Lithium ion battery oxygen release agent, lithium ion battery and electric device

Abstract

The application provides a lithium ion battery oxygen releasing agent, a lithium ion battery and an electric device. The lithium ion battery oxygen releasing agent comprises an inorganic oxygen releasing chemical reagent core and an organic polymer coating layer coated on the surface of the inorganic oxygen releasing chemical reagent core, and the thermal decomposition temperature of the organic polymer in the coating layer is 150 DEG C-220 DEG C. The lithium ion battery oxygen releasing agent is added to the lithium ion battery. When the internal temperature of the battery rises to the decomposition temperature of the organic polymer, the coating layer of the lithium ion battery oxygen releasing agent decomposes, the inorganic oxygen releasing chemical reagent of the core starts to decompose and release oxygen, the oxygen content in the battery is increased, the incomplete oxidation of the organic solvent in the electrolyte to form the combustible gas CO is inhibited, the complete oxidation of the organic solvent to form the fire extinguishing agent CO2 is promoted, the combustion or explosion of the battery is inhibited, the energy released by the thermal runaway of the battery is reduced, and the overall safety of the energy storage system is improved.

Description

TECHNICAL FIELD

[0001] The embodiment of the present application relates to the technical field of lithium ion batteries, in particular to a lithium ion battery oxygen releasing agent, a lithium ion battery and an electric equipment. BACKGROUND

[0002] The lithium ion battery is one of the most widely used batteries at present due to its excellent electrochemical performance and mature production process technology. Unlike small portable electronic devices such as mobile phones and notebook computers, the lithium ion battery for electric vehicles and energy storage has a larger capacity and a more complex use environment, and has a higher requirement for safety performance. Generally speaking, the larger the capacity of the battery, the higher the internal temperature during operation. Under the conditions of high temperature or large rate charging and discharging, the heat release of the high-energy electrode and the temperature rise of the combustible organic solvent in the electrolyte will cause a series of side reactions to occur, eventually leading to thermal runaway.

[0003] Thermal runaway is a chain reaction phenomenon caused by various incentives. There are many reasons for the thermal runaway of the lithium ion battery, mainly the internal short circuit of the battery, such as dendritic lithium precipitation, dendritic puncture of the separator, short circuit caused by overheating, overcharging, mechanical impact, etc., which further causes the electrolyte to burn and spread to the battery cell, causing serious thermal runaway, causing the battery to self-ignite, and even causing explosion in severe cases. In order to improve the safety of the lithium ion battery, it is necessary to control the thermal runaway of the battery, reduce the heat generated by the thermal runaway, and reduce the destructive power caused by the thermal runaway of the battery. SUMMARY

[0004] In view of this, the present application provides a lithium ion battery oxygen releasing agent, which comprises an inorganic oxygen releasing chemical agent core and an organic polymer coating layer coated on the surface of the inorganic oxygen releasing chemical agent core, and the thermal decomposition temperature of the organic polymer in the coating layer is 150-220 DEG C. The lithium ion battery oxygen releasing agent is added to the lithium ion battery. When the internal temperature of the battery rises to the decomposition temperature of the organic polymer, the coating layer of the lithium ion battery oxygen releasing agent decomposes, the inorganic oxygen releasing chemical agent of the core starts to react and releases oxygen, increases the oxygen content in the battery, and then inhibits the incomplete oxidation of the organic solvent in the electrolyte to generate combustible gas CO, reduces the generation of combustible gas, and promotes the complete oxidation of the organic solvent to generate fire extinguishing agent CO2, inhibits the combustion or explosion of the battery, reduces the energy released by the thermal runaway of the battery, and improves the overall safety of the energy storage system.

[0005] The first aspect of the present application provides a lithium ion battery oxygen releasing agent, which comprises a core and a coating layer coated on the surface of the core, the core comprises an inorganic oxygen releasing chemical agent, and the coating layer comprises an organic polymer, and the thermal decomposition temperature of the organic polymer is 150-220 DEG C.

[0006] In some embodiments of the present application, the inorganic oxygen releasing chemical agent comprises calcium peroxide and / or magnesium peroxide.

[0007] In some embodiments of the present application, the organic polymer has a compressive strength of 80 MPa-150 MPa.

[0008] In some embodiments of the present application, the organic polymer comprises one or more of a vinylidene fluoride-hexafluoropropylene copolymer, a polyurea-formaldehyde resin, and a polymethyl methacrylate.

[0009] In some embodiments of the present application, the core has a diameter of 100 nm-1 μm, and the coating layer has a thickness of 20 nm-200 nm.

[0010] In some embodiments of the present application, the lithium ion battery oxygen releasing agent has a mass ratio of the inorganic oxygen releasing chemical agent to the organic polymer of 8-20:1.

[0011] The second aspect of the present application provides a method for preparing the lithium ion battery oxygen releasing agent of the first aspect of the present application, comprising:

[0012] The inorganic oxygen releasing chemical agent is added to the organic polymer solution, and the lithium ion battery oxygen releasing agent is obtained after drying.

[0013] The third aspect of the present application provides a lithium ion battery comprising the lithium ion battery oxygen releasing agent of the first aspect of the present application.

[0014] In some embodiments of the present application, the lithium ion battery comprises a positive electrode sheet, a negative electrode sheet, and a separator and an electrolyte between the positive electrode sheet and the negative electrode sheet, and the positive electrode sheet, and / or the negative electrode sheet, and / or the separator, and / or the electrolyte contains the lithium ion battery oxygen releasing agent.

[0015] In some embodiments of the present application, the positive electrode sheet comprises a positive electrode current collector and a positive electrode active layer loaded on the positive electrode current collector, and the positive electrode active layer comprises the lithium ion battery oxygen releasing agent.

[0016] Alternatively, the positive electrode sheet comprises a positive electrode current collector, a positive electrode active layer loaded on the positive electrode current collector, and an oxygen releasing material layer arranged on a surface of the positive electrode active layer away from the positive electrode current collector, and the oxygen releasing material layer comprises the lithium ion battery oxygen releasing agent.

[0017] In some embodiments of the present application, the negative electrode sheet comprises a negative electrode current collector and a negative electrode active layer loaded on the negative electrode current collector, and the negative electrode active layer comprises the lithium ion battery oxygen releasing agent.

[0018] Alternatively, the negative electrode sheet comprises a negative electrode current collector, a negative electrode active layer loaded on the negative electrode current collector, and an oxygen releasing material layer arranged on a side surface of the negative electrode active layer away from the negative electrode current collector, the oxygen releasing material layer comprising the lithium ion battery oxygen releasing agent.

[0019] In some embodiments of the present application, the mass of the lithium ion battery oxygen releasing agent accounts for 3%-10% of the total mass of the positive electrode sheet and the negative electrode sheet.

[0020] In some embodiments of the present application, the separator comprises a polymer separator substrate and an oxygen releasing material layer arranged on the polymer separator substrate, the oxygen releasing material layer comprising the lithium ion battery oxygen releasing agent, the thickness of the oxygen releasing material layer being 1 μm-3 μm, and the mass percentage of the lithium ion battery oxygen releasing agent in the separator being 10%-30%.

[0021] In some embodiments of the present application, the mass percentage of the lithium ion battery oxygen releasing agent in the electrolyte is 2%-8%.

[0022] The fourth aspect of the present application provides a power consumption device comprising the lithium ion battery of the third aspect. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 A cross-sectional structure schematic diagram of the lithium ion battery oxygen releasing agent provided by an embodiment of the present application;

[0024] Figure 2 A structure schematic diagram of the lithium ion battery provided by an embodiment of the present application;

[0025] Figure 3 A structure schematic diagram of the lithium ion battery provided by another embodiment of the present application;

[0026] Figure 4 A structure schematic diagram of the lithium ion battery provided by yet another embodiment of the present application.

[0027] BRIEF DESCRIPTION OF DRAWINGS

[0028] 100 - lithium ion battery oxygen releasing agent; 101 - coating layer; 102 - inner core; 200 - lithium ion battery; 201 - positive electrode sheet; 2011 - positive electrode current collector; 2012 - positive electrode active layer; 202 - negative electrode sheet; 2021 - negative electrode current collector; 2022 - negative electrode active layer; 203 - separator; 2031 - separator substrate; 204 - electrolyte; 205 - battery shell; 206 - oxygen releasing material layer. DETAILED DESCRIPTION

[0029] The present application will be further described in detail below in combination with preferred embodiments, but the protection scope of the present application is not limited to the following specific embodiments.

[0030] In the present application, all the professional terms have the same meaning as generally understood by those skilled in the art, and the professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present application.

[0031] Thermal runaway is a chain reaction phenomenon triggered by various incentives. There are many reasons for lithium-ion battery thermal runaway, mainly the short circuit of the battery, such as dendritic lithium precipitation, dendritic puncture of the separator, overheating, overcharging, mechanical impact, etc., which leads to short circuit, and then causes electrolyte combustion, and then spreads to the battery cell, causing serious thermal runaway, causing the battery to self-ignite, and in severe cases even causing explosion. Battery thermal runaway has three characteristic temperatures, namely the battery self-heating temperature T0, the battery thermal runaway initiation temperature T1, and the battery thermal runaway maximum temperature T2. The battery self-heating temperature T0 is usually the temperature at which the solid electrolyte interface (SEI) film of the lithium-ion battery begins to decompose. After the decomposition of the SEI film, the negative electrode of the battery loses protection and reacts with the electrolyte, generating heat and causing the internal temperature of the battery to rise, gradually causing the internal separator to melt, causing internal short circuit of the battery, and then releasing a large amount of heat. The heat generated by these reactions will cause the internal temperature of the battery to rise, and the temperature rise will further accelerate the progress of these reactions, forming a positive feedback process of heat, and eventually triggering battery runaway at a certain critical point, i.e. the battery thermal runaway initiation temperature T1. After the thermal runaway begins, a large amount of gas and heat is generated by the violent reaction, and the heat further heats the gas. The expanding gas bursts through the battery cell shell, causing phenomena such as material ejection and explosion, and the thermal runaway reaches the maximum temperature, i.e. the battery thermal runaway maximum temperature T2.

[0032] Generally, once the thermal runaway reaction occurs, it can only be terminated when the reactants are completely burned out. Conventional fire extinguishing methods cannot truly reach the substances undergoing reaction. The battery self-heating temperature T0 of the lithium iron phosphate battery is slightly higher than that of the lithium cobalt oxide battery and the ternary battery, but the energy released by the thermal runaway of the lithium iron phosphate battery is twice or even more than that of the lithium cobalt oxide battery and the ternary battery, and the destructive power is greater. Therefore, reducing the energy released by the thermal runaway of the lithium iron phosphate battery is of great significance to improve the safety of the battery. At present, to improve the safety of lithium-ion batteries, the main method in the industry is to coat or dope the electrode material to improve the thermal stability of the battery material, or to modify the multifunctional composite separator, use fluorine-containing solvents and flame-retardant additives in the electrolyte to improve the stability of the separator and the electrolyte, but these methods still have limitations in improving safety.

[0033] To solve the above problems, the lithium ion battery oxygen releasing agent, the lithium ion battery and the electric equipment provided by the present application are provided. The lithium ion battery oxygen releasing agent comprises an inorganic oxygen releasing chemical reagent core and an organic polymer coating layer coated on the surface of the inorganic oxygen releasing chemical reagent core, and the decomposition temperature of the organic polymer in the coating layer is greater than or equal to 150 DEG C. The lithium ion battery oxygen releasing agent is added to the lithium ion battery. When the internal temperature of the battery rises to the decomposition temperature of the organic polymer, the coating layer of the lithium ion battery oxygen releasing agent decomposes, the inorganic oxygen releasing chemical reagent of the core starts to react and releases oxygen, the oxygen content in the battery is increased, the incomplete oxidation of the organic solvent in the electrolyte to generate combustible gas CO is inhibited, the complete oxidation of the organic solvent to generate fire extinguishing agent CO2 is promoted, the combustion or explosion of the battery is inhibited, the energy released by the thermal runaway of the battery is reduced, and the overall safety of the energy storage system is improved.

[0034] Reference Figure 1 , Figure 1 The cross-sectional structure schematic diagram of the lithium ion battery oxygen releasing agent provided by an embodiment of the present application is provided. The lithium ion battery oxygen releasing agent 100 comprises a core 102 and a coating layer 101 coated on the surface of the core 102. The core 102 comprises an inorganic oxygen releasing chemical reagent, and the coating layer 101 comprises an organic polymer, and the decomposition temperature of the organic polymer is 150 DEG C-220 DEG C. In the present application, the inorganic oxygen releasing chemical reagent is coated by using the organic polymer with a suitable decomposition temperature, and the lithium ion battery oxygen releasing agent with core-shell structure is obtained. When the battery thermal runaway temperature reaches 160 DEG C or above, the organic polymer coating layer 101 is decomposed and broken, the core 102 is exposed, the inorganic oxygen releasing chemical reagent in the core 102 is decomposed to generate O2 under high temperature conditions, the oxygen content in the battery is increased, the organic solvent such as ethylene carbonate (EC), diethyl carbonate (DEC) and dimethyl carbonate (DMC) in the electrolyte is completely oxidized to generate fire extinguishing agent CO2, the phenomenon that the incomplete oxidation of the organic solvent generates combustible gas CO and then breaks the safety valve to release more energy is effectively avoided, the further development of thermal runaway is controlled, and the safety risk is reduced. The chemical formula of the incomplete oxidation of part of the components in the lithium ion battery electrolyte under the condition of insufficient oxygen content is as follows:

[0035] O2+C3H4O3(EC)→3CO+2H2O;

[0036] 3.5O2+C5H 10 O3(DEC)→5CO+5H2O;

[0037] 1.5O2+C3H6O3(DMC)→3CO+3H2O.

[0038] By releasing oxygen in the battery through the lithium ion battery oxygen releasing agent, the chemical formula of the complete oxidation of these components in the electrolyte under the condition of sufficient oxygen is as follows:

[0039] 2.5O2+C3H4O3(EC)→3CO2+2H2O;

[0040] 6O2+C5H 10 O3(DEC)→5CO2+5H2O;

[0041] 3O2+C3H6O3(DMC)→3CO2+3H2O.

[0042] In the embodiments of the present application, the core 102 comprises inorganic oxygen-releasing chemical reagents, and the inorganic oxygen-releasing chemical reagents comprise calcium peroxide and / or magnesium peroxide. In the present application, suitable inorganic peroxides are selected as the inorganic oxygen-releasing chemical reagents, and these peroxides can be decomposed by heat after the decomposition of the coating layer 101, and a large amount of oxygen is generated by the reaction. Among them, the chemical formula of the decomposition of part of the peroxides at high temperature is: 2CaO2→2CaO+O2; 2MgO2→2MgO+O2. The oxygen released by these inorganic oxygen-releasing chemical reagents can greatly improve the oxygen concentration in the electrolyte of the lithium ion battery, and then make the carbonic acid ester organic solvent in it completely oxidized under the condition of high oxygen concentration. On the one hand, it avoids the incomplete oxidation of these carbonic acid ester organic solvents under the condition of insufficient oxygen to generate flammable gas CO, effectively inhibits the subsequent combustion of more heat, further aggravates the "thermal runaway" of the battery, avoids the occurrence of explosion and other dangers; on the other hand, the complete oxidation of these carbonic acid ester organic solvents under the condition of sufficient oxygen generates fire extinguishing agent CO2, and the CO2 gas can exclude air and surround the surface of the burning electrolyte, reduce the oxygen concentration around the combustible electrolyte in the cell, and produce a suffocating effect to effectively extinguish the fire.

[0043] In the embodiments of the present application, the coating layer 101 comprises an organic polymer, and the thermal decomposition temperature of the organic polymer is 150-220°C. In some specific embodiments of the present application, the thermal decomposition temperature of the organic polymer may, for example, be 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, 205°C, 210°C, 215°C, or 220°C. In the embodiments of the present application, the organic polymer is an organic polymer that does not react with the electrolyte, so as to ensure that it can stably exist in the lithium ion battery and does not affect the normal operation of the lithium ion battery. In some embodiments of the present application, the organic polymer comprises one or more of a vinylidene fluoride-hexafluoropropylene copolymer, a polyurea-formaldehyde resin, and a polymethyl methacrylate. Among them, the thermal decomposition temperature of the vinylidene fluoride-hexafluoropropylene copolymer is 150-170°C, the thermal decomposition temperature of the polyurea-formaldehyde resin is 200-220°C, and the thermal decomposition temperature of the polymethyl methacrylate is 150-180°C. By selecting the organic polymer with a thermal decomposition temperature in the above suitable range as the coating layer 101 of the lithium ion battery oxygen releasing agent 100, it can be ensured that the lithium ion battery oxygen releasing agent exists in the lithium ion battery in the form of a core-shell structure when the battery is normally operated, avoiding exposure of the inorganic oxygen releasing chemical reagent in the core 102, generating oxygen and thus causing the battery to bulge and affecting the electrochemical performance of the battery. However, these organic polymers begin to decompose when the temperature of the battery reaches about 200°C, the coating layer 101 of the lithium ion battery oxygen releasing agent 100 gradually cracks, and the core 102 wrapped by the coating layer 101 is exposed. At this time, the temperature inside the lithium ion battery has reached about the battery thermal runaway initiation temperature T1, and the battery is about to undergo a severe thermal runaway reaction, generating a large amount of heat and gas. However, the exposure of the core 102 of the present application causes the inorganic oxygen releasing chemical reagent therein to decompose to generate a large amount of O2 in this environment, greatly increasing the oxygen content in the battery, causing the complete oxidation of the organic solvent in the electrolyte to generate the fire extinguishing agent CO2, greatly hindering the further thermal runaway of the battery, effectively reducing the heat generated by the battery thermal runaway, and avoiding the safety hazards such as explosion caused by severe thermal runaway.

[0044] The thermal decomposition temperature is the temperature at which the molecular chain of the organic polymer begins to decompose under heat, and is one of the important thermal properties of the polymer. The thermal decomposition temperature of the organic polymer can be obtained by thermal gravimetric analysis. The thermal decomposition temperature can be tested by thermal gravimetric analysis (TG) and differential scanning calorimetry (DSC) in combination. The test conditions are as follows: under the protection of argon atmosphere, the temperature is raised from 25°C to 500°C at a rate of 5°C / min.

[0045] In some embodiments of the present application, the compressive strength of the organic polymer is, for example, 80 MPa, 90 MPa, 100 MPa, 110 MPa, 120 MPa, 130 MPa, 140 MPa, or 150 MPa. The compressive strength can be measured according to GB / T 1448-2005. By selecting an organic polymer with a compressive strength in a suitable range as the cladding layer material of the lithium ion battery oxygen releasing agent, the stability of the structure of the lithium ion battery oxygen releasing agent during the preparation of the battery can be ensured when the lithium ion battery oxygen releasing agent is added at different positions of the battery.

[0046] In some embodiments of the present application, the diameter of the core 102 is, for example, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, or 1 μm; and the thickness of the cladding layer 101 is, for example, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 80 nm, 100 nm, 120 nm, 140 nm, 150 nm, 160 nm, 180 nm, or 200 nm. By controlling the diameter of the core and the thickness of the cladding layer of the lithium ion battery oxygen releasing agent within a suitable range, on the one hand, the cladding layer 101 can effectively cladding and isolate heat from the core 102 before the battery experiences thermal runaway, effectively preventing the core 102 from thermal decomposition to generate oxygen before reaching the thermal runaway state, thereby affecting the performance of the battery; on the other hand, the cladding layer 101 can also completely decompose when the battery reaches a certain temperature, so that the core 102 is completely exposed, effectively exerting its oxygen releasing and fire extinguishing effect.

[0047] In some embodiments of the present application, the mass ratio of the inorganic oxygen releasing chemical reagent to the organic polymer in the lithium ion battery oxygen releasing agent 100 is 8-20:1. In some embodiments of the present application, the mass ratio of the inorganic oxygen releasing chemical reagent to the organic polymer in the lithium ion battery oxygen releasing agent 100 is 8:1, 9:1, 10:1, 118:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, or 20:1. By reasonably controlling the mass ratio of the inorganic oxygen releasing chemical reagent and the organic polymer in the lithium ion battery oxygen releasing agent, the comprehensive performance of the organic polymer cladding effect and the oxygen releasing and fire extinguishing effect of the inorganic oxygen releasing chemical reagent of the lithium ion battery oxygen releasing agent can be better.

[0048] The application coats inorganic oxygen-releasing chemical reagents by using organic polymers with a thermal decomposition temperature in a suitable range, and applies the obtained lithium ion battery oxygen-releasing agent in lithium ion batteries. When the internal temperature of the battery rises to the decomposition temperature of the organic polymer, the coating layer of the lithium ion battery oxygen-releasing agent decomposes, and the inorganic oxygen-releasing chemical reagents in the core begin to decompose and release oxygen when heated, thereby increasing the oxygen content in the battery, inhibiting the incomplete oxidation of organic solvents in the electrolyte to generate flammable gas CO, promoting the complete oxidation of organic solvents to generate fire extinguishing agent CO2, inhibiting the combustion or explosion of the battery, reducing the energy released by the thermal runaway of the battery, and improving the overall safety of the energy storage system.

[0049] The application also provides a preparation method of the lithium ion battery oxygen-releasing agent provided in the foregoing.

[0050] S101, adding inorganic oxygen-releasing chemical reagents to a solution of organic polymers, stirring and mixing, and ultrasonic dispersion to obtain a lithium ion battery oxygen-releasing agent precursor mixed solution;

[0051] S102, drying and grinding the lithium ion battery oxygen-releasing agent precursor mixed solution to obtain a lithium ion battery oxygen-releasing agent.

[0052] In step S101, the stirring and mixing speed is 500 rpm-1000 rpm. In some embodiments of the application, the stirring and mixing speed may, for example, be 500 rpm, 550 rpm, 600 rpm, 650 rpm, 700 rpm, 750 rpm, 800 rpm, 850 rpm, 900 rpm, 950 rpm, or 1000 rpm. In the embodiments of the application, the ultrasonic dispersion time is 5h-10h. In some embodiments of the application, the ultrasonic dispersion time may, for example, be 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h, or 10h.

[0053] In step S102, the drying method includes but is not limited to spray drying, and the spray drying temperature is 40℃-60℃. In some embodiments of the application, the spray drying temperature may, for example, be 40℃, 45℃, 50℃, 55℃, or 60℃.

[0054] The application also provides a lithium ion battery comprising the lithium ion battery oxygen-releasing agent provided in the foregoing. Figure 2As shown, the lithium ion battery 200 includes a battery case 205, and a positive electrode sheet 201, a negative electrode sheet 202, a separator 203 and an electrolyte 204 accommodated inside the battery case 205, wherein the positive electrode sheet 201 and the negative electrode sheet 202 are separated by the separator 203. In the embodiments of the present application, the distribution position of the lithium ion battery oxygen releasing agent in the lithium ion battery is not limited, including but not limited to the positive electrode sheet, the negative electrode sheet, the separator and the electrolyte.

[0055] In some embodiments of the present application, the lithium ion battery oxygen releasing agent is distributed in the positive electrode sheet 201. As shown in the drawings, Figure 2 In some embodiments of the present application, the lithium ion battery oxygen releasing agent is distributed in the positive electrode sheet 201. As shown in the drawings, Figure 3 In some embodiments of the present application, the lithium ion battery oxygen releasing agent is distributed in the positive electrode sheet 201. As shown in the drawings,

[0056] In some embodiments of the present application, the lithium ion battery oxygen releasing agent is distributed in the negative electrode sheet 202. As shown in the drawings, Figure 2 In some embodiments of the present application, the lithium ion battery oxygen releasing agent is distributed in the positive electrode sheet 201. As shown in the drawings, Figure 3 In some embodiments of the present application, the lithium ion battery oxygen releasing agent is distributed in the positive electrode sheet 201. As shown in the drawings,

[0057] In some embodiments of the present application, the thickness of the oxygen release material layer 206 is 1-4 μm when the oxygen release material layer 206 is arranged on the positive electrode sheet 201 and / or the negative electrode sheet 202. In some embodiments of the present application, the thickness of the oxygen release material layer may, for example, be 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, or 4 μm. The oxygen release material layer may, for example, be arranged only on the positive active layer 2012, only on the negative active layer 2022, or on both the positive active layer 2012 and the negative active layer 2022.

[0058] In some embodiments of the present application, the mass of the lithium ion battery oxygen release agent accounts for 3-10% of the total mass of the positive electrode sheet 201 and the negative electrode sheet 202. In some embodiments of the present application, the mass of the lithium ion battery oxygen release agent may, for example, account for 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, or 10% of the total mass of the positive electrode sheet 201 and the negative electrode sheet 202. The lithium ion battery oxygen release agent may, for example, be arranged only in the positive active layer 2012, only in the negative active layer 2022, or in both the positive active layer 2012 and the negative active layer 2022. When the lithium ion battery oxygen release agent is arranged in both the positive active layer 2012 and the negative active layer 2022, the mass percentage of the lithium ion battery oxygen release agent in the positive active layer 2012 and the mass percentage of the lithium ion battery oxygen release agent in the negative active layer 2022 may be the same or different. By controlling the amount of lithium ion battery oxygen release agent in the positive / negative electrode sheet within an appropriate range, on the one hand, the oxygen release agent does not excessively occupy the proportion of the positive / negative electrode material in the electrode sheet, affecting the specific capacity or other electrochemical properties of the battery; on the other hand, the oxygen release agent can better play its oxygen release and fire extinguishing effect, effectively reducing the energy released by the thermal runaway of the lithium ion battery.

[0059] In some embodiments of the present application, the lithium ion battery oxygen release agent is arranged in the separator 203. For example, the lithium ion battery oxygen release agent may, for example, be arranged in the pores of the separator 203. Figure 4As shown, in some embodiments of the present application, the separator 203 comprises a separator base 2031 and an oxygen releasing material layer 206 disposed on the separator base 2031. In embodiments of the present application, the oxygen releasing material layer 206 can be disposed on one side surface or both side surfaces of the separator base 2031. In embodiments of the present application, when the oxygen releasing material layer 206 is disposed on the separator 203, the thickness of the oxygen releasing material layer 206 is 1 μm-3 μm. In some embodiments of the present application, the thickness of the oxygen releasing material layer can be, for example, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm. When the oxygen releasing material layer 206 is distributed on both side surfaces of the separator base 2031, the thickness of the oxygen releasing material layer 206 on both side surfaces of the separator base 2031 can be the same or different. In embodiments of the present application, the mass percentage content of the lithium ion battery oxygen releasing agent in the separator 203 is 10%-30%. In some embodiments of the present application, the mass percentage content of the lithium ion battery oxygen releasing agent in the separator 203 can be, for example, 10%, 12%, 14%, 15%, 16%, 18%, 20%, 22%, 24%, 25%, 26%, 28%, 30%. By controlling the thickness of the oxygen releasing material layer in the separator and the content of the lithium ion battery oxygen releasing agent, the present application can better exert the oxygen releasing and fire extinguishing effect of the lithium ion battery oxygen releasing agent and effectively reduce the energy released by the thermal runaway of the lithium ion battery while ensuring that it does not affect the ion transmission effect of the separator.

[0060] In some embodiments of the present application, the lithium ion battery oxygen releasing agent is distributed in the electrolyte 204. In embodiments of the present application, when the lithium ion battery oxygen releasing agent is distributed in the electrolyte 204, the mass percentage content of the lithium ion battery oxygen releasing agent in the electrolyte 204 is 2%-8%. In some embodiments of the present application, the mass percentage content of the lithium ion battery oxygen releasing agent in the electrolyte 204 can be, for example, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%. By controlling the amount of the lithium ion battery oxygen releasing agent added in the electrolyte of the lithium ion battery within a suitable range, on the one hand, the present application can ensure that too much oxygen releasing agent does not affect the electrochemical performance of the electrolyte; on the other hand, the present application can better exert the oxygen releasing and fire extinguishing effect of the lithium ion battery oxygen releasing agent and effectively reduce the energy released by the thermal runaway of the lithium ion battery.

[0061] In the embodiments of the present application, the lithium ion battery 200 includes but is not limited to a winding type lithium ion battery, a laminated lithium ion battery. In the embodiments of the present application, the positive active material of the positive active layer 2012 in the positive electrode includes a lithium iron phosphate material. In the embodiments of the present application, the negative active material in the negative active layer 2022 can be any negative active material for lithium ion batteries known in the art, including but not limited to one or more of a carbon-based negative active material, a silicon-based negative active material, a tin-based negative active material, a lithium metal negative active material. Among them, the carbon-based negative electrode can include natural graphite, artificial graphite, hard carbon, soft carbon, graphene, etc.; the silicon-based negative electrode can include silicon, silicon-carbon, silicon-oxygen, pre-lithium silicon-oxygen, pre-lithium silicon-carbon, etc.; the tin-based negative electrode can include tin, tin-carbon, tin-oxygen, tin metal compounds, but is not limited thereto. The battery shell 205 includes but is not limited to a steel shell, an aluminum shell, a nickel-plated iron shell, or an aluminum plastic film and the like.

[0062] The lithium ion battery provided by the present application adds a lithium ion battery oxygen releasing agent with a core-shell structure of an inorganic oxygen releasing chemical reagent coated by an organic polymer in the lithium ion battery, the adding position includes but is not limited to the positive electrode sheet, the negative electrode sheet, the separator and the electrolyte, the lithium ion battery oxygen releasing agent stably exists in the lithium ion battery at normal temperature, does not affect the electrochemical performance of the battery, can effectively release oxygen and extinguish the fire when the battery occurs thermal runaway, thereby reducing the heat brought by the thermal runaway and improving the safety of the battery.

[0063] The present application also provides a power consuming device, which comprises the lithium ion battery provided in the foregoing. The power consuming device can be, for example, an electric vehicle, a mobile phone, a tablet computer, a notebook computer, a wearable device (watch, bracelet), a digital camera, etc.

[0064] The present application will be further described in the following embodiments:

[0065] Embodiment 1

[0066] A composite material with a core-shell structure of a polyurea-formaldehyde resin coating layer and a magnesium peroxide core is used as a lithium ion battery oxygen releasing agent polyurea-formaldehyde resin@MgO2, the thermal decomposition temperature of the polyurea-formaldehyde resin is 200℃, the thickness of the coating layer is 50nm, and the diameter of the core is 600nm;

[0067] The positive active material lithium iron phosphate, the conductive agent Super P, the binder polyvinylidene fluoride (PVDF) and the lithium ion battery oxygen releasing agent (polyurea-formaldehyde resin@MgO2) are mixed in a mass ratio of 92:3:2:3, N-methyl pyrrolidone is used as a solvent, stirring is carried out at a speed of 1000rpm-5000rpm for about 6 hours under the condition of 25℃±3℃, and a uniform and stable positive active slurry is obtained. The single-sided area density is 1.55g / dm 3The positive electrode sheet containing the oxygen release agent for lithium-ion batteries is coated on both sides of the positive electrode current collector, baked, rolled, and cut. A 20μm-thick PP separator is used as the separator, and graphite is used as the negative electrode active material. After lamination, shell insertion, tab welding, and 80°C vacuum baking of the dry cell, approximately 250g of carbonate electrolyte is injected. The electrolyte solvent is ethyl methyl carbonate (EMC), diethyl carbonate (DMC), and ethylene carbonate (EC) in a 1:1:1 volume ratio, and the solute is 1 mol / L LiPF6. The cell is then immersed at 45°C for 48 hours, pre-charged and formed, aged at 45°C for 48 hours, vented under negative pressure, and the liquid injection port sealed. The target cell is then cycled three times at a 0.5C rate and fully charged. The battery was tested in an Accelerating Rate Calorimeter (ARC) under conditions of elevated temperature to detect thermal runaway of the battery and the energy released. The results are shown in Table 1.

[0068] Example 2

[0069] A core-shell composite material with a coating layer of polyurea-formaldehyde resin and a core of magnesium peroxide is used as an oxygen release agent for lithium-ion batteries. The thermal decomposition temperature of the polyurea-formaldehyde resin is 200°C, the thickness of the coating layer is 50nm, and the diameter of the core is 600nm.

[0070] The positive electrode active material lithium iron phosphate, conductive agent Super P, binder polyvinylidene fluoride (PVDF), lithium ion battery oxygen release agent (polyurea-formaldehyde resin @MgO2) are mixed in a mass ratio of 89:3:2:6, with N-methylpyrrolidone as solvent, and stirred at a speed of 1000rpm-5000rpm for about 6 hours at 25℃±3℃ to obtain a uniform and stable positive electrode active slurry with a single surface density of 1.60g / dm 3The positive electrode sheet containing the oxygen release agent for lithium-ion batteries is coated on both sides of the positive electrode current collector, baked, rolled, and cut. A 20μm-thick PP separator is used as the separator, and graphite is used as the negative electrode active material. After lamination, shell insertion, tab welding, and 80°C vacuum baking of the dry cell, approximately 250g of carbonate electrolyte is injected. The electrolyte solvent is ethyl methyl carbonate (EMC), diethyl carbonate (DMC), and ethylene carbonate (EC) in a 1:1:1 volume ratio, and the solute is 1 mol / L LiPF6. The cell is then immersed at 45°C for 48 hours, pre-charged and formed, aged at 45°C for 48 hours, vented under negative pressure, and the liquid injection port sealed. The target cell is then cycled three times at a 0.5C rate and fully charged. The battery was tested in an Accelerating Rate Calorimeter (ARC) under conditions of elevated temperature to detect thermal runaway of the battery and the energy released. The results are shown in Table 1.

[0071] Example 3

[0072] A core-shell composite material with a coating layer of polyurea-formaldehyde resin and a core of magnesium peroxide is used as an oxygen release agent for lithium-ion batteries. The thermal decomposition temperature of the polyurea-formaldehyde resin is 200°C, the thickness of the coating layer is 50nm, and the diameter of the core is 600nm.

[0073] The positive electrode active material lithium iron phosphate, conductive agent Super P, binder polyvinylidene fluoride (PVDF), lithium ion battery oxygen release agent (polyurea-formaldehyde resin @MgO2) are mixed in a mass ratio of 85:3:2:10, with N-methylpyrrolidone as solvent, and stirred at a speed of 1000rpm-5000rpm for about 6 hours at 25℃±3℃ to obtain a uniform and stable positive electrode active slurry with a single surface density of 1.68g / dm 3The positive electrode current collector is coated on both sides with the lithium ion battery oxygen releasing agent, and after baking, rolling and cutting, a positive electrode sheet containing the lithium ion battery oxygen releasing agent is obtained. The separator is a PP separator with a thickness of 20 μm, and the negative electrode uses graphite as the negative electrode active material. After lamination, shell insertion, tab welding, vacuum baking of the dry cell at 80°C, injection of about 250 g of carbonate electrolyte, the solvent of the electrolyte is a volume ratio of 1:1:1 of methyl ethyl carbonate (EMC), diethyl carbonate (DMC) and ethylene carbonate (EC), and the solute is 1 mol / L of LiPF6. After 48 h of soaking at 45°C, pre-charging, 48 h of aging at 45°C, negative pressure exhaust and sealing of the liquid port, the target cell is obtained. The target cell is cycled 3 times at 0.5C rate and fully charged. The battery is tested in an Accelerating Rate Calorimeter (ARC) to detect the thermal runaway of the battery and the energy released under temperature rise. The results are shown in Table 1.

[0074] Example 4

[0075] The core-shell structure composite material with polyurea-formaldehyde resin as the coating layer and magnesium peroxide as the inner core is used as the lithium ion battery oxygen releasing agent polyurea-formaldehyde resin@MgO2. The thermal decomposition temperature of the polyurea-formaldehyde resin is 200°C, the thickness of the coating layer is 50 nm, and the diameter of the inner core is 600 nm.

[0076] The positive electrode active material lithium iron phosphate, the conductive agent Super P, the binder polyvinylidene fluoride (PVDF) and the lithium ion battery oxygen releasing agent (polyurea-formaldehyde resin@MgO2) are mixed in a mass ratio of 92:3:2:3, N-methyl pyrrolidone is used as the solvent, and the mixture is stirred at a speed of 1000 rpm-5000 rpm for about 6 hours under the condition of 25°C±3°C to obtain a uniform and stable positive electrode active slurry. The positive electrode active material is coated on the positive electrode current collector to obtain a positive electrode sheet containing the lithium ion battery oxygen releasing agent. 3 The positive electrode current collector is coated on both sides with the lithium ion battery oxygen releasing agent, and after baking, rolling and cutting, a positive electrode sheet containing the lithium ion battery oxygen releasing agent is obtained. The negative electrode active material graphite, the conductive agent Super P, CMC, SBR, the lithium ion battery oxygen releasing agent (polyurea-formaldehyde resin@MgO2) are mixed in a mass ratio of 92.5:1.5:1.2:1.8:3, deionized water is used as the solvent, and the mixture is stirred at a speed of 800 rpm-4000 rpm for about 10 hours under the condition of 25°C±3°C to obtain a uniform and stable negative electrode active slurry. The negative electrode active material is coated on the negative electrode current collector to obtain a negative electrode sheet containing the lithium ion battery oxygen releasing agent. 3The double-sided coating is applied on the negative current collector, and after baking, rolling and cutting, a negative electrode sheet containing lithium ion battery oxygen releasing agent is obtained. The separator is a PP separator with a thickness of 20 μm, and after lamination, shell insertion, tab welding, vacuum baking of dry battery at 80℃, injection of about 250 g of carbonate electrolyte, the solvent of the electrolyte is a volume ratio of 1:1:1 of methyl ethyl carbonate (EMC), diethyl carbonate (DMC) and ethylene carbonate (EC), and the solute is 1 mol / L of LiPF6. After 48 h of infiltration at 45℃, pre-charging, 45℃ aging for 48 h, negative pressure exhaust, and liquid port sealing, the target battery is obtained. The target battery is cycled 3 times at 0.5C rate and fully charged. The battery is tested in an accelerating rate calorimeter (ARC) to detect the thermal runaway of the battery under temperature rise and the energy released by the battery. The results are shown in Table 1.

[0077] Example 5

[0078] A composite material with a polyurea-formaldehyde resin coating layer and a magnesium peroxide core as a core-shell structure is used as a lithium ion battery oxygen releasing agent polyurea-formaldehyde resin@MgO2. The thermal decomposition temperature of the polyurea-formaldehyde resin is 200℃, the thickness of the coating layer is 50 nm, and the diameter of the core is 600 nm.

[0079] The positive electrode active material lithium iron phosphate, conductive agent Super P, and binder polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 92:3:2, N-methyl pyrrolidone is used as the solvent, and the mixture is stirred at a speed of 1000 rpm-5000 rpm for about 6 hours at 25℃±3℃ to obtain a uniform and stable positive electrode active slurry. The positive electrode active material is coated on the negative electrode current collector to form a positive electrode, and the positive electrode is coated on the negative electrode to form a lithium ion battery. The battery is cycled 3 times at 0.5C rate and fully charged. The battery is tested in an accelerating rate calorimeter (ARC) to detect the thermal runaway of the battery under temperature rise and the energy released by the battery. The results are shown in Table 1. 3The positive electrode roll material is obtained after the positive electrode current collector is coated with the oxygen releasing agent and baked. The oxygen releasing agent slurry is obtained by mixing the oxygen releasing agent (polyurea-formaldehyde resin@MgO2) and the binder polyvinylidene fluoride (PVDF) at a mass ratio of 98:2, using N-methyl pyrrolidone as the solvent, stirring at a speed of 800 rpm-2500 rpm for about 2 hours under the condition of 25℃±3℃, and the oxygen releasing agent slurry is uniformly and stably obtained. The oxygen releasing agent slurry is coated on the positive electrode roll material, and the thickness of the single-side coating layer is about 1 μm. After baking, rolling and cutting, the positive electrode sheet containing the lithium ion battery oxygen releasing agent is obtained. The thickness of the PP separator is 20 μm, and graphite is used as the negative electrode active material. After the lamination, the shell is put into, the tab is welded, the dry cell is vacuum baked at 80℃, about 250g of carbonate electrolyte is injected, the solvent of the electrolyte is a volume ratio of 1:1:1 of methyl ethyl carbonate (EMC), diethyl carbonate (DMC) and ethylene carbonate (EC), the solute is 1 mol / L of LiPF6, the battery is soaked at 45℃ for 48h, the negative pressure is exhausted, the liquid port is sealed, and the target battery is obtained after the capacity is divided. The target battery is cycled for 3 times at a rate of 0.5C and is fully charged. The battery is tested in the accelerating rate calorimeter (ARC) to detect the heat runaway condition and the energy released by the battery under the condition of temperature rise, and the results are shown in Table 1.

[0080] Example 6

[0081] The core-shell structure composite material with the polyurea-formaldehyde resin as the coating layer and the magnesium peroxide as the core is used as the lithium ion battery oxygen releasing agent polyurea-formaldehyde resin@MgO2, the thermal decomposition temperature of the polyurea-formaldehyde resin is 200℃, the thickness of the coating layer is 50 nm, and the diameter of the core is 600 nm.

[0082] The difference between Example 5 and Example 6 is that the thickness of the single-side coating layer of the oxygen releasing agent slurry is about 2.5 μm.

[0083] Example 7

[0084] The core-shell structure composite material with the polyurea-formaldehyde resin as the coating layer and the magnesium peroxide as the core is used as the lithium ion battery oxygen releasing agent polyurea-formaldehyde resin@MgO2, the thermal decomposition temperature of the polyurea-formaldehyde resin is 200℃, the thickness of the coating layer is 50 nm, and the diameter of the core is 600 nm.

[0085] The difference between Example 5 and Example 6 is that the thickness of the single-side coating layer of the oxygen releasing agent slurry is about 2.5 μm.

[0086] Example 8

[0087] The core-shell structure composite material with polyurea-formaldehyde resin as the coating layer and magnesium peroxide as the inner core is used as the oxygen releasing agent polyurea-formaldehyde resin@MgO2 for lithium ion batteries, the thermal decomposition temperature of the polyurea-formaldehyde resin is 200℃, the thickness of the coating layer is 50nm, and the diameter of the inner core is 600nm;

[0088] The positive electrode active material lithium iron phosphate, the conductive agent Super P, and the binder polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 95:3:2, N-methyl pyrrolidone is used as the solvent, stirring is performed at a speed of 1000rpm-5000rpm for about 6 hours under the condition of 25℃±3℃, and a uniform and stable positive electrode active slurry is obtained. 3 The oxygen releasing agent (polyurea-formaldehyde resin@MgO2) and the binder polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 98:2, N-methyl pyrrolidone is used as the solvent, stirring is performed at a speed of 800rpm-2500rpm for about 2 hours under the condition of 25℃±3℃, and a uniform and stable oxygen releasing agent slurry is obtained. The oxygen releasing agent slurry is coated on both sides of the PP separator with a thickness of 15μm, and after baking, a composite separator coated with the oxygen releasing agent is obtained, wherein the thickness of the oxygen releasing agent coating layer is about 1μm. The composite separator is used as the battery separator, the negative electrode uses graphite active material, and after lamination, shell insertion, tab welding, and vacuum baking of the dry battery at 80℃, about 250g of carbonate electrolyte is injected, the solvent of the electrolyte is a volume ratio of 1:1:1 of methyl ethyl carbonate (EMC), diethyl carbonate (DMC), and ethylene carbonate (EC), the solute is 1mol / L of LiPF6, the battery is immersed at 45℃ for 48h, negative pressure exhaust, and the liquid inlet is sealed, and the target battery is obtained after the battery is divided. The target battery is cycled for 3 times at a rate of 0.5C and is fully charged. The battery is tested in an accelerating rate calorimeter (ARC) to detect the heat runaway condition and the energy released by the battery under the condition of temperature rise, and the results are shown in Table 1.

[0089] Example 9

[0090] The core-shell structure composite material with polyurea-formaldehyde resin as the coating layer and magnesium peroxide as the inner core is used as the oxygen releasing agent polyurea-formaldehyde resin@MgO2 for lithium ion batteries, the thermal decomposition temperature of the polyurea-formaldehyde resin is 200℃, the thickness of the coating layer is 50nm, and the diameter of the inner core is 600nm;

[0091] The difference between Example 8 and the present embodiment is that the thickness of the oxygen releasing agent coating layer is about 2μm.

[0092] Example 10

[0093] A core-shell composite material with a coating layer of polyurea-formaldehyde resin and a core of magnesium peroxide is used as an oxygen release agent for lithium-ion batteries. The thermal decomposition temperature of the polyurea-formaldehyde resin is 200°C, the thickness of the coating layer is 50nm, and the diameter of the core is 600nm.

[0094] The difference from Example 8 is that the thickness of the oxygen-releasing agent coating layer is about 3 μm.

[0095] Example 11

[0096] A core-shell composite material with a coating layer of polyurea-formaldehyde resin and a core of magnesium peroxide is used as an oxygen release agent for lithium-ion batteries. The thermal decomposition temperature of the polyurea-formaldehyde resin is 200°C, the thickness of the coating layer is 50nm, and the diameter of the core is 600nm.

[0097] The positive electrode active material lithium iron phosphate, conductive agent Super P, and binder polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 95:3:2, with N-methylpyrrolidone as solvent, and stirred at a speed of 1000-5000 rpm for about 6 hours at 25℃±3℃ to obtain a uniform and stable positive electrode active slurry with a single surface density of 1.5g / dm 3 The positive electrode is coated on both sides of the cathode current collector and then baked, rolled, and cut to obtain the positive electrode sheet. The separator uses a 20μm thick PP separator, and the negative electrode uses a graphite active material. The cells are then stacked, placed in a shell, welded to the tabs, and vacuum-baked at 80°C. Approximately 250g of carbonate electrolyte with an oxygen release agent (wherein the oxygen release agent has a mass percentage of 2%) is injected. The cells are then stacked, placed in a shell, welded to the tabs, and vacuum-baked at 80°C. Approximately 250g of carbonate electrolyte is injected. The electrolyte solvent is ethyl methyl carbonate (EMC), diethyl carbonate (DMC), and ethylene carbonate (EC) in a 1:1:1 volume ratio, and the solute is 1 mol / L LiPF6. The cells are then immersed at 45°C for 48 hours, vented under negative pressure, the injection port sealed, and the volume is divided to obtain the target cell. The target cell is cycled three times at a 0.5C rate and fully charged. The battery was tested in an Accelerating Rate Calorimeter (ARC) under conditions of elevated temperature to detect thermal runaway of the battery and the energy released. The results are shown in Table 1.

[0098] Example 12

[0099] A core-shell composite material with a coating layer of polyurea-formaldehyde resin and a core of magnesium peroxide is used as an oxygen release agent for lithium-ion batteries. The thermal decomposition temperature of the polyurea-formaldehyde resin is 200°C, the thickness of the coating layer is 50nm, and the diameter of the core is 600nm.

[0100] The difference between Example 11 and Example 14 is that the mass percentage of the oxygen releasing agent in the electrolyte is 8%.

[0101] Example 13

[0102] The core-shell structure composite material with polyurea-formaldehyde resin as the coating layer and magnesium peroxide as the core is used as the lithium ion battery oxygen releasing agent polyurea-formaldehyde resin@MgO2, the thermal decomposition temperature of the polyurea-formaldehyde resin is 200℃, the thickness of the coating layer is 50nm, and the diameter of the core is 600nm.

[0103] The difference between Example 11 and Example 14 is that the mass percentage of the oxygen releasing agent in the electrolyte is 8%.

[0104] Example 14

[0105] The core-shell structure composite material with polyurea-formaldehyde resin as the coating layer and magnesium peroxide as the core is used as the lithium ion battery oxygen releasing agent polyurea-formaldehyde resin@CaO2, the thermal decomposition temperature of the polyurea-formaldehyde resin is 200℃, the thickness of the coating layer is 50nm, and the diameter of the core is 600nm.

[0106] The positive active material lithium iron phosphate, the conductive agent Super P, the binder polyvinylidene fluoride (PVDF), and the lithium ion battery oxygen releasing agent (polyurea-formaldehyde resin@CaO2) are mixed in a mass ratio of 92:3:2:3, N-methyl pyrrolidone is used as the solvent, stirring is performed at a speed of 1000rpm-5000rpm for about 6 hours under the condition of 25℃±3℃, and a uniform and stable positive active slurry is obtained. The positive active slurry is coated on the positive current collector at a single surface density of 1.55g / dm3, and after baking, rolling, and cutting, a positive plate containing the lithium ion battery oxygen releasing agent is obtained. A PP separator with a thickness of 20μm is used as the separator, and graphite is used as the negative active material. After lamination, shell insertion, tab welding, and vacuum baking of the dry cell at 80℃, about 250g of carbonate electrolyte is injected, the solvent of the electrolyte is a volume ratio of 1:1:1 of methyl ethyl carbonate (EMC), diethyl carbonate (DMC), and ethylene carbonate (EC), the solute is 1mol / L of LiPF6, and the target cell is obtained after 48h of 45℃ soaking, pre-charge formation, 48h of 45℃ aging, negative pressure exhaust, and sealing of the liquid inlet. The target cell is cycled 3 times at a rate of 0.5C and fully charged. The battery is tested in an Accelerating Rate Calorimeter (ARC) to detect the thermal runaway of the battery and the energy released under the condition of temperature rise, and the results are shown in Table 1.

[0107] Example 15

[0108] The core-shell structure composite material with polyurea-formaldehyde resin as the coating layer and magnesium peroxide as the inner core is used as the lithium ion battery oxygen releasing agent polyurea-formaldehyde resin@MgO2, the thermal decomposition temperature of the polyurea-formaldehyde resin is 200℃, the thickness of the coating layer is 50nm, and the diameter of the inner core is 600nm;

[0109] The positive electrode active material lithium iron phosphate, the conductive agent Super P, the binder polyvinylidene fluoride (PVDF) and the lithium ion battery oxygen releasing agent (polyurea-formaldehyde resin@MgO2) are mixed in a mass ratio of 92:3:2:3, N-methyl pyrrolidone is used as the solvent, stirring is performed at a speed of 1000rpm-5000rpm for about 6 hours under the condition of 25℃±3℃, and a uniform and stable positive electrode active slurry is obtained. The positive electrode active slurry is coated on the positive electrode current collector in a single surface density of 1.55g / dm3, and after baking, rolling and cutting, a positive electrode sheet containing the lithium ion battery oxygen releasing agent is obtained. The thickness of the PP separator is 20μm, and graphite is used as the negative electrode active material. After lamination, shell insertion, tab welding, vacuum baking of the dry cell at 80℃, injection of about 250g of carbonate electrolyte, and sealing of the liquid port, the target cell is obtained. The target cell is cycled 3 times at a rate of 0.5C and fully charged. The battery is tested in an Accelerating Rate Calorimeter (ARC) to detect the thermal runaway of the battery and the energy released under the condition of temperature rise, and the results are shown in Table 1.

[0110] Comparative Example 1

[0111] The positive electrode active material lithium iron phosphate, the conductive agent and the binder are mixed in a mass ratio of 95:3:2, N-methyl pyrrolidone is used as the solvent, stirring is performed at a speed of 1000rpm-5000rpm for about 6 hours under the condition of 25℃±3℃, and a uniform and stable positive electrode active slurry is obtained. The positive electrode active slurry is coated on the positive electrode current collector in a single surface density of 1.5g / dm 3The positive electrode current collector coated with the double-sided coating was baked, rolled and cut to obtain a positive electrode sheet. The separator film was a PP separator film with a thickness of 20 pm, and the negative electrode was a graphite active material. After the steps of stacking, entering the shell, welding the tabs, vacuum baking the dry cell at 80 °C, injecting about 250 g of a carbonate electrolyte, stacking, entering the shell, welding the tabs, vacuum baking the dry cell at 80 °C, and injecting about 250 g of a carbonate electrolyte, the solvent of the electrolyte was a volume ratio of 1:1:1 of ethyl methyl carbonate (EMC), diethyl carbonate (DMC) and ethylene carbonate (EC), and the solute was 1 mol / L of LiPF6. The target cell was obtained by the steps of 45 °C soaking for 48 h, pre-charging, 45 °C aging for 48 h, negative pressure exhaust, sealing the liquid inlet, and finally, the target cell was cycled 3 times at a rate of 0.5C and fully charged. The battery was tested in an accelerating rate calorimeter (ARC) to detect the heat runaway condition and the energy released by the battery under temperature rise. The results are shown in Table 1.

[0112] Thermal abuse safety performance test

[0113] The battery cells prepared in the examples and comparative examples were tested for thermal abuse safety using an accelerating rate calorimeter. The ARC used a "heat-wait-search" mode to detect the changes in battery temperature and heat release. When the battery self-heating rate was greater than or equal to 0.02 °C / min, the ARC stopped heating, and the temperature was recorded as T0. This temperature was considered to be the starting self-heating temperature of the battery. As the battery temperature continued to rise, the SEI film decomposed and the electrolyte reacted with lithium metal, continuously releasing heat. When the battery self-heating rate was greater than or equal to 1 °C / min, the temperature was recorded as T1. This temperature was considered to be the thermal runaway temperature of the battery. From the start of battery thermal runaway to the highest temperature, the temperature was recorded as T2 until the end of thermal runaway. At the same time, the ARC obtained the energy released during the entire process.

[0114] Table 1 Thermal abuse safety performance test results of the battery cells of Examples 1-15 and Comparative Example 1

[0115]

[0116]

[0117] As can be seen from the data in Table 1, compared with the comparative example 1 without adding the lithium ion battery oxygen releasing agent, the thermal runaway maximum temperature T2 of the battery of the present application example 1 by adding the lithium ion battery oxygen releasing agent at different positions of the lithium ion battery is significantly reduced, which shows that the lithium ion battery oxygen releasing agent can effectively reduce the destructive of the battery thermal runaway and improve the safety performance of the battery. This is mainly because the lithium ion battery oxygen releasing agent releases oxygen as the battery thermal runaway temperature rises, increases the oxygen content in the electrolyte, makes the carbonate electrolyte completely oxidize, generates a large amount of fire extinguishing agent CO2, effectively alleviates the continuous development of the battery thermal runaway and significantly reduces the battery heat.

[0118] The above describes the preferred embodiments in detail, but the present application is not limited to the specific embodiments described above, and those skilled in the art can make various specific changes under the inspiration of the present application without departing from the scope of the present application, which are all within the protection scope of the present application.

Claims

1. A lithium ion battery oxygen release agent, characterized in that The lithium-ion battery oxygen release agent includes a core and a coating layer coated on the surface of the core, the core includes an inorganic oxygen-releasing chemical reagent, the coating layer includes an organic polymer, and the thermal decomposition temperature of the organic polymer is 150°C-220°C; the inorganic oxygen-releasing chemical reagent includes calcium peroxide and / or magnesium peroxide; the organic polymer includes one or more of vinylidene fluoride-hexafluoropropylene copolymer, polyurea-formaldehyde resin, and polymethyl methacrylate.

2. The lithium ion battery oxygen release agent according to claim 1, wherein The compressive strength of the organic polymer is 80 MPa-150 MPa.

3. The lithium ion battery oxygen release agent according to claim 1, wherein The diameter of the core is 100 nm-1 μm; the thickness of the coating layer is 20 nm-200 nm.

4. The lithium ion battery oxygen release agent according to claim 1, wherein In the lithium-ion battery oxygen-releasing agent, the mass ratio of the inorganic oxygen-releasing chemical agent to the organic polymer is 8-20:

1.

5. A method for preparing the lithium ion battery oxygen release agent according to any one of claims 1 to 4, comprising: An inorganic oxygen-releasing chemical reagent is added to an organic polymer solution, mixed and then dried to obtain an oxygen-releasing agent for lithium-ion batteries.

6. A lithium-ion battery, characterized in that: The lithium-ion battery comprises the lithium-ion battery oxygen releaser according to any one of claims 1 to 4.

7. The lithium-ion battery according to claim 6, wherein The lithium-ion battery includes a positive electrode sheet, a negative electrode sheet, and a separator and an electrolyte located between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet, and / or the negative electrode sheet, and / or the separator, and / or the electrolyte contain the lithium-ion battery oxygen release agent.

8. The lithium-ion battery according to claim 7, wherein The positive electrode sheet includes a positive electrode current collector and a positive electrode active layer supported on the positive electrode current collector, and the positive electrode active layer includes the lithium ion battery oxygen release agent; Alternatively, the positive electrode sheet includes a positive electrode current collector, a positive electrode active layer supported on the positive electrode current collector, and an oxygen-releasing material layer disposed on a surface of the positive electrode active layer away from the positive electrode current collector, wherein the oxygen-releasing material layer includes the lithium-ion battery oxygen-releasing agent.

9. The lithium-ion battery according to claim 7, wherein The negative electrode sheet includes a negative electrode current collector and a negative electrode active layer supported on the negative electrode current collector, and the negative electrode active layer includes the lithium ion battery oxygen release agent; Alternatively, the negative electrode sheet includes a negative electrode current collector, a negative electrode active layer supported on the negative electrode current collector, and an oxygen-releasing material layer disposed on the surface of the negative electrode active layer away from the negative electrode current collector, wherein the oxygen-releasing material layer includes the lithium-ion battery oxygen release agent.

10. The lithium-ion battery according to claim 7, wherein The mass of the lithium-ion battery oxygen release agent accounts for 3%-10% of the total mass of the positive electrode sheet and the negative electrode sheet.

11. The lithium-ion battery according to claim 7, wherein The diaphragm includes a diaphragm substrate and an oxygen-releasing material layer arranged on the diaphragm substrate. The oxygen-releasing material layer includes the lithium-ion battery oxygen-releasing agent. The thickness of the oxygen-releasing material layer is 1 μm-3 μm. The mass percentage of the lithium-ion battery oxygen-releasing agent in the diaphragm is 10%-30%.

12. The lithium-ion battery according to claim 7, wherein The mass percentage of the lithium ion oxygen-releasing agent in the electrolyte is 2%-8%.

13. An electrical device, characterized in that: The electric device includes the lithium-ion battery as claimed in claim 6.

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