Lithium-manganese battery, manufacturing method thereof and electric device

Abstract

This invention belongs to the field of battery technology. It provides a lithium-manganese battery, its manufacturing method, and an electrical device. The positive electrode active material in the positive electrode sheet of the lithium-manganese battery includes manganese dioxide. The separator of the lithium-manganese battery includes a base film and a functional coating disposed on the base film. The functional coating includes a mixture of inorganic solid electrolyte and aramid fiber. By combining the solid electrolyte and aramid fiber to form the functional coating on the base film, on the one hand, more uniform positive and negative electrode interface contact can be provided, promoting efficient ion transport; on the other hand, the inorganic solid electrolyte is non-flammable, and combined with the high strength characteristics of aramid fiber, the separator formed after coating can significantly reduce the risk of thermal runaway or fire in the battery.

Description

Technical Field

[0001] This invention belongs to the field of battery technology and relates to a lithium manganese battery, its manufacturing method, and an electrical device thereof. Background Technology

[0002] Currently, lithium-manganese dioxide primary batteries, as typical non-rechargeable lithium primary batteries, are widely used in fields with stringent reliability requirements, such as smart meters, medical implants, military equipment, and IoT terminals, due to their high operating voltage (approximately 3.0V), high specific energy, excellent storage stability, and wide temperature range adaptability.

[0003] Unlike rechargeable lithium-ion batteries, lithium-manganese primary batteries differ fundamentally in their design goals and application scenarios: they do not require consideration of cycle life, but instead emphasize high reliability after long-term storage, stability of the discharge platform, and safety performance under extreme environments. Especially in high-temperature environments, lithium-manganese batteries must maintain structural integrity during storage periods of several years or even decades and stably output rated capacity after activation, placing extremely high demands on the thermal stability of the material system. However, this battery system still faces significant safety risks under high-temperature conditions. On the one hand, the activity of the lithium metal anode increases at high temperatures, making it prone to side reactions with the electrolyte, generating an unstable solid electrolyte interface film, leading to increased self-discharge, gas production, and even increased internal pressure. On the other hand, the manganese dioxide cathode may experience lattice distortion or oxygen release under high temperatures or deep discharge conditions, inducing a thermal reaction upon contact with the organic electrolyte, further exacerbating heat accumulation. Furthermore, if the internal separator shrinks or melts at high temperatures, it may cause a short circuit between the positive and negative electrodes, triggering a thermal runaway chain reaction, posing a fire or explosion hazard. Especially under the trend of high energy density design, the increase in electrode loading and the decrease in porosity further exacerbate the heat accumulation and heat dissipation difficulties.

[0004] Therefore, current technologies still have significant shortcomings in terms of high-temperature performance and thermal runaway suppression. There is an urgent need to develop a new type of lithium manganese primary battery with inherent safety characteristics in terms of material system, interface design and thermal management mechanism to meet the dual requirements of high-temperature environmental adaptability and safety in high-end application scenarios. Summary of the Invention

[0005] In view of the problems existing in the prior art, the purpose of the present invention is to provide a lithium manganese battery, a method for manufacturing the same, and an electrical device thereof. The positive electrode active material in the positive electrode sheet of the lithium manganese battery includes manganese dioxide; the separator of the lithium manganese battery includes a base film and a functional coating disposed on the base film; the functional coating includes an inorganic solid electrolyte and aramid fibers mixed together; by combining the solid electrolyte and aramid fibers to form the functional coating on the base film, on the one hand, more uniform positive and negative electrode interface contact can be provided, promoting efficient ion transport; on the other hand, the inorganic solid electrolyte is not flammable, and combined with the high strength characteristics of aramid fibers, the separator formed after coating can significantly reduce the risk of thermal runaway or fire in the battery.

[0006] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a lithium manganese battery, comprising a positive electrode and a negative electrode disposed opposite to each other, and a separator disposed between the positive electrode and the negative electrode; the positive electrode comprises a positive electrode active material including manganese dioxide; the separator comprises a base film and a functional coating disposed on the base film; the functional coating comprises an inorganic solid electrolyte and aramid fibers mixed together.

[0007] This invention uses a specific separator in lithium manganese batteries, namely, a functional coating formed on the base film by combining solid electrolyte with aramid fiber. On the one hand, it can provide more uniform positive and negative electrode interface contact and promote efficient ion transport. On the other hand, the inorganic solid electrolyte is not flammable, and combined with the high strength characteristics of aramid fiber, the separator formed after coating can significantly reduce the risk of thermal runaway or fire in the battery.

[0008] 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 technical solutions.

[0009] As a preferred embodiment of the present invention, the thickness of the functional coating is 2μm to 4μm. Exemplarily, the thickness of the functional coating can be 2μm, 2.2μm, 2.4μm, 2.6μm, 2.8μm, 3μm, 3.2μm, 3.4μm, 3.6μm, 3.8μm, or 4μm, etc.

[0010] As a preferred embodiment of the present invention, in the functional coating, the mass ratio of the inorganic solid electrolyte to the aramid fiber is (2~3):1. Exemplarily, the mass ratio of the inorganic solid electrolyte to the aramid fiber can be 2:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, or 3:1, etc.

[0011] In this invention, the solid electrolyte can improve the temperature resistance, safety, ionic conductivity, and electrolyte wettability of the diaphragm; aramid fiber can improve the temperature resistance, safety, and mechanical strength of the diaphragm. If the proportion is too high, the high content of inorganic solid electrolyte will reduce the toughness of the composite diaphragm coating, potentially causing coating cracking and peeling during use, thus increasing costs; if the proportion is too low, the low content of inorganic solid electrolyte will limit the improvement in electrolyte wettability of the composite diaphragm.

[0012] As a preferred embodiment of the present invention, the functional coating further includes an adhesive; the adhesive includes PVDF (polyvinylidene fluoride).

[0013] As a preferred embodiment of the present invention, the base film is made of PP (polypropylene) and / or PE (polyethylene). The base film can be prepared using a dry process.

[0014] As a preferred embodiment of the present invention, the base film has pores with a porosity of 38% to 70% and a pore size of 10 nm to 100 nm. For example, the porosity of the base film can be 38%, 40%, 45%, 50%, 55%, 60%, 65%, or 70%, etc.; the pore size of the base film can be 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, or 100 nm, etc.

[0015] As a preferred embodiment of the present invention, the thickness of the base film is 12μm to 40μm. Exemplarily, the thickness of the base film can be 12μm, 15μm, 18μm, 20μm, 23μm, 25μm, 28μm, 30μm, 33μm, 35μm, 38μm, or 40μm, etc.

[0016] As a preferred embodiment of the present invention, the inorganic solid electrolyte particles include oxide solid electrolytes.

[0017] As a preferred technical solution of the present invention, the oxide solid electrolyte includes at least one of garnet-type solid electrolyte, NASION-type solid electrolyte, or perovskite-type solid electrolyte.

[0018] As a preferred technical solution of the present invention, the garnet-type solid electrolyte includes LLZO (such as Li7La3Zr2O). 12 ) and / or LLZTO (such as Li 6.4 La3Zr 1.4 Ta 0.6 O 12 ).

[0019] As a preferred technical solution of the present invention, the NASION-type solid electrolyte includes LATP (such as Li 1.3Al 0.3 Ti 1.7 (PO4)3), LAGP (such as Li 1.4 Al 0.4 Ge 1.6 (PO4)3) or LZSP (Li3Zr2Si2PO4) 12 At least one of the following.

[0020] As a preferred technical solution of the present invention, the perovskite-type solid electrolyte includes LLTO (such as Li) 0.33 La 0.56 TiO3).

[0021] As a preferred embodiment of the present invention, the inorganic solid electrolyte has pores with a porosity of 38% to 70% and a pore size of 10 nm to 100 nm. For example, the porosity of the inorganic solid electrolyte can be 38%, 40%, 45%, 50%, 55%, 60%, 65%, or 70%, etc.; the pore size of the inorganic solid electrolyte can be 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, or 100 nm, etc.

[0022] As a preferred technical solution of the present invention, the particle size range of the inorganic solid electrolyte is 0.3μm~2μm, for example, it can be 0.3μm, 0.5μm, 0.8μm, 1μm, 1.3μm, 1.5μm, 1.8μm or 2μm, etc.

[0023] As a preferred embodiment of the present invention, the aspect ratio of the aramid fiber is (50~50000):1, and the diameter is 0.1μm~5μm. Exemplarily, the aspect ratio of the aramid fiber can be 50:1, 60:1, 80:1, 100:1, 120:1, 140:1, 160:1, 180:1, 200:1, 300:1, 500:1, 800:1, 1000:1, 3000:1, 5000:1, 10000:1, 30000:1, or 50000:1, etc., preferably (…). 500~50000):1; The diameter can be 0.1μm, 0.15μm, 0.2μm, 0.25μm, 0.3μm, 0.35μm, 0.4μm, 0.45μm, 0.5μm, 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm or 5μm, etc., preferably 0.5μm~1.5μm.

[0024] Preferably, the length of the aramid fiber is 1mm to 5mm, for example, it can be 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm or 5mm, etc.

[0025] The high aspect ratio of aramid fibers helps enhance the mechanical properties of composite materials while maintaining good flowability and coating uniformity. Finer fibers can provide higher strength and better interfacial bonding, but care must be taken to avoid excessive fineness, which can lead to decreased conductivity or slurry flowability issues.

[0026] It is understood that, in addition to the positive electrode active material manganese dioxide, the positive electrode sheet also includes a positive electrode current collector and a positive electrode active layer disposed on the positive electrode current collector. The positive electrode active layer includes the positive electrode active material manganese dioxide, as well as a conductive agent and a binder.

[0027] Preferably, the conductive agent includes at least one of graphite, conductive carbon black, acetylene black, graphene, or carbon nanotubes.

[0028] Preferably, the adhesive comprises at least one of polytetrafluoroethylene, styrene-butadiene rubber, ethylene-acrylic acid copolymer, or polyvinylidene fluoride and its modifiers.

[0029] Preferably, based on the mass of the positive electrode active layer as 100%, the mass percentage of the positive electrode active material is 88%~92%, such as 88%, 88.5%, 88.8%, 89%, 89.2%, 89.6%, 90%, 90.3%, 90.6%, 91%, 91.2%, 91.5%, or 92%; the mass percentage of the conductive agent is 6%~8%, such as 6%, 6.2%, 6.4%, 6.6%, 6.8%, 7%, 7.2%, 7.4%, 7.6%, 7.8%, or 8%; and the mass percentage of the binder is 2%~4%, such as 2%, 2.3%, 2.5%, 2.8%, 3.2%, 3.5%, 3.8%, or 4%.

[0030] Preferably, the positive current collector comprises a steel mesh or aluminum steel.

[0031] As a preferred embodiment of the present invention, the negative electrode sheet comprises lithium metal or lithium alloy.

[0032] Preferably, the doped metal element in the lithium alloy includes at least one of aluminum, magnesium, or calcium; based on the total mass of the negative electrode sheet (100%), the mass percentage of the doped metal element is 0.05% to 3%, for example, 0.05%, 0.08%, 0.1%, 0.13%, 0.15%, 0.18%, 0.3%, 0.5%, 0.8%, 1%, 1.3%, 1.5%, 1.8%, 2%, 2.3%, 2.5%, 2.8%, or 3%.

[0033] As a preferred embodiment of the present invention, the lithium manganese battery further includes a non-aqueous electrolyte, which comprises lithium salt and organic solvent.

[0034] Preferably, the lithium salt includes at least one of LiClO4, LiFSI, LiBOB, or LiTFSI.

[0035] Preferably, the organic solvent includes at least one selected from ethylene carbonate, butyl carbonate, diethyl carbonate, methyl ethyl carbonate, 1,2-dimethoxyethane, or 1,2-diethoxyethane.

[0036] Preferably, the injection volume of the non-aqueous electrolyte is 0.05 g / Ah to 0.5 g / Ah, for example, 0.5 g / Ah, 0.1 g / Ah, 0.15 g / Ah, 0.2 g / Ah, 0.25 g / Ah, 0.3 g / Ah, 0.35 g / Ah, 0.4 g / Ah, 0.45 g / Ah, or 0.5 g / Ah.

[0037] The functional coating containing inorganic solid electrolyte and aramid fiber can improve the electrolyte wettability of the separator. Both the positive and negative electrodes still require sufficient electrolyte wetting to reduce interfacial impedance. As the battery discharges, some electrolyte is consumed, necessitating replenishment with free electrolyte to maintain good ionic conductivity.

[0038] As a preferred technical solution of the present invention, the lithium manganese battery includes any one of button cell, cylindrical cell, or pouch cell, preferably a cylindrical cell.

[0039] In a second aspect, the present invention provides a method for manufacturing the lithium manganese battery described in the first aspect, the method comprising: We provide positive electrode plates, negative electrode plates, and base films; Inorganic solid electrolytes and aramid fibers are mixed to form a slurry, which is then coated on one or both sides of the base membrane. After drying, a functional coating is formed, resulting in a diaphragm. The separator is arranged between the positive and negative electrodes to form an assembly. A non-aqueous electrolyte is injected into the assembly, and post-processing is performed to obtain a lithium manganese battery.

[0040] As a preferred technical solution of the present invention, the manufacturing method includes: providing an adhesive solution, adding an inorganic solid electrolyte and aramid fiber to the adhesive solution and mixing them to form the slurry.

[0041] Preferably, the adhesive solution comprises a PVDF adhesive solution with a solid content of 8% to 12%, for example, it can be 8%, 9%, 10%, 11% or 12%, etc.

[0042] As a preferred embodiment of the present invention, the solvent of the slurry includes N-methylpyrrolidone (NMP) and / or dimethyl sulfoxide (DMSO) solution. Further, the solvent of the adhesive solution may be NMP and / or DMSO.

[0043] Preferably, the solid content of the slurry is 90% to 98%, for example, it can be 90%, 90.5%, 91%, 91.5%, 92%, 92.5%, 93%, 93.5%, 94%, 94.5%, 95%, 95.5%, 96%, 96.5%, 97%, 97.5%, or 98%, etc., preferably 95%. Solid content refers to the percentage by mass of the total mass of inorganic solid electrolyte and aramid fiber in the slurry.

[0044] Preferably, the drying process includes a first drying at 60℃~100℃, such as 60℃, 70℃, 80℃, 90℃ or 100℃, and a second drying at 100℃~120℃, such as 100℃, 105℃, 110℃, 115℃ or 120℃.

[0045] Preferably, the total drying time is 5 min to 6 min, for example, it can be 5 min, 5.2 min, 5.5 min, 5.8 min or 6 min, etc.

[0046] Furthermore, a continuous segmented oven can be used to dry the diaphragm. After coating, the diaphragm is pulled by rollers into a temperature range of 60℃~100℃ to remove most of the solvent. Then it enters a temperature range of 100℃~120℃ to crystallize the PVDF molecular chains and fix the solid electrolyte and aramid fibers on the base film. Further, the diaphragm surface can be rolled to make the coating smoother and denser.

[0047] Furthermore, after the diaphragm is coated on one or both sides, dried and cured, and then wound up, the entire roll of diaphragm is placed in an oven at 70℃~90℃ and heated for 30 minutes to remove residual trace amounts of NMP solvent and ensure complete crystallization of PVDF.

[0048] As a preferred technical solution of the present invention, the assembly method includes a lamination-pressing process and / or a rolling process; As a preferred technical solution of the present invention, the post-processing includes at least one of encapsulation, pre-discharge, or aging.

[0049] Thirdly, the present invention provides an electrical device comprising the lithium manganese battery described in the first aspect.

[0050] It should be noted that, due to space limitations and to avoid redundancy, this invention does not exhaustively list all point values ​​within the above numerical range, but it is not limited to the listed values ​​either; other unlisted values ​​within the above numerical range are also applicable.

[0051] Compared with existing technical solutions, the present invention has at least the following beneficial effects: In the lithium-manganese battery provided by the present invention, the positive electrode includes a positive electrode active material including manganese dioxide, and the separator includes a base film and a functional coating disposed on the base film; the functional coating includes an inorganic solid electrolyte and aramid fibers mixed together; by combining the solid electrolyte and aramid fibers to form the functional coating on the separator, on the one hand, more uniform positive and negative electrode interface contact can be provided to promote efficient ion transport; on the other hand, the inorganic solid electrolyte is not flammable, and combined with the high strength characteristics of aramid fibers, the separator formed after coating can significantly reduce the risk of thermal runaway or fire in the battery. Detailed Implementation

[0052] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0053] Those skilled in the art will understand that the embodiments described are merely illustrative of the invention and should not be construed as limiting the invention.

[0054] Example 1 This embodiment provides a lithium manganese battery, including a positive electrode and a negative electrode disposed opposite to each other, and a separator disposed between the positive electrode and the negative electrode; The positive electrode sheet includes a positive current collector steel mesh or aluminum steel and a positive active layer disposed on both sides of the positive current collector. Calculated with the mass of the positive active layer as 100%, the positive active layer includes 89.5% positive active material manganese dioxide, 7.2% conductive agent graphite, and 3.3% binder polyvinylidene fluoride.

[0055] The diaphragm comprises a base membrane (PP) and functional coatings disposed on both sides of the base membrane. The base membrane has a thickness of 20 μm and is porous with a porosity of 38%–70% and a pore size of 10 nm–100 nm. The functional coating has a thickness of 2 μm and comprises an inorganic solid electrolyte (LLZO) and aramid fibers mixed together in a mass ratio of 2.5:1. The inorganic solid electrolyte is porous with a porosity of 60%–80%, a pore size of 10 nm–50 nm, and a particle size of 0.3 μm–2 μm. The aramid fibers have an aspect ratio of 50000:1–500:1, a length of 1 mm–5 mm, and a diameter of 0.1 μm–2 μm. The negative electrode is lithium metal; The lithium-manganese battery further includes a non-aqueous electrolyte, which comprises lithium salt LiFSI and organic solvents ethylene carbonate, diethyl carbonate, and methyl ethyl carbonate. The injection volume of the non-aqueous electrolyte is 1.8 g / Ah.

[0056] This embodiment also provides a method for manufacturing the lithium manganese battery, the method comprising: We provide positive electrode plates, negative electrode plates, and base films; NMP solvent and PVDF adhesive with a solid content of 8%~12% are provided. Inorganic solid electrolyte and aramid fiber are added to the PVDF adhesive in portions, and the mixture is mechanically stirred at 300 rpm for 30 minutes to form a uniform and stable slurry. The base membrane is then unwound and cleaned to remove surface dust and oil. The resulting slurry is then uniformly coated onto the base membrane using a strip extrusion die. Drying is then performed; specifically, the coated diaphragm is drawn into an oven by rollers and dried in stages. First, it is baked at 60℃~100℃ to allow the slurry solvent to evaporate slowly; then the temperature is increased to 100℃~120℃ to ensure the PVDF molecular chains crystallize and bond firmly to the base membrane. The total residence time in the oven is 5~6 minutes. After the diaphragm is coated on both sides, dried and cured, and then wound up, the entire roll of diaphragm is transferred to an oven at 70℃~90℃ and heated for 30 minutes to remove residual trace amounts of NMP solvent and ensure complete PVDF crystallization, resulting in a ready-to-use diaphragm with a functional coating. The assembly is formed by placing the separator between the positive and negative electrodes, and a non-aqueous electrolyte is injected into the assembly. The assembly is then encapsulated, pre-discharged, or aged sequentially to obtain a lithium manganese battery.

[0057] Example 2 This embodiment provides a lithium manganese battery. In the functional coating of the separator of the lithium manganese battery, the mass ratio of inorganic solid electrolyte LLZO to aramid fiber is adjusted from 2.5:1 to 1:1. Except for the above, the other conditions are exactly the same as in Embodiment 1.

[0058] Example 3 This embodiment provides a lithium manganese battery. In the functional coating of the separator of the lithium manganese battery, the mass ratio of inorganic solid electrolyte LLZO to aramid fiber is adjusted from 2.5:1 to 2:1. Except for the above, the other conditions are exactly the same as in Embodiment 1.

[0059] Example 4 This embodiment provides a lithium manganese battery. In the functional coating of the separator of the lithium manganese battery, the mass ratio of inorganic solid electrolyte LLZO to aramid fiber is adjusted from 2.5:1 to 3:1. Except for the above, the other conditions are exactly the same as in Embodiment 1.

[0060] Example 5 This embodiment provides a lithium manganese battery. In the functional coating of the separator of the lithium manganese battery, the mass ratio of inorganic solid electrolyte LLZO to aramid fiber is adjusted from 2.5:1 to 4:1. Except for the above, the other conditions are exactly the same as in Embodiment 1.

[0061] Example 6 This embodiment provides a lithium manganese battery. In the functional coating of the separator of the lithium manganese battery, the diameter of the aramid fiber is adjusted from 0.2 μm to 0.1 μm, so that the aspect ratio changes from 10000:1 to 20000:1. Except for the above, the other conditions are exactly the same as in Embodiment 1.

[0062] Example 7 This embodiment provides a lithium manganese battery. In the functional coating of the separator of the lithium manganese battery, the diameter of the aramid fiber is adjusted from 0.2 μm to 0.4 μm, so that the aspect ratio changes from 10000:1 to 5000:1. Except for the above, the other conditions are exactly the same as in Embodiment 1.

[0063] Example 8 This embodiment provides a lithium manganese battery. In the functional coating of the separator of the lithium manganese battery, the diameter of the aramid fiber is adjusted from 0.2 μm to 0.8 μm, so that the aspect ratio changes from 10000:1 to 2500:1. Except for the above, the other conditions are exactly the same as those in Embodiment 1.

[0064] Example 9 This embodiment provides a lithium manganese battery in which the inorganic solid electrolyte is replaced by LATP in the functional coating of the separator of the lithium manganese battery, except that the other conditions are exactly the same as in embodiment 1.

[0065] Example 10 This embodiment provides a lithium manganese battery in which the inorganic solid electrolyte is replaced by LLTO in the functional coating of the separator. Except for the above, the other conditions are exactly the same as in Embodiment 1.

[0066] Comparative Example 1 This comparative example provides a lithium manganese battery in which an inorganic solid electrolyte is not used in the functional coating of the separator. Except for the above, the other conditions are exactly the same as in Example 1.

[0067] Comparative Example 2 This comparative example provides a lithium manganese battery in which the inorganic solid electrolyte is replaced with inorganic particulate Al2O3 in the functional coating of the separator. Except for the above, the other conditions are exactly the same as in Example 1.

[0068] Comparative Example 3 This comparative example provides a lithium manganese battery in which inorganic solid electrolyte and aramid fiber are not used in the functional coating of the separator. Except for the above, the other conditions are exactly the same as in Example 1.

[0069] Comparative Example 4 This comparative example provides a lithium manganese battery in which a base film is used as a separator and no functional coating is provided. Except for the above, the other conditions are exactly the same as those in Example 1.

[0070] The performance of the separators obtained in the examples and comparative examples was tested, or the electrochemical performance of the obtained lithium manganese batteries was tested. Five samples were tested for each test and each scheme, and the average value was calculated. Specifically, the following was included: 1) Diaphragm electrolyte wettability test: Cut a 100mm×100mm diaphragm, drop 0.1mL of electrolyte into the center of the diaphragm, and test the diffusion diameter of the electrolyte; 2) Diaphragm temperature resistance test: Cut a 100mm×100mm diaphragm piece, place it at 120℃ for 1 hour, and then test the thermal shrinkage rate of the diaphragm. 3) Diaphragm tensile strength test: The tensile strength of the diaphragm is tested according to the standard method GB / T 1040.3-2006; 4) Diaphragm puncture strength: The puncture strength of the diaphragm is tested according to the standard method GB / T 36363-2018; 5) Membrane ionic conductivity: Cut a 20mm diameter membrane disc and immerse it in electrolyte at room temperature for 20 minutes until the membrane pores are completely filled. Place the membrane into a CR2032 battery mold in a glove box and assemble the battery using stainless steel sheets as electrodes. Use an electrochemical workstation to test the impedance and ionic conductivity of the simulated battery.

[0071] The test results are shown in the table below.

[0072] Table 1. Effect of solid electrolyte to aramid fiber mass ratio on membrane performance. Table 2. Effects of aramid fiber diameter and aspect ratio on membrane performance. Table 3. Effects of different solid electrolytes on membrane performance. Table 4. Effect of coating composition on diaphragm performance. Combining Tables 1 to 4, we can see that: Examples 1-5 compared the effect of the mass ratio of solid electrolyte to aramid fiber on the membrane performance. Table 1 shows that the particulate solid electrolyte has a higher specific surface area and porosity than aramid fiber. The scheme with a higher proportion of solid electrolyte has better electrolyte affinity and capacity. The ionic conductivity of the membrane increases with the increase of the membrane's hydrophilicity, and the interfacial impedance of the membrane decreases. The ionic conductivity of Example 1 is higher than that of Example 2. Aramid fiber improves the mechanical properties of the membrane; the puncture strength of Example 1 is higher than that of Example 5.

[0073] Example 1 compared the effects of the diameter and aspect ratio of aramid fibers on the performance of the diaphragm with Examples 6 to 8. As can be seen from the data in Table 2, the aspect ratio of aramid fibers affects the microstructure of the fibers. Fibers with a high aspect ratio entangle with each other to form a dense three-dimensional network structure, resulting in a diaphragm with higher mechanical strength and thermal stability. This is manifested in the increased tensile strength and decreased area shrinkage rate of the diaphragm at high temperatures due to the higher aspect ratio.

[0074] Example 1 compared the effects of different solid electrolytes on membrane performance with Examples 9 and 10. The data in Table 3 show that among the solid electrolytes LLZO, LATP, and LLTO, LLZO exhibits the highest affinity and chemical compatibility with the electrolyte and lithium metal, possesses high bulk ionic conductivity, and good wettability in a semi-solid environment; LLTO has high ionic conductivity and moderate wettability, but it reacts with lithium metal; LATP has good air stability and relatively high conductivity, but it reacts with lithium metal, and is only coated on the side in contact with the positive electrode, resulting in slightly poorer wettability.

[0075] Example 1 compared the effects of coating composition on membrane performance with Comparative Examples 1 to 4. The data in Table 3 show that: Example 1 compared with Comparative Example 1 indicates that the acid-washed solid electrolyte LLZO has good hydrophilicity, increasing the diffusion diameter of the electrolyte on the membrane and improving the ionic conductivity of the finished membrane; Example 1 compared with Comparative Example 2 indicates that aramid fiber plays an important role in improving the puncture strength of the membrane and reducing the thermal shrinkage rate, while its affinity for the electrolyte is slightly lower than that of the solid electrolyte LLZO; Example 1 compared with Comparative Example 3 indicates that the solid electrolyte LLZO has a higher affinity for the electrolyte than Al2O3.

[0076] As can be seen from the above, in the lithium manganese battery provided by the present invention, the positive electrode includes a positive electrode active material including manganese dioxide, and the separator includes a base film and a functional coating disposed on the base film; the functional coating includes an inorganic solid electrolyte and aramid fibers mixed together; by combining the solid electrolyte and aramid fibers to form the functional coating on the separator, on the one hand, it can provide a more uniform positive and negative electrode interface contact and promote efficient ion transport; on the other hand, the inorganic solid electrolyte is not flammable, and combined with the high strength characteristics of aramid fibers, the separator formed after coating can significantly reduce the risk of thermal runaway or fire in the battery.

[0077] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0078] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0079] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A lithium manganese battery, characterized in that, The device includes a positive electrode and a negative electrode arranged opposite to each other, and a separator disposed between the positive electrode and the negative electrode; the positive electrode includes a positive active material including manganese dioxide; the separator includes a base membrane and a functional coating disposed on the base membrane; the functional coating includes an inorganic solid electrolyte and aramid fibers mixed together.

2. The lithium manganese battery according to claim 1, characterized in that, The thickness of the functional coating is 2μm~4μm; Preferably, in the functional coating, the mass ratio of the inorganic solid electrolyte to the aramid fiber is (2~3):

1. Preferably, the functional coating further includes an adhesive; the adhesive includes PVDF; Preferably, in the functional coating, the adhesive accounts for 4% to 10% of the total mass.

3. The lithium manganese battery according to claim 1 or 2, characterized in that, The base film is made of PP and / or PE. Preferably, the base film has pores with a porosity of 38% to 70% and a pore size of 10 nm to 100 nm; Preferably, the thickness of the base film is 12μm to 40μm.

4. The lithium manganese battery according to any one of claims 1-3, characterized in that, The inorganic solid electrolyte includes an oxide solid electrolyte; Preferably, the oxide solid electrolyte includes at least one of garnet-type solid electrolyte, NASION-type solid electrolyte, or perovskite-type solid electrolyte; Preferably, the garnet-type solid electrolyte comprises LLZO and / or LLZTO; Preferably, the NASION-type solid electrolyte includes at least one of LATP, LAGP, or LZSP; Preferably, the perovskite solid electrolyte comprises LLTO; Preferably, the inorganic solid electrolyte has pores with a porosity of 38% to 70% and a pore size of 10 nm to 100 nm. Preferably, the particle size range of the inorganic solid electrolyte is 0.3 μm to 2 μm.

5. The lithium manganese battery according to any one of claims 1-4, characterized in that, The aspect ratio of the aramid fiber is (50~50000):1, preferably (500~50000):1; Preferably, the diameter of the aramid fiber is 0.1 μm to 5 μm, more preferably 0.5 μm to 1.5 μm; Preferably, the length of the aramid fiber is 1mm to 5mm.

6. The lithium manganese battery according to any one of claims 1-5, characterized in that, The negative electrode sheet comprises lithium metal or a lithium alloy; Preferably, the lithium manganese battery further includes a non-aqueous electrolyte, which comprises lithium salt and organic solvent.

7. The lithium manganese battery according to any one of claims 1-6, characterized in that, The lithium manganese battery includes any one of button cells, cylindrical cells, or pouch cells, preferably cylindrical cells.

8. A method for manufacturing a lithium manganese battery according to any one of claims 1-7, characterized in that, The manufacturing method includes: We provide positive electrode plates, negative electrode plates, and base films; Inorganic solid electrolytes and aramid fibers are mixed to form a slurry, which is then coated on one or both sides of the base membrane. After drying, a functional coating is formed, resulting in a diaphragm. The separator is arranged between the positive and negative electrodes to form an assembly. A non-aqueous electrolyte is injected into the assembly, and post-processing is performed to obtain a lithium-manganese battery.

9. The method for manufacturing a lithium manganese battery according to claim 8, characterized in that, The manufacturing method includes: providing an adhesive solution, adding an inorganic solid electrolyte and aramid fibers to the adhesive solution and mixing them to form the slurry; Preferably, the adhesive solution comprises a PVDF adhesive solution with a solid content of 8% to 12%; Preferably, the solvent of the slurry includes N-methylpyrrolidone and / or dimethyl sulfoxide; Preferably, the solid content of the slurry is 90%~98%; Preferably, the drying process includes a first drying at 60°C to 100°C, followed by a second drying at 100°C to 120°C. Preferably, the assembly method includes a lamination-pressing process and / or a roll forming process; Preferably, the post-processing includes at least one of encapsulation, pre-discharge, or aging.

10. An electrical device, characterized in that, The lithium manganese battery comprising any one of claims 1-7.

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