Temperature-sensitive gas production composition and application thereof in improving safety performance of lithium ion battery

Abstract

The invention provides a temperature-sensitive gas production composition and application thereof in improving the safety performance of a lithium ion battery. When the temperature of the temperature-sensitive gas production composition is lower than 90 DEG C, the temperature-sensitive gas production composition is stable and does not produce any gas; when the temperature-sensitive gas production composition is heated to 100 DEG C or above (such as 100-140 DEG C), the temperature-sensitive gas production composition can produce gas with the volume being 100 times or above of the volume of the temperature-sensitive gas production composition; when the temperature-sensitive gas production structural member is used for the lithium ion battery, the temperature-sensitive gas production structural member is independently packaged and is not in direct contact with an electrolyte in a battery cell, so that the cycle performance of the battery is not influenced; when the thermal runaway temperature of the battery is increased, a large amount of inert gas can be quickly released in the battery cell, the generated pressure enables the pressure release valve to be opened, the safety valve or the aluminum-plastic package to be broken through, flammable organic solvent steam is discharged, heat is taken away, the risks of fire catching and explosion are reduced, and therefore the safety performance of the lithium ion battery is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries, and particularly relates to a thermosensitive gas-generating composition and its use in improving the safety performance of lithium-ion batteries. Background Art

[0002] Due to their high energy density and long cycle life, lithium-ion batteries are increasingly widely used in life. However, due to the use of flammable organic liquid electrolytes, when lithium-ion batteries are affected by abnormal factors such as short circuit, high heat, overcharge, etc., the temperature inside the battery will rise sharply, posing potential safety hazards of fire and explosion. Summary of the Invention

[0003] The inventors of the present application found through research that in order to solve the problem of battery safety performance, many existing researchers have adopted the method of adding functional additives to improve the safety performance of lithium-ion batteries. For example, Chinese Patent Document CN219267730U mentions a kind of ester phase change material that changes from liquid to gas, and controls the battery temperature below 60°C by phase change heat absorption to improve the battery safety performance; for example, Chinese Patent Document CN115020791A mentions a method of adding a flame retardant to the PP film wrapping the battery core to improve the battery safety performance; and for example, Chinese Patent Document CN119542702A mentions a method of coating a functional coating containing a foaming agent on the edge of the current collector of the separator and the electrode sheet to improve the safety performance of a single battery.

[0004] However, in these reported methods, whether it is a phase change material, a flame retardant or a foaming agent, these substances are directly in contact with the electrolyte when introduced into the battery core. Therefore, when selecting materials, it is necessary to consider the compatibility with the electrolyte system, which results in very limited materials that can be actually applied to the battery core. Moreover, for the selection of phase change materials and foaming agents, it is also necessary to consider their initial decomposition temperature. If the initial decomposition temperature is relatively low, during the battery manufacturing process when the battery is dried, the phase change material or foaming agent will decompose at the drying temperature, which requires using products with an initial decomposition temperature higher than the normal drying temperature of the battery core; but if the initial decomposition temperature is too high, it will cause the battery to be in a thermal runaway state and the phase change material or foaming agent cannot play its role, which makes the materials that can be actually applied even more limited. At the same time, the selected materials are not completely insoluble in the electrolyte. Even if they are slightly soluble, they will inevitably enter the electrolyte and participate in the internal reactions of the battery, leading to the deterioration of electrochemical performances such as the cycle performance of the battery. Therefore, it is necessary to develop a functional additive that does not sacrifice the cycle performance of the battery to improve the safety performance of the battery.

[0005] The inventors of this application have also discovered that, in addition to adding additives with specific functions within the battery, a variety of design options can be employed within the battery casing to enhance battery safety. The most common of these is the provision of a pressure relief valve or safety valve on the battery cover. The operating principle of a pressure relief valve or safety valve is that when the internal temperature of the battery rises, the solvent in the electrolyte vaporizes, causing the internal pressure to increase to a certain threshold. The pressure relief valve or safety valve then opens or the explosion-proof disc within the safety valve ruptures, reducing the internal pressure of the battery, thereby preventing the battery from catching fire or exploding and providing safety protection. However, the threshold of the pressure relief valve or safety valve can affect the sealing of the battery casing and the refilling of the electrolyte. To ensure the sealing of the battery casing without affecting the refilling of the electrolyte, the threshold of the pressure relief valve or safety valve is typically set to greater than 0.5 MPa. However, in actual use, when the gassing of the lithium-ion battery cell causes the internal pressure to reach or exceed 0.5 MPa, the internal temperature of the battery has already exceeded the flash point of the solvent in the electrolyte. This can result in the battery catching fire or even exploding before the pressure relief valve or safety valve has even taken effect.

[0006] The inventors also discovered that the separators in existing lithium-ion batteries are mostly polyolefins. Due to the relatively low melting point of polyolefins (typically 130-165°C), when the temperature rises above 140°C, the separators will melt and collapse, causing thermal runaway of the battery. This means that when the internal temperature of the battery reaches 140°C, the battery has already caught fire or is close to a thermal runaway state, such as ignition or explosion. In the solution reported in Chinese patent document CN119542702A, a foaming agent coated on the edges of the separator and the positive and negative current collectors begins to decompose and produce gas only after the temperature exceeds 140°C. The expansion of the gas expands the positive and negative electrode sheets, reducing the contact area that could cause a short circuit and improving battery safety.

[0007] After repeated research on the safety performance of lithium-ion batteries, the inventors of the present application believe that if the pressure relief valve, safety valve or packaging materials such as aluminum-plastic film can be opened before the diaphragm melts on a large scale, the high-temperature steam in the battery cell can be released and the heat can be taken away, and the internal temperature will not reach above the flash point of the solvent in the electrolyte. In this way, the battery will not enter a thermal runaway state, and the safety of the battery can be truly guaranteed.

[0008] In order to improve the safety problems existing in existing lithium-ion batteries and better play the safety protection role of a pressure relief valve or a safety valve, the present invention provides a temperature-sensitive gas-generating composition, a temperature-sensitive gas-generating structural member including the temperature-sensitive gas-generating composition, and the uses of both in enhancing the safety performance of lithium-ion batteries; the use of the temperature-sensitive gas-generating composition enables the battery to rapidly release gas before the diaphragm melts and collapses due to large-area thermal runaway of the battery and the temperature reaches the flash point of the solvent in the electrolyte, generates pressure inside the battery, opens the pressure relief valve, breaks through the explosion-proof sheet of the safety valve, or breaks through packaging materials such as aluminum-plastic films, timely discharges the solvent vapor inside the battery and takes away heat, thereby enhancing the safety of the battery.

[0009] Specifically, when the temperature of the temperature-sensitive gas-generating composition is lower than 90 °C, the material is stable and does not generate any gas; when it is heated to above 100 °C (such as 100 - 140 °C), the temperature-sensitive gas-generating composition can generate more than 100 times its own volume of gas; when the temperature-sensitive gas-generating structural member including the temperature-sensitive gas-generating composition is used in a lithium-ion battery, the temperature-sensitive gas-generating structural member is separately packaged and does not directly contact the electrolyte in the battery cell, and does not affect the electrochemical performance such as the cycle performance of the battery; when the thermal runaway temperature of the battery rises, it can rapidly release a large amount of inert gas inside the battery cell, and the generated pressure opens the pressure relief valve, breaks through the safety valve or packaging materials such as aluminum-plastic films, discharges the flammable solvent vapor and takes away heat, reducing the risk of fire and explosion, thereby achieving the improvement of the safety performance of lithium-ion batteries.

[0010] The object of the present invention is achieved by the following technical solutions:

[0011] A temperature-sensitive gas-generating composition, wherein the temperature-sensitive gas-generating composition includes a main material; or the temperature-sensitive gas-generating composition includes a main material and an additive;

[0012] The main material is selected from at least one of di(azoamino)benzene, azodicarbonamide, barium azodicarboxylate, azodicarboxylate, diisopropyl azodicarboxylate, N,N′-di-nitrosopentamethylenetetramine, N,N′-dimethyl-N,N′-dinitrosoterephthalamide, trinitrosotrimethylenetriamine, 4,4′-oxybis(benzenesulfonylhydrazide), 3,3′-disulfonylhydrazide diphenyl sulfone, benzenesulfonylhydrazide, p-toluenesulfonylhydrazide, 2,4-toluenedisulfonylhydrazide, and p-(N-methoxyformamido)benzenesulfonylhydrazide;

[0013] The gas generation temperature of the temperature-sensitive gas-generating composition is 100 - 140 °C.

[0014] According to an embodiment of the present invention, the gas generation temperature of the temperature-sensitive gas-generating composition is 100 - 140 °C, such as 100 °C, 110 °C, 120 °C, 130 °C, or 140 °C.

[0015] According to the embodiments of the present invention, as described above, the inventors of the present application discovered through research that the primary safety concern of lithium-ion batteries is that when the temperature rises to 140°C, the diaphragm melts, causing a large-scale short circuit, which can lead to thermal runaway of the battery and cause fire and explosion. The temperature-sensitive gas generating composition of the present application has a gas generation temperature of 100-140°C. Within this temperature range, the diaphragm has not yet undergone large-scale melting. In other words, before the diaphragm has undergone large-scale melting, the temperature-sensitive gas generating composition of the present invention will generate a large amount of gas. This gas can open the pressure relief valve, break through the safety valve or the aluminum-plastic film, release high-temperature steam, and remove heat, preventing the battery interior from exceeding the flash point of the solvent in the electrolyte, thereby fundamentally improving the safety of the battery.

[0016] According to an embodiment of the present invention, the additive is selected from at least one of a first additive, a second additive and a flame retardant; the first additive is an additive capable of reducing the gas generation temperature of the main material; and the second additive is an additive capable of absorbing hydrogen fluoride.

[0017] According to an embodiment of the present invention, the temperature-sensitive gas generating composition is composed of a host material, or the temperature-sensitive gas generating composition is composed of a host material and an additive.

[0018] According to an embodiment of the present invention, the first additive is selected from at least one of zinc oxide, zinc chloride, zinc stannate, zinc acetate, zirconium chloride, magnesium oxide, magnesium chloride, titanium dioxide, iron powder, organic acid salt, urea, biuret, triuret, cyanuric acid, ethanolamine, malonyl urea, semicarbazide, organic acid and borax.

[0019] According to an embodiment of the present invention, the addition of the first additive can catalyze the decomposition of the main material, causing the main material to produce gas at a specific temperature (such as 100-140°C); that is, when the main material and the first additive are mixed, the gas production temperature of the main material can be reduced.

[0020] According to an embodiment of the present invention, the second additive is selected from at least one of triethanolamine, sodium carbonate, potassium carbonate, zinc carbonate, aluminum hydroxide and magnesium hydroxide.

[0021] According to an embodiment of the present invention, the second additive is an additive capable of absorbing hydrogen fluoride. The addition of the second additive can react with the hydrogen fluoride in the solvent vapor in the electrolyte, thereby reducing the harm of hydrogen fluoride to the environment and human body.

[0022] According to an embodiment of the present invention, the mass of the main body material accounts for 50-100 wt% of the total mass of the temperature-sensitive gas-generating composition, preferably 50-99 wt%, for example 60-90 wt%, such as 70-85 wt%, such as 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt% or 99 wt%.

[0023] According to an embodiment of the present invention, the mass of the first additive accounts for 0-50 wt% of the total mass of the temperature-sensitive gas-generating composition; the mass of the second additive accounts for 0-10 wt% of the total mass of the temperature-sensitive gas-generating composition; the mass of the flame retardant accounts for 0-50 wt% of the total mass of the temperature-sensitive gas-generating composition.

[0024] According to an embodiment of the present invention, the total mass of the first additive, the second additive and the flame retardant accounts for 1-50 wt% of the total mass of the temperature-sensitive gas-generating composition, for example 10-40 wt%, such as 1 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt% or 50 wt%.

[0025] Exemplarily, the mass of the first additive accounts for 1 wt%, 2 wt%, 3 wt%, 5 wt%, 8 wt%, 10 wt%, 12 wt%, 15 wt%, 16 wt%, 18 wt%, 20 wt%, 24 wt%, 25 wt%, 26 wt%, 28 wt%, 30 wt%, 32 wt%, 35 wt%, 36 wt%, 38 wt%, 40 wt%, 42 wt%, 45 wt%, 48 wt% or 50 wt% of the total mass of the temperature-sensitive gas-generating composition.

[0026] Exemplarily, the mass of the second additive accounts for 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt% or 10 wt% of the total mass of the temperature-sensitive gas-generating composition.

[0027] Exemplarily, the mass of the flame retardant accounts for 1 wt%, 2 wt%, 3 wt%, 5 wt%, 8 wt%, 10 wt%, 12 wt%, 15 wt%, 16 wt%, 18 wt%, 20 wt%, 24 wt%, 25 wt%, 26 wt%, 28 wt%, 30 wt%, 32 wt%, 35 wt%, 36 wt%, 38 wt%, 40 wt%, 42 wt%, 45 wt%, 48 wt% or 50 wt% of the total mass of the temperature-sensitive gas-generating composition.

[0028] According to an embodiment of the present invention, the gas generation temperature of the main body material is 100 - 250°C, preferably 105 - 230°C. By introducing a first additive into the main body material, the gas generation temperature of the obtained temperature-sensitive gas generation composition can be adjusted within the range of 100 - 140°C, giving full play to its role and significantly improving the safety performance of the battery.

[0029] According to an embodiment of the present invention, the addition of the flame retardant can reduce the combustion rate, slow down the spread of fire, and play a role in flame retardant and self-extinguishing.

[0030] According to an embodiment of the present invention, the flame retardant is selected from at least one of inorganic flame retardants, halogen-based flame retardants, phosphorus-based flame retardants, silicon-based flame retardants or intumescent flame retardants.

[0031] According to an embodiment of the present invention, the inorganic flame retardant is selected from aluminum hydroxide, magnesium hydroxide, antimony trioxide, etc. The halogen-based flame retardant is selected from decabromodiphenyl ether, tetrabromobisphenol A, brominated polystyrene, chlorinated paraffin, tetrachlorobisphenol A, etc. The phosphorus-based flame retardant is selected from red phosphorus, tris(2,3-dibromopropyl) phosphate, tris(1-chloropropyl) phosphate, phosphaphenanthrene and its derivatives, phosphonitrile and its derivatives, etc. The silicon-based flame retardant is selected from polysiloxane, polysiloxaboroxane, silicon dioxide, montmorillonite, talcum powder, etc.

[0032] The present invention also provides a preparation method of the above temperature-sensitive gas generation composition, and the method comprises the following steps:

[0033] Mix and grind the main body material and an optionally added or unadded additive to prepare the temperature-sensitive gas generation composition.

[0034] The present invention also provides a temperature-sensitive gas generation structural member, which comprises the above temperature-sensitive gas generation composition and a packaging film, and the packaging film is encapsulated on the outer surface of the temperature-sensitive gas generation composition.

[0035] According to an embodiment of the present invention, the packaging film is encapsulated on the outer surface of the temperature-sensitive gas generation composition to form the temperature-sensitive gas generation structural member.

[0036] According to an embodiment of the present invention, the packaging film is selected from at least one of polyethylene heat-sealing film, polypropylene heat-sealing film, polyester heat-sealing film or aluminum-plastic packaging film.

[0037] According to an embodiment of the present invention, the thickness of the packaging film is 10 - 100 μm, for example, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm.

[0038] According to an embodiment of the present invention, the shape and size of the temperature-sensitive gas-generating structural member are not particularly limited and can be appropriately selected according to the size of the battery and the installation position of the temperature-sensitive gas-generating structural member. Exemplarily, the shape of the temperature-sensitive gas-generating structural member can be rectangular, square, circular, oval or other shapes.

[0039] According to an embodiment of the present invention, the thickness of the temperature-sensitive gas-generating structural member is 0.05 - 50 mm, such as 0.05 mm, 0.1 mm, 0.2 mm, 0.5 mm, 0.8 mm, 1 mm, 2 mm, 5 mm, 8 mm, 10 mm, 15 mm, 20 mm, 25 mm, 30 mm, 40 mm or 50 mm.

[0040] According to an embodiment of the present invention, the mass of the temperature-sensitive gas-generating composition in the temperature-sensitive gas-generating structural member is 0.1 - 10 g, preferably 0.3 - 5 g, such as 0.5 - 3 g, such as 1 g or 2 g.

[0041] According to an embodiment of the present invention, the temperature-sensitive gas-generating structural member is placed in a lithium-ion battery.

[0042] The present invention also provides a method for preparing the above-mentioned temperature-sensitive gas-generating structural member, the method comprising the following steps:

[0043] Press the temperature-sensitive gas-generating composition into a shape, and then encapsulate the temperature-sensitive gas-generating composition after pressing with a packaging film to obtain the temperature-sensitive gas-generating structural member.

[0044] Exemplarily, 0.1 - 10 g of the temperature-sensitive gas-generating composition is pressed into a tablet shape by a tablet press, and then the temperature-sensitive gas-generating composition after pressing is encapsulated with a packaging film to obtain the temperature-sensitive gas-generating structural member.

[0045] The present invention also provides a lithium-ion battery, the lithium-ion battery comprising the above-mentioned temperature-sensitive gas-generating structural member, and the temperature-sensitive gas-generating structural member is arranged between the outer shell and the battery core of the lithium-ion battery.

[0046] According to an embodiment of the present invention, the outer shell can be a hard shell or an aluminum-plastic film; the hard shell is, for example, a plastic shell or an aluminum shell.

[0047] According to an embodiment of the present invention, when the lithium-ion battery is a hard-shell lithium-ion battery (such as a plastic-shell lithium-ion battery or an aluminum-shell lithium-ion battery), the temperature-sensitive gas-generating structural member is placed between the battery core and the hard shell, and can be placed, for example, at a position close to the pressure relief valve, at a position close to the safety valve, at a position between the pole ear and the safety valve away from the liquid injection port, at a position between the pole ear and the pressure relief valve away from the liquid injection port, at a position between the two pole ears, or at a position at the inner bottom of the hard shell.

[0048] Exemplarily, the lithium-ion battery includes: a hard case, an electrode core, and a temperature-sensitive gas-generating structural member; a positive electrode terminal, a negative electrode terminal, a pressure relief valve or a safety valve is provided on the hard case; the electrode core includes a positive electrode sheet, a negative electrode sheet, a positive electrode tab, a negative electrode tab, and a separator;

[0049] The electrode core is disposed inside the hard case; the hard case is filled with an electrolyte to soak the electrode core; the positive electrode sheet is connected to the positive electrode terminal through the positive electrode tab, and the negative electrode sheet is connected to the negative electrode terminal through the negative electrode tab;

[0050] The temperature-sensitive gas-generating structural member is disposed at a position close to the pressure relief valve, a position close to the safety valve, a position between the tab and the safety valve far from the liquid injection port, a position between the tab and the pressure relief valve far from the liquid injection port, a position between the two tabs, or a position at the inner bottom of the hard case.

[0051] According to an embodiment of the present invention, when the lithium-ion battery is a soft-pack lithium-ion battery (such as a soft-pack lithium-ion battery packaged with an aluminum plastic film), the temperature-sensitive gas-generating structural member is placed between the electrode core and the aluminum plastic film. For example, it can be placed at a position close to the second sealing edge of the aluminum plastic film (i.e., a position close to the airbag), a position between the two tabs, or one or two surfaces with a larger area on the side of the electrode core.

[0052] Exemplarily, the lithium-ion battery includes: an aluminum plastic film, an electrode core, and a temperature-sensitive gas-generating structural member; a positive electrode foil and a negative electrode foil are provided on the aluminum plastic film; the electrode core includes a positive electrode sheet, a negative electrode sheet, a positive electrode tab, a negative electrode tab, and a separator;

[0053] The electrode core is disposed inside the aluminum plastic film; the aluminum plastic film is filled with an electrolyte to soak the electrode core; the positive electrode sheet is connected to the positive electrode foil through the positive electrode tab, and the negative electrode sheet is connected to the negative electrode foil through the negative electrode tab; the aluminum plastic film includes a top sealing edge, a side sealing edge, a folding edge, and a second sealing edge; the side sealing edge and the top sealing edge are adjacent to the folding edge, and the side sealing edge and the second sealing edge are opposite;

[0054] The temperature-sensitive gas-generating structural member is disposed at a position close to the second sealing edge of the aluminum plastic film (i.e., a position close to the airbag), a position between the two tabs, or one or two surfaces with a larger area on the side of the electrode core.

[0055] The present invention also provides a method for manufacturing the above lithium-ion battery. The method includes: during the manufacturing process of the lithium-ion battery, placing the above temperature-sensitive gas-generating structural member between the outer shell and the electrode core of the lithium-ion battery.

[0056] According to an embodiment of the present invention, when the lithium-ion battery is a hard-shell lithium-ion battery (such as a plastic-shell lithium-ion battery or an aluminum-shell lithium-ion battery), the temperature-sensitive gas-generating structural member is placed between the battery cell and the hard shell. For example, it can be placed at a position close to the pressure relief valve, a position close to the safety valve, a position between the electrode tab and the safety valve away from the liquid injection port, a position between the electrode tab and the pressure relief valve away from the liquid injection port, a position between the two electrode tabs, or a position at the inner bottom of the hard shell.

[0057] According to an embodiment of the present invention, when the lithium-ion battery is a soft-pack lithium-ion battery (such as a soft-pack lithium-ion battery packaged with an aluminum plastic film), the temperature-sensitive gas-generating structural member is placed between the battery cell and the aluminum plastic film. For example, it can be placed at a position close to the second sealing edge of the aluminum plastic film (i.e., a position close to the airbag), a position between the two electrode tabs, or on one or two surfaces with a larger area on the side of the battery cell.

[0058] The present invention also provides a method for improving the safety performance of a lithium-ion battery. The method includes: during the assembly process of the lithium-ion battery, encapsulating the above-mentioned temperature-sensitive gas-generating structural member between the outer shell and the battery cell of the lithium-ion battery.

[0059] The present invention also provides the use of the above-mentioned temperature-sensitive gas-generating composition and temperature-sensitive gas-generating structural member in a lithium-ion battery.

[0060] Preferably, the use of the temperature-sensitive gas-generating composition and temperature-sensitive gas-generating structural member in improving the safety performance of a lithium-ion battery.

[0061] Advantages of the present invention:

[0062] The present invention provides a temperature-sensitive gas-generating composition, a temperature-sensitive gas-generating structural member including the temperature-sensitive gas-generating composition, and the use of both in improving the safety performance of a lithium-ion battery. When the temperature-sensitive gas-generating composition is at a temperature lower than 90°C, the material is stable and does not generate any gas. When it is heated to above 100°C (such as 100 - 140°C), the temperature-sensitive gas-generating composition can generate gases more than 100 times its own volume. When the temperature-sensitive gas-generating structural member is used in a lithium-ion battery, the temperature-sensitive gas-generating structural member is packaged separately and does not directly contact the electrolyte in the battery cell, thus not affecting the cycle performance of the battery. When the thermal runaway temperature of the battery rises, it can quickly release a large amount of inert gas inside the battery cell. The generated pressure causes the pressure relief valve to be opened, and packaging materials such as the safety valve or the aluminum plastic film to be broken through, discharging the flammable organic solvent vapor and taking away heat, reducing the risk of fire and explosion, thereby achieving the improvement of the safety performance of the lithium-ion battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 It is a schematic structural diagram of a lithium-ion battery according to a preferred embodiment of the present invention.

[0064] Figure 2Schematic diagram of the structure of a lithium-ion battery according to a preferred embodiment of the present invention.

[0065] Figure 3 Schematic diagram of the structure of a lithium-ion battery according to a preferred embodiment of the present invention.

[0066] Figure 4 Schematic diagram of the working principle of a lithium-ion battery according to a preferred embodiment of the present invention.

[0067] Reference numerals: 1 is a hard shell, 2 is an electrode core, 3 is a temperature-sensitive gas-generating structural member, 4 is a positive electrode terminal, 5 is a negative electrode terminal, 6 is a pressure relief valve or safety valve, 7 is a positive electrode tab, 8 is a negative electrode tab, 11 is an aluminum-plastic film, 41 is a positive electrode foil, 51 is a negative electrode foil, 111 is a top sealing edge, 112 is a side sealing edge, 113 is a folding edge, 114 is a second sealing edge. Detailed Description of the Invention

[0068] The technical solutions of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are only illustrative explanations of the present invention and should not be construed as limiting the protection scope of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0069] Unless otherwise specified, the experimental methods used in the following embodiments are all conventional methods; unless otherwise specified, the reagents, materials, etc. used in the following embodiments can all be obtained from commercial sources.

[0070] Figure 1 Schematic diagram of the structure of a lithium-ion battery according to a preferred embodiment of the present invention. As Figure 1 shown, the lithium-ion battery includes: a hard shell 1, an electrode core 2, and a temperature-sensitive gas-generating structural member 3; a positive electrode terminal 4, a negative electrode terminal 5, and a pressure relief valve or safety valve 6 are provided on the hard shell 1; the electrode core includes a positive electrode sheet, a negative electrode sheet, a positive electrode tab 7, a negative electrode tab 8, and a separator;

[0071] The electrode core 2 is disposed inside the hard shell 1; the inside of the hard shell 1 is filled with electrolyte to soak the electrode core 2; the positive electrode sheet is connected to the positive electrode terminal 4 through the positive electrode tab 7, and the negative electrode sheet is connected to the negative electrode terminal 5 through the negative electrode tab 8;

[0072] The temperature-sensitive gas-generating structural member 3 is disposed at a position between the positive electrode tab 7 and the negative electrode tab 8.

[0073] When the temperature inside the hard shell 1 is higher than the set threshold, the temperature-sensitive gas-generating structural member 3 can generate a large amount of gas, and the formed gas increases the pressure inside the hard shell 1. When the pressure inside the hard shell 1 is greater than the set pressure of the pressure relief valve or safety valve 6, the pressure relief valve is opened or the safety valve is broken through, and the high-temperature material (such as electrolyte) inside the hard shell 1 is taken out of the hard shell 1, so as to quickly reduce the temperature inside the hard shell 1.

[0074] Specifically, Figure 4 is a schematic diagram of the working principle of the lithium-ion battery according to a preferred embodiment of the present invention. Refer to Figure 4 , the temperature-sensitive gas-generating structural member 3 is solid and has a small volume at normal temperature, which will not generate any pressure on the hard shell 1, and the pressure relief valve or safety valve 6 is in a closed state. When the single battery is in a fault state and the temperature inside the hard shell 1 rises to a given threshold (such as 100-140 °C), the temperature-sensitive gas-generating material in the temperature-sensitive gas-generating structural member 3 changes from solid to gas, and the volume rapidly increases. The generated gas rapidly increases the pressure inside the hard shell 1 under the constraint of the hard shell 1 (the volume of the hard shell 1 cannot increase arbitrarily), the pressure relief valve is opened or the safety valve is broken through, forming a pressure relief channel, and discharging the high-temperature material (such as electrolyte) inside the hard shell 1 out of the hard shell 1, and the temperature inside the hard shell 1 is rapidly reduced, thus avoiding the combustion of the single battery due to excessive temperature. Within the temperature range of 100-140 °C, the diaphragm has not melted in a large area, that is, before the diaphragm melts in a large area, the temperature-sensitive gas-generating material will generate a large amount of gas, and the gas flushes open the pressure relief valve, forming a pressure relief channel, releasing the high-temperature steam and taking away the heat, avoiding the temperature inside the battery reaching above the flash point of the electrolyte solvent, and leading out the heat inside the single battery before the single battery has a thermal runaway combustion, and avoiding the combustion of the battery pack by discharging the heat inside the single battery in advance, so as to achieve the purpose of battery thermal management.

[0075] Figure 2 is a schematic diagram of the structure of the lithium-ion battery according to a preferred embodiment of the present invention. As Figure 2 shown, the lithium-ion battery includes: a hard shell 1, a battery cell 2 and a temperature-sensitive gas-generating structural member 3; a positive electrode terminal 4, a negative electrode terminal 5, a pressure relief valve or safety valve 6 are arranged on the hard shell 1; the battery cell includes a positive electrode plate, a negative electrode plate, a positive electrode tab 7, a negative electrode tab 8 and a diaphragm; the battery cell 2 is arranged inside the hard shell 1; the hard shell 1 is filled with electrolyte to soak the battery cell 2; the positive electrode plate is connected to the positive electrode terminal 4 through the positive electrode tab 7, and the negative electrode plate is connected to the negative electrode terminal 5 through the negative electrode tab 8; the temperature-sensitive gas-generating structural member 3 is arranged at the inner bottom of the hard shell 1.

[0076] Figure 3Schematic diagram of the structure of a lithium-ion battery according to a preferred embodiment of the present invention. The lithium-ion battery includes: an aluminum-plastic film 11, a battery cell 2, and a temperature-sensitive gas-generating structural member 3; a positive electrode foil 41 and a negative electrode foil 51 are provided on the aluminum-plastic film 11; the battery cell includes a positive electrode sheet, a negative electrode sheet, a positive electrode tab 7, a negative electrode tab 8, and a separator; the battery cell 2 is disposed inside the aluminum-plastic film 11; the inside of the aluminum-plastic film 11 is filled with an electrolyte to soak the battery cell 2; the positive electrode sheet is connected to the positive electrode foil 41 through the positive electrode tab 7, and the negative electrode sheet is connected to the negative electrode foil 51 through the negative electrode tab 8; the aluminum-plastic film 11 includes a top sealing edge 111, a side sealing edge 112, a folding edge 113, and a second sealing edge 114; the side sealing edge 112 and the top sealing edge 111 are adjacent to the folding edge 113, and the side sealing edge 112 and the second sealing edge 114 are opposite; the temperature-sensitive gas-generating structural member 3 is disposed at a position close to the second sealing edge 114 of the aluminum-plastic film 11 between the aluminum-plastic film 11 and the battery cell 2.

[0077] Example 1

[0078] 1.5 g of N,N'-dimethyl-N,N'-dinitrosoterephthalamide (main material) and 0.5 g of chlorinated paraffin (flame retardant) were mixed evenly and pressed into tablets, and then sealed and packaged with an aluminum-plastic film to obtain a temperature-sensitive gas-generating structural member. During the assembly of a plastic-shell lithium-ion battery, the temperature-sensitive gas-generating structural member was placed at a position far from the liquid injection port between the electrode tab and the safety valve, and a plastic-shell lithium-ion battery containing the temperature-sensitive gas-generating structural member was obtained. Since the temperature-sensitive gas-generating composition placed inside the battery did not directly contact the electrolyte, it did not affect the electrochemical performance of the battery. After placing this plastic-shell lithium-ion battery in an oven at 120 °C for 8 minutes, the explosion-proof film of the safety valve was broken, that is, the internal high-pressure organic solvent vapor was released before the internal temperature of the battery reached the flash point of the electrolyte solvent, preventing the battery from catching fire or exploding.

[0079] Example 2

[0080] 3.0 g of diethyl azodicarboxylate (main material), 0.3 g of zinc carbonate (second additive), and 1 g of tris(2,3-dibromopropyl) phosphate (flame retardant) were mixed evenly and pressed into tablets, and then sealed and packaged with a polypropylene heat-sealing film to obtain a temperature-sensitive gas-generating structural member. During the assembly of a soft-pack lithium-ion battery packaged with an aluminum-plastic film, the temperature-sensitive gas-generating structural member was placed at a position close to the second sealing edge of the aluminum-plastic film (i.e., close to the airbag), and a soft-pack lithium-ion battery containing the temperature-sensitive gas-generating structural member was obtained. Since the temperature-sensitive gas-generating composition placed inside the battery did not directly contact the electrolyte, it did not affect the electrochemical performance of the battery. After placing this soft-pack lithium-ion battery in an oven at 125 °C for 3 minutes, the aluminum-plastic packaging film was broken, that is, the internal high-pressure organic solvent vapor was released before the internal temperature of the battery reached the flash point of the electrolyte solvent, preventing the battery from catching fire or exploding.

[0081] Example 3

[0082] 5.2 g of 1,3-benzenedisulfonyl hydrazide (main material), 0.4 g of zinc acetate (first additive), 0.5 g of antimony trioxide (flame retardant), and 0.2 g of tris(1-chloropropyl) phosphate (flame retardant) were mixed evenly and then pressed into tablets, which were sealed and packaged with a polyethylene heat-sealing film to obtain a thermosensitive gas-generating structural member. When assembling an aluminum-shell lithium-ion battery, the thermosensitive gas-generating structural member was placed at a position between the tab and the safety valve and away from the liquid injection port to obtain an aluminum-shell lithium-ion battery containing the thermosensitive gas-generating structural member. Since the thermosensitive gas-generating composition placed inside the battery did not directly contact the electrolyte, it would not affect the electrochemical performance of the battery. This aluminum-shell lithium-ion battery was placed in an oven at 90 °C for 24 hours, and there was no change in the appearance of the battery. After this aluminum-shell lithium-ion battery was placed in an oven at 130 °C for 5 minutes, the explosion-proof film of the safety valve was broken, and the internal high-pressure organic solvent vapor was released before the internal temperature of the battery reached the flash point of the electrolyte solvent, preventing the battery from catching fire and exploding.

[0083] Example 4

[0084] 1.2 g of 4,4′-oxybis(benzenesulfonyl hydrazide) (main material), 0.5 g of zinc oxide (first additive), 0.1 g of triethanolamine (second additive), and 0.5 g of decabromodiphenyl ether (flame retardant) were mixed evenly and then pressed into tablets, which were sealed and packaged with a polypropylene sealing film to obtain a thermosensitive gas-generating structural member. When assembling an aluminum-shell lithium-ion battery, the thermosensitive gas-generating structural member was placed at a position between the tab and the safety valve and away from the liquid injection port to obtain an aluminum-shell lithium-ion battery containing the thermosensitive gas-generating structural member. Since the thermosensitive gas-generating composition placed inside the battery did not directly contact the electrolyte, it would not affect the electrochemical performance of the battery. This aluminum-shell lithium-ion battery was placed in an oven at 90 °C for 24 hours, and there was no change in the appearance of the battery. After this aluminum-shell lithium-ion battery was placed in an oven at 135 °C for 8 minutes, the explosion-proof film of the safety valve was broken, and the internal high-pressure organic solvent vapor was released before the internal temperature of the battery reached the flash point of the electrolyte solvent, preventing the battery from catching fire and exploding.

[0085] Example 5

[0086] Mix 2.3 g of azodicarbonamide (main material), 0.4 g of zinc stannate (first additive), and 0.8 g of magnesium hydroxide (flame retardant) evenly, then press them into tablets and seal them with polyethylene sealing film to obtain a thermosensitive gas-generating structural component. When assembling a soft-pack lithium-ion battery packaged with an aluminum-plastic film, place the thermosensitive gas-generating structural component on one of the larger surfaces on the side of the battery core to obtain a soft-pack lithium-ion battery containing the thermosensitive gas-generating structural component. Since the thermosensitive gas-generating composition placed inside the battery does not directly contact the electrolyte, it will not affect the electrochemical performance of the battery. Place this soft-pack battery in an oven at 90 °C for 24 hours, and there is no change in the appearance of the battery. Place this soft-pack lithium-ion battery in an oven at 140 °C for 2.5 min, and the aluminum-plastic film is broken, and the internal high-pressure organic solvent vapor is released before the temperature inside the battery reaches the flash point of the electrolyte solvent, preventing the battery from catching fire and exploding.

[0087] Example 6

[0088] Mix 3.7 g of diisopropyl azodicarboxylate (main material), 0.2 g of zirconium chloride (first additive), and 0.8 g of phosphorus nitride chloride (flame retardant) evenly, then press them into tablets and seal them with an aluminum-plastic packaging film to obtain a thermosensitive gas-generating structural component. When assembling a soft-pack lithium-ion battery packaged with an aluminum-plastic film, place the thermosensitive gas-generating structural component on one of the larger surfaces on the side of the battery core to obtain a soft-pack lithium-ion battery containing the thermosensitive gas-generating structural component. Since the thermosensitive gas-generating composition placed inside the battery does not directly contact the electrolyte, it will not affect the electrochemical performance of the battery. Place this soft-pack lithium-ion battery in an oven at 90 °C for 24 hours, and there is no change in the appearance of the battery. Place this soft-pack lithium-ion battery in an oven at 135 °C for 1.5 min, and the aluminum-plastic film is broken, that is, the internal high-pressure organic solvent vapor is released before the temperature inside the battery reaches the flash point of the electrolyte solvent, preventing the battery from catching fire or exploding.

[0089] Example 7

[0090] Mix 1.2 g of 3,3'-disulfonylhydrazide diphenyl sulfone (main material), 0.4 g of magnesium oxide (first additive), and 0.7 g of tetrachlorobisphenol A (flame retardant) evenly, then press them into tablets and seal them with polyethylene sealing film to obtain a thermosensitive gas-generating structural component. When assembling an aluminum-shell lithium-ion battery, place the thermosensitive gas-generating structural component at a position between the pole ear and the safety valve and away from the liquid injection port to obtain an aluminum-shell lithium-ion battery containing the thermosensitive gas-generating structural component. Since the thermosensitive gas-generating composition placed inside the battery does not directly contact the electrolyte, it will not affect the electrochemical performance of the battery. Place this aluminum-shell battery in an oven at 90 °C for 24 hours, and there is no change in the appearance of the battery. Place this aluminum-shell lithium-ion battery in an oven at 125 °C for 5 min, and the explosion-proof film of the safety valve is broken, that is, the internal high-pressure organic solvent vapor is released before the temperature inside the battery reaches the flash point of the electrolyte solvent, preventing the battery from catching fire or exploding.

[0091] Example 8

[0092] 4.2 g of N,N'-dimethyl-N,N'-dinitrosoterephthalamide (main material) and 0.3 g of triethanolamine (second additive) were mixed evenly and then pressed into tablets, which were sealed with an aluminum-plastic packaging film to obtain a temperature-sensitive gas-generating structural component. When assembling an aluminum-shell lithium-ion battery, the temperature-sensitive gas-generating structural component was placed at a position far from the liquid injection port between the tab and the safety valve to obtain an aluminum-shell lithium-ion battery containing the temperature-sensitive gas-generating structural component. Since the temperature-sensitive gas-generating composition placed inside the battery was not in direct contact with the electrolyte, it would not affect the electrochemical performance of the battery. After placing this aluminum-shell lithium-ion battery in an oven at 120 °C for 3 minutes, the explosion-proof film of the safety valve was broken through, that is, the internal high-pressure organic solvent vapor was released before the internal temperature of the battery reached the flash point of the electrolyte solvent, preventing the battery from catching fire or exploding.

[0093] Example 9

[0094] 3.0 g of N,N'-dimethyl-N,N'-dinitrosoterephthalamide (main material) was pressed into tablets, which were sealed with an aluminum-plastic packaging film to obtain a temperature-sensitive gas-generating material. When assembling an aluminum-shell lithium-ion battery, the temperature-sensitive gas-generating material was placed at a position far from the liquid injection port between the tab and the safety valve to obtain an aluminum-shell lithium-ion battery containing the temperature-sensitive gas-generating material. Since the temperature-sensitive gas-generating composition placed inside the battery was not in direct contact with the electrolyte, it would not affect the electrochemical performance of the battery. After placing this aluminum-shell lithium-ion battery in an oven at 120 °C for 6 minutes, the explosion-proof film of the safety valve was broken through, that is, the internal high-pressure organic solvent vapor was released before the internal temperature of the battery reached the flash point of the electrolyte solvent, preventing the battery from catching fire or exploding.

[0095] Comparative Example 1

[0096] A common soft-pack lithium-ion battery was placed in an oven at 120 °C. The outer packaging of the soft-pack lithium-ion battery bulged slightly and did not burst open. This shows that if the temperature-sensitive gas-generating structural component of the present invention is not added to a common soft-pack lithium-ion battery, potential hazards will continue to accumulate when the battery exceeds the normal operating temperature, and finally thermal runaway may occur, leading to fire or even explosion.

[0097] Comparative Example 2

[0098] A common aluminum-shell lithium-ion battery was placed in an oven at 120 °C. No obvious change was observed in the outer packaging of the battery. This shows that if the temperature-sensitive gas-generating structural component of the present invention is not added to a common aluminum-shell lithium-ion battery, although no obvious change is observed in the outer packaging of the battery, potential hazards will continue to accumulate when the battery exceeds the normal operating temperature, and finally thermal runaway may occur, leading to fire or even explosion.

[0099] Comparative Example 3

[0100] 0.8 g of azodicarbonamide (main material) was tableted and sealed with an aluminum-plastic packaging film to obtain a thermosensitive gas-generating structural component. During the assembly of an aluminum-shell lithium-ion battery, the thermosensitive gas-generating structural component was placed at a position between the tab and the safety valve, far from the liquid injection port, to obtain an aluminum-shell lithium-ion battery containing the thermosensitive gas-generating structural component. This aluminum-shell lithium-ion battery was placed in an oven at 150 °C for 5 h, and no obvious change was observed in the outer packaging of the battery. When the temperature was slowly raised to 205 °C, the explosion-proof film of the safety valve was broken through. When the internal temperature of the battery cell was higher than 140 °C, the separator had started to partially melt, forming a large-area short circuit. If the battery was in a fully charged state, it was already very dangerous at 150 °C, and thermal runaway, ignition, or even explosion might occur at any time.

[0101] Comparative Example 4

[0102] 1.2 g of barium azodicarboxylate (main material) was tableted and sealed with an aluminum-plastic packaging film to obtain a thermosensitive gas-generating structural component. During the assembly of an aluminum-shell lithium-ion battery, the thermosensitive gas-generating structural component was placed at a position between the tab and the safety valve, far from the liquid injection port, to obtain an aluminum-shell lithium-ion battery containing the thermosensitive gas-generating material. This aluminum-shell lithium-ion battery was placed in an oven at 150 °C for 5 h, and no obvious change was observed in the outer packaging of the battery. When the temperature was slowly raised to 265 °C, the explosion-proof film of the safety valve was broken through. When the internal temperature of the battery cell was higher than 140 °C, the separator had started to partially melt, forming a large-area short circuit. If the battery was in a fully charged state, it was already very dangerous at 150 °C, and thermal runaway, ignition, or even explosion might occur at any time.

[0103] Comparative Example 5

[0104] 2.0 g of 2,2'-azobis(2-methylpropionitrile) (main material) was tableted and sealed with an aluminum-plastic packaging film to obtain a thermosensitive gas-generating structural component. During the assembly of a soft-pack lithium-ion battery, the thermosensitive gas-generating structural component was placed on a larger surface on the side of the battery cell to obtain a soft-pack lithium-ion battery cell containing the thermosensitive gas-generating structural component. When this battery cell was dried at 90 °C before liquid injection, due to the low gas-generation temperature of the main material of the thermosensitive gas-generating structural component, the aluminum-plastic packaging film had bulged, preventing the battery cell from entering the next process for normal liquid injection.

[0105] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A temperature-sensitive gas-generating composition, wherein: The temperature-sensitive gas-generating composition includes a main material; or the temperature-sensitive gas-generating composition includes a main material and an additive; The host material is selected from at least one of diazoaminobenzene, azodicarbonamide, barium azodicarboxylate, azodicarbonate, diisopropyl azodicarboxylate, N,N′-dinitrosopentamethylenetetramine, N,N′-dimethyl N,N′-dinitrosoterephthalamide, trinitrosotrimethylenetriamine, 4,4′-oxybisbenzenesulfonylhydrazide, 3,3′-disulfonylhydrazide diphenyl sulfone, benzenesulfonylhydrazide, p-toluenesulfonylhydrazide, 2,4-toluenedisulfonylhydrazide and p-(N-methoxyformamido)benzenesulfonylhydrazide; The gas generation temperature of the temperature-sensitive gas generating composition is 100-140°C.

2. The temperature-sensitive gas generating composition according to claim 1, wherein The additive is selected from at least one of a first additive, a second additive and a flame retardant; the first additive is an additive capable of reducing the gas generation temperature of the main material; and the second additive is an additive capable of absorbing hydrogen fluoride. Preferably, the first additive is selected from at least one of zinc oxide, zinc chloride, zinc stannate, zinc acetate, zirconium chloride, magnesium oxide, magnesium chloride, titanium dioxide, iron powder, organic acid salt, urea, biuret, triuret, cyanuric acid, ethanolamine, malonyl urea, semicarbazide, organic acid and borax; And / or, the second additive is selected from at least one of triethanolamine, sodium carbonate, potassium carbonate, zinc carbonate, aluminum hydroxide and magnesium hydroxide.

3. The temperature-sensitive gas generating composition according to claim 2, wherein The mass of the main material accounts for 50-100 wt % of the total mass of the temperature-sensitive gas generating composition. Preferably, the mass of the first additive accounts for 0-50wt% of the total mass of the temperature-sensitive gas generating composition; the mass of the second additive accounts for 0-10wt% of the total mass of the temperature-sensitive gas generating composition; the mass of the flame retardant accounts for 0-50wt% of the total mass of the temperature-sensitive gas generating composition. Preferably, the total mass of the first additive, the second additive and the flame retardant accounts for 1-50 wt % of the total mass of the temperature-sensitive gas generating composition.

4. The temperature-sensitive gas generating composition according to claim 2, wherein The flame retardant is selected from at least one of an inorganic flame retardant, a halogen flame retardant, a phosphorus flame retardant, a silicon flame retardant or an intumescent flame retardant.

5. A temperature-sensitive gas-generating structural component, wherein: The temperature-sensitive gas-generating structural component comprises the temperature-sensitive gas-generating composition according to any one of claims 1 to 4 and a packaging film, wherein the packaging film is encapsulated on the outer surface of the temperature-sensitive gas-generating composition.

6. The temperature-sensitive gas-generating structural member according to claim 5, wherein: The packaging film is selected from at least one of polyethylene heat-sealing film, polypropylene heat-sealing film, polyester heat-sealing film or aluminum-plastic packaging film; And / or, the packaging film has a thickness of 10-100 μm. Preferably, the temperature-sensitive gas-generating structural component is placed in a lithium-ion battery.

7. A lithium-ion battery, comprising the temperature-sensitive gas-generating structural component according to claim 5 or 6, wherein the temperature-sensitive gas-generating structural component is arranged between a shell and a battery cell of the lithium-ion battery. Preferably, the outer shell is a hard shell or an aluminum-plastic film; the hard shell is, for example, a plastic shell or an aluminum shell.

8. The lithium ion battery according to claim 7, wherein When the lithium-ion battery is a hard-shell lithium-ion battery, the temperature-sensitive gas-generating structural component is placed between the battery cell and the hard shell, for example, it can be placed near the pressure relief valve, near the safety valve, between the pole ear and the safety valve away from the liquid injection port, between the pole ear and the pressure relief valve away from the liquid injection port, between the two pole ears, or at the inner bottom of the hard shell.

9. The lithium ion battery according to claim 7, wherein When the lithium-ion battery is a soft-pack lithium-ion battery, the temperature-sensitive gas-generating structural component is placed between the battery cell and the aluminum-plastic film, for example, it can be placed near the second sealing edge of the aluminum-plastic film, between the two tabs, or on one or two surfaces with a larger area on the side of the battery cell.

10. A method for improving the safety performance of a lithium-ion battery, the method comprising: During the assembly process of the lithium-ion battery, the temperature-sensitive gas-generating structural member according to claim 5 or 6 is encapsulated between the outer shell and the battery cell of the lithium-ion battery.

Images