Molecular sieve-polymer membrane, composite electrolyte, lithium ion secondary battery, preparation method, and application

Abstract

The present invention discloses a molecular sieve-polymer film, a composite electrolyte, a lithium ion secondary battery, a preparation method, and an application. The molecular sieve-polymer film comprises a mesoporous molecular sieve and a non-polar polymer, and the mass ratio of the mesoporous molecular sieve to the molecular sieve-polymer film is (0.1-0.5):1; the mesoporous molecular sieve comprises one or more of ZSM-5, SBA-15, and MCM-41; the non-polar polymer is incompatible with an organic solvent. The present invention adopts a mesoporous molecular sieve and a non-polar polymer as a matrix, and an electrolyte in which a cyclic carbonate can be used as a solvent, so that lithium ions can only move through the pores in the mesoporous molecular sieve, thereby suppressing the growth of lithium dendrites in a lithium battery during a long cycle, thereby improving the safety of the lithium battery; on the basis of improving safety, excellent electrochemical performance can also be guaranteed.

Description

Technical Field

[0001] The present invention relates to the field of lithium battery solid electrolytes, and in particular to a molecular sieve-polymer membrane, a composite electrolyte, a lithium ion secondary battery, a preparation method and an application. Background Art

[0002] Lithium battery is a new type of green energy with high conversion efficiency, high energy density, long cycle life and zero memory effect. Its application in mobile phones, computers and cars has greatly facilitated people's daily life and has become an indispensable part of people's lives.

[0003] However, with the large-scale use of lithium batteries, there are more and more lithium battery safety accidents. Reports of battery spontaneous combustion and explosion, resulting in loss of life and property, are common. Moreover, as the scale of battery use expands, people's requirements for the energy density of the battery itself are getting higher and higher. As the energy density of lithium batteries increases, the harm and losses caused by safety accidents in the battery also increase.

[0004] There are currently two main solutions to this problem. The first strategy is to use lithium iron phosphate to replace the ternary cathode material. However, the lower energy density of lithium iron phosphate means that this strategy will limit the improvement of battery energy density. The second is to use safe electrolytes instead of commercial electrolytes. This strategy avoids the problem of limited energy density improvement because there is no need to replace electrode materials. However, the performance of most safe electrolyte batteries is inferior to that of commercial electrolytes. This strategy will affect the battery cycle life.

[0005] Therefore, how to improve battery safety while reducing the impact on battery performance is a technical problem that needs to be urgently solved in this field. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the defect in the prior art that the safety of lithium batteries is improved while the battery performance is reduced, and a molecular sieve-polymer composite electrolyte, a lithium ion secondary battery and its preparation method and application are provided. The present invention adopts a mesoporous molecular sieve and a non-polar polymer as a matrix and an electrolyte with a cyclic carbonate as a solvent, so that lithium ions can only move through the pores in the mesoporous molecular sieve, thereby inhibiting the growth of lithium dendrites in the lithium battery during a long cycle, thereby improving the safety of the lithium battery.

[0007] After much creative work, the inventors found that the current composite electrolyte technology basically uses a method of directly mixing electrolyte with polymer or oxide electrolyte. Although this method can avoid the presence of a large amount of liquid, due to the low ionic conductivity of the polymer, it will cause uneven deposition of lithium ions in long-term charge and discharge cycles, thereby forming lithium dendrites. When lithium dendrites pierce the electrolyte membrane or break, they may still cause internal short circuits in the battery, leading to accidents.

[0008] In the present invention, a molecular sieve-polymer composite electrolyte is prepared by mixing a mesoporous molecular sieve with a non-polar polymer that is incompatible with an organic solvent (such as a cyclic carbonate solvent), and then adding an organic electrolyte with the cyclic carbonate as a solvent. Due to the incompatibility of the organic solvent (such as the cyclic carbonate) and the non-polar polymer, the electrolyte only exists in the pores of the mesoporous molecular sieve, so that the lithium ions are only carried in the pores of the molecular sieve, thereby achieving the inhibition of the growth of lithium dendrites. The composite electrolyte is applied to lithium batteries, which can effectively improve the safety of lithium batteries in long-term cycles.

[0009] The present invention provides a molecular sieve-polymer membrane, which comprises a mesoporous molecular sieve and a non-polar polymer, wherein the mass ratio of the mesoporous molecular sieve to the molecular sieve-polymer membrane is (0.1-0.5):1;

[0010] The mesoporous molecular sieve includes one or more of ZSM-5, SBA-15 and MCM-41;

[0011] The non-polar polymer and the organic solvent are incompatible.

[0012] In the present invention, preferably, the mass ratio of the mesoporous molecular sieve to the molecular sieve-polymer membrane is (0.2-0.5):1, for example (0.3-0.4):1, for example 0.3:1 or 0.4:1.

[0013] During the research and development process, the inventors found that if the mass ratio of the mesoporous molecular sieve and the molecular sieve-polymer membrane is less than 0.1:1, it is not conducive to the movement of lithium ions in the pores of the mesoporous molecular sieve, resulting in a decrease in battery performance; if the mass ratio of the mesoporous molecular sieve and the molecular sieve-polymer membrane is greater than 0.5:1, it is not conducive to the dispersion of the molecular sieve in the polymer, resulting in a decrease in battery performance.

[0014] In the present invention, the mass ratio of the mesoporous molecular sieve to the non-polar polymer may be (0.1-0.7):1, such as 3:7, 4:6 or 1:9.

[0015] In the present invention, preferably, the mesoporous molecular sieve is ZSM-5, SBA-15 or MCM-41, such as ZSM-5 or SBA-15.

[0016] In the present invention, the mesoporous molecular sieve may also be referred to as a mesoporous material. According to the provisions of the International Union of Pure and Applied Chemistry (IUPAC), a mesoporous material generally refers to a type of porous material with a pore size between 2-50 nm.

[0017] In the present invention, the ZSM-5 generally refers to a zeolite molecular sieve containing organic amine cations.

[0018] The chemical composition of ZSM-5 can be expressed as the molar ratio of oxides: 0.9±0.2M 2 / n O:Al 2 O 3 :(5-100)SiO 2 :ZH 2 O, wherein M is a cation (such as an alkali metal sodium ion and an organic amine ion); n is the valence of the cation; and Z is from 0 to 40.

[0019] In the present invention, in the ZSM-5, the silicon-aluminum ratio may be (50-100):1.

[0020] In the present invention, the SBA-15 generally has a two-dimensional hexagonal through-hole structure and has a P6mm space group. The silicon dioxide on the SBA-15 skeleton is generally amorphous, and no obvious diffraction peak is observed in wide-angle XRD diffraction.

[0021] In the present invention, the MCM-41 is a long-range ordered mesoporous material with uniform pore size, and has the characteristics of extremely high BET specific surface area, large adsorption capacity, uniform mesoporous structure, etc. Its pores are arranged in hexagonal order, uniform in size, and the pore size can be continuously adjusted in the range of 2-10nm.

[0022] In the present invention, the non-polar polymer generally refers to a polymer with a symmetrical structure and a total dipole moment equal to zero.

[0023] In the present invention, the non-polar polymer and the organic solvent are incompatible, which means that the non-polar polymer will not dissolve in the organic solvent.

[0024] In the present invention, preferably, the non-polar polymer is polyethylene and / or polypropylene, such as polyethylene or polypropylene.

[0025] The polyethylene may be conventional polyethylene in the art, such as polyethylene with a weight average molecular weight of 50,000 to 500,000, or polyethylene with a weight average molecular weight of 150,000.

[0026] The polypropylene may be conventional polypropylene in the art, such as polypropylene with a weight average molecular weight of 100,000 to 800,000, or polypropylene with a weight average molecular weight of 300,000.

[0027] In the present invention, preferably, the mesoporous molecular sieve is ZSM-5, and the non-polar polymer is polyethylene.

[0028] In the present invention, preferably, the mesoporous molecular sieve is ZSM-5, the non-polar polymer is polyethylene, and the mass ratio of the mesoporous molecular sieve to the molecular sieve-polymer membrane is (0.1-0.3):1, such as 0.1:1 or 0.3:1.

[0029] In the present invention, preferably, the mesoporous molecular sieve is ZSM-5, the non-polar polymer is polyethylene, and the mass ratio of the mesoporous molecular sieve to the non-polar polymer is (0.1-0.5):1, such as 1:9 or 3:7.

[0030] In the present invention, preferably, the mesoporous molecular sieve is SBA-15, and the non-polar polymer is polypropylene.

[0031] In the present invention, preferably, the mesoporous molecular sieve is SBA-15, the non-polar polymer is polypropylene, and the mass ratio of the mesoporous molecular sieve to the molecular sieve-polymer membrane is (0.2-0.5):1, for example 0.4:1.

[0032] In the present invention, preferably, the mesoporous molecular sieve is SBA-15, the non-polar polymer is polypropylene, and the mass ratio of the mesoporous molecular sieve to the non-polar polymer is (0.5-0.7):1, for example, 4:6.

[0033] In the present invention, the organic solvent may be a cyclic carbonate solvent.

[0034] The cyclic carbonate solvent may include, but is not limited to, one or a combination of ethylene carbonate, propylene carbonate, and γ-butyrolactone, such as ethylene carbonate and / or propylene carbonate.

[0035] The present invention also provides a method for preparing the molecular sieve-polymer membrane, which comprises the following steps: mixing the mesoporous molecular sieve and the liquid non-polar polymer to obtain a mixture A, and forming the mixture A into a membrane.

[0036] Wherein, when the non-polar polymer is polyethylene and / or polypropylene, the liquid non-polar polymer can be obtained by heating to 180-220° C. (eg, 180-200° C., and for example, 200° C.).

[0037] The film formation can be performed by forming a film through a mold, for example, the mixture A is cooled and formed into a film in a polytetrafluoroethylene mold.

[0038] The present invention also provides a molecular sieve-polymer composite electrolyte, which comprises the molecular sieve-polymer membrane and a lithium salt solution.

[0039] In the present invention, the lithium salt solution may contain a lithium salt and an organic solvent A.

[0040] Wherein, preferably, the lithium salt is LiY; wherein Y - Including but not limited to: PF 6 - , CH 3 SO 3 - 、SCN - , BF 4 - , ClO 4 - 、NO 3 - , AsF 6 - 、AlCl 4 - ,(CF 3 SO 2 ) 2 N - 、(FSO 2 ) 2 N - CF 3 SO 3 - , B(OC 2 O 2 ) 2 - or TFSI - .

[0041] Wherein, the lithium salt may be LiPF 6 or LiTFSI (lithium bis(trifluoromethanesulfonyl)imide).

[0042] Wherein, the organic solvent A may be a cyclic carbonate solvent.

[0043] Preferably, the cyclic carbonate solvent includes, but is not limited to, one or a combination of ethylene carbonate, propylene carbonate, and γ-butyrolactone, such as ethylene carbonate and / or propylene carbonate.

[0044] Wherein, in the lithium salt solution, the concentration of the lithium salt may be 0.5-1.5 mol / L, for example, 1.0 mol / L or 1.1 mol / L.

[0045] The present invention also provides a method for preparing a molecular sieve-polymer composite electrolyte, which comprises the following steps: mixing the molecular sieve-polymer membrane and the lithium salt solution to obtain a mixture B.

[0046] The mixing method may be: dropping the lithium salt solution onto the molecular sieve-polymer membrane; or soaking the molecular sieve-polymer membrane in the lithium salt solution, for example, for 30 minutes.

[0047] After the mixing, the mixture B can be left to stand in an argon atmosphere for 5 minutes.

[0048] The present invention also provides an application of the molecular sieve-polymer composite electrolyte as an electrolyte in a lithium ion secondary battery.

[0049] The present invention also provides a lithium ion secondary battery, which comprises the molecular sieve-polymer composite electrolyte.

[0050] Wherein, the lithium-ion secondary battery may include a positive electrode sheet, the molecular sieve-polymer composite electrolyte, and a metal lithium sheet in sequence.

[0051] On the basis of being in accordance with the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0052] The reagents and raw materials used in the present invention are commercially available.

[0053] The positive and progressive effects of the present invention are:

[0054] The present invention effectively inhibits the growth of lithium dendrites formed in the long-term cycle of lithium batteries by constructing an electrolyte that can only transmit lithium ions through the pores of mesoporous molecular sieves, avoids battery safety accidents caused by battery short circuits caused by lithium dendrites piercing the diaphragm or breaking, and effectively improves the safety of lithium batteries. In addition, the electrolyte in the present invention can ensure excellent electrochemical performance, good battery cycle performance, and long cycle life on the basis of effectively improving the safety of lithium batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 This is a SEM image of the lithium metal surface of the lithium battery in Example 1 after 80 cycles.

[0056] Figure 2 This is a test result diagram of the symmetrical lithium battery in Example 1 after continuous charge and discharge for 4500 minutes. DETAILED DESCRIPTION

[0057] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0058] Example 1

[0059] 1. Electrolyte preparation and battery assembly

[0060] (1) 7 g of polyethylene (weight average molecular weight 50,000-500,000, specifically polyethylene with a weight average molecular weight of 150,000) was heated to 200° C., 3 g of ZSM-5 (in ZSM-5, the silicon-aluminum ratio is (50-100):1) was added thereto, stirred evenly, poured into a polytetrafluoroethylene mold and cooled, to obtain a molecular sieve-polymer membrane;

[0061] (2) LiPF 6 Mixed with ethylene carbonate to form LiPF 6 An electrolyte solution with a concentration of 1.0 mol / L;

[0062] (3) soaking the molecular sieve-polymer membrane in step (1) in the electrolyte solution in step (2) for 30 minutes;

[0063] (4) placing the immersed membrane in an argon atmosphere for 5 minutes to obtain a molecular sieve-polymer composite electrolyte;

[0064] (5) Assemble a lithium battery containing a molecular sieve-polymer composite electrolyte in the order of lithium iron phosphate positive electrode sheet, molecular sieve-polymer composite electrolyte, and lithium sheet, using CR2016 as the outer shell. The battery is used for cycle performance testing;

[0065] (6) A symmetrical lithium battery containing a molecular sieve-polymer composite electrolyte was assembled in the order of lithium sheet, molecular sieve-polymer composite electrolyte, and lithium sheet, using CR2016 as the outer shell. The battery was used for symmetrical lithium testing.

[0066] 2. Test results:

[0067] (1) Cyclic performance: At room temperature, the charge and discharge cycle was carried out at a current rate of 0.2C. The initial capacity was 152 mAh / g, and the capacity retention rate after 80 cycles was 97%. The surface of the metal lithium sheet after the cycle was dense and smooth (such as Figure 1 shown);

[0068] (2) Symmetrical lithium battery test: at room temperature, at 0.5 mA / cm 2 The current density is used for continuous charge and discharge cycles (charge and discharge are 60 minutes each), and the polarization voltage of the symmetrical lithium battery is <0.6V within 4500 minutes of continuous charge and discharge (such as Figure 2 shown).

[0069] Example 2

[0070] 1. Electrolyte preparation and battery assembly

[0071] (1) 6 g of polypropylene (weight average molecular weight 100,000-800,000, specifically polypropylene with a weight average molecular weight of 300,000) was heated to 200° C., 4 g of SBA-15 was added thereto, stirred evenly, poured into a polytetrafluoroethylene mold and cooled to obtain a molecular sieve-polymer membrane;

[0072] (2) mixing LiTFSI and propylene carbonate to prepare an electrolyte solution with a LiTFSI concentration of 1.1 mol / L;

[0073] (3) soaking the molecular sieve-polymer membrane in step (1) in the electrolyte solution in step (2) for 30 minutes;

[0074] (4) placing the immersed membrane in an argon atmosphere for 5 minutes to obtain a molecular sieve-polymer composite electrolyte;

[0075] (5) Assemble a lithium battery containing a molecular sieve-polymer composite electrolyte in the order of lithium iron phosphate positive electrode sheet, molecular sieve-polymer composite electrolyte, and lithium sheet, using CR2016 as the outer shell. The battery is used for cycle performance testing;

[0076] (6) A symmetrical lithium battery containing a molecular sieve-polymer composite electrolyte was assembled in the order of lithium sheet, molecular sieve-polymer composite electrolyte, and lithium sheet, using CR2016 as the outer shell. The battery was used for symmetrical lithium testing.

[0077] 2. Test results:

[0078] (1) Cyclic performance: At room temperature, the charge and discharge cycle was carried out at a current rate of 0.2C. The initial capacity was 150 mAh / g, and the capacity retention rate after 60 cycles was 96%;

[0079] (2) Symmetrical lithium battery test: at room temperature, at 0.5 mA / cm 2 The symmetrical lithium battery was subjected to continuous charge and discharge cycles (charge and discharge were 60 min each), and the polarization voltage was <0.5 V within 2000 min of continuous charge and discharge.

[0080] Example 3

[0081] The amount of ZSM-5 in Example 1 was reduced to 1 g, the amount of polyethylene was increased to 9 g, and the other experimental conditions were the same as in Example 1.

[0082] The cycle performance is as follows: at room temperature, the charge and discharge cycle is carried out at a current rate of 0.2C, the initial capacity is 121mAh / g, and the capacity retention rate is 73% after 50 cycles. The surface of the metal lithium sheet after the cycle is dense and smooth.

[0083] Comparative Example 1

[0084] The amount of ZSM-5 in Example 1 was increased to 7 g, the amount of polyethylene was reduced to 3 g, and the other experimental conditions were the same as in Example 1.

[0085] Normal dispersion and film formation are not possible, and cycle data measurement is not possible.

[0086] Comparative Example 2

[0087] The ZSM-5 in Example 1 was replaced by Y-type zeolite molecular sieve (SiO 2 / Al 2 O 3 The other experimental conditions were the same as those in Example 1.

[0088] The cycle performance is as follows: at room temperature, the charge and discharge cycle is carried out at a current rate of 0.2C, the initial capacity is 73mAh / g, and the capacity retention rate is 65% after 50 cycles.

Claims

1. A molecular sieve-polymer composite electrolyte, characterized in that: It contains a molecular sieve-polymer membrane and a lithium salt solution; The molecular sieve-polymer membrane comprises a mesoporous molecular sieve and a non-polar polymer, and the mass ratio of the mesoporous molecular sieve to the molecular sieve-polymer membrane is (0.1-0.5):1; The mesoporous molecular sieve includes one or more of ZSM-5, SBA-15 and MCM-41; The non-polar polymer and the organic solvent are incompatible.

2. The molecular sieve-polymer composite electrolyte according to claim 1, characterized in that: The molecular sieve-polymer membrane satisfies one or more of the following conditions: ① The mass ratio of the mesoporous molecular sieve to the molecular sieve-polymer membrane is (0.2-0.5):1; ② The mass ratio of the mesoporous molecular sieve to the non-polar polymer is (0.1-0.7):1; ③ The mesoporous molecular sieve is ZSM-5, SBA-15 or MCM-41; ④ The non-polar polymer is polyethylene and / or polypropylene; and ⑤ The organic solvent is a cyclic carbonate solvent.

3. The molecular sieve-polymer composite electrolyte according to claim 2, characterized in that: The molecular sieve-polymer membrane satisfies one or more of the following conditions: ① The mass ratio of the mesoporous molecular sieve to the molecular sieve-polymer membrane is (0.3-0.4):1; ② The mass ratio of the mesoporous molecular sieve to the non-polar polymer is 3:7, 4:6 or 1:9; ③ The polyethylene is a polyethylene with a weight average molecular weight of 50,000 to 500,000; ④ The polypropylene is a polypropylene with a weight average molecular weight of 100,000 to 800,000; and ⑤ The cyclic carbonate solvent includes but is not limited to ethylene carbonate, propylene carbonate, γ-butyrolactone or a combination of several thereof.

4. The molecular sieve-polymer composite electrolyte according to claim 2, characterized in that: The molecular sieve-polymer membrane satisfies one or more of the following conditions: ① The mass ratio of the mesoporous molecular sieve to the molecular sieve-polymer membrane is 0.3:1 or 0.4:1; ② The polyethylene is a polyethylene with a weight average molecular weight of 150,000; ③ The polypropylene is a polypropylene with a weight average molecular weight of 300,000; and ④ The cyclic carbonate solvent is ethylene carbonate and / or propylene carbonate.

5. The molecular sieve-polymer composite electrolyte according to any one of claims 1 to 4, characterized in that: The mesoporous molecular sieve is ZSM-5, and the non-polar polymer is polyethylene.

6. The molecular sieve-polymer composite electrolyte according to claim 5, characterized in that: The mass ratio of the mesoporous molecular sieve to the molecular sieve-polymer membrane is (0.1-0.3):1; And / or, the mass ratio of the mesoporous molecular sieve to the non-polar polymer is (0.1-0.5):

1.

7. The molecular sieve-polymer composite electrolyte according to claim 5, characterized in that: The mass ratio of the mesoporous molecular sieve to the molecular sieve-polymer membrane is 0.1:1 or 0.3:1; And / or, the mass ratio of the mesoporous molecular sieve to the non-polar polymer is 1:9 or 3:

7.

8. The molecular sieve-polymer composite electrolyte according to any one of claims 1 to 4, characterized in that: The mesoporous molecular sieve is SBA-15, and the non-polar polymer is polypropylene.

9. The molecular sieve-polymer composite electrolyte according to claim 8, characterized in that: The mass ratio of the mesoporous molecular sieve to the molecular sieve-polymer membrane is (0.2-0.5):1; And / or, the mass ratio of the mesoporous molecular sieve to the non-polar polymer is (0.5-0.7):

1.

10. The molecular sieve-polymer composite electrolyte according to claim 8, characterized in that: The mass ratio of the mesoporous molecular sieve to the molecular sieve-polymer membrane is 0.4:1; And / or, the mass ratio of the mesoporous molecular sieve to the non-polar polymer is 4:

6.

11. The molecular sieve-polymer composite electrolyte according to claim 1, characterized in that: The lithium salt solution comprises a lithium salt and an organic solvent A.

12. The molecular sieve-polymer composite electrolyte according to claim 11, characterized in that: The lithium salt is LiY; wherein Y - Including but not limited to: PF6 - 、CH3SO3 - 、SCN - 、BF4 - 、ClO4 - 、NO3 - 、AsF6 - 、AlCl4 - 、(CF3SO2)2N - 、(FSO2)2N - CF3SO3 - 、B(OC2O2)2 - or TFSI - ; And / or, the organic solvent A is a cyclic carbonate solvent; And / or, in the lithium salt solution, the concentration of the lithium salt is 0.5-1.5 mol / L.

13. The molecular sieve-polymer composite electrolyte according to claim 12, characterized in that: The lithium salt is LiPF6 or LiTFSI; And / or, the cyclic carbonate solvent includes but is not limited to one or a combination of ethylene carbonate, propylene carbonate, and γ-butyrolactone; And / or, in the lithium salt solution, the concentration of the lithium salt is 1.0 mol / L or 1.1 mol / L.

14. The molecular sieve-polymer composite electrolyte according to claim 13, characterized in that: The cyclic carbonate solvent is ethylene carbonate and / or propylene carbonate.

15. A method for preparing a molecular sieve-polymer composite electrolyte, characterized in that: The method comprises the following steps: mixing the molecular sieve-polymer membrane according to any one of claims 1 to 10 and the lithium salt solution according to any one of claims 11 to 14 to obtain a mixture B.

16. The method for preparing a molecular sieve-polymer membrane according to claim 15, characterized in that: The mixing method is: dropping the lithium salt solution onto the molecular sieve-polymer membrane; or soaking the molecular sieve-polymer membrane in the lithium salt solution.

17. The method for preparing a molecular sieve-polymer membrane according to claim 15, characterized in that: The method for preparing the molecular sieve-polymer membrane comprises the following steps: The mesoporous molecular sieve and the liquid non-polar polymer are mixed to obtain a mixture A, and the mixture A is formed into a membrane.

18. The method for preparing a molecular sieve-polymer membrane according to claim 17, characterized in that: When the non-polar polymer is polyethylene and / or polypropylene, the liquid non-polar polymer is obtained by heating to 180-220°C.

19. The method for preparing a molecular sieve-polymer membrane according to claim 17, characterized in that: The film is formed by a mold.

20. The method for preparing a molecular sieve-polymer membrane according to claim 17, characterized in that: The film forming step is to cool the mixture A in a polytetrafluoroethylene mold and form a film.

21. Use of the molecular sieve-polymer composite electrolyte according to any one of claims 1 to 14 as an electrolyte in a lithium ion secondary battery.

22. A lithium ion secondary battery, characterized in that: It comprises the molecular sieve-polymer composite electrolyte as claimed in any one of claims 1 to 14.

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