Battery safety liquid and preparation method thereof, lithium ion battery and electric device

Abstract

The invention discloses a battery safety liquid and a preparation method thereof, a lithium ion battery and an electric device. The battery safety liquid comprises a solution and oxide particles, the particle size variation coefficient of the oxide particles is phi, phi is larger than or equal to 0 and smaller than or equal to 0.1, and the particle size variation coefficient phi is equal to the ratio of the average variance of the particle sizes of the particles to the average value of the particle sizes of the particles. The oxide particles are particles with relatively high particle size distribution uniformity, and in the later use period of the battery, after the battery safety liquid containing the oxide particles is added into an electrolyte of the battery, the viscosity of the electrolyte can be improved, the fluidity of the electrolyte can be reduced, the flow of gas generated by an electrode due to long-term use of the battery is reduced, and the extrusion deformation of the gas to a shell is reduced; and meanwhile, the viscosity of the electrolyte is increased, the fluidity is reduced, the mass transfer resistance is increased, and the electric conductivity of the battery cell is reduced, so that the thermal runaway risk of the battery cell is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and particularly relates to a battery safety liquid and its preparation method, a lithium-ion battery, and an electrical device. Background Art

[0002] Lithium batteries have good cycling performance and high energy density, and are widely used in the new energy field.

[0003] However, during the use of lithium batteries, in the later stage of battery use, as the internal pressure of the hard-shell battery increases, the interaction stress generated by the expansion force makes the hard shell prone to local embrittlement and reduced strength, increasing the risks of impact short circuit and thermal runaway. Summary of the Invention

[0004] The present application is made in view of the above problems, and its purpose is to provide a battery safety liquid to reduce the risks of impact short circuit and thermal runaway in the later stage of lithium-ion battery use.

[0005] To achieve the above purpose, the embodiments of the present application provide a battery safety liquid and its preparation method, a lithium-ion battery, and an electrical device.

[0006] In a first aspect, the embodiments of the present application propose a battery safety liquid, including a solution and oxide particles, wherein the coefficient of variation of the particle size of the oxide particles is φ, 0 ≤ φ ≤ 0.1, and the coefficient of variation of the particle size φ = average variance of the particle size of the particles / average value of the particle size of the particles.

[0007] Thus, in the technical solution of the embodiments of the present application, by adding oxide particles to the battery safety liquid, with the coefficient of variation of the particle size of the oxide particles being φ, 0 ≤ φ ≤ 0.1, the oxide particles are particles with a relatively high uniformity of particle size distribution. As a result, in the later stage of battery use, when the battery safety liquid containing oxide particles is added to the electrolyte of the battery, it can increase the viscosity of the electrolyte, reduce the fluidity of the electrolyte, reduce the flow of gas generated by the electrodes during long-term use of the battery, reduce the extrusion deformation of the gas on the housing, and further reduce the risk of impact short circuit of the battery. At the same time, since the viscosity of the electrolyte increases, the fluidity becomes smaller, the mass transfer resistance increases, and the conductivity of the battery cell decreases, thereby reducing the risk of thermal runaway of the battery cell.

[0008] The coefficient of variation of the particle size characterizes the uniformity of the particle size distribution of the oxide particles. The smaller the coefficient of variation of the particle size, the more uniform the particle size distribution.

[0009] In any implementation manner, 0 ≤ φ ≤ 0.05. When the coefficient of variation of the particle size of the oxide particles is in the range of 0 to 0.05, the particle size distribution of the oxide particles is more uniform, and the effect of increasing the viscosity of the electrolyte is better, further reducing the risks of impact short circuit and thermal runaway of the battery.

[0010] In any embodiment, the oxide particles include, but are not limited to, at least one of titanium dioxide, aluminum oxide, manganese dioxide, nickel oxide, cobalt oxide, iron oxide, zinc oxide, and silicon dioxide. By using at least one of the above oxide particles, while increasing the viscosity of the electrolyte, the probability of reaction between the oxide particles and the electrolyte can be reduced, further reducing the risk of impact short circuit and thermal runaway of the battery. It should be noted that in the embodiments of the present application, when the oxide particles include silicon dioxide, due to the inertness of silicon dioxide, when the battery is subjected to impact and vibration, the non-Newtonian fluid electrolyte can absorb greater impact momentum and energy, reduce the damage to the SEI film and the electrode structure, reduce the irreversible reaction rate, and thus reduce the risk of further expansion caused by battery gas generation.

[0011] In any embodiment, the particle size of the oxide particles is R, where 0.001 μm ≤ R ≤ 100 μm. When the particle size of the oxide particles is within this range, the viscosity of the electrolyte can be increased, the fluidity of the electrolyte can be reduced, and the flow of gas generated by the electrodes during long-term use of the battery can be reduced, thereby reducing the risk of battery expansion; optionally, 0.1 μm ≤ R ≤ 1 μm can further reduce the fluidity of the electrolyte and the flow of gas generated by the electrodes during long-term use of the battery, thereby reducing the risk of battery expansion.

[0012] In any embodiment, the mass ratio of the oxide particles in the battery safety liquid is A1, where 20% ≤ A1 ≤ 90%. When the mass ratio of the oxide particles in the battery safety liquid is within this range, the mass ratio of the oxide particles can be increased. Thus, when the battery safety liquid is added to the electrolyte in the later stage of battery use, while increasing the viscosity of the electrolyte, the probability of reaction between the oxide particles and the electrolyte can be reduced, and the risk of impact short circuit and thermal runaway of the battery can be reduced. Optionally, 40% ≤ A1 ≤ 80% can further reduce the probability of reaction between the oxide particles and the electrolyte while increasing the viscosity of the electrolyte, and reduce the risk of impact short circuit and thermal runaway of the battery.

[0013] In any embodiment, the solution includes a lithium salt solution, where:

[0014] The solute of the lithium salt solution includes, but is not limited to, at least one of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, and lithium hexafluoroarsenate. By using at least one of the above solutes, the safety performance of the electrolyte can be improved; and / or,

[0015] The solvent of the lithium salt solution includes, but is not limited to, at least one of ethylene carbonate, diethyl carbonate, dimethyl carbonate, and ethyl methyl carbonate. By using at least one of the above solvents, the safety performance of the electrolyte can be improved.

[0016] Second aspect, an embodiment of the present application provides a method for preparing a battery safety liquid for preparing the battery safety liquid of the first aspect of the present application, including the following steps:

[0017] Provide oxide particles with a coefficient of variation in particle size of 0 ≤ φ ≤ 0.1;

[0018] Mix the oxide particles with a solution to obtain a battery safety liquid.

[0019] By mixing oxide particles with a coefficient of variation in particle size of 0 ≤ φ ≤ 0.1 with a solution, a battery safety liquid can be obtained. When the battery is in the later stage of use, the battery safety liquid containing oxide particles is added to the electrolyte of the battery, which can increase the viscosity of the electrolyte, thereby reducing the risk of impact short circuit of the battery. At the same time, due to the increase in the viscosity of the electrolyte, the fluidity becomes smaller, the mass transfer resistance increases, and the conductivity of the battery cell decreases, thereby reducing the risk of thermal runaway of the battery cell.

[0020] It should be noted that in the embodiments of the present application, the oxide particles with a coefficient of variation in particle size of 0 ≤ φ ≤ 0.1 can be purchased or prepared by oneself, as long as the coefficient of variation in particle size of 0 ≤ φ ≤ 0.1 is satisfied.

[0021] In any implementation manner, the step of providing oxide particles with a coefficient of variation in particle size of 0 ≤ φ ≤ 0.1 includes: preparing oxide particles by the Stober method. The oxide particles prepared by the Stober method have a more uniform particle size distribution and a smaller coefficient of variation in particle size, which can further increase the viscosity of the electrolyte, thereby reducing the risk of impact short circuit of the battery. At the same time, due to the increase in the viscosity of the electrolyte, the fluidity becomes smaller, the mass transfer resistance increases, and the conductivity of the battery cell decreases, thereby reducing the risk of thermal runaway of the battery cell.

[0022] In the embodiments of the present application, the oxide particles prepared by the Stober method can be prepared by the following steps, taking the preparation of silica particles as an example: Mix 23.5 mL of secondary distilled water, 63.3 mL of isopropanol, and 13 mL of ammonia water (25 - 28%) and perform an oil bath at 35°C. Then, add 0.6 mL of 99% TEOS (tetraethyl orthosilicate) dropwise and stir vigorously for 30 min to obtain a silica sphere seed solution. Then, add 5 mL of TEOS dropwise to the silica sphere seed solution and continue to react for 2 hours, and then centrifuge and dry to obtain silica particles with a coefficient of variation in particle size of 0 ≤ φ ≤ 0.1.

[0023] In any implementation manner, the step of mixing the oxide particles with a lithium salt solution to obtain a battery safety liquid includes:

[0024] The oxide particles are ultrasonically mixed with the lithium salt solution to obtain the battery safety liquid. Ultrasonic mixing can improve the uniformity of the mixture of the oxide particles and the lithium salt solution. When added to the electrolyte, it can increase the viscosity of the electrolyte, thereby reducing the risk of impact short circuit of the battery. At the same time, due to the increase in the viscosity of the electrolyte, the fluidity becomes smaller, the mass transfer resistance increases, and the conductivity of the battery cell decreases, thus reducing the risk of thermal runaway of the battery cell.

[0025] In a third aspect, an embodiment of the present application provides a lithium-ion battery, including an electrolyte and the battery safety liquid of the first aspect of the present application, or the battery safety liquid prepared by the preparation method of the battery safety liquid of the second aspect of the present application.

[0026] It should be noted that in the embodiments of the present application, the electrolyte and the battery safety liquid can have two states. In the early stage of battery use, the electrolyte and the battery safety liquid exist independently and are stored separately in different battery spaces. In the later stage of battery use, through a triggering device, the release of the battery safety liquid can be triggered, and the battery safety liquid is released into the electrolyte. Under the driving force of the gas flow generated by the battery expansion, the battery safety liquid is mixed with the electrolyte, so that the battery safety liquid and the electrolyte are in a mixed state in the same battery space. Among them, the triggering device can be released by a control valve. When the internal pressure exceeds the preset value, the control valve is manually or automatically opened to release the safety liquid into the electrolyte. It can also be released by the rupture of a pressure membrane. When the internal pressure exceeds the preset value, the pressure membrane automatically ruptures to release the safety liquid into the electrolyte.

[0027] In any implementation manner, the mass fraction of the electrolyte is w1, the mass fraction of the battery safety liquid is w2, and the mass fraction of the oxide particles in the battery safety liquid is w3, where:

[0028] 5% ≤ w3 / (w1 + w2) ≤ 35%. At this mass ratio, when all the battery safety liquid is mixed with the electrolyte, the electrolyte changes from a Newtonian fluid to a non-Newtonian fluid, and the viscosity of the electrolyte increases significantly, thereby reducing the risk of impact short circuit of the battery. At the same time, due to the increase in the viscosity of the electrolyte, the fluidity becomes smaller, the mass transfer resistance increases, and the conductivity of the battery cell decreases, thus reducing the risk of thermal runaway of the battery cell. Optionally, 10% ≤ w3 / (w1 + w2) ≤ 30% can further change the electrolyte from a Newtonian fluid to a non-Newtonian fluid, and the viscosity of the electrolyte increases significantly, thereby reducing the risk of impact short circuit of the battery. At the same time, due to the increase in the viscosity of the electrolyte, the fluidity becomes smaller, the mass transfer resistance increases, and the conductivity of the battery cell decreases, thus reducing the risk of thermal runaway of the battery cell.

[0029] In any implementation manner, the viscosity of the electrolyte is V1, and the viscosity of the mixture of the battery safety liquid and the electrolyte is V2, where:

[0030] 2 ≤ V2:V1 ≤ 10, that is, when the battery safety liquid is mixed with the electrolyte, the viscosity of the electrolyte increases by 2 to 15 times compared to the initial value before mixing. The electrolyte changes from a Newtonian fluid to a non-Newtonian fluid, and the viscosity of the electrolyte increases significantly, thereby reducing the risk of impact short circuit of the battery. At the same time, due to the increase in the viscosity of the electrolyte, the fluidity becomes smaller, the mass transfer resistance increases, and the conductivity of the battery cell decreases, thus reducing the risk of thermal runaway of the battery cell; optionally, 5 ≤ V2:V1 ≤ 10, which can further change the electrolyte from a Newtonian fluid to a non-Newtonian fluid, and the viscosity of the electrolyte increases significantly, thereby reducing the risk of impact short circuit of the battery. At the same time, due to the increase in the viscosity of the electrolyte, the fluidity becomes smaller, the mass transfer resistance increases, and the conductivity of the battery cell decreases, thus reducing the risk of thermal runaway of the battery cell.

[0031] In any implementation manner, the electrolyte includes a lithium salt electrolyte.

[0032] In any implementation manner, the lithium salt electrolyte includes a lithium salt and a solvent, wherein:

[0033] The lithium salt includes but is not limited to at least one of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, and lithium hexafluoroarsenate. By using at least one of the above solutes, the safety performance of the electrolyte can be improved after adding the battery safety liquid; and / or,

[0034] The solvent includes but is not limited to at least one of ethylene carbonate, diethyl carbonate, dimethyl carbonate, and ethyl methyl carbonate. By using at least one of the above solutes, the safety performance of the electrolyte can be improved after adding the battery safety liquid.

[0035] In a fourth aspect, an electrical device according to an embodiment of the present application includes the battery according to the fourth aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a schematic diagram of a secondary battery according to an embodiment of the present application.

[0037] Figure 2 is Figure 1 the exploded view of the secondary battery according to an embodiment of the present application shown in

[0038] Figure 3 is a schematic diagram of a battery module according to an embodiment of the present application.

[0039] Figure 4 is a schematic diagram of a battery pack according to an embodiment of the present application.

[0040] Figure 5 is Figure 4 the exploded view of the battery pack according to an embodiment of the present application shown in

[0041] Figure 6It is a schematic diagram of an electrical device using a secondary battery as a power source according to an embodiment of the present application.

[0042] Explanation of reference numerals:

[0043] 1 Battery pack; 2 Upper box body; 3 Lower box body; 4 Battery module; 5 Secondary battery; 51 Housing; 52 Electrode assembly; 53 Top cover assembly Detailed implementation manners

[0044] Hereinafter, embodiments of the battery safety liquid, the preparation method of the battery safety liquid, the battery and the electrical device of the present application are specifically disclosed. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually identical structures are omitted. This is to avoid the following descriptions from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following descriptions are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter recited in the claims.

[0045] The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a specific range. The range defined in this way can include or not include the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 - 120 and 80 - 110 are listed for a specific parameter, ranges of 60 - 110 and 80 - 120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, the following ranges are all contemplated: 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5. In the embodiments of the present application, unless otherwise specified, the numerical range "a - b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" have been fully listed herein, and "0 - 5" is only an abbreviated representation of these numerical combinations. In addition, when it is stated that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0046] If there is no special instruction, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0047] If there is no special instruction, all technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0048] Unless otherwise specified, all steps of this application can be carried out sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) carried out sequentially, or may also include steps (b) and (a) carried out sequentially. For example, when it is mentioned that the method may further include step (c), it means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or may also include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0049] Lithium batteries have good cycling performance and high energy density, and are widely used in the new energy field.

[0050] However, during the use of lithium batteries, in the later stage of battery use, as the internal pressure of the hard shell battery increases, the interaction stress generated by the expansion force makes the hard shell prone to local embrittlement and reduced strength, increasing the risks of impact short circuit and thermal runaway.

[0051] Therefore, research on reducing the risks of impact short circuit and thermal runaway in the later stage of lithium-ion battery use has emerged in an endless stream. For example, by setting a spray valve, when the pressure increases to the bursting valve threshold, the spray valve is opened to relieve pressure, reducing the internal pressure of the battery. At the same time, the vent hole of the pressure relief structure is designed as a sealed one-way valve to prevent air from flowing back into the battery core. However, this method has a complex one-way valve, with potential risks such as insufficient sealing and air flowing back into the battery core, and the risk of failure of the spring and gasket structure. It cannot completely prevent the electrolyte from leaking out with the airflow, causing corrosion and damage to the outer shell and battery structure. Moreover, with the interaction stress generated by the expansion force during the use of the battery core, the hard shell shows local embrittlement and reduced strength, further increasing the risks of impact short circuit and thermal runaway.

[0052] Surprisingly, by triggering the safety liquid release device in the later stage when the battery gas generation is severe, the safety liquid is released from the container into the electrolyte. Under the cyclic drive of the expansion force, the safety liquid is mixed with the electrolyte, reducing the battery gas generation amount while improving the overall impact resistance of the battery, and enhancing the battery's ability to resist impact runaway and thermal failure risks.

[0053] Based on this, the present application provides a battery safety liquid, its preparation method, a lithium-ion battery, and an electrical device using the same.

[0054] In a first aspect, an embodiment of the present application proposes a battery safety liquid, including a solution and oxide particles, wherein the coefficient of variation of the particle size of the oxide particles is φ, 0 ≤ φ ≤ 0.1, and the coefficient of variation of the particle size φ = the average variance of the particle size of the particles / the average value of the particle size of the particles.

[0055] Thus, in the technical solution of the embodiment of the present application, by adding oxide particles to the battery safety liquid, the coefficient of variation of the particle size of the oxide particles is φ, where 0 ≤ φ ≤ 0.1, so that the oxide particles have a relatively high uniformity in particle size distribution. As a result, in the later stage of battery use, when the battery safety liquid containing oxide particles is added to the electrolyte of the battery, the viscosity of the electrolyte can be increased, the fluidity of the electrolyte can be reduced, the flow of gas generated by the electrodes during long-term battery use can be reduced, the extrusion deformation of the housing caused by the gas can be reduced, and thus the risk of impact short circuit of the battery can be reduced. At the same time, due to the increase in the viscosity of the electrolyte, the decrease in fluidity, the increase in mass transfer resistance, and the decrease in the conductivity of the battery cell, the risk of thermal runaway of the battery cell can be reduced. The value of the coefficient of variation φ of the particle size of the oxide particles can be 0, 0.005, 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.045, 0.05, 0.055, 0.06, 0.065, 0.07, 0.075, 0.08, 0.085, 0.09, 0.095 or 0.1.

[0056] It should be noted that in the embodiment of the present application, the average variance of the particle size of the particles refers to the statistical variance of the diameters of the sampled samples, and the average value of the particle size of the particles refers to the statistical average value of the sampled samples. The particle size measurement method of the particles is sampling microscopy imaging statistics. The coefficient of variation of the particle size characterizes the uniformity of the particle size distribution of the oxide particles. The smaller the coefficient of variation of the particle size, the more uniform the particle size distribution.

[0057] In any implementation, 0 ≤ φ ≤ 0.05. When the coefficient of variation of the particle size of the oxide particles is in the range of 0 to 0.05, the particle size distribution of the oxide particles is more uniform, and the effect of increasing the viscosity of the electrolyte is better, further reducing the risk of impact short circuit and thermal runaway of the battery.

[0058] In any implementation, the oxide particles include but are not limited to at least one of titanium dioxide, aluminum oxide, manganese dioxide, nickel oxide, cobalt oxide, iron oxide, zinc oxide, and silicon dioxide. By using at least one of the above oxide particles, the probability of reaction between the oxide particles and the electrolyte can be reduced while increasing the viscosity of the electrolyte, further reducing the risk of impact short circuit and thermal runaway of the battery. It should be noted that in the embodiment of the present application, when the oxide particles include silicon dioxide, due to the inertness of silicon dioxide, the probability of reaction with the electrolyte can be further reduced. At the same time, the gaps between the silicon dioxide particles can accommodate the gas generated by the electrodes during long-term battery use. By increasing the viscosity of the electrolyte, the fluidity of the electrolyte is reduced, and the flow of gas is reduced, thereby reducing the risk of further expansion of the battery.

[0059] In any embodiment, the particle size of the oxide particles is R, where 0.001 μm ≤ R ≤ 100 μm. When the particle size of the oxide particles is within this range, the viscosity of the electrolyte can be increased, the fluidity of the electrolyte can be reduced, and the flow of gas generated by the electrodes during long-term use of the battery can be reduced, thereby reducing the risk of battery swelling. The value of the particle size R of the oxide particles can be 0.001 μm, 0.05 μm, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 2.0 μm, 5.0 μm, 8.0 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, or 100 μm; optionally, 0.1 μm ≤ R ≤ 1 μm, which can further reduce the fluidity of the electrolyte and the flow of gas generated by the electrodes during long-term use of the battery, thereby reducing the risk of battery swelling.

[0060] It should be noted that the particle size measurement method can be sampling microscopy measurement and statistics.

[0061] In any embodiment, the mass ratio of the oxide particles in the battery safety liquid is A1, where: 20% ≤ A1 ≤ 90%. When the mass ratio of the oxide particles in the battery safety liquid is within this range, the mass ratio of the oxide particles can be increased. Thus, when the battery safety liquid is added to the electrolyte in the later stage of battery use, while increasing the viscosity of the electrolyte, the probability of the oxide particles reacting with the electrolyte can be reduced, and the risks of impact short circuit and thermal runaway of the battery can be reduced. The value of the mass ratio A1 of the oxide particles in the battery safety liquid can be 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90%. Optionally, 40% ≤ A1 ≤ 80%, which can further reduce the probability of the oxide particles reacting with the electrolyte while increasing the viscosity of the electrolyte, and reduce the risks of impact short circuit and thermal runaway of the battery.

[0062] In any embodiment, the solution includes a lithium salt solution, where:

[0063] In any embodiment, the solution includes a lithium salt solution, where the solute of the lithium salt solution includes but is not limited to at least one of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, and lithium hexafluoroarsenate. Using at least one of the above solutes can improve the safety performance of the electrolyte.

[0064] In any embodiment, the solution includes a lithium salt solution, and the solvent of the lithium salt solution includes, but is not limited to, at least one of ethylene carbonate, diethyl carbonate, dimethyl carbonate, and ethyl methyl carbonate. By using at least one of the above solvents, the safety performance of the electrolyte can be improved.

[0065] It should be noted that the selection of the above lithium salt and solvent can be set simultaneously or separately. When set simultaneously, the effect of improving the safety performance of the electrolyte is better after adding the battery safety liquid.

[0066] In a second aspect, an embodiment of the present application provides a method for preparing a battery safety liquid for preparing the battery safety liquid in the first aspect of the present application, including the following steps:

[0067] Provide oxide particles with a particle size coefficient of variation 0 ≤ φ ≤ 0.1;

[0068] Mix the oxide particles with the solution to obtain the battery safety liquid.

[0069] By mixing oxide particles with a particle size coefficient of variation 0 ≤ φ ≤ 0.1 with the solution, a battery safety liquid can be obtained. When the battery is in the later stage of use, adding the battery safety liquid containing oxide particles to the electrolyte of the battery can increase the viscosity of the electrolyte, thereby reducing the risk of impact short circuit of the battery. At the same time, due to the increase in the viscosity of the electrolyte, the fluidity becomes smaller, the mass transfer resistance increases, and the conductivity of the battery cell decreases, thereby reducing the risk of thermal runaway of the battery cell.

[0070] It should be noted that in the embodiments of the present application, the oxide particles with a particle size coefficient of variation 0 ≤ φ ≤ 0.1 can be purchased or prepared by oneself, as long as the particle size coefficient of variation 0 ≤ φ ≤ 0.1 is satisfied.

[0071] In any embodiment, the step of providing oxide particles with a particle size coefficient of variation 0 ≤ φ ≤ 0.1 includes: preparing oxide particles by the Stober method. The oxide particles prepared by the Stober method have a more uniform particle size distribution and a smaller particle size coefficient of variation, which can further increase the viscosity of the electrolyte, thereby reducing the risk of impact short circuit of the battery. At the same time, due to the increase in the viscosity of the electrolyte, the fluidity becomes smaller, the mass transfer resistance increases, and the conductivity of the battery cell decreases, thereby reducing the risk of thermal runaway of the battery cell.

[0072] In the embodiments of the present application, the following steps can be adopted to prepare oxide particles by the Stober method. Taking the preparation of silica particles as an example, 23.5 mL of secondary distilled water, 63.3 mL of isopropanol, and 13 mL of ammonia water (25-28%) are mixed and placed in an oil bath at 35°C. Then, 0.6 mL of 99% TEOS (tetraethyl orthosilicate) is added dropwise, and the mixture is vigorously stirred and reacted for 30 min to obtain a silica sphere seed solution. Then, 5 mL of TEOS is added dropwise to the silica sphere seed solution, and the reaction continues for 2 hours. After centrifugation and drying, silica particles with a coefficient of variation of particle size 0 ≤ φ ≤ 0.1 can be obtained.

[0073] In any implementation manner, the step of mixing the oxide particles with a lithium salt solution to obtain a battery safety liquid includes:

[0074] The oxide particles are ultrasonically mixed with a lithium salt solution to obtain a battery safety liquid. Ultrasonic mixing can improve the uniformity of the mixing of the oxide particles and the lithium salt solution. When added to the electrolyte, it can increase the viscosity of the electrolyte, thereby reducing the risk of impact short circuit of the battery. At the same time, due to the increase in the viscosity of the electrolyte, the fluidity becomes smaller, the mass transfer resistance increases, and the conductivity of the battery cell decreases, thus reducing the risk of thermal runaway of the battery cell.

[0075] In a third aspect, an embodiment of the present application provides a lithium-ion battery, including an electrolyte and the battery safety liquid of the first aspect of the present application, or the battery safety liquid prepared by the preparation method of the battery safety liquid of the second aspect of the present application.

[0076] It should be noted that in the embodiments of the present application, the electrolyte and the battery safety liquid can exist in two states. In the early stage of battery use, the electrolyte and the battery safety liquid exist independently and are stored separately in different battery spaces. In the later stage of battery use, through a triggering device, the release of the battery safety liquid can be triggered, and the battery safety liquid is released into the electrolyte. Under the driving force of the gas flow generated by the battery expansion, the battery safety liquid is mixed with the electrolyte, so that the battery safety liquid and the electrolyte are in a mixed state in the same battery space. Among them, the triggering device can be released by a control valve. When the internal pressure exceeds a preset value, the control valve is manually or automatically opened to release the safety liquid into the electrolyte. It can also be released by the rupture of a pressure film. When the internal pressure exceeds a preset value, the pressure film automatically ruptures to release the safety liquid into the electrolyte.

[0077] In any embodiment, the mass fraction of the electrolyte is w1, the mass fraction of the battery safety liquid is w2, and the mass fraction of the oxide particles in the battery safety liquid is w3, where: 5% ≤ w3 / (w1 + w2) ≤ 35%. At this mass ratio, when all the battery safety liquid is mixed with the electrolyte, the electrolyte changes from a Newtonian fluid to a non-Newtonian fluid, and the viscosity of the electrolyte increases significantly, thereby reducing the risk of impact short circuit of the battery. At the same time, due to the increase in the viscosity of the electrolyte, the fluidity becomes smaller, the mass transfer resistance increases, and the conductivity of the battery cell decreases, thus reducing the risk of thermal runaway of the battery cell. The value of w3 / (w1 + w2) can be 5%, 10%, 15%, 20%, 25%, 30%, or 35%; optionally, 10% ≤ w3 / (w1 + w2) ≤ 30%, which can further change the electrolyte from a Newtonian fluid to a non-Newtonian fluid, and the viscosity of the electrolyte increases significantly, thereby reducing the risk of impact short circuit of the battery. At the same time, due to the increase in the viscosity of the electrolyte, the fluidity becomes smaller, the mass transfer resistance increases, and the conductivity of the battery cell decreases, thus reducing the risk of thermal runaway of the battery cell. It should be noted that when w3 / (w1 + w2) exceeds 80%, the effect on the viscosity of the electrolyte becomes smaller, and the viscosity of the electrolyte gradually approaches the initial viscosity.

[0078] In any embodiment, the viscosity of the electrolyte is V1, and the viscosity of the mixture of the battery safety liquid and the electrolyte is V2, where: 2 ≤ V2:V1 ≤ 10, that is, when the battery safety liquid is mixed with the electrolyte, the viscosity of the electrolyte increases by 2 to 15 times compared with the initial value before mixing, changing the electrolyte from a Newtonian fluid to a non-Newtonian fluid, and the viscosity of the electrolyte increases significantly, thereby reducing the risk of impact short circuit of the battery. At the same time, due to the increase in the viscosity of the electrolyte, the fluidity becomes smaller, the mass transfer resistance increases, and the conductivity of the battery cell decreases, thus reducing the risk of thermal runaway of the battery cell. The value of V2:V1 can be 2, 3, 4, 5, 6, 7, 8, 9, or 10; optionally, 5 ≤ V2:V1 ≤ 10, which can further change the electrolyte from a Newtonian fluid to a non-Newtonian fluid, and the viscosity of the electrolyte increases significantly, thereby reducing the risk of impact short circuit of the battery. At the same time, due to the increase in the viscosity of the electrolyte, the fluidity becomes smaller, the mass transfer resistance increases, and the conductivity of the battery cell decreases, thus reducing the risk of thermal runaway of the battery cell.

[0079] In any embodiment, the electrolyte includes a lithium salt electrolyte.

[0080] In any embodiment, the lithium salt electrolyte includes a lithium salt and a solvent, where the lithium salt includes but is not limited to at least one of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, and lithium hexafluoroarsenate. By using at least one of the above solutes, the safety performance of the electrolyte can be improved after adding the battery safety liquid.

[0081] In any embodiment, the lithium salt electrolyte includes a lithium salt and a solvent. Among them, the solvent includes, but is not limited to, at least one of ethylene carbonate, diethyl carbonate, dimethyl carbonate, and ethyl methyl carbonate. By using at least one of the above solutes, the safety performance of the electrolyte can be improved after adding the battery safety liquid.

[0082] It should be noted that the selection of the above lithium salt and solvent can be set simultaneously or separately. When set simultaneously, the effect of improving the safety performance of the electrolyte after adding the battery safety liquid is better.

[0083] In any embodiment, the battery includes a primary battery or a secondary battery.

[0084] In one embodiment of the present application, a secondary battery is provided. Generally, a secondary battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator. During the charge and discharge process of the battery, active ions are embedded and extracted back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays a role in conducting ions between the positive electrode sheet and the negative electrode sheet. The separator is disposed between the positive electrode sheet and the negative electrode sheet, mainly playing a role in reducing the probability of short circuit between the positive and negative electrodes, and at the same time allowing ions to pass through.

[0085] The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector.

[0086] As an example, the positive electrode current collector has two surfaces opposite to each other in its own thickness direction, and the positive electrode film layer is provided on either or both of the two opposite surfaces of the positive electrode current collector.

[0087] In some embodiments, the positive electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, aluminum foil can be used. The composite current collector can include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0088] In some embodiments, the positive electrode active material may be a positive electrode active material for lithium ion batteries known in the art. As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO 2 ), lithium nickel oxide (such as LiNiO 2 ), lithium manganese oxide (such as LiMnO 2 , LiMn 2 O 4 ), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 (which may also be abbreviated as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (which may also be abbreviated as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O 2 (which may also be abbreviated as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (which may also be abbreviated as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O 2 (which may also be abbreviated as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O 2 ) and their modified compounds, etc. Examples of lithium-containing phosphates with an olivine structure may include, but are not limited to, lithium iron phosphate (such as LiFePO 4 (which may also be abbreviated as LFP)), composite materials of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), composite materials of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and composite materials of lithium manganese iron phosphate and carbon.

[0089] In some embodiments, the positive electrode film layer may further optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0090] In some embodiments, the positive electrode film layer may further optionally include a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0091] In some embodiments, the positive electrode sheet may be prepared by the following method: dispersing the above-mentioned components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder, and any other components, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on the positive electrode current collector, and after processes such as drying and cold pressing, the positive electrode sheet can be obtained.

[0092] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector, and the negative electrode film layer includes a negative electrode active material.

[0093] As an example, the negative electrode current collector has two surfaces opposite to each other in its own thickness direction, and the negative electrode film layer is provided on either or both of the two opposite surfaces of the negative electrode current collector.

[0094] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, copper foil may be used. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0095] In some embodiments, the negative electrode active material can be the negative electrode active material for batteries well-known in the art. As an example, the negative electrode active material can include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. The silicon-based materials can be selected from at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based materials can be selected from at least one of elemental tin, tin oxides, and tin alloys. However, the present application is not limited to these materials, and other conventional materials that can be used as the negative electrode active material of the battery can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0096] In some embodiments, the negative electrode film layer may optionally further include a binder. The binder can be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0097] In some embodiments, the negative electrode film layer may optionally further include a conductive agent. The conductive agent can be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0098] In some embodiments, the negative electrode film layer may optionally further include other additives, such as thickeners (such as sodium carboxymethyl cellulose (CMC-Na)), etc.

[0099] In some embodiments, the negative electrode sheet can be prepared in the following manner: the components for preparing the negative electrode sheet described above, such as the negative electrode active material, the conductive agent, the binder, and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after processes such as drying and cold pressing, the negative electrode sheet can be obtained.

[0100] The electrolyte plays a role in conducting ions between the positive electrode sheet and the negative electrode sheet. The present application does not specifically limit the type of the electrolyte, and it can be selected according to requirements. For example, the electrolyte can be liquid, gel-like, or all-solid-state.

[0101] In some embodiments, the electrolyte solution may optionally further include additives. For example, the additives can include negative electrode film-forming additives, positive electrode film-forming additives, and can also include additives that can improve certain performances of the battery, such as additives for improving the overcharge performance of the battery, additives for improving the high-temperature or low-temperature performance of the battery, etc.

[0102] In some embodiments, the secondary battery further includes a separator. The present application does not particularly limit the type of the separator, and any well-known porous separator with good chemical stability and mechanical stability can be selected.

[0103] In some embodiments, the material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0104] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be made into an electrode assembly by a winding process or a stacking process.

[0105] In some embodiments, the secondary battery can include an outer package. The outer package can be used to encapsulate the above-mentioned electrode assembly and electrolyte.

[0106] In some embodiments, the outer package of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package of the secondary battery can also be a soft package, such as a pouch-type soft package. The material of the soft package can be plastic, and examples of the plastic can include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0107] The present application does not particularly limit the shape of the secondary battery, and it can be cylindrical, square, or any other shape. For example, Figure 1 is a secondary battery 5 with a square structure as an example.

[0108] In some embodiments, referring to Figure 2 , the outer package can include a housing 51 and a cover plate 53. Among them, the housing 51 can include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet, and the separator can form an electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. The number of the electrode assemblies 52 included in the secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.

[0109] In some embodiments, the secondary batteries can be assembled into a battery module, and the number of the secondary batteries included in the battery module can be one or more. The specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0110] Figure 3 is a battery module 4 as an example. Referring to Figure 3, in the battery module 4, multiple secondary batteries 5 can be arranged in sequence along the length direction of the battery module 4. Of course, they can also be arranged in any other way. Further, the multiple secondary batteries 5 can be fixed by fasteners.

[0111] Optionally, the battery module 4 can further include a housing having an accommodation space, and the multiple secondary batteries 5 are accommodated in the accommodation space.

[0112] In some embodiments, the above battery module can also be assembled into a battery pack. The number of battery modules included in the battery pack can be one or more, and those skilled in the art can select the specific number according to the application and capacity of the battery pack.

[0113] Figure 4 and Figure 5 is a battery pack 1 as an example. Refer to Figure 4 and Figure 5 , in the battery pack 1, a battery box and multiple battery modules 4 arranged in the battery box can be included. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can cover the lower box body 3 and form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in the battery box in any way.

[0114] In a fifth aspect, an embodiment of the present application provides an electrical device, including the battery of the fourth aspect of the present application.

[0115] In addition, the present application further provides an electrical device. The electrical device includes at least one of the secondary battery, battery module, or battery pack provided by the present application. The secondary battery, battery module, or battery pack can be used as the power source of the electrical device or as the energy storage unit of the electrical device. The electrical device can include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc., but not limited thereto.

[0116] As the electrical device, the secondary battery, battery module, or battery pack can be selected according to its usage requirements.

[0117] Figure 6 is an electrical device as an example. The electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements of the electrical device for the secondary battery, a battery pack or a battery module can be adopted.

[0118] The device as another example can be a mobile phone, a tablet computer, a laptop computer, etc. This device usually requires being thin and light, and a secondary battery can be used as the power source.

[0119] The technical solutions of the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0120] The parameters of the battery safety liquids in Examples 1 to 14 and Comparative Examples 1 to 2 of this application are according to the parameters in Table 1.

[0121]

[0122]

[0123] Example 33

[0124] A preparation method of a battery safety liquid includes the following steps:

[0125] Provide oxide particles with a coefficient of variation of particle size 0≤φ≤0.1;

[0126] Mix the oxide particles with a solution to obtain a battery safety liquid.

[0127] Example 34

[0128] A preparation method of a battery safety liquid includes the following steps:

[0129] Prepare oxide particles by the Stober method;

[0130] Mix the oxide particles with a solution to obtain a battery safety liquid.

[0131] Example 35

[0132] A preparation method of a battery safety liquid includes the following steps:

[0133] Prepare oxide particles by the Stober method;

[0134] Ultrasonically mix the oxide particles with a lithium salt solution to obtain a battery safety liquid.

[0135] Performance test

[0136] The batteries in Examples 15 to 32 and Comparative Examples 3 to 4 are subjected to 300 cycles of aging treatment, graphite negative electrode ternary positive electrode battery cores are made, the battery cores prepared in this test are soft-pack battery cores, and their conductivity is measured. Short-circuit impact performance test:

[0137] The battery preparation process is as follows:

[0138] The graphite anode is adopted, and the conductive agent is conductive carbon black; the binder is a 1:1 mixture of styrene-butadiene rubber and sodium carboxymethyl cellulose to obtain the anode slurry, which is coated on the copper electrode, rolled and dried, and sliced to obtain the anode sheet. The ratio of graphite material: conductive carbon black: binder = 96:2:2.

[0139] The lithium iron phosphate cathode is adopted, the conductive agent is conductive carbon black, and the binder is PVDF added with N-methylpyrrolidone, stirred, coated and dried; the cathode active material: conductive carbon black: binder = 96:2:2 to obtain the cathode slurry, which is coated on the aluminum foil, dried, rolled and sliced to obtain the cathode sheet.

[0140] The separator is a PE film.

[0141] The cathode sheet, anode sheet and separator are made into a soft-pack battery cell. Among them, the battery safety liquid is integrated in the soft-pack battery cells of Examples 15 to 33 and Comparative Example 4, and the battery safety liquid is released into the electrolyte after 300 cycles.

[0142] Viscosity test method: Use an Ubbelohde viscometer to measure the viscosity of the solution at room temperature of 25 °C.

[0143] Conductivity test method: Use a conductivity instrument to measure the conductivity of the solution at room temperature of 25 °C.

[0144] Short-circuit impact performance test method: A copper ball with a diameter of 6 cm falls from a height of 30 cm and contacts the geometric center of the front of the soft-pack battery cell.

[0145] Statistical experimental results are shown in Table 2.

[0146] As can be seen from Examples 15 to 32, the battery safety liquids composed of different oxide particles, solvents, and lithium salts can all achieve that when the battery safety liquid containing oxide particles is added to the electrolyte of the battery, the viscosity of the electrolyte can be increased, thereby reducing the risk of impact short circuit of the battery. At the same time, due to the increase in the viscosity of the electrolyte, the fluidity becomes smaller and the mass transfer resistance increases, and the conductivity of the battery cell decreases, thereby reducing the risk of thermal runaway of the battery cell. When the oxide particles include silicon dioxide, due to the inertness of silicon dioxide, the probability of reaction with the electrolyte can be further reduced. At the same time, the gaps between the silicon dioxide particles can accommodate the gas generated by the electrodes during long-term use of the battery. By increasing the viscosity of the electrolyte, the fluidity of the electrolyte is reduced and the flow of gas is reduced, thereby reducing the risk of further expansion of the battery.

[0147] The coefficient of variation of the particle size of the oxide particles is φ, where 0 ≤ φ ≤ 0.1, such that the oxide particles are particles with a relatively high uniformity of particle size distribution. As a result, when the battery safety liquid containing the oxide particles is added to the electrolyte of the battery, the viscosity of the electrolyte can be increased, thereby reducing the risk of impact short circuit of the battery. At the same time, due to the increase in the viscosity of the electrolyte, the fluidity becomes smaller, the mass transfer resistance increases, and the conductivity of the battery cell decreases, thus reducing the risk of thermal runaway of the battery cell.

[0148] When the particle size of the oxide particles is 0.001 μm ≤ R ≤ 100 μm, within this range, the viscosity of the electrolyte can be increased, the fluidity of the electrolyte can be reduced, and the flow of gas can be reduced, thereby reducing the risk of battery swelling.

[0149] When the mass ratio of the oxide particles in the battery safety liquid is 20% ≤ A1 ≤ 90%, within this range, the mass ratio of the oxide particles can be increased, so that while increasing the viscosity of the electrolyte, the probability of reaction between the oxide particles and the electrolyte can be reduced, and the risk of impact short circuit and thermal runaway of the battery can be reduced.

[0150] It can be seen from Comparative Examples 1 and 2 that neither adding no oxide particles nor adding oxide particles with a coefficient of variation greater than 0.1 can reduce the risk of impact short circuit of the battery.

[0151] The above are only the preferred embodiments of the present application, and do not limit the patent scope of the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the patent protection scope of the present application.

Claims

1. A battery safety liquid, characterized in that, it comprises a solution and oxide particles, wherein the coefficient of variation of the particle size of the oxide particles is φ, 0 ≤ φ ≤ 0.1, and the coefficient of variation of the particle size φ = the average variance of the particle size of the particles / the average value of the particle size of the particles.

2. The battery safety liquid according to claim 1, characterized in that, 0 ≤ φ ≤ 0.

05.

3. The battery safety liquid according to claim 1 or 2, characterized in that, the oxide particles comprise at least one of titanium dioxide, aluminum oxide, manganese dioxide, nickel oxide, cobalt oxide, iron oxide, zinc oxide and silicon dioxide.

4. The battery safety liquid according to any one of claims 1 to 3, characterized in that, the particle size of the oxide particles is R, wherein: 0.001 μm ≤ R ≤ 100 μm; optionally, 0.1 μm ≤ R ≤ 1 μm.

5. The battery safety liquid according to any one of claims 1 to 4, characterized in that, the mass proportion of the oxide particles in the battery safety liquid is A1, wherein: 20% ≤ A1 ≤ 90%; optionally, 40% ≤ A1 ≤ 80%.

6. The battery safety liquid according to any one of claims 1 to 5, characterized in that, the solution comprises a lithium salt solution, wherein: the solute of the lithium salt solution comprises at least one of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate; and / or, the solvent of the lithium salt solution comprises at least one of ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate.

7. A preparation method of the battery safety liquid according to any one of claims 1 to 6, characterized in that, it comprises the following steps: providing oxide particles with a coefficient of variation of particle size 0 ≤ φ ≤ 0.1; mixing the oxide particles with the solution to obtain the battery safety liquid.

8. The preparation method of the battery safety liquid according to claim 7, characterized in that, step of providing oxide particles with a coefficient of variation of particle size 0 ≤ φ ≤ 0.1 comprises: preparing the oxide particles by the Stober method.

9. The preparation method of the battery safety liquid according to claim 7 or 8, characterized in that, step of mixing the oxide particles with the lithium salt solution to obtain the battery safety liquid comprises: ultrasonically mixing the oxide particles with the lithium salt solution to obtain the battery safety liquid.

10. A lithium-ion battery, characterized in that it comprises an electrolyte and a battery safety liquid, wherein the battery safety liquid is the battery safety liquid according to any one of claims 1 to 6 or the battery safety liquid prepared by the preparation method of the battery safety liquid according to any one of claims 7 to 9.

11. The lithium-ion battery according to claim 10, characterized in that, the mass fraction of the electrolyte is w1, the mass fraction of the battery safety liquid is w2, and the mass fraction of the oxide particles in the battery safety liquid is w3, wherein: 5% ≤ w3 / (w1 + w2) ≤ 35%; optionally, 10% ≤ w3 / (w1 + w2) ≤ 30%.

12. The lithium-ion battery according to claim 10 or 11, characterized in that, the viscosity of the electrolyte is V1, and the viscosity of the mixture of the battery safety liquid and the electrolyte is V2, wherein: 2 ≤ V2:V1 ≤ 10; optionally, 5 ≤ V2:V1 ≤ 10.

13. The lithium ion battery according to any one of claims 10 to 12, characterized in that the electrolyte includes a lithium salt electrolyte.

14. The lithium ion battery according to claim 13, characterized in that the lithium salt electrolyte includes a lithium salt and a solvent, wherein: the lithium salt includes at least one of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, and lithium hexafluoroarsenate; and / or, the solvent includes at least one of ethylene carbonate, diethyl carbonate, dimethyl carbonate, and ethyl methyl carbonate.

15. An electrical device, characterized in that it includes the lithium ion battery according to any one of claims 10 to 14.

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