Multi-site mof crosslinked solid state polymer electrolyte and preparation method and application thereof

Abstract

The application belongs to the technical field of electrolyte, and discloses a multi-site MOF cross-linked solid-state polymer electrolyte and a preparation method and application thereof, and comprises the following steps: (1) dissolving zirconium tetrachloride, benzoic acid and tetracarboxyphenyl porphyrin TCPP in a mixed solvent of N,N-dimethylformamide and water to obtain a zirconium-based MOF with a surface rich in multi-site cross-linking functional groups; (2) dissolving a mixture of one or more of polyethylene glycol, polytetrahydrofuran, polyimide, polyvinyl alcohol, polyacrylic acid, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer and polyoxyethylene polyoxypropylene ether block copolymer into a dispersion liquid; (3) adding isocyanate to the obtained solution, and then adding a polyurethane reaction catalyst to obtain a polymer solution; and (4) adding a lithium salt to the polymer solution, uniformly coating the obtained polymer composite solution on a polytetrafluoro plate to obtain a solid-state polymer electrolyte. The application improves stability.

Description

Technical Field

[0001] This invention belongs to the field of electrolyte-related technology, and more specifically, relates to a multi-site MOF crosslinked solid polymer electrolyte, its preparation method and application. Background Technology

[0002] Next-generation battery energy storage systems, characterized by high capacity, long lifespan, low cost, and high safety, are key research areas in major national projects such as "New Energy Vehicles" and "Energy Storage and Smart Grid Technology." High-energy-density lithium metal batteries, due to their ultra-high theoretical specific capacity (3860 mAh g / g), are particularly promising. -1 With its extremely negative electrochemical potential (-3.040V relative to the standard hydrogen electrode), it has become a next-generation high-energy-density energy storage system with great research value. Coupled with a high-voltage, high-specific-capacity cathode, it can further improve the energy density of the battery system, such as lithium cobalt oxide (Li / / LCO) and high-nickel ternary (Li / / NCM) battery systems.

[0003] However, lithium metal batteries based on traditional liquid electrolytes face serious challenges in practical applications: 1) Organic liquid carbonate / ether electrolytes are prone to leakage, flammability, and toxicity, leading to serious safety hazards; 2) Lithium metal is difficult to match with high-voltage nickel-cobalt-manganese ternary (LiNi) batteries. x Co y Mn 1-x-y 1) At the positive electrode, the electrolyte is prone to oxidative decomposition in the high-voltage region; 2) During charging / discharging, the growth of lithium dendrites and the pulverization of metallic lithium will continuously consume the electrolyte, eventually leading to battery short circuits, fires, or even explosions. Therefore, how to develop high-voltage lithium metal batteries that combine high specific energy and long lifespan is an urgent problem to be solved.

[0004] Inorganic solid-state electrolytes possess advantages such as high room-temperature ionic conductivity, wide electrochemical window, and stable properties. However, when used alone as electrolytes, they also suffer from problems such as high brittleness and high interfacial impedance with the positive and negative electrodes. Polymer solid-state electrolytes, composed of an organic polymer matrix and lithium salts, exhibit good electrode interfacial compatibility and flexibility, and hold promise for fundamentally overcoming the inherent shortcomings of liquid electrolytes. This allows for the matching of lithium metal anodes with high specific capacity or high voltage cathodes to create lithium metal batteries with higher energy density. However, they also face challenges such as low room-temperature ionic conductivity, poor mechanical strength and thermal stability, and a narrow electrochemical window.

[0005] However, in the design of polymer electrolyte structural parameters, there are still problems such as poor mechanical properties and low ionic conductivity. The literature suggests that adding inorganic nanofillers or plasticizers can reduce the ordered arrangement of polymer chains and improve the mechanical strength and room temperature ionic conductivity of solid polymer electrolytes. However, the relatively weak polymer-filler interaction in this strategy seriously reduces the mechanical properties of polymer electrolytes. At the same time, inorganic fillers are usually non-uniform in morphology or size and tend to agglomerate in the polymer matrix and undergo phase separation.

[0006] Therefore, an ideal polymer electrolyte should simultaneously meet the following requirements: 1) High lithium-ion conductivity, low electrode / electrolyte interface resistance, and high Li-ion conductivity at ambient temperature. + 2) Wide electrochemical stability window to match high-voltage cathodes and lithium metal anodes (>5V vs. Li / Li). + 3) High mechanical strength inhibits lithium dendrite growth; 4) Excellent flexibility and elasticity are suitable for flexible foldable batteries; 5) Good thermal stability ensures safe operation of the battery at high temperatures. Summary of the Invention

[0007] To address the above-mentioned deficiencies or improvement needs of existing technologies, this invention provides a multi-site MOF crosslinked solid polymer electrolyte, its preparation method, and its application. The preparation method provides a method for preparing a zirconium-based organometallic framework (Zr-MOF) MOF with multiple active hydrogen functional groups. The obtained zirconium-based organometallic framework is used as a multi-site crosslinking node and undergoes an addition polymerization reaction with an ether monomer to construct a three-dimensional crosslinked polyether polymer electrolyte with excellent mechanical properties, high ionic conductivity, and high voltage electrochemical stability.

[0008] To achieve the above objectives, according to one aspect of the present invention, a method for preparing a multi-site MOF crosslinked solid polymer electrolyte is provided, the method comprising the following steps:

[0009] (1) Zirconium tetrachloride, benzoic acid, tetracarboxyphenylporphyrin TCPP were dissolved in a mixed solvent of N,N-dimethylformamide and water and then reacted in a reaction vessel to obtain zirconium-based MOF with a surface rich in multi-site cross-linking functional groups.

[0010] (2) Dissolve a mixture of one or more of the following: polyethylene glycol, polytetrahydrofuran, polyimide, polyvinyl alcohol, polyacrylic acid, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer and polyoxyethylene polyoxypropylene ether block copolymer having active hydrogen functional groups into the dispersion of the zirconium-based MOF.

[0011] (3) After adding the isocyanate that can react with the active hydrogen functional group to the solution obtained in step (2), a polyurethane reaction catalyst is added to the resulting mixed solution to obtain a polymer solution.

[0012] (4) Add lithium salt to the polymer solution to obtain a uniform polymer composite solution, and uniformly coat the polymer composite solution onto a polytetrafluoroethylene plate to obtain a solid polymer electrolyte.

[0013] Further, zirconium tetrachloride, benzoic acid, and tetracarboxyphenylporphyrin TCPP were dissolved in a mixed solvent of N,N-dimethylformamide and water in a predetermined ratio, placed in a reaction vessel, reacted at 100℃~180℃ for 24 hours, centrifuged, and washed with ethanol to obtain zirconium-based MOF with a surface rich in multi-site cross-linking functional groups.

[0014] Further, the zirconium-based MOF is dispersed in a solvent to obtain a dispersion of the zirconium-based MOF; wherein the solvent used is one or more of N,N-dimethylformamide, N-methylpyrrolidone, N-methylformamide, dichloromethane, trichloromethane, and tetrahydrofuran, and the ratio of zirconium-based MOF to solvent is 1:5 to 1:100.

[0015] Furthermore, the mass ratio of zirconium tetrachloride, benzoic acid, and tetracarboxyphenylporphyrin TCPP used was 10:250:10. They were dissolved together in a mixed solvent of N,N-dimethylformamide and water in a volume ratio of 10:1. The mixture was placed in a reaction vessel and reacted at 120°C for 24 hours. After centrifugation and washing, zirconium-based MOF was obtained.

[0016] Furthermore, isocyanate is a symmetrical diisocyanate, a commonly used monomer in the synthesis of polyurethanes.

[0017] Further, the diisocyanate is one or more of hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, isoflurane diisocyanate, lysine diisocyanate, and triphenylmethane triisocyanate.

[0018] Furthermore, the polyurethane reaction catalyst is one of dibutyltin dilaurate, dibutyltin diacetate, zinc isooctanoate, bismuth isooctanoate, zinc neodecanoate, and bismuth neodecanoate; the lithium salt is one or more of lithium bis(oxalato)borate, lithium difluorooxalato)borate, lithium difluorophosphate, lithium tetrafluorooxalato)phosphate, lithium difluorophosphate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, and lithium nitrate.

[0019] The present invention also provides a multi-site MOF crosslinked solid polymer electrolyte, which is prepared by the preparation method of the multi-site MOF crosslinked solid polymer electrolyte described above.

[0020] Furthermore, the structural formula of the solid polymer electrolyte is:

[0021]

[0022] The present invention also provides an application of the multi-site MOF crosslinked solid polymer electrolyte as described above in a secondary battery.

[0023] In summary, compared with the prior art, the multi-site MOF crosslinked solid polymer electrolyte, its preparation method, and its application provided by the present invention have the following beneficial effects:

[0024] 1. Metal-organic frameworks, as multi-site cross-linking nodes, have advantages such as uniform size, rich structure, and precise geometric and crystal structure parameters.

[0025] 2. By copolymerizing multiple monomers with multi-site MOF crosslinking nodes, its organic-inorganic composite structure can break the ordered arrangement of polymer chains and reduce the crystallinity of polymer electrolytes.

[0026] 3. The introduction of abundant ether oxygen structures and hydroxyl functional groups into the polymer structure promotes lithium salt dissociation and lithium ion transport, significantly improving the conductivity of lithium ions at room temperature.

[0027] 4. The three-dimensional cross-linked network in the polymer electrolyte can improve mechanical strength and inhibit the growth of lithium dendrites in the negative electrode.

[0028] 5. Introducing electron-rich structures such as urethane groups, C=O groups on urea groups, and benzene rings into the polymer framework can preferentially provide electrons, prevent the destruction of ether oxygen structures, and thus improve the stability of the high-nickel ternary cathode and electrolyte interface, suppress the dissolution of transition metal ions during cycling, and address issues such as continuous voltage decay and oxygen release. Attached Figure Description

[0029] Figure 1 This is a schematic flowchart of a method for preparing a multi-site MOF crosslinked solid polymer electrolyte provided by the present invention;

[0030] Figure 2 In the diagrams, a and b are schematic diagrams of the reaction and molecular structure of the polymer electrolyte prepared in Example 10.

[0031] Figure 3 (a), (b), (c), and (d) are transmission electron micrographs of the zirconium-based MOFs prepared in Example 5 and Example 10, respectively.

[0032] Figure 4(a), (b), (c), (d), (e), and (f) in the figure are the elemental distribution diagrams of the zirconium-based MOFs prepared in Example 5 and Example 10, respectively.

[0033] Figure 5 a and b in the figure are scanning electron microscope images of the surface of the polymer electrolyte membranes prepared in Example 2 and Example 8, respectively.

[0034] Figure 6 This is a comparison chart of the tensile breaking strength of the polymer electrolyte membranes prepared in all embodiments;

[0035] Figure 7 This is a graph showing the cycle performance of a lithium-lithium symmetric battery assembled with the polymer electrolyte prepared in Example 3;

[0036] Figure 8 This is a graph showing the cycle performance of a lithium-lithium symmetric battery assembled with the polymer electrolyte prepared in Example 5;

[0037] Figure 9 This is a graph showing the cycle performance of the polymer electrolyte assembled lithium-lithium symmetric battery prepared in Example 10;

[0038] Figure 10 This is a graph showing the cycle performance of the polymer electrolyte assembled lithium-lithium symmetric battery prepared in Example 11;

[0039] Figure 11 This is a graph showing the cycle performance of a lithium metal battery assembled with the polymer electrolyte prepared in Example 5;

[0040] Figure 12 This is a graph showing the cycle performance of a lithium metal battery assembled with the polymer electrolyte prepared in Example 3;

[0041] Figure 13 This is a graph showing the cycle performance of a lithium metal battery assembled with the polymer electrolyte prepared in Example 6;

[0042] Figure 14 This is a graph showing the cycle performance of a lithium metal battery assembled with the polymer electrolyte prepared in Example 8;

[0043] Figure 15 This is a graph showing the cycle performance of a lithium metal battery assembled with the polymer electrolyte prepared in Example 10;

[0044] Figure 16 This is a graph showing the cycle performance of a lithium metal battery assembled with the polymer electrolyte prepared in Example 12. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0046] Please see Figure 1 This invention provides a method for preparing a multi-site MOF crosslinked solid polymer electrolyte. Compared with inorganic nanoparticles, the solid polymer electrolyte prepared by this method has the advantages of uniform size, rich structure, and designability due to the zirconium-based MOF. The excellent mechanical strength of the designed polymer electrolyte is attributed to the hyperbranched three-dimensional crosslinked network structure and the abundant intermolecular hydrogen bond interactions between urethane and urea groups. The introduction of abundant ether oxygen monomer structures and carbonyl oxygen functional groups into the polymer structure promotes lithium salt dissociation and lithium ion transport. At the same time, the crosslinking reaction is controlled to form electrochemically stable functional groups to improve the high voltage stability of the electrolyte. The constructed polymer electrolyte can be matched with high specific capacity lithium metal anodes and high voltage high-nickel ternary cathodes to improve problems such as transition metal ion dissolution, continuous voltage decay, and gas generation during cathode cycling.

[0047] The preparation method mainly includes the following steps:

[0048] Step 1: Zirconium tetrachloride, benzoic acid, and tetracarboxyphenylporphyrin TCPP are dissolved in a mixed solvent of N,N-dimethylformamide and water, and then placed in a reaction vessel to react and obtain zirconium-based MOFs with surface rich in multi-site cross-linking functional groups.

[0049] Specifically, zirconium tetrachloride, benzoic acid, and tetracarboxyphenylporphyrin (TCPP) are dissolved in a mixed solvent of N,N-dimethylformamide and water in a certain proportion. The solution is placed in a reaction vessel and reacted at 100°C–180°C (preferably 120°C) for 24 hours. After centrifugation, the solution is washed with ethanol to obtain a zirconium-based MOF with a surface rich in multi-site cross-linking functional groups. The zirconium-based MOF is then dispersed in a solvent to obtain a dispersion of the zirconium-based MOF. The solvent used is one or more of N,N-dimethylformamide, N-methylpyrrolidone, N-methylformamide, dichloromethane, trichloromethane, and tetrahydrofuran, and the ratio of zirconium-based MOF to solvent is 1:5 to 1:100.

[0050] In this embodiment, the mass ratio of zirconium tetrachloride, benzoic acid, and tetracarboxyphenylporphyrin TCPP is 10:250:10. They are dissolved together in a mixed solvent of N,N-dimethylformamide and water in a volume ratio of 10:1. The mixture is placed in a reaction vessel and reacted at 120°C for 24 hours. After centrifugation and washing, zirconium-based MOF is obtained.

[0051] Step 2: Dissolve a mixture of one or more of the following components with active hydrogen functional groups: polyethylene glycol, polytetrahydrofuran, polyimide, polyvinyl alcohol, polyacrylic acid, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, and polyoxyethylene polyoxypropylene ether block copolymer into the dispersion of the zirconium-based MOF.

[0052] Specifically, a mixture of one or more of the following: polyethylene glycol (PEG), polytetrahydrofuran (PTHF), polyimide (PEI), polyvinyl alcohol (PVA), polyacrylic acid (PAA), polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (PEO-PPO-PEO), and polyoxyethylene polyoxypropylene ether block copolymer (PEG-PPO-PEG) with active hydrogen functional groups is dissolved in the dispersion of zirconium-based MOF in step one.

[0053] Step 3: After adding the isocyanate that can react with the active hydrogen functional group to the solution obtained in step 2, a polyurethane reaction catalyst is added to the resulting mixed solution to obtain a polymer solution.

[0054] Specifically, a certain amount of polyurethane reaction catalyst is added to the obtained mixed solution, and the mixture is stirred in a sealed environment at a certain temperature for a period of time to obtain a viscous polymer solution. Then, a certain proportion of lithium salt is added to the obtained polymer solution, and the mixture is stirred rapidly to obtain a final homogeneous polymer composite solution.

[0055] Isocyanates are commonly used diisocyanates with good structural symmetry in the synthesis of polyurethanes, such as one or more of hexamethylene diisocyanate (HDI), toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (HMDI), isoflurone diisocyanate (IPDI), lysine diisocyanate (LDI), and triphenylmethane triisocyanate (TMDI). The dissolution temperature is controlled at 60℃, and the stirring time is 1–5 hours.

[0056] The polyurethane reaction catalyst is one of dibutyltin dilaurate, dibutyltin diacetate, zinc isooctanoate, bismuth isooctanoate, zinc neodecanoate, and bismuth neodecanoate. The lithium salt is one or more of lithium bis(oxalato)borate (LiBOB), lithium difluorooxalatoborate (LiDFOB), lithium difluorophosphate (LiP O2F2), lithium tetrafluorooxalatophosphate (LiFOP), lithium difluorophosphate (LiDFP), lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium nitrate (LiNO3).

[0057] Step four: Add lithium salt to the polymer solution to obtain a uniform polymer composite solution, and then uniformly coat the polymer composite solution onto a polytetrafluoroethylene plate to obtain a solid polymer electrolyte.

[0058] Specifically, the obtained polymer composite solution is uniformly coated onto a polytetrafluoroethylene (PTFE) plate using a film-stretching method, and then dried in an oven at 30°C–100°C (preferably 60°C) to form a film, which is the solid polymer electrolyte. The dried film sample is peeled off from the PTFE plate substrate and cut into circular pieces with a diameter of 19 mm, and its intrinsic electrochemical performance is tested.

[0059] In this embodiment, the dried membrane sample is peeled off from the polytetrafluoroethylene plate substrate. The thickness of the solid polymer electrolyte membrane obtained after drying is controlled to be 5μm to 100μm, and it is cut into a disc with a diameter of 19mm and its intrinsic electrochemical performance is tested.

[0060] After obtaining the solid polymer electrolyte, the process further includes assembling the obtained solid polymer electrolyte with a positive electrode and a lithium metal negative electrode to form a battery. The positive electrode material used is a lithium cobalt oxide or nickel-cobalt-manganese ternary positive electrode. The mass percentage of active material in the entire electrode is 80wt% to 95wt%, and the loading per unit area is 3 to 20 mg / cm². -2 (preferably 3-8 mg cm) -2 No additional liquids or electrolytes are required when assembling the battery.

[0061] This invention also provides a multi-site MOF crosslinked solid polymer electrolyte, which is prepared using the preparation method of the multi-site MOF crosslinked solid polymer electrolyte described above. This invention also provides an application of the multi-site MOF crosslinked solid polymer electrolyte described above in a secondary battery. The structural formula of the solid polymer electrolyte is as follows:

[0062]

[0063] The present invention will be further described in detail below with reference to several specific embodiments.

[0064] Example 1

[0065] The preparation method of a multi-site MOF crosslinked solid polymer electrolyte provided in Example 1 of this invention mainly includes the following steps:

[0066] 1) Weigh 100 mg of zirconium tetrachloride and 2.5 g of benzoic acid and sonicate them into 20 mL of N,N-dimethylformamide. Add 2 mL of water to prepare a homogeneous and transparent solution. Weigh 100 mg of tetracarboxyphenylporphyrin (TCPP) and rapidly sonicate it until the solution turns dark green. Place the solution in a reaction vessel and react at 100 °C for 24 hours. After centrifugation and washing three times with ethanol, sonicate it into N,N-dimethylformamide for later use at a concentration of 10 mg / mL. -1 .

[0067] 2) Take 10 mL of the obtained solution, add 2.0 g of polyethylene glycol (PEG4000) monomer with active hydrogen functional group, add 0.25 g of toluene diisocyanate (TDI) dropwise, stir to dissolve evenly, and add 5 μL of initiator dibutyltin dilaurate.

[0068] 3) Add 1.0 g of lithium salt lithium tetrafluorooxalate phosphate (LiFOP) to the obtained solution, control the dissolution temperature at 30℃, and stir for 2 h until the solution is uniform and transparent;

[0069] 4) The composite solution is uniformly flowed along the polytetrafluoroethylene plate to form a film, dried, and cut into circular pieces with a diameter of 19 mm. The thickness of the resulting solid polymer electrolyte membrane is controlled to be 25 μm.

[0070] 5) The obtained polymer electrolyte film was matched with lithium metal and lithium cobalt oxide cathodes, wherein the mass percentage of active material in the entire cathode was 85 wt%, and the loading per unit area was 12 mg / cm². -2 The battery was assembled and allowed to stand for 5 hours before its electrochemical performance was tested.

[0071] Example 2

[0072] Please see Figure 2 and Figure 5 The preparation method of a multi-site MOF crosslinked solid polymer electrolyte provided in Example 2 of this invention mainly includes the following steps:

[0073] 1) Weigh 100 mg of zirconium tetrachloride and 2.5 g of benzoic acid and sonicate them into 20 mL of N,N-dimethylformamide. Add 2 mL of water to prepare a homogeneous and transparent solution. Weigh 100 mg of tetracarboxyphenylporphyrin (TCPP) and rapidly sonicate it until the solution turns dark green. Place the solution in a reaction vessel and react at 120 °C for 24 hours. After centrifugation and washing three times with ethanol, sonicate it into N,N-dimethylformamide for later use. The concentration should be 20 mg / mL. -1 ;

[0074] 2) Take 10 mL of the obtained solution, add 1.0 g of polyimide (PEI) monomer with active hydrogen functional group, add 0.23 g of isoflurane diisocyanate (IPDI) dropwise, stir to dissolve evenly, and add 10 μL of initiator dibutyltin diacetate.

[0075] 3) Add 1.8g of lithium salt lithium tetrafluoroborate (LiBF4) to the obtained solution, control the dissolution temperature at 60℃, and stir for 2 hours until the solution is uniform and transparent;

[0076] 4) The composite solution is uniformly flowed along the polytetrafluoroethylene plate to form a film, dried, and cut into circular pieces with a diameter of 19 mm. The thickness of the resulting solid polymer electrolyte membrane is controlled to be 30 μm.

[0077] 5) The obtained polymer electrolyte film was matched with lithium metal and lithium cobalt oxide cathodes, wherein the active material content in the entire cathode was 80 wt% and the loading per unit area was 5 mg / cm². -2 The battery was assembled and allowed to stand for 5 hours before its electrochemical performance was tested.

[0078] Example 3

[0079] Please see Figure 7 and Figure 12 The preparation method of a multi-site MOF crosslinked solid polymer electrolyte provided in Example 3 of this invention mainly includes the following steps:

[0080] 1) Weigh 100 mg of zirconium tetrachloride and 2.5 g of benzoic acid and sonicate them into 20 mL of N,N-dimethylformamide. Add 2 mL of water to prepare a homogeneous and transparent solution. Weigh 100 mg of tetracarboxyphenylporphyrin (TCPP) and rapidly sonicate it until the solution turns dark green. Place the solution in a reaction vessel and react at 120 °C for 24 hours. After centrifugation and washing three times with ethanol, sonicate the solution into N,N-dimethylformamide for later use at a concentration of 15 mg / mL. -1 ;

[0081] 2) Take 6 mL of the obtained solution, add 3 g of polyvinyl alcohol (PVA) monomer with active hydrogen functional group, add 0.3 g of dicyclohexylmethane diisocyanate (HMDI) dropwise, stir to dissolve evenly, and add 8 μL of zinc isooctanoate.

[0082] 3) Add 2.6g of lithium salt lithium bisfluorosulfonylimide (LiFSI) to the obtained solution, control the dissolution temperature at 60℃, and stir for 2h;

[0083] 4) The composite solution is uniformly flowed onto the polytetrafluoroethylene plate to form a film, dried, and cut into circular pieces with a diameter of 19 mm. The thickness of the resulting solid polymer electrolyte membrane is controlled to be 35 μm.

[0084] 5) The obtained polymer electrolyte film was matched with a lithium metal and nickel-cobalt-manganese 622 cathode, wherein the active material content in the entire cathode was 90 wt% and the loading per unit area was 8 mg / cm². -2 The battery was assembled and allowed to stand for 5 hours before its electrochemical performance was tested.

[0085] Example 4

[0086] The preparation method of a multi-site MOF crosslinked solid polymer electrolyte provided in Example 4 of this invention mainly includes the following steps:

[0087] 1) Weigh 100 mg of zirconium tetrachloride and 2.5 g of benzoic acid and sonicate them into 20 mL of N,N-dimethylformamide. Add 2 mL of water to prepare a homogeneous and transparent solution. Weigh 100 mg of tetracarboxyphenylporphyrin (TCPP) and rapidly sonicate it until the solution turns dark green. Place the solution in a reaction vessel and react at 120 °C for 24 hours. After centrifugation and washing three times with ethanol, sonicate it into N,N-dimethylformamide for later use. The concentration should be 20 mg / mL. -1 ;

[0088] 2) Take 5 mL of the obtained solution, add 3.0 g of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (PEO-PPO-PEO) with active hydrogen functional groups, add 0.25 g of triphenylmethane triisocyanate (TMDI) dropwise, stir to dissolve evenly, and add 8 μL of bismuth isooctanoate initiator.

[0089] 3) Add 2g of lithium salt lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) to the obtained solution, control the dissolution temperature at 60℃, and stir for 2h;

[0090] 4) The composite solution is uniformly flowed onto the polytetrafluoroethylene plate to form a film, dried, and cut into circular pieces with a diameter of 19 mm. The thickness of the resulting solid polymer electrolyte membrane is controlled to be 35 μm.

[0091] 5) The obtained polymer electrolyte film was matched with a lithium metal and nickel-cobalt-manganese 811 cathode, wherein the mass percentage of active material in the entire cathode was 88 wt%, and the loading per unit area was 5 mg / cm². -2 The battery was assembled and allowed to stand for 5 hours before its electrochemical performance was tested.

[0092] Example 5

[0093] Please see Figure 3 , Figure 4 , Figure 8 and Figure 11 The preparation method of a multi-site MOF crosslinked solid polymer electrolyte provided in Example 5 of this invention mainly includes the following steps:

[0094] 1) Weigh 100 mg of zirconium tetrachloride and 2.5 g of benzoic acid and sonicate them into 20 mL of N,N-dimethylformamide. Add 2 mL of water to prepare a homogeneous and transparent solution. Weigh 100 mg of tetracarboxyphenylporphyrin (TCPP) and rapidly sonicate it until the solution turns dark green. Place the solution in a reaction vessel and react at 120 °C for 24 hours. After centrifugation and washing three times with ethanol, sonicate it into N,N-dimethylformamide for later use. The concentration should be 6 mg / mL. -1 ;

[0095] 2) Take 60 mL of the obtained solution, add 2.5 g of polytetrahydrofuran (PTHF1000) monomer with active hydrogen functional group, add 0.25 g of diphenylmethane diisocyanate (MDI) dropwise, stir to dissolve evenly, and add 5 μL of zinc neodecanoate initiator.

[0096] 3) Add 1.0 g of lithium salt lithium hexafluorophosphate (LiPF6) to the obtained solution, control the dissolution temperature at 60℃, and stir for 2 h until the solution is uniform and transparent;

[0097] 4) The composite solution is uniformly flowed along the polytetrafluoroethylene plate to form a film, dried, and cut into circular pieces with a diameter of 19 mm. The thickness of the resulting solid polymer electrolyte membrane is controlled to be 40 μm.

[0098] 5) The obtained polymer electrolyte film was matched with a lithium metal and nickel-cobalt-manganese 811 cathode, wherein the mass percentage of active material in the entire cathode was 93 wt%, and the loading per unit area was 10 mg / cm². -2 The battery was assembled and allowed to stand for 5 hours before its electrochemical performance was tested.

[0099] Example 6

[0100] The preparation method of a multi-site MOF crosslinked solid polymer electrolyte provided in Example 6 of this invention mainly includes the following steps:

[0101] 1) Weigh 100 mg of zirconium tetrachloride and 2.5 g of benzoic acid and sonicate them into 20 mL of N,N-dimethylformamide. Add 2 mL of water to prepare a homogeneous and transparent solution. Weigh 100 mg of tetracarboxyphenylporphyrin (TCPP) and rapidly sonicate it until the solution turns dark green. Place the solution in a reaction vessel and react at 120 °C for 24 hours. After centrifugation and washing three times with ethanol, sonicate the solution into N,N-dimethylformamide for later use. The concentration should be 8 mg / mL. -1 ;

[0102] 2) Take 10 mL of the obtained solution, add 3.0 g of polyethylene glycol (PEG2000) monomer with active hydrogen functional group, add 0.2 g of toluene diisocyanate (TDI) dropwise, stir to dissolve evenly, and add 5 μL of initiator dibutyltin dilaurate.

[0103] 3) Add 1.4g of lithium difluorophosphate (LiPO2F2) to the obtained solution, control the dissolution temperature at 60℃, and stir for 2h until the solution is uniform and transparent;

[0104] 4) The composite solution is uniformly flowed along the polytetrafluoroethylene plate to form a film, dried, and cut into circular pieces with a diameter of 19 mm. The thickness of the resulting solid polymer electrolyte membrane is controlled to be 45 μm.

[0105] 5) The obtained polymer electrolyte film was matched with a lithium metal and nickel-cobalt-manganese 811 cathode, wherein the mass percentage of active material in the entire cathode was 96 wt%, and the loading per unit area was 8 mg / cm². -2 The battery was assembled and allowed to stand for 5 hours before its electrochemical performance was tested.

[0106] Example 7

[0107] Please see Figure 6 The preparation method of a multi-site MOF crosslinked solid polymer electrolyte provided in Example 7 of this invention mainly includes the following steps:

[0108] 1) Weigh 100 mg of zirconium tetrachloride and 2.5 g of benzoic acid and sonicate them into 20 mL of N,N-dimethylformamide. Add 2 mL of water to prepare a homogeneous and transparent solution. Weigh 100 mg of tetracarboxyphenylporphyrin (TCPP) and rapidly sonicate it until the solution turns dark green. Place the solution in a reaction vessel and react at 120 °C for 24 hours. After centrifugation and washing three times with ethanol, sonicate it into N,N-dimethylformamide for later use at a concentration of 10 mg / mL. -1 ;

[0109] 2) Take 10 mL of the obtained solution, add 4.0 g of monomeric polyoxyethylene polyoxypropylene ether block copolymer (PEG-PPO-PEG) with active hydrogen functional groups, add 0.45 g of hexamethylene diisocyanate (HDI) dropwise, stir to dissolve evenly, and add 5 μL of initiator dibutyltin dilaurate.

[0110] 3) Add 1.0g of lithium salt lithium bis(oxalato)borate (LiBOB) to the obtained solution, control the dissolution temperature at 60℃, and stir for 2 hours until the solution is uniform and transparent.

[0111] 4) The composite solution is uniformly flowed onto the polytetrafluoroethylene plate to form a film, dried, and cut into circular pieces with a diameter of 19 mm. The thickness of the resulting solid polymer electrolyte membrane is controlled to be 35 μm.

[0112] 5) The obtained polymer electrolyte film was matched with a lithium metal and nickel-cobalt-manganese 811 cathode, wherein the mass percentage of active material in the entire cathode was 88 wt%, and the loading per unit area was 10 mg / cm². -2 The battery was assembled and allowed to stand for 5 hours before its electrochemical performance was tested.

[0113] Example 8

[0114] Please see Figure 14 The preparation method of a multi-site MOF crosslinked solid polymer electrolyte provided in Example 8 of this invention mainly includes the following steps:

[0115] 1) Weigh 100 mg of zirconium tetrachloride and 2.5 g of benzoic acid and sonicate them into 20 mL of N,N-dimethylformamide. Add 2 mL of water to prepare a homogeneous and transparent solution. Weigh 100 mg of tetracarboxyphenylporphyrin (TCPP) and rapidly sonicate it until the solution turns dark green. Place the solution in a reaction vessel and react at 120 °C for 24 hours. After centrifugation and washing three times with ethanol, sonicate it into N,N-dimethylformamide for later use at a concentration of 10 mg / mL. -1 ;

[0116] 2) Take 10 mL of the obtained solution, add 3.0 g of polyvinyl alcohol (PVA) monomer with active hydrogen functional group, add 0.35 g of lysine diisocyanate (LDI) dropwise, stir to dissolve evenly, and add 8 μL of initiator dibutyltin dilaurate.

[0117] 3) Add 2.0g of lithium difluorophosphate (LiDFP) to the obtained solution, control the dissolution temperature at 60℃, and stir for 2h until the solution is uniform and transparent;

[0118] 4) The composite solution is uniformly flowed along the polytetrafluoroethylene plate to form a film, dried, and cut into circular pieces with a diameter of 19 mm. The thickness of the resulting solid polymer electrolyte membrane is controlled to be 22 μm.

[0119] 5) The obtained polymer electrolyte film was matched with a lithium metal and nickel-cobalt-manganese 811 cathode, wherein the mass percentage of active material in the entire cathode was 80 wt%, and the loading per unit area was 6 mg / cm². -2 The battery was assembled and allowed to stand for 5 hours before its electrochemical performance was tested.

[0120] Example 9

[0121] The preparation method of a multi-site MOF crosslinked solid polymer electrolyte provided in Example 9 of this invention mainly includes the following steps:

[0122] 1) Weigh 100 mg of zirconium tetrachloride and 2.5 g of benzoic acid and sonicate them into 20 mL of N,N-dimethylformamide. Add 2 mL of water to prepare a homogeneous and transparent solution. Weigh 100 mg of tetracarboxyphenylporphyrin (TCPP) and rapidly sonicate it until the solution turns dark green. Place the solution in a reaction vessel and react at 120 °C for 24 hours. After centrifugation and washing three times with ethanol, sonicate it into N,N-dimethylformamide for later use at a concentration of 5 mg / mL. -1 ;

[0123] 2) Take 10 mL of the obtained solution, add 4.5 g of monomer polyacrylic acid (PAA) with active hydrogen functional group, add 0.25 g of toluene diisocyanate (TDI) dropwise, stir to dissolve evenly, and add 8 μL of initiator bismuth neodecanoate.

[0124] 3) Add 3.0 g of lithium salt lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) to the obtained solution, control the dissolution temperature at 60℃, and stir for 2 h until the solution is uniform and transparent;

[0125] 4) The composite solution is uniformly flowed along the polytetrafluoroethylene plate to form a film, dried, and cut into circular pieces with a diameter of 19 mm. The thickness of the resulting solid polymer electrolyte membrane is controlled to be 30 μm.

[0126] 5) The obtained polymer electrolyte film was matched with a lithium metal and nickel-cobalt-manganese 622 cathode, wherein the mass percentage of active material in the entire cathode was 85 wt%, and the loading per unit area was 12 mg / cm². -2 The battery was assembled and allowed to stand for 5 hours before its electrochemical performance was tested.

[0127] Example 10

[0128] Please see Figure 2 , Figure 3 , Figure 6 , Figure 9 and 15 The preparation method of a multi-site MOF crosslinked solid polymer electrolyte provided in Example 10 of this invention mainly includes the following steps:

[0129] 1) Weigh 100 mg of zirconium tetrachloride and 2.5 g of benzoic acid and sonicate them into 20 mL of N,N-dimethylformamide. Add 2 mL of water to prepare a homogeneous and transparent solution. Weigh 100 mg of tetracarboxyphenylporphyrin (TCPP) and rapidly sonicate it until the solution turns dark green. Place the solution in a reaction vessel and react at 120 °C for 24 hours. After centrifugation and washing three times with ethanol, sonicate it into N,N-dimethylformamide for later use at a concentration of 10 mg / mL.-1 ;

[0130] 2) Take 7 mL of the obtained solution, add 2.0 g of polyethylene glycol (PEG2000) monomer with active hydrogen functional group, add 0.25 g of dicyclohexylmethane diisocyanate (HMDI) dropwise, stir to dissolve evenly, and add 5 μL of initiator dibutyltin dilaurate.

[0131] 3) Add 1.5g of lithium salt lithium bisfluorosulfonylimide (LiFSI) to the obtained solution, control the dissolution temperature at 60℃, and stir for 2h until the solution is uniform and transparent;

[0132] 4) The composite solution is uniformly flowed along the polytetrafluoroethylene plate to form a film, dried, and cut into circular pieces with a diameter of 19 mm. The thickness of the obtained solid polymer electrolyte membrane is controlled to be 33 μm.

[0133] 5) The obtained polymer electrolyte film was matched with a lithium metal and nickel-cobalt-manganese 811 cathode, wherein the mass percentage of active material in the entire cathode was 90 wt%, and the loading per unit area was 10 mg / cm². -2 The battery was assembled and allowed to stand for 5 hours before its electrochemical performance was tested.

[0134] Example 11

[0135] The preparation method of a multi-site MOF crosslinked solid polymer electrolyte provided in Example 11 of this invention mainly includes the following steps:

[0136] 1) Weigh 100 mg of zirconium tetrachloride and 2.5 g of benzoic acid and sonicate them into 20 mL of N,N-dimethylformamide. Add 2 mL of water to prepare a homogeneous and transparent solution. Weigh 100 mg of tetracarboxyphenylporphyrin (TCPP) and rapidly sonicate it until the solution turns dark green. Place the solution in a reaction vessel and react at 140 °C for 24 hours. After centrifugation and washing three times with ethanol, sonicate the solution into N,N-dimethylformamide for later use at a concentration of 10 mg / mL. -1 ;

[0137] 2) Take 5 mL of the obtained solution, add 3.5 g of polyimide (PEI) monomer with active hydrogen functional group, add 0.25 g of toluene diisocyanate (TDI) dropwise, stir to dissolve evenly, and add 10 μL of initiator dibutyltin diacetate.

[0138] 3) Add 2.0g of lithium salt lithium bis(oxalato)borate (LiBOB) to the obtained solution, control the dissolution temperature at 50℃, and stir for 2 hours until the solution is uniform and transparent;

[0139] 4) The composite solution is uniformly flowed along the polytetrafluoroethylene plate to form a film, dried, and cut into circular pieces with a diameter of 19 mm. The thickness of the resulting solid polymer electrolyte membrane is controlled to be 25 μm.

[0140] 5) The obtained polymer electrolyte film was matched with a lithium metal and nickel-cobalt-manganese 622 cathode, wherein the mass percentage of active material in the entire cathode was 86 wt%, and the loading per unit area was 5 mg / cm². -2 The battery was assembled and allowed to stand for 5 hours before its electrochemical performance was tested.

[0141] Example 12

[0142] Please see Figure 16 The preparation method of a multi-site MOF crosslinked solid polymer electrolyte provided in Example 12 of this invention mainly includes the following steps:

[0143] 1) Weigh 100 mg of zirconium tetrachloride and 2.5 g of benzoic acid and sonicate them into 20 mL of N,N-dimethylformamide. Add 2 mL of water to prepare a homogeneous and transparent solution. Weigh 100 mg of tetracarboxyphenylporphyrin (TCPP) and rapidly sonicate it until the solution turns dark green. Place the solution in a reaction vessel and react at 160 °C for 24 hours. After centrifugation and washing three times with ethanol, sonicate it into N,N-dimethylformamide for later use at a concentration of 10 mg / mL. -1 ;

[0144] 2) Take 4 mL of the obtained solution, add 2.0 g of polytetrahydrofuran (PTHF2000) monomer with active hydrogen functional group, add 0.35 g of dicyclohexylmethane diisocyanate (HMDI) dropwise, stir to dissolve evenly, and add 5 μL of initiator dibutyltin dilaurate.

[0145] 3) Add 1.5g of lithium salt lithium bisfluorosulfonylimide (LiFSI) to the obtained solution, control the dissolution temperature at 80℃, and stir for 2h until the solution is uniform and transparent;

[0146] 4) The composite solution is uniformly flowed along the polytetrafluoroethylene plate to form a film, dried, and cut into circular pieces with a diameter of 19 mm. The thickness of the obtained solid polymer electrolyte membrane is controlled to be 33 μm.

[0147] 5) The obtained polymer electrolyte film was matched with a lithium metal and nickel-cobalt-manganese 811 cathode, wherein the mass percentage of active material in the entire cathode was 85 wt%, and the loading per unit area was 12 mg / cm². -2 The battery was assembled and allowed to stand for 5 hours before its electrochemical performance was tested.

[0148] Based on the above preferred embodiments, it can be concluded that the polymer electrolyte shown in Example 10, which uses polyethylene glycol (PEG2000) and dicyclohexylmethane diisocyanate (HMDI) as reactants, zirconium-based MOF as crosslinking nodes, and lithium bisfluorosulfonylimide (LiFSI) as a crosslinking agent, has higher mechanical strength and ionic conductivity. This is also attributed to the fact that the polymer obtained by multiple reaction sites is crosslinked, and the three-dimensional crosslinked structure itself has better mechanical properties. At the same time, the abundant ether oxygen structure can coordinate and transport lithium ions more quickly. The solid-state nickel-cobalt-manganese ternary battery assembled with this polymer electrolyte can stably cycle 800 times and has a high capacity retention rate.

[0149] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a multi-site MOF cross-linked solid state polymer electrolyte, characterized by, The preparation method comprises the following steps: (1) dissolving zirconium tetrachloride, benzoic acid and tetra-carboxyphenyl porphyrin TCPP in a mixed solvent of N,N-dimethylformamide and water in a predetermined proportion, placing in a reaction kettle, and reacting at 100-180°C for 24 hours to obtain a zirconium-based MOF with a surface rich in multi-site cross-linking functional groups; (2) dissolving a mixture of one or more of polyethylene glycol, polytetrahydrofuran, polyimide, polyvinyl alcohol, polyacrylic acid, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer and polyoxyethylene polyoxypropylene ether block copolymer with active hydrogen functional groups into a dispersion of the zirconium-based MOF; (3) adding isocyanate capable of reacting with the active hydrogen functional group to the solution obtained in step (2), and then adding a polyurethane reaction catalyst to the obtained mixed solution to obtain a polymer solution; (4) adding a lithium salt to the polymer solution to obtain a uniform polymer composite solution, uniformly coating the polymer composite solution on a polytetrafluoro plate, and then obtaining a solid-state polymer electrolyte.

2. The method for preparing the multi-site MOF crosslinked solid polymer electrolyte as described in claim 1, characterized in that: Zirconium tetrachloride, benzoic acid and tetra-carboxyphenyl porphyrin TCPP are dissolved in a mixed solvent of N,N-dimethylformamide and water in a predetermined proportion, placed in a reaction kettle, and centrifuged after reacting at 100-180°C for 24 hours, and washed with ethanol to obtain a zirconium-based MOF with a surface rich in multi-site cross-linking functional groups.

3. The method for preparing the multi-site MOF crosslinked solid polymer electrolyte as described in claim 1, characterized in that: The zirconium-based MOF is dispersed in a solvent to obtain a dispersion of the zirconium-based MOF; wherein the solvent used is one or more of N,N-dimethylformamide, N-methylpyrrolidone, N-methylformamide, dichloromethane, trichloromethane and tetrahydrofuran, and the ratio of the zirconium-based MOF to the solvent is 1:5-1:

100.

4. The method for preparing the multi-site MOF crosslinked solid polymer electrolyte as described in claim 2, characterized in that: The mass ratio of the zirconium tetrachloride, benzoic acid and tetra-carboxyphenyl porphyrin TCPP used is 10:250:10, which are collectively dissolved in a mixed solvent of N,N-dimethylformamide and water in a volume ratio of 10:1, placed in a reaction kettle, reacted at 120°C for 24 hours, and obtained after centrifugation and washing to obtain a zirconium-based MOF.

5. The method of making a multi-site MOF cross-linked solid state polymer electrolyte according to any one of claims 1-4, wherein: The isocyanate is a commonly used monomer for synthesizing polyurethane, and the structure of the isocyanate is symmetrical diisocyanate.

6. The method for preparing the multi-site MOF crosslinked solid polymer electrolyte as described in claim 5, characterized in that: The diisocyanate is one or more of hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, lysine diisocyanate and triphenylmethane triisocyanate.

7. The method of making a multi-site MOF cross-linked solid state polymer electrolyte according to any one of claims 1-4, wherein: The polyurethane reaction catalyst is one of dibutyltin dilaurate, dibutyltin diacetate, zinc isooctoate, bismuth isooctoate, zinc neodecanoate and bismuth neodecanoate; and the lithium salt is one or more of lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium difluorophosphate, lithium tetrafluoro(oxalato)phosphate, lithium difluorophosphate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(trifluoromethylsulfonyl)imide, lithium bis(fluorosulfonyl)imide and lithium nitrate.

8. A multi-site MOF cross-linked solid state polymer electrolyte characterized by: The solid-state polymer electrolyte is prepared by the method for preparing a multi-site MOF cross-linked solid-state polymer electrolyte according to any one of claims 1-7.

9. The multi-site MOF crosslinked solid state polymer electrolyte of claim 8, wherein: The structural formula of the solid-state polymer electrolyte is:

10. Use of the multi-site MOF cross-linked solid-state polymer electrolyte according to any one of claims 8-9 in a secondary battery.

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