Primary lithium-manganese battery pack and processing method thereof

Abstract

The invention belongs to the technical field of primary lithium-manganese batteries, and particularly provides a primary lithium-manganese battery pack and a processing method thereof. A primary lithium-manganese battery pack comprises an outer shell and a plurality of single batteries, each single battery comprises a battery shell, an electrode group and an electrolyte, the electrode group and the electrolyte are packaged in the battery shell, the electrode group comprises a positive plate, a negative plate and a diaphragm, the negative plate is formed by compounding a metal lithium plate or a lithium alloy plate and a copper foil, and the diaphragm is a diaphragm. The positive plate is composed of an aluminum foil and a positive active substance coated on the aluminum foil, the positive active substance comprises an electrolytic manganese dioxide composite material, a conductive agent and a binder, and the electrolytic manganese dioxide composite material is prepared by passivating electrolytic manganese dioxide and then grafting a polyether compound. The single battery has good high-temperature storage stability and relatively high discharge capacity at low temperature.

Description

Technical Field

[0001] This application belongs to the field of primary lithium manganese battery technology, and in particular relates to a primary lithium manganese battery pack and its processing method. Background Technology

[0002] A primary battery is a chemical power system that cannot be recharged and reused after discharge. Among them, primary lithium-manganese batteries, which use manganese dioxide as the positive electrode active material and lithium metal as the negative electrode active material, have advantages such as high specific energy, stable discharge, and long storage life. They have been widely used in microelectronic devices, memory backup, smart meters, medical devices, and military equipment.

[0003] With the increasing complexity of terminal devices and the more diverse usage environments, primary lithium manganese batteries are required to have higher energy density, longer lifespan, wider operating temperature range, and more reliable safety. To meet these requirements, multiple primary lithium manganese cells need to be combined into primary lithium manganese battery packs through series, parallel, or series-parallel hybrid connections to obtain higher voltage, larger capacity, and other benefits.

[0004] However, under conditions of high-temperature storage, long-term float charging, or high voltage, when the surface of the manganese dioxide cathode in a primary lithium-manganese battery comes into direct contact with the electrolyte, the unsaturated coordination active sites and oxygen vacancies on the manganese dioxide surface can catalyze the oxidative decomposition of the electrolyte, leading to battery capacity decay and increased internal resistance. Therefore, in a primary lithium-manganese battery pack, inconsistencies exist between multiple individual cells in terms of capacity, internal resistance, and self-discharge rate. During use, these inconsistencies are amplified, triggering a series of accelerated aging, performance degradation, and even safety hazards.

[0005] To reduce electrolyte oxidation, a common method is to modify the electrolyte, for example, by adding antioxidants or using solvents with strong antioxidant properties. Patent application CN120824425A discloses an electrolyte for lithium manganese oxide lithium-ion batteries and its preparation method. This electrolyte includes an organic solvent, a lithium salt, and additives, including a manganese ion complexing agent, a film-forming promoter, and an antioxidant. The antioxidant can inhibit the oxidative decomposition of the electrolyte initiated by manganese ions at high temperatures. However, this method may increase the viscosity of the electrolyte, leading to poor wettability and affecting lithium ion transport, thus causing a decline in battery performance. Summary of the Invention

[0006] To address the aforementioned issues, reduce the oxidative decomposition of the electrolyte, and improve the performance of the battery pack, this application provides a primary lithium-manganese battery pack and its processing method.

[0007] This application first provides a primary lithium-manganese battery pack, including an outer casing and multiple individual cells. Each individual cell includes a battery case, an electrode assembly encapsulated within the battery case, and an electrolyte. The electrode assembly includes a positive electrode, a negative electrode, and a separator. The negative electrode is a composite of a lithium metal sheet or a lithium alloy sheet and copper foil. The positive electrode is composed of aluminum foil and a positive electrode active material coated on the aluminum foil. The positive electrode active material includes an electrolytic manganese dioxide composite material, a conductive agent, and a binder. The preparation method of the electrolytic manganese dioxide composite material includes the following steps: S1: Under nitrogen protection, manganese dioxide is electrolyzed and reacted with aminosilane to obtain aminated manganese dioxide; S2: Aminated manganese dioxide reacts with phosphonic acid to obtain passivated manganese dioxide; S3: Passivated manganese dioxide is reacted with epoxy polyether compounds under nitrogen protection and catalysis to obtain the product.

[0008] Furthermore, the diaphragm is a polyolefin diaphragm.

[0009] Furthermore, the electrolyte is a solution with a concentration of 0.1-1.5 mol / L prepared by dissolving lithium salt in an organic solvent.

[0010] Furthermore, the lithium salt is lithium hexafluorophosphate or lithium tetrafluoroborate; And / or, the organic solvent is an ester solvent.

[0011] Furthermore, the conductive agent is conductive carbon black; and / or, the binder is polyvinylidene fluoride.

[0012] Furthermore, in step S1, the aminosilane is one of γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, and N-(β-aminoethyl)-γ-aminopropyltriethoxysilane; the mass ratio of electrolytic manganese dioxide to aminosilane is 100:(1-5).

[0013] Furthermore, in step S2, the phosphonic acid is one of 2-hydroxyphosphonoacetic acid, 2-carboxyethylphenylphosphine, and 2-phosphobutane-1,2,4-tricarboxylic acid; And / or, the mass ratio of aminated manganese dioxide to phosphonic acid carboxylic acid is 100:(0.5-2).

[0014] Furthermore, in step S2, the catalyst is a Lewis acid.

[0015] Furthermore, in step S3, the epoxy polyether compound is polyethylene glycol diglycidyl ether or polypropylene glycol diglycidyl ether. And / or, the mass ratio of passivated manganese dioxide to epoxy polyether compounds is 100:(1-5).

[0016] This application also provides a method for processing a primary lithium manganese battery pack, including the following steps: (1) The positive electrode, separator and negative electrode are stacked and wound, then inserted into the battery case, the positive and negative electrodes are welded, electrolyte is injected, and the cells are left to stand, sealed, formed, aged, tested and sorted to obtain a single cell. (2) Connect the individual cells electrically, install the protective devices and wires, insulate the whole structure, put it into the outer casing, and finally test, age and inspect.

[0017] Compared with the prior art, this application has the following beneficial effects: 1. This application uses phosphonic acid groups with strong coordination ability to bind with manganese active sites and oxygen vacancies on the surface of electrolytic manganese dioxide, passivating the catalytic oxidation active sites on the surface of manganese dioxide, reducing the catalytic oxidation ability of these active sites on the electrolyte, thereby reducing electrolyte consumption and improving battery life.

[0018] 2. In this application, flexible polyether segments are grafted onto the surface of electrolytic manganese dioxide. The ether oxygen atoms can coordinate with lithium ions, thereby promoting lithium ion transport. Moreover, the flexible segments can also improve the wettability of the electrolyte on the electrode surface, thereby reducing the interfacial impedance.

[0019] 3. The electrolytic manganese dioxide surface of this application can form a stable flexible interface layer, which can effectively block the direct contact between the electrolyte and the manganese dioxide surface, thereby making the electrolyte less susceptible to catalytic oxidation, reducing electrolyte consumption, and extending battery life. Attached Figure Description

[0020] Figure 1 This is an assembly diagram of the battery pack according to Embodiment 1 of this application.

[0021] Figure 2 The curves showing the relative discharge capacity of individual cells in the embodiments and control groups of this application as a function of temperature are shown.

[0022] Explanation of the attached diagram labels: 1 indicates a single cell, 2 indicates an insulating sheet, 3 indicates a terminal, and 4 indicates an outer casing. Detailed Implementation

[0023] To make the inventive objectives, technical solutions, and beneficial technical effects of this application clearer, the following detailed description is provided in conjunction with embodiments, clearly and completely describing the technical solutions in the embodiments of this application. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0025] When using “including,” “having,” and “contains” as described herein, the intention is to cover non-exclusive inclusion, unless an explicit qualifying term such as “only,” “consisting of,” etc., is used, in which case another component may be added.

[0026] The terms "preferred," "more preferably," "better," and "even better" used in this application refer to embodiments of this application that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this application. That is, in this application, "preferred," "more preferably," "better," and "even better" are merely descriptions of implementations or embodiments with better effects, but do not constitute a limitation on the scope of protection of this application.

[0027] In this application, terms such as "further," "even more," and "particularly" are used for descriptive purposes and indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0028] In this application, "at least one" means one or more, such as one, two, or more. "Multiple" or "several" means at least two, such as two, three, etc., and "multi-layered" means at least two layers, such as two layers, three layers, etc., unless otherwise explicitly specified. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise explicitly specified.

[0029] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0030] Unless otherwise specified, all steps in this application may be performed sequentially or randomly. For example, the method comprising steps (a) and (b) indicates that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may 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. Unless otherwise stated, singular terms may include plural forms and should not be construed as having a quantity of one.

[0031] In this application, "above" or "below" includes the number itself. For example, "below 1" includes 1.

[0032] In this application, room temperature refers to 0-40°C, including but not limited to 10-40°C, or further to 20-30°C.

[0033] This application, based on extensive experimental research, provides a primary lithium-manganese battery pack, comprising an outer casing and multiple individual cells. Each individual cell includes a battery casing, an electrode assembly encapsulated within the casing, and an electrolyte. The electrode assembly includes a positive electrode, a negative electrode, and a separator. The negative electrode is a composite of a lithium metal sheet or a lithium alloy sheet and copper foil. The positive electrode is composed of aluminum foil and a positive electrode active material coated on the aluminum foil. The positive electrode active material includes an electrolytic manganese dioxide composite material, a conductive agent, and a binder. The preparation method of the electrolytic manganese dioxide composite material includes the following steps: S1: Under nitrogen protection, manganese dioxide is electrolyzed and reacted with aminosilane to obtain aminated manganese dioxide; S2: Aminated manganese dioxide reacts with phosphonic acid to obtain passivated manganese dioxide; S3: Passivated manganese dioxide is reacted with epoxy polyether compounds under nitrogen protection and catalysis to obtain the product.

[0034] In some embodiments of this application, the phosphonic acid carboxylic acid contains phosphonic acid groups that can strongly interact with active sites, oxygen vacancies, and defects on the surface of electrolytic manganese dioxide. This can partially passivate the surface of electrolytic manganese dioxide, thereby reducing the catalytic oxidation effect of these active sites, oxygen vacancies, and defects on the electrolyte. Furthermore, after grafting flexible polyether compounds onto the passivated manganese dioxide surface, the ether oxygen atoms can coordinate with lithium ions, forming a local environment similar to the electrolyte. This promotes lithium ion transport, making it easier for lithium ions to embed into the manganese dioxide lattice and react. Therefore, it can increase the energy density of the battery pack, improve battery pack stability, and extend battery pack life. In addition, the flexible polyether segments improve the wettability of the electrode surface, thereby reducing interfacial impedance. The flexible polyether segments can also effectively prevent direct contact between the electrolyte and the manganese dioxide surface, making the electrolyte less susceptible to catalytic oxidation. Therefore, it can reduce electrolyte consumption and extend battery pack life.

[0035] In some embodiments of this application, the diaphragm is a polyolefin diaphragm, for example, it can be a polyethylene diaphragm or a polypropylene diaphragm.

[0036] In some embodiments of this application, the electrolyte is a solution with a concentration of 0.1-1.5 mol / L prepared by dissolving lithium salt in an organic solvent; for example, the concentration can be 0.1 mol / L, 0.2 mol / L, 0.5 mol / L, 0.8 mol / L, 1 mol / L, 1.2 mol / L, or 1.5 mol / L.

[0037] In some embodiments of this application, the lithium salt is lithium hexafluorophosphate or lithium tetrafluoroborate; And / or, the organic solvent is an ester solvent, for example, it can be a chain carbonate, cyclic carbonate, chain ester, or cyclic ester.

[0038] In some specific embodiments of this application, the conductive agent is carbon black; and / or, the binder is polyvinylidene fluoride.

[0039] In some embodiments of this application, in step S1, the aminosilane is one of γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, and N-(β-aminoethyl)-γ-aminopropyltriethoxysilane; the mass ratio of electrolytic manganese dioxide to aminosilane is 100:(1-5), for example, it can be 100:1, 100:1.5, 100:2, 100:2.5, 100:3, 100:3.5, 100:4, 100:4.5, or 100:5.

[0040] Aminosilanes can form a strong interaction with the surface of electrolytic manganese dioxide, thereby improving passivation stability and making it less likely for the flexible interface layer to detach, dissolve, or migrate from the surface of electrolytic manganese dioxide during subsequent battery assembly and cycling.

[0041] In some embodiments of this application, in step S2, the phosphonic acid is one of 2-hydroxyphosphonoacetic acid, 2-carboxyethylphenyl hypophosphite, and 2-phosphobutane-1,2,4-tricarboxylic acid; And / or, the mass ratio of aminated manganese dioxide to phosphonic acid is 100:(0.5-2); for example, it can be 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.5, 1:1.8, or 1:2.

[0042] In some embodiments of this application, the catalyst in step S2 is a Lewis acid; more preferably, the catalyst in step S2 is a boron trifluoride diethyl ether complex.

[0043] In some specific embodiments of this application, in step S3, the epoxy polyether compound is polyethylene glycol diglycidyl ether or polypropylene glycol diglycidyl ether. The polyether segments grafted onto the surface of electrolytic manganese dioxide can not only interact with lithium ions, but also have good flexibility, which is conducive to the transport of lithium ions. They can also prevent direct contact between the electrolyte and electrolytic manganese dioxide, thereby reducing the oxidative decomposition of the electrolyte.

[0044] And / or, the mass ratio of passivated manganese dioxide to epoxy polyether compound is 100:(1-5), for example, it can be 100:1, 100:1.5, 100:2, 100:2.5, 100:3, 100:3.5, 100:4, 100:4.5, or 100:5.

[0045] In addition, this application also provides a method for processing a primary lithium manganese battery pack, including the following steps: (1) The positive electrode, separator and negative electrode are stacked and wound, then inserted into the battery case, the positive and negative electrodes are welded, electrolyte is injected, and the cells are left to stand, sealed, formed, aged, tested and sorted to obtain a single cell. (2) Connect the individual cells electrically, install the protective devices and wires, insulate the whole structure, put it into the outer casing, and finally test, age and inspect.

[0046] The present application will be further illustrated by the following examples, but these examples do not limit the scope of the present application.

[0047] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in this application, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. All reagents or instruments whose manufacturers are not specified are conventional products that can be purchased commercially. In addition to the specific methods, equipment, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description in this application, any prior art methods, equipment, and materials similar to or equivalent to those described, used, or made by the methods, equipment, and materials in the embodiments of this application may be used to implement this application.

[0048] Example 1 The primary lithium manganese battery pack of this embodiment includes an outer casing and six individual cells. Each individual cell includes a battery casing, an electrode assembly encapsulated within the battery casing, and an electrolyte. The electrode assembly includes a positive electrode, a negative electrode, and a polypropylene separator. The electrolyte is prepared by: first, mixing γ-valerolactone and propylene carbonate at a volume ratio of 1:1 to obtain a mixed solvent; then, adding lithium hexafluorophosphate to the mixed solvent and mixing it evenly to prepare a solution with a concentration of 1 mol / L. The preparation method of the positive electrode sheet is as follows: weigh 92g of electrolytic manganese dioxide composite material, 4g of acetylene black and 4g of polyvinylidene fluoride, add them to 500mL of N-methylpyrrolidone, mix them evenly, and grind them into a uniform slurry. Then, coat the slurry evenly on the aluminum foil current collector, dry it at 120℃ for 12h, roll it and cut it to obtain the positive electrode sheet. The method for preparing the negative electrode sheet is as follows: high-purity lithium ingots are melted under argon protection, and then rolled into a continuous lithium strip with uniform thickness through a rolling mill. One side of the lithium strip is then laminated onto a copper foil and cut to obtain the desired sheet. The preparation method of the electrolytic manganese dioxide composite material in this embodiment includes the following steps; S1: Weigh 10g of electrolytic manganese dioxide powder and 200mL of toluene, place them in a flask, and sonicate for 30min. Under nitrogen protection, add 0.3g of γ-aminopropyltriethoxysilane while stirring, heat to 80℃, reflux for 12h, cool to room temperature after the reaction, centrifuge, and wash with toluene and ethanol in sequence. Dry the product under vacuum at 60℃ for 6h to obtain aminated manganese dioxide. S2: Weigh 20g of aminated manganese dioxide and 200ml of dimethyl sulfoxide, place them in a flask, and sonicate for 30min to obtain a suspension; weigh 0.2g of 2-hydroxyphosphonoacetic acid, 0.15g of N-hydroxysuccinimide, 0.24g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 20mL of dimethyl sulfoxide, stir for 30min to obtain a phosphonic acid mixture; slowly add the phosphonic acid mixture dropwise to the suspension, heat to 40℃ under nitrogen protection, stir and react for 12h. After the reaction is complete, wash with dimethyl sulfoxide and anhydrous ethanol in sequence, and dry the product under vacuum at 60℃ for 6h to obtain passivated manganese dioxide; S3: Weigh 30g of the above passivated manganese dioxide, add 150mL of tetrahydrofuran, sonicate for 30min, heat to 50℃ under nitrogen protection, add 0.9g of polyethylene glycol diglycidyl ether and 1μL of boron trifluoride diethyl ether complex catalyst in sequence, stir continuously for 6h, after the reaction is completed, cool to room temperature, wash twice with tetrahydrofuran and acetone by centrifugation, and dry the product under vacuum at 60℃ for 12h to obtain the product; The processing method of a primary lithium-manganese battery pack in this embodiment includes the following steps: (1) The positive electrode sheet, polypropylene separator and negative electrode sheet are stacked together in sequence and precisely wound to obtain the core. The core is inserted into the nickel-plated steel shell and then the positive and negative electrodes are welded. In the drying room, the electrolyte is injected into the battery and then left to stand so that the electrolyte is fully wetted. The insulating sealing ring and positive electrode cap assembly are placed in and sealed. Finally, the formation, aging, testing and sorting are carried out to obtain CR17450 single cell. (2) Place the individual cells into a custom bracket in a sequence of three to a group, for a total of two groups. Then, attach insulating sheets to the electrode surfaces of the individual cells, and perform parallel welding, series welding, and total electrode tab welding. Next, install a disposable fuse and weld wires and terminals. After bundling and insulating the whole assembly, place it in an ABS outer shell, fill the gaps with thermally conductive silicone, and finally perform testing, aging, and inspection.

[0049] Control group 1 The primary lithium manganese battery pack in this control group includes an outer casing and six individual cells. Each individual cell includes a battery casing, an electrode assembly encapsulated within the battery casing, and an electrolyte. The electrode assembly includes a positive electrode, a negative electrode, and a polypropylene separator. The electrolyte is prepared by: first, mixing γ-valerolactone and propylene carbonate at a volume ratio of 1:1 to obtain a mixed solvent; then, adding lithium hexafluorophosphate to the mixed solvent and mixing it evenly to prepare a solution with a concentration of 1 mol / L. The preparation method of the positive electrode sheet is as follows: weigh 92g of electrolytic manganese dioxide, 4g of acetylene black and 4g of polyvinylidene fluoride, add them to 500mL of N-methylpyrrolidone, mix them evenly, and grind them into a uniform slurry. Then, coat the slurry evenly on the aluminum foil current collector, dry it at 120℃ for 12h, roll it and cut it to obtain the positive electrode sheet. The method for preparing the negative electrode sheet is as follows: high-purity lithium ingots are melted under argon protection, and then rolled into a continuous lithium strip with uniform thickness through a rolling mill. One side of the lithium strip is then laminated onto a copper foil and cut to obtain the desired sheet. The processing method of the primary lithium manganese battery pack in this control group is the same as that in Example 1.

[0050] Control group 2 The primary lithium manganese battery pack in this control group includes an outer casing and six individual cells. Each individual cell includes a battery casing, an electrode assembly encapsulated within the battery casing, and an electrolyte. The electrode assembly includes a positive electrode, a negative electrode, and a polypropylene separator. The electrolyte is prepared by: first, mixing γ-valerolactone and propylene carbonate at a volume ratio of 1:1 to obtain a mixed solvent; then, adding lithium hexafluorophosphate to the mixed solvent and mixing it evenly to prepare a solution with a concentration of 1 mol / L. The preparation method of the positive electrode sheet is as follows: weigh 92g of electrolytic manganese dioxide composite material, 4g of acetylene black and 4g of polyvinylidene fluoride, add them to 500mL of N-methylpyrrolidone, mix them evenly, and grind them into a uniform slurry. Then, coat the slurry evenly on the aluminum foil current collector, dry it at 120℃ for 12h, roll it and cut it to obtain the positive electrode sheet. The method for preparing the negative electrode sheet is as follows: high-purity lithium ingots are melted under argon protection, and then rolled into a continuous lithium strip with uniform thickness through a rolling mill. One side of the lithium strip is then laminated onto a copper foil and cut to obtain the desired sheet. The preparation method of the electrolytic manganese dioxide composite material in this embodiment includes the following steps; S1: Weigh 10g of electrolytic manganese dioxide powder and 200mL of toluene, place them in a flask, and sonicate for 30min. Under nitrogen protection, add 0.3g of γ-aminopropyltriethoxysilane while stirring, heat to 80℃, reflux for 12h, cool to room temperature after the reaction, centrifuge, and wash with toluene and ethanol in sequence. Dry the product under vacuum at 60℃ for 6h to obtain aminated manganese dioxide. S2: Weigh 20g of aminated manganese dioxide and 200ml of dimethyl sulfoxide, place them in a flask, and sonicate for 30min to obtain a suspension; weigh 0.2g of 2-hydroxyphosphonoacetic acid, 0.15g of N-hydroxysuccinimide, 0.24g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 20mL of dimethyl sulfoxide, stir for 30min to obtain a phosphonic acid mixture; slowly add the phosphonic acid mixture dropwise to the suspension, heat to 40℃ under nitrogen protection, stir and react for 12h. After the reaction is complete, wash with dimethyl sulfoxide and anhydrous ethanol in sequence, and dry the product under vacuum at 60℃ for 6h to obtain the final product. The processing method of the primary lithium manganese battery pack in this control group is the same as that in Example 1.

[0051] Performance testing 1. High-temperature storage performance test: ① Take several formed individual cells from Example 1 and Control Groups 1-2, weigh the initial mass of each individual cell and record it as M0, measure the open circuit voltage at 25°C and record it as OCV0, discharge it at 0.2C rate to 2.0V at 25°C, test the initial capacity and record it as C0, use a battery tester to apply a 1C current pulse (e.g., 1A) for 100ms, calculate ΔV / ΔI, and obtain the DC internal resistance, recorded as DCIR0.

[0052] ② Place the individual cells for which initial data has been recorded in an open-circuit state in a 60℃ oven for 30 days. After removing them, place them in a 25℃, 50%RH environment for 24 hours, and weigh them again using an analytical balance. Record the weight as M. 30 Measure the voltage after storage and record it as OCV. 30 Measure the internal resistance after storage, and record it as DCIR. 30 Measure the remaining capacity of the battery after storage, and record it as C. 30 And calculate the electrolyte consumption rate according to the formula = (M0 - M 30 ) / Injected electrolyte mass × 100%; Capacity retention rate = C 30 / C0×100%;Voltage retention rate = OCV 30 / OCV0×100%;Internal resistance growth rate = (DCIR) 30 -DCIR0) / DCIR0×100%, the measurement results are shown in Table 1.

[0053] Table 1. High-temperature storage performance of single cells in Example 1 and Control Groups 1-2 Comparing the data of the examples and the control group in Table 1, it can be seen that the single cell of Example 1 has better high-temperature storage stability. This indicates that the partial passivation of the electrolytic manganese dioxide surface and the grafting of polyether compounds form a stable flexible interface layer. On the one hand, this effectively reduces the catalytic oxidation of the electrolyte on the electrolytic manganese dioxide surface and may also reduce the side reactions of the negative electrode, thereby reducing the electrolyte consumption rate. On the other hand, it reduces the loss of active materials of the positive and negative electrodes and can promote lithium-ion transport and improve the wettability of the electrode surface. Therefore, the capacity retention rate is high, the interface impedance is reduced, and the internal resistance growth rate is also low.

[0054] 2. Discharge capacity test at different temperatures: Several formed single cells from Example 1 and Control Groups 1-2 were taken. Three single cells were placed at 25°C for 24 hours, and then discharged at a rate of 0.2C to 2.0V. The discharge capacity was tested, and the average value was recorded as the baseline discharge capacity q. 基准 Take another 12 individual batteries, divide them into 4 groups, and place them in test chambers at 0℃, -10℃, -20℃, and -30℃ respectively. Maintain the temperature for 12 hours while keeping the test chambers running, and immediately discharge them to 2.0V at a rate of 0.2C. Record the average discharge capacity of each group as Q0, Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8, Q9, Q10, Q11, Q12, Q12, Q13, Q14, Q15, Q16, Q17, Q18, Q19, Q10 ... -10 Q -20 Q -30 According to the formula, relative discharge capacity = Q / q 基准 Calculate the relative discharge capacity at each temperature using ×100%, and plot the temperature-relative discharge capacity curve, as shown below. Figure 2 As shown.

[0055] contrast Figure 2 The data from the intermediate examples and the control group show that, at the same temperature, the relative discharge capacity of the single cell in Example 1 is higher, indicating that the single cell in Example 1 has better low-temperature stability. This may be because the partial passivation of the surface of electrolytic manganese dioxide and the grafting of polyether compounds can promote lithium-ion transport and reduce charge transfer impedance at low temperatures.

[0056] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A primary lithium-manganese battery pack, characterized in that: The device includes an outer casing and multiple individual battery cells. Each individual battery cell includes a battery case, an electrode assembly encapsulated within the battery case, and an electrolyte. The electrode assembly includes a positive electrode, a negative electrode, and a separator. The negative electrode is composed of a lithium metal sheet or lithium alloy sheet and a copper foil composite. The positive electrode is composed of an aluminum foil and a positive electrode active material coated on the aluminum foil. The positive electrode active material includes an electrolytic manganese dioxide composite material, a conductive agent, and a binder. The preparation method of the electrolytic manganese dioxide composite material includes the following steps: S1: Under nitrogen protection, manganese dioxide is electrolyzed and reacted with aminosilane to obtain aminated manganese dioxide; S2: Aminated manganese dioxide reacts with phosphonic acid to obtain passivated manganese dioxide; S3: Passivated manganese dioxide is reacted with epoxy polyether compounds under nitrogen protection and catalysis to obtain the product.

2. The primary lithium-manganese battery pack according to claim 1, characterized in that: The diaphragm is a polyolefin diaphragm.

3. A primary lithium-manganese battery pack according to claim 1, characterized in that: The electrolyte is a 0.1-1.5 mol / L solution prepared by dissolving lithium salt in an organic solvent.

4. A primary lithium-manganese battery pack according to claim 3, characterized in that: The lithium salt is lithium hexafluorophosphate or lithium tetrafluoroborate; and / or, the organic solvent is an ester solvent.

5. A primary lithium-manganese battery pack according to claim 1, characterized in that: The conductive agent is conductive carbon black; and / or the binder is polyvinylidene fluoride.

6. A primary lithium-manganese battery pack according to claim 1, characterized in that: In step S1, the aminosilane is one of γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, and N-(β-aminoethyl)-γ-aminopropyltriethoxysilane; the mass ratio of electrolytic manganese dioxide to aminosilane is 100:(1-5).

7. A primary lithium-manganese battery pack according to claim 1, characterized in that: In step S2, the phosphonic acid is one of 2-hydroxyphosphonoacetic acid, 2-carboxyethylphenyl hypophosphite, and 2-phosphobutane-1,2,4-tricarboxylic acid. And / or, the mass ratio of aminated manganese dioxide to phosphonic acid carboxylic acid is 100:(0.5-2).

8. A primary lithium-manganese battery pack according to claim 1, characterized in that: In step S2, the catalyst is a Lewis acid.

9. A primary lithium-manganese battery pack according to claim 1, characterized in that: In step S3, the epoxy polyether compound is polyethylene glycol diglycidyl ether or polypropylene glycol diglycidyl ether. And / or, the mass ratio of passivated manganese dioxide to epoxy polyether compounds is 100:(1-5).

10. A method for processing a primary lithium-manganese battery pack according to any one of claims 1-9, characterized in that: Includes the following steps: (1) The positive electrode, separator and negative electrode are stacked and wound, then inserted into the battery case, the positive and negative electrodes are welded, electrolyte is injected, and the cells are left to stand, sealed, formed, aged, tested and sorted to obtain a single cell. (2) Connect the individual cells electrically, install the protective devices and wires, insulate the whole structure, put it into the outer casing, and finally test, age and inspect.

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