Polyether-based solid electrolyte membrane and preparation method thereof

Abstract

The invention relates to the technical field of lithium battery electrolytes, in particular to a preparation method of a polyether-based solid electrolyte and application of the polyether-based solid electrolyte in electrochemical devices such as lithium metal batteries. The polyether-based solid electrolyte material comprises a porous polymer skeleton, a cyclic ether monomer, a copper-based compound, a lithium salt and a plasticizing additive. The preparation method comprises the following steps: loading a copper-based compound into a porous polymer skeleton, adding cyclic ether, lithium salt and the like to carry out in-situ ring opening polymerization, cooperatively constructing a polyether-porous polymer skeleton three-dimensional network structure, and improving the mechanical strength of the electrolyte. Wherein the copper-based compound widens the chain spacing of the porous polymer, and is convenient for the cyclic ether monomer to penetrate into the skeleton; meanwhile, the in-situ ring-opening polymerization of the cyclic ether promotes the close contact between the electrolyte and an electrode, the interface impedance is reduced, and the ionic conductivity is improved. The polyether-based solid electrolyte prepared by the invention can promote stable circulation of a lithium metal battery.

Description

Technical Field

[0001] This invention relates to the technical field of lithium battery electrolytes, specifically to a method for preparing a polyether-based solid electrolyte and its application in electrochemical devices such as lithium metal batteries. Background Technology

[0002] With the urgent global need to reduce fossil fuel consumption and advance carbon neutrality, the new energy industry, primarily based on solar, wind, tidal, and geothermal energy, is booming. However, new energy power generation is intermittent and unstable, making energy storage technology crucial for addressing energy mismatches in time and space and achieving stable energy supply. As the core of energy storage systems, the performance of batteries directly determines the application scenarios and development potential of new energy sources.

[0003] The rapidly developing market is placing increasingly higher demands on battery energy density. Traditional lithium-ion batteries are gradually approaching their theoretical energy density limit, while lithium metal batteries, with their ultra-high theoretical specific capacity and lowest redox potential, have become an ideal choice for breaking through the energy density bottleneck. However, lithium metal batteries using traditional liquid electrolytes suffer from safety hazards such as lithium dendrite growth piercing the separator and causing short circuits, and the flammability and leakage of the electrolyte leading to thermal runaway, which greatly limits their commercial application. In contrast, solid-state electrolytes use solid materials instead of flammable liquids, fundamentally eliminating the risks of leakage and combustion, while also inhibiting lithium dendrite growth and improving battery safety.

[0004] Polymer solid electrolytes (SSEs) have become a research hotspot in recent years due to their unique molecular structure and performance characteristics. They possess excellent flexibility, ease of processing, and better interfacial compatibility than inorganic SSEs. Among SSEs, polycyclic ether polymers, through the Lewis base effect of their ether-oxygen bond-rich (-COC-) backbone, can coordinate with lithium ions, thereby promoting ion transport within lithium batteries. Simultaneously, due to the low viscosity of their monomers, ether polymers exhibit good wettability to separator and electrode materials. After in-situ polymerization within the battery, they can achieve close contact with the electrode active materials, thereby reducing interfacial resistance, and thus have been extensively studied.

[0005] However, as polymers, polyether electrolytes have low intrinsic mechanical strength and are not easily resistant to the growth of lithium dendrites. Furthermore, ethers have a narrow electrochemical window due to their easy oxidation and decomposition, making them susceptible to high voltage during battery cycling. At the same time, polyether electrolytes suffer from the common problems of polymer electrolytes: low ionic conductivity and slow ion migration. Therefore, improving ionic conductivity and promoting rapid lithium-ion transport is an important research direction for improving the performance of polyether solid electrolyte batteries. Summary of the Invention

[0006] Therefore, the technical problem to be solved by the present invention is to overcome the problems of low mechanical strength, narrow electrochemical window and low ionic conductivity of polyether electrolytes, thereby providing a new method for preparing cyclic polyether-based solid electrolytes and their applications.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing a polyether-based solid electrolyte includes the following steps:

[0009] S1. A porous polymer framework is provided;

[0010] S2. Load copper-based compounds onto the porous polymer framework described in S1 to achieve the effect of widening the spacing between porous polymer chains.

[0011] S3. Contact the porous polymer framework loaded with copper-based compounds described in S2 with the composition containing cyclic ether monomers.

[0012] S4. Utilizing the initiating effect of the copper-based compound, the cyclic ether monomer is initiated to undergo ring-opening polymerization inside or on the surface of the porous polymer framework to form a gel-state solid electrolyte.

[0013] Furthermore, the cyclic ether monomer is one or more of 1,3-dioxolane, ethylene oxide, butoxycyclohexane, and tetrahydrofuran.

[0014] Furthermore, the copper-based compound initiator is selected from one or more of the following: copper ions, copper salts, copper oxides, copper hydroxides, copper complexes, copper chelates, etc., which have ions that can access the Lewis acidic center.

[0015] Furthermore, the ligands of the copper-based compound are selected from one or more of the following: hydroxyl groups, water, ammonia, amine compounds, ethylenediamine, ethylenediaminetetraacetic acid, acetylacetone, and amino acids.

[0016] Furthermore, the porous polymer framework is a natural polymer material framework or a synthetic polymer framework;

[0017] The framework of the natural polymer material is one of cellulose or its derivatives, chitosan or its derivatives, etc.

[0018] The synthetic polymer material skeleton is one of polyvinylidene fluoride-co-hexafluoropropylene, polyacrylonitrile, polyimide, etc.

[0019] Furthermore, the composition containing cyclic ether monomers described in step S3 also contains lithium salts or plasticizers.

[0020] The lithium salt includes one or more of LiPF6, LiBF4, LiTFSI, LiODFB, etc.

[0021] The plasticizer may be one or more of FEC, FEMC, PFPN, etc.

[0022] The present invention also provides an electrochemical device comprising a positive electrode, a negative electrode and an electrolyte disposed therebetween, wherein the electrolyte is a solid electrolyte obtained by the above preparation method.

[0023] The technical solution of this invention has the following advantages:

[0024] 1. The present invention provides a method for preparing a polyether-based solid electrolyte, which achieves a dual effect by using a copper-based compound. On the one hand, the copper-based compound enters the porous polymer chain and widens the inter-chain spacing through coordination. On the other hand, the copper-based compound acts as an initiator to initiate the ring-opening polymerization of cyclic ethers. The dual effects work together to promote the construction of a solid electrolyte with a fast lithium-ion transport channel.

[0025] 2. The present invention provides a method for preparing a polyether-based solid electrolyte, which uses a porous polymer framework as a support. On the one hand, it provides attachment sites for copper-based compounds, allowing cyclic ether monomers that enter the framework to contact the initiator and complete ring-opening polymerization. On the other hand, the porous polymer framework can enhance the mechanical strength of the polymer solid electrolyte.

[0026] 3. The method for preparing a polyether-based solid electrolyte provided by the present invention has mild initiation conditions and stable residues, which can effectively improve the stability of the polyether-based electrolyte in battery cycling and broaden the electrochemical window of the polyether-based electrolyte.

[0027] 4. The present invention provides a method for preparing a polyether-based solid electrolyte, wherein the chain structure of the polymer provides a large number of channels for lithium-ion transport, which can effectively improve the ionic conductivity. Attached Figure Description

[0028] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 The XRD pattern of the BC film obtained in Example 1 of this invention shows that the left shift of the characteristic peaks proves the expansion of the BC lattice spacing.

[0030] Figure 2 The infrared spectrum of the BC film obtained in Example 1 of this invention shows that the appearance of the characteristic peak of the long chain of PDOL proves the successful polymerization of DOL.

[0031] Figure 3 The LSV test results of the solid electrolyte prepared in Example 1 of this invention show a wide electrochemical window.

[0032] Figure 4 The images show the AC impedance spectrum and scanning electron microscope (SEM) cross-section of the solid electrolyte prepared in Example 1 of this invention. The ionic conductivity can be calculated to be 2.98 × 10⁻⁶. -4 S cm -1 ;

[0033] Figure 5 The charge-discharge curves of the symmetrical battery assembled with the solid electrolyte prepared in Example 1 of this invention show that it can achieve stable cycling for at least 500 hours.

[0034] Figure 6 The image shows the CCD test curve of the symmetric battery assembled with the solid electrolyte prepared in Example 1 of this invention, with a maximum current reaching 2.4 mA cm⁻¹. -2 ;

[0035] Figure 7 This is the charge-discharge cycle curve of the LFP||Li full cell assembled with solid electrolyte prepared in Example 1 of the present invention at 1C, which can be stably cycled for at least 250 cycles;

[0036] Figure 8 This is the rate cycling curve of the LFP||Li full cell assembled with the solid electrolyte prepared in Example 1 of this invention at 1C, which can achieve stable and reversible cycling at 1C-10C. Detailed Implementation

[0037] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0038] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0039] Example 1

[0040] This embodiment provides a lithium metal battery assembled with a polyether-based solid electrolyte material. The solid electrolyte framework is bacterial cellulose (BC) treated with [Cu(OH)4]2-. The raw material for preparing the polyether-based electrolyte is DOL monomer, the raw material for preparing the lithium salt is LiTFSI, and the raw material for preparing the plasticizer is FEC. The specific preparation method is as follows:

[0041] S1. Place BC under a hot press and press at 2MPa pressure at room temperature for 24 hours to remove the moisture inside BC;

[0042] S2. Prepare a copper sheet containing Cu by soaking it in a 20wt% NaOH solution beforehand. 2+ The pressed BC was then immersed in an alkaline solution at room temperature for 4 days to allow Cu to... 2+ Fully penetrate the BC chain segment;

[0043] S3. Rinse the soaked BC with deionized water until neutral, then soak it in DMF for 24 hours to remove the residual moisture inside.

[0044] S4. Take out BC, dry it to remove DMF, cut BC into round pieces with a diameter of 16mm, put them into a glove box filled with Ar atmosphere, soak them in a solution containing DOL:FEC=1:1 and 1M LiTFSI for 48h, so that DOL monomer can fully enter the interior of BC and polymerize into PDOL segments inside to form Cu-PDOL-BC structure, and place them in the glove box for later use.

[0045] S5. Using BC wafers as solid electrolytes, LFP and lithium foil negative electrodes are matched to form an LFP|Cu-PDOL-BC|Li battery structure. The battery is left to stand for 48 hours to ensure that DOL between the electrolyte surface and the positive and negative electrodes is polymerized in situ into PDOL, reducing the interfacial contact resistance.

[0046] The solid electrolyte material obtained in this embodiment is based on BC as the backbone. After using [Cu(OH)4]2- to expand the BC chain spacing, DOL monomers containing lithium salt and FEC molecules enter the BC chain spacing. After in-situ polymerization, good lithium ion transport channels are formed inside BC.

[0047] Example 2

[0048] This embodiment provides a lithium metal battery assembled with a polyether-based solid electrolyte material. The solid electrolyte framework is made of cellulose nanofibers (CNF) treated with [Cu(OH)4]2-. The raw material for preparing the polyether-based electrolyte is DOL monomer, the raw material for preparing the lithium salt is LiTFSI, and the raw material for preparing the plasticizer is FEC. The specific preparation method is as follows:

[0049] S1. Use a vacuum filter to remove water from the CNF suspension to obtain CNF flakes;

[0050] S2. Prepare a copper sheet containing Cu by soaking it in a 20wt% NaOH solution beforehand. 2+ The CNF sheet was then immersed in an alkaline solution at room temperature for 4 days to allow the Cu... 2+ Fully penetrate the CNF chain segment;

[0051] S3. Rinse the soaked cellulose with deionized water until neutral, then soak it in DMF for 24 hours to remove any residual moisture.

[0052] S4. Take out CNF, dry it to remove DMF, cut CNF into 16mm diameter round pieces, put them into a glove box filled with Ar atmosphere, and soak them in a solution containing DOL:FEC=1:1 and 1M LiTFSI for 48h to allow DOL monomer to fully enter the CNF and polymerize into PDOL segments inside to form Cu-PDOL-CNF structure. Place them in the glove box for later use.

[0053] S5. Using CNF sheets as solid electrolytes, LFP and lithium sheet anodes are matched to form an LFP|Cu-PDOL-CNF|Li battery structure. The battery is left to stand for 48 hours to ensure that DOL between the electrolyte surface and the positive and negative electrodes is polymerized in situ into PDOL, reducing interfacial contact resistance.

[0054] The solid electrolyte material obtained in this embodiment is based on CNF as a backbone. After using [Cu(OH)4]2- to expand the CNF interchain spacing, DOL monomers containing lithium salts and FEC molecules enter the CNF interchain. After in-situ polymerization, a good lithium-ion transport channel is formed inside the CNF.

[0055] Example 3

[0056] This embodiment provides a lithium metal battery assembled with a polyether-based solid electrolyte material. The solid electrolyte framework is bacterial cellulose (BC) treated with [Cu(NH3)4]2+. The raw material for preparing the polyether-based electrolyte is DOL monomer, the raw material for preparing the lithium salt is LiTFSI, and the raw material for preparing the plasticizer is FEC. The specific preparation method is as follows:

[0057] S1 and BC pretreatment are the same as in Example 1;

[0058] S2. Prepare a copper ammonia solution, then soak the pressed BC in the copper ammonia solution at room temperature for 4 days to allow Cu to... 2+ Fully penetrate the BC chain segment;

[0059] S3. Rinse the soaked BC with deionized water until neutral, then soak it in DMF for 24 hours to remove the residual moisture inside.

[0060] S4. Take out BC, dry it to remove DMF, cut BC into round pieces with a diameter of 16mm, put them into a glove box filled with Ar atmosphere, soak them in a solution containing DOL:FEC=1:1 and 1M LiTFSI for 48h, so that DOL monomer can fully enter the interior of BC and polymerize into PDOL segments inside to form Cu-PDOL-BC structure, and place them in the glove box for later use.

[0061] S5. Using BC wafers as solid electrolytes, LFP and lithium foil negative electrodes are matched to form an LFP|Cu-PDOL-BC|Li battery structure. The battery is left to stand for 48 hours to ensure that DOL between the electrolyte surface and the positive and negative electrodes is polymerized in situ into PDOL, reducing the interfacial contact resistance.

[0062] The solid electrolyte material obtained in this embodiment is based on BC as the backbone. After the [Cu(NH3)4]2+ in the copper ammonia solution is used to expand the interchain spacing of BC, DOL monomers containing lithium salt and FEC molecules enter the interchain spacing of BC. After in-situ polymerization, good lithium ion transport channels are formed inside BC.

[0063] Example 4

[0064] This embodiment provides a lithium metal battery assembled with a polyether-based solid electrolyte material. The solid electrolyte framework is made of cellulose nanofibers (CNF) treated with [Cu(NH3)4]2+. The polyether-based electrolyte is prepared from DOL monomer, the lithium salt from LiTFSI, and the plasticizer from FEC. The specific preparation method is as follows:

[0065] S1, CNF preprocessing is the same as in Example 2;

[0066] S2. Prepare a copper ammonia solution, then soak the pressed BC in the copper ammonia solution at room temperature for 4 days to allow Cu to... 2+ Fully penetrate the CNF chain segment;

[0067] S3. Rinse the soaked cellulose with deionized water until neutral, then soak it in DMF for 24 hours to remove any residual moisture.

[0068] S4. Take out CNF, dry it to remove DMF, cut CNF into 16mm diameter round pieces, put them into a glove box filled with Ar atmosphere, and soak them in a solution containing DOL:FEC=1:1 and 1M LiTFSI for 48h to allow DOL monomer to fully enter the CNF and polymerize into PDOL segments inside to form Cu-PDOL-CNF structure. Place them in the glove box for later use.

[0069] S5. Using CNF sheets as solid electrolytes, LFP and lithium sheet anodes are matched to form an LFP|Cu-PDOL-CNF|Li battery structure. The battery is left to stand for 48 hours to ensure that DOL between the electrolyte surface and the positive and negative electrodes is polymerized in situ into PDOL, reducing interfacial contact resistance.

[0070] The solid electrolyte material obtained in this embodiment is based on CNF as a backbone. After using [Cu(NH3)4]2+ to expand the CNF interchain spacing, DOL monomers containing lithium salts and FEC molecules enter the CNF interchain. After in-situ polymerization, a good lithium-ion transport channel is formed inside the CNF.

[0071] Example 5

[0072] This embodiment provides a lithium metal battery assembled with a polyether-based solid electrolyte material. The solid electrolyte framework is a poly(vinylidene fluoride-co-hexafluoropropylene) porous membrane treated with copper acetylacetonate (Cu(acac)2). The polyether-based electrolyte is prepared from propylene oxide (PO) monomer, the lithium salt from LiTFSI, and the plasticizer from FEC. The specific preparation method is as follows:

[0073] S1. Cut the commercial PVDF-HFP porous membrane into circular pieces with a diameter of 16mm;

[0074] S2. Prepare Cu(acac)2 ethanol solution. Immerse the PVDF-HFP disc in Cu(acac)2 ethanol solution at room temperature for 12 hours to load Cu(acac)2 into the membrane pores. After removal, gently rinse the surface with anhydrous ethanol to remove residual liquid and dry for later use.

[0075] S3. Place the PVDF-HFP disc loaded with Cu(acac)2 into a glove box filled with Ar atmosphere and soak it in a solution containing DOL:FEC=1:1 and 1M LiTFSI for 48h to allow the PO monomer to fully enter the interior of the PVDF-HFP and polymerize into PPO segments inside, forming a Cu-PPO-PVDF-HFP structure. Place it in the glove box for later use.

[0076] S4. Using PVDF-HFP sheets as solid electrolytes, LFP and lithium sheet negative electrodes are matched to form an LFP|Cu-PPO-PVDF-HFP|Li battery structure. The battery is left to stand for 48 hours to ensure that PO between the electrolyte surface and the positive and negative electrodes is polymerized in situ into PPO, thereby reducing interfacial contact resistance.

[0077] The solid electrolyte material obtained in this embodiment is based on the synthetic polymer PVDF-HFP as the backbone. After using Cu(acac)2 to expand the interchain spacing of PVDF-HFP, PO monomers containing lithium salt and FEC molecules enter the interchain spacing of PVDF-HFP. After in-situ polymerization, a good lithium-ion transport channel is formed inside PVDF-HFP.

[0078] Example 6

[0079] This embodiment provides a lithium metal battery assembled with a polyether-based solid electrolyte material. The solid electrolyte framework is bacterial cellulose (BC) treated with a simple copper salt (CuCl2). The raw material for the polyether-based electrolyte is 1,3-dioxane (DOX) monomer. The raw material for preparing the lithium salt is LiTFSI, and the raw material for preparing the plasticizer is FEC. The specific preparation method is as follows:

[0080] S1 and BC pretreatment are the same as in Example 1;

[0081] S2. Immerse the pretreated BC membrane in a saturated CuCl2 solution for four days to allow the Cu... 2+ The successful payload is located within the BC chain segment;

[0082] S3, subsequent water washing, DMF replacement and drying steps are the same as in Example 1;

[0083] S4. Cut the treated BC into round pieces with a diameter of 16mm, put them into a glove box filled with Ar atmosphere, and soak them in a solution containing DOX:FEC = 1:1 and 1M LiTFSI.

[0084] S5. After sealing, place it in a 60℃ oven and let it stand for 96 hours to allow the DOX monomer to fully enter the interior of BC and polymerize into PDOX segments inside, forming a Cu-PDOX-BC structure. Place it in a glove box for later use.

[0085] S6. Using the treated BC sheet as a solid electrolyte, and matching it with LFP and lithium sheet negative electrodes, an LFP|Cu-PDOX-BC|Li battery structure is formed. The battery is left to stand for 48 hours to ensure that DOX between the electrolyte surface and the positive and negative electrodes is polymerized in situ into PDOX, thereby reducing the interfacial contact resistance.

[0086] This embodiment demonstrates that the present invention is also effective for the polymerization of six-membered cyclic ether DOX with low polymerization activity, requiring only an appropriate increase in reaction temperature and an extension of reaction time. It also verifies that inorganic copper salt CuCl2 can also serve as an effective initiator.

[0087] Example 7

[0088] This embodiment provides a lithium metal battery assembled with a polyether-based solid electrolyte material. The solid electrolyte framework is chitosan treated with a simple copper salt, CuSO4. The raw material for the polyether-based electrolyte is DOL monomer, the raw material for the lithium salt is LiTFSI, and the raw material for the plasticizer is FEC. The specific preparation method is as follows:

[0089] S1. Chitosan is dissolved in dilute acetic acid solution, cast into a film, and then soaked in sodium hydroxide solution, washed and dried to prepare a porous chitosan membrane.

[0090] S2. Immerse the chitosan membrane in a 0.5M CuSO4 aqueous solution for 48 hours, utilizing the amino groups on the chitosan and Cu... 2+ Strong coordination of Cu 2+ Successful load;

[0091] S3, subsequent water washing, DMF replacement and drying steps are the same as in Example 1;

[0092] S4. Cut the treated chitosan membrane into round pieces with a diameter of 16mm, place them in a glove box filled with Ar atmosphere, and soak them in a solution containing DOL:FEC=1:1 and 1M LiTFSI for 48h to allow the DOL monomer to fully enter the interior of the chitosan membrane and polymerize into PDOL segments inside. Place them in the glove box for later use.

[0093] S5. Using chitosan sheets as a solid electrolyte, a full cell structure is formed by matching LFP and lithium sheet negative electrodes. The battery is left to stand for 48 hours to ensure that DOL between the electrolyte surface and the positive and negative electrodes is polymerized in situ into PDOL, thereby reducing interfacial contact resistance.

[0094] This embodiment demonstrates that the present invention is applicable to chitosan, a natural polymer backbone containing amino groups, and Cu. 2+ The coordination with amino groups helps stabilize the load, further enriching the selection of porous frameworks.

[0095] Comparative Example 1

[0096] This comparative example provides a lithium metal battery assembled with a polyether-based solid electrolyte material. The solid electrolyte framework is a bacterial cellulose membrane (BC) treated with a simple iron salt (FeCl3). The raw material for the polyether-based electrolyte is DOL monomer, the raw material for the lithium salt is LiTFSI, and the raw material for the plasticizer is FEC. The specific preparation method is as follows:

[0097] The BC membrane was treated with 1M FeCl3 instead of the copper alkali solution containing [Cu(OH)4]2- in step S2, and the remaining steps were the same as in Example 1.

[0098] The resulting BC film turned brownish-red. Although some polymerization may have eventually occurred, the resulting electrolyte had a narrow electrochemical window, leading to poor cycle performance and rapid capacity decay in the assembled battery. This demonstrates the presence of Fe. 3+ Not suitable for this system.

[0099] Comparative Example 2

[0100] This comparative example uses copper-based MOF (Cu-ZIF-67) to treat bacterial cellulose membranes (BC). The polyether-based electrolyte is prepared from DOL monomer, the lithium salt from LiTFSI, and the plasticizer from FEC. The specific preparation method is as follows:

[0101] In step S2, the BC membrane is immersed in an ethanol dispersion of Cu-ZIF-67 nanoparticles, and the MOF particles are attached to the surface and pores of the BC membrane by vacuum filtration. The remaining steps are the same as in Example 1.

[0102] The obtained BC membrane was immersed in DOL electrolyte. Infrared spectroscopy revealed that the characteristic peaks of DOL did not show obvious flattening, indicating that the polymerization reaction did not occur or the conversion rate was extremely low. This proved that the copper centers locked inside the MOF lattice could not contact the DOL monomers and initiate polymerization.

[0103] Experimental Example 1

[0104] XRD testing: The BC films obtained from different steps in Example 1 were placed in an XRD testing instrument for XRD testing. The structural peaks are as follows: Figure 1 As shown.

[0105] Reference Figure 1 It can be seen that after treatment with copper-based compounds and in-situ polymerization with DOL, the structural peak of cellulose BC shifted to the left, indicating that its lattice spacing was effectively expanded, proving the structural regulation effect of the treatment method of the present invention on porous framework polymers.

[0106] Experimental Example 2

[0107] Infrared testing: The BC films obtained from different steps in Example 1 were placed in an infrared spectrometer for infrared testing. The test structure is as follows. Figure 2 As shown.

[0108] Reference Figure 2 It can be seen that after treatment with DOL, the characteristic peak of the long chain of PDOL appeared in the BC membrane, proving the initiation effect of the copper-based compound on the DOL monomer, and the DOL was successfully polymerized.

[0109] Experimental Example 3

[0110] Electrochemical window testing: Using the solid electrolyte obtained in Example 1, a Li||SS battery was assembled according to conventional methods, and LSV testing was performed to test its electrochemical window. The test results are as follows: Figure 3 As shown.

[0111] Reference Figure 3 It can be seen that at 0.1mV s -1 At the specified scan rate, the scan range was 3.0-6.0V, and the current did not increase significantly, indicating that the solid electrolyte has good oxidation stability and can exist stably under high charge and discharge voltages.

[0112] Test Example 4

[0113] Conductivity Testing: A solid electrolyte was obtained using the treatment described in Example 1. An SS||SS battery was assembled according to standard methods, and AC impedance testing was performed using an electrochemical workstation. The cross-section of the solid electrolyte was observed using a scanning electron microscope, and the thickness of the solid electrolyte was measured. The ionic conductivity of the solid electrolyte could then be calculated. The results are as follows: Figure 4 As shown.

[0114] Reference Figure 4 It can be seen that the ionic conductivity of this solid electrolyte is 2.98 × 10⁻⁶. -4 S cm -1 This indicates that it can effectively promote lithium-ion transport during battery cycling.

[0115] Experimental Example 5

[0116] Cyclic stability testing: The solid electrolyte obtained in Example 1 was used to assemble a symmetrical battery using conventional methods. Charge-discharge cycling and CCD testing were performed using the Newway system. The test results are as follows: Figure 5 and Figure 6 As shown.

[0117] Reference Figure 5 It can be seen that at 30℃, 1mA cm -2 Under normal charge and discharge conditions, the symmetrical battery assembled with the BC solid electrolyte obtained by Example 1 can cycle stably for more than 500 hours, and the polarization is small and constant.

[0118] Reference Figure 6 It can be seen that, in a 30°C environment, by increasing the current in a stepwise manner, the symmetrical battery assembled using the BC solid electrolyte obtained in Example 1 can achieve a current of 2.4 mA cm⁻¹. -2 Stable cycle.

[0119] The solid electrolyte obtained using Example 1 was assembled into an LFP||Li full cell using conventional methods. Charge-discharge cycle testing and rate testing were performed using a Newway system. The test results are as follows: Figure 7 and Figure 8 As shown.

[0120] Reference Figure 7 It can be seen that, under the conditions of 30°C and 1C charge-discharge, the LFP full cell assembled with the solid electrolyte obtained by Example 1 can stably cycle for more than 250 cycles, and the coulombic efficiency is above 80%.

[0121] Reference Figure 8 It can be seen that, when the LFP full cell assembled with the solid electrolyte obtained by Example 1 is subjected to a rate cycle test of 1C-10C at 30℃, it can achieve stable and reversible cycling at 1C-10C.

[0122] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method of preparing a solid-state electrolyte, characterized by, The method comprises the following steps: S1, providing a porous polymer skeleton; S2, loading the porous polymer skeleton of S1 with a copper-based compound; S3, contacting the porous polymer skeleton loaded with the copper-based compound of S2 with a composition containing a cyclic ether monomer; S4, using the initiation of the copper-based compound to initiate ring-opening polymerization of the cyclic ether monomer inside or on the surface of the porous polymer skeleton to form a gel-state solid-state electrolyte.

2. The method of claim 1, wherein, The cyclic ether monomer is one or more of 1,3-dioxolane, oxirane, butyloxirane, and tetrahydrofuran.

3. The method of claim 1, wherein, The copper-based compound initiator is selected from one or more of copper ions, copper salts, copper oxides, copper hydroxides, copper complexes, copper chelates, and other ions with accessible Lewis acidic centers.

4. The method of claim 1, wherein the ligand of the copper-based compound is selected from one or more of hydroxyl, water, ammonia, amine compounds, ethylenediamine, ethylenediaminetetraacetic acid, acetylacetone, and amino acids.

5. The method of claim 1, wherein, The porous polymer skeleton is a natural polymer material skeleton or a synthetic polymer skeleton. The natural polymer material skeleton is one of cellulose or its derivatives, chitosan or its derivatives, and the like. The synthetic polymer skeleton is one of polyvinylidene fluoride-co-hexafluoropropylene, polyacrylonitrile, polyimide, and the like.

6. The method of claim 1, wherein, The composition containing a cyclic ether monomer of step S3 further comprises a lithium salt or a plasticizing additive; The lithium salt includes one or more of LiPF6, LiBF4, LiTFSI, LiODFB, and the like; The plasticizing additive includes one or more of FEC, FEMC, PFPN, and the like.

7. A solid state electrolyte, characterized by, Prepared by the method of any one of claims 1-6.

8. An electrochemical device comprising a positive electrode, a negative electrode, and an electrolyte interposed therebetween, characterized by, The electrolyte is the solid-state electrolyte of claim 7.

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