Electrolyte, battery, and upper cover assembly

Abstract

Provided are an electrolyte, a battery, and an upper cover assembly. The electrolyte includes at least one solvent having a vaporization temperature of the decomposition temperature of an SEI film or below. A battery comprising the electrolyte is a high-safety battery, which can avoid the possibility of thermal runaway of the battery, and fundamentally solves the safety problem of the battery.

Description

An electrolyte, a battery, and a cover assembly Technical Field

[0001] This application belongs to the field of battery technology, specifically relating to an electrolyte, a battery, and a cover assembly. Background Technology

[0002] As a highly efficient and portable energy storage device, batteries have a wide range of applications, mainly in electric vehicles, energy storage equipment, aerospace and other fields.

[0003] In recent years, with the further development of batteries, the safe use of batteries has also attracted attention. Under the influence of factors such as overcharging, over-discharging, overheating, and mechanical impact, battery separators are prone to collapse and internal short circuits, which can lead to thermal runaway and create safety hazards.

[0004] Thermal runaway is essentially a chain reaction. In its later stages, large amounts of heat, flammable gases, and internal battery chemicals are released through ejection or leakage, leading to serious safety incidents. Therefore, effectively blocking the thermal runaway process from the outset and preventing it from escalating further is the core and key to solving battery safety issues. Summary of the Invention

[0005] This application provides an electrolyte, a battery, and a cover assembly. This battery is a safe battery that fundamentally solves the problem of thermal runaway in batteries.

[0006] The first aspect of this application provides an electrolyte and a battery having the electrolyte. The battery having the electrolyte is a highly safe battery that can avoid the possibility of thermal runaway and fundamentally solve the battery safety problem.

[0007] The electrolyte provided in the first aspect of this application includes at least one solvent with a vaporization temperature below the SEI film decomposition temperature, and the solvent with a vaporization temperature below the SEI film decomposition temperature has a mass percentage content of 10% or more in the electrolyte.

[0008] Furthermore, the percentage content of solvents with vaporization temperatures below the SEI film decomposition temperature in the electrolyte is above 20%.

[0009] Furthermore, the percentage content of solvents with vaporization temperatures below the SEI film decomposition temperature in the electrolyte is above 30%.

[0010] Furthermore, the electrolyte includes at least one solvent with a vaporization temperature below 90°C.

[0011] Furthermore, the electrolyte includes at least one solvent with a vaporization temperature below 75°C.

[0012] Furthermore, solvents with a vaporization temperature below 75°C include methyl formate, ethyl formate, methyl acetate, tetrahydrofuran, dioxolane, and ethyl trifluoroacetate.

[0013] Furthermore, solvents with a vaporization temperature below 75°C include dioxolane.

[0014] The first aspect of this application also provides a battery having the above-mentioned electrolyte.

[0015] The second aspect of this application provides a battery and a cover assembly, the battery and the battery having the cover assembly being a safe battery capable of effectively blocking the thermal runaway process from the front end and preventing the thermal runaway problem from further aggravating.

[0016] The battery provided in the second aspect of this application includes a casing and an electrode assembly; the improvement is that: a heat dissipation cavity communicating with the inner cavity of the battery is provided on the casing; after the battery is heated, the electrolyte vaporizes into electrolyte vapor and enters the heat dissipation cavity, and the heat dissipation cavity condenses the electrolyte vapor into liquid and then returns it to the battery casing.

[0017] This application adds a heat dissipation cavity to the battery casing. During battery operation, if the temperature rises, the free electrolyte in the electrolyte can quickly absorb heat and vaporize. The generated electrolyte vapor enters the heat dissipation cavity, which condenses the electrolyte vapor into liquid and then flows back into the battery casing. The electrolyte absorbs heat, evaporates, vaporizes, condenses, and flows back in this way, which not only keeps the battery inside at a critical temperature and effectively prevents overheating, but also increases the volume of the battery casing cavity by the heat dissipation cavity, improving the pressure resistance. This effectively blocks the thermal runaway process from the front end, prevents further aggravation of thermal runaway, and improves battery safety.

[0018] Furthermore, the battery of this application has an electrode assembly accommodating area and an electrolyte storage area; the electrolyte storage cavity stores a large amount of free electrolyte, which not only ensures that there is enough electrolyte in the battery to cool the battery, but also allows the electrolyte consumed in the battery to be replenished in time, avoiding local drying, ensuring stable internal reactions of the battery, and improving charge and discharge performance.

[0019] This application provides the following three forms of electrolyte storage area and electrode assembly housing area:

[0020] The first method involves dividing the battery into an electrolyte storage area and an electrode assembly receiving area using a separator. Specifically, the separator is installed inside the casing to separate the electrolyte storage area for storing free electrolyte and the electrode assembly receiving area for placing at least one electrode assembly. The separator is provided with at least one channel for connecting the electrolyte storage area and the electrode assembly receiving area, and at least one side wall or bottom of the electrode assembly is attached to the first separator.

[0021] The second method involves providing multiple ribs on the inner surface of at least one side wall of the casing, with each rib forming an electrolyte storage area. Compared to the first method, the electrolyte storage areas are more dispersed in this arrangement.

[0022] The third type has multiple separators and two or more electrode assemblies. In each electrode assembly, the positive tabs are connected in parallel and electrically connected to the positive terminal of the battery, and in each electrode assembly, the negative tabs are connected in parallel and electrically connected to the negative terminal of the battery. The space between the two separators forms an electrode assembly receiving area. The surface of each separator that contacts the electrode assembly is provided with multiple ribs. The space between each rib forms an electrolyte storage area, and the separator is provided with a channel connecting the adjacent electrode assembly receiving areas.

[0023] Furthermore, in order to facilitate processing, reduce costs, and avoid the problem of poor pressure resistance caused by weak areas in the battery casing, and to ensure that the condensed electrolyte can quickly flow back into the battery, the heat dissipation cavity is integrally formed on the top of the casing, and the thickness of the heat dissipation cavity is the same as the thickness of the casing.

[0024] To further improve the condensation effect on electrolyte vapor, this application provides the following optimizations and improvements, one or more of which can be selected:

[0025] The first type: The outer surface of the heat dissipation cavity is provided with heat dissipation fins.

[0026] The second type: a semiconductor cooling chip is provided on the outer surface of the heat dissipation cavity.

[0027] The third type: The heat dissipation cavity is equipped with a liquid cooling channel.

[0028] Furthermore, the vaporization temperature of the electrolyte is lower than the decomposition temperature of the SEI membrane; or, the vaporization temperature of the electrolyte is lower than the decomposition temperature of the membrane.

[0029] The second aspect of this application also provides a top cover assembly for a battery, including a top cover plate, a positive terminal, a negative terminal, and a heat dissipation cavity; the positive terminal and the negative terminal are insulated and sealed to the top cover plate; the heat dissipation cavity is integrally formed on the top cover plate and located between the positive terminal and the negative terminal, and is used to condense the electrolyte vapor into liquid and return it to the battery casing after the battery is heated.

[0030] Furthermore, at least one of the inner or outer surfaces of the heat dissipation cavity is provided with heat dissipation fins, or at least one side wall of the heat dissipation cavity is provided with a liquid cooling channel.

[0031] Compared with the prior art, the advantages of the technical solution of this application are as follows:

[0032] 1. The electrolyte provided in this application contains a solvent with a vaporization temperature below the SEI film decomposition temperature. During use, batteries containing this electrolyte, due to the presence of a solvent with a vaporization temperature below the SEI film decomposition temperature, can absorb heat from the battery's interior before the internal temperature reaches the SEI film decomposition temperature, vaporizing from liquid to gas. The vaporized electrolyte then contacts the battery casing, which absorbs heat, condensing the vaporized electrolyte back into liquid and flowing back into the battery casing. This cycle repeats, ensuring that the temperature of the electrode components and electrolyte within the battery remains below the SEI film decomposition temperature, thus preventing the possibility of thermal runaway and fundamentally solving the battery safety problem. Simultaneously, at this temperature, the electrode components and electrolyte do not undergo decomposition reactions, and the electrolyte and electrode components do not decompose to produce large amounts of gas, thus avoiding problems such as battery casing rupture due to excessive internal pressure. Furthermore, since no gas escapes from the battery casing, battery safety is further enhanced.

[0033] 2. In the electrolyte provided in this application, the percentage content of solvents with a vaporization temperature below the SEI film decomposition temperature is more than 20%, which enables the electrolyte to fully absorb the heat inside the battery and quickly process the heat inside the battery, further reducing the possibility of thermal runaway.

[0034] 3. The electrolyte provided in this application includes at least one solvent with a vaporization temperature below 90°C. At this temperature, the electrode assembly and the electrolyte will not undergo decomposition or other reactions, thus avoiding the possibility of thermal runaway of the battery. Furthermore, the electrolyte includes at least one solvent with a vaporization temperature below 75°C, so that the temperature of the electrode assembly and the electrolyte will not exceed 75°C, further reducing the possibility of SEI film decomposition, and thus further reducing the possibility of thermal runaway of the battery.

[0035] 4. The electrolyte provided in this application uses a solvent with a vaporization temperature below the SEI film decomposition temperature and a large specific heat capacity, so as to absorb more heat during the vaporization process of the electrolyte, so that the heat inside the battery can be quickly carried away by the electrolyte, avoiding thermal runaway of the battery and further improving the safety of the battery during use.

[0036] 5. This application also provides a battery containing the above-mentioned electrolyte. The battery containing the above-mentioned electrolyte avoids the possibility of thermal runaway during use and has high safety. Attached Figure Description

[0037] Figure 1 is a schematic diagram of the external shape of the battery in Examples 3 to 5;

[0038] Figure 2 is a horizontal cross-sectional view of the battery in Example 3;

[0039] Figure 3 is a schematic diagram of the upper cover assembly in Embodiments 3 to 5;

[0040] Figure 4 is a horizontal cross-sectional view of the battery in Example 4;

[0041] Figure 5 is a horizontal cross-sectional view of the battery in Example 5;

[0042] Figure 6 is a structural diagram of the heat dissipation cavity of the battery in Example 6 with heat dissipation fins;

[0043] Figure 7 is a structural diagram of the liquid cooling channel provided on the heat dissipation cavity of the battery in Example 6.

[0044] Reference numerals: 100-Battery; 1-Upper cover assembly, 11-Upper cover plate, 12-Positive electrode post, 13-Negative electrode post, 14-Heat dissipation cavity, 141-Heat dissipation fins, 142-Liquid cooling channel, 15-Rib, 2-Cylinder body, 3-Lower cover plate, 4-Electrode assembly, 5-Separator, 6-Electrolyte storage area, 7-Electrode assembly housing area. Detailed Implementation

[0045] The technical solutions in the embodiments of this application will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0046] The phrase "in some embodiments" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments. In the description of this application, "a plurality of" means two or more, unless otherwise expressly and specifically defined.

[0047] In this specification, unless otherwise expressly specified and limited, the term "connection" should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral connection; it can refer to a direct connection, an indirect connection via an intermediate component, or a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0048] Furthermore, it should be noted in the description of this application that the orientation or positional relationship indicated by terms such as "top," "bottom," "inner," and "outer" is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this application and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0049] The electrolyte in existing batteries is typically composed of lithium salts, solvents, and additives, with the solvent usually accounting for 80% to 85% of the total mass.

[0050] When an internal short circuit or heat accumulation occurs in a battery, the internal temperature reaches approximately 90–120°C. At this point, thermal runaway occurs, the SEI film decomposes, releasing heat and producing gases such as C2H4, CO2, and O2. As the internal temperature continues to rise, the negative and positive electrode materials begin to decompose and react with the electrolyte to produce a large amount of gas. Simultaneously, the electrolyte and electrolyte themselves undergo a series of decomposition reactions, generating a large amount of gas. This large amount of gas increases the pressure inside the battery casing, causing the battery casing to expand and rupture. A large amount of high-temperature, high-pressure material is ejected from the battery casing, creating a safety hazard.

[0051] Based on this, this application provides a safe battery that fundamentally solves the problem of thermal runaway through corresponding optimization measures. The specific optimization measures are as follows: First, the electrolyte of the battery is optimized; second, the battery casing is optimized.

[0052] The first aspect of this application provides an electrolyte and a battery having the electrolyte, wherein the battery having the electrolyte is a safe battery. The electrolyte includes at least one solvent with a vaporization temperature below the SEI film decomposition temperature, and the mass percentage of the solvent with a vaporization temperature below the SEI film decomposition temperature in the electrolyte is 10% or more. During use, the internal temperature of the battery with this electrolyte remains below the SEI film decomposition temperature, preventing heat accumulation and the generation of large amounts of gas, thus eliminating the possibility of thermal runaway at the source.

[0053] The electrolyte provided in this application includes at least one solvent with a vaporization temperature below 90°C, and the mass percentage of this solvent in the electrolyte is 10% or more. That is, the SEI film decomposition temperature can be 90°C. At this temperature, the electrode assembly and electrolyte will not undergo decomposition or other reactions, thus avoiding the possibility of thermal runaway of the battery. Furthermore, the electrolyte includes at least one solvent with a vaporization temperature below 75°C, so that the temperature of the electrode assembly and electrolyte will not exceed 75°C, further reducing the possibility of SEI film decomposition, and thus further reducing the possibility of thermal runaway of the battery.

[0054] During use, batteries with this electrolyte contain solvents with a vaporization temperature below 90°C. Therefore, before the internal temperature reaches 90°C, a portion of the electrolyte absorbs heat from the battery's interior, vaporizing from liquid to gas. Upon contact with the battery casing, the casing absorbs heat, condensing the vaporized electrolyte back into liquid and flowing back into the casing. This cycle repeats, ensuring that the temperature of the electrode components and electrolyte inside the battery remains below 90°C. Because the temperature of the electrode components and electrolyte remains below 90°C, decomposition reactions do not occur, thus preventing the possibility of thermal runaway and fundamentally solving the battery safety problem. Furthermore, since the temperature of the electrode components and electrolyte remains below 90°C, decomposition reactions do not occur, preventing the generation of large amounts of gas. This avoids problems such as the battery casing rupture due to excessive internal pressure. Additionally, the absence of gas venting from the battery casing further enhances battery safety.

[0055] Example 1

[0056] This embodiment provides an electrolyte comprising at least one solvent with a vaporization temperature below 90°C, wherein the solvent with a vaporization temperature below 90°C constitutes more than 10% by mass in the electrolyte. The portion of the solvent in this electrolyte has a vaporization temperature below 90°C, meaning that a portion of the solvent in the electrolyte has a boiling point below 90°C. This portion of the solvent with a vaporization temperature below 90°C can absorb heat and vaporize at temperatures below 90°C, and can also liquefy after heat exchange with the battery casing.

[0057] After the electrolyte is filled into the battery casing, in the event of an internal short circuit or heat accumulation, before the internal temperature of the battery reaches the SEI film decomposition temperature (90°C), some of the electrolyte absorbs heat from the battery and vaporizes. The vaporized electrolyte then contacts the battery casing, exchanges heat with it, and liquefies. The liquefied electrolyte flows back into the battery, continuing to absorb heat generated inside, ensuring that the highest internal temperature of the battery remains below the decomposition temperature of the SEI film in the electrode assembly, thus preventing the possibility of thermal runaway. Simultaneously, because the electrode assembly and electrolyte do not decompose, the amount of gas inside the battery is relatively small, avoiding problems such as battery casing rupture due to excessive gas and internal pressure. Furthermore, since no gas escapes, the battery safety issue is fundamentally resolved.

[0058] In this embodiment, solvents with a vaporization temperature below 90°C include dimethyl carbonate (DMC), methyl formate (MF), ethyl formate (EF), methyl acetate (MA), ethyl acetate (EA), tetrahydrofuran (THF), 2-methyltetrahydrofuran (2Me-THF), dioxolane (DOL), 1,2-dimethoxyethane (DME), acetonitrile (AN), ethyl difluoroacetate (EDFA), ethyl trifluoroacetate (ETFA), methyl propionate (MP), fluorobenzene (FB), butyl acetate (PB), dimethoxymethane (DMM), and 1,2-dimethoxypropane (DMP). Their specific boiling points are detailed in Table 1.

[0059] Meanwhile, in this embodiment, when selecting a solvent for the electrolyte, a solvent with a large specific heat capacity is chosen as much as possible. This maximizes the specific heat capacity of the electrolyte, allowing it to absorb more heat during the vaporization process. This enables the electrolyte to absorb more heat from inside the battery more quickly, thus preventing thermal runaway and further improving battery safety during use.

[0060] In this embodiment, the electrolyte includes dioxolane DOL. Dioxolane DOL has a large specific heat capacity. Electrolytes containing dioxolane DOL absorb more heat during vaporization and can absorb more heat from inside the battery more quickly.

[0061] The electrolyte in this embodiment may include one or more of the solvents mentioned above. If it includes only one solvent with a vaporization temperature below 90°C, then the mass percentage of that solvent in the electrolyte is 10% or more. If it includes multiple solvents with vaporization temperatures below 90°C, then the total mass percentage of the multiple solvents in the electrolyte is 10% or more.

[0062] In some embodiments, the solvent with a vaporization temperature below 90°C constitutes more than 20% of the electrolyte by mass, enabling the electrolyte to fully absorb heat from inside the battery and rapidly manage it, further reducing the possibility of thermal runaway. Ideally, without affecting electrolyte performance, the solvent with a vaporization temperature below 90°C constitutes more than 30% of the electrolyte by mass.

[0063] Table 1

[0064] Example 2

[0065] This embodiment provides a battery, which mainly consists of a battery casing, an electrode assembly located inside the battery casing, and an electrolyte. The electrolyte used is the electrolyte provided in Embodiment 1.

[0066] In this embodiment, before the internal temperature of the battery reaches the SEI film decomposition temperature (90°C) due to internal short circuit or heat accumulation, a portion of the electrolyte inside the battery casing absorbs heat from the electrode assembly and rapidly vaporizes, carrying away the internal heat. The vaporized electrolyte then contacts the battery casing, transferring heat to it. The battery casing absorbs the heat from the vaporized electrolyte, which condenses back into liquid and flows back into the battery. This cycle repeats continuously, keeping the maximum temperature of the electrode assembly and electrolyte below the SEI film decomposition temperature. Because the temperature of the electrode assembly and electrolyte remains below the SEI film decomposition temperature, decomposition and other reactions do not occur, thus avoiding the possibility of thermal runaway in the battery.

[0067] After absorbing heat from the electrode components, a portion of the electrolyte inside the battery casing vaporizes. The presence of gas inside the battery creates internal pressure. Therefore, the thickness of the battery casing must be sufficient to withstand this pressure. Furthermore, it's crucial to ensure that the vaporized electrolyte does not negatively impact the battery casing. Additionally, a heat dissipation device can be installed outside the battery casing to manage the heat and facilitate the rapid liquefaction of the vaporized electrolyte.

[0068] The battery provided in this embodiment is a high-safety lithium-ion battery. In this battery, the boiling point of some solvents in the electrolyte is below 90°C, ensuring that the temperature of the electrode components and electrolyte inside the battery remains below 90°C. At this temperature, the electrode components and electrolyte will not undergo decomposition or other reactions, thus avoiding the possibility of thermal runaway. Simultaneously, at this temperature, the electrode components and electrolyte will not decompose, preventing the release of large amounts of gases such as hydrogen, carbon monoxide, carbon dioxide, and methane. This avoids problems such as battery casing rupture due to excessive internal pressure caused by excessive gas. Furthermore, the battery casing in this embodiment has a certain pressure-bearing capacity, preventing rupture due to excessive pressure and gas leakage. Because there is no gas release, the safety issues following thermal runaway in existing lithium batteries are resolved, thus fundamentally solving the safety problem of battery leakage.

[0069] The second aspect of this application provides a battery and a cover assembly. The battery is a safe battery, and the basic design concept is as follows:

[0070] The battery casing is equipped with a heat dissipation cavity that communicates with the battery's internal cavity. Utilizing this heat dissipation cavity, when the battery heats up, the free electrolyte stored in the electrolyte storage cavity can rapidly absorb heat and vaporize. The generated electrolyte vapor enters the heat dissipation cavity, where it condenses back into liquid and flows back into the battery casing. This process of electrolyte absorbing heat, evaporating, vaporizing, condensing, and flowing back not only maintains the battery's internal temperature at a critical level, effectively preventing overheating, but also increases the internal volume of the battery casing by expanding the heat dissipation cavity, improving pressure resistance. This effectively blocks the thermal runaway process from the front end, preventing further escalation of thermal runaway and enhancing battery safety.

[0071] Based on this, this application further divides the battery casing into an electrode assembly accommodating area and an electrolyte storage area; the electrolyte storage area can store a large amount of free electrolyte in the battery. If the battery is found to be overheating, sufficient electrolyte can also improve the cooling effect of the battery. In addition, the electrolyte consumed during normal operation of the battery can be replenished in time to avoid local drying, ensure the stability of the internal reaction of the battery, and improve the charging and discharging performance.

[0072] Example 3

[0073] As shown in Figures 1 and 2, this embodiment provides a battery 100, including an upper cover assembly 1, a cylindrical body 2, a lower cover plate 3, and at least one electrode assembly 4; the upper cover assembly 1, the cylindrical body 2, and the lower cover plate 3 together form a shell.

[0074] As shown in Figure 2, in this embodiment, a partition 5 is provided inside the housing. The partition 5 divides the housing into an electrolyte storage area 6 for storing free electrolyte and an electrode assembly receiving area 7 for placing at least one electrode assembly. Each partition 5 is provided with at least one channel for connecting the electrolyte storage area and the electrode assembly receiving area.

[0075] In this embodiment, there can be one or more electrode components 4. If there is one electrode component 4, the positive and negative tabs of the electrode component are directly connected to the positive and negative terminals of the battery, respectively. If there are multiple electrode components 4, the positive tabs of each electrode component are connected to the positive terminal of the battery, and the negative tabs of each electrode component are connected to the negative terminal of the battery.

[0076] The channel can take several forms: one is that the perimeter of the partition has at least one notch; the other is that the partition has at least one through hole, the purpose of which is to ensure that the electrolyte storage area and the electrode assembly housing area are interconnected.

[0077] For ease of processing, in this embodiment, the cylinder 2 and the lower cover plate 3 are integrally formed by stamping and injection molding. Of course, in some other embodiments, the lower cover plate 3 and the cylinder 2 can also be connected together by welding.

[0078] In this embodiment, the electrolyte storage area 6 and the electrode assembly receiving area 7 are distributed along the width direction of the battery. In some other embodiments, the electrolyte storage area 6 and the electrode assembly receiving area 7 may also be distributed along the thickness direction and the height direction of the battery.

[0079] As shown in Figure 3, in this embodiment, the upper cover assembly 1 includes an upper cover plate 11, a positive terminal post 12, a negative terminal post 13, and a heat dissipation cavity 14; the positive terminal post 12 and the negative terminal post 13 are insulated and fixed on the upper cover plate 11, and the heat dissipation cavity 14 is a hollow protrusion integrally formed on the upper cover plate 11 and facing the outside of the battery. The heat dissipation cavity 14 is located between the positive terminal post 12 and the negative terminal post 13.

[0080] One purpose of placing the heat dissipation cavity 14 on the upper cover is to facilitate processing and reduce costs. Another purpose is to ensure that the condensed electrolyte can quickly flow back into the battery. A third purpose is that the hollow protrusion can increase the volume of the battery cavity and improve the battery's pressure resistance.

[0081] In some other embodiments, the heat dissipation cavity 14 may also be provided with a hollow protrusion on the side wall of the cylinder 12.

[0082] It should be noted that in this embodiment, the vaporization temperature of the electrolyte is lower than the decomposition temperature of the SEI film.

[0083] Example 4

[0084] As shown in Figures 1 and 2, this embodiment provides a battery 100, including an upper cover assembly 1, a cylindrical body 2, a lower cover plate 3, and at least one electrode assembly 4; the upper cover assembly 1, the cylindrical body 2, and the lower cover plate 3 together form a shell.

[0085] As shown in Figure 4, in this embodiment, multiple ribs 15 are respectively provided on the inner surfaces of the four side walls of the shell, and each rib 15 forms an electrolyte storage area 6; the remaining part inside the shell is the electrode assembly accommodating area 7. That is to say, in this embodiment, the electrolyte storage area 6 is evenly distributed in the surrounding area of ​​the inner cavity of the shell. The purpose of this arrangement is that the electrolyte can evenly absorb the heat of the battery, and since the inner surfaces of the inner walls of the shell are provided with ribs, the strength and pressure resistance of the battery shell are improved.

[0086] In this embodiment, there may be one or more electrode components 4. If there is one electrode component 4, the positive and negative tabs of the electrode component 4 are directly connected to the positive and negative terminals of the battery, respectively. If there are multiple electrode components 4, the positive tabs of each electrode component 4 are connected to the positive terminal of the battery, and the negative tabs of each electrode component 4 are connected to the negative terminal of the battery.

[0087] For ease of processing, in this embodiment, the cylinder 2 and the lower cover plate 3 are integrally formed by stamping and injection molding. Of course, in some other embodiments, the lower cover plate 3 and the cylinder 2 can also be connected together by welding.

[0088] As shown in Figure 3, in this embodiment, the upper cover assembly 1 includes an upper cover plate 11, a positive terminal post 12, a negative terminal post 13, and a heat dissipation cavity 14; the positive terminal post 12 and the negative terminal post 13 are insulated and fixed on the upper cover plate 11, and the heat dissipation cavity 14 is a hollow protrusion integrally formed on the upper cover plate 11 and facing the outside of the battery. The heat dissipation cavity 14 is located between the positive terminal post 12 and the negative terminal post 13.

[0089] One purpose of placing the heat dissipation cavity 14 on the upper cover is to facilitate processing and reduce costs. Another purpose is to ensure that the condensed electrolyte can quickly flow back into the battery. A third purpose is that the hollow protrusion can increase the volume of the battery cavity and improve the battery's pressure resistance.

[0090] In some other embodiments, the heat dissipation cavity 14 may also be provided with a hollow protrusion on the side wall of the cylinder 12.

[0091] It should be noted that in this embodiment, the vaporization temperature of the electrolyte is lower than the decomposition temperature of the diaphragm.

[0092] Example 5

[0093] As shown in Figures 1 and 2, this embodiment provides a battery 100, including an upper cover assembly 1, a cylindrical body 2, a lower cover plate 3, and at least one electrode assembly 4; the upper cover assembly 1, the cylindrical body 2, and the lower cover plate 3 together form a shell.

[0094] As shown in Figure 5, in this embodiment, the positive tabs in each electrode assembly 4 are connected in parallel and electrically connected to the positive terminal of the battery, and the negative tabs in each electrode assembly 4 are connected in parallel and electrically connected to the negative terminal of the battery; two adjacent electrode assemblies 4 are separated by a partition 5, and the surface of each partition 5 in contact with the electrode assembly 4 is provided with multiple ribs 15, and each rib 15 forms an electrolyte storage area 6, and the partition 5 is provided with a channel connecting the adjacent electrode assembly receiving area 7.

[0095] In this embodiment, a slot is provided inside the cylinder, and the partition is fixed inside the shell by plugging. In some other embodiments, the partition can also be integrally formed on the cylinder by stamping and injection molding.

[0096] In addition, this embodiment can also use the shell as in embodiment 4, with multiple ribs provided on the inner surface of the shell side wall, and the adjacent ribs forming an electrolyte storage area; this arrangement increases the number of electrolyte storage areas, thereby increasing the storage capacity of free electrolyte, and the ribs on the shell can also improve the strength and pressure resistance of the shell.

[0097] The channel can take several forms: one is that the perimeter of the partition has at least one notch; the other is that the partition has at least one through hole, the purpose of which is to ensure that the electrolyte storage area and the electrode assembly housing area are interconnected.

[0098] For ease of processing, in this embodiment the cylinder and the lower cover plate are integrally formed by stamping and injection molding. Of course, in some other embodiments, the lower cover plate and the cylinder can also be connected together by welding.

[0099] In this embodiment, the upper cover assembly 1 includes an upper cover plate 11, a positive terminal post 12, a negative terminal post 13, and a heat dissipation cavity 14; the positive terminal post 12 and the negative terminal post 13 are insulated and fixed on the upper cover plate 11, and the heat dissipation cavity 14 is a hollow protrusion integrally formed on the upper cover plate 11 and facing the outside of the battery, and the heat dissipation cavity 14 is located between the positive terminal post 12 and the negative terminal post 13.

[0100] One purpose of placing the heat dissipation cavity 14 on the upper cover is to facilitate processing and reduce costs. Another purpose is to ensure that the condensed electrolyte can quickly flow back into the battery. A third purpose is that the hollow protrusion can increase the volume of the battery cavity and improve the battery's pressure resistance.

[0101] In some other embodiments, the heat dissipation cavity 14 may also be provided with a hollow protrusion on the side wall of the cylinder 12.

[0102] Example 6

[0103] This embodiment is an improvement on the heat dissipation cavity 14 based on the above embodiments 3 to 5, and its purpose is to improve the condensation effect of the heat dissipation cavity on electrolyte vapor;

[0104] Improvement 1: In order to improve the effect of natural air cooling, heat dissipation fins 141 are provided on the outer surface of the heat dissipation cavity 14, as shown in Figure 6;

[0105] Improvement 2: A semiconductor cooling chip is provided on the outer surface of the heat dissipation cavity 14; Improvement 2 can be provided separately on the heat dissipation cavity 14, or it can be provided together with Improvement 1 on the heat dissipation cavity 14.

[0106] Improvement 3: Enhance the condensation effect of electrolyte vapor in the heat dissipation cavity 14 by liquid cooling, that is, set up a liquid cooling channel 142 on the heat dissipation cavity 14, as shown in Figure 7; the liquid cooling channel 142 can be set up in the following two ways: Form 1: directly set up a liquid cooling plate on the outer surface of the heat dissipation cavity; Form 2: set up a liquid cooling channel on at least one side wall of the heat dissipation cavity.

Claims

1. An electrolyte, characterized in that, It includes at least one solvent with a vaporization temperature below the SEI film decomposition temperature, and the solvent with a vaporization temperature below the SEI film decomposition temperature has a mass percentage content of more than 10% in the electrolyte.

2. The electrolyte according to claim 1, characterized in that, The percentage of solvents with vaporization temperatures below the SEI film decomposition temperature in the electrolyte is above 20%.

3. The electrolyte according to claim 2, characterized in that, The percentage of solvents with vaporization temperatures below the SEI film decomposition temperature in the electrolyte is above 30%.

4. The electrolyte according to any one of claims 1 to 3, characterized in that, It includes at least one solvent with a vaporization temperature below 90°C.

5. The electrolyte according to claim 4, characterized in that, It includes at least one solvent with a vaporization temperature below 75°C.

6. The electrolyte according to claim 5, characterized in that, Solvents with a vaporization temperature below 75°C include methyl formate, ethyl formate, methyl acetate, tetrahydrofuran, dioxolane, and ethyl trifluoroacetate.

7. The electrolyte according to claim 6, characterized in that, Solvents with a vaporization temperature below 75°C include dioxolane.

8. A battery, characterized in that, The battery contains the electrolyte as described in any one of claims 1 to 7.

9. A battery, comprising a casing and an electrode assembly; characterized in that, The casing is provided with a heat dissipation cavity that communicates with the inner cavity of the battery. After the battery heats up, the electrolyte vaporizes into electrolyte vapor and enters the heat dissipation cavity. The heat dissipation cavity condenses the electrolyte vapor into liquid and then returns it to the casing.

10. The battery according to claim 9, characterized in that, The housing includes an electrode assembly accommodating area and an electrolyte storage area; the electrode assembly accommodating area is connected to the electrolyte storage area, and at least one electrode assembly is provided in the electrode assembly accommodating area.

11. The battery according to claim 10, characterized in that, It also includes a partition; the partition is disposed inside the housing to separate the electrolyte storage area and the electrode assembly receiving area; the partition is provided with at least one channel for connecting the electrolyte storage area and the electrode assembly receiving area.

12. The battery according to claim 10, characterized in that, At least one inner surface of the side wall of the shell is provided with a plurality of ribs, and the electrolyte storage area is formed between each rib.

13. The battery according to claim 10, characterized in that, It also includes multiple partitions, with two partitions forming an electrode assembly receiving area for placing electrode assemblies. Each partition has multiple ribs on its surface that contacts the electrode assembly, with each rib forming an electrolyte storage area. The partitions also have channels connecting adjacent electrode assembly receiving areas.

14. The battery according to claim 9, characterized in that, The heat dissipation cavity is integrally formed on the top of the shell.

15. The battery according to any one of claims 9 to 14, characterized in that, The outer surface of the heat dissipation cavity is provided with at least one of heat dissipation fins and a semiconductor cooling chip.

16. The battery according to any one of claims 9 to 14, characterized in that, At least one side wall of the heat dissipation cavity is provided with a liquid cooling channel.

17. The battery according to claim 9, characterized in that, The vaporization temperature of the electrolyte is lower than the decomposition temperature of the SEI film.

18. The battery according to claim 9, characterized in that, The vaporization temperature of the electrolyte is lower than the decomposition temperature of the diaphragm.

19. A top cover assembly for a battery, characterized in that, It includes a top cover plate, a positive electrode post, a negative electrode post, and a heat dissipation cavity; the positive electrode post and the negative electrode post are insulated and sealed to the top cover plate; the heat dissipation cavity is integrally formed on the top cover plate and is located between the positive electrode post and the negative electrode post, and is used to condense the electrolyte vapor into liquid and return it to the battery casing after the battery is heated.

20. The cover assembly according to claim 19, characterized in that, The outer surface of the heat dissipation cavity is provided with at least one of heat dissipation fins and a semiconductor cooling chip, or at least one side wall of the heat dissipation cavity is provided with a liquid cooling channel.

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