Lithium secondary battery capable of self-poisoning

Abstract

The invention relates to a lithium secondary battery capable of self-poisoning. The lithium secondary battery comprises a positive electrode active material; a negative electrode active material; the electrolyte is positioned between the positive electrode active material and the negative electrode active material, so that lithium ions move between the positive electrode active material and the negative electrode active material; the poisoning agent is arranged in the lithium secondary battery and comprises a reaction starting catalyst and a doping agent, and the doping agent has a phosphorus-oxygen bond, a boron-oxygen bond or a sulfur-oxygen bond which is exposed at the free end or has a phosphorus-oxygen bond, a boron-oxygen bond or a sulfur-oxygen bond which is not exposed at the free end and is shielded by an organic or inorganic group; and when the temperature of the lithium secondary battery is raised to a first preset temperature, the dyeing agent reacts with the reaction initial catalyst and releases at least one phosphorus-oxygen bond, boron-oxygen bond or sulfur-oxygen bond with free radicals or unsaturated bonds, so that the positive active material of the lithium secondary battery is polluted, and the lithium secondary battery is harmless.

Description

Self-poisoning lithium secondary battery

Technical field

[0001] The present invention relates to a lithium secondary battery, in particular to a self-poisoning lithium secondary battery. [Background Technology]

[0002] Lithium-ion batteries are widely used in a variety of products, including transportation vehicles, wearable devices for consumer and industrial applications, portable devices, and energy storage devices, reaching nearly every aspect of daily life. However, lithium-ion battery accidents are common, such as fires and explosions involving mobile phone batteries and electric vehicles. This is due to the lack of comprehensive and effective solutions to lithium-ion battery safety issues.

[0003] The primary factor causing safety hazards such as fires and explosions in lithium-ion batteries is thermal runaway, primarily due to heat, specifically the exothermic reaction that causes the gradual thermal decomposition of various substances within the battery, such as the solid electrolyte interface (SEI), electrolyte, binder, and positive and negative electrode active materials. Current approaches to suppressing thermal runaway can be categorized as either external or internal to the lithium-ion battery, depending on where the safety mechanism occurs. External monitoring systems primarily utilize digital simulation, while internal monitoring systems can be categorized as either physical or chemical. Digital monitoring systems external to the lithium-ion battery utilize various technologies, such as dedicated protection circuits and management systems, to enhance safety monitoring during battery operation. Physical approaches within the lithium-ion battery include thermal shutdown separators, which seal the pores of the separator when the battery core heats abnormally, preventing ion flow. Chemical approaches within the lithium-ion battery can be categorized as either controlled or electrochemical. Examples of controlled thermal runaway include adding flame retardants to the electrolyte to control the degree of thermal runaway. Examples of electrochemical reaction mechanisms include the following: 1. Adding monomers or oligomers to the electrolyte will cause polymerization when the temperature rises, reducing the rate of ion migration, causing the ionic conductivity to decrease with temperature, and slowing the electrochemical reaction rate within the lithium secondary battery. 2. Inserting a positive temperature coefficient thermistor (PTC) material between the positive or negative electrode layer and the adjacent collector layer. When the temperature of the lithium secondary battery rises, the electronic insulation capability is enhanced, which deteriorates the electron transfer capability between the positive or negative electrode layer and the adjacent collector layer, slowing the electrochemical reaction rate. 3. Forming a modified layer on the surface of the positive electrode active material. At high temperatures, the modified layer transforms into a dense film, increasing the resistance to charge transfer and slowing the electrochemical reaction rate.

[0004] However, the above methods only passively block or inhibit the electrochemical electron or ion conduction pathway, and do not inhibit the thermal runaway by the fundamental entity driving the thermal runaway.

[0005] In view of this, the present invention proposes a self-poisoning lithium secondary battery, which solves the thermal runaway problem of the lithium secondary battery by starting from the positive electrode active material.

[0006] [Summary of the invention]

[0007] The main purpose of the present invention is to provide a self-poisoning lithium-ion battery. The self-poisoning agent is activated before the lithium-ion battery reaches a state of charge (SOC) of not less than 50% and the temperature of the lithium-ion battery approaches the critical temperature at which it undergoes self-increased temperature increase, thereby releasing phosphorus-oxygen bonds, boron-oxygen bonds, or sulfur-oxygen bonds having free radicals or unsaturated bonds to contaminate the positive electrode active material of the lithium-ion battery, thereby reducing the state of charge (SOC) of the lithium-ion battery to no more than 10%, thereby rendering the battery harmless.

[0008] To achieve the above objectives, the present invention provides a self-poisoning lithium secondary battery, comprising a positive electrode active material; a negative electrode active material; an electrolyte located between the positive electrode active material and the negative electrode active material to allow lithium ions to move between the positive electrode active material and the negative electrode active material; and a poisoning agent disposed within the lithium secondary battery, which is activated when the lithium secondary battery is heated to a first predetermined temperature, and the lithium secondary battery has a charge of not less than 50% at the first predetermined temperature. The poisoning agent comprises a reaction initiation catalyst and a dopant, wherein the dopant has a phosphorus-oxygen bond, a boron-oxygen bond, or a sulfur-oxygen bond exposed at a free end, or has a phosphorus-oxygen bond, a boron-oxygen bond, or a sulfur-oxygen bond that is not exposed at the free end and is shielded by an organic group or an inorganic group. At the first predetermined temperature, the dopant is triggered by the reaction initiation catalyst to release a phosphorus-oxygen bond, a boron-oxygen bond, or a sulfur-oxygen bond having a free radical or an unsaturated bond, thereby contaminating the positive electrode active material and rendering the lithium secondary battery harmless.

[0009] The following is a detailed description with reference to specific embodiments to facilitate understanding of the objectives, technical content, features and effects achieved by the present invention.

Brief Description of the Drawings

[0010] FIG1 is a flow chart of the self-poisoning steps of the self-poisoning lithium secondary battery of the present invention. [Specific implementation method]

[0011] To facilitate a clear understanding of the advantages, spirit, and features of the present invention, the following detailed description and discussion will be provided using examples. It should be noted that these examples are merely representative of the present invention and are not intended to limit the scope and implementation of the present invention to these examples. These examples are provided solely to make the disclosure of the present invention more thorough and easier to understand.

[0012] The terms used in the various embodiments disclosed in the present invention are only used to describe the purpose of specific embodiments and are not intended to limit the various embodiments disclosed in the present invention. Unless otherwise clearly indicated, the singular form used also includes the plural form. Unless otherwise specified, all terms used in this specification (including technical terms and scientific terms) have the same meaning as those generally understood by those skilled in the art to which the various embodiments disclosed in the present invention belong. The above-mentioned terms (such as those defined in generally used dictionaries) will be interpreted as having the same meaning as the contextual meaning in the same technical field, and will not be interpreted as having an idealized meaning or an overly formal meaning, unless clearly defined in the various embodiments disclosed in the present invention.

[0013] Throughout this specification, references to terms such as "embodiment" or "specific embodiment" indicate that the specific features, structures, materials, or characteristics described in connection with that embodiment are included in at least one embodiment of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments.

[0014] The present invention relates to a self-poisoning lithium secondary battery, which mainly includes a positive electrode active material, a negative electrode active material, an electrolyte disposed between the positive electrode active material and the negative electrode active material, and a poisoning agent disposed in the lithium secondary battery. The material of the positive electrode active material can be a positive electrode material having lithium cobalt nickel manganese oxide, for example, NCM811. The matrix material of the negative electrode active material can be lithium metal, a material that can form an alloy with lithium, such as silicon, or a material that can allow lithium to be inserted and removed, such as graphite. The electrolyte located between the positive electrode active material and the negative electrode active material allows lithium ions to move between the positive electrode active material and the negative electrode active material. The poisoning agent disposed in the lithium secondary battery is activated by temperature when the lithium secondary battery is heated to a first preset temperature, and at this time, the state of charge (SOC) of the lithium secondary battery is not less than 50%.

[0015] The poisoning agent includes a reaction initiator catalyst and a dopant. The dopant can have a phosphorus-oxygen, boron-oxygen, or sulfur-oxygen bond at the free end, and these bonds are bound to a stable first group R1, that is, a structure of Ax1Oy2-R1, where x1≧1, y1≧1, and A is selected from phosphorus, boron, or sulfur. The stabilizing component mentioned above means that the first group R1 is more stable in the electrolyte than the phosphorus-oxygen, boron-oxygen, or sulfur-oxygen bond, for example, due to a higher molecular weight. The dopant can also have a phosphorus-oxygen, boron-oxygen, or sulfur-oxygen bond that is not exposed at the free end and is shielded by an organic or inorganic group, such as R2-Ax2Oy2-R3, where x2≧1, y2≧1, and A is selected from phosphorus, boron, or sulfur. R2 and R3 can be organic or inorganic.

[0016] The reaction initiation catalyst triggers the dopant or reacts with the dopant at a first preset temperature, causing the dopant to release at least one free radical or unsaturated phosphorus-oxygen bond, boron-oxygen bond, or sulfur-oxygen bond. These free radical or unsaturated phosphorus-oxygen, boron-oxygen, or sulfur-oxygen bonds can contaminate the positive electrode active material of the lithium secondary battery, reducing the charge of the lithium secondary battery from an original level of not less than 50% to less than 10%, rendering the lithium secondary battery harmless and effectively suppressing thermal runaway of the lithium secondary battery. The first preset temperature is close to or less than the critical temperature at which the lithium secondary battery experiences self-induced hyperthermia (i.e., the thermal runaway initiation temperature). For example, the first preset temperature is not less than 100°C, and preferably not less than 120°C. The electrolyte can be an inorganic solid electrolyte, an organic solid electrolyte, a liquid electrolyte, a gel electrolyte, a jelly electrolyte, or a solid-liquid mixed electrolyte.

[0017] The contamination described here refers to the reaction of phosphorus-oxygen bonds, boron-oxygen bonds or sulfur-oxygen bonds with free radicals or unsaturated bonds with the components of the positive electrode active material. The reaction may be to produce new bonds, such as bonding with the surface of the positive electrode active material to form a passivation layer, or the reaction may be to fill the lithium-deficient vacancies in the lattice of the positive electrode active material, so that the positive electrode active material after filling the vacancies has higher lattice stability and / or lower oxygen release capacity than the lithium-deficient positive electrode active material, so as to effectively suppress thermal runaway of the lithium secondary battery and reduce the charge of the lithium secondary battery to below 10%, thereby achieving the so-called harmlessness.

[0018] Based on the above, the self-poisoning lithium secondary battery of the present invention includes the following steps during the self-poisoning process: First, as in step S1, a lithium secondary battery is provided, which contains a poisoning agent, the poisoning agent comprising the reaction initiating catalyst and the dopant, and the lithium secondary battery is in a state capable of normal charge and discharge operation. Then, as described in step S2, when the lithium secondary battery abnormally heats up to a first predetermined temperature, the reaction initiating catalyst triggers the dopant to release a boron-oxygen bond, a phosphorus-oxygen bond, or a sulfur-oxygen bond containing a free radical or unsaturated bond, thereby poisoning or contaminating the positive electrode active material of the lithium secondary battery, rendering the lithium secondary battery inoperable. The abnormal temperature rise of the lithium secondary battery may be caused by an internal short circuit during charge and discharge, or by discharge caused by foreign matter puncturing the battery. Furthermore, to distinguish the lithium secondary battery of the present invention from lithium secondary batteries that have lost their charge efficiency and are therefore considered discarded or ineffective, the lithium secondary battery of the present invention is further defined by a state of charge (SOC) to determine whether the state of charge of the lithium secondary battery of the present invention is at least 50% when the self-poisoning process is triggered.

[0019] The above-mentioned reaction starting catalyst can be a compound containing hydrohalic acid, for example, a first salt containing fluorine, and the electrolyte is saturated with at least one second salt. The second salt is used to provide lithium ions for the charge and discharge operation of the lithium secondary battery, so the first salt is in a non-dissolved state in the electrolyte. In addition, the first salt and the second salt can be different. The first salt can be, for example, lithium hexafluorophosphate (LiPF6), but because it has hexafluorophosphate ions (PF6 - ) compounds are relatively unstable and easily form lower hydrocarbons such as alkanes or alkenes. Therefore, the first fluorine-containing salt can be selected from potassium tetrafluoroborate (KBF4), sodium tetrafluoroborate (NaBF4), lithium bismuth tetrafluoroate (LiBiF4), lithium hexafluoroborate (LiBF6), lithium hexafluoroarsenic (LiAsF6) or lithium heptafluorosulfur (LiSF7). ， Or compared to lithium (Li) or ammonium (NH4) can make hexafluorophosphate (PF6 - ) More stable materials such as potassium hexafluoroborate (KPF6) or sodium hexafluoroborate (NaPF6).

[0020] Another form of a dopant has the chemical formula Ax3By3Cz3, where A is selected from lithium, sodium, potassium, or ammonium (NH4), and By3Cz3 is selected from a phosphorus-fluorine bond or a boron-fluorine bond, and x3≧1, y3≧1, and z3≧1. For example, the dopant is lithium boron tetrafluoride (LiBF4), sodium boron tetrafluoride (NaBF4), potassium boron tetrafluoride (KBF4), lithium boron hexafluoride (LiBF6), lithium arsenic hexafluoride (LiAsF6), lithium sulfur heptafluoride (LiSF7), or a mixture of these materials.

[0021] For example, when the reaction starting catalyst is lithium hexafluorophosphate and the doping agent is lithium boron tetrafluoride, the following reactions 1-5 will occur to generate boron-oxygen bonds with free radicals or unsaturated bonds to contaminate the positive electrode: LiPF6→LiF+PF5....(1) PF5+H2O→POF3+HF....(2) LiBF4+HF→BF3+LiF....(3) BF3+3H2O→3HF+H3BO3....(4)

[0022] The water in the above reaction may come from trace water in the lithium secondary battery, or may be formed by the reaction of hydrofluoric acid (HF) with the positive electrode active material, the negative electrode active material, or the carbonate organic solvent contained in the electrochemical reaction system. For example, the carbonate organic solvent may be ethylene carbonate (EC) or propylene carbonate (PC). In addition, when the lithium secondary battery has a ceramic separator, the water in the above reaction may also come from the water produced by the reaction of hydrofluoric acid with the ceramic separator. The main material of the ceramic separator may be an oxide material as the main structure, and this oxide material may be a good conductor of lithium ions, such as a solid electrolyte, or a conductor of non-lithium ions. When the oxide is a solid electrolyte that can transfer lithium ions, it may be LATP, LAGP, LLZO or LiAlSiO4. When the oxide is an oxide that is passive in its ability to transfer lithium ions, it may be aluminum oxide. For example, when the oxide is aluminum oxide, it will release water after being attacked by hydrofluoric acid, as shown in the following reaction formula 6. Ai2O3+6HF→2AIF3+3H2O.....(6)

[0023] As previously described, when the dopant releases a sulfoxyl bond with a free radical or unsaturated bond, and the sulfoxyl bond is located at the free end of the dopant, the dopant may be sodium trifluoromethanesulfinate (CF3SO2Na), perfluorobutylsulfonic acid (C4F9SO3H), sodium perfluorobutylsulfonate (C4F9SO3Na), or potassium perfluorobutylsulfonate (C4F9SO3K). Furthermore, when the sulfoxyl bond is bonded to a first group R1, the first group R1 may be a compound composed of a carbon chain of at least one carbon atom, thereby ensuring the dopant's stability in the electrochemical reaction system before reaching a first predetermined temperature. Before reaching the first predetermined temperature, the reaction initiation catalyst is chemically inert in the lithium secondary battery. Upon reaching the first predetermined temperature, the reaction initiation catalyst is released, cleaving the sulfoxyl bond with the first group R1, forming a sulfoxyl bond with a free radical or unsaturated bond. The first group R1 may be an alkyl group, an ether group, an aryl group, an aralkyl group, or an alkaryl group. The structure of the first group R1 can determine whether the dopant is insoluble or soluble in different solvents. Soluble here means that the dopant can be dissolved in solvents for liquid electrolytes, colloidal electrolytes, or gel electrolytes (e.g., propylene carbonate (PC)), or in plasticizers for solid polymer electrolytes. When the dopant is added to a lithium secondary battery, the amount of the dopant dissolved in these solvents or plasticizers is at least 1% by weight of the solvent or plasticizer.

[0024] The reaction initiator catalyst of the lithium secondary battery of the present invention may also be selected from boron fluoride or aluminum halide. The boron fluoride may be potassium fluoroborate (KBF4), sodium fluoroborate (NaBF4), or ammonium fluoroborate (NH4BF4), and the aluminum halide may be aluminum chloride (AlCl3) or aluminum bromide (AlBr3).

[0025] When the sulfur-oxygen bond with a free radical or an unsaturated bond is located at the side end of the dopant, although it already has the ability to contaminate the positive electrode active material, because the first group R1 is a molecular form with a relatively stable structure, the presence of the first group can reduce the degree of contamination of the positive electrode active material by the sulfur-oxygen bond before the first preset reaction temperature is reached. However, this also means that the real-time suppression effect of the dopant with such a sulfur-oxygen bond on the lithium secondary battery when thermal runaway is about to occur will be reduced. To this end, in this application, a reaction initiation catalyst with a bond-breaking effect is also used to break the bond between the first group R1 and the sulfur-oxygen bond at the first preset temperature, so that the first group R1 is separated from the sulfur-oxygen bond, and the sulfur oxide has a stronger migration ability, so as to increase the effect of contaminating the positive electrode active material, reduce the reversibility / activity of the positive electrode active material, and thus suppress the thermal runaway of the lithium secondary battery.

[0026] In the present invention, the sulfur-oxygen bond of the dopant can also be selected from a shielded state, that is, a state not exposed at the free end, such as LiFSi (lithium bis(fluorosulfonyl)imide) or sodium salt F-(SO2)-N - -(SO2)-FM + , M represents lithium or sodium, 3-phenylsulfonylbenzenesulfonic acid, peroxydisulfuric acid, potassium peroxydisulfate, sodium peroxydisulfate. These shielded or non-free end forms are used to avoid or reduce the release of dopants during the normal charge and discharge operation of lithium secondary batteries or in the relevant manufacturing process after being mixed in lithium secondary batteries, which affects the utilization rate of lithium secondary batteries. In this embodiment, the dopant is a sulfur-oxygen bond with a second group R2 and a third group R3 bonded to both ends, and R2 and R3 are the same or different organic or inorganic groups. The dopant is essentially chemically inert in the lithium secondary battery until the reaction initiation catalyst attacks the dopant to cut off the bond between R2 and / or R3 and the sulfur-oxygen bond, so that the sulfur-oxygen bond has a free radical or an unsaturated bond, and then it begins to contaminate the positive electrode active material. For example, when the dopant is a structure in which the sulfur-oxygen bond is not exposed at the free end, the structure of these dopants can be, for example, sulfinic acid group or sulfonyl Wherein R2 and R3 are organic groups or inorganic groups.

[0027] Furthermore, the structure of the above-mentioned sulfur-oxygen bond can be or For example, having The structural doping agent may be sodium octyl sulfate, hexyl sulfate, sodium salt, sodium ethyl sulfate, sodium 1-octanesulfonate monohydrate, 1-octanesulfonic acid sodium salt, sodium 1-heptanesulfonate, sodium hexanesulfonate, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, sodium 2-ethylhexyl sulfate, sodium ethyl sulfate, potassium nonafluoro-1-butanesulfonate, trifluoromethanesulfonyl chloride, or sodium 1-heptanesulfonate. chloride), 4-(3-butyl-1-imidazolio)-1-butanesulfonate, 3-(1-Pyridinio)-1-propanesulfonate, Dimethyl-2-hydroxyethylammoniumpropane sulfonate, 3-(Decyldimethylammonio)-propane-sulfonate inner salt, [2-(Methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide, 1-Ethyl-3-methylimidazolium ethyl sulfate sulfate), copper(I)trifluoromethanesulfonate benzene complexcomplex), 1-Ethyl-3-methylimidazolium trifluoromethanesulfonate, 1-Fluoropyridinium triflate, 4-Formyl-1-methylpyridinium benzenesulfonate, 3-Hydroxynaphthalene-2,7-disulfonic acid disodium salt, Potassium benzene-1,2-disulfonate, Lithium trifluoromethanesulfonate, Potassium trifluoromethanesulfonate, Sodium bisulfite solution, Sodium metabisulfite, Sodium thiosulfate thiosulfate), sodium 1-butanesulfonate, potassium diphenylsulfone sulfonate, heptadecafluorooctanesulfonic acid potassium salt, or a mixture of at least two of the above materials.

[0028] For example, having The first compound of the structure can 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 at least two of the above materials.

[0029] For example, having The first compound of the structure 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. 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 at least two of the above materials.

[0030] Compounds having a phosphorus-oxygen bond and useful as dopants include copper (II) pyrophosphate hydrate, aluminum phosphate, calcium phosphate dibasic, sodium phosphate dibasic, sodium phosphate monobasic, sodium phosphate, potassium phosphate monobasic, potassium phosphate tribasic, potassium phosphate dibasic, sodium pyrophosphate tetrabasic, iron (III) pyrophosphate, sodium tripolyphosphate, potassium pyrophosphate, 1,10-decyldiphosphonic acid (1,10-Decyldiphosphonic acid), (12-Phosphonododecyl)phosphonic acid, Dibutyl phosphite, Dimethyl phosphite, Diethyl phosphite, Bis(2-ethylhexyl)phosphate, Dibenzyl phosphite, Triethyl phosphite, Di-tert-butyl phosphite, Triethyl phosphate, Diethyl allyl phosphate, Diethyl allylphosphonate, Diethyl vinylphosphonate, Dimethyl vinylphosphonate, Diallyl phosphite PHOSPHITE), diethyl benzylphosphonate, diethylenetriaminepentakis(methylphosphonic acid), diethyl ethylphosphonate, diethyl isocyanomethylphosphonate, diethyl(methylthiomethyl)phosphonate, diethyl(difluoromethyl)phosphonate, tris(2,2,2-trifluoroethyl)phosphite, diethyl methylphosphonate, Eaton's Reagent, or a mixture of at least two of the above materials.

[0031] Compounds having a boron-oxygen bond and useful as dopants include 2-Acetylaminophenylboronic acid pinacol ester, 3-Acetyl-2-fluorophenylboronic acid, 3-Acetylphenylboronic acid, 4-Acetylphenylboronic acid, phenylboronic acid, 4-Amino-3-nitrophenylboronic acid, 2-Aminophenylboronic acid pinacol ester, 3-Aminophenylboronic acid, 3-Aminophenylboronic acid pinacol ester, 2-Aminopyrimidine-5-boronic acid, and 2-Aminophenylboronic acid pinacol ester. acid), Bis(pinacolato)diboron, Boric acid, 4-Bromobutylboronic acid, 2-BROMO-3-ETHOXY-6-FLUOROPHENYLBORONIC, 4-Bromomethylphenylboronic acid pinacol ester, n-Butylboronic acid pinacol ester, Borax, Lithium bis(oxalato)borate, or a mixture of at least two of the above materials.

[0032] When the poisoning agent is in an insoluble form, it can be adjacent to or in direct contact with the positive electrode active material. For example, the poisoning agent can be mixed with the particles of the positive electrode active material, resulting in a random distribution between the particles. Alternatively, the poisoning agent can be coated on the surface of the positive electrode active material. The electrolyte of the lithium secondary battery containing this poisoning agent can be a solid electrolyte, a semi-solid electrolyte, a liquid electrolyte, or a mixture thereof.

[0033] When the poisoning agent is in a soluble form, the poisoning agent may be mixed into the electrolyte system. The electrolyte of this type of lithium secondary battery may be a pure liquid electrolyte, a pure gel electrolyte, a pure condensed electrolyte, or a pure solid polymer electrolyte, or a mixture thereof. In addition, the electrolyte may also be optionally mixed with an oxide solid electrolyte.

[0034] In summary, the present invention provides a self-poisoning lithium secondary battery, which contains a poisoning agent. When the lithium secondary battery has a charge of not less than 50% and is heated to a first predetermined temperature, the poisoning agent releases a phosphorus-oxygen bond, a boron-oxygen bond, or a sulfur-oxygen bond having a free radical or an unsaturated bond, thereby contaminating the positive electrode active material of the lithium secondary battery, stabilizing the positive electrode active material lattice, preventing or reducing the precipitation of oxygen atoms, and maintaining a charge of not more than 10%, thereby causing the lithium secondary battery to be poisoned and lose its charge and discharge capabilities, thereby effectively suppressing the occurrence of thermal runaway.

[0035] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Therefore, any equivalent changes or modifications based on the features and spirit of the claims of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A self-toxic lithium secondary battery comprising: Positive electrode active material; Negative electrode active material; An electrolyte, which is located between the positive electrode active material and the negative electrode active material to allow lithium ions to move between the positive electrode active material and the negative electrode active material; and A poisoning agent, which is activated when the lithium secondary battery is heated to a first preset temperature, and the charge of the lithium secondary battery is not less than 50% at the first preset temperature, and the poisoning agent comprises: a reaction starting catalyst; and A dopant having a phosphorus-oxygen bond, a boron-oxygen bond or a sulfur-oxygen bond exposed at a free end, or having a phosphorus-oxygen bond, a boron-oxygen bond or a sulfur-oxygen bond not exposed at a free end and shielded by an organic group or an inorganic group, wherein at the first preset temperature, the dopant reacts with the reaction starting catalyst and releases at least one boron-oxygen bond, a phosphorus-oxygen bond or a sulfur-oxygen bond having a free radical or an unsaturated bond to contaminate the positive electrode active material; The first preset temperature is not less than 100°C.

2. The self-poisonable lithium secondary battery as claimed in claim 1, wherein the reaction initiation catalyst is a boron fluoride, an aluminum halide or a hydrohalic acid compound.

3. The self-poisonable lithium-ion battery as claimed in claim 2, wherein when the reaction initiating catalyst is a borofluoride, the reaction initiating catalyst is potassium borofluoride (KBF4), sodium borofluoride (NaBF4) or ammonium borofluoride (NH4BF4), and when the reaction initiating catalyst is an aluminum halide, the reaction initiating catalyst is aluminum chloride (AlCl3) or aluminum bromide (AlBr3).

4. The self-poisonable lithium secondary battery as claimed in claim 1, wherein when the reaction initiation catalyst is a hydrohalic acid compound, the reaction initiation catalyst is a first salt containing fluorine, the electrolyte is saturated with at least a second salt, the first salt is in a non-dissolved state in the lithium secondary battery, and the first salt is different from the second salt.

5. The self-poisoning lithium secondary battery as claimed in claim 4, wherein the first salt is lithium hexafluorophosphate (LiPF6).

6. The self-poisonable lithium secondary battery as claimed in claim 1, wherein the doping agent is A x B y F z , wherein A is selected from lithium, sodium or ammonium (NH4), B y F z Selected from a phosphorus-fluorine bond or a boron-fluorine bond, wherein x≧1, y≧1, z≧1.

7. The self-poisonable lithium secondary battery as claimed in claim 6, wherein the dopant is KBF4, NaBF4, LiBF4, LiBF6, LiSF7 or a mixture of at least two of the above materials.

8. The self-poisonable lithium secondary battery as claimed in claim 1, further comprising a ceramic isolation layer, wherein the reaction initiating catalyst reacts with the ceramic isolation layer to release water. 9 . The self-poisoning lithium secondary battery as claimed in claim 8 , wherein the main material of the ceramic isolation layer is selected from oxide solid electrolytes or passive ceramic powders that cannot transfer lithium ions.

10. The self-poisonable lithium secondary battery as claimed in claim 1, wherein the reaction initiating catalyst reacts with the carbonate organic solvent of the electrolyte to release water.

11. The self-poisonable lithium secondary battery as claimed in claim 1, wherein when the doping agent has a phosphorus-oxygen bond, a boron-oxygen bond or a sulfur-oxygen bond exposed at the free end, the sulfur-oxygen bond is bonded to a first group, the first group is a carbon chain of at least one carbon atom, and the reaction initiation catalyst triggers the sulfur-oxygen bond to break the bond with the first group. 12 . The self-poisonable lithium secondary battery as claimed in claim 11 , wherein the first group is an alkyl group, an ether group, an aryl group, an aralkyl group or an alkylaryl group.

13. The self-poisonable lithium secondary battery as claimed in claim 1, wherein when the doping agent has a phosphorus oxygen bond, a boron oxygen bond or a sulfur oxygen bond which is not exposed at the free end and both ends of the phosphorus oxygen bond, the boron oxygen bond or the sulfur oxygen bond are shielded by an organic group or an inorganic group, the organic groups or inorganic groups at both ends are the same, and the reaction initiation catalyst cuts off the bond between at least any one of the organic group or inorganic group and the phosphorus oxygen bond, the boron oxygen bond or the sulfur oxygen bond, so that the phosphorus oxygen bond, the boron oxygen bond or the sulfur oxygen bond has a free radical or an unsaturated bond.

14. The self-poisonable lithium secondary battery as claimed in claim 1, wherein when the dopant has a phosphorus-oxygen bond, a boron-oxygen bond or a sulfur-oxygen bond which is not exposed at the free end and both ends are shielded by organic groups or inorganic groups, the organic groups or inorganic groups at the two ends are different, and the reaction initiation catalyst cuts off the bond between at least any one of the organic groups or inorganic groups and the phosphorus-oxygen bond, the boron-oxygen bond or the sulfur-oxygen bond, so that the phosphorus-oxygen bond, the boron-oxygen bond or the sulfur-oxygen bond has a free radical or an unsaturated bond. 15 . The self-poisoning lithium secondary battery as claimed in claim 1 , wherein the first preset temperature is above 120° C.

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