Solid polymer electrolyte membrane containing orotic acid, preparation method thereof and application thereof

Abstract

The present invention belongs to the technical field of solid-state lithium batteries and relates to a solid polymer electrolyte membrane containing orotic acid, a preparation method thereof, and an application thereof in lithium metal batteries. The solid polymer electrolyte membrane comprises a polymer matrix, a conductive lithium salt, and orotic acid. The present invention introduces orotic acid into the solid polymer electrolyte to increase the interfacial compatibility between the polymer electrolyte membrane and metallic lithium, thereby improving the stability of the lithium negative electrode. During the cycle, LiN3 produced by the decomposition of orotic acid is present at the interface between lithium metal and the electrolyte membrane, inhibiting the growth of lithium dendrites, improving the stability and ion conductivity of the interface, and significantly improving the Li / PEO interface. At the same time, the specific capacity of the battery assembled with the polymer electrolyte containing orotic acid is also improved. Orotic acid is abundant in source, low in price, and has high economic benefits. In addition, the preparation process of the polymer solid electrolyte containing orotic acid of the present invention is mature, low in cost, and adopts a casting method for film formation, which is simple to prepare and suitable for large-scale production.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid-state lithium batteries and relates to a solid polymer electrolyte membrane containing orotic acid, a preparation method thereof and an application thereof in lithium metal batteries. Background Art

[0002] Lithium-ion batteries, as a representative energy storage device, offer numerous advantages, such as chemical stability, long cycle life, and high energy density, making them more widely used than other battery types. However, traditional lithium-ion batteries present serious safety issues, including the vulnerability of the positive and negative electrodes to short circuits, which can cause explosions. Current lithium secondary battery electrolytes consist of lithium salts dissolved in solvents such as ethylene carbonate (EC) and dimethyl carbonate (DMC). However, carbonates have high vapor pressures and are flammable when exposed to fire, posing significant safety concerns. Therefore, the electrolyte is a major factor affecting the safety of lithium secondary batteries. Compared to traditional liquid batteries, solid-state batteries utilize solid electrolytes instead of organic electrolytes. Solid-state electrolytes offer the following advantages: First, they contain no liquid components; the entire system is solid, eliminating safety concerns. Second, they are lighter, simplifying the structure and reducing the weight of the battery by replacing the liquid electrolyte and separator in the original system with a solid electrolyte. Third, the battery can be designed in any desired shape.

[0003] Solid-state electrolytes can be divided into polymer electrolytes, inorganic electrolytes, composite electrolytes, and other system electrolytes based on their components. Polymer electrolytes are electrolytes containing polymer materials that conduct electricity like liquids, typically consisting of polymers and conductive lithium salts. Common polymer electrolyte matrices include polyethylene oxide (PEO), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), and polymethacrylate (PMMA), with polyethylene oxide-based polymer electrolytes being the most representative.

[0004] PEO-based solid electrolytes have high electrical conductivity, stable chemical properties, good film-forming properties, can be prepared on a large scale, and have great commercial potential. Among the many metal lithium salts, people have widely studied the addition of conductive lithium salts (LiTFSI) to PEO. However, even so, the room temperature ionic conductivity of PEO-based polymer electrolytes is only 10 -5 S cm -1 , far less than the conductivity of liquid electrolyte 10 -2 S cm -1 to 10 -3 S cm -1, therefore the research that improves the ionic conductivity of PEO electrolyte is very important. Simultaneously in the cycle process of battery, PEO electrolyte can produce irreversible side reaction with metallic lithium, and the interface state is unstable, easily produces lithium dendrite, causes battery to have short circuit phenomenon, thus can't obtain PEO-based solid-state battery with long cycle life. Therefore, for some problems existing in polymer electrolyte, the present invention modifies PEO by adding small molecule protein orotic acid, thereby improves the ionic conductivity of electrolyte, improves the interface stability of solid electrolyte and electrode, promotes the capacity and cyclic stability of solid-state battery, has unique advantages and characteristics in modified solid polymer electrolyte. Summary of the Invention

[0005] The purpose of the present invention is to solve the problems of the prior art and provide a solid polymer electrolyte containing orotic acid, a preparation method thereof and an application thereof as a solid lithium metal battery material.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] The invention provides a solid polymer electrolyte membrane containing orotic acid. The solid polymer electrolyte membrane comprises a polymer matrix, a conductive lithium salt and orotic acid.

[0008] In the present invention, the structural formula of orotic acid is:

[0009]

[0010] Preferably, the polymer matrix is ​​polyethylene oxide, more preferably, the molecular weight of the polyethylene oxide is between 500,000 and 1.2 million, more preferably, the molecular weight of the polyethylene oxide is 600,000.

[0011] Preferably, the conductive lithium salt is selected from LiTFSI, LiFSI, LiClO4, LiBOB, LiAsF6, and LiBF4. More preferably, the conductive lithium salt is LiTFSI.

[0012] Preferably, the ratio of the polyethylene oxide to the conductive lithium salt is (15-25):1, more preferably 20:1, in terms of the molar ratio of EO (ethylene oxide):Li.

[0013] Preferably, the mass of the orotic acid is 1-15% of the total mass of the polymer matrix, the conductive lithium salt and the orotic acid. More preferably, the mass of the orotic acid is 7% of the total mass of the polyethylene oxide, the conductive lithium salt and the orotic acid.

[0014] The present invention also provides a method for preparing the above-mentioned solid polymer electrolyte membrane containing orotic acid, comprising the following steps:

[0015] (1) mixing a polymer matrix, a conductive lithium salt, orotic acid, and a solvent to form a casting solution;

[0016] (2) The casting solution is poured into a mold and the solvent is removed by drying to obtain a solid polymer electrolyte membrane.

[0017] In the present invention, steps (1) and (2) need to be performed under the condition that the moisture content is less than 0.1 ppm to prevent deliquescence of the conductive lithium salt such as LiTFSI, and further ensure the smooth progress of the reaction.

[0018] In the present invention, in steps (1) and (2), the polymer matrix, the conductive lithium salt and the orotic acid need to be dried before use; more preferably, the polyethylene oxide and the orotic acid need to be dried at 50-70°C for 24-48 hours, and the conductive lithium salt needs to be dried at 100-120°C for not less than 48 hours.

[0019] Preferably, the solvent in step (1) is N,N-dimethylformamide; more preferably, the solvent is N,N-dimethylformamide having a water volume content of less than 0.03%.

[0020] Preferably, in step (1), the mass ratio of the solvent to the polymer matrix is ​​(10-50):1.

[0021] Preferably, the stirring time after mixing in step (1) is not less than 24 hours to further mix the mixed solution. More preferably, the stirring temperature is 30-60° C. and the stirring time is not less than 24 hours to further promote the dissolution of orotic acid.

[0022] Preferably, the mold in step (2) is a polytetrafluoroethylene mold. More preferably, the size of the polytetrafluoroethylene mold is determined according to the size of the electrolyte actually required.

[0023] Preferably, the drying in step (2) includes: standing at room temperature for 3-5 hours, and after some of the solvent evaporates, heating at 30-60°C for 15-30 hours for pre-drying, and then placing in a vacuum oven at 80°C for 5-15 hours to completely dry the solvent. After the solution is poured into the mold, standing at room temperature allows the solution to have time to transition to room temperature, allowing the solution to be more evenly distributed, further avoiding the generation of bubbles during heating, and preventing holes in the electrolyte membrane.

[0024] Preferably, the thickness of the solid polymer electrolyte membrane prepared by the present invention is controlled between 60-120 microns. More preferably, the thickness of the electrolyte membrane is regulated by pouring a predetermined amount of the prepared solution into a mold box of 8 cm×4 cm.

[0025] The present invention also provides an application of the solid polymer electrolyte membrane containing orotic acid as a lithium metal solid electrolyte.

[0026] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in: the present invention introduces orotic acid into the solid polymer electrolyte, and the orotic acid increases the interfacial compatibility between the polymer electrolyte membrane and metallic lithium, thereby improving the stability of the lithium negative electrode. LiN3 produced by the decomposition of orotic acid during the circulation process is present at the interface between lithium metal and the electrolyte membrane, which can inhibit the growth of lithium dendrites, enhance the stability and ion conductivity of the interface, and has been proven to significantly improve the Li / PEO interface. At the same time, the specific capacity of the all-solid-state lithium iron phosphate full battery assembled with the polymer electrolyte to which orotic acid is added is also improved. Orotic acid is abundant in source, low in price, and has high economic benefits. The preparation process of the polymer solid electrolyte containing orotic acid of the present invention is mature, low in cost, and adopts a casting method for film formation, which is simple to prepare and suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The graph is a cycle performance diagram of lithium-lithium batteries assembled with polymer solid electrolytes with orotic acid content of 7% and without orotic acid content of Comparative Example 1 and Example 1 of the present invention.

[0028] Figure 2 The figures are battery cycle performance diagrams at different current densities for lithium-lithium batteries assembled with polymer solid electrolytes containing orotic acid at 7% content in Comparative Example 1 and Example 1 of the present invention.

[0029] Figure 3 The figures are the ionic conductivity graphs of polymer solid electrolytes with different contents of orotic acid added to Comparative Example 1 and Example 1, Example 2, Example 3, Example 4, Example 5, Example 6, and Example 7 of the present invention at different temperatures, and the figures are the ionic conductivity graphs of polymer solid electrolytes with 7% orotic acid added to Comparative Example 1 and Example 1 at different temperatures.

[0030] Figure 4 1 is a graph of ion migration coefficients of polymer solid electrolytes with orotic acid content of 7% added in Comparative Example 1 and Example 1 of the present invention.

[0031] Figure 5 The impedance curves of the polymer solid electrolyte with orotic acid content of 7% and without orotic acid content of Comparative Example 1 and Example 1 of the present invention after different cycles are shown.

[0032] Figure 6 These are scanning electron microscope (SEM) images of the surfaces of lithium-lithium batteries assembled with polymer solid electrolytes with and without the addition of 7% orotic acid in Comparative Example 1 and Example 1 of the present invention after cycling, with (a, b) showing the lithium metal surface and (c, d) showing the electrolyte surface.

[0033] Figure 7 1 is an LSV test graph of the polymer solid electrolyte with orotic acid content of 7% and without orotic acid content of Comparative Example 1 and Example 1 of the present invention.

[0034] Figure 8 It is a cycle performance diagram of lithium iron phosphate full battery assembled with polymer solid electrolyte with orotic acid content of 7% in Comparative Example 1 and Example 1 of the present invention.

[0035] Figure 9 The infrared spectra of lithium-lithium batteries assembled with polymer solid electrolytes containing orotic acid at 7% and without containing orotic acid in Comparative Example 1 and Example 1 of the present invention after different cycles are shown.

[0036] Figure 10 These are XPS spectra of the lithium metal surface of lithium-lithium batteries assembled with polymer solid electrolytes containing 7% orotic acid (Comparative Example 1 and Example 1) after cycling. (a, b) show the lithium surface using the PEO-LiTFSI electrolyte, and (c, d) show the lithium surface using the PEO-LiTFSI-7% OA electrolyte.

[0037] Figure 11 This is a cycle performance diagram of lithium-lithium batteries assembled with polymer solid electrolytes containing different amounts of orotic acid added to Comparative Example 1 and Examples 1, 2, 3, 4, 5, 6, and 7 of the present invention. DETAILED DESCRIPTION

[0038] The technical solution of the present invention is further described below with reference to specific embodiments and in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited thereto.

[0039] Comparative Example 1

[0040] In a glove box (under a high-purity argon inert atmosphere), 0.44g of polyethylene oxide (PEO) (molecular weight 600,000) and 0.1435g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) were weighed into a glass anaerobic bottle. 15ml of N,N-dimethylformamide (DMF) was added and magnetically stirred at 60°C for 24 hours to form a homogeneous solution. The solution was then evenly dispersed and poured into a polytetrafluoroethylene mold. The mold was allowed to stand at room temperature for 3 hours. After some solvent evaporated, the mold was heated at 60°C for 24 hours for pre-drying. The solvent was then completely dried in a vacuum oven at 80°C for 12 hours, resulting in a 100μm solid polymer electrolyte membrane. Finally, the membrane was sliced ​​into 19mm circular pieces for later use.

[0041] The electrolyte film material prepared in Comparative Example 1 was used as a solid electrolyte and assembled into a Li / electrolyte / Li battery (i.e., a lithium-on-lithium symmetrical battery was assembled, and the assembly order was from bottom to top, with the positive electrode shell, lithium sheet, solid electrolyte, lithium sheet, gasket, spring sheet, and negative electrode shell being placed in sequence. The negative electrode shell specification was CR2032, the positive electrode shell specification was CR2032, the spring sheet specification was 15.4*1.1 mm, the gasket specification was φ16.2*1.0 mm, and the lithium sheet specification was φ12 mm).

[0042] Example 1

[0043] In a glove box, 0.44g of polyethylene oxide (PEO), 0.1435g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and 0.04392g of orotic acid (7wt%) were weighed into a glass anaerobic bottle. 15ml of N,N-dimethylformamide (DMF) was added and magnetically stirred at 60°C for 24 hours to form a homogeneous solution. The solution was then evenly dispersed and poured into a polytetrafluoroethylene mold. The mold was allowed to stand at room temperature for 3 hours. After some of the solvent evaporated, it was pre-dried by heating at 60°C for 24 hours. The solvent was then completely dried in a vacuum oven at 80°C for 12 hours. A 100μm solid polymer electrolyte membrane containing orotic acid was obtained. Finally, a 19mm circular electrolyte membrane was sliced ​​and prepared for use.

[0044] In order to test the relevant properties of the solid polymer electrolyte membrane prepared in the present invention, the following tests were performed on Example 1 and Comparative Example 1:

[0045] The electrolyte film material prepared in Example 1 was used as a solid electrolyte and assembled into a Li / electrolyte / Li battery (prepared in the same manner as in Comparative Example 1).

[0046] 1) In order to test the stabilizing effect of the solid polymer electrolyte membrane containing orotic acid on the interface, a lithium-lithium battery was tested. Figure 1 At 50°C, 0.1 mA cm -2 At a current density of 0.1 mAh cm -2 The charge-discharge test was conducted at a constant capacity. The figure shows that the electrolyte with orotic acid added allows the lithium-lithium battery to cycle stably for 2000 hours with a polarization voltage of approximately 100mV. In contrast, the electrolyte without orotic acid only cycles for 200 hours with a polarization voltage of approximately 180mV. This demonstrates that electrolytes containing orotic acid can both extend the life of lithium-lithium batteries and reduce polarization voltage, significantly improving electrochemical performance.

[0047] 2) Using different current densities (0.1 mA cm) -2 , 0.2 mA cm -2 , 0.3 mA cm -2 , test lithium-lithium batteries, from Figure 2It can be seen that with the addition of orotic acid electrolyte, the polarization voltage of lithium-lithium batteries is significantly reduced.

[0048] 3) In order to test the ionic conductivity of the electrolyte to which orotic acid was added, the solid polymer electrolyte membranes of Comparative Example 1 and each embodiment were used as polymer electrolytes to assemble stainless steel / polymer electrolyte / stainless steel batteries (the battery assembly sequence was from bottom to top, with the positive electrode shell, gasket, solid electrolyte, gasket, shrapnel, and negative electrode shell placed in sequence. The negative electrode shell specification was CR2032, the positive electrode shell specification was CR2032, the shrapnel specification was 15.4*1.1mm, the gasket specification was φ16.2*1.0mm, and the lithium sheet was φ12mm). The impedance of the battery was tested using the AC impedance method. The test was performed every 10°C in a temperature range of 30-80°C. Figure 3 As shown in the figure, the ionic conductivity of the PEO-LiTFSI electrolyte at 50 °C is 1.14×10 -5 S cm -1 The conductivity of the electrolyte after adding 3%, 5%, 7%, 9%, and 11% orotic acid was 4.31×10 -5 S cm -1 , 6.27×10 -5 S cm -1 , 3.78×10 -5 S cm -1 , 8.37×10 -5 S cm -1 , 9.66×10 -5 S cm -1 It can be seen that the electrolyte ion conductivity is improved by adding orotic acid.

[0049] 4) Test the ion migration number of lithium-lithium batteries, from Figure 4 It can be seen that the electrolyte ion migration number is improved by adding orotic acid. After adding 7% orotic acid, the ion migration number of the polymer electrolyte is increased from 0.23 to 0.33.

[0050] 5) Figure 5 The impedance of lithium-lithium batteries after different cycle times was tested. The tested batteries were placed at 50°C and the current density was 0.1 mA cm -1 , the charge and discharge capacity is 0.1 mAh cm -1 .

[0051] To judge the failure mechanism of Li / PEO interface, this test tracks the impedance of 20,50,80,100 circles of the circulation of Li-Li battery cycle, when using PEO-LiTFSI electrolyte (comparative example 1), overall along with the increase of cycle number, Rct constantly increases, and after 20,50,80,100 charge-discharge cycles, Rct is respectively 203,208,233,211Ω, illustrating that Li / PEO interface is constantly deteriorating in the circulation process. And when orotic acid is used for modifying polymer electrolyte, it can be seen that overall along with the increase of circulation, the Rct of battery declines, and before circulation, Rct is 195Ω, and after 20,50,80,100 charge-discharge cycles, Rct is respectively 168,174,150,163Ω, illustrating that the presence of orotic acid can make the Li / PEO interface of battery in the process of circulation tend to be stable.

[0052] 6) After 10 cycles, the lithium-lithium battery was disassembled and the morphology of the metal lithium sheet and the polymer surface was observed using a field emission scanning electron microscope. Planar SEM image of the lithium-lithium battery after 10 cycles, Figure 6 (a, b) are lithium surfaces, (c, d) are electrolyte surfaces, Figure 6 In (a), it can be seen that the surface of lithium metal is not flat, showing a rough lithium surface with many lithium particles and dendrites. Figure 6 (c) It can be seen that the electrolyte surface has been fragmented, with cracks and some small particles. It can be seen that when the PEO-LiTFSI in comparative example 1 is used as the electrolyte, the lithium metal and electrolyte interface react after the battery cycle and begin to deteriorate, eventually causing the electrolyte to break, which can easily lead to a short circuit in the battery application process. However, the composite electrolyte modified with PEO-LiTFSI-7% OA orotic acid in example 1 is very smooth and flat, both the electrolyte surface and the lithium surface ( Figure 6 (b, d)), it can be seen that lithium is uniformly deposited, which inhibits the growth of lithium dendrites, which shows that the presence of orotic acid has a positive effect on stabilizing the Li / PEO interface, and further verifies that the cycle life of lithium-lithium batteries with electrolytes containing orotic acid is increased.

[0053] 7) In order to test the stability of the polymer electrolyte to high voltage, the electrolyte membranes of Comparative Example 1 and Example 1 were used to assemble stainless steel / polymer electrolyte layer / lithium negative electrode batteries for testing (the battery assembly sequence was from bottom to top, with the positive electrode shell, gasket, solid electrolyte, lithium sheet, gasket, spring, and negative electrode shell being placed in order. The negative electrode shell specification was CR2032, the positive electrode shell specification was CR2032, the spring specification was 15.4*1.1mm, the gasket specification was φ16.2*1.0mm, and the lithium sheet was φ12mm). The test temperature was 50°C. Figure 7It can be seen that the addition of orotic acid does not reduce the electrochemical window of the polymer electrolyte.

[0054] 8) Weigh LiFPO4:PEO+LiTFSI:Super P=7:2:1 (mass ratio), where EO:Li in PEO+LiTFSI=20:1 (molar ratio), mix and dissolve in anhydrous acetonitrile solvent, stir on a stirring table to obtain a uniform slurry, use a scraper to evenly load the slurry on a carbon-coated aluminum foil, heat and dry in a vacuum constant temperature oven at 60°C, and roll and compact the positive electrode sheet, cut into the required size, weigh the mass of each sheet, and record it. Use lithium iron phosphate as the positive electrode active material, the electrolyte membrane of Example 1 or Comparative Example 1 as the electrolyte, and the lithium sheet as the negative electrode material to assemble a lithium iron phosphate / electrolyte / lithium full battery, and test its electrochemical performance. Figure 8 As shown in the figure, the solid-state full battery was tested at 50°C and 0.2C rate, and the discharge capacity of the electrolyte without orotic acid was 120 mAh g -1 , while the electrolyte with orotic acid added has a discharge capacity of 132 mAh g -1 Obviously, the full battery discharge capacity of the electrolyte with the addition of whey acid has been improved to a certain extent.

[0055] 9) Figure 9 The infrared spectra of the electrolytes of lithium-on-lithium batteries assembled with PEO-LiTFSI electrolyte and lithium-on-lithium batteries assembled with PEO-LiTFSI-7% OA electrolyte after different number of cycles were tested. From the figure, it can be found that the infrared peaks of the electrolytes did not change with orotic acid added and after different cycles, indicating that the added orotic acid does not exist in the form of organic matter after decomposition.

[0056] 10) Figure 10 Lithium-to-lithium batteries assembled with PEO-LiTFSI electrolyte and lithium-to-lithium batteries assembled with PEO-LiTFSI-7% OA electrolyte were cycled 10 times respectively. The XPS spectra of the lithium metal surface after disassembly are as follows: (a, b) are the lithium surface before and after cycling of the battery without adding orotic acid electrolyte, and (c, d) are the lithium surface before and after cycling of the battery with adding orotic acid electrolyte. The peak of LiN3 appeared on the Li surface after cycling, which shows that orotic acid reacted and decomposed with metal Li during the battery cycle to generate LiN3. The presence of LiN3 is beneficial to improving the battery cycle life and increasing the stability of the interface.

[0057] Example 2

[0058] In a glove box, 0.44g of polyethylene oxide (PEO), 0.1435g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and 0.00589g of orotic acid (1wt%) were weighed into a glass anaerobic bottle. 15ml of N,N-dimethylformamide (DMF) was added and magnetically stirred at 60°C for 24 hours to form a homogeneous solution. The solution was then evenly dispersed and poured into a polytetrafluoroethylene mold. The mold was allowed to stand at room temperature for 3 hours. After some of the solvent evaporated, it was pre-dried by heating at 60°C for 24 hours. The solvent was then completely dried in a vacuum oven at 80°C for 12 hours, resulting in a 100μm solid polymer electrolyte membrane containing orotic acid. Finally, the membrane was sliced ​​into 19mm circular films for later use.

[0059] The electrolyte film material prepared in this example was used as a solid electrolyte and assembled into a Li / electrolyte / Li battery.

[0060] Example 3

[0061] In a glove box, 0.44g of polyethylene oxide (PEO), 0.1435g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and 0.01805g of orotic acid (3wt%) were weighed into a glass anaerobic bottle. 15ml of N,N-dimethylformamide (DMF) was added and magnetically stirred at 60°C for 24 hours to form a homogeneous solution. The solution was then evenly dispersed and poured into a polytetrafluoroethylene mold. The mold was allowed to stand at room temperature for 3 hours. After some of the solvent evaporated, it was pre-dried by heating at 60°C for 24 hours. The solvent was then completely dried in a vacuum oven at 80°C for 12 hours, resulting in a 100μm solid polymer electrolyte membrane containing orotic acid. Finally, the membrane was sliced ​​into 19mm circular pieces for later use.

[0062] The electrolyte film material prepared in this example was used as a solid electrolyte and assembled into a Li / electrolyte / Li battery.

[0063] Example 4

[0064] In a glove box, 0.44g of polyethylene oxide (PEO), 0.1435g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and 0.03071g of orotic acid (5wt%) were weighed into a glass anaerobic bottle. 15ml of N,N-dimethylformamide (DMF) was added and magnetically stirred at 60°C for 24 hours to form a homogeneous solution. The solution was then evenly dispersed and poured into a polytetrafluoroethylene mold. The mold was allowed to stand at room temperature for 3 hours. After some of the solvent evaporated, it was pre-dried by heating at 60°C for 24 hours. The solvent was then completely dried in a vacuum oven at 80°C for 12 hours, resulting in a 100μm solid polymer electrolyte membrane containing orotic acid. Finally, the membrane was sliced ​​into 19mm circular pieces for later use.

[0065] The electrolyte film material prepared in this example was used as a solid electrolyte and assembled into a Li / electrolyte / Li battery.

[0066] Example 5

[0067] In a glove box, 0.44g of polyethylene oxide (PEO), 0.1435g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and 0.05771g of orotic acid (9wt%) were weighed into a glass anaerobic bottle. 15ml of N,N-dimethylformamide (DMF) was added and magnetically stirred at 60°C for 24 hours to form a homogeneous solution. The solution was then evenly dispersed and poured into a polytetrafluoroethylene mold. The mold was allowed to stand at room temperature for 3 hours. After some of the solvent evaporated, it was pre-dried by heating at 60°C for 24 hours. The solvent was then completely dried in a vacuum oven at 80°C for 12 hours, resulting in a 100μm solid polymer electrolyte membrane containing orotic acid. Finally, the membrane was sliced ​​into 19mm circular pieces for later use.

[0068] The electrolyte film material prepared in this example was used as a solid electrolyte and assembled into a Li / electrolyte / Li battery.

[0069] Example 6

[0070] In a glove box, 0.44g of polyethylene oxide (PEO), 0.1435g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and 0.07212g of orotic acid (11wt%) were weighed into a glass anaerobic bottle. 15ml of N,N-dimethylformamide (DMF) was added and magnetically stirred at 60°C for 24 hours to form a homogeneous solution. The solution was then evenly dispersed and poured into a polytetrafluoroethylene mold. The mold was allowed to stand at room temperature for 3 hours. After some of the solvent evaporated, it was pre-dried by heating at 60°C for 24 hours. The solvent was then completely dried in a vacuum oven at 80°C for 12 hours, resulting in a 100μm solid polymer electrolyte membrane containing orotic acid. Finally, the membrane was sliced ​​into 19mm circular pieces for later use.

[0071] The electrolyte film material prepared in this example was used as a solid electrolyte and assembled into a Li / electrolyte / Li battery.

[0072] Example 7

[0073] In a glove box, 0.44g of polyethylene oxide (PEO), 0.1435g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and 0.08719g of orotic acid (13wt%) were weighed into a glass anaerobic bottle. 15ml of N,N-dimethylformamide (DMF) was added and magnetically stirred at 60°C for 24 hours to form a homogeneous solution. The solution was then evenly dispersed and poured into a polytetrafluoroethylene mold. The mold was allowed to stand at room temperature for 3 hours. After some of the solvent evaporated, it was pre-dried by heating at 60°C for 24 hours. The solvent was then completely dried in a vacuum oven at 80°C for 12 hours, resulting in a 100μm solid polymer electrolyte membrane containing orotic acid. Finally, the membrane was sliced ​​into 19mm circular pieces for later use.

[0074] The lithium-lithium battery assembled with electrolytes containing different amounts of orotic acid was tested at 50 °C and 0.1 mA cm -2 At a current density of 0.1 mAh cm -2 Carry out charge and discharge test under the capacity. Figure 11 As shown, when the content of added orotic acid is 7wt%, the cycle life of the lithium-lithium battery is the longest, which can reach a life of 2000h.

[0075] Example 8

[0076] In a glove box, 0.44g of polyethylene oxide (PEO), 0.1435g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and 0.04392g of orotic acid (7wt%) were weighed into a glass anaerobic bottle. 15ml of N,N-dimethylformamide (DMF) was added and magnetically stirred at 60°C for 24 hours to form a homogeneous solution. The solution was then evenly dispersed and poured into a polytetrafluoroethylene mold. The mold was allowed to stand at room temperature for 5 hours, and after some solvent evaporated, it was pre-dried by heating at 40°C for 30 hours. The solvent was then completely dried in a vacuum oven at 80°C for 10 hours, resulting in a 100μm solid polymer electrolyte membrane containing orotic acid.

[0077] Example 9

[0078] In a glove box, 0.44g of polyethylene oxide (PEO), 0.1435g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and 0.04392g of orotic acid (7wt%) were weighed into a glass anaerobic bottle. 15ml of N,N-dimethylformamide (DMF) was added and magnetically stirred at 30°C for 24 hours to form a homogeneous solution. The solution was then evenly dispersed and poured into a polytetrafluoroethylene mold. The mold was allowed to stand at room temperature for 3 hours. After some solvent evaporated, the mold was pre-dried at 50°C for 20 hours and then placed in a vacuum oven at 80°C for 12 hours to completely dry the solvent, resulting in a 100μm solid polymer electrolyte membrane containing orotic acid.

[0079] Example 10

[0080] In a glove box, 0.44g of polyethylene oxide (PEO), 0.1435g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and 0.04392g of orotic acid (7wt%) were weighed into a glass anaerobic bottle. 15ml of N,N-dimethylformamide (DMF) was added and magnetically stirred at 30°C for 24 hours to form a homogeneous solution. The solution was then evenly dispersed and poured into a polytetrafluoroethylene mold. The mold was allowed to stand at room temperature for 3 hours. After some solvent evaporated, the mold was pre-dried at 60°C for 24 hours. The solvent was then completely dried in a vacuum oven at 60°C for 15 hours, resulting in a 100μm solid polymer electrolyte membrane containing orotic acid.

[0081] Example 11

[0082] In a glove box, 0.44g of polyethylene oxide (PEO), 0.1435g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and 0.04392g of orotic acid (7wt%) were weighed into a glass anaerobic bottle. 15ml of N,N-dimethylformamide (DMF) was added and magnetically stirred at 30°C for 24 hours to form a homogeneous solution. The solution was then evenly dispersed and poured into a polytetrafluoroethylene mold. The mold was allowed to stand at room temperature for 3 hours. After some solvent evaporated, the mold was pre-dried at 60°C for 24 hours and then placed in a vacuum oven at 70°C for 12 hours to completely dry the solvent, resulting in a 100μm solid polymer electrolyte membrane containing orotic acid.

[0083] Example 12

[0084] In a glove box, 0.44g of polyethylene oxide (PEO), 0.1914g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and 0.04752g of orotic acid (7wt%) were weighed into a glass anaerobic bottle. 15ml of N,N-dimethylformamide (DMF) was added and magnetically stirred at 30°C for 24 hours to form a homogeneous solution. The solution was then evenly dispersed and poured into a polytetrafluoroethylene mold. The mold was allowed to stand at room temperature for 3 hours. After some solvent evaporated, the mold was pre-dried at 60°C for 24 hours and then placed in a vacuum oven at 80°C for 12 hours to completely dry the solvent, resulting in a 100μm solid polymer electrolyte membrane containing orotic acid.

[0085] Example 13

[0086] In a glove box, 0.44g of polyethylene oxide (PEO), 0.1148g of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and 0.04176g of orotic acid (7wt%) were weighed into a glass anaerobic bottle. 15ml of N,N-dimethylformamide (DMF) was added and magnetically stirred at 30°C for 24 hours to form a homogeneous solution. The solution was then evenly dispersed and poured into a polytetrafluoroethylene mold. The mold was allowed to stand at room temperature for 3 hours. After some solvent evaporated, the mold was pre-dried at 60°C for 24 hours and then placed in a vacuum oven at 80°C for 12 hours to completely dry the solvent, resulting in a 100μm solid polymer electrolyte membrane containing orotic acid.

[0087] The above-described embodiments are only preferred solutions of the present invention and are not intended to limit the present invention in any form. Other variations and modifications are possible without exceeding the technical solutions described in the claims.

Claims

1. A solid polymer electrolyte membrane containing orotic acid, characterized in that: The solid polymer electrolyte membrane includes a polymer matrix, a conductive lithium salt and orotic acid; the polymer matrix is ​​polyethylene oxide, and the molecular weight of polyethylene oxide is 500,000-1.2 million; the mass of the orotic acid is 1-15% of the total mass of the polymer matrix, the conductive lithium salt and the orotic acid.

2. A solid polymer electrolyte membrane containing orotic acid according to claim 1, characterized in that: The ratio of the polyethylene oxide to the conductive lithium salt is (15-25):1 in terms of the molar ratio of EO (ethylene oxide):Li.

3. The solid polymer electrolyte membrane containing orotic acid according to claim 1, characterized in that: The conductive lithium salt is selected from one of LiTFSI, LiFSI, LiClO4, LiBOB, LiAsF6, and LiBF4.

4. A method for preparing a solid polymer electrolyte membrane containing orotic acid according to any one of claims 1 to 3, characterized in that: The steps include: (1) mixing a polymer matrix, a conductive lithium salt, orotic acid, and a solvent to form a casting solution; (2) The casting solution is poured into a mold and the solvent is removed by drying to obtain a solid polymer electrolyte membrane.

5. The method for preparing a solid polymer electrolyte membrane containing orotic acid according to claim 4, characterized in that: In the step (1), the solvent is N,N-dimethylformamide, and the mass ratio of the solvent to the polymer matrix is ​​(10-50):

1.

6. The method for preparing a solid polymer electrolyte membrane containing orotic acid according to claim 4, characterized in that: The stirring time after mixing in the step (1) is not less than 24 hours.

7. The method for preparing a solid polymer electrolyte membrane containing orotic acid according to claim 4, characterized in that: The drying in step (2) includes: standing at room temperature for 3-5 hours, heating at 30-60°C for 15-30 hours for pre-drying, and then placing in a vacuum oven at 80°C for drying.

8. Use of the solid polymer electrolyte membrane containing orotic acid according to any one of claims 1 to 3 in a lithium battery, characterized in that: The solid polymer electrolyte membrane serves as the electrolyte.

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