A tte-based solid-state electrolyte based on in-situ polymerization and a preparation method thereof
By in-situ polymerization and material blending, a TTE-based solid electrolyte with high mechanical strength and high ionic conductivity was prepared, which solved the problems of easy crystallization and flammability of polyoxyethylene electrolytes at room temperature, and achieved high energy density and safety of all-solid-state lithium metal batteries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NORTHWESTERN POLYTECHNICAL UNIV
- Filing Date
- 2026-04-22
- Publication Date
- 2026-06-23
AI Technical Summary
Polyethylene oxide solid electrolytes are prone to crystallization at room temperature, resulting in low ionic conductivity, making them unsuitable for high-voltage cathodes. They also lack mechanical strength, making them susceptible to penetration by lithium dendrites, and are flammable, thus failing to meet the application requirements of all-solid-state lithium metal batteries.
By employing an in-situ polymerization method, materials such as nanocellulose, phosphazene, perfluoropolyether, and trimethylolpropane triglycidyl ether are blended to form a TTE-based solid electrolyte with high mechanical strength and high ionic conductivity. The safety and performance of the electrolyte are improved through the synergistic effect of the nanocellulose support layer and the flame retardant effect of phosphazene.
An ultrathin, high mechanical strength, and high ionic conductivity TTE-based solid electrolyte was prepared, which can be matched with the high energy density NCM811 cathode, has excellent safety performance, prevents lithium dendrite puncture and combustion risks, and is suitable for large-scale industrial production.
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Figure CN122068111B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of solid electrolyte technology, and in particular to a TTE-based solid electrolyte based on in-situ polymerization and its preparation method. Background Technology
[0002] Lithium metal possesses the lowest electrochemical reduction potential (-3.04 V vs. SHE) and an extremely high theoretical specific capacity (3860 mAh g). -1 Lithium metal anodes are crucial for achieving next-generation high-energy-density batteries. However, the combination of traditional liquid organic electrolyte systems with highly active lithium metal anodes presents significant safety risks, including flammability, leakage, and the risk of thermal runaway or even explosion due to lithium dendrite growth. Using solid-state electrolytes (SSEs) to replace liquid electrolytes and matching them with lithium metal anodes is widely recognized as a fundamental way to simultaneously improve battery energy density and safety. Among various solid-state electrolytes, polymer solid-state electrolytes (SPEs) exhibit great application potential due to their excellent flexibility, lightweight, good interfacial contact, and ease of large-scale processing (such as casting and roll-to-roll processes). Polyethylene oxide (PEO) solid-state electrolytes, in particular, have become one of the most widely studied polymer electrolyte systems for lithium metal batteries due to their excellent solubility of lithium salts (such as LiTFSI and LiClO4) by the ether oxygen bond (-CH2-CH2-O-), relatively good interfacial compatibility with lithium metal, mature processing foundation, and ease of polymerization between epoxy groups.
[0003] Nevertheless, polyoxyethylene solid electrolytes still face significant challenges when applied to room-temperature lithium metal batteries: the polyoxyethylene segments are prone to crystallization at room temperature, severely hindering the development of lithium metal. + The migration of these molecules results in a generally low room-temperature ionic conductivity (typically below 10). -7 Up to 10 -8 Scm -1 The voltage level (on the order of magnitude) is insufficient to meet practical application requirements. The ether oxygen bond (-COC-) is easily oxidized and decomposed at voltages >3.8V, making it unsuitable for high-voltage cathodes. Furthermore, the relatively weak mechanical strength of the trimethylolpropane triglycidyl ether (TTE) matrix makes it difficult to effectively prevent dendrite penetration, ultimately leading to internal short-circuit failure of the battery. In addition, TTE is more prone to combustion when exposed to open flames, causing even more severe damage. Summary of the Invention
[0004] The purpose of this invention is to provide a TTE-based solid electrolyte based on in-situ polymerization and its preparation method. Through the synergistic effect of TTE in-situ polymerization, perfluoropolyether modification, phosphazene flame retardancy, and nanocellulose reinforcement, a TTE-based solid electrolyte with high mechanical strength, high ionic conductivity, high decomposition voltage, and ultra-thin flame retardancy is successfully prepared. This electrolyte not only solves many defects of existing TTE-based solid electrolytes, but also has a simple and controllable preparation process, making it suitable for large-scale industrial production and showing broad application prospects in the field of all-solid-state lithium metal batteries.
[0005] To achieve the above objectives, this invention provides a method for preparing a TTE-based solid electrolyte based on in-situ polymerization, comprising the following steps:
[0006] S1. Disperse nanocellulose in water and ultrasonically disperse to form a uniform nanocellulose dispersion.
[0007] S2. The nanocellulose dispersion was vacuum filtered and then dried to obtain the nanocellulose support layer.
[0008] S3. Phosphazene, trimethylolpropane triglycidyl ether, perfluoropolyether, lithium bis(trifluoromethanesulfonylimide) and lithium dioxalate borate are stirred and mixed to obtain TTE-based solid electrolyte slurry.
[0009] S4. The TTE-based solid electrolyte slurry obtained in S3 is coated onto the nanocellulose support layer obtained in S2, and an in-situ polymerization reaction is carried out in an oven. After the reaction is completed, a TTE-based solid electrolyte copolymerized from phosphazene, perfluoropolyether and trimethylolpropane triglycidyl ether is obtained.
[0010] Preferably, in S1, the ultrasonic dispersion power is 800W and the ultrasonic dispersion time is 30-60min.
[0011] Preferably, in step S3, the mixing temperature is 60-70℃ and the mixing time is 6-8h.
[0012] Preferably, in S3, the mass ratio of trimethylolpropane triglycidyl ether, lithium bis(trifluoromethanesulfonyl)imide, and lithium dioxalate borate is 40:10:1.
[0013] Preferably, in S3, the perfluoropolyether is 5%-15% of the total mass of trimethylolpropane triglycidyl ether, lithium bis(trifluoromethanesulfonyl)imide, and lithium dioxalate borate.
[0014] Preferably, in S3, the phosphazene is 15%-20% of the total mass of trimethylolpropane triglycidyl ether, lithium bis(trifluoromethanesulfonyl)imide, and lithium dioxalate borate.
[0015] Preferably, in S4, the thickness of the nanocellulose support layer is 10-20 μm.
[0016] Preferably, in S4, the coating thickness of the TTE-based solid electrolyte slurry is 50-100 μm.
[0017] Preferably, in S4, the oven temperature is 60-80℃, and the in-situ polymerization reaction time is 16-24h.
[0018] A TTE-based solid electrolyte based on in-situ polymerization, wherein the TTE-based solid electrolyte is prepared by the above-described method for preparing a TTE-based solid electrolyte based on in-situ polymerization.
[0019] Therefore, the present invention employs the above-mentioned TTE-based solid electrolyte based on in-situ polymerization and its preparation method, which has the following beneficial effects:
[0020] (1) In this invention, trimethylolpropane triglycidyl ether (TTE) has high ionic conductivity and initial fluidity. Through in-situ polymerization, a cross-linked network is formed, which effectively destroys the orderliness of polymer chain segments, reduces the crystallinity of polymer, and thus improves the ionic conductivity of TTE-based solid electrolyte. Nanocellulose effectively improves the ion transference number of TTE-based solid electrolyte and serves as a support layer. Through a simple in-situ polymerization process, an ultrathin TTE-based solid electrolyte with high mechanical strength, high ionic conductivity and high ion transference number is prepared.
[0021] (2) The decomposition voltage of the TTE-based solid electrolyte of the present invention is a key factor that hinders the realization of high energy density. Perfluoropolyether contains a large number of CF groups and has extremely high oxidation resistance. During the cycling process, a stable CEI layer can be constructed on the cathode surface, which significantly improves the decomposition voltage of the solid electrolyte so that it can match the NCM811 cathode with a higher working voltage, which is beneficial to improving the energy density of the all-solid-state lithium metal battery.
[0022] (3) Uneven deposition at the lithium metal anode interface can lead to the growth of lithium dendrites. During cycling, the growing lithium dendrites may puncture the separator, causing a short circuit in the battery and posing a risk of fire. This invention uses nanocellulose as a support layer to improve the mechanical strength of the solid electrolyte. At the same time, the introduction of phosphazene can decompose and release phosphorus-containing free radicals when the solid electrolyte is heated, capturing and neutralizing a large number of key hydrogen free radicals (H•) and hydroxyl free radicals (OH•) in the combustion chain reaction, thus interrupting combustion. In addition, the phosphorus-containing substances produced after the decomposition of BGCP can promote the formation of a dense and stable carbon layer on the surface of the support layer. This carbon layer can insulate against heat, isolate oxygen, and prevent the internal combustible substances from continuing to decompose. The synergistic effect of these two points makes the assembled full battery have high energy density and excellent safety performance.
[0023] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description
[0024] Figure 1 This is a comparison of stress-strain curves of the TTE-based solid electrolytes prepared in Examples 1-3 and Comparative Examples 1-2 of the present invention;
[0025] Figure 2 This is a comparison chart of the ionic conductivity of the TTE-based solid electrolytes prepared in Examples 1-3 and Comparative Examples 1-2 of this invention;
[0026] Figure 3 This is a comparison chart of the decomposition voltages of the TTE-based solid electrolytes prepared in Example 1 and Comparative Examples 1-2 of the present invention;
[0027] Figure 4 This is a comparison chart of the critical current densities of the TTE-based solid electrolytes prepared in Example 1 and Comparative Examples 1-2 of the present invention;
[0028] Figure 5 This is a comparison of the charge-discharge curves of the TTE-based solid electrolytes prepared in Example 1 and Comparative Examples 1-2 of the present invention under different cycle numbers;
[0029] Figure 6 The image shows the hot box test results of the soft-pack battery prepared with the TTE-based solid electrolyte in Example 1 of this invention. Detailed Implementation
[0030] The present invention will be further described below with reference to the accompanying drawings and embodiments. Unless otherwise defined, the technical or scientific terms used in this invention should be understood in their ordinary sense by those skilled in the art. The features mentioned above or in the specific examples mentioned in this invention can be combined arbitrarily, and these specific embodiments are only used to illustrate the invention and are not intended to limit the scope of the invention.
[0031] A method for preparing a TTE-based solid electrolyte based on in-situ polymerization includes the following steps:
[0032] S1. Disperse nanocellulose in water and ultrasonically disperse to form a uniform nanocellulose dispersion.
[0033] S2. The nanocellulose dispersion was vacuum filtered and then dried to obtain the nanocellulose support layer.
[0034] S3. Phosphazene (BGCP), trimethylolpropane triglycidyl ether (TTE), perfluoropolyether (PFPE), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium dioxalate borate (LiDFOB) are stirred and mixed to obtain TTE-based solid electrolyte slurry.
[0035] S4. The TTE-based solid electrolyte slurry obtained in S3 is coated onto the nanocellulose support layer obtained in S2, and an in-situ polymerization reaction is carried out in an oven. After the reaction is completed, a TTE-based solid electrolyte copolymerized from phosphazene, perfluoropolyether and trimethylolpropane triglycidyl ether is obtained.
[0036] By blending and in-situ polymerizing TTE, PFPE, and BGCP, followed by reinforcement with nanocellulose, an ultrathin TTE-based solid electrolyte based on in-situ polymerization of polyepoxy functional groups was successfully prepared. This electrolyte exhibits advantages such as anode interface stability, high mechanical strength, high decomposition voltage, and high ion transference number.
[0037] Preferably, in S1, the ultrasonic dispersion power is 800W and the ultrasonic dispersion time is 30-60min.
[0038] By controlling the power and time of ultrasonic dispersion within the aforementioned range, this invention can effectively break up the agglomeration of nanocellulose and form a uniform and stable dispersion, laying the foundation for the subsequent formation of a uniform and dense nanocellulose support layer, which is beneficial to improving the mechanical properties and ion transport uniformity of the solid electrolyte.
[0039] Preferably, in step S3, the mixing temperature is 60-70℃ and the mixing time is 6-8h.
[0040] By controlling the temperature and time of stirring and mixing within the above-mentioned range, this invention can ensure that all components are fully dissolved and mixed evenly, promote the complete dissociation and uniform distribution of lithium salt, and avoid component degradation or prepolymerization caused by excessively high temperature or time. This is beneficial to the formation of a uniform and stable electrolyte slurry and ensures the performance consistency of the final electrolyte membrane.
[0041] Preferably, in S3, the mass ratio of trimethylolpropane triglycidyl ether, lithium bis(trifluoromethanesulfonyl)imide, and lithium dioxalate borate is 40:10:1.
[0042] Preferably, in S3, the perfluoropolyether is 5%-15% of the total mass of trimethylolpropane triglycidyl ether, lithium bis(trifluoromethanesulfonyl)imide, and lithium dioxalate borate.
[0043] Preferably, in S3, the phosphazene is 15%-20% of the total mass of trimethylolpropane triglycidyl ether, lithium bis(trifluoromethanesulfonyl)imide, and lithium dioxalate borate.
[0044] This invention optimizes the balance between the formation of the crosslinking network and lithium-ion conduction by controlling the amount of each raw material within the above-mentioned range. TTE provides the polymer backbone, LiTFSI provides the main conductive lithium ions, LiDFOB promotes the ring-opening polymerization of the polymer, the fluorinated segments of PFPE can improve the antioxidant decomposition voltage of the electrolyte, and BGCP, as a flame retardant, can improve the flame retardant performance of the electrolyte and provide a good basis for the electrolyte's ionic conductivity and interfacial stability.
[0045] Preferably, in S4, the thickness of the nanocellulose support layer is 10-20 μm.
[0046] By controlling the thickness of the nanocellulose support layer within the aforementioned range, this invention can minimize the overall thickness and interfacial impedance of the electrolyte while ensuring sufficient mechanical support and dendrite suppression, which is beneficial for achieving ultra-thin designs of high-energy-density batteries.
[0047] Preferably, in S4, the coating thickness of the TTE-based solid electrolyte slurry is 50-100 μm.
[0048] By controlling the coating thickness of the TTE-based solid electrolyte slurry within the above-mentioned range, this invention can ensure the formation of a continuous and defect-free electrolyte functional layer, providing sufficient ion conduction paths, while avoiding excessive thickness leading to excessively long ion migration paths and increased internal resistance, or excessive thinness leading to insufficient mechanical strength and easy dendrite puncture.
[0049] Preferably, in S4, the oven temperature is 60-80℃, and the in-situ polymerization reaction time is 16-24h.
[0050] In an even more preferred embodiment, in S4, the oven temperature is 70°C and the in-situ polymerization reaction time is 20 hours.
[0051] This invention controls the temperature and time of the in-situ polymerization reaction within the above-mentioned range, which can ensure that monomers such as TTE undergo sufficient cross-linking polymerization to form a stable three-dimensional network structure. At the same time, it avoids side reactions or component decomposition caused by excessively high temperature, or incomplete polymerization caused by insufficient time, thereby ensuring that the electrolyte membrane has excellent mechanical strength, dimensional stability and electrochemical performance.
[0052] A TTE-based solid electrolyte based on in-situ polymerization, wherein the TTE-based solid electrolyte is prepared by the above-described method for preparing a TTE-based solid electrolyte based on in-situ polymerization.
[0053] Example 1
[0054] This invention provides a TTE-based solid electrolyte based on in-situ polymerization, the preparation method of which includes the following steps:
[0055] S1. Disperse nanocellulose in water and ultrasonically disperse to form a uniform nanocellulose dispersion; the ultrasonic dispersion power is 800W and the ultrasonic dispersion time is 45min.
[0056] S2. After vacuum filtration, the nanocellulose dispersion is dried at 60°C to obtain the nanocellulose support layer.
[0057] S3. 4g of trimethylolpropane triglycidyl ether (TTE), 1g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), 0.1g of lithium dioxazoborate (LiDFOB), 0.51g of perfluoropolyether (PFPE) (accounting for 10% of the total mass of TTE, LiTFSI, and LiDFOB, which is 5.1g), and 0.765g of phosphazene (BGCP) (accounting for 15% of the total mass of TTE, LiTFSI, and LiDFOB, which is 5.1g) were stirred and mixed at 70°C for 8 hours to obtain a TTE-based solid electrolyte slurry.
[0058] S4. The TTE-based solid electrolyte slurry obtained in S3 is coated onto the nanocellulose support layer obtained in S2. The thickness of the nanocellulose support layer is 15 μm, and the coating thickness of the TTE-based solid electrolyte slurry is 75 μm. Then, an in-situ polymerization reaction is carried out in an oven at 70 °C for 20 h. After the reaction is completed, a TTE-based solid electrolyte copolymerized from phosphazene, perfluoropolyether and trimethylolpropane triglycidyl ether is obtained, denoted as P-TTE-PFPE-BGCP-NC.
[0059] Example 2
[0060] This invention provides a TTE-based solid electrolyte based on in-situ polymerization, the preparation method of which includes the following steps:
[0061] S1. Disperse nanocellulose in water and ultrasonically disperse to form a uniform nanocellulose dispersion; the ultrasonic dispersion power is 800W and the ultrasonic dispersion time is 30min.
[0062] S2. After vacuum filtration, the nanocellulose dispersion is dried at 60°C to obtain the nanocellulose support layer.
[0063] S3. 4.0 g of trimethylolpropane triglycidyl ether (TTE), 1.0 g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), 0.1 g of lithium dioxalatoborate (LiDFOB), 0.255 g of perfluoropolyether (PFPE) (accounting for 5% of the total mass of TTE, LiTFSI, and LiDFOB, which is 5.1 g), and 0.765 g of phospholipid (BGCP) (accounting for 15% of the total mass of TTE, LiTFSI, and LiDFOB, which is 5.1 g) were stirred and mixed at 65 °C for 6 h to obtain a TTE-based solid electrolyte slurry.
[0064] S4. The TTE-based solid electrolyte slurry obtained in S3 is coated onto the nanocellulose support layer obtained in S2. The thickness of the nanocellulose support layer is 10 μm, and the coating thickness of the TTE-based solid electrolyte slurry is 50 μm. Then, an in-situ polymerization reaction is carried out in an oven at 60 °C for 16 h. After the reaction is completed, the TTE-based solid electrolyte is obtained.
[0065] Example 3
[0066] This invention provides a TTE-based solid electrolyte based on in-situ polymerization, the preparation method of which includes the following steps:
[0067] S1. Disperse nanocellulose in water and ultrasonically disperse to form a uniform nanocellulose dispersion; the ultrasonic dispersion power is 800W and the ultrasonic dispersion time is 60min.
[0068] S2. After vacuum filtration, the nanocellulose dispersion is dried at 60°C to obtain the nanocellulose support layer.
[0069] S3. 4.0 g of trimethylolpropane triglycidyl ether (TTE), 1.0 g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), 0.1 g of lithium dioxalatoborate (LiDFOB), 0.765 g of perfluoropolyether (PFPE) (accounting for 15% of the total mass of TTE, LiTFSI, and LiDFOB, which is 5.1 g), and 1.02 g of phospholipid (BGCP) (accounting for 20% of the total mass of TTE, LiTFSI, and LiDFOB, which is 5.1 g) were stirred and mixed at 70 °C for 8 h to obtain a TTE-based solid electrolyte slurry.
[0070] S4. The TTE-based solid electrolyte slurry obtained in S3 is coated onto the nanocellulose support layer obtained in S2. The thickness of the nanocellulose support layer is 20 μm, and the coating thickness of the TTE-based solid electrolyte slurry is 100 μm. Then, an in-situ polymerization reaction is carried out in an oven at 80 °C for 24 h. After the reaction is completed, the TTE-based solid electrolyte is obtained.
[0071] Comparative Example 1
[0072] The difference from Example 1 is that no phosphazene was added in S3, but everything else was the same as in Example 1. The resulting TTE-based solid electrolyte was denoted as P-TTE-PFPE-NC.
[0073] Comparative Example 2
[0074] The difference from Example 1 is that no perfluoropolyether and phosphazene were added in S3, while the rest were the same as in Example 1. The resulting TTE-based solid electrolyte was denoted as P-TTE-NC.
[0075] The TTE-based solid electrolytes prepared in Examples 1-3 and Comparative Examples 1-2 were characterized in terms of morphology and performance, and the results are as follows:
[0076] The TTE-based solid electrolytes prepared in Examples 1, 2, and 3 of this invention were subjected to stress-strain tests using a tensile testing method. The results are as follows: Figure 1 As shown.
[0077] Depend on Figure 1 It can be seen that the tensile strength of the TTE-based solid electrolyte prepared in Example 1 is 7.91 MPa and the fracture energy is 0.33 J / m. -3 The tensile strength of Example 3 was 7.69 MPa and the fracture energy was 0.24 J / m. -3 The tensile strength of Example 3 is similar to that of Example 1. This is because the polymerization rate of Example 3 is too high, resulting in a lower elongation than Example 1 while maintaining similar tensile strength. Example 2 has a tensile strength of 4.22 MPa and a fracture energy of 0.14 J / m². -3 Its mechanical properties are far superior to those of Comparative Example 1, which has a strength of 3.60 MPa and a strength of 0.09 Jm. -3 This is because the addition of perfluoropolyether can increase the degree of polymerization of TTE-based solid electrolytes. Comparative Example 2 has a tensile strength of 3.37 MPa and a fracture energy of 0.03 J / m². -3 This is because the electrolyte is difficult to polymerize when only TTE is present, and cellulose has poor mechanical strength and lacks a plastic deformation stage. In summary, the appropriate degree of polymer polymerization and the moderate thickness of the nanocellulose support layer in Example 1 create a synergistic reinforcing effect, effectively improving the mechanical strength of the electrolyte and better blocking the penetration of lithium dendrites.
[0078] The TTE-based solid electrolytes prepared in Examples 1, 2, 3, Comparative Example 1, and Comparative Example 2 of this invention were subjected to ionic conductivity testing using electrochemical impedance spectroscopy (EIS). The results are as follows: Figure 2 As shown.
[0079] Depend on Figure 2 It can be seen that the ionic conductivity of the TTE-based solid electrolyte prepared in Example 1 is 5.3 × 10⁻⁶. -4 S cm -1 The TTE-based solid electrolyte prepared in Example 2 has an ionic conductivity of 2.6 × 10⁻⁶. -4 S cm -1 The TTE-based solid electrolyte prepared in Example 3 has an ionic conductivity of 4.0 × 10⁻⁶. -4 S cm -1 The ionic conductivity of the TTE-based solid electrolyte prepared in Comparative Example 1 was 1.8 × 10⁻⁶. -4 S cm -1The TTE-based solid electrolyte prepared in Comparative Example 2 has an ionic conductivity of 9.4 × 10⁻⁶. -5 S cm -1 The ionic conductivity of the TTE-based solid electrolyte prepared in Example 1 is much higher than that of Examples 2, 3, Comparative Example 1, and Comparative Example 2. This is because the cross-linked network formed by the in-situ polymerization of TTE disrupts the orderliness of the chain segments and reduces the crystallinity of the polymer. At the same time, the introduction of PFPE optimizes the ion transport channels, and the nanocellulose support layer further increases the ion transference number. The synergistic effect of these three factors significantly improves the ionic conductivity of the electrolyte.
[0080] The TTE-based solid electrolytes prepared in Example 1, Comparative Example 1, and Comparative Example 2 of this invention were tested using a linear voltammetric method, and the results are as follows: Figure 3 As shown.
[0081] Depend on Figure 3 It can be seen that the decomposition voltage of the TTE-based solid electrolyte prepared in Example 1 is 5.05V, the decomposition voltage of the TTE-based solid electrolyte prepared in Comparative Example 1 is 4.21V, and the decomposition voltage of the TTE-based solid electrolyte prepared in Comparative Example 2 is 4.93V. The decomposition voltage of the TTE-based solid electrolyte prepared in Example 1 is higher than that of Comparative Example 1 and Comparative Example 2. This is because the large number of CF groups contained in PFPE has extremely high oxidation resistance, and can build a stable CEI layer on the cathode surface during cycling, effectively inhibiting the oxidative decomposition of the electrolyte, thereby increasing the decomposition voltage and enabling it to match the higher operating voltage of the NCM811 cathode.
[0082] The critical current density of the TTE-based solid electrolytes prepared in Examples 1, 1, and 2 of this invention was tested using the galvanostatic polarization method, and the results are as follows: Figure 4 As shown.
[0083] Depend on Figure 4 It can be seen that the symmetric battery assembled with the TTE-based solid electrolyte prepared in Example 1 can cycle stably under a small polarization. The symmetric battery assembled in Example 1 can cycle stably for more than 1000 hours, and the polarization voltage remains at a low level. However, the symmetric batteries assembled in Comparative Examples 1 and 2 have poor cycle stability, and the polarization voltage gradually increases. After 500 hours of cycling, a significant voltage change occurs, indicating that the electrolyte membrane is pierced by lithium dendrites.
[0084] The TTE-based solid electrolytes prepared in Examples 1, 1, and 2 of this invention were assembled into coin cells with NCM811 positive electrodes and lithium metal negative electrodes, respectively. Electrochemical performance tests were performed on the two types of coin cells, and the results are as follows: Figure 5 As shown.
[0085] Depend on Figure 5It can be seen that the button battery assembled in Example 1 retained 87.4% of its capacity after 200 cycles, and had relatively small charge-discharge curve polarization; the button battery assembled in Comparative Example 1 retained 77.4% of its capacity after 200 cycles, and had relatively large charge-discharge curve polarization. The battery in Comparative Example 2 experienced a short circuit after 69 cycles. The electrolyte in Example 1 has better cycle stability and less polarization.
[0086] The TTE-based solid electrolyte prepared in Example 1 of this invention, along with an NCM811 cathode and lithium foil, was assembled into a pouch cell and subjected to a hot box test. The results are as follows: Figure 6 As shown.
[0087] Depend on Figure 6 It can be seen that the voltage of the pouch cell did not change significantly during the heating process, indicating that the prepared solid electrolyte does not decompose or flammable at high temperatures and has good safety performance.
[0088] Therefore, the present invention employs the aforementioned in-situ polymerization-based TTE-based solid electrolyte and its preparation method. The prepared TTE-based solid electrolyte, based on the in-situ polymerization of polyepoxy functional groups, exhibits superior overall performance in terms of mechanical properties, ionic conductivity, and symmetric battery constant current cycling performance. The assembled battery demonstrates better cycle performance and can pass hot-box testing. The electrolyte membrane prepared by this invention is beneficial for achieving high energy density in all-solid-state lithium metal batteries.
[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.
Claims
1. A method for preparing a TTE-based solid electrolyte based on in-situ polymerization, characterized in that: Includes the following steps: S1. Disperse nanocellulose in water and ultrasonically disperse to form a uniform nanocellulose dispersion. S2. The nanocellulose dispersion was vacuum filtered and then dried to obtain the nanocellulose support layer. S3. Phosphazene, trimethylolpropane triglycidyl ether, perfluoropolyether, lithium bis(trifluoromethanesulfonylimide) and lithium dioxalate borate are stirred and mixed to obtain TTE-based solid electrolyte slurry. S4. The TTE-based solid electrolyte slurry obtained in S3 is coated onto the nanocellulose support layer obtained in S2, and an in-situ polymerization reaction is carried out in an oven. After the reaction is completed, a TTE-based solid electrolyte copolymerized from phosphazene, perfluoropolyether and trimethylolpropane triglycidyl ether is obtained.
2. The method for preparing a TTE-based solid electrolyte based on in-situ polymerization according to claim 1, characterized in that: In S1, the ultrasonic dispersion power is 800W, and the ultrasonic dispersion time is 30-60min.
3. The method for preparing a TTE-based solid electrolyte based on in-situ polymerization according to claim 1, characterized in that: In S3, the mixing temperature is 60-70℃, and the mixing time is 6-8h.
4. The method for preparing a TTE-based solid electrolyte based on in-situ polymerization according to claim 1, characterized in that: In S3, the mass ratio of trimethylolpropane triglycidyl ether, lithium bis(trifluoromethanesulfonyl)imide, and lithium dioxalatoborate is 40:10:
1.
5. The method for preparing a TTE-based solid electrolyte based on in-situ polymerization according to claim 1, characterized in that: In S3, the perfluoropolyether is 5%-15% of the total mass of trimethylolpropane triglycidyl ether, lithium bis(trifluoromethanesulfonyl)imide, and lithium dioxalate borate.
6. The method for preparing a TTE-based solid electrolyte based on in-situ polymerization according to claim 1, characterized in that: In S3, the phosphazene is 15%-20% of the total mass of trimethylolpropane triglycidyl ether, lithium bis(trifluoromethanesulfonyl)imide, and lithium dioxalatoborate.
7. The method for preparing a TTE-based solid electrolyte based on in-situ polymerization according to claim 1, characterized in that: In S4, the thickness of the nanocellulose support layer is 10-20 μm.
8. The method for preparing a TTE-based solid electrolyte based on in-situ polymerization according to claim 1, characterized in that: In S4, the coating thickness of the TTE-based solid electrolyte slurry is 50-100 μm.
9. The method for preparing a TTE-based solid electrolyte based on in-situ polymerization according to claim 1, characterized in that: In S4, the oven temperature is 60-80℃, and the in-situ polymerization reaction time is 16-24h.
10. A TTE-based solid electrolyte based on in-situ polymerization, characterized in that, The TTE-based solid electrolyte is prepared using the method for preparing TTE-based solid electrolyte based on in-situ polymerization as described in any one of claims 1-9.