Battery cell, hot melt adhesive, preparation method, battery device and electric equipment

Abstract

The application relates to the technical field of batteries, in particular to a battery monomer, hot melt adhesive, a preparation method and an electric device, an aluminum alloy material contains the following chemical components in mass fractions: maleic anhydride modified polyethylene, 20-50 parts; random polypropylene, 20-50 parts; terpene phenol resin, 15-40 parts; antioxidant, 0.1-1 part. The hot melt adhesive in the battery monomer has strong electrolyte resistance and high bonding strength with metal materials, can reduce the probability of the hot melt adhesive falling off due to electrolyte immersion, and improve the probability of voltage reduction and capacity attenuation caused thereby.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to battery cells, hot melt adhesives, preparation methods, battery devices, and electrical equipment. Background Technology

[0002] With the rapid development of society, the demand for green new energy and high-performance energy storage equipment is becoming increasingly urgent. Batteries, as a new generation of green energy storage and conversion devices, have been widely used in portable electronic devices and electric vehicles. In some applications, colloids are required inside the battery. However, because the battery interior needs to be filled with electrolyte, conventional colloids are prone to detachment under the immersion of the electrolyte, causing the hot melt adhesive to fail. Summary of the Invention

[0003] In view of this, the main technical problem to be solved by this application is to provide a battery cell, hot melt adhesive, preparation method, battery device and electrical equipment. The battery cell includes hot melt adhesive, which has good resistance to electrolyte and can reduce the probability of hot melt adhesive falling off due to electrolyte soaking, and reduce the probability of debris falling into the battery cell and causing a short circuit in the battery cell.

[0004] To solve the above-mentioned technical problems, one technical solution adopted in this application is: to provide a battery cell, the battery cell including hot melt adhesive, the hot melt adhesive containing the following chemical components in parts by mass: maleic anhydride modified polyethylene, 20 parts to 50 parts; atactic polypropylene, 20 parts to 50 parts; terpene phenol resin, 15 parts to 40 parts; antioxidant, 0.1 parts to 1 part.

[0005] In the technical solution of this application, the battery cell includes a hot melt adhesive, which comprises maleic anhydride-modified polyethylene, atactic polypropylene, terpene phenol resin, and an antioxidant. The maleic anhydride-modified polyethylene, by modifying the polyethylene with maleic anhydride, increases polarity, giving the modified polyethylene a stronger polarity. This increases its affinity with metal materials such as copper and aluminum sheets, thus improving the bonding strength between the hot melt adhesive and these materials. In this application, the atactic polypropylene exhibits high crystallinity, good high-temperature resistance, is not easily carbonized or oxidized, is easy to cure, has excellent electrolyte resistance, and the adhesive does not produce stringiness. In this application, the maleic anhydride-modified polyethylene and atactic polypropylene work together to control the... The hot melt adhesive achieves rapid curing and high-temperature resistance by using 20-50 parts by weight of maleic anhydride-modified polyethylene and 20-50 parts by weight of atactic polypropylene. In this embodiment, terpene phenol resin increases the initial tack of the hot melt adhesive, resulting in stronger adhesion when the hot melt adhesive comes into contact with metal materials. Terpene phenol resin is also highly flexible, which improves the impact resistance of the hot melt adhesive. It has strong compatibility with maleic anhydride-modified polyethylene and atactic polypropylene. As a non-polar resin, terpene phenol resin has low compatibility with electrolytes and exhibits high electrolyte resistance and stability. In this embodiment, by controlling the mass of terpene phenol resin to be 15-40 parts, the hot melt adhesive achieves strong electrolyte resistance. In this embodiment, the hot melt adhesive is reduced in probability by adding an antioxidant. By controlling the mass fraction of the antioxidant to be 0.1 to 1 part, the hot melt adhesive achieves better antioxidant effect while also improving its fluidity and viscosity. In this embodiment, the hot melt adhesive in the battery cell has strong affinity and high bonding strength with the metal material, making it less prone to detachment. It also exhibits strong electrolyte resistance, preventing detachment from electrolyte immersion within the battery cell. This reduces the probability of short circuits caused by hot melt adhesive detachment, thereby reducing the likelihood of voltage drop and capacity decay.

[0006] In any embodiment, the hot melt adhesive contains the following chemical components by weight: maleic anhydride-modified polyethylene, 35 to 45 parts; atactic polypropylene, 35 to 45 parts; terpene phenol resin, 15 to 25 parts; and antioxidant, 0.2 to 0.8 parts. In this embodiment, controlling the weight of the above components within the aforementioned range is beneficial for improving the synergistic effect of maleic anhydride-modified polyethylene, atactic polypropylene, and terpene phenol resin. This improves the flexibility of the hot melt adhesive, enhances its impact resistance, improves its high-temperature resistance, improves its affinity with metal materials, improves its electrolyte resistance, reduces the probability of hot melt adhesive detachment from battery cells, and lowers the probability of voltage drop and capacity decay resulting from this.

[0007] In any embodiment, the mass percentage of atactic polypropylene is 20% to 50% based on the total mass of the hot melt adhesive. In the embodiments of this application, the mass percentage of atactic polypropylene is within the above range based on the total mass of the hot melt adhesive, which makes the hot melt adhesive have better electrolyte resistance, better high temperature resistance and better oxidation resistance.

[0008] In any embodiment, the number average molecular weight of the maleic anhydride-modified polyethylene is 10,000 to 100,000. In the embodiments of this application, by controlling the number average molecular weight of the maleic anhydride-modified polyethylene within the above range, the maleic anhydride-modified polyethylene has more stable properties and better adhesion, flowability, cohesive strength, and electrolyte resistance.

[0009] In any embodiment, the number average molecular weight of atactic polypropylene is 10,000 to 100,000. In the embodiments of the application, by controlling the number average molecular weight of atactic polypropylene within the above range, atactic polypropylene exhibits better flexibility and superior electrolyte resistance, thus achieving better compatibility with maleic anhydride-modified polyethylene.

[0010] In any embodiment, the number-average molecular weight of the terpene phenol resin is 500 to 2000. In the embodiments described above, by controlling the number-average molecular weight of the terpene phenol resin within the above range, the hot melt adhesive exhibits better viscosity and flowability, facilitating its application. Simultaneously, it also enhances the flexibility and impact resistance of the hot melt adhesive.

[0011] In any embodiment, the antioxidant includes one or more of carbodiimide, hindered phenol, butylphenol, and butylphenol derivatives. In the embodiments of this application, the above-mentioned oxidant can effectively reduce the probability of oxidation or thermal decomposition of the hot melt adhesive.

[0012] In any embodiment, the grafting rate of maleic anhydride onto polyethylene in maleic anhydride-modified polyethylene is 2% to 4%. By controlling the grafting ratio, the bonding performance, rapid curing, high temperature resistance, and immersion resistance of the hot melt adhesive can be controlled.

[0013] In any embodiment, the battery cell includes a housing, an electrode assembly, and an adapter plate. The housing has an accommodating space and a terminal post is disposed on the housing. The electrode assembly is disposed within the accommodating space and has at least one tab. The adapter plate electrically connects the tab and the terminal post, and the adapter plate and the terminal post are connected by welding, forming a welding area on the side of the adapter plate away from the terminal post. Hot melt adhesive covers the welding area to form a protective layer. In this embodiment, by covering the welding area with hot melt adhesive, the hot melt adhesive forms a protective layer, thereby fixing welding slag and other particles on the welding area. At the same time, the hot melt adhesive has strong adhesion to the adapter plate, strong resistance to electrolyte, and low expansion in electrolyte, making it less prone to falling off. This reduces the probability of short circuits in the battery cell caused by welding slag and other particles entering the battery cell due to hot melt adhesive falling off.

[0014] In any embodiment, the thickness of the protective layer is 0.5 mm to 5 mm. In the embodiments of this application, by controlling the thickness of the protective layer within the above range, the hot melt adhesive can cover the welding slag and other particles formed during welding, reducing the probability of the welding slag and other particles overflowing. On the other hand, the hot melt adhesive has strong adhesion within the above thickness range and is not easy to fall off.

[0015] In any embodiment, the battery cell includes an electrolyte, which includes a solvent, including ester solvents. In the embodiments of this application, maleic anhydride-modified polyethylene has strong polarity, and the hot melt adhesive has low swelling degree in ester solvents, thus exhibiting good resistance to ester electrolytes.

[0016] The second aspect of this application also includes a hot melt adhesive, which contains the following chemical components by weight: maleic anhydride-modified polyethylene, 20-50 parts; atactic polypropylene, 20-50 parts; terpene phenol resin, 15-40 parts; and antioxidant, 0.1-1 part. In this embodiment, the hot melt adhesive includes maleic anhydride-modified polyethylene, atactic polypropylene, terpene phenol resin, and antioxidant. The maleic anhydride-modified polyethylene, by modifying the polyethylene with maleic anhydride, increases polarity, giving the modified polyethylene a stronger polarity, which increases its affinity with metal materials such as copper and aluminum sheets, thus improving the bonding strength between the hot melt adhesive and these metal materials. In this embodiment, the atactic polypropylene has high crystallinity, good high-temperature resistance, is not easily carbonized or oxidized, is easy to cure, has excellent electrolyte resistance, and the adhesive does not produce stringiness. In this embodiment, the maleic anhydride-modified polyethylene and atactic polypropylene work synergistically. By controlling the content of maleic anhydride-modified polyethylene and atactic polypropylene within the aforementioned range, the hot melt adhesive achieves rapid curing and high-temperature resistance. In this embodiment, terpene phenol resin increases the initial tack of the hot melt adhesive, resulting in stronger adsorption when the hot melt adhesive contacts metal materials. The high flexibility of terpene phenol resin improves its impact resistance. It also exhibits strong compatibility with maleic anhydride-modified polyethylene and atactic polypropylene. As a non-polar resin, terpene phenol resin has low compatibility with electrolytes, resulting in high electrolyte resistance and stability. Furthermore, by controlling the content of terpene phenol resin within the aforementioned range, the hot melt adhesive demonstrates strong electrolyte resistance. In this embodiment, the addition of antioxidants reduces the probability of oxidation or thermal decomposition of the hot melt adhesive. Finally, the hot melt adhesive exhibits strong affinity and high bonding strength with metal materials, is not easily detached, and demonstrates strong electrolyte resistance, making it suitable for use in battery cells.

[0017] In any embodiment, the adhesion strength of the hot melt adhesive to the metal material after soaking in the electrolyte for 90 days is 529 N / m to 565 N / m. In the embodiments of this application, the hot melt adhesive has a low degree of expansion after being soaked in the electrolyte, and the bonding strength between the hot melt adhesive and the metal material is reduced to a certain extent. When the reduction is low, a high adhesion strength can be maintained, making the hot melt adhesive less likely to fall off.

[0018] The third aspect of this application also includes a method for preparing a hot melt adhesive, comprising mixing 20-50 parts by weight of maleic anhydride-modified polyethylene, 20-50 parts by weight of atactic polypropylene, 15-40 parts by weight of terpene phenol resin, and 0.1-1.0 parts by weight of antioxidant, and stirring at 150°C-180°C to obtain a hot melt adhesive. In the embodiments of this application, the above method facilitates the mixing of the above materials and the preparation of a hot melt adhesive, and the prepared hot melt adhesive has the same advantages as the hot melt adhesive of the second aspect.

[0019] In any embodiment, the stirring speed is 100 rpm to 300 rpm. In the embodiments of this application, by controlling the stirring speed within the above range, it is beneficial to ensure that the maleic anhydride modified polyethylene, atactic polypropylene, terpene phenol resin and antioxidant are mixed evenly, thereby improving the uniformity of the hot melt adhesive.

[0020] In any embodiment, the stirring time is 10 min to 30 min. In the embodiments of this application, controlling the stirring speed within the above range is beneficial to improving the uniformity of the mixing of maleic anhydride modified polyethylene, atactic polypropylene, terpene phenol resin and antioxidant.

[0021] In any embodiment, the stirring atmosphere is a vacuum. In the embodiments of this application, by controlling the stirring speed within the above-mentioned range, it is beneficial to reduce the occurrence of side reactions during the hot melt adhesive preparation process and improve the stability of the hot melt adhesive.

[0022] The fourth aspect of this application also includes a battery device comprising a battery cell of the first aspect, and / or a hot melt adhesive of the second aspect, and / or a hot melt adhesive prepared by the preparation method of the third aspect. The battery device of the embodiments of this application has the same advantages as the battery cell of the first aspect, and / or has the same advantages as the hot melt adhesive of the second aspect, and / or has the same advantages as the hot melt adhesive prepared by the preparation method of the third aspect.

[0023] The fifth aspect of this application also includes an electrical device comprising a battery cell of the first aspect, and / or a hot melt adhesive of the second aspect, and / or a hot melt adhesive prepared by the preparation method of the third aspect, and / or a battery device of the fourth aspect. The electrical device of the embodiments of this application has the same advantages as the battery cell of the first aspect, and / or has the same advantages as the hot melt adhesive of the second aspect, and / or has the same advantages as the hot melt adhesive prepared by the preparation method of the third aspect, and / or has the same advantages as the battery device of the fourth aspect. Attached Figure Description

[0024] Figure 1 This is a structural schematic diagram of one embodiment of the vehicle described in this application.

[0025] Figure 2 This is an exploded structural diagram of one embodiment of the battery device of this application.

[0026] Figure 3 This is an exploded structural diagram of one embodiment of the battery cell of this application.

[0027] Figure 4 This is a schematic diagram of the structure of one embodiment of the battery cell of this application.

[0028] Figure 5 This is a partial structural schematic diagram of one embodiment after the end cap and the adapter piece of this application are welded together. Detailed Implementation

[0029] The following detailed description, with appropriate reference to the accompanying drawings, specifically discloses embodiments of the battery cell, battery, and electrical device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0030] The "range" disclosed in this application is defined by 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 a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, 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 a specific parameter, it is understood that ranges of 60–110 and 80–120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, 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 "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0031] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0032] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0033] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably 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, if the method may also include step (c), it means 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.

[0034] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0035] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0036] During the manufacturing process of a battery cell, the terminals and adapter plates on the end caps of the battery cell are connected by welding. During the welding process, welding slag and other particles are easily generated. In addition, the adapter plate has a pit structure design, and there are pit structures around the welding points, which makes it easy for welding slag and other particles to remain at the welding points and in the surrounding area. Related technologies use glue to seal and fix the welding slag and other particles, but the electrolyte in the battery cell can easily reach the welding points, which can easily cause the glue to fall off or swell, causing the welding slag and other particles to fall off. The welding slag and other particles entering the cell can easily cause micro short circuits or short circuits in the cell or module, resulting in problems such as leakage from the battery cell casing and self-discharge of the battery cell.

[0037] Therefore, some embodiments of this application provide a battery cell, the battery cell including hot melt adhesive, the hot melt adhesive containing the following chemical components in parts by weight: maleic anhydride modified polyethylene, 20 parts to 50 parts; atactic polypropylene, 20 parts to 50 parts; terpene phenol resin, 15 parts to 40 parts; antioxidant, 0.1 parts to 1 part.

[0038] In the technical solution of this application, the battery cell includes a hot melt adhesive, which comprises maleic anhydride-modified polyethylene, atactic polypropylene, terpene phenol resin, and an antioxidant. The maleic anhydride-modified polyethylene, by modifying the polyethylene, increases its polarity, giving it strong polarity and increasing its affinity for metal materials such as copper and aluminum sheets, thus improving the bonding strength between the hot melt adhesive and these materials. In this application, the atactic polypropylene exhibits high crystallinity, good high-temperature resistance, is not easily carbonized or oxidized, is easy to cure, has excellent electrolyte resistance, and the adhesive does not produce stringiness. In this application, the maleic anhydride-modified polyethylene and atactic polypropylene work synergistically, by controlling the maleic anhydride... The hot melt adhesive achieves rapid curing and high-temperature resistance by using 20-50 parts by weight of anhydride-modified polyethylene and 20-50 parts by weight of atactic polypropylene. In this embodiment, terpene phenol resin increases the initial tack of the hot melt adhesive, resulting in stronger adhesion when the hot melt adhesive comes into contact with metal materials. Terpene phenol resin is also highly flexible, which improves the impact resistance of the hot melt adhesive. It has strong compatibility with maleic anhydride-modified polyethylene and atactic polypropylene. As a non-polar resin, terpene phenol resin has low compatibility with electrolytes and exhibits high electrolyte resistance and stability. In this embodiment, by controlling the mass percentage of terpene phenol resin to be 15-40 parts, the hot melt adhesive achieves strong electrolyte resistance. In this embodiment, by adding antioxidants to the raw materials of the hot melt adhesive, the probability of oxidation or thermal decomposition of the hot melt adhesive can be reduced. By controlling the mass fraction of the antioxidant to be 0.1 to 1 part, the hot melt adhesive can achieve better antioxidant effect, while also improving its fluidity and viscosity. In this embodiment, the hot melt adhesive in the battery cell has strong affinity and high bonding strength with the metal material, making it less prone to detachment. It also exhibits strong resistance to electrolytes and is not easily detached from the battery cell due to immersion in electrolyte. This reduces the probability of short circuits caused by hot melt adhesive detachment from the battery cell, thereby reducing the probability of voltage drop and capacity decay.

[0039] The hot melt adhesive, categorized by mass parts, can contain maleic anhydride-modified polyethylene in quantities of 20, 23, 25, 28, 30, 33, 35, 37, 40, or 50 parts, or any range of two of these values, such as 20-28, 28-33, or 33-50 parts. Similarly, the hot melt adhesive can contain atactic polypropylene in quantities of 20, 23, 25, 27, 30, 33, 36, 37, 40, or 50 parts, or any range of two of these values, such as 20-27, 27-36, or 36-50 parts. Hot melt adhesives are categorized by weight parts, with terpene phenol resin comprising 15, 17, 19, 20, 22, 23, 25, 27, 30, 35, and 40 parts, or any range of two of these values, such as 15-19, 19-23, or 23-40 parts. Hot melt adhesives are also categorized by weight parts, with antioxidants comprising 0.1, 0.2, 0.4, 0.5, 0.7, and 1 part, or any range of two of these values, such as 0.1-0.4, 0.4-0.7, or 0.7-1 part.

[0040] In the embodiments of this application, the proportions of maleic anhydride modified polyethylene, atactic polypropylene, terpene phenol resin, antioxidant, and other components in the hot melt adhesive are all by weight. For example, 20 parts is 20 parts by weight, 50 parts is 50 parts by weight, 40 parts is 40 parts by weight, etc.

[0041] In this embodiment, the components of maleic anhydride modified polyethylene, atactic polypropylene, terpene phenol resin and antioxidant in hot melt adhesive can be separated and tested by methods such as gas chromatography-mass spectrometry (GC-MS), headspace gas chromatography-mass spectrometry (HS-GCMS), pyrolysis-gas chromatography-mass spectrometry (Py-GCMS), infrared spectroscopy, and nuclear magnetic resonance (NMR). The mass fraction of each substance can be obtained by weighing and measuring the mass of the separated substances.

[0042] In any embodiment, the hot melt adhesive contains the following chemical components by weight: maleic anhydride-modified polyethylene, 35 to 45 parts; atactic polypropylene, 35 to 45 parts; terpene phenol resin, 15 to 25 parts; and antioxidant, 0.2 to 0.8 parts. In this embodiment, controlling the weight of the above components within the aforementioned range is beneficial for improving the synergistic effect of maleic anhydride-modified polyethylene, atactic polypropylene, and terpene phenol resin. This improves the flexibility of the hot melt adhesive, enhances its impact resistance, improves its high-temperature resistance, improves its affinity with metal materials, improves its electrolyte resistance, reduces the probability of hot melt adhesive detachment from battery cells, and lowers the probability of voltage drop and capacity decay resulting from this. The hot melt adhesives, categorized by mass parts, include maleic anhydride-modified polyethylene in parts of 35, 38, 39, 40, 43, 45, or any range of two of these values, such as 35-39, 39-43, or 43-45. Similarly, atactic polypropylene, categorized by mass parts, includes 35, 37, 40, 43, 45, or any range of two of these values, such as 35-37, 37-43, or 43-45. Finally, terpene phenolic resin, categorized by mass parts, includes 15, 18, 19, 20, 22, 23, 25, or any range of two of these values, such as 15-20, 20-23, or 23-25. Hot melt adhesives are classified by the number of parts by weight, with antioxidants accounting for 0.1 parts, 0.2 parts, 0.4 parts, 0.5 parts, 0.7 parts, 1 part, etc., or any range of two of the above values, such as 0.1 parts to 0.4 parts, 0.4 parts to 0.7 parts, 0.7 parts to 1 part, etc.

[0043] In any embodiment, the mass percentage of atactic polypropylene based on the total mass of the hot melt adhesive is 20% to 50%. In the embodiments of this application, the mass percentage of atactic polypropylene based on the total mass of the hot melt adhesive falling within the above range results in better electrolyte resistance, higher temperature resistance, and oxidation resistance of the hot melt adhesive. Specifically, the mass percentage of atactic polypropylene based on the total mass of the hot melt adhesive is 20%, 23%, 25%, 27%, 30%, 33%, 36%, 37%, 40%, or 50%, or a range consisting of any two of the above values, for example, 20% to 27%, 27% to 36%, 36% to 50%, etc.

[0044] In this embodiment, atactic polypropylene is a random copolymer of polypropylene.

[0045] In any embodiment, the number-average molecular weight of the maleic anhydride-modified polyethylene is 10,000 to 100,000. In this application, by controlling the number-average molecular weight of the maleic anhydride-modified polyethylene within the above range, the maleic anhydride-modified polyethylene exhibits more stable properties, including better adhesion, flowability, cohesive strength, and electrolyte resistance. The number-average molecular weight of the maleic anhydride-modified polyethylene can be 10,000, 30,000, 40,000, 48,000, 50,000, 80,000, 100,000, or a range consisting of any two of the above values, such as 10,000–48,000, 48,000–80,000, or 80,000–10,000.

[0046] Among them, number-average molecular weight is common knowledge in the field and has a common meaning in the field. It can be measured by methods and instruments in the field, such as by a laser particle size analyzer.

[0047] In any embodiment, the number-average molecular weight of atactic polypropylene is 10,000 to 100,000. In the embodiments described above, by controlling the number-average molecular weight of atactic polypropylene within the above range, the atactic polypropylene exhibits better flexibility and superior electrolyte resistance, resulting in better compatibility with maleic anhydride-modified polyethylene. The number-average molecular weight of atactic polypropylene can be 10,000, 30,000, 40,000, 45,000, 50,000, 86,000, 100,000, or a range consisting of any two of the above values, such as 10,000–45,000, 45,000–86,000, 86,000–10,000, etc.

[0048] In any embodiment, the number-average molecular weight of the terpene phenol resin is 500–2000. In the embodiments described above, by controlling the number-average molecular weight of the terpene phenol resin within this range, the hot melt adhesive exhibits better viscosity and flowability, facilitating its application. This reduces the likelihood of clogging the dispensing nozzle and preventing stringing when using dispensing equipment. Simultaneously, it enhances the flexibility and impact resistance of the hot melt adhesive. The number-average molecular weight of the terpene phenol resin can be 500, 800, 1000, 1300, 1500, 2000, or any range of two of the above values, such as 1500–800, 800–1300, or 1300–2000.

[0049] In any embodiment, the antioxidant includes one or more of carbodiimide, hindered phenol, butylphenol, and butylphenol derivatives. In the embodiments of this application, the above-mentioned oxidant can effectively reduce the probability of oxidation or thermal decomposition of the hot melt adhesive.

[0050] In any embodiment, the grafting rate of maleic anhydride onto polyethylene in maleic anhydride-modified polyethylene is 2% to 4%. The bonding performance, rapid curing, high-temperature resistance, and immersion resistance of the hot melt adhesive are controlled by adjusting the grafting ratio.

[0051] In this embodiment of the application, the grafting rate of maleic anhydride-modified polyethylene onto atactic polypropylene was tested using an infrared spectroscopy analyzer. The measured infrared spectrum showed a grafting rate at a wavenumber of 1780 cm⁻¹. ～1 Absorption peaks are present at positions to the left and right, and the grafting rate is determined based on the intensity of the absorption peaks.

[0052] In any implementation, such as Figures 3-5 As shown, the battery cell 20 includes a housing 21, which forms an accommodating space (not shown in the figure), and a terminal post 212 is disposed on the housing 21. In this embodiment, the housing 21 includes a main housing 211 and an end cap 213. The terminal post 212 is disposed on the end cap 213. In other embodiments, the terminal post 212 may also be disposed at other locations on the housing 21.

[0053] The battery cell 20 also includes an electrode assembly 23 and an adapter plate 24. The electrode assembly 23 is disposed within the accommodating space and has at least one tab 231. The adapter plate 24 electrically connects the tab 231 and the terminal post 212. The adapter plate 24 and the terminal post 212 are connected by welding, and a welding area 25 is formed on the side of the adapter plate 24 away from the terminal post 212. Hot melt adhesive covers the welding area 25 to form a protective layer 26. In this embodiment, by covering the welding area 25 with hot melt adhesive, the hot melt adhesive forms a protective layer 26, thereby fixing welding slag and other particles on the welding area 25. At the same time, the hot melt adhesive has strong adhesion to the adapter plate 24, strong resistance to electrolyte, and low expansion in electrolyte, making it less prone to falling off. This reduces the probability of short circuit in the battery cell 20 caused by welding slag and other particles entering the battery cell 20 due to hot melt adhesive falling off.

[0054] In one embodiment of this application, the hot melt adhesive may only cover the welding area 25. Alternatively, the hot melt adhesive may cover the welding area 25 and extend to cover its outer periphery. The outer periphery of the welding area 25 refers to a portion of the area outside the welding area 25, which may be a continuous area surrounding the welding area 25, or a non-connected area around the welding area 25. In this embodiment, the welding area 25 is the bottom portion of the recessed structure of the adapter piece 24, and the protective layer 26 covers the welding area 25, other areas at the bottom of the recessed structure (the non-welded area at the bottom of the recessed structure), and a portion of the area outside the recessed structure of the adapter piece. In other embodiments, the protective layer 26 may only cover the bottom area of ​​the recessed structure, i.e., cover the welding area 25 and the non-welded area at the bottom of the recessed structure. Or, the protective layer 26 may only cover the welding area 25, fixing weld slag and other particles on the welding area 25.

[0055] In any embodiment, the thickness of the protective layer 26 is 0.5mm to 5mm. In this embodiment, by controlling the thickness of the protective layer within the above range, the hot melt adhesive can, on the one hand, cover the weld slag and other particles formed during welding, reducing the probability of these particles overflowing; on the other hand, the hot melt adhesive has strong adhesion within the above thickness range, making it less prone to detachment. The thickness of the protective layer can be 0.5mm, 1mm, 2mm, 3mm, 4mm, 5mm, etc., or a range consisting of any two of the above values, such as 0.5mm to 2mm, 2mm to 3mm, 3mm to 5mm, etc.

[0056] In this embodiment of the application, the thickness of the protective layer 26 is the average thickness of the protective layer 26.

[0057] In this embodiment, the battery cell includes an electrolyte, which includes a solvent, and the solvent includes ester solvents. In this embodiment, maleic anhydride-modified polyethylene has strong polarity, and the hot melt adhesive has low swelling degree in ester solvents, thus exhibiting good resistance to ester electrolytes. In this embodiment, the ester solvent includes one or more of the following: ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, and 1,4-butyrolactone.

[0058] In some embodiments of this application, the electrolyte further includes an electrolyte salt. In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0059] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0060] The second aspect of this application also includes a hot melt adhesive, which contains the following chemical components by weight: maleic anhydride-modified polyethylene, 20-50 parts; atactic polypropylene, 20-50 parts; terpene phenol resin, 15-40 parts; and antioxidant, 0.1-1 part. In this embodiment, the hot melt adhesive includes maleic anhydride-modified polyethylene, atactic polypropylene, terpene phenol resin, and antioxidant. The maleic anhydride-modified polyethylene, by modifying the polyethylene with maleic anhydride, increases polarity, giving the modified polyethylene a stronger polarity, which increases its affinity with metal materials such as copper and aluminum sheets, thus improving the bonding strength between the hot melt adhesive and these metal materials. In this embodiment, the atactic polypropylene has high crystallinity, good high-temperature resistance, is not easily carbonized or oxidized, is easy to cure, has excellent electrolyte resistance, and the adhesive does not produce stringiness. In this embodiment, the maleic anhydride-modified polyethylene and atactic polypropylene work synergistically. By controlling the content of maleic anhydride-modified polyethylene and atactic polypropylene within the aforementioned range, the hot melt adhesive achieves rapid curing and high-temperature resistance. In this embodiment, terpene phenol resin increases the initial tack of the hot melt adhesive, resulting in stronger adsorption when the hot melt adhesive contacts metal materials. The high flexibility of terpene phenol resin improves its impact resistance. It also exhibits strong compatibility with maleic anhydride-modified polyethylene and atactic polypropylene. As a non-polar resin, terpene phenol resin has low compatibility with electrolytes, resulting in high electrolyte resistance and stability. Furthermore, by controlling the content of terpene phenol resin within the aforementioned range, the hot melt adhesive demonstrates strong electrolyte resistance. In this embodiment, the addition of antioxidants reduces the probability of oxidation or thermal decomposition. Finally, the hot melt adhesive exhibits strong affinity and high bonding strength with metal materials, is less prone to detachment, and demonstrates strong electrolyte resistance, making it suitable for use in battery cells. The hot melt adhesive, categorized by mass parts, can contain maleic anhydride-modified polyethylene in quantities of 20, 23, 25, 28, 30, 33, 35, 37, 40, or 50 parts, or any range of two of these values, such as 20-28, 28-33, or 33-50 parts. Similarly, the hot melt adhesive can contain atactic polypropylene in quantities of 20, 23, 25, 27, 30, 33, 36, 37, 40, or 50 parts, or any range of two of these values, such as 20-27, 27-36, or 36-50 parts. Hot melt adhesives are classified by mass parts, with terpene phenol resin comprising 15, 17, 19, 20, 22, 23, 25, 27, 30, 40 parts, or any range of two of the above values, such as 15 to 19 parts, 19 to 23 parts, 23 to 40 parts, etc.Hot melt adhesives are classified by the number of parts by weight, with antioxidants accounting for 0.1 parts, 0.2 parts, 0.4 parts, 0.5 parts, 0.7 parts, 1 part, etc., or any range of two of the above values, such as 0.1 parts to 0.4 parts, 0.4 parts to 0.7 parts, 0.7 parts to 1 part, etc.

[0061] In any embodiment, the adhesion strength of the hot melt adhesive to the metal material after soaking in the electrolyte for 90 days is 529 N / m to 565 N / m. In this embodiment, the hot melt adhesive has a low degree of expansion after soaking in the electrolyte, and the bonding strength between the hot melt adhesive and the metal material is reduced to a certain extent. When the reduction is low, a high adhesion strength can be maintained, making the hot melt adhesive less likely to fall off. The adhesion strength of the hot melt adhesive to the metal material after soaking in the electrolyte for 90 days can be 529 N / m, 530 N / m, 538 N / m, 545 N / m, 550 N / m, 554 N / m, 558 N / m, 560 N / m, 565 N / m, etc., or a range of any two of the above values, such as 529 N / m to 538 N / m, 538 N / m to 554 N / m, 554 N / m to 565 N / m, etc.

[0062] The third aspect of this application also includes a method for preparing a hot melt adhesive, comprising mixing 20-50 parts by weight of maleic anhydride-modified polyethylene, 20-50 parts by weight of atactic polypropylene, 15-40 parts by weight of terpene phenol resin, and 0.1-1.0 parts by weight of antioxidant, and stirring at 150°C-180°C to obtain a hot melt adhesive. In the embodiments of this application, the above method facilitates the mixing of the above materials and the preparation of a hot melt adhesive, and the prepared hot melt adhesive has the same advantages as the hot melt adhesive of the second aspect. The stirring temperature can be 150°C, 155°C, 160°C, 166°C, 170°C, 180°C, etc., or a range of any two of the above values, for example, 150°C-155°C, 155°C-166°C, 166°C-180°C, etc.

[0063] In any embodiment, the stirring speed is 100 rpm to 300 rpm. In this embodiment, controlling the stirring speed within the above range helps to ensure uniform mixing of maleic anhydride-modified polyethylene, atactic polypropylene, terpene phenol resin, and antioxidant, thereby improving the uniformity of the hot melt adhesive. The stirring speed can be 100 rpm, 150 rpm, 180 rpm, 195 rpm, 200 rpm, 265 rpm, 300 rpm, etc., or a range of any two of the above values, such as 100 rpm to 180 rpm, 180 rpm to 265 rpm, 180 rpm to 265 rpm, etc.

[0064] In any embodiment, the stirring time is 10 min to 30 min. In this embodiment, controlling the stirring speed within the above range is beneficial to improving the uniformity of the mixture of maleic anhydride-modified polyethylene, atactic polypropylene, terpene phenol resin, and antioxidant. The stirring speed can be 10 min, 15 min, 18 min, 20 min, 25 min, 27 min, 30 min, etc., or a range of any two of the above values, for example, 10 min to 18 min, 18 min to 27 min, 27 min to 30 min, etc.

[0065] In any embodiment, the stirring atmosphere is a vacuum. In the embodiments of this application, by controlling the stirring speed within the above-mentioned range, it is beneficial to reduce the occurrence of side reactions during the hot melt adhesive preparation process and improve the stability of the hot melt adhesive.

[0066] The fourth aspect of this application also includes a battery device comprising a battery cell of the first aspect, and / or a hot melt adhesive of the second aspect, and / or a hot melt adhesive prepared by the preparation method of the third aspect. The battery device of the embodiments of this application has the same advantages as the battery cell of the first aspect, and / or has the same advantages as the hot melt adhesive of the second aspect, and / or has the same advantages as the hot melt adhesive prepared by the preparation method of the third aspect.

[0067] The fifth aspect of this application also includes an electrical device comprising a battery cell of the first aspect, and / or a hot melt adhesive of the second aspect, and / or a hot melt adhesive prepared by the preparation method of the third aspect, and / or a battery device of the fourth aspect. The electrical device of the embodiments of this application has the same advantages as the battery cell of the first aspect, and / or has the same advantages as the hot melt adhesive of the second aspect, and / or has the same advantages as the hot melt adhesive prepared by the preparation method of the third aspect, and / or has the same advantages as the battery device of the fourth aspect.

[0068] The battery cells disclosed in this application can be used in electrical devices as power sources or in various energy storage systems that use battery cells as energy storage elements. Electrical devices can be, but are not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0069] For ease of explanation, the following embodiments will be described using a vehicle 1000 as an example of an electrical device according to an embodiment of this application.

[0070] Please refer to Figure 1 , Figure 1This is a schematic diagram of the structure of a vehicle 1000 provided in some embodiments of this application. The vehicle 1000 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A battery device 100 is provided inside the vehicle 1000, and the battery device 100 can be located at the bottom, front, or rear of the vehicle 1000. The battery device 100 can be used to power the vehicle 1000; for example, the battery device 100 can serve as the operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery device 100 to supply power to the motor 300, for example, to meet the power needs of the vehicle 1000 during starting, navigation, and driving.

[0071] In some embodiments of this application, the battery device 100 can not only serve as the operating power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0072] Please refer to Figure 2 , Figure 2 This is an exploded structural diagram of a battery device 100 provided in some embodiments of this application. The battery device 100 includes a housing 10 and a battery cell 20, with the battery cell 20 housed within the housing 10. The housing 10 provides a space for the battery cell 20 and can have various structures. In some embodiments, the housing 10 may include a first portion 11 and a second portion 12, which overlap each other, jointly defining a space for accommodating the battery cell 20. The second portion 12 may be a hollow structure with one open end, and the first portion 11 may be a plate-like structure, covering the open side of the second portion 12 so that the first portion 11 and the second portion 12 jointly define the space. Alternatively, the first portion 11 and the second portion 12 may both be hollow structures with one open side, with the open side of the first portion 11 covering the open side of the second portion 12. Of course, the housing 10 formed by the first portion 11 and the second portion 12 can have various shapes, such as a cylinder, a cuboid, etc.

[0073] In the battery device 100, there can be multiple battery cells 20. These multiple battery cells 20 can be connected in series, in parallel, or in a mixed configuration. A mixed configuration means that multiple battery cells 20 are connected in both series and parallel configurations. Multiple battery cells 20 can be directly connected in series, in parallel, or in a mixed configuration, and then the entire assembly of the multiple battery cells 20 is housed within the housing 10. Alternatively, the battery device 100 can also be composed of multiple battery cells 20 first connected in series, in parallel, or in a mixed configuration to form a battery module, and then multiple battery modules are connected in series, in parallel, or in a mixed configuration to form a whole, which is then housed within the housing 10.

[0074] The battery cell 20 can be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited to these. The battery cell 20 can be cylindrical, flat, cuboid, or other shapes.

[0075] Please refer to Figure 3 , Figure 3 This is an exploded structural diagram of a battery cell 20 provided in some embodiments of this application. The battery cell 20 refers to the smallest unit constituting the battery device 100. For example... Figure 3 The battery cell 20 includes a main housing 211, an electrode assembly 23, and an adapter plate 24.

[0076] like Figures 3-5 As shown, the main housing 211 includes a main housing 211 and an end cap 213. The end cap 213 is a component that covers the opening of the main housing 211 to isolate the internal environment of the battery cell 20 from the external environment. The shape of the end cap 213 can be adapted to the shape of the main housing 211 to fit the main housing 211. Optionally, the end cap 213 can be made of a material with a certain hardness and strength (such as aluminum alloy), so that the end cap 213 is less prone to deformation under pressure and impact, enabling the battery cell 20 to have higher structural strength and improved safety performance. The end cap 213 is provided with functional components such as terminals 212. An adapter piece 24 is used to connect the terminals 212 and the electrode assembly 23, so that the terminals 212 can be electrically connected to the electrode assembly 23 to output or input electrical energy from the battery cell 20. In this embodiment, there are two electrode posts 212 and two adapter pieces 24. Each adapter piece 24 is electrically connected to one electrode post 212. The adapter piece 24 has a protrusion 241 on the side facing the electrode post and a corresponding recess structure on the other side away from the electrode post. The adapter piece 24 is laser-welded to the end cap 213 at the bottom of the recess structure, forming a welding area 25. After the adapter piece 24 is welded to the end cap 213, welding slag and other particles are easily generated. Hot melt adhesive is applied to the welding area 25 and its surroundings, for example, in the welding area 25 and the recess structure of the adapter piece 24, forming a protective layer 26. This allows the protective layer 26 to fix the welding slag and other particles generated after welding onto the adapter piece 24, reducing the probability of these particles reaching the electrode assembly 23.

[0077] In some embodiments, the end cap 213 may also be provided with a pressure relief mechanism 214 (safety valve) for releasing internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold. For example, the pressure relief mechanism 214 may be a temperature-sensitive valve, a pressure-sensitive valve, etc. The end cap 213 may also be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this application embodiment does not impose any special limitations on this. In some embodiments, an insulating member may also be provided on the inner side of the end cap 213. The insulating member may be used to isolate the electrical connection components in the main housing 211 from the end cap 213 to reduce the risk of short circuit. For example, the insulating member may be plastic, rubber, etc. In some embodiments, a sealing member 27 may also be provided between the end cap 213 and the terminal post 212 to improve the sealing performance of the battery cell 20 and reduce the probability of leakage of the battery cell 20.

[0078] The main housing 211 is a component used to cooperate with the end cap 213 to form the internal environment of the battery cell 20. This internal environment can accommodate the electrode assembly 23, electrolyte, and other components. The main housing 211 and the end cap 213 can be independent components. An opening can be provided on the main housing 211, and the end cap 213 can be closed over the opening to form the internal environment of the battery cell 20. Alternatively, the end cap 213 and the main housing 211 can be integrated. Specifically, the end cap 213 and the main housing 211 can form a common connecting surface before other components are installed. When it is necessary to encapsulate the interior of the main housing 211, the end cap 213 closes the main housing 211. The main housing 211 can have various shapes and sizes, such as cuboid, cylindrical, or hexagonal prism. Specifically, the shape of the main housing 211 can be determined according to the specific shape and size of the electrode assembly 23. The main housing 211 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. This application embodiment does not impose any special restrictions on this.

[0079] Electrode assembly 23 is the component in the battery cell 20 where the electrochemical reaction occurs. The main casing 211 may contain one or more electrode assemblies 23. The electrode assembly 23 is mainly formed by winding or stacking positive and negative electrode sheets, and typically a separator is provided between the positive and negative electrode sheets. The portions of the positive and negative electrode sheets containing active material constitute the main body of the cell assembly, while the portions of the positive and negative electrode sheets without active material each constitute a tab 231. The positive and negative tabs may be located together at one end of the main body or separately at both ends of the main body. During the charging and discharging process of the battery device 100, the positive and negative active materials react with the electrolyte, and the tabs 231 connect to the terminals to form a current loop.

[0080] During use, the battery cells 20 of the battery device 100 generate a large amount of heat, which significantly reduces the service life of the battery device 100. A heat dissipation structure (not shown) is provided in the battery device 100 to cool and dissipate heat from the battery cells 20, providing a suitable temperature for stable operation of the battery cells 20. In this embodiment, the heat dissipation structure is disposed inside the housing 10.

[0081] [Positive electrode plate]

[0082] In some embodiments, the positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector.

[0083] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0084] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0085] In some embodiments, the positive electrode film layer includes a positive electrode active material. When the secondary battery is a lithium-ion battery, the positive electrode active material can be a positive electrode active material known in the art for lithium-ion batteries. As an example, the positive electrode active material may include at least one of the following materials: lithium phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM)523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 ), LiN i0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Examples of lithium phosphates with an olivine structure include, but are not limited to, lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0086] In some embodiments, the positive electrode film layer may optionally include a binder. The binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0087] In some embodiments, the positive electrode film may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0088] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, second binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0089] [Negative electrode plate]

[0090] The negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector, the negative electrode film layer including a negative electrode active material.

[0091] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0092] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0093] In some embodiments, the negative electrode active material may be a negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0094] In some embodiments, the negative electrode film layer may optionally include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0095] In some embodiments, the negative electrode film may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0096] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0097] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0098] [Isolation membrane]

[0099] This application does not impose any particular restrictions on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected.

[0100] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0101] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into a battery cell assembly using a winding or stacking process.

[0102] In some implementations, the housing can be a rigid housing, such as a hard plastic housing, an aluminum housing, a steel housing, etc.

[0103] This application does not impose any particular restrictions on the shape of the battery cell; it can be cylindrical, square, or any other arbitrary shape.

[0104] The beneficial effects of this application are further illustrated below with reference to the embodiments.

[0105] To make the technical problems, technical solutions, and beneficial effects solved by the embodiments of this application clearer, the following will provide a more detailed description in conjunction with the embodiments and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its applications. Based on the embodiments in this application, those skilled in the art can make reasonable judgments without creative effort.

[0106] All other embodiments obtained are within the scope of protection of this application.

[0107] Example 1

[0108] 1) Preparation of hot melt adhesive

[0109] Raw material preparation: maleic anhydride modified polyethylene (Mitsui Chemicals NE072E), atactic polypropylene (Dow Chemicals GA1900), terpene phenol resin (Japan Yasuhara Chemicals P105), carbodiimide (Tianjin Lialon 1010). Weigh the corresponding raw materials according to the component ratio.

[0110] The hot melt adhesive obtained in this embodiment contains the following chemical components by weight: maleic anhydride modified polyethylene, 35 parts; atactic polypropylene, 38 parts; terpene phenol resin, 25 parts; and carbodiimide, 0.2 parts. The above materials are added to a reaction vessel, the temperature of which is raised to 150°C, and the vessel is heated and stirred under vacuum at 100 rpm for 10 minutes. Once completely mixed into a uniform and clear liquid, the mixture is filtered and then cooled to obtain the hot melt adhesive.

[0111] 2) Preparation of battery cells

[0112] 2.1) Production of the positive electrode sheet

[0113] Lithium nickel cobalt manganese oxide (NCM631): conductive carbon black: PVDF = 8:1:1 by mass, then N-methylpyrrolidone solvent is added. This mixture is coated on both sides of an aluminum foil, cold-pressed, and cut to obtain a positive electrode sheet. The positive electrode sheet is then rolled into a film roll, and a ceramic slurry is sprayed onto the cut surfaces of the film roll. In the ceramic slurry, the ceramic material is boehmite (39 wt%), the binder is polyacrylate (5 wt%), the solvent is N-methylpyrrolidone, the solid content of the slurry is 10%, and the viscosity of the slurry is 800 mPa·s.

[0114] 2.2) Preparation of negative electrode sheet

[0115] Artificial graphite, conductive carbon black, carboxymethyl cellulose (CMC) binder, and water solvent are uniformly mixed in a weight ratio of 95:2:3:100, coated on both sides of copper foil, and then cold-pressed and cut to obtain the negative electrode sheet.

[0116] 2.3) Preparation of the diaphragm

[0117] A polyethylene film with a thickness of 10 μm was used as the separator.

[0118] 2.4) Preparation of electrolyte:

[0119] Ethylene carbonate, diethyl carbonate, and dimethyl carbonate were mixed in a volume ratio of 1:1:1. LiPF6 was then dissolved in this solution to obtain the electrolyte. The concentration of LiPF6 in the electrolyte was 1 mol / L.

[0120] 2.5) Assembly of individual battery cells:

[0121] The electrodes are arranged in the order of "separator-negative electrode-separator-positive electrode". One end of the positive electrode, negative electrode, and two separators is fixed to the discharge roller, and the other end is stacked together and fixed to the winding shaft. The winding shaft is rotated by a motor to wind the positive electrode, negative electrode, and two separators to obtain a wound battery assembly.

[0122] The end cap and the adapter are laser welded together, and the hot melt adhesive described above is applied to the welding area and the area around the welding area.

[0123] The wound battery assembly is placed inside the housing, the end cap is closed on the housing, and electrolyte is injected to form a battery cell.

[0124] For details of the process and performance parameters of other embodiments and comparative examples of this application, please refer to Table 1. The rest are the same as those of Embodiment 1.

[0125] Examples 2 to 5

[0126] The proportions of maleic anhydride-modified polyethylene were varied to 50 parts, 40 parts, 30 parts, and 20 parts, respectively. Other aspects were similar to those in Example 1 and will not be repeated here.

[0127] Examples 6 to 9

[0128] The proportions of atactic polypropylene and the mixing temperature were varied, as detailed in Table 2. Other aspects are similar to those in Example 1 and will not be repeated here.

[0129] Examples 10-12

[0130] The proportions of terpene phenol resin were varied to 15 parts, 35 parts, and 40 parts, respectively. Other aspects were similar to those in Example 1 and will not be repeated here.

[0131] Examples 13-15

[0132] The grafting rates of maleic anhydride-modified polyethylene were changed to 1%, 3%, and 4%, respectively. Other aspects were similar to those in Example 1 and will not be repeated here.

[0133] Examples 16-18

[0134] The raw materials prepared are: maleic anhydride modified polyethylene (Idemitsu, Japan), random polypropylene (Dow Chemical), terpene phenol resin (Yasuhara Chemical, Japan), and carbodiimide (Tianjin Lialon). Other process parameters are detailed in Table 2.

[0135] Comparative Example 1

[0136] Excluding 1) the preparation of the hot melt adhesive; 2.5) the application of the hot melt adhesive to the welding area and around the welding area during the assembly of the battery cells. Other aspects are similar to those in Example 1 and will not be repeated here.

[0137] Comparative Example 2

[0138] Compared to the example, the preparation of the hot melt adhesive is not included in 1). The hot melt adhesive used is SBS hot melt adhesive, which comprises 70 parts by weight of styrene-butadiene copolymer (Henkel, model 1573E), 29.5 parts by weight of styrene-isoprene-styrene (Kerteng Polymer Co., Ltd.), and 0.5 parts by weight of 2,6-di-tert-butyl-p-cresol (Tianjin Lianlong New Material Co., Ltd.) antioxidant. Other aspects are similar to those in Example 1 and will not be repeated here.

[0139] The performance parameter testing methods for Examples 1-18 and Comparative Examples 1-2 of this application are as follows:

[0140] 1) Adhesion test.

[0141] Load the hot melt adhesive block into the hot melt dispensing machine. Take copper and aluminum sheets of a certain size (length * width * thickness 150 * 30 * 5 mm). Apply the adhesive evenly to the surface of the copper and aluminum sheets, with a coating size of 80 * 10 mm (length * width) and a thickness between 0.5 and 5.0 mm. After cooling, gently tear off the head and bend it in the opposite direction at a bending angle of 180°. Use a high-speed rail tensile testing machine to test. Fix one end of the copper or aluminum sheet to the lower clamp of the tensile testing machine, and fix the bent end of the sample to the upper clamp. Adjust the sample angle to ensure that the upper and lower ends are in a vertical position. Then stretch the sample at a speed of 50 mm / min until the hot melt adhesive is completely peeled off from the copper or aluminum sheet. Record the displacement and force during the process. Generally, the force at which the forces are balanced is considered to be the adhesive force of the hot melt adhesive.

[0142] The adhesion of the samples was tested before and after immersion in the electrolyte for different times. The electrolyte consisted of ethylene carbonate (EC), methyl ethyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio of 1:1:1, with a LiPF6 concentration of 1 mol / L.

[0143] 2) Number-average molecular weight test.

[0144] The number-average molecular weight of the samples was determined by gel permeation chromatography (GPC).

[0145] 3) Grafting rate test.

[0146] The infrared spectrum of hot melt adhesive was tested using an IS10 Fourier transform infrared spectrometer from Nicolet Corporation, USA, in accordance with the general rules of infrared spectroscopy analysis method in GB / T6040-2002.

[0147] 4) Voltage test

[0148] The individual battery cells were stored at 60°C for 200 days, and their voltages were tested using a 6.5-digit multimeter. The multimeter's selector switch was set to the DC voltage (DCV) measurement range. The red probe of the multimeter was connected to the positive terminal of the battery cell, and the black probe to the negative terminal. The voltage value displayed on the multimeter was then read.

[0149] 5) Battery capacity test

[0150] Battery capacity test: After resting for 30 minutes, discharge at a constant current of 0.33C to 2.5V; after resting for 30 minutes, charge at a constant current of 0.33C to 4.25V, charge at a constant voltage of 4.25V to a current of 0.05C, and rest for 30 minutes; discharge at a constant current of 0.33C to 2.5V, and discharge at a constant voltage of 2.5V to a current of 0.05C. Obtain this discharge capacity C0.

[0151] Adjust SOC before storage: Let stand for 30 minutes, discharge at 0.33C constant current to 2.5V; let stand for 5 minutes, charge at 0.33C constant current to 4.25V, charge at 4.25V constant voltage capacity to 0.05C current, let stand for 30 minutes; discharge at 0.33C to 0.05C current (adjust SOC to 100%), let stand for 30 minutes;

[0152] The battery was stored at 60±2℃ for 200 days. The battery capacity test was repeated to obtain the discharge capacity as C1 and the storage capacity decay as 1-C1 / C0.

[0153]

[0154]

[0155] The hot melt adhesive from Example 1 was made into thicknesses of 0.5 mm, 1.0 mm, 2.0 mm, 3.0 mm, and 5.0 mm, respectively, and applied to copper and aluminum sheets. The initial adhesion and the adhesion after immersion in electrolyte for 7, 15, 30, 60, and 90 days were tested. As can be seen from Table 1, the hot melt adhesive of Example 1 of the present invention still has high adhesion even when made into different thicknesses and immersed in electrolyte for 90 days.

[0156] As shown in Table 2, Comparative Example 1 did not apply hot melt adhesive to the welding area, while Comparative Example 2 applied styrene-butadiene copolymer hot melt adhesive to the welding area. Examples 1-18 of this application showed higher adhesion after 90 days of immersion compared to applications using the hot melt adhesive of this application in the welding area. The styrene-butadiene copolymer of Comparative Example 2, when applied as a hot melt adhesive to the welding area, was prone to swelling, resulting in lower adhesion after 90 days of immersion in the electrolyte, and significant capacity decay in the battery cells after 200 days of storage at 60°C. Compared to Comparative Examples 1 and 2, Examples 1-18 of this application showed higher voltage and less capacity decay after 200 days of storage at 60°C, indicating that applying the hot melt adhesive of this application can reduce the amount of welding slag and other particles reaching the battery cells, thus reducing self-discharge caused by welding slag shedding from the battery cells.

[0157] The above are merely embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A battery cell, characterized in that, Includes hot melt adhesive, which contains the following chemical components in parts by weight: Maleic anhydride modified polyethylene, 20 parts to 50 parts; Random polypropylene, 20 to 50 parts; 15 to 40 parts of terpene phenol resin; Antioxidant, 0.1 to 1 part.

2. The battery cell according to claim 1, characterized in that, The hot melt adhesive contains the following chemical components in parts by weight: Maleic anhydride modified polyethylene, 35 parts to 45 parts; Random polypropylene, 35 to 45 parts; Terpene phenol resin, 15 to 25 parts; Antioxidant, 0.2 to 0.8 parts.

3. The battery cell according to claim 1 or 2, characterized in that, Based on the total mass of the hot melt adhesive, the mass percentage of the atactic polypropylene is 20% to 50%.

4. The battery cell according to any one of claims 1 to 3, characterized in that, The maleic anhydride-modified polyethylene has a number-average molecular weight of 10,000 to 100,000. The number-average molecular weight of the atactic polypropylene is 10,000 to 100,000. The number-average molecular weight of the terpene phenol resin is 500 to 2000.

5. The battery cell according to any one of claims 1 to 4, characterized in that, The antioxidants include one or more of carbodiimide, hindered phenol, butylphenol, and butylphenol derivatives.

6. The battery cell according to any one of claims 1 to 5, characterized in that, In the maleic anhydride-modified polyethylene, the grafting rate of maleic anhydride onto polyethylene is 2% to 4%.

7. The battery cell according to any one of claims 1 to 6, characterized in that, The battery cell includes: A housing, wherein the housing is provided with an accommodating space, and an electrode post is provided on the housing; An electrode assembly disposed within the accommodating space and having at least one electrode tab; An adapter plate electrically connects the tab and the post. The adapter plate and the post are connected by welding, and a welding area is formed on the side of the adapter plate away from the post. The hot melt adhesive covers the welding area to form a protective layer.

8. The battery cell according to any one of claims 1 to 7, characterized in that, The thickness of the protective layer is 0.5mm to 5mm.

9. The battery cell according to any one of claims 1 to 8, characterized in that, The battery cell includes an electrolyte, the electrolyte includes a solvent, and the solvent includes an ester solvent.

10. A hot melt adhesive, characterized in that, The hot melt adhesive contains the following chemical components in parts by weight: Maleic anhydride modified polyethylene, 20 parts to 50 parts; Random polypropylene, 20 to 50 parts; 15 to 40 parts of terpene phenol resin; Antioxidant, 0.1 to 1 part.

11. The hot melt adhesive according to claim 10, characterized in that, The adhesion strength of hot melt adhesive to metal materials after soaking in electrolyte for 90 days is 529 N / m to 565 N / m.

12. A method for preparing a hot melt adhesive, characterized in that, include: Mix 20-50 parts by weight of maleic anhydride modified polyethylene, 20-50 parts by weight of atactic polypropylene, 15-40 parts by weight of terpene phenol resin, and 0.1-1.0 parts by weight of antioxidant, and stir at 150℃-180℃ to obtain hot melt adhesive.

13. The method for preparing hot melt adhesive according to claim 12, characterized in that, The stirring speed is 100 rpm to 300 rpm; and / or the stirring time is 10 min to 30 min; the stirring atmosphere is a vacuum.

14. A battery device, characterized in that, Includes the battery cell according to any one of claims 1 to 9, and / or the hot melt adhesive according to claim 10 or 11, and / or the hot melt adhesive prepared by the preparation method according to claim 12 or 13.

15. An electrical appliance, characterized in that, Includes the battery cell according to any one of claims 1 to 9, and / or the hot melt adhesive according to claim 10 or 11, and / or the hot melt adhesive prepared by the preparation method according to claim 12 or 13, and / or the battery device according to claim 14.

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