Flame-proof and explosion-proof lithium battery
By using basalt fiber cloth or fireproof insulating film as the separator in lithium batteries and combining flame-proof and explosion-proof devices, the short circuit and self-ignition problems caused by aging and deformation of lithium batteries are solved, which significantly improves the safety and stability of the battery.
Patent Information
- Application Number
- CN202421090277.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-11
- Publication Date
- 2025-05-02
- Estimated Expiration
- 2034-05-11
AI Technical Summary
After long-term use, existing lithium batteries have short circuits due to aging and deformation, causing a collision between positive and negative poles, resulting in sparks and ignition batteries. The diaphragm is flammable, plastic, and deformed, resulting in spontaneous combustion and self-destruction.
Basalt fiber cloth or fireproof insulating film is used as a diaphragm to replace the traditional polyethylene and polypropylene separators, and flame-proof and explosion-proof devices are installed inside and outside the battery, including inserting fire-proof insulating materials into the positive and negative electrode plates, setting up overheating protection devices, spraying fire-proof paint on the outside, and injecting thermal glue to improve heat dissipation effect.
It effectively avoids short circuit and self-destruction caused by aging and deformation of lithium batteries, improves the safety and stability of the battery, and prevents overall damage and burning of the battery pack.
Smart Images
Figure CN222826475U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of energy, in particular to the field of safe energy of automotive power batteries, in particular to flameproof and explosion-proof lithium batteries in new energy vehicles. Background Art
[0002] At present, lithium batteries are widely used, but the technology of lithium battery self-ignition and explosion has not been completely solved, especially high-power automotive power lithium batteries, which often self-ignite and explode. Although there are some patents for flame-proof and explosion-proof lithium batteries, they can only solve the fire prevention problem of the outside of lithium batteries, but cannot solve the essential problem of the battery igniting due to the internal aging and deformation of the lithium battery due to the collision of the positive and negative poles, resulting in a short circuit and sparks. For example: the raw materials of lithium battery separators are mostly polyethylene and polypropylene. According to their different physical and chemical properties, the two materials can be made into woven membranes, microporous membranes, composite membranes and other types of lithium battery separators. At present, these two materials are also widely used in industry. What is the role of lithium battery separators? The main function is to separate the positive and negative electrodes of the battery to prevent the two poles from contacting and short-circuiting. In addition, since the lithium battery separator has a large number of micropores, the separator can also ensure that the electrolyte ions can pass freely and is conducive to the formation of a charge and discharge circuit. In the structure of lithium batteries, in addition to positive and negative electrode materials and electrolytes, the diaphragm is also a very critical element. Usually, the performance of the diaphragm directly determines the interface structure, internal resistance, etc. of the battery, and will also directly affect the safety, capacity and cycle life of the battery. Therefore, the cost of the diaphragm is the highest besides the positive and negative electrode materials. (Please see: What materials are lithium battery diaphragms made of, what are the functions of lithium battery diaphragms, electric vehicle knowledge, invincible electric network, 2022-10-01 07:03:01). Since polyethylene and polypropylene are flammable, soft, plastic and easy to deform, and burn after ignition, they are not suitable for battery diaphragms. Lithium burns in the air, and the product of lithium burning in the air is lithium oxide, and a small amount of lithium nitride is generated at the same time. The chemical formula is: 4Li+O2=ignition=2Li2O, 6Li+N2=ignition=2Li3N. Because lithium is very active in chemical properties, it can react with oxygen in the air, burn violently and emit dazzling white light, and can also react with nitrogen to generate lithium nitride. Since lithium crystals are easily generated during the electrolysis of lithium ions in lithium batteries, they are ignited by electric sparks when the positive and negative electrodes are short-circuited, reacting with oxygen and nitrogen entering the battery, causing spontaneous combustion and explosion. Therefore, lithium batteries currently on the market have great defects. Utility Model Content
[0003] The utility model aims to provide a flameproof and explosion-proof lithium battery, which can avoid the essential defect of lithium batteries that the positive and negative poles collide to cause a short circuit due to aging and deformation of the battery due to long-term use, and generate sparks to ignite the lithium battery. It can also solve the problems of flammable, plastic and deformable plastic diaphragms in the background technology, as well as the problem of spontaneous combustion and explosion of lithium batteries due to deformation, breakage, leakage of oxygen and nitrogen, and reaction with lithium crystals.
[0004] The purpose of the utility model is achieved as follows: Basalt fiber (BasaIt Fiber, referred to as BF) is a new type of inorganic environmentally friendly high-performance material, which is generally brown in color, and some are golden. It is composed of oxides such as SiO2, Al2O3, CaO, FeO, and a small amount of impurities, and each component in the fiber has its specific properties. Basalt continuous fiber basalt fiber, as a reinforcing material, not only has good stability, excellent mechanical properties and corrosion resistance, but also has the advantages of good insulation, excellent heat insulation and sound insulation, and good wave transmission performance. Because the basalt ore itself gives basalt fiber many excellent properties, the basalt fiber itself has very high durability and excellent mechanical properties, which are very practical in both military and civilian fields. At present, the fireproof cloth woven from basalt fiber spinning has been used in the production of flame-retardant and heat-insulating protective clothing and fire blankets. The products are mainly used in fire protection, metallurgy, military industry and other industries. (See: Jung Plastics Industry, Basalt Fiber and Applications, Sohu.com 2018-01-30 12:21).
[0005] What are the main components of the electrolyte of lithium iron phosphate batteries? The materials required for the manufacture of lithium iron phosphate batteries include positive electrode materials, negative electrode materials, electrolytes and diaphragms. In terms of electrolytes, China has become the world's largest electrolyte production and market. The industry is showing explosive growth, causing the price of lithium hexafluorophosphate to fall rapidly.
[0006] Lithium iron phosphate battery refers to a lithium-ion battery that uses lithium iron phosphate as the positive electrode material. The positive electrode materials of lithium-ion batteries mainly include lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, ternary materials, lithium iron phosphate, etc. Among them, lithium cobalt oxide is the positive electrode material used by most lithium-ion batteries.
[0007] The electrolytes mainly used in lithium iron phosphate batteries on the market are lithium perfluoride, fluorinated lithium salts, lithium hexafluorophosphate, etc. Batteries made of lithium perfluoride have poor low-temperature performance and are at risk of explosion, and Japan and the United States have banned their use. Batteries made of fluorinated lithium salts have good performance, no explosion risk, and strong applicability. Batteries made of lithium hexafluorophosphate, in addition to good battery performance, no explosion risk, and strong applicability, will be relatively simple to handle waste batteries in the future, and are friendly to the ecological environment. Therefore, batteries made of lithium hexafluorophosphate have a very broad market prospect. (See: LARGE, The main components of lithium iron phosphate battery electrolyte, April 16, 2019).
[0008] Thermally conductive adhesive is a single-component, heat-conductive, room-temperature curing silicone adhesive sealant. It undergoes a condensation reaction with moisture in the air to release low molecular weight molecules, causing cross-linking and curing. It is then vulcanized into a high-performance elastomer. Good-adhesive thermally conductive adhesive has excellent resistance to hot and cold alternation, aging resistance and electrical insulation. It also has excellent moisture resistance, shock resistance, corona resistance, leakage resistance and chemical resistance. It can be used continuously at -60∽280℃ and maintain performance. It does not swell and has good adhesion to most metal and non-metal materials. Thermally conductive adhesive, also known as thermally conductive silicone. It is a silicone rubber made of organic silicone as the main body, with fillers, thermally conductive materials and other polymer materials added, and has good thermal conductivity and electrical insulation properties. It is widely used in electronic components. Also known as: thermally conductive silicone, thermally conductive silicone rubber, thermally conductive silicone, thermally conductive silicone Licon. Accelerator curing, acrylate. It is used to bond transformers, transistors and other heating components to printed circuit board assemblies or radiators. (Please see: 360 Encyclopedia, Thermal Conductive Adhesive).
[0009] Lithium dendrites, also known as lithium dendrites, are dendritic lithium metal formed when lithium ions are reduced during the charging process of lithium batteries. The growth of lithium dendrites is one of the fundamental issues affecting the safety and stability of lithium-ion batteries. The growth of lithium dendrites will lead to instability of the electrode and electrolyte interface during the cycle of lithium-ion batteries, destroying the generated solid electrolyte interface (SEI) film. During the growth process, lithium dendrites will continuously consume electrolyte and cause irreversible deposition of metallic lithium, forming dead lithium and causing low coulomb efficiency; the formation of lithium dendrites will even pierce the diaphragm and cause a short circuit inside the lithium-ion battery, causing thermal runaway of the battery and causing combustion and explosion.
[0010] The formation process of lithium dendrites can be divided into several stages: film formation stage, nucleation stage and growth stage. In the film formation stage, during the charge and discharge process of the lithium metal negative electrode, the lithium metal is highly active and reacts with the electrolyte to form a SEI film. The SEI film is a medium that isolates the electrolyte and metallic lithium, preventing the two from continuing to react. In the nucleation stage, that is, during the deposition process, lithium ions are reduced to lithium atoms, and the lithium atoms aggregate to form small crystal nuclei. Finally, uneven deposition continues on the surface of the negative electrode, forming irregular protrusions until the original SEI film is broken.
[0011] Controlling the growth of lithium dendrites is the key to improving the performance and safety of lithium batteries. Some methods to control the growth of lithium dendrites include controlling the flatness of the positive and negative current collectors after coating, making the size of the negative electrode particles smaller than the critical thermodynamic radius, adding electrolyte additives that stabilize the negative electrode-electrolyte interface, and replacing liquid electrolytes with high-strength gel / solid electrolytes. (See: Baidu Encyclopedia, Lithium Dendrites).
[0012] A flameproof and explosion-proof lithium battery, including a lithium battery and a flameproof and explosion-proof device. Flameproof and explosion-proof protection is provided inside and outside the battery, including sandwiching fireproof insulating materials between the positive and negative plates of the battery, providing an overheating protection device between the positive and negative poles, and spraying fireproof paint on the outside. That is: after sandwiching basalt fiber cloth or fireproof insulating film between the positive and negative plates, put it into a flameproof and explosion-proof cup, inject thermal conductive glue, spray fireproof paint on the surface, and seal it with basalt fiber cloth. One end of the bimetallic strip is connected to the negative plate, and the other end is connected to the negative electrode wire. Specifically:
[0013] Insert basalt fiber cloth or fireproof insulating film between the positive and negative plates, connect the positive and negative electrodes respectively, roll them into a cylinder, put them into a cylindrical electrolytic cell in a rectangular flame-proof and explosion-proof cup, and then inject electrolyte; inject thermal conductive glue into the cavity between the inner surface of the flame-proof and explosion-proof cup and the electrolytic cell, seal it with basalt fiber cloth, connect one end of the bimetallic strip to the negative plate and the other end to the negative electrode wire, and evenly apply thermal conductive glue on the seal; spray fire retardant paint on the surface of the flame-proof and explosion-proof cup.
[0014] The insulating, fireproof, flame-retardant and hardness of fireproof insulating materials such as basalt fiber cloth or fireproof insulating film can be used to separate the positive and negative plates from colliding and short-circuiting due to aging and deformation; and because basalt fiber cloth or fireproof insulating film has micropores, it can penetrate the electrolyte and does not affect the electrolysis between the positive and negative electrodes. At the same time, due to the characteristics of thermal expansion and contraction, the bimetallic strip bends at high temperatures and cuts off the circuit, thereby playing the role of automatic overheating protection, which is better than PCT thermistors, and there is no situation of breakdown or burning, and it will not damage other batteries in the battery pack. Sealing with basalt fiber cloth and applying thermal conductive glue not only plays a role of fireproof and flame-retardant insulation, but also facilitates heat dissipation, and at the same time facilitates the discharge of gases generated during electrolysis, so that the battery will not foam due to heat and the diaphragm will not deform due to long-term charging and discharging. Thermally conductive glue is injected into the gap between the inner surface of the flame-proof and explosion-proof cup and the electrolytic cell to prevent fire and heat transfer and dissipate heat. The flame-proof and explosion-proof cup prevents the electrolytic cell from deformation and damage, and is sprayed with fire-retardant paint on the surface to separate the batteries from transferring heat to each other and causing overall damage to the battery pack. At the same time, it decomposes into non-flammable inert gases when heated to block oxygen and nitrogen from entering the battery. At the same time, it prevents the decomposed lithium crystals from coming into contact with oxygen and nitrogen during the electrolysis of the lithium battery to react and cause spontaneous combustion and explosion accidents, thereby better preventing flames and explosions.
[0015] Due to the above-mentioned technical solutions of using the insulation, fireproof, flame retardant, hardness of fireproof insulating materials such as basalt fiber cloth or fireproof insulating film, heat dissipation of thermal conductive glue, automatic cut-off protection of bimetallic strip overheating, and oxygen isolation of fireproof paint, the diaphragm mainly composed of polyethylene and polypropylene in the lithium battery is replaced by basalt fiber cloth or fireproof insulating film, which is fireproof and flame retardant, the bimetallic strip overheats and automatically cuts off the circuit, the heat conductive glue dissipates heat, and the fireproof paint is insulated, oxygen-isolated, nitrogen-isolated, and flame-retardant, so that the lithium battery will not spontaneously combust or explode, and will not cause damage or burning of the battery pack as a whole. Therefore, the utility model is safer and more effective than the background technology. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The following is a brief description of the reference numerals in the comparative embodiment.
[0017] Figure 1 Schematic diagram of inserting basalt fiber cloth or fireproof insulation film between the positive and negative plates
[0018] Figure 2 Schematic diagram of basalt fiber cloth or fireproof insulation film sandwiched between the positive and negative plates and rolled into a cylindrical shape
[0019] Figure 3 , Schematic diagram of basalt fiber cloth sealing
[0020] Figure 4 Schematic diagram of the electrolytic cell in the rectangular flameproof and explosion-proof cup
[0021] Figure 5 Schematic diagram of sandwiching basalt fiber cloth or fireproof insulation film between the positive and negative plates and rolling them into a cylindrical shape and loading them into the electrolytic cell
[0022] Figure 6 Schematic diagram of sealing with basalt fiber cloth after injecting electrolyte
[0023] Figure 7 Schematic diagram of parallel battery pack after connecting positive and negative electrodes with bimetallic strips
[0024] 1. Positive plate 2. Negative plate 3. Basalt fiber cloth or fireproof insulation film 4. Basalt fiber cloth seal 5. Electrolytic cell 6. Rectangular flameproof and explosion-proof cup 7. Positive electrode 8. Negative electrode 9. Electrolyte 10. Bimetallic strip 11. Thermal conductive adhesive DETAILED DESCRIPTION
[0025] A basalt fiber cloth 3 is sandwiched between the positive plate 1 and the negative plate 2, and a positive electrode 7 of any material selected from the group consisting of lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, ternary material nickel cobalt manganese oxide, lithium iron phosphate, etc. is connected to the positive plate 7, and a negative electrode 8 of any material selected from the group consisting of general carbon materials, alloys, tin-based materials, lithium-containing transition metal nitrides, etc. is rolled into a cylindrical shape, and placed in a cylindrical aluminum electrolytic cell 5 in a rectangular flame-proof and explosion-proof cup, and then an electrolyte 9 of any one selected from the group consisting of lithium perfluoride, lithium fluoride salt, lithium hexafluorophosphate, etc. is injected, and a thermal conductive adhesive 11 is injected into the cavity between the inner surface of the rectangular flame-proof and explosion-proof cup 6 and the cylindrical aluminum electrolytic cell 5, and a basalt fiber cloth is used to seal the mouth 4, and then a bimetallic strip 10 is connected to the negative plate 2 at one end and to the negative electrode 8 wire at the other end, and then the thermal conductive adhesive is evenly applied to the sealing portion, and the surface of the rectangular flame-proof and explosion-proof cup 6 is sprayed with steel structure fire retardant paint.
[0026] A fireproof insulating film 3 made of PC, PET or the like can also be sandwiched between the positive plate 1 and the negative plate 2, and a positive electrode 7 made of any material selected from the group consisting of lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, ternary material nickel cobalt manganese oxide, lithium iron phosphate, etc., and a negative electrode 8 made of any material selected from the group consisting of general carbon materials, alloys, tin-based materials, lithium-containing transition metal nitrides, etc. can be connected to the positive plate 1 and the negative plate 7 can be rolled into a cylindrical shape and placed in a cylindrical electrolytic cell 5 in a rectangular flameproof and explosion-proof cup 6, and then an electrolyte 9 selected from the group consisting of any one of lithium perfluorate, lithium fluoride salt, lithium hexafluorophosphate, etc. can be injected; a thermal conductive adhesive 11 can be injected into the gap between the inner surface of the rectangular flameproof and explosion-proof cup 6 and the cylindrical aluminum electrolytic cell 5, and a basalt fiber cloth can be used to seal the cavity 4, and then a bimetallic strip 10 can be connected to the negative plate 2 at one end and to the negative electrode 8 wire at the other end, and then the thermal conductive adhesive can be evenly applied to the sealing portion; and a steel structure fireproof paint can be sprayed on the surface of the rectangular flameproof and explosion-proof cup 6.
[0027] The insulation, fireproof, flame retardant properties and hardness of fireproof insulating materials such as basalt fiber cloth or fireproof insulating film are used to separate the positive and negative plates from colliding and short-circuiting due to aging and deformation; and because basalt fiber cloth or fireproof insulating film has micropores, it can penetrate the electrolyte and does not affect the electrolysis between the positive and negative electrodes. At the same time, due to the characteristics of thermal expansion and contraction, the bimetallic strip bends at high temperatures and cuts off the circuit, thereby playing the role of automatic overheating protection, which is better than PCT thermistor, and there is no situation of breakdown or burning, and it will not damage other batteries in the battery pack. Use basalt fiber cloth to seal and apply thermal conductive glue, which not only plays the role of fireproof and flame retardant insulation, but also facilitates dry heat dissipation. At the same time, it is easy to release a small amount of gas generated during the long-term electrolysis process, such as water vapor in the electrolyte, so that the battery will not be heated and foamed due to long-term charging and discharging, and the diaphragm will not be deformed. Thermally conductive glue is injected into the gap between the inner surface of the rectangular flameproof and explosion-proof cup and the cylindrical electrolytic cell to prevent fire, transfer heat and dissipate heat. The rectangular flameproof and explosion-proof cup prevents the electrolytic cell from deformation and damage, and is sprayed with fire-retardant paint on the surface to separate the batteries from transferring heat to each other and causing overall damage to the battery pack. At the same time, it decomposes non-flammable inert gas due to heat to block oxygen and nitrogen from entering the battery. At the same time, it prevents the decomposed lithium crystals from coming into contact with oxygen and nitrogen during the electrolysis of the lithium battery to react and cause spontaneous combustion and explosion accidents, thereby better preventing flames and explosions.
[0028] As we all know, the structure, function and effect of batteries and capacitors are similar. The amount of electrolysis is related to the area of the electrolytic plate and the distance between the plates. The formula for capacitance is: C = Q / U. The special formula for parallel plate capacitors is: the electric field strength between the plates is E = U / d. The capacitor capacitance determination formula is C = εS / 4πkd. C = εS / 4πkd. Among them, ε is a constant, S is the area facing the capacitor plates, d is the distance between the capacitor plates, and k is the electrostatic force constant. For common parallel plate capacitors, the capacitance is C = εS / d (ε is the dielectric constant of the medium between the plates, S is the plate area, and d is the distance between the plates).
[0029] Since the purpose of the present invention is to provide a flameproof and explosion-proof lithium battery, it can avoid the essential problem of lithium battery igniting due to sparks caused by the collision of positive and negative electrodes due to internal aging and deformation of the battery due to long-term use. Therefore, the area of the positive and negative plates of the lithium battery, the distance between the two plates, and the volume of the battery are adjusted according to the actual power. The flameproof and explosion-proof cup is not limited to a rectangular parallelepiped, and the electrolytic cell is not limited to a cylinder.
Claims
1. A flameproof and explosion-proof lithium battery, comprising a lithium battery and a flameproof and explosion-proof device, characterized in that: flameproof and explosion-proof protection is provided both inside and outside the battery, including sandwiching a fireproof insulating material basalt fiber cloth or a fireproof insulating film between the positive and negative plates of the battery, an overheating protection device bimetallic strip is provided between the negative plate and the negative electrode, and the flameproof and explosion-proof cup is sprayed with fireproof paint on the outside.
2. A flameproof and explosion-proof lithium battery according to claim 1, characterized in that: Thermally conductive glue is injected into the cavity between the inner surface of the flame-proof and explosion-proof cup and the electrolytic cell.
3. The flameproof and explosion-proof lithium battery according to claim 1, characterized in that: Seal the opening with basalt fiber cloth, and then evenly apply thermal conductive glue on the sealing area.