Lithium secondary batteries capable of self-poisoning

Abstract

The present invention provides a lithium secondary battery capable of self-poisoning, which includes a poisoning agent that releases molecular iodine within the lithium secondary battery. The unstable lithium atoms in the lithium secondary battery are converted into stable lithium compounds or lithium ions before the lithium secondary battery reaches an abnormally high temperature caused by the lithium secondary battery itself, and the negative electrode active material of the lithium secondary battery is deactivated to avoid thermal runaway of the lithium secondary battery.

Description

[Technical Field]

[0001] The present invention relates to a lithium secondary battery, and more particularly to a lithium secondary battery capable of self-poisoning before reaching an abnormally high temperature caused by the battery itself, in order to improve the safety of the lithium secondary battery. [Background technology]

[0002] Lithium-ion batteries are widely used in a variety of products, such as vehicles, wearable products for consumer and industrial applications, portable devices, and energy storage devices, and thus find application in almost every area of ​​human daily life. However, we occasionally hear about accidents involving lithium-ion batteries, such as fires and explosions in mobile phone batteries and electric vehicles. All of this is due to the fact that a comprehensive and effective solution to the safety issues of lithium-ion batteries is still lacking.

[0003] The main cause of the risk of fire or explosion in lithium secondary batteries is thermal runaway. The primary cause of thermal runaway in lithium batteries is heat, which is an exothermic reaction resulting from high-temperature-induced thermal decomposition of the battery's SEI (solid electrolyte interface) film, electrolyte, binder, and positive and negative active materials. Current methods for suppressing thermal runaway can be classified into two types depending on where the safety mechanism is activated: outside the lithium secondary battery and inside the lithium secondary battery. In the case of external lithium secondary batteries, a monitoring system using digital calculation simulation is used. In the case of the type inside the lithium secondary battery, it can be further divided into physical methods and chemical methods. The digital monitoring system for the exterior of the lithium secondary battery utilizes a dedicated protection circuit and a dedicated management system for the exterior of the lithium secondary battery to enhance the safety monitoring of the battery during the use process. In the case of a physical type separator inside a lithium secondary battery, such as a thermal shutdown separator, when the battery cell becomes hot, the pores of the separator close and block the passage of ions. The chemistry type inside the lithium secondary battery can be defined as scale control type or electrochemical reaction type. In the scale control type, a flame retardant is added to the electrolyte to control the scale caused by thermal runaway. Examples of electrochemical reaction types are as follows: 1) Adding a monomer or oligomer to the electrolyte causes polymerization as the temperature rises, slowing down the ion migration rate. Therefore, the ionic conductivity decreases with increasing temperature, slowing down the electrochemical reaction rate in the lithium secondary battery. 2) A positive temperature coefficient (PTC) resistance material is sandwiched between the positive electrode layer or negative electrode layer and the adjacent current collecting layer. As the temperature of a lithium secondary battery increases, the electrical insulation ability is strengthened. This reduces the power transmission efficiency between the positive electrode layer or negative electrode layer and the adjacent current collecting layer, and also reduces the electrochemical reaction rate. 3) A modified layer forms on the surface of the positive electrode active material. As the temperature of the battery cell increases, the modified layer transforms into a dense film, which increases the resistance to charge transfer and slows down the electrochemical reaction rate.

[0004] However, the above-mentioned methods are aimed only at passively blocking ion / electron transfer pathways to reduce heat generation, and do not aim to eliminate thermal runaway by targeting the principle that causes it.

[0005] Therefore, the present invention provides a lithium secondary battery capable of self-poisoning, which aims to solve the problem of thermal runaway in lithium secondary batteries by converting highly active lithium atoms in the lithium secondary battery into stable lithium compounds or lithium ions. Summary of the Invention [Problem to be solved by the invention]

[0006] The main object of the present invention is to provide a lithium secondary battery capable of self-poisoning, which contains a poisonous agent that releases molecular iodine into the lithium secondary battery. When the temperature of the lithium secondary battery reaches a first predetermined temperature, the iodine molecules react with the highly active lithium atoms to produce stable lithium compounds or lithium ions. The negative electrode active material of the lithium secondary battery is inactivated to achieve harmlessness of the lithium secondary battery and avoid thermal runaway. [Means for solving the problem]

[0007] To achieve this, the present invention discloses a lithium secondary battery capable of self-poisoning, which includes a positive electrode active material, a negative electrode active material containing lithium atoms, an electrolyte located between the positive electrode active material and the negative electrode active material and allowing lithium ions to move between the positive electrode active material and the negative electrode active material, and a poisoning agent containing an iodine molecule donor that releases iodine molecules into the lithium secondary battery. Furthermore, at a first predetermined temperature, the iodine molecules react with the negative electrode active material to form stable lithium compounds or lithium ions from the highly active lithium atoms, rendering the lithium secondary battery harmless. The first predetermined temperature is 80°C or higher.

[0008] The following details of specific embodiments are presented to facilitate understanding of the objectives, technical contents, features and effects of the present invention. [Brief explanation of the drawings]

[0009] [Figure 1(a)] FIG. 1 is a flow chart showing the poisoning process of a lithium secondary battery capable of self-poisoning according to the present invention. [Figure 1(b)] FIG. 2 is another flow diagram illustrating the poisoning process of the self-poisoning capable lithium secondary battery of the present invention. [Figure 2] 1 is a schematic diagram of an embodiment of the present invention in which a poison agent is disposed within a lithium secondary battery. [Figure 3] 1 is a schematic diagram of an embodiment of the present invention in which a poison agent is disposed within a lithium secondary battery. [Figure 4] 1 is a schematic diagram of an embodiment of the present invention in which a poison agent is disposed within a lithium secondary battery. [Figure 5] 1 is a schematic diagram of an embodiment of the present invention in which a poison agent is disposed within a lithium secondary battery. [Figure 6] 1 is a schematic diagram of an embodiment of the present invention in which a poison agent is disposed within a lithium secondary battery. [Figure 7] 1 is a schematic diagram of an embodiment of the present invention in which a poison agent is disposed within a lithium secondary battery. [Figure 8] 1 is a schematic diagram of an embodiment of the present invention in which a poison agent is disposed within a lithium secondary battery. [Figure 9] 1 is a schematic diagram of an embodiment of the present invention in which a poison agent is disposed within a lithium secondary battery. [Figure 10] 1 is a schematic diagram of an embodiment of the present invention in which a poison agent is disposed within a lithium secondary battery. [Figure 11] 1 is a schematic diagram of an embodiment of the present invention in which a poison agent is disposed within a lithium secondary battery. [Figure 12] 1 is a schematic diagram of an embodiment of the present invention in which a poison agent is disposed within a lithium secondary battery. [Figure 13] 1 is a schematic diagram of an embodiment of the present invention in which a poison agent is disposed within a lithium secondary battery. [Figure 14] FIG. 1 is a schematic diagram of an embodiment of the present invention in which a poison agent is disposed within the negative electrode active material. DETAILED DESCRIPTION OF THE INVENTION

[0010] In order to make the advantages, spirit, and features of the present invention more clearly understandable, the present invention will be described in detail below using examples. Note that these examples are merely representative examples of the present invention, and the embodiments and scope of the claims of the present invention are not limited to these examples. The following examples are intended to make the contents of the present invention clearer and easier to understand.

[0011] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the general inventive concepts. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the exemplary embodiments belong. Furthermore, it should be understood that terms defined in commonly used dictionaries should be construed to have a meaning that is consistent with their meaning in the relevant art, and should not be construed in an idealized or overly formal sense unless expressly defined in the specification.

[0012] Throughout this specification, reference to "one embodiment or a specific embodiment" means that the particular feature, structure, material, or characteristic described in connection with that embodiment is included in at least one embodiment of the invention. Thus, the appearances of the phrase "in one embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, and may be. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments.

[0013] In the following description, the first predetermined temperature is defined as the reaction temperature at which iodine molecules and lithium atoms form stable lithium compounds or lithium ions. The second predetermined temperature is defined as the temperature at which molecular iodine is released. The third predetermined temperature is defined as a reaction temperature between the second reaction trigger and the first reaction trigger, and is lower than the second predetermined temperature.

[0014] The present invention relates to a lithium secondary battery capable of self-poisoning, and includes a positive electrode active material, a negative electrode active material, an electrolyte, and a poisoning agent. The negative electrode active material contains lithium atoms and is highly active but unstable compared to the positive electrode active material. For example, the matrix of the negative electrode active material is lithium metal, a material such as silicon that can form an alloy with lithium, or a composite negative electrode active material having a layered structure composed of a plurality of silicon particles and carbon particles. A preferable condition is that the negative electrode active material is a mixture of a crystalline state and an amorphous state, and the amorphous portion occupies 10% or more of the total volume. The optimum particle size of the silicon particles and carbon particles is 1 nm to 10 nm, and generally at least 100 nm or less. The negative electrode active material in which silicon particles and carbon particles are layered is produced by chemical vapor deposition. The particle size can be measured using an electron microscope (EM), such as a transmission electron microscope (TEM) or a scanning electron microscope (SEM). The electrolyte is located between the positive electrode active material and the negative electrode active material, thereby allowing lithium ions to move between the positive electrode active material and the negative electrode active material. The poison agent contains a molecular iodine donor for releasing molecular iodine at a second predetermined temperature. Therefore, when the temperature of the lithium secondary battery reaches or approaches the first predetermined temperature, the poisoning agent causes the highly active lithium atoms to start forming stable lithium compounds or lithium ions. As a result, the negative electrode active material of the lithium secondary battery is inactivated, achieving the so-called "harmlessness" of the lithium secondary battery and avoiding thermal runaway. Here, the first predetermined temperature is above 100°C, preferably above 120°C. The second temperature may be lower or higher than the first preset temperature, depending on the form of the molecular iodine donor. The stable lithium compounds referred to herein can be, for example, but not limited to, lithium iodide, lithium fluoride, lithium iodide compounds or lithium fluoride compounds. It is well known that the electrochemical system of a lithium secondary battery has a very complicated multi-component structure, and the reactions that occur at the first predetermined temperature, which is a relatively high temperature, are also relatively complicated. Thus, the stable lithium compounds described herein are relative to the lithium atom of higher activity and are not limited to lithium iodide, lithium fluoride, lithium iodide compounds or lithium fluoride compounds. It can also be said that lithium compounds are anaerobic, non-flammable, and stable at temperatures below 300°C. When the negative electrode active material is lithium metal, it is in the form of a thin sheet.

[0015] Furthermore, since the atoms of the iodine component are larger than the lithium atoms, it is more difficult for the iodine molecules to enter the negative electrode structure and form lithium compounds or lithium ions with the lithium atoms in negative electrodes that undergo lithium insertion / extraction, such as graphite, hard carbon, or soft carbon. This means that the poisoning agent of the present invention is less effective in this type of negative electrode.

[0016] 1(a), which is a flow diagram illustrating the poisoning process of the self-poisoning capable lithium secondary battery of the present invention. The molecular iodine donor used in this embodiment releases molecular iodine at a temperature lower than a first predetermined temperature. First, in step S11, a lithium secondary battery containing the poison agent is provided. Next, in step S12, when the temperature of the lithium secondary battery rises to a second predetermined temperature, the molecular iodine donor is triggered or starts to form or supply molecular iodine within the lithium secondary battery. In step 13, the poisoning process begins when the temperature of the lithium secondary battery rises to a first predetermined temperature. The iodine molecules react with the negative electrode active material containing lithium atoms in the lithium secondary battery, converting the lithium atoms into stable lithium compounds or lithium ions, thereby damaging the lithium secondary battery and avoiding thermal runaway. In the above steps S11 and S12, the lithium secondary battery is a battery that can be normally charged and discharged. Furthermore, it can be said that the lithium secondary battery is in a discharged state before it is rendered inoperable (damaged) in step S13. For example, the discharge state may be caused by an external object puncture. Based on the first and second predetermined temperatures being the temperatures of the lithium secondary battery itself, it can be said that the initiation of self-poisoning and invalidation is completed by the lithium secondary battery itself. The first predetermined temperature is 80° C. or higher, but is lower than the initiation temperature that triggers thermal runaway of the lithium secondary battery caused by an abnormal temperature rise in the lithium secondary battery itself. For example, the breakdown temperature of the polymer separator is 120°C to 150°C, and the thermal runaway temperature of the negative electrode is 200°C to 250°C. Therefore, the first predetermined temperature is above 80°C, preferably above 100°C, but below 170°C. Due to the breakdown temperature of the polymer separator, the present invention is believed to be more suitable for application to lithium secondary batteries in which the separator is an oxide material. The oxide material may or may not allow lithium ion migration.

[0017] 1(b), which is another flow diagram illustrating the poisoning process of the self-poisoning capable lithium secondary battery of the present invention. The molecular iodine donor used in this embodiment releases molecular iodine at a temperature close to or slightly higher than a first predetermined temperature. Therefore, the second predetermined temperature is equal to or higher than the first predetermined temperature. First, in step S21, a lithium secondary battery containing the poison agent is provided. Next, in step S22, when the temperature of the lithium secondary battery rises to a second predetermined temperature, the molecular iodine donor is triggered or starts to form or supply molecular iodine within the lithium secondary battery. Furthermore, in step S23, the temperature of the lithium secondary battery is equal to or higher than the first predetermined temperature. Thus, the released iodine molecules attack the lithium atoms, carrying out the poisoning process. The lithium atoms are converted into stable lithium compounds or lithium ions, destroying the lithium secondary battery.

[0018] Furthermore, the lithium secondary battery capable of self-poisoning of the present invention can have two types of structures. The first structure is a structure in which the electrolyte of the lithium secondary battery does not require a polar medium. Here, the polar medium refers to a polar solution or a polymer having a polar functional group. The second structure is one in which the electrolyte of the lithium secondary battery requires a polar medium.

[0019] First, the first structure will be explained. In the first structure, the iodine molecule donor in the poison is 1) Pure iodine - provides molecular iodine in gaseous form by sublimation; 2) Pure iodine adsorbed porous adsorbent material - can be activated carbon, graphene, zeolite or carbon tubes; 3) iodide, 4) iodine-oxygen derivative, or a mixture of at least two or more of the above four types of molecular iodine donors.

[0020] Furthermore, in the first structure, since there is no polar medium, the electrolyte of the lithium secondary battery is in the form of an inorganic solid electrolyte, for example, a sulfide solid electrolyte, an oxide solid electrolyte, or a metal halide solid electrolyte. In this configuration, the inorganic solid electrolyte can function as a separator in a lithium secondary battery to separate the positive electrode active material from the negative electrode active material. The inorganic solid electrolyte includes both a crystalline state and an amorphous state. In this structure, iodine molecules are transported in a gaseous state to the negative electrode active material, and lithium atoms are converted into lithium compounds at a first predetermined temperature to achieve stabilization. In this configuration, since a non-polar medium is used, the iodine molecules do not dissociate into iodide ions. Therefore, a lithium iodine battery is not formed within the lithium secondary battery, and the lithium secondary battery can continue to operate normally and safely while preventing the performance from being reduced due to the presence of a lithium iodine battery. Furthermore, since iodine molecules are in a gaseous state, they can be transported to the negative electrode active material through pores such as pores in the inorganic solid electrolyte in the lithium secondary battery. Furthermore, when the temperature of the lithium secondary battery rises, it generates the energy necessary to form the lithium iodide compound, which reacts to deactivate the lithium atoms. The oxide solid electrolyte is selected from lithium aluminum titanium phosphate (LATP), lithium aluminum germanium phosphate (LAGP), lithium lanthanum zirconium oxide (LLZO), LiAlSiO4 and other oxide solid electrolytes.

[0021] The iodide is selected from manganese iodide, copper iodide, cuprous iodide, magnesium iodide, calcium iodide, ammonium iodide, aluminum iodide, hydrogen iodide, or a mixture of two or more of the foregoing materials. Iodine-oxygen derivatives include iodic acid (HIO3), periodic acid (HIO4), iodine oxide (XOI), iodate (XIO3), periodate (XIO4), and iodate hydride (X m H n (IO3)2), periodate hydride (X m H n (IO6)), or a compound comprising a mixture of two or more of said materials. The X is a metal element, m≧1, and n≧1. The compound having iodate is iodate, lithium iodate, barium iodate, strontium iodate, calcium iodate, iron iodate, bismuth iodate, manganese iodate, nickel iodate, or an iodate precursor, such as iodine pentoxide (IO).

[0022] When an iodine-oxygen derivative is used as the molecular iodine donor, the poison agent of the present invention further comprises at least one first reaction trigger for enabling the iodine-oxygen derivative to release molecular iodine at a second predetermined temperature. Thus, by controlling the second predetermined temperature at which the first reaction trigger reacts with the iodine-oxygen derivative, the relative relationship between the second predetermined temperature and the first predetermined temperature can be adjusted. Preferably, the second predetermined temperature is selected to be no lower than said first predetermined temperature, so that the released iodine molecules can react directly with the lithium atoms. The first reaction trigger is selected from 1) a compound capable of providing a sulfur-oxygen bond with a free radical; 2) a compound capable of forming a benzoic acid or a phthalic acid isomer; 3) a compound capable of forming a hydrohalic acid; 4) a compound capable of forming boron trifluoride, or a mixture of two or more of the foregoing materials. The structure of the sulfur-oxygen bond with a free radical is

[0023] [ka] It could be.

[0024] The sulfur-oxygen bond may be located at the free end of a compound such as sodium trifluoromethanesulfinate (CF3SO2Na), perfluorobutanesulfonic acid (C4F9SO3H), sodium perfluorobutanesulfonate (C4F9SO3Na), or potassium perfluorobutanesulfonate (C4F9SO3K). Sulfur-oxygen bonds can also be present in compound structures, such as LiFSi (lithium bis(fluorosulfonyl)imide) or its sodium salt, F—(SO2)—N - -(SO2)-FM + (wherein M represents lithium or sodium),

[0025] [ka] These include peroxydisulfate, potassium peroxydisulfate, and sodium peroxydisulfate. In the case where the sulfur-oxygen bond is not exposed at a free end, a second reaction trigger, such as a boron fluoride compound, an aluminum halide compound, or a hydrogen halide compound, can be added to cleave the bond at the sulfur-oxygen bond side at a third predetermined temperature, so that the sulfur-oxygen bond has a free radical that reacts with the iodine-oxygen derivative to release molecular iodine. The borofluoride compound may be potassium tetrafluoroborate (KBF4), sodium tetrafluoroborate (NaBF4), or ammonium tetrafluoroborate (NH4BF4), or the like. The aluminum halide compound can be aluminum chloride (AlCl3) or aluminum bromide (AlBr3), or the like. The hydrogen halide compound may be hydrofluoric acid, which may be generated from lithium hexafluorophosphate (LiPF) in a heated environment, and the third predetermined temperature is equal to or lower than the second predetermined temperature. However, this may not always be the case for a second reaction trigger. For example, the aforementioned LiFSi (lithium bis(fluorosulfonyl)imide) can react directly with iodine-oxygen derivatives to release molecular iodine.

[0026] for example,

[0027] [ka] The first compound having the structure of is selected from the group consisting of sodium octyl sulfate, sodium hexyl sulfate, sodium ethyl sulfate, sodium 1-octanesulfonate monohydrate, sodium 1-octanesulfonate, sodium 1-heptanesulfonate, sodium hexanesulfonate, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, sodium 2-ethylhexyl sulfate, sodium ethyl sulfate, potassium nonafluoro-1-butanesulfonate, trifluoromethanesulfonyl chloride, 4-(3-butyl-1-imidazolio)-1-butanesulfonate, 3-(1-pyridinio)-1-propanesulfonate, dimethyl-2-hydroxyethylammonium propanesulfonate, 3-(decyldimethylammonio)propanesulfonate The compound may be an inner salt, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide, 1-ethyl-3-methylimidazolium ethyl sulfate, trifluoromethanesulfonate copper(I)-benzene complex, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, 1-fluoropyridinium triflate, 4-formyl-1-methylpyridinium benzenesulfonate, 3-hydroxynaphthalene-2,7-disulfonic acid disodium salt, benzene-1,2-disulfonate potassium, lithium trifluoromethanesulfonate, potassium trifluoromethanesulfonate, sodium bisulfite solution, sodium metabisulfite, sodium thiosulfate, sodium 1-butanesulfonate, potassium diphenylsulfonesulfonate, heptadecafluorooctanesulfonic acid potassium salt, or a mixture of two or more of the foregoing materials.

[0028] for example,

[0029] [ka] The first compound having the structure may be phenyl vinyl sulfoxide, propyl sulfoxide, methyl phenyl sulfoxide, diisobutyl sulfoxide, dodecyl methyl sulfoxide, benzyl phenyl sulfoxide, dimethyl sulfite, benzenesulfinic acid sodium salt, sodium methanesulfinate, sodium p-toluenesulfinate, sodium bisulfite solution, or a mixture of two or more of the foregoing materials.

[0030] for example,

[0031] [ka] may be 4-(trifluoromethyl)benzenesulfonyl chloride, 4-chlorobenzenesulfonyl chloride, 3-(trifluoromethyl)benzenesulfonyl chloride, 4-fluorobenzenesulfonyl chloride, trifluoromethanesulfonic anhydride, methanesulfonyl chloride, p-toluenesulfonyl chloride, 4-toluenesulfonyl chloride, 3-hydroxynaphthalene-2,7-disulfonic acid disodium salt, isobutanesulfonyl chloride, cyclohexanesulfonyl chloride, 4-methoxybenzenesulfonyl chloride, 4-bromobenzenesulfonyl chloride, 4-(trifluoromethyl)benzenesulfonyl chloride, 4-iodobenzenesulfonyl chloride, 4-fluorobenzenesulfonyl chloride, 4-nitrobenzenesulfonyl chloride, biphenyl-4-sulfonyl chloride, biphenyl-4,4'-disulfonyl chloride, 4-(aminosulfonyl)benzenesulfonyl chloride, or a mixture of two or more of the foregoing materials.

[0032] When the second form of the first reaction trigger of the present invention is selected from compounds capable of forming benzoic acid or phthalic acid isomers, the compound may be a compound having isophthalic acid, orthophthalic acid, or terephthalic acid. For example, precursors to polyimides (PI) can provide benzoic acid isomers.

[0033] A third form of the first reaction trigger of the present invention is a compound capable of releasing a hydrohalic acid, the compound being selected from hydrofluoric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, or a mixture of two or more of the foregoing materials. For example, when the compound capable of releasing a hydrohalic acid is hydrofluoric acid, it can be lithium hexafluorophosphate (LiPF), sodium hexafluorophosphate (NaPF), potassium hexafluorophosphate (KPF), ammonium hexafluorophosphate (NHPF), lithium tetrafluoroborate (LiBF), potassium tetrafluoroborate (NaBF), potassium tetrafluoroborate (KBF), or ammonium tetrafluoroborate (NHBF). When it is hydroiodic acid that releases a hydrohalic acid, the compound capable of releasing a hydrohalic acid can be LiPI. When it is hydrobromic acid that releases hydrohalic acid, the compound capable of releasing hydrohalic acid can be LiPBr6. When the second reaction trigger is a hydrohalic acid, it can also be selected from the above compounds.

[0034] A fourth form of the first reaction trigger of the present invention is a compound capable of releasing boron trifluoride (BF3). This compound can be lithium tetrafluoroborate (LiBF4), sodium fluoroborate (NaBF4), potassium fluoroborate (KBF4), or ammonium fluoroborate (NH4BF4), or the like, or a mixture of two or more of the foregoing materials.

[0035] In operation, at least two or more of the first reaction triggers described above may be mixed and used together.

[0036] Additionally, the outer surface of the molecular iodine donor may also have a pyrolytic coating layer to control the temperature at which the molecular iodine is released. For example, in the first structure, when the iodine molecular donor in the poison agent is pure iodine, pure iodine sublimes more easily. Therefore, by forming a pyrolytic coating layer on the surface of the molecular iodine donor, the second predetermined temperature at which the molecular iodine donor releases gaseous molecular iodine can be controlled.

[0037] The second structure of the present invention requires a polar medium. That is, the electrolyte of the lithium secondary battery belongs to the type of polar solution or polymer having polar functional groups. Thus, the electrolyte of a lithium secondary battery can be a liquid electrolyte, an organic solid electrolyte, or a mixed electrolyte formed by mixing particles of an inorganic solid electrolyte with at least one of the liquid electrolyte or the organic solid electrolyte. The liquid electrolyte may be in a gel or jelly state, and is a mixture of a polar solution and a polymer to provide viscosity. Liquid electrolytes can be classified as gel or jelly-like depending on the polymer content and viscosity. The viscosity of the jelly state is greater than the viscosity of the gel state. Organic solid electrolytes are prepared by using polymers as matrices. Polymers with highly polar functional groups react with metal salts to undergo Lewis acid / base reactions, resulting in successive complexation and decomplexation reactions to transport lithium ions. When the amount of plasticizer having a polar functional group in an organic solid electrolyte is large, the organic solid electrolyte is called a gel polymer electrolyte.

[0038] When the electrolyte has a polar solvent or a polar functional group, the lithium secondary battery further includes a separator that allows the electrolyte to pass through, and is disposed between the positive electrode and the negative electrode. The separator material may be a ceramic separator mainly made of oxide powder, and the oxide may be an oxide solid electrolyte capable of transferring lithium ions, such as LATP, LAGP, LLZO, or LiAlSiO4, or an oxide not capable of transferring lithium ions, such as aluminum oxide.

[0039] In the second structure, the molecular iodine donor must avoid materials that release molecular iodine at temperatures below 80°C. This is to prevent iodine molecules from prematurely dissociating into iodine ions in polar solutions or polar functional polymers, which could result in the formation of a lithium-iodine battery within the lithium secondary battery and damage to the normally and safely operating lithium secondary battery. In this structure, the molecular iodine donor may be selected from iodides or iodine oxides that do not melt and release molecular iodine at temperatures of 80°C or lower, or the pyrolytic coating layer may be formed on the surface of the molecular iodine donor. Furthermore, in the second structure, some iodine molecules are released and then contact a polar medium to form iodide ions, which then react with iodine molecules to form triiodide anions. When the lithium secondary battery is in a discharged state, the anions are moved to the negative electrode, transferring the iodine molecules to the negative electrode active material, thereby improving the reaction efficiency between the iodine molecules and the lithium atoms.

[0040] In the above two structures, when the molecular iodine donor is an iodine-oxygen derivative, the higher temperature for releasing molecular iodine, i.e., the second predetermined temperature, can be achieved by the presence of the first reaction trigger or the second reaction trigger. This is compared to pure iodine, a porous adsorbent material with pure iodine adsorbed, and a molecular iodine donor using iodide.

[0041] In the first structure of the second structure of the present invention, components with the same name can be selected from the same materials. For example, any material examples of the iodine-oxygen derivatives, the first reaction trigger, and the second reaction trigger described in the second structure can refer to the relevant descriptions in the first structure, and therefore, repeated descriptions will be omitted.

[0042] Next, various embodiments of the poisoning agent provided in the lithium secondary battery according to the present invention will be described. These embodiments can be divided into two main types. In the first type, the poison agent does not come into contact with the electrolyte of the lithium secondary battery. The material of the iodine molecule donor of the poison agent is not limited by the type of electrolyte. The second type is one in which the toxic agent comes into contact with the electrolyte. In this case, the material selected for the molecular iodine donor is limited by the difference in the type of electrolyte.

[0043] In a first form in which the poison is not in contact with the electrolyte of the lithium secondary battery, the poison can be arranged on the outside of the lithium secondary battery. A lithium secondary battery has a channel that can connect the external environment of the lithium secondary battery to the electrochemical reaction system (positive electrode active material, negative electrode active material, and electrolyte) of the lithium secondary battery. The channel may be pre-formed and exhibit a closed state when a set temperature is not reached, the set temperature being less than or equal to a first predetermined temperature. Alternatively, the channels may not be pre-formed, but may be formed by some means or reaction, such as etching, or the pressure of gases generated during the electrochemical reaction process that ruptures a sealed package component (such as a shell) of the electrochemical reaction system to form the channels.

[0044] For example, as shown in FIG. 2, the toxic agent of the present invention may be disposed on the outer surface of a current collector 201 . At least a plurality of portions of the current collector 201 are made of a copper material, and the current collector functions as a part of the packaging component of the electrochemical reaction system of the lithium secondary battery 20 . When the temperature of the lithium secondary battery reaches or approaches the temperature at which the poisoning agent releases molecular iodine, the molecular iodine released by the molecular iodine donor reacts with the copper material to form a copper iodide compound. Due to the fluctuation in the amount of copper iodide crystals, the current collector 201 is destroyed, and a plurality of holes are formed that penetrate the current collector 201 and connect to the inside of the lithium secondary battery 20 . The poison 10 can continuously enter the lithium secondary battery 20 and attack the negative electrode active material 202 adjacent to the current collector 201. The lithium atoms of the negative electrode active material 202 are converted into stable lithium compounds or lithium ions, thereby realizing safety.

[0045] Additionally, molecular iodine can react with copper to form porous, fluffy copper iodide. Thus, when the poison agent of the present invention reacts with copper current collector 201, copper current collector 201 changes from a conductive state to an insulating state, effectively terminating the electron transfer pathway at the same time. Furthermore, the surface of the poison 10 can be covered with an etching direction limiter 12 for limiting the direction in which the poison 10 is released. The material of the etching direction limiter 12 can be selected from passivated metals, glasses or polymers that do not react with iodine molecules. The position of the etching direction limiter 12 on the surface of the poison 10 can be adjusted as needed.

[0046] Furthermore, as shown in FIG. 3, auxiliary grooves 203 may be formed on the surface of the current collector 201 to facilitate etching. Furthermore, as shown in FIG. 4, the poison 10 may be sandwiched between the copper current collectors 201 of two lithium secondary batteries 20.

[0047] Furthermore, the lithium secondary battery of FIG. 3 includes a positive electrode active material 204, an aluminum current collector 205 adjacent to the positive electrode active material 204, a separator 206 (which has ion conductivity and electronic insulation properties) located between the positive electrode 204 and the negative electrode 202, and a glue frame 207 sandwiched between the aluminum current collector 205 and the copper current collector 201. The glue frame, together with the current collector 205 and the current collector 201, functions as a packaging member for the lithium secondary battery 20 and forms an enclosed space for accommodating an electrochemical reaction system constituted by the positive electrode active material 204, the separator 206, the negative electrode active material 202, etc. The lithium secondary battery 20 further includes an electrolyte system that is located within the enclosed space and provides for ionic transfer between the positive electrode active material 204 and the negative electrode active material 202 . Furthermore, if the electrolyte system is selected from a solid electrolyte form, the electrolyte system can function directly as a separator.

[0048] Furthermore, as shown in FIG. 4, an etching direction limiter 12 may be further provided around the poison 10, which can not only effectively limit the etching direction of the poison 10 and prevent overflow in an ineffective direction, but also prevent the poison 10 from being affected by the external environment.

[0049] In another embodiment, as shown in FIG. 5 , the current collector 201 has a plurality of through-holes 208, and the through-holes 208 are filled with a filler 13, such as a hot melt material (TPM) or a thermally decomposable material, that can melt or depolymerize at a first predetermined temperature to form a path that communicates with the negative electrode active material 202.

[0050] Please refer to FIG. 6, which is another embodiment of the present application. In this embodiment, the open side surface of the current collector 201 has a plurality of recesses 209 for receiving the poison agent 10 . This settling of the current collector 201 reduces the thickness of the current collector 201 that is etched. In another embodiment, as shown in FIG. 7, a plurality of etching direction limiters 32 are provided on the surface of the current collector 201 to form recesses 209 for containing the poison 10 to limit the etching direction and prevent overflow in ineffective directions. In this case, the poison agent 10 of the present invention is disposed outside the packaging components of the lithium secondary battery 20, and therefore does not affect the efficiency or composition structure of the lithium secondary battery 20.

[0051] The main difference between the lithium secondary battery 22 shown in FIG. 8 and the lithium secondary battery 20 is that the current collector 205 is coated on both sides with active material and functions as the positive electrode active material 204 .

[0052] In the second form in which the lithium secondary battery deactivator is in contact with the electrolyte, the lithium secondary battery can be in any structural form. For example, lithium secondary batteries having wound electrode layers, lithium secondary batteries having a cylindrical metal shell as a package structure, prismatic lithium secondary batteries, or sheet-type lithium secondary batteries having a current collector that functions as part of the package structure as shown in FIG. 2. In this state, the poison is placed in a position where it can come into direct contact with the electrolyte. The molecular iodine supplier of the poison needs to be adjusted depending on whether the electrolyte contains a polar medium or not, as described above. The poison may be placed anywhere in the electrochemical reaction system of the lithium secondary battery. For example, the poison may be mixed between the positive electrode current collector and the positive electrode active material, within the positive electrode active material, between the positive electrode active material and the inorganic solid electrolyte, or between the inorganic solid electrolyte and the negative electrode active material. Furthermore, if the lithium secondary battery has a separator, the poison may be disposed in the separator 206 as shown in FIG. The separator 206 may be a ceramic separator. Alternatively, as shown in FIG. 10, the poison agent 10 of the present invention may be disposed on the surface of a current collector 201 that contacts the negative electrode active material 202 . Furthermore, as shown in FIG. 11, the poison agent 10 of the present invention may also be disposed on the surface of the negative electrode active material 202. Of course, the poison agent 10 of the present invention may also be mixed in an electrolyte.

[0053] See Figure 12. When the lithium secondary battery uses an aluminum-plastic film 51 as a packaging component, a receiving recess 52 may be formed in the press seam on the inner surface of the aluminum-plastic film 51 to accommodate the lithium secondary battery deactivator 10. In addition, the receiving recess 52 is further provided with a groove 53 for communicating with the electrochemical reaction system 50 of the lithium secondary battery. If the receiving recess 52 can maintain isolation from the electrolyte at a temperature lower than the temperature before the poison is activated, the material of the iodine molecular release agent of the poison contained in the receiving recess 52 may be the same as the material of the release agent arranged on the outside of the lithium secondary battery, and may not be affected by whether the electrolyte has a polar component or not. However, if the receiving recess cannot maintain isolation from the electrolyte at temperatures lower than the temperature before the poisoning agent is activated, the material of the molecular iodine releasing agent contained in the receiving recess 52 will be affected by whether the electrolyte has a polar component.

[0054] Similarly, when the lithium secondary battery uses a metal shell 54 as a packaging component, the metal shell 54 may be formed with a receiving recess 52 and a groove 53 for communicating the receiving recess 52 with the electrochemical reaction system 50. As shown in FIG. 13, the receiving recess 52 is used to contain the poison 10 . In this embodiment, as described above, the material of the molecular iodine releasing agent contained in the receiving recess 52 is affected by whether the receiving recess can maintain isolation from the electrolyte at temperatures below the temperature before the poisoning agent is activated.

[0055] In addition, when the poison agent is an iodine-oxygen derivative as a molecular iodine donor, and the poison agent has a first reaction trigger or is together with a second reaction trigger, these components may be arranged at different positions in the electrochemical reaction system. For example, one component is mixed with the negative electrode active material, mixed with oxide particles as the main component of the separator, or coated on the surface of the negative electrode. The reaction trigger is distributed in the electrolyte. The material of the oxide particles of the separator may be selected from solid electrolytes capable of transporting lithium ions, such as LATP, LAGP, LLZO, and LiAlSiO4, or oxides that are passive in terms of their ability to transport lithium ions, such as aluminum oxide.

[0056] As shown in FIG. 14, the poison agent 10 of the present invention may also be granulated and attached to the surface of the negative electrode active material particles 56 by an adhesive to form a spherical structure. The adhesive may be selected from polyacrylic acid (PAA), polyimide, polyamide-imide (PAI), polyvinylidene difluoride (PVDF), polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP), polyurethane (PU), polytetrafluoroethylene (PTFE), or a mixture of two or more of these materials.

[0057] Therefore, the present invention provides a lithium secondary battery capable of self-poisoning (adding a poisoning agent capable of releasing iodine molecules into the lithium secondary battery). Furthermore, the selection and configuration of materials is made according to the requirements for setting the first predetermined temperature, the second predetermined temperature, or even the third predetermined temperature. The lithium secondary battery can activate the poison at its own temperature, and the iodine molecules react with the highly active lithium atoms to form stable lithium compounds or lithium ions, rendering the lithium secondary battery inoperable, achieving self-poisoning and effectively suppressing thermal runaway.

[0058] The above descriptions are merely preferred embodiments of the present invention and are not intended to limit the scope of the claims. Therefore, any equivalent variations or modifications made in accordance with the features and spirit of the present invention should be included in the scope of the following claims. [Explanation of symbols]

[0059] 10 Poison 12 Etching direction limiter 13 Fillers 20. Lithium secondary battery 201 Current collector 202 Negative electrode active material 203 Auxiliary cutting groove 204 Cathode active material 205 Current collector 206 Separator 207 Glue Frame 208 Through Hole 209 Recess 44 Electrolytes 45 Shared current collector 50 Electrochemical reaction system 51 Aluminum-plastic film 52 Receiving recess 53 Groove 54 Metal Shell 56 Negative electrode active material particles

Claims

1. a positive electrode active material; a negative electrode active material containing lithium atoms; an electrolyte located between the positive electrode active material and the negative electrode active material, allowing lithium ions to move between the positive electrode active material and the negative electrode active material; a poison containing an iodine molecule donor that releases iodine molecules to the negative electrode active material; A lithium secondary battery capable of self-poisoning, comprising: When the temperature of the lithium secondary battery reaches a first predetermined temperature, the iodine molecules react with the negative electrode active material to form a stable lithium compound or lithium ions, and the first predetermined temperature is 100°C or higher. A lithium secondary battery capable of self-poisoning.

2. 2. The lithium secondary battery capable of self-poisoning according to claim 1, wherein the iodine molecule donor is pure iodine, a porous adsorption material to which pure iodine is adsorbed, an iodide, or an iodine-oxygen derivative, and the electrolyte is an inorganic all-solid-state electrolyte.

3. 3. The lithium secondary battery capable of self-poisoning according to claim 2, wherein the molecular iodine donor is selected from manganese iodide, copper iodide, cuprous iodide, magnesium iodide, calcium iodide, ammonium iodide, aluminum iodide, hydrogen iodide, or a mixture of two or more of the above materials.

4. 2. The lithium secondary battery capable of self-poisoning according to claim 1, wherein the iodine molecule donor is an iodine-oxygen derivative or iodide that does not melt at 80° C. or less, and the electrolyte has a polar solvent or a polar functional group.

5. 5. The lithium secondary battery capable of self-poisoning according to claim 4, wherein the electrolyte is selected from a gel electrolyte having a polar solvent, a jelly electrolyte having a polar solvent, a solid electrolyte having a polar functional group, or a mixture of at least two of the above materials.

6. The lithium secondary battery capable of self-poisoning according to claim 5 , wherein the electrolyte is further mixed with inorganic solid electrolyte particles.

7. When the iodine molecule donor is an iodine-oxygen derivative, the iodine-oxygen derivative is iodic acid (HIO ３ ), periodic acid (HIO ４ ), iodine oxide (XOI), iodate (XIO ３ ), periodate (XIO ４ ), iodate hydride (XmHn(IO ３ ) ２ ), periodate hydride (XmHn(IO ６ )), or a compound having a mixture of two or more of said materials, and X is a metal, m≧1, n≧1.

8. 5. The lithium secondary battery capable of self-poisoning according to claim 2 or 4, wherein when the iodine molecule donor is an iodine-oxygen derivative, the poisoning agent further comprises a first reaction trigger, the first reaction trigger being selected from a compound capable of providing a sulfur-oxygen bond having a free radical, a compound capable of forming lithium bis(fluorosulfonyl)imide, a benzoic acid or a phthalic acid isomer, a compound capable of forming a hydrohalic acid, a compound capable of forming boron trifluoride, or a mixture of two or more of the above materials.

9. 9. The lithium secondary battery capable of self-poisoning according to claim 8, wherein the first reaction trigger is a compound capable of providing a sulfur-oxygen bond having a free radical, and the lithium secondary battery deactivator further includes a second reaction trigger selected from a boron fluoride compound, an aluminum halide compound, or a hydrogen halide compound.

10. 5. The lithium secondary battery capable of self-poisoning according to claim 4, wherein when the electrolyte has the polar solvent or the polar functional group, the lithium secondary battery further includes a separator, the separator is disposed between the positive electrode and the negative electrode and allows the electrolyte to pass through, the separator is a ceramic separator mainly made of oxide powder, and the oxide is an oxide solid electrolyte capable of transferring lithium ions or an oxide that does not allow lithium ions to transfer.

11. 2. The self-poisoning lithium secondary battery according to claim 1, wherein the first predetermined temperature is 120[deg.] C. or higher.

12. The lithium secondary battery capable of self-poisoning according to claim 1 , wherein the poison is in a granular form.

13. 2. The lithium secondary battery capable of self-poisoning according to claim 1, wherein a free end of the positive electrode active material is disposed with a positive electrode current collector, and a free end of the negative electrode active material is disposed with a negative electrode current collector.

14. The lithium secondary battery capable of self-poisoning according to claim 13, wherein the poison is arranged on a free end surface of the negative electrode current collector, and the positive electrode current collector and the negative electrode current collector provide packaging elements for the lithium secondary battery.

15. The lithium secondary battery capable of self-poisoning according to claim 14 , wherein the free end surface of the negative electrode current collector has a plurality of auxiliary cutting grooves.

16. 15. The lithium secondary battery capable of self-poisoning according to claim 14, wherein an etching direction limiter surrounds the poisoning agent, and the etching direction limiter is inert to iodine molecules.

17. 15. The lithium secondary battery capable of self-poisoning according to claim 14, wherein the negative electrode current collector includes a plurality of through-holes, and the through-holes are filled with a hot melt material (TPM) or a thermal decomposition material.

18. 15. The lithium secondary battery capable of self-poisoning according to claim 14, wherein the negative electrode current collector includes at least one recess on the free end surface for accommodating the molecular iodine donor.

19. 2. The lithium secondary battery capable of self-poisoning according to claim 1, further comprising an aluminum-plastic film, the aluminum-plastic film being used as a packaging component of the lithium secondary battery, and an inner surface of the aluminum-plastic film in contact with the electrolyte having a receiving recess for accommodating the poison.

20. 2. The lithium secondary battery capable of self-poisoning according to claim 1, further comprising a metal packing case used as a packaging component of the lithium secondary battery, the metal packing case having a receiving recess for accommodating the poison.

21. 2. The lithium secondary battery capable of self-poisoning according to claim 1, wherein the poison is in a granular form and is attached to the surface of the particles of the negative electrode active material by an adhesive, and the adhesive is selected from polyacrylic acid, polyimide, polyamideimide, polyvinylidene fluoride, polyvinylidene fluoride-co-hexafluoropropylene, polyurethane, polytetrafluoroethylene, or a mixture of two or more of the above materials.

22. 2. The lithium secondary battery capable of self-poisoning according to claim 1, wherein the negative electrode active material is lithium metal or a material capable of forming an alloy with lithium.

23. 23. The lithium secondary battery capable of self-poisoning according to claim 22, wherein the negative electrode active material is composed of stacked silicon particles and carbon particles.

24. 24. The lithium secondary battery capable of self-poisoning according to claim 23, wherein the negative electrode active material is a mixture of a crystalline state and an amorphous state, the amount of the negative electrode active material in the amorphous state is 10% or more of the total volume, and the particle diameters of the silicon particles and the carbon particles are 1 nm to 10 nm.

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