 GHz) for 24 hours. Every hour, the slurry was placed in a 1T parallel magnetic field for 30 minutes to obtain a uniform slurry. After obtaining the uniform slurry, it was vacuum dried to obtain a polymer electrolyte membrane. The dried electrolyte membrane was irradiated under a UV lamp for 12 h to induce secondary self-reinforcement of the alkyne compound, thus obtaining a PMMA-PCL-based composite solid electrolyte. Its room temperature ionic conductivity is 0.63 mS / cm. -1 (like Figure 11 Assemble lithium symmetric half-cells at 0.1 mA cm⁻¹ -1 It can be stably cycled for 1170 hours at current density (e.g.) Figure 12 ).

[0066] Comparative Example 1:

[0067] (1) Weigh 1.6g PMMA and 0.4g PCL and set aside;

[0068] (2) Dissolve 0.2g LiTFSI in DMAC solvent; then stir the mixture at 200 r / min for 15 minutes at room temperature to obtain a clear solution; then add 0.2g LLZTO and disperse it in the above solution, and continue stirring at 250 r / min.

[0069] (2) Weighed PCL and PMMA were slowly dispersed and dissolved in the solution, and then stirred at 250 r / min at 60℃ for 24 hours without any auxiliary stirring to obtain a well mixed slurry. After drying, no secondary self-reinforcement was performed to obtain a PMMA-PCL-based composite solid electrolyte. Its room temperature ionic conductivity is 0.11 mS / cm. -1 (like Figure 13 Assemble lithium symmetric half-cells at 0.1 mA cm⁻¹ -1 It can be stably cycled for 350 hours at current density (e.g.) Figure 14 ).

[0070] As can be seen from Comparative Example 1, the novel PMMA-PCL solid electrolyte proposed in this invention can operate stably at room temperature and has the potential to assemble all-solid-state batteries that operate reliably at room temperature. Furthermore, a comparison between Examples 1-6 and Comparative Example 1 reveals that the PMMA-PCL-based composite solid electrolytes prepared in Examples 1-6 using unsaturated alkyne compounds with photoinduced secondary self-enhancing properties and a magnetic field-microwave coupling assisted process can significantly further improve the room temperature lithium-ion conductivity. Under the same PMMA and PCL ratio, due to the use of propargyl butylcarbamate additive and the magnetic field-microwave coupling assisted process, the room temperature ionic conductivity of the novel PMMA-PCL electrolyte in Example 3 is 0.37 mS / cm. -1 This is significantly higher than the 0.11 mS / cm of Comparative Example 1. -1 Furthermore, the modification measures can significantly improve the symmetric cell's efficiency at 0.1 mA cm⁻¹ at room temperature. -1 Current density stabilizes cycling time, enhances stability against lithium metal, and suppresses lithium dendrite formation. Example 3: Assembled lithium symmetric half-cell at 0.1 mA cm⁻¹ -1 It can cycle stably for 612 hours at the current density, which is much higher than the 350 hours of Comparative Example 1. Furthermore, a comparison between Examples 1-6 reveals that different alkyne compounds can all improve ionic conductivity and lithium metal stability, but their effects differ. The PMMA-PCL electrolyte using propargyl phosphate in Example 6 exhibits the highest ionic conductivity, reaching 0.63 mS / cm. -1 And assembled a lithium symmetric half-cell at 0.1 mA cm⁻¹ -1 It can be stably cycled for 1170 hours at the current density, exhibiting the longest stable cycle time. Furthermore, as can be seen from Examples 1-6, with the increase of PCL content in the PMMA and PCL ratio, its room-temperature lithium-ion conductivity gradually increases, reaching 0.1 mA cm⁻¹. -1 The stable cycle time increases under current density.

[0071] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of protection of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A PMMA-PCL-based composite solid electrolyte, characterized in that it comprises the following components: polymethyl methacrylate, polycaprolactone, lithium salt, active lithium-containing filler and unsaturated alkyne compound with photo-induced secondary self-enhancement property; the unsaturated alkyne compound with photo-induced secondary self-enhancement property contains unsaturated alkyne sites. The unsaturated alkyne compound is at least one of α, ω-dialkyne polyethylene glycol, 5-dodecyne, propargylamine, 3', 6'-dihydroxy-3-oxo-N-(prop-2-yn-1-yl)-3H-spiro[isobenzoxazol-1, 9'-xanthene]-5-formamide, propargyl ether, 17α-ethinyltestosterone, propargyl butyl carbamate, 2-(prop-2-yn-1-yloxy)ethyl acrylate, N-(tert-butoxycarbonyl)-L-propargylglycine, propargyl PEG3-MS, 7-tetradecyne, 6-dodecyne, propargyl-PEG2-amine, sodium propargyl sulfonate, tert-butoxycarbonyl-D-propargylglycine, ethyl propiolate, 18-methyl norethindrone, methyl propargyl ether, clomazone, propargylamine hydrochloride, 4-(triisopropylsilyl)benzene, L-propargylglycine, tripropargyl phosphate, propargyl acrylate, 2-aminopent-4-yne maleimide, 1-hexene-5-yne, 4-hydroxybenzene, 9-alkynyl anthracene, 1-propargylpiperidine, phenyl propargyl ether and tripropargyl amine. The active lithium-containing filler is at least one of lithium lanthanum zirconium oxide, lithium lanthanum zirconium tantalum oxide, lithium lanthanum zirconium niobium tantalum oxide, lithium aluminum titanium phosphorus, lithium phosphorus sulfur chloride, lithium indium chloride, lithium ytterbium chloride, lithium zirconate and lithium phosphorus oxygen nitrogen. The preparation method of the PMMA-PCL-based composite solid electrolyte comprises the following steps: taking each component of solid electrolyte raw material, adding a solvent, stirring and mixing uniformly under the assistance of a magnetic field-microwave coupling process, vacuum drying the obtained uniform slurry, irradiating the dried electrolyte film under a violet light for 10-15 hours to induce secondary self-enhancement of the alkyne compound, and obtaining the PMMA-PCL-based composite solid electrolyte; the magnetic field-microwave coupling process is that the whole mixing process is carried out under microwaves; the mixing process is heated and stirred at 30-80℃ for 8-40 hours; and the stirring process is assisted by magnetic field coupling and dispersion every 1 hour.

2. The PMMA-PCL based composite solid-state electrolyte of claim 1, wherein, The mass ratio of polycaprolactone to polymethyl methacrylate is 1: (1-8) ; the mass ratio of polymethyl methacrylate to lithium salt is (2-15) : 1; the amount of the active lithium-containing filler is 1%-50% of the total mass of polymethyl methacrylate and polycaprolactone; and the amount of the unsaturated alkyne compound is 2%-50% of the total mass of polymethyl methacrylate and polycaprolactone.

3. The PMMA-PCL based composite solid-state electrolyte of claim 1, wherein, The lithium salt is at least one of LiOTF, LiBF4, LiTFSI, LiFSI, LiDFOB, LiPF6, LiPO2F2, LiClO4, LiNO3 and LiAsF6.

4. The PMMA-PCL based composite solid-state electrolyte of claim 1, wherein, The solvent used in the preparation method is at least one of anhydrous acetonitrile, N, N-dimethylformamide, dimethyl sulfoxide, N-methyl pyrrolidone and N, N-dimethylacetamide.

5. Use of the PMMA-PCL based composite solid state electrolyte of any one of claims 1-4 in the manufacture of an all-solid-state lithium battery.

6. A solid-state lithium battery which is stable at room temperature, characterized by comprising the PMMA-PCL based composite solid state electrolyte of any one of claims 1-4.

Images