Lithium-manganese battery

Abstract

The invention provides a lithium-manganese battery. The lithium-manganese battery comprises a positive pole piece, a negative pole piece, a diaphragm and an electrolyte, a positive active material of the positive pole piece comprises manganese dioxide, and the negative pole piece comprises a lithium metal negative pole; the diaphragm comprises a base membrane and a coating located on at least one side surface of the base membrane, and the coating comprises a polymer solid electrolyte and an inorganic solid electrolyte. The diaphragm in the lithium-manganese battery is subjected to functionalization treatment of the composite coating of the polymer solid electrolyte and the inorganic solid electrolyte, so that the liquid retention capacity of the diaphragm is improved, and the problem that the electrolyte consumption of the diaphragm is reduced due to positive electrode expansion in the discharge process is solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium ion batteries, and relates to a lithium-manganese battery. BACKGROUND

[0002] As a lithium primary battery (non-rechargeable), the lithium-manganese battery uses metal lithium as a negative electrode, manganese dioxide as a positive electrode, and a non-woven fabric separator to isolate the positive and negative electrodes. Compared with other lithium batteries, the lithium-manganese battery has relatively low material and manufacturing costs and good safety. Therefore, it is also the most widely used commercial lithium battery in the world.

[0003] For the lithium-manganese battery, during discharging, the electrolyte and the negative electrode are gradually consumed, and the positive electrode swells. This phenomenon determines that the current is unstable or even abnormal at the end of discharging, and the swelling of the positive electrode causes more electrolyte to be adsorbed to the positive electrode end and consumed by the positive electrode, resulting in a decrease in the content of electrolyte in the separator and a decrease in ion transmission capacity, which seriously affects the electrochemical performance of the lithium-manganese battery.

[0004] In the structure of the lithium-manganese battery, the separator is a crucial component. It physically separates the positive electrode (manganese dioxide and conductive agent, etc.) and the negative electrode (metal lithium) to prevent internal short circuiting, while allowing lithium ions to pass freely to form a current loop. An ideal separator should have good ion conductivity, electronic insulation, chemical stability, certain mechanical strength, and excellent electrolyte infiltration and retention capacity. The polyolefin-based separator or ceramic separator in the prior art cannot solve the problem caused by the swelling of the positive electrode during discharging.

[0005] Therefore, how to improve the liquid retention capacity of the separator in the lithium-manganese battery and avoid the influence of lithium ion transmission during discharging is a technical problem that needs to be solved urgently. SUMMARY

[0006] In view of the deficiencies in the prior art, the purpose of the present application is to provide a lithium-manganese battery. The separator in the lithium-manganese battery of the present application is subjected to functionalization treatment by a combination coating of a polymer solid electrolyte and an inorganic solid electrolyte, which increases the liquid retention capacity of the separator and avoids the problem of a decrease in the amount of electrolyte in the separator caused by the swelling of the positive electrode during discharging.

[0007] To achieve the purpose of the present application, the following technical solutions are adopted:

[0008] The present application provides a lithium-manganese battery, which comprises a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte.

[0009] The positive electrode active material of the positive electrode sheet comprises manganese dioxide, and the negative electrode sheet comprises a lithium metal negative electrode.

[0010] The diaphragm includes a base membrane and a coating located on at least one side of the surface of the base membrane, the coating including a polymer solid electrolyte and an inorganic solid electrolyte.

[0011] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0012] As a preferred technical solution of the present invention, the mass ratio of the polymer solid electrolyte to the inorganic solid electrolyte is (1~3):1.

[0013] As a preferred technical solution of the present invention, the inorganic solid electrolyte is dispersed in the polymer solid electrolyte.

[0014] As a preferred technical solution of the present invention, the polymer electrolyte comprises a polymer and a lithium salt.

[0015] As a preferred technical solution of the present invention, the polymer in the polymer solid electrolyte includes any one or a combination of at least two of polyoxyethylene (PEO), polyvinylidene fluoride (PVDF), PVDF copolymer or polyacrylonitrile (PAN), preferably PVDF and / or PVDF copolymer.

[0016] Preferably, the lithium salt comprises any one or a combination of at least two of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate, lithium difluorooxalate borate, lithium trifluoromethanesulfonate, lithium tetrafluoroborate, or lithium difluorophosphate, and is preferably lithium bis(fluorosulfonyl)imide and / or lithium trifluoromethanesulfonate.

[0017] As a preferred technical solution of the present invention, the inorganic solid electrolyte includes an oxide solid electrolyte, which includes any one or a combination of at least two of perovskite solid electrolyte, NASICON solid electrolyte or garnet solid electrolyte, preferably NASICON solid electrolyte.

[0018] As a preferred technical solution of the present invention, the thickness of the base film is 12μm~30μm, preferably 18μm~30μm.

[0019] As a preferred technical solution in this invention, the thickness of the coating is 2μm~4μm.

[0020] As a preferred technical solution of the present invention, the total porosity of the diaphragm is 38%~70%, and the pore size of the diaphragm is 10nm~100nm.

[0021] As a preferred technical solution of the present invention, the method for preparing the diaphragm includes:

[0022] The coating is laminated onto at least one side surface of the base film to obtain the diaphragm.

[0023] As a preferred technical solution of the present invention, the composite method includes a slurry coating method, wherein the slurry coating method includes:

[0024] A coating slurry is applied to at least one side of the base membrane and dried to obtain the separator. The coating slurry comprises a polymer solid electrolyte, an inorganic solid electrolyte, and a solvent.

[0025] As a preferred technical solution of the present invention, the solid content of the coating slurry is 10%~30%.

[0026] As a preferred technical solution of the present invention, the positive electrode sheet includes a positive current collector and a positive active material layer located on at least one side surface of the positive current collector.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] In the lithium-manganese battery of the present invention, a separator structure with a coating of a polymer solid electrolyte and an inorganic solid electrolyte mixture is adopted. On the one hand, the ionic conductivity and mechanical strength of the separator are improved. On the other hand, during the discharge process, as lithium ions are continuously inserted into the positive electrode to form lithium manganese oxide, the phase structure of the positive electrode changes, and the positive electrode expands along with the side reaction. The positive electrode's ability to absorb electrolyte also increases, causing the electrolyte to concentrate in the positive electrode and be consumed by the positive electrode. The separator structure of the present invention increases the electrolyte retention capacity of the separator, solving the problem of reduced electrolyte usage and deteriorated battery performance caused by positive electrode discharge expansion. Detailed Implementation

[0029] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0030] The "range" disclosed in this invention can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. This type of range definition can include or exclude endpoints; any endpoint can be independently included or excluded, and they can be arbitrarily combined, meaning any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for specific parameters, it is understood that ranges of 60~110 and 80~120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are also listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this invention, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0" and "5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, when a parameter is described as an integer selected from "2~10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0031] In this invention, "a combination of at least two" refers to a quantity greater than or equal to two, unless otherwise specified. For example, "any combination of one or at least two" means one or more or more items. It can be understood that when referring to "a combination of at least two," it refers to any suitable combination of multiple items, that is, a combination of "at least two" items carried out in a manner that does not conflict with and enables the implementation of this invention.

[0032] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0033] The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0034] Those skilled in the art will understand that the order in which the steps are written in the methods of the various embodiments does not imply a strict execution order. The detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, but are preferably performed sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), meaning that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0035] In this invention, open-ended technical features or solutions described using terms such as "comprising" do not exclude additional members beyond those listed unless otherwise specified. They can be considered as providing both closed-ended features or solutions comprised of the listed members and open-ended features or solutions that include additional members beyond the listed members. For example, A includes a1, a2, and a3. Unless otherwise specified, it may also include other members or exclude additional members. This can be considered as providing both technical features or solutions where "A is composed of a1, a2, and a3" or "A is selected from a1, a2, and a3," and technical features or solutions where "A includes not only a1, a2, and a3, but also other members."

[0036] In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" represents a group consisting of A, B, and "a combination of A and B". "Containing A and / or B" can mean "containing A, containing B, and containing A and B", or "containing A, containing B, or containing A and B", and can be appropriately understood according to the context.

[0037] In this invention, the terms "first aspect," "second aspect," "third aspect," "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," "fourth," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on the quantity.

[0038] In this invention, "optional" means that something is optional, that is, it refers to any one of the two parallel solutions of "having" or "not having". If there are multiple "optional" options in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, then each "optional" option is independent.

[0039] In this invention, "room temperature" generally refers to 4℃~35℃, and can refer to 20℃±5℃. In some embodiments of this invention, room temperature refers to 20℃~30℃.

[0040] In one embodiment, the present invention provides a lithium manganese battery, the lithium manganese battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte;

[0041] The positive electrode active material of the positive electrode includes manganese dioxide, and the negative electrode includes a lithium metal negative electrode.

[0042] The diaphragm includes a base membrane and a coating located on at least one side of the surface of the base membrane, the coating including a polymer solid electrolyte and an inorganic solid electrolyte.

[0043] In the lithium-manganese battery of the present invention, a separator structure with a coating of a polymer solid electrolyte and an inorganic solid electrolyte mixture is adopted. On the one hand, the ionic conductivity and mechanical strength of the separator are improved. On the other hand, during the discharge process, as lithium ions are continuously inserted into the positive electrode to form lithium manganese oxide, the phase structure of the positive electrode changes, and the positive electrode expands along with the side reaction. The positive electrode's ability to absorb electrolyte also increases, causing the electrolyte to concentrate in the positive electrode and be consumed by the positive electrode. The separator structure of the present invention increases the electrolyte retention capacity of the separator, solving the problem of reduced electrolyte usage and deteriorated battery performance caused by positive electrode discharge expansion.

[0044] The separator of the present invention solves the problem of electrolyte enrichment and expansion of the positive electrode caused by the presence of manganese dioxide positive electrode material in lithium manganese batteries. This can only be achieved by having both polymer solid electrolyte and inorganic solid electrolyte in the coating. The above problem cannot be solved if either of these substances is missing.

[0045] In some embodiments, the mass ratio of the polymer solid electrolyte to the inorganic solid electrolyte is (1~3):1, for example 1:1, 1.3:1, 1.5:1, 1.8:1, 2:1, 2.3:1, 2.5:1, 2.8:1 or 3:1, etc.

[0046] In this invention, a suitable mass ratio of polymer solid electrolyte to inorganic solid electrolyte helps to improve the ionic conductivity and mechanical strength of the diaphragm, while also better improving the liquid retention effect of the diaphragm; and preferably up to (1~3):1, the liquid retention effect of the diaphragm is further improved.

[0047] In some embodiments, the inorganic solid electrolyte is dispersed in the polymer solid electrolyte.

[0048] In some embodiments, the polymer electrolyte comprises a polymer and a lithium salt.

[0049] In some embodiments, the polymer in the polymer solid electrolyte includes any one or a combination of at least two of PEO, PVDF, PVDF copolymer, or PAN, preferably PVDF and / or PVDF copolymer.

[0050] Preferably, the lithium salt comprises any one or a combination of at least two of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate, lithium difluorooxalate borate, lithium trifluoromethanesulfonate, lithium tetrafluoroborate, or lithium difluorophosphate, and is preferably lithium bis(fluorosulfonyl)imide and / or lithium trifluoromethanesulfonate.

[0051] In some embodiments, the inorganic solid electrolyte includes an oxide solid electrolyte, which includes any one or a combination of at least two of perovskite solid electrolyte, NASICON solid electrolyte, or garnet solid electrolyte, preferably a NASICON solid electrolyte.

[0052] It is understood that this invention does not impose specific limitations on the type of substance in inorganic solid electrolytes; any substance that conforms to the corresponding characteristic structure is applicable to this invention.

[0053] For example, the perovskite-type solid electrolyte includes, but is not limited to, lithium lanthanum titanium oxide (Li). 3x La 2 / 3-x TiO3(LLTO, x>0); the NASICON-type solid electrolyte includes, but is not limited to, Li 1+a Al a Ti 2-a (PO4)3 (LATP, 0 < a < 2) and / or Li 1+b Al b Ge 2-b (PO4)3 (LAGP, 0 < b < 2), etc.; the garnet-type solid electrolyte includes, but is not limited to, Li7La3Zr2O 12 (LLZO) and its doped derivatives, wherein the doping element includes, but is not limited to, at least one of Ta, Ga, Al, Fe or Nb; the doped derivative can be Li 6.4 La3Zr 1.4 Ta 0.6 O 12 (Ta-LLZO), Li 6.4 La3Zr 1.4 Nb0.6 O 12 (Nb-LLZO) or Li 6.24 La3Zr2Al 0.24 O 12 (Al-LLZO), etc.

[0054] In this invention, the combination of polymer solid electrolytes of PVDF and / or PVDF copolymer systems with NASICON-type solid electrolytes is more conducive to improving the ionic conductivity of PVDF and its mechanical strength.

[0055] In some embodiments, the thickness of the base film is 12μm to 30μm, preferably 18μm to 30μm, such as 12μm, 15μm, 18μm, 20μm, 23μm, 25μm, 26μm, 27μm, 28μm, 29μm, 30μm, etc.

[0056] In some embodiments, the thickness of the coating is 2μm to 4μm, such as 2μm, 2.5μm, 3μm, 3.5μm or 4μm.

[0057] In the separator structure of lithium manganese batteries, the base film is thicker than that of other types of lithium-ion batteries. The base film with a thickness of 12μm to 30μm works synergistically with the coating with a thickness of 2μm to 4μm to improve the ionic conductivity of the separator and enhance its thermal stability.

[0058] In some embodiments, the total porosity of the diaphragm is 38% to 70%, for example 38%, 40%, 43%, 45%, 48%, 50%, 53%, 55%, 58%, 60%, 63%, 65%, 68%, or 70%.

[0059] In some embodiments, the pore size of the diaphragm is 10nm to 100nm, such as 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm or 100nm.

[0060] In some embodiments, the method for preparing the diaphragm includes:

[0061] The coating is laminated onto at least one side surface of the base film to obtain the diaphragm.

[0062] In some embodiments, the composite method includes a slurry coating method, which includes:

[0063] A coating slurry is applied to at least one side of the base membrane and dried to obtain the separator. The coating slurry comprises a polymer solid electrolyte, an inorganic solid electrolyte, and a solvent.

[0064] In the membrane preparation process, the present invention does not require the addition of a binder to the coating slurry. The polymer in the polymer solid electrolyte has polymer chains that can form weak interaction forces with the polymer chains in the base membrane, thus playing a bonding role and achieving a good bond between the base membrane and the coating.

[0065] Furthermore, it is understood that the solvents used in this invention are all conventionally selected, and substances that are volatile and easy to disperse are acceptable, including but not limited to tetrahydrofuran or dimethyl ether (DME).

[0066] In some embodiments, the solid content of the coating slurry is 10% to 30%, for example, 10%, 15%, 20%, 25% or 30%.

[0067] In some embodiments, the positive electrode includes a positive current collector and a layer of positive active material located on at least one side of the surface of the positive current collector.

[0068] It should be noted that, apart from the above-mentioned feature limitations, the preparation process of the raw materials and structure of the lithium manganese battery in this invention, as well as the battery preparation process, are all conventional technical solutions. Without violating the technical concept of this invention, the relevant technical contents of conventional lithium manganese batteries are applicable to this invention.

[0069] Example 1

[0070] This embodiment provides a lithium manganese battery, which includes a positive electrode, a negative electrode, a separator, and an electrolyte;

[0071] The diaphragm includes a PE base membrane with a thickness of 20 μm and a coating with a thickness of 4 μm located on both sides of the PE base membrane. The coating includes a PVDF-based polymer solid electrolyte and an LATP solid electrolyte.

[0072] The total porosity of the diaphragm is 60%, and the pore size is 20nm~25nm;

[0073] The PE-based film has carboxyl functional groups, which form hydrogen bond structures with the polar groups in PVDF;

[0074] The polymer solid electrolyte also includes lithium trifluoromethanesulfonate, a lithium salt.

[0075] The mass ratio of the polymer solid electrolyte to the LATP solid electrolyte is 2:1.

[0076] The preparation method of the lithium manganese battery is as follows:

[0077] Positive electrode sheet: 90 parts by weight of MnO2 powder and 10 parts by weight of conductive agent are placed in a mixer and stirred evenly. The resulting powder is baked in an oven at 200℃ for 2 hours and then used to prepare the positive electrode sheet. After the positive electrode sheet is prepared, it is baked at 280℃ for 24 hours and then set aside.

[0078] Negative electrode: Lithium metal negative electrode;

[0079] Separator: Mix PVDF-based polymer solid electrolyte, LATP solid electrolyte and solvent to obtain a coating slurry with a solid content of 20%. Coat the coating slurry onto the surfaces of both sides of the PE base film and dry to obtain the separator.

[0080] Electrolyte: A mixed solution of 1 mol / L LiClO4 in ethylene glycol dimethyl ether and propylene carbonate (volume ratio = 1:1) is used as the electrolyte;

[0081] Manganese dioxide positive electrode, lithium metal negative electrode and separator are stacked in the order of positive electrode, separator and negative electrode, and then wound to obtain the cell; the cell is placed in the outer packaging steel shell, the electrolyte is injected into the steel shell, and after vacuum sealing, standing, pre-discharge and aging processes, a lithium manganese primary battery is obtained.

[0082] Example 2

[0083] The difference between this embodiment and Embodiment 1 is that the total porosity of the membrane in this embodiment is 70%, and the pore size is 10nm~20nm; the basic parameters of the corresponding PE base membrane can be adjusted.

[0084] All other conditions remain the same as in Example 1.

[0085] Example 3

[0086] The difference between this embodiment and Embodiment 1 is that the total porosity of the membrane in this embodiment is 38%, and the pore size is 90nm~100nm; the basic parameters of the corresponding PE base membrane can be adjusted.

[0087] All other conditions remain the same as in Example 1.

[0088] Example 4

[0089] The difference between this embodiment and Embodiment 1 is that in the membrane structure of this embodiment, the mass ratio of the polymer solid electrolyte to the LATP solid electrolyte is 1:1.

[0090] All other conditions remain the same as in Example 1.

[0091] Example 5

[0092] The difference between this embodiment and Embodiment 1 is that in the membrane structure of this embodiment, the mass ratio of the polymer solid electrolyte to the LATP solid electrolyte is 1:1.

[0093] All other conditions remain the same as in Example 1.

[0094] Example 6

[0095] The difference between this embodiment and Embodiment 1 is that in the membrane structure of this embodiment, the thickness of the PE base film is 40μm and the thickness of the coating is 2μm.

[0096] All other conditions remain the same as in Example 1.

[0097] Example 7

[0098] The difference between this embodiment and Embodiment 1 is that in the membrane structure of this embodiment, the thickness of the PE base film is 12μm and the thickness of the coating is 3μm.

[0099] All other conditions remain the same as in Example 1.

[0100] Example 8

[0101] The difference between this embodiment and Embodiment 1 is that the polymer of the polymer solid electrolyte in this embodiment is PEO.

[0102] All other conditions remain the same as in Example 1.

[0103] Example 9

[0104] The difference between this embodiment and Embodiment 1 is that the inorganic solid electrolyte in this embodiment is LLZO.

[0105] All other conditions remain the same as in Example 1.

[0106] Example 10

[0107] The difference between this embodiment and Embodiment 1 is that in the membrane structure of this embodiment, the mass ratio of the polymer solid electrolyte to the LATP solid electrolyte is 0.5:1.

[0108] All other conditions remain the same as in Example 1.

[0109] Example 11

[0110] The difference between this embodiment and Embodiment 1 is that in the membrane structure of this embodiment, the mass ratio of the polymer solid electrolyte to the LATP solid electrolyte is 3.5:1.

[0111] All other conditions remain the same as in Example 1.

[0112] Example 12

[0113] The difference between this embodiment and Embodiment 1 is that the thickness of the PE base film in this embodiment is 10 μm.

[0114] All other conditions remain the same as in Example 1.

[0115] Example 13

[0116] The difference between this embodiment and Embodiment 1 is that the coating thickness in this embodiment is 1 μm.

[0117] All other conditions remain the same as in Example 1.

[0118] Example 14

[0119] The difference between this embodiment and Embodiment 1 is that the coating thickness in this embodiment is 5 μm.

[0120] All other conditions remain the same as in Example 1.

[0121] Example 15

[0122] The difference between this embodiment and Embodiment 1 is that the coating in this embodiment is only applied to the surface of the PE base film facing the positive electrode.

[0123] All other conditions remain the same as in Example 1.

[0124] Comparative Example 1

[0125] The difference between this comparative example and Example 1 is that the coating in this comparative example does not contain a polymer solid electrolyte.

[0126] All other conditions remain the same as in Example 1.

[0127] Comparative Example 2

[0128] The difference between this comparative example and Example 1 is that the coating in this comparative example does not contain inorganic solid electrolyte.

[0129] All other conditions remain the same as in Example 1.

[0130] Comparative Example 3

[0131] The difference between this comparative example and Example 1 is that the diaphragm in this comparative example is a pure PE-based membrane.

[0132] Performance testing

[0133] The testing method is as follows:

[0134] The fabricated lithium-manganese batteries were then subjected to high-temperature storage tests, discharge capacity tests, and weight loss rate tests. The test results are shown in Table 1.

[0135] (1) High temperature storage test: The initial internal resistance of the lithium manganese batteries in the examples and comparative examples was measured by the Amber tester. After that, they were placed in an 85°C oven for continuous storage for 6 weeks. After cooling, the internal resistance of the batteries was measured after storage, ensuring that the batteries did not leak.

[0136] (2) Conventional capacity test: The capacity of the lithium manganese batteries in the examples and comparative examples was measured by constant resistance discharge to 2V at 100Ω.

[0137] (3) Weight loss rate: (Battery weight before storage - Battery weight after storage) / Battery weight before storage × 100%.

[0138] Table 1

[0139]

[0140] As shown in Table 1, the lithium-manganese battery in this application exhibits high discharge capacity, low increase in internal resistance after high-temperature storage, and low weight loss. This indicates that the modified separator using polymer solid electrolytes and inorganic solid electrolytes effectively suppresses expansion on the positive electrode side and enhances the electrolyte retention effect. Furthermore, by further controlling the mass ratio of polymer solid electrolytes and inorganic solid electrolytes in the coating and / or the thickness of the base film and coating, a significant improvement in high-temperature storage performance is achieved, along with increased discharge capacity and a marked reduction in weight loss. Moreover, the coating's placement on both sides of the base film further enhances its effectiveness. Conversely, without a coating or lacking any necessary polymer solid electrolyte or inorganic solid electrolyte, the problem of electrolyte accumulation caused by positive electrode expansion cannot be solved, and the discharge capacity also decreases.

[0141] In summary, the lithium-manganese battery of the present invention employs a separator structure with a coating of a polymer solid electrolyte and an inorganic solid electrolyte mixture. This structure improves the ionic conductivity and mechanical strength of the separator. Furthermore, during discharge, as lithium ions continuously insert into the positive electrode to form lithium manganese oxide, the phase structure of the positive electrode changes, and the accompanying side reactions cause the positive electrode to expand. The positive electrode's ability to absorb electrolyte also increases, leading to the electrolyte being concentrated in the positive electrode and consumed by it. The separator structure of the present invention increases the separator's electrolyte retention capacity, solving the problem of reduced electrolyte usage and deteriorated battery performance caused by positive electrode discharge expansion.

[0142] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A lithium manganese battery, characterized in that, The lithium-manganese battery includes a positive electrode, a negative electrode, a separator, and an electrolyte; The positive electrode active material of the positive electrode includes manganese dioxide, and the negative electrode includes a lithium metal negative electrode. The diaphragm includes a base membrane and a coating located on at least one side of the surface of the base membrane, the coating including a polymer solid electrolyte and an inorganic solid electrolyte.

2. The lithium manganese battery according to claim 1, characterized in that, The mass ratio of the polymer solid electrolyte to the inorganic solid electrolyte is (1~3):1; Preferably, the inorganic solid electrolyte is dispersed in the polymer solid electrolyte.

3. The lithium manganese battery according to claim 1, characterized in that, The polymer electrolyte comprises a polymer and a lithium salt; Preferably, the polymer in the polymer solid electrolyte includes any one or a combination of at least two of PEO, PVDF, PVDF copolymer or PAN, and is preferably PVDF and / or PVDF copolymer.

4. The lithium manganese battery according to claim 3, characterized in that, The lithium salts mentioned include any one or a combination of at least two of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate, lithium difluorooxalate borate, lithium trifluoromethanesulfonate, lithium tetrafluoroborate, or lithium difluorophosphate, preferably lithium bis(fluorosulfonyl)imide and / or lithium trifluoromethanesulfonate.

5. The lithium manganese battery according to claim 1 or 3, characterized in that, The inorganic solid electrolyte includes an oxide solid electrolyte, which includes any one or a combination of at least two of the following: perovskite solid electrolyte, NASICON solid electrolyte, or garnet solid electrolyte, preferably NASICON solid electrolyte.

6. The lithium manganese battery according to claim 1, characterized in that, The thickness of the base film is 12μm~30μm, preferably 18μm~30μm; Preferably, the thickness of the coating is 2μm to 4μm.

7. The lithium manganese battery according to claim 1, characterized in that, The total porosity of the diaphragm is 38% to 70%, and the pore size of the diaphragm is 10 nm to 100 nm.

8. The lithium manganese battery according to claim 1, characterized in that, The method for preparing the diaphragm includes: The coating is laminated onto at least one surface of the base film to obtain the separator; Preferably, the composite method includes a slurry coating method, the slurry coating method comprising: A coating slurry is applied to at least one side of the base membrane and dried to obtain the separator. The coating slurry comprises a polymer solid electrolyte, an inorganic solid electrolyte, and a solvent.

9. The lithium manganese battery according to claim 8, characterized in that, The solid content of the coating slurry is 10% to 30%.

10. The lithium manganese battery according to claim 1, characterized in that, The positive electrode includes a positive current collector and a layer of positive active material located on at least one side of the surface of the positive current collector.

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