Polymer electrolytes, secondary batteries, and power consumption devices

Abstract

The present invention provides a polymer electrolyte, a secondary battery, and a power-consuming device that can achieve high energy density in batteries. [Solution] Embodiments of the present invention provide a polymer electrolyte comprising a polymer substrate and a copolymer. Here, the polymer substrate includes a support material, and the copolymer contains cyano groups, ester groups, and sulfonic acid groups. In the present invention, the polymer substrate provides mechanical strength as a support material, and the function of the copolymer is to form a stable interface with the positive and negative electrodes. Furthermore, since the copolymer contains cyano groups, ester groups, and sulfonic acid groups, all of which are polar groups, it can improve the mechanical performance of the electrolyte. At the same time, because it has high anti-reducing and antioxidant properties, it can form a stable SEI film with the negative electrode and a stable CEI with the positive electrode. Therefore, the fabricated secondary battery can have a high energy density and enable long-term cycles.

Description

Technical Field

[0001] The present invention relates to the field of batteries, and more particularly, to polymer electrolytes, secondary batteries, and power-consuming devices.

Background Art

[0002] In the field of new energy, the performance of batteries is becoming increasingly important. Compared with lithium-ion batteries (LIBs), lithium-metal batteries (LMBs) based on liquid electrolytes have a higher energy density, but there are serious safety concerns regarding internal short circuits caused by lithium dendrite growth. LMBs based on solid electrolytes have high energy density and high safety, but there are problems such as low ionic conductivity and poor interfacial contact. Gel polymer electrolytes have attracted wide attention because of their high safety, low interfacial resistance between the solid electrolyte and the electrode, and compatibility with the "roll-to-roll" LMB manufacturing process. At the same time, lithium-rich manganese-based cathodes (LRMO) have advantages such as high capacity, high voltage, and low cost, and are considered very promising for fabricating batteries with ultra-high energy density in combination with lithium metal. However, due to the poor interfacial performance between LRMO and the electrolyte, the practical application is hindered, and thus it is necessary to develop a new type of polymer electrolyte.

[0003] As can be seen from this, the prior art has the following disadvantages. Lithium-ion batteries have a low energy density, so it is necessary to combine lithium metal with lithium-rich manganese-based cathodes. However, since there are safety concerns in liquid batteries, the practical application is limited by the interfacial performance between the inorganic electrolyte and the electrode, and there is no compatibility with the current manufacturing process. Therefore, it is necessary to urgently develop a corresponding polymer electrolyte.

Summary of the Invention

Problems to be Solved by the Invention

[0004] This invention achieves high energy density in batteries by simultaneously combining lithium metal and lithium-rich manganese-based batteries through the structural design of polymer electrolytes. [Means for solving the problem]

[0005] Some embodiments of the present invention provide a polymer electrolyte comprising a polymer substrate and a copolymer. Here, the polymer substrate comprises a support material, and the copolymer contains cyano groups, ester groups, and sulfonic acid groups. In the present invention, the polymer substrate (A) provides mechanical strength as a support material, and the function of copolymer (B) is to form a stable interface with the positive and negative electrodes. As can be seen from this, copolymer (B) is formed by copolymerization of three types of monomers, each containing a cyano group, an ester group, and a sulfonic acid group, all of which are polar groups, and can therefore improve the mechanical performance of the electrolyte. At the same time, because it has high anti-reducing and antioxidant properties, it can form a stable SEI film (solid electrolyte interface film) with the negative electrode and a stable CEI (cathode electrolyte interface film) with the positive electrode. Since a lithium metal negative electrode and a lithium-rich manganese positive electrode can be combined simultaneously, the fabricated secondary battery can have a high energy density and enable long-term cycles.

[0006] In some embodiments, the weight ratio of the polymer substrate to the copolymer is in the range of 10:90 to 90:10, and selectively, the weight ratio is 30:70. When within this range, the polymer substrate (A) can provide sufficient mechanical performance, and the copolymer (B) can be stable at either the positive or negative electrode interface and provide additional kinetics, which is advantageous for capacity reallocation.

[0007] In some embodiments, the copolymer is formed by copolymerization of acrylonitrile (AN), lithium p-styrene sulfonate (LiSS), and vinylene carbonate (VC). The molar ratio of the monomers of acrylonitrile (AN), lithium p-styrene sulfonate (LiSS), and vinylene carbonate (VC) is 5-25:50-90:5-25, and selectively, the molar ratio of the monomers of acrylonitrile (AN) to vinylene carbonate (VC) is equal. Selectively, the molar ratio of the monomers of acrylonitrile (AN), lithium p-styrene sulfonate (LiSS), and vinylene carbonate (VC) is 20:60:20. In the present invention, acrylonitrile (AN) has polar functional groups and therefore has high voltage resistance stability. Since vinylene carbonate (VC) is stable with respect to lithium metal, it can form a stable SEI. Lithium p-styrene sulfonate (LiSS) can further improve the rate characteristics of batteries because it has an additional lithium ion source and can provide additional kinetics.

[0008] In some embodiments, the polymer substrate is selected from one or more of the following: polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), PVDF-HFP-PTFE (fluoropolymer), polyimide (PI), and polymethyl methacrylate (PMMA).

[0009] Some other embodiments of the present invention provide a secondary battery characterized by comprising a positive electrode sheet, a negative electrode sheet, and an electrolyte layer, wherein the electrolyte layer comprises the polymer electrolyte described above.

[0010] Further embodiments of the present invention provide a power consumption device characterized by including the secondary battery described above. [Effects of the Invention]

[0011] By designing the polymer electrolyte structure, lithium metal and LRMO can be combined by using a support material with a different polymer substrate and a copolymer formed by copolymerization of different monomers, and by adjusting the composition and ratio. This enables an energy density of 500 Wh / kg and long-term stable cycles of 500 cycles. [Modes for carrying out the invention]

[0012] The present invention allows for the inclusion of two types of polymers through the structural design of the polymer electrolyte, specifically comprising a polymer substrate (A) and a copolymer (B). The polymer substrate (A) contains a support material, and the copolymer (B) contains cyano groups, ester groups, and sulfonic acid groups. In the present invention, the polymer substrate (A) provides mechanical strength as a support material, and the function of copolymer (B) is to form a stable interface between the positive and negative electrodes. As can be seen from this, copolymer (B) is formed by copolymerization of three types of monomers, each containing a cyano group, an ester group, and a sulfonic acid group, all of which are polar groups, and can improve the mechanical performance of the electrolyte. At the same time, because it has high anti-reducing and antioxidant properties, it can form a stable SEI film (solid electrolyte interface film) with the negative electrode and a stable CEI (cathode electrolyte interface film) with the positive electrode. Since a lithium metal negative electrode and a lithium-rich manganese positive electrode can be combined simultaneously, the fabricated secondary battery has a high energy density, can reach 500 Wh / kg, and enables long-term cycles.

[0013] In some embodiments, the weight ratio of the polymer substrate (A) to the copolymer (B) is in the range of 10:90 to 90:10, and selectively 30:70. Within this range, the polymer substrate (A) can provide sufficient mechanical performance, and the copolymer (B) can be stable at either the positive or negative electrode interface and provide additional kinetics, which is advantageous for capacity reallocation.

[0014] In some embodiments, the polymer substrate (A) is a commercially available polymer and includes fluoropolymers such as polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), PVDF-HFP-PTFE (fluororubber), and non-fluoropolymers such as polyimide (PI) and polymethyl methacrylate (PMMA), but the present invention is not limited to these.

[0015] In some embodiments, the copolymer is formed by copolymerization of acrylonitrile (AN), lithium p-styrene sulfonate (LiSS), and vinylene carbonate (VC). Here, the polymerization method may be radical polymerization, and includes simple radical polymerization, atom transfer radical polymerization, reversible addition-cleavage chain transfer polymerization, etc. In the present invention, acrylonitrile (AN) has polar functional groups and therefore has high voltage resistance stability. Since vinylene carbonate (VC) is stable with respect to lithium metal, it can form a stable SEI. Since lithium p-styrene sulfonate (LiSS) has an additional lithium ion source and can provide additional kinetics, the rate characteristics of the battery can be further improved.

[0016] Specifically, the molar ratio of acrylonitrile (AN), lithium p-styrene sulfonate (LiSS), and vinylene carbonate (VC) monomers is 5-25:50-90:5-25, and selectively 20:60:20. When within this range, it is possible to ensure that the ionic conductivity of the entire electrolyte layer is relatively high, and that the battery's cycle performance and capacity are relatively good. In this invention, the molar ratio of acrylonitrile (AN) and vinylene carbonate (VC) monomers is equal. In this situation, a stable interface can be formed for both the positive and negative electrodes, thereby improving the stability of the battery.

[0017] Furthermore, some embodiments of the present invention provide a method for producing the above-mentioned polymer electrolyte, comprising the following steps.

[0018] The polymer substrate (A) is a commercially available polymer and includes fluoropolymers such as polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), PVDF-HFP-PTFE (fluororubber), and non-fluoropolymers such as polyimide (PI) and polymethyl methacrylate (PMMA), but the present invention is not limited to these.

[0019] Method for synthesizing copolymer (B): Acrylonitrile (AN), lithium p-styrene sulfonate (LiSS), and vinylene carbonate (VC) are mixed and dissolved in a certain amount of solvent (e.g., dimethyl sulfoxide). Then, 0.1 wt% azobisisobutyronitrile (AIBN) is dissolved in the mixture. The resulting solution is held at 60°C for 15 hours under an argon atmosphere. The resulting solid is dissolved in anhydrous dimethyl sulfoxide and washed with toluene to remove residual monomers and initiators to obtain a pure copolymer. The molar ratios of AN, LiSS, and VC monomers are 5-25:50-90:5-25, selectively equal in molar ratios of AN and VC monomers, and selectively 20:60:20. In some embodiments, the solvent described above may include polar solvents such as dimethyl sulfoxide (DMSO) and N,N-dimethylformamide. In some specific embodiments, DMSO may be used as the solvent, and the mass fraction of this polymer solution may be 10%.

[0020] Polymer preparation: A polymer substrate (A) and copolymer (B) are mixed in a solvent (DMSO), thoroughly heated and stirred to dissolve, and then the solution is poured into a mold and dried to obtain a polymer film. Alternatively, the polymer substrate (A) is electrospinned, and the copolymer (B) solution is poured onto the polymer substrate (A) and dried to form a film and obtain a polymer film. Here, the weight ratio of polymer substrate (A) to copolymer (B) is 10:90 to 90:10, and selectively 30:70.

[0021] Preparation of polymer electrolyte: The polymer film obtained above is immersed in a high-voltage electrolyte for 24 hours. Here, the electrolyte includes several commonly used high-voltage electrolytes (4.5V or higher), but the present invention is not limited to these.

[0022] In the embodiments described above, the high-voltage resistant electrolyte includes 14% lithium hexafluorophosphate (LiPF6), 1% lithium bis(fluorosulfonyl)imide (LiFSI), 0.8% lithium difluorophosphate (LiPO2F2), 0.1% lithium tetrafluoroborate (LiBF4), 0.1% vinylene carbonate (VC), 1% 1,3-propanesultone (1,3-PS), 24.9% ethylene carbonate (EC), 41.5% ethylmethyl carbonate (EMC), and 16.6% diethyl carbonate (DEC), but the present invention is not limited to these.

[0023] Some embodiments of the present invention further provide a secondary battery and a power-consuming device including the secondary battery. The secondary battery comprises a positive electrode sheet, a negative electrode sheet, and an electrolyte layer.

[0024] Method for manufacturing a positive electrode sheet: A positive electrode active material, a positive electrode conductive agent, and a positive electrode binder are dispersed in a solvent at a weight ratio of 95:2:3 to form a uniform positive electrode slurry. The positive electrode slurry is applied to the surface of the positive electrode current collector, and after undergoing processes such as drying and cold pressing, a positive electrode active material layer is formed on the positive electrode current collector to obtain a positive electrode sheet. Since the ratio between each component in the positive electrode slurry can be set by referring to the conventional ratio, it is not limited here. The positive electrode conductive agent is selected from one of carbon black, acetylene black, graphene, carbon nanotubes, carbon nanofibers, etc., or a combination of two or more kinds mixed in any ratio. The positive electrode binder is selected from one of PVDF and its derivatives. The positive electrode active material can include one or more of lithium cobalt oxide (LCO), lithium nickel oxide (LNO), lithium manganese oxide (LMO), lithium nickel manganese oxide (LNMO), lithium nickel cobalt manganese oxide (NCM), lithium nickel cobalt aluminum oxide (NCA), and lithium-rich manganese-based oxide (LRMO). In some embodiments, the positive electrode current collector may be an aluminum foil.

[0025] Negative electrode sheet Selected from lithium metals of different thicknesses (for example, lithium metals with a thickness of 10 μm to 600 μm).

[0026] Electrolyte layer The above-mentioned polymer electrolyte is directly used as the polymer electrolyte layer.

[0027] Secondary battery The positive electrode sheet, the electrolyte layer, and the negative electrode sheet are sequentially placed into a mold and assembled. After assembly, pressure is applied, and the nut at the top of the support is tightened at a constant pressure to obtain a secondary battery. Note: The assembly process is completed in a glove box under an argon atmosphere, and the particle diameters of the corresponding powders of the positive electrode sheet, the electrolyte layer, and the negative electrode sheet all maintain consistency.

[0028] It should be noted that while the battery produced by the method described above is a lithium-ion secondary battery, the battery produced by the present invention may be a sodium-ion secondary battery or a potassium-ion secondary battery.

[0029] Engineers in this field will understand that the battery manufacturing method described above is merely an embodiment. Other methods commonly used in the art may be employed, provided that they do not depart from the content disclosed in this invention.

[0030] The reagents and raw materials used in this invention are all commercially available.

[0031] The present invention does not require any special method for assembling the battery described above; any assembly method familiar to engineers in the art may be used. Furthermore, the above-described technical solution can be applied not only to commonly used all-solid-state lithium-ion batteries, but also to various kinetic batteries such as all-solid-state sodium-ion batteries and all-solid-state potassium-ion batteries. The above-described secondary battery can be applied to any suitable power-consuming device, including electric vehicles, but is not limited to electric vehicles.

[0032] The present invention will be further described below with reference to several specific examples and comparative examples. [Examples]

[0033] Example 1 (1) Preparation of polymer electrolytes The polymer substrate (A) is polyvinylidene fluoride (PVDF). Method for synthesizing copolymer (B): Acrylonitrile (AN), lithium p-styrene sulfonate (LiSS), and vinylene carbonate (VC) are mixed and dissolved in a solvent (DMSO can be used as the solvent, and the mass fraction of the polymer solution may be 10%). Then, 0.1 wt% azobisisobutyronitrile (AIBN) is dissolved in the mixture. The resulting solution is held at 60°C for 15 hours under an argon atmosphere. The resulting solid is dissolved in anhydrous dimethyl sulfoxide and washed with toluene to remove residual monomers and initiators to obtain a pure copolymer. Here, the molar ratio of monomers AN, LiSS, and VC is 20:60:20. A polymer substrate (A) and a copolymer (B) are mixed in a solvent, thoroughly heated and stirred to dissolve them, and then the solution is poured into a polytetrafluoroethylene mold and dried to obtain a polymer film. Here, the weight ratio of polymer substrate (A) to copolymer (B) is 30:70. The polymer film obtained above is immersed for 24 hours in a high-voltage electrolyte commonly used in this field to obtain a polymer electrolyte.

[0034] (2) Positive electrode sheet The positive electrode active material is selected from lithium-rich manganese oxide (LRMO), the positive electrode conductive agent is selected from carbon black, the positive electrode binder is selected from PVDF, and the positive electrode current collector is selected from aluminum foil.

[0035] (3) Negative electrode sheet Select from 10 μm lithium metals.

[0036] (4) Electrolyte layer The polymer electrolyte described above is used directly as the polymer electrolyte layer.

[0037] (5) Secondary battery The positive electrode sheet, electrolyte layer, and negative electrode sheet are assembled by sequentially placing them into a mold. After assembly, the assembly is pressurized to 100 MPa, and the nuts at the top of the vertical columns are tightened under constant pressure to obtain a secondary battery. Note: The assembly process is completed in a glove box under an argon atmosphere, ensuring that the particle diameters of the corresponding powders in the positive electrode sheet, electrolyte layer, and negative electrode sheet are all consistent.

[0038] Example 2 The preparation method is the same as in Example 1, but the difference is that the weight ratio of the polymer substrate (A) to the copolymer (B) in Example 2 is 10:90.

[0039] Example 3 The preparation method is the same as in Example 1, but the difference is that the weight ratio of polymer substrate (A) to copolymer (B) in Example 3 is 90:10.

[0040] Example 4 The preparation method is the same as in Example 1, but the difference is that the weight ratio of the polymer substrate (A) to the copolymer (B) in Example 4 is 50:50.

[0041] Example 5 The preparation method is the same as in Example 1, but the difference is that the weight ratio of polymer substrate (A) to copolymer (B) in Example 5 is 60:40.

[0042] Example 6 The preparation method is the same as in Example 1, but the difference is that the molar ratio of AN, LiSS, and VC monomers in copolymer (B) in Example 6 is 5:90:5.

[0043] Example 7 The preparation method is the same as in Example 1, but the difference is that the molar ratio of AN, LiSS, and VC monomers in copolymer (B) in Example 7 is 25:50:25.

[0044] Example 8 The preparation method is the same as in Example 1, but the difference is that the molar ratio of AN, LiSS, and VC monomers in copolymer (B) in Example 8 is 10:80:10.

[0045] Example 9 The preparation method is the same as in Example 1, but the difference is that the molar ratio of AN, LiSS, and VC monomers in copolymer (B) in Example 9 is 15:70:15.

[0046] Example 10 The preparation method is the same as in Example 1, but the difference is that the molar ratio of AN, LiSS, and VC monomers in copolymer (B) in Example 10 is 20:60:20.

[0047] Example 11 The preparation method is the same as in Example 1, but the difference is that the molar ratio of AN, LiSS, and VC monomers in copolymer (B) in Example 11 is 20:65:15.

[0048] Example 12 The preparation method is the same as in Example 1, but the difference is that the polymer substrate (A) in Example 12 is PVDF-HFP.

[0049] Example 13 The preparation method is the same as in Example 1, but the difference is that the polymer substrate (A) in Example 13 is PVDF-HFP-PTFE.

[0050] Example 14 The preparation method is the same as in Example 1, but the difference is that the polymer substrate (A) in Example 14 is polyimide (PI).

[0051] Example 15 The preparation method is the same as in Example 1, but the difference is that the polymer substrate (A) in Example 15 is polymethyl methacrylate (PMMA).

[0052] Example 16 The preparation method is the same as in Example 1, but the difference is that the polymer substrate (A) in Example 16 is a mixture of polyvinylidene fluoride (PVDF) and polyimide (PI) (weight ratio is 1:1).

[0053] Comparative Example 1 The preparation method is the same as in Example 1, but the difference is that the weight ratio of polymer substrate (A) to copolymer (B) in Comparative Example 1 is 5:95.

[0054] Comparative Example 2 The preparation method is the same as in Example 1, but the difference is that the weight ratio of polymer substrate (A) to copolymer (B) in Comparative Example 2 is 95:5.

[0055] Comparative Example 3 The preparation method is the same as in Example 1, but the difference is that Comparative Example 3 contains only the polymer substrate (A) and does not contain the copolymer (B).

[0056] Comparative Example 4 The preparation method is the same as in Example 1, but the difference is that Comparative Example 4 contains only the copolymer (B) and does not contain the polymer substrate (A).

[0057] Comparative Example 5 The preparation method is the same as in Example 1, but the difference is that the molar ratio of AN, LiSS, and VC monomers in copolymer (B) in Comparative Example 5 is 3:94:3.

[0058] Comparative Example 6 The preparation method is the same as in Example 1, but the difference is that the molar ratio of AN, LiSS, and VC monomers in copolymer (B) in Comparative Example 6 is 30:40:30.

[0059] Comparative Example 7 The preparation method is the same as in Example 1, but the difference is that the molar ratio of AN, LiSS, and VC monomers in copolymer (B) in Comparative Example 7 is 0:75:25.

[0060] Comparative Example 8 The preparation method is the same as in Example 1, but the difference is that the molar ratio of AN, LiSS, and VC monomers in copolymer (B) in Comparative Example 8 is 25:75:0.

[0061] Comparative Example 9 The preparation method is the same as in Example 1, but the difference is that the molar ratio of AN, LiSS, and VC monomers in copolymer (B) in Comparative Example 9 is 50:0:50.

[0062] Comparative Example 10 The preparation method is the same as in Example 1, but the difference is that the molar ratio of AN, LiSS, and VC monomers in copolymer (B) in Comparative Example 10 is 0:0:100.

[0063] Comparative Example 11 The preparation method is the same as in Example 1, but the difference is that the molar ratio of AN, LiSS, and VC monomers in copolymer (B) in Comparative Example 11 is 0:100:0.

[0064] Comparative Example 12 The preparation method is the same as in Example 1, but the difference is that the molar ratio of AN, LiSS, and VC monomers in copolymer (B) in Comparative Example 12 is 100:0:0.

[0065] Performance test methods Under conditions of 25°C, the secondary batteries obtained in Examples 1-16 and Comparative Examples 1-12 were subjected to long-cycle charge-discharge after being brought to a fixed volume, and the number of cycles at room temperature was measured. The test conditions were to perform a long-cycle charge-discharge test after bringing the battery to a fixed volume, and during the process, the initial fixed-volume discharge ratio capacity and the number of cycles at room temperature when the SOH was 50% were recorded. The operating voltage range was 1.9-3.7V, the fixed-volume multiplier was 0.1C, and the room-temperature cycle test multiplier was 0.3C. For Example 4, the test method was the same as for the other examples and comparative examples, but the difference was that the operating voltage range was 1.4-4.25V. Note: The following conditions being met simultaneously are considered examples of good performance. Li / Li symmetrical battery: 1 mA / cm² 2 The short-circuit cycle time for the battery is greater than 500 hours, and for LMR / Li batteries, the number of room-temperature cycles at 80% SOH is greater than 300, and the 1C capacity is greater than 170 mAh / g. The test results are shown in Table 1 below.

[0066] [Table 1]

[0067] As can be seen from Examples 1 to 16 described above, the present invention can contain two types of polymers through the structural design of the polymer electrolyte, specifically comprising a polymer substrate (A) and a copolymer (B). The polymer substrate (A) contains a support material and provides mechanical support, and the copolymer (B) contains cyano groups, ester groups, and sulfonic acid groups. In the present invention, the polymer substrate (A) provides mechanical strength as a support material, and the function of copolymer (B) is to form a stable interface with the positive and negative electrodes. As can be seen from the above, copolymer (B) is formed by copolymerization of three types of monomers, each containing a cyano group, an ester group, and a sulfonic acid group, all of which are polar groups, and can therefore improve the mechanical performance of the electrolyte. At the same time, because it has high anti-reducing and antioxidant properties, it can form a stable SEI film (solid electrolyte interface film) with the negative electrode and a stable CEI (cathode electrolyte interface film) with the positive electrode. Since a lithium metal negative electrode and a lithium-rich manganese positive electrode can be combined simultaneously, the fabricated secondary battery can have a high energy density and enable long-term cycles. Furthermore, copolymer (B) is formed by copolymerization of acrylonitrile (AN), lithium p-styrene sulfonate (LiSS), and vinylene carbonate (VC), and these three copolymers each possess different functions. Acrylonitrile (AN) has a polar functional group, the cyano group, and therefore has high voltage resistance stability. Vinylene carbonate (VC) is stable with respect to lithium metal, and can therefore form a stable SEI. Lithium p-styrene sulfonate (LiSS) has an additional lithium ion source, thereby improving the battery's capacity and rate characteristics.

[0068] To explain in more detail, as can be seen by comparing Examples 1-5 and Comparative Examples 1-4, when the weight ratio of polymer substrate (A) to copolymer (B) is in the range of 10:90 to 90:10, and selectively 30:70, the polymer substrate (A) can provide mechanical strength as a support material, and the copolymer (B) forms a stable interface with the positive and negative electrodes, so the fabricated secondary battery has relatively good performance, high energy density, and enables long cycles. Specifically, as can be seen from Example 1, 30% polymer substrate (A) is sufficient to provide mechanical performance, AN and VC in 70% copolymer (B) are stable with respect to both the positive and negative electrode interfaces, and the contained LiSS provides additional kinetics, which is advantageous for capacity expression. As can be seen from Example 2, as the copolymer (B) content increases, the ionic conductivity of the entire electrolyte layer becomes very high, so the corresponding secondary battery can have a very high 1C capacity, reaching 193 mAh / g. As can be seen from Examples 3 to 5, the polymer substrate (A) is relatively abundant, resulting in very good overall mechanical performance, and the corresponding secondary batteries exhibit relatively good cycle stability. As can be seen from Comparative Examples 1 and 4, the polymer substrate (A) is excessively scarce, resulting in very poor mechanical performance, and the corresponding secondary batteries exhibit poor long-term cycle stability. As can be seen from Comparative Examples 2 and 3, the copolymer (B) is excessively scarce, resulting in poor interfacial stability between the positive and negative electrodes and low conductivity, and the resulting secondary batteries exhibit poor long-term cycle stability and low capacity.

[0069] As can be seen by comparing Examples 6-11 and Comparative Examples 5-12, the molar ratios of acrylonitrile (AN), lithium p-styrene sulfonate (LiSS), and vinylene carbonate (VC) monomers in copolymer (B) are 5-25:50-90:5-25, selectively 20:60:20, and selectively equal in molar ratios of acrylonitrile (AN) and vinylene carbonate (VC) monomers. When within this range, the ionic conductivity is high and the capacity is high, resulting in a secondary battery with excellent cycle stability and capacity. Specifically, as can be seen from Examples 6 and 8, when lithium p-styrene sulfonate (LiSS) is relatively abundant in copolymer (B), the ionic conductivity is high, and the corresponding secondary battery has a relatively high capacity, reaching 195 mAh / g. As can be seen from Examples 7 and 9-10, the corresponding secondary battery exhibits relatively good cycle stability because the copolymer (B) contains a relatively large amount of acrylonitrile (AN) and vinylene carbonate (VC). As can be seen from Example 11, when the molar ratio of acrylonitrile (AN) and vinylene carbonate (VC) monomers is not equal, the corresponding secondary battery shows some improvement in performance, but the improvement is limited. This is because the unequal molar ratio of acrylonitrile (AN) and vinylene carbonate (VC) affects the balance between the stability of the positive and negative electrodes of the corresponding secondary battery, and can further affect the performance of the secondary battery. As can be seen from Comparative Example 5, when the amount of AN and VC in copolymer (B) is excessively low, the interfacial stability between the positive and negative electrodes is relatively poor, resulting in relatively poor long-term cycle stability for the corresponding secondary battery. As can be seen from Comparative Example 6, when the amount of LiSS in copolymer (B) is excessively low, the interfacial stability between the positive and negative electrodes is relatively poor, resulting in poor long-term cycle stability for the secondary battery. As can be seen from Comparative Example 7, when copolymer (B) does not contain AN, the interfacial stability with the positive electrode is very poor, resulting in relatively poor long-term cycle stability of the secondary battery. As can be seen from Comparative Example 8, when copolymer (B) does not contain VC, the interfacial stability with the negative electrode is very poor, resulting in relatively poor long-term cycle stability of the secondary battery.As can be seen from Comparative Example 9, when copolymer (B) does not contain LiSS, the conductivity is low, and therefore the secondary battery has a relatively low capacity. As can be seen from Comparative Example 10, when copolymer (B) does not contain AN and LiSS, the interfacial stability with the positive electrode is relatively poor, and the conductivity is also relatively low, resulting in poor long-term cycle stability and a relatively low capacity for the secondary battery. As can be seen from Comparative Example 11, when copolymer (B) does not contain AN and VC, the interfacial stability with both the positive and negative electrodes is relatively poor, resulting in relatively poor long-term cycle stability for the secondary battery. As can be seen from Comparative Example 12, when copolymer (B) does not contain LiSS and VC, the interfacial stability with the negative electrode is relatively poor, and the conductivity is also relatively low, resulting in poor long-term cycle stability and a relatively low capacity for the secondary battery.

[0070] As can be seen from Examples 12 to 16, the polymer substrate (A) can be selected from one or more of the following: polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), PVDF-HFP-PTFE (fluororubber), polyimide (PI), and polymethyl methacrylate (PMMA). As a result, the secondary batteries formed have relatively good cycle stability and capacity. Furthermore, PVDF-HFP and PVDF have similar performance, and the secondary batteries formed from them have relatively superior cycle stability and capacity. [Industrial applicability]

[0071] As described above, the present invention, through the structural design of the polymer electrolyte, enables the combination of lithium metal and LRMO by using a support material which is a different polymer substrate and a copolymer formed by copolymerization of different monomers, and by adjusting the composition and ratio, thereby achieving an energy density of 500 Wh / kg and a long-term stable cycle of 500 cycles.

[0072] The above outlines some features of embodiments so that those skilled in the art may better understand aspects of the present invention. Those skilled in the art should understand that the present invention can be readily used on the basis of designing or modifying other processes and structures to accomplish the same objectives and / or achieve the same advantages as the embodiments presented herein. Those skilled in the art should also be aware that such equivalent structures do not depart from the spirit and scope of the present invention, and that various changes, substitutions, and modifications can be made herein in circumstances that do not depart from the spirit and scope of the present invention.

Claims

1. Polymer substrate and Copolymer and A polymer electrolyte comprising a polymer substrate comprising a support material, wherein the copolymer contains a cyano group, an ester group, and a sulfonic acid group.

2. The polymer electrolyte according to claim 1, wherein the weight ratio of the polymer substrate to the copolymer is in the range of 10:90 to 90:

10.

3. The polymer electrolyte according to claim 1, wherein the weight ratio of the polymer substrate to the copolymer is 30:

70.

4. The polymer electrolyte according to claim 1, wherein the copolymer is formed by copolymerization of acrylonitrile (AN), lithium p-styrene sulfonate (LiSS), and vinylene carbonate (VC).

5. The polymer electrolyte according to claim 4, wherein the molar ratio of the monomers of acrylonitrile (AN), lithium p-styrene sulfonate (LiSS), and vinylene carbonate (VC) is 5 to 25:50 to 90:5 to 25.

6. The polymer electrolyte according to claim 5, wherein the molar ratio of the acrylonitrile (AN) monomer and the vinylene carbonate (VC) monomer are equal.

7. The polymer electrolyte according to claim 5, wherein the molar ratio of the monomers of acrylonitrile (AN), lithium p-styrene sulfonate (LiSS), and vinylene carbonate (VC) is 20:60:

20.

8. The polymer electrolyte according to claim 1, wherein the polymer substrate is selected from one or more of the following: polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), PVDF-HFP-PTFE (fluororubber), polyimide (PI), and polymethyl methacrylate (PMMA).

9. A secondary battery comprising a positive electrode sheet, a negative electrode sheet, and an electrolyte layer, wherein the electrolyte layer comprises a polymer electrolyte according to any one of claims 1 to 8.

10. A power consumption device including a secondary battery as described in claim 9.

Images