Thermal runaway self-polymerization battery and electrolyte polymerization initiation method

Abstract

The invention relates to the technical field of chemical power sources, in particular to a thermal runaway self-polymerization battery and an electrolyte polymerization initiation method. The thermal runaway self-polymerization battery comprises a liquid electrolyte and initiator microspheres, the electrolyte of the battery is in a liquid state under the normal working condition, the ionic conductivity of the electrolyte is high, and the performance is not influenced at all. The initiator and the polymer monomer are in an isolated state, the initiator can be released only when the temperature of the battery is abnormal, and the electrolyte can be polymerized. The melting point of the initiator microsphere protective film can ensure that the battery is polymerized before thermal runaway. The method is low in cost, simple in process and especially suitable for batch automatic production. Heating is not needed, spontaneous polymerization can be carried out when the temperature of the battery is abnormal, and polymerization uniformity does not need to be considered.

Description

Technical Field

[0001] This invention relates to the field of chemical power source technology, and in particular to a thermal runaway self-polymerization battery and a method for initiating electrolyte polymerization. Background Technology

[0002] Battery safety is a core concern for its widespread applications (such as electric vehicles, energy storage systems, and consumer electronics), involving aspects such as thermal runaway prevention, protection against mechanical abuse, and electrochemical stability. Batteries, as energy storage devices, inherently carry certain safety risks, especially those using organic liquid electrolyte systems. During thermal runaway, the negative electrode's SEI (Sediment Injection Layer) is destroyed, the electrolyte decomposes into flammable gases on the negative electrode surface, and the high-temperature electrolyte vaporization can easily lead to deflagration. Therefore, solid-state batteries are generally used to improve thermal runaway safety and prevent fires. There are three main approaches to solid-state batteries: oxide solid electrolytes, sulfide (halide) solid electrolytes, and polymer solid electrolytes. The first two still have many scientific problems to be solved, and their processes are complex, have extremely high environmental requirements, and require time for mass production. Polymer electrolytes currently have two approaches: one involves pre-synthesizing the polymer and mixing it into the positive and negative electrode materials to create the electrodes; the other involves mixing monomers, crosslinking agents, initiators, and liquid electrolytes, injecting the mixture into the battery, and then heating to initiate polymerization. Polymer electrolytes have a relatively simple process, but their biggest drawback is the low conductivity of solid polymer electrolytes, resulting in poor rate performance of the battery.

[0003] CN109818055A discloses a wide-temperature-range thermal runaway-proof electrolyte and a secondary lithium battery thereof. The electrolyte comprises lithium salt, polymeric monomers, additives, solvents, and a catalyst. The polymeric monomers undergo polymerization at high temperatures to form a stable polymer electrolyte, preventing battery thermal runaway and maintaining a liquid state and high conductivity at low temperatures. However, during battery use, temperature rises can occur, reaching up to 70 degrees Celsius. Furthermore, the catalyst (initiator) is mixed with the monomers and other electrolyte components, making precise control of the polymerization reaction difficult. Summary of the Invention

[0004] To improve battery safety under thermal runaway while maintaining electrochemical performance, this invention provides a thermal runaway self-polymerization battery and an electrolyte polymerization initiation method. The battery process is comparable to traditional liquid battery processes, uses universal equipment, and is suitable for large-scale production. The electrolyte polymerization initiation method is ingenious, allowing precise control of initiation conditions without affecting battery performance.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A first aspect of the present invention is to provide a thermal runaway self-polymerization battery, comprising: a liquid electrolyte and initiator microspheres;

[0007] The liquid electrolyte is composed of monomers, crosslinking agents, and liquid electrolyte solution; the mass ratio of the initiator microspheres to the monomers is (0.05-0.5):100.

[0008] Preferably, the diameter of the initiator microspheres is 0.5-5 mm.

[0009] Preferably, the initiator microspheres comprise: a protective film and an initiator located within the protective film.

[0010] More preferably, the protective film is made of an olefinic material.

[0011] More preferably, the protective film comprises at least one of polypropylene or polyethylene.

[0012] Preferably, the initiator includes azobisisobutyronitrile (AIBN).

[0013] Preferably, it includes: lithium-ion batteries and sodium-ion batteries.

[0014] A second aspect of the present invention is to provide an electrolyte polymerization initiation method for the above-mentioned thermal runaway self-polymerization battery, the steps of which include: placing a liquid electrolyte and initiator microspheres inside the battery; when the battery temperature is abnormal, the protective film of the initiator microspheres melts, and the initiator mixes with the liquid electrolyte and polymerizes rapidly.

[0015] Preferably, the melting temperature of the protective film is 100-170°C.

[0016] Preferably, the initiator microspheres are implanted into the battery through liquid injection or attached to the bottom of the cover plate before welding.

[0017] The present invention adopts the above technical solution and has the following technical effects compared with the prior art:

[0018] (1) The battery of this invention has excellent safety performance, while its electrical performance is comparable to that of traditional liquid batteries. Traditional polymer solid-state batteries are polymerized before leaving the production line and remain in a solid polymer state throughout their entire life cycle, sacrificing electrochemical performance to ensure safety. The electrolyte of the battery of this invention is in liquid form under normal operating conditions, with high ionic conductivity and no impact on performance. The initiator is isolated from the polymer monomer; the initiator is only released when the battery temperature is abnormal, and the electrolyte only polymerizes. That is, the battery of this invention requires electrolyte polymerization to polymerize. In addition, the melting point of the initiator microsphere protective film ensures that the battery polymerizes before thermal runaway.

[0019] (2) This invention is low in cost and simple in process, making it particularly suitable for mass automated production. The polymer electrolyte industry has been focused on solving the problem of ionic conductivity, which has led to increased material costs and process complexity, hindering large-scale application. This invention avoids this problem by not requiring high ionic conductivity in the polymer electrolyte and achieving extremely low material costs. Furthermore, traditional polymer solid-state battery polymerization processes are difficult to control. For example, polymerization reactions triggered by normal temperatures require heating the battery. During heating, heat is conducted from the outside of the battery casing to the inside, inevitably resulting in temperature differences between the inside and outside, leading to poor polymerization uniformity and inconsistent battery performance. This invention, however, does not require heating and can spontaneously polymerize even when the battery temperature is abnormal, eliminating the need to consider polymerization uniformity. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0022] The present invention will be further described below with reference to specific embodiments, but these are not intended to limit the scope of the invention.

[0023] Example 1

[0024] This embodiment provides a thermal runaway self-polymerization battery and an electrolyte polymerization initiation method, the steps of which include:

[0025] 1. Azobisisobutyronitrile (initiator) is heat-sealed with polyethylene film to prepare a spherical shape with a diameter of approximately 5 mm, and then attached to the underside of the battery cover. It is then welded into the battery along with the cover. The amount of azobisisobutyronitrile (initiator) used is approximately 0.4% of the methyl methacrylate monomer in the electrolyte.

[0026] 2. Mix 5% methyl methacrylate (monomer), 1% polyethylene glycol diacrylate (crosslinking agent), and 94% liquid electrolyte evenly, and then inject the mixture into the lithium-ion battery in a single injection process.

[0027] 3. After the battery is injected with electrolyte and sealed, it exists in a liquid state at operating temperatures ranging from -40℃ to 85℃, with conductivity comparable to that of traditional liquid electrolytes. If the battery temperature becomes abnormal, reaching above 130℃, the polyethylene film melts, releasing the initiator azobisisobutyronitrile (AIBN), and the electrolyte polymerizes.

[0028] Example 2

[0029] This embodiment provides another thermal runaway self-polymerization battery and electrolyte polymerization initiation method, the steps of which include:

[0030] 1. Azobisisobutyronitrile (initiator) is heat-sealed with polyethylene film to form spherical shapes with a diameter of approximately 3 mm, which are then adhered to the underside of the battery cover. It is then welded into the battery along with the cover. The amount of azobisisobutyronitrile (initiator) used is approximately 0.3% of the methyl methacrylate monomer in the electrolyte.

[0031] 2. After mixing 50% methyl methacrylate (monomer), 10% polyethylene glycol diacrylate (crosslinking agent), and 40% liquid electrolyte evenly, the mixture is injected into the lithium-ion battery in a secondary electrolyte injection process.

[0032] 3. After the battery is injected with electrolyte and sealed, it exists in a liquid state at operating temperatures ranging from -40℃ to 85℃, with conductivity comparable to that of traditional liquid electrolytes. If the battery temperature becomes abnormal, it will melt when it reaches above 130℃, releasing the initiator azobisisobutyronitrile (AIBN) and causing the electrolyte to polymerize.

[0033] Example 3

[0034] This embodiment provides another thermal runaway self-polymerization battery and electrolyte polymerization initiation method, the steps of which include:

[0035] 1. Azobisisobutyronitrile (initiator) is heat-sealed with polyethylene film to prepare spherical particles with a diameter of about 2 mm.

[0036] 2. After mixing 6% butyl acrylate (monomer), 0.8% polyoxyethylene trimethylpropane triacrylate (crosslinking agent), and 93.2% liquid electrolyte evenly, the mixture is injected into the lithium-ion battery in a single injection process.

[0037] 3. After electrolyte injection, azobisisobutyronitrile (AIBN) spheres are implanted into the battery through the injection hole. The amount of AIBN (initiator) used is approximately 0.2% of the butyl acrylate monomer in the electrolyte.

[0038] 4. After the battery is injected with electrolyte and sealed, it exists in a liquid state at operating temperatures ranging from -40℃ to 85℃, with conductivity comparable to that of traditional liquid electrolytes. If the battery temperature becomes abnormal, the polyethylene film melts when it reaches above 130℃, releasing the initiator azobisisobutyronitrile (AIBN), and the electrolyte polymerizes.

[0039] Example 4

[0040] This embodiment provides another thermal runaway self-polymerization battery and electrolyte polymerization initiation method, the steps of which include:

[0041] 1. Azobisisobutyronitrile (initiator) is heat-sealed with a polypropylene film to prepare a spherical object with a diameter of about 2 mm.

[0042] 2. After mixing 45% butyl acrylate (monomer), 5% polyoxyethylene trimethylpropane triacrylate (crosslinking agent) and 50% liquid electrolyte evenly, the mixture is injected into the lithium-ion battery in a secondary electrolyte injection process.

[0043] 3. After electrolyte injection, azobisisobutyronitrile (AIBN) spheres are implanted into the battery through the injection hole. The amount of AIBN (initiator) used is approximately 0.1% of the butyl acrylate monomer in the electrolyte.

[0044] 4. After the battery is injected with electrolyte and sealed, it exists in a liquid state at operating temperatures ranging from -40℃ to 85℃, with conductivity comparable to that of traditional liquid electrolytes. If the battery temperature becomes abnormal, it will melt when it reaches above 150℃, releasing the initiator azobisisobutyronitrile (AIBN) and causing the electrolyte to polymerize.

[0045] Example 5

[0046] This embodiment provides another thermal runaway self-polymerization battery and electrolyte polymerization initiation method, the steps of which include:

[0047] 1. Azobisisobutyronitrile (initiator) is heat-sealed with polyethylene film to prepare a 3mm diameter spherical shape, which is then attached to the underside of the battery cover. It is then welded into the battery along with the cover. The amount of azobisisobutyronitrile (initiator) used is approximately 0.5% of the methyl methacrylate monomer in the electrolyte.

[0048] 2. Mix 6% methyl methacrylate (monomer), 1% polyethylene glycol diacrylate (crosslinking agent), and 93.0% liquid electrolyte evenly, and then inject the mixture into the sodium-ion battery in a single injection process.

[0049] 3. After the battery is injected with electrolyte and sealed, it exists in a liquid state at operating temperatures ranging from -40℃ to 85℃, with conductivity comparable to that of traditional liquid electrolytes. If the battery temperature becomes abnormal, it will melt when it reaches above 130℃, releasing the initiator azobisisobutyronitrile (AIBN) and causing the electrolyte to polymerize.

[0050] Example 6

[0051] This embodiment provides another thermal runaway self-polymerization battery and electrolyte polymerization initiation method, the steps of which include:

[0052] 1. Azobisisobutyronitrile (initiator) is wrapped and sealed with polyethylene film to form a 3mm diameter spherical shape, which is then attached to the underside of the battery cover. It is then welded into the battery along with the cover and sealed inside. The amount of azobisisobutyronitrile (initiator) used is approximately 0.5% of the methyl methacrylate monomer in the electrolyte.

[0053] 2. After mixing 50% methyl methacrylate (monomer), 5% polyethylene glycol diacrylate (crosslinking agent), and 45% liquid electrolyte evenly, the mixture is injected into the sodium-ion battery in a secondary electrolyte injection process.

[0054] 3. After the battery is injected with electrolyte and sealed, it exists in a liquid state at operating temperatures ranging from -40℃ to 85℃, with conductivity comparable to that of traditional liquid electrolytes. If the battery temperature becomes abnormal, it will melt when it reaches above 130℃, releasing the initiator azobisisobutyronitrile (AIBN) and causing the electrolyte to polymerize.

[0055] Example 7

[0056] This embodiment provides another thermal runaway self-polymerization battery and electrolyte polymerization initiation method, the steps of which include:

[0057] 1. Azobisisobutyronitrile (initiator) is heat-sealed with polyethylene film to prepare spherical particles with a diameter of 1-2 mm.

[0058] 2. After mixing 8% butyl acrylate (monomer), 1% polyoxyethylene trimethylpropane triacrylate (crosslinking agent) and 91% liquid electrolyte evenly, inject the mixture into the sodium-ion battery in a single injection process.

[0059] 3. After electrolyte injection, azobisisobutyronitrile (AIBN) spheres are implanted into the battery through the injection hole. The amount of AIBN (initiator) used is approximately 0.2% of the butyl acrylate monomer in the electrolyte.

[0060] 4. After the battery is injected with electrolyte and sealed, it exists in a liquid state at operating temperatures ranging from -40℃ to 85℃, with conductivity comparable to that of traditional liquid electrolytes. If the battery temperature becomes abnormal, the polyethylene film melts when it reaches above 130℃, releasing the initiator azobisisobutyronitrile (AIBN), and the electrolyte polymerizes.

[0061] Example 8

[0062] This embodiment provides another thermal runaway self-polymerization battery and electrolyte polymerization initiation method, the steps of which include:

[0063] 1. Azobisisobutyronitrile (initiator) is heat-sealed with a polypropylene film to prepare spherical particles with a diameter of 1-2 mm.

[0064] 2. After mixing 40% butyl acrylate (monomer), 5% polyoxyethylene trimethylpropane triacrylate (crosslinking agent) and 55% liquid electrolyte evenly, the mixture is injected into the sodium-ion battery in a secondary electrolyte injection process.

[0065] 3. After electrolyte injection, azobisisobutyronitrile (AIBN) spheres are implanted into the battery through the injection hole. The amount of AIBN (initiator) used is approximately 0.1% of the butyl acrylate monomer in the electrolyte.

[0066] 4. After the battery is injected with electrolyte and sealed, it exists in a liquid state at operating temperatures ranging from -40℃ to 85℃, with conductivity comparable to that of traditional liquid electrolytes. If the battery temperature becomes abnormal, it will melt when it reaches above 150℃, releasing the initiator azobisisobutyronitrile (AIBN) and causing the electrolyte to polymerize.

[0067] Comparative Example 1

[0068] This comparative example provides a conventional polymer solid-state battery.

[0069] 1. Mix 5% methyl methacrylate (monomer), 1% polyethylene glycol diacrylate (crosslinking agent), and 94% liquid electrolyte evenly, then add azobisisobutyronitrile (initiator) at a weight of 0.4% of the methyl methacrylate amount, and mix evenly.

[0070] 2. The prepared battery is injected into the prepared electrolyte and sealed, and polymerized at 65°C.

[0071] Detection Examples

[0072] To observe the polymerization effect, the cells were sealed without welding after electrolyte injection. A 0.5mm thick transparent sheet of polyethylene terephthalate (PET) was glued to the injection hole with UV adhesive to facilitate observation. Finally, a thermal runaway test was used for verification. The polymerization results of Examples 1-8 are shown in Table 1.

[0073] Table 1

[0074]

[0075]

[0076] The performance of the batteries in Example 1 and Comparative Example 1 was tested respectively, and the results are shown in Table 2.

[0077] Table 2

[0078] Capacity(Ah) Internal resistance (mΩ) Capacity retention after 300 cycles (%) Example 1 53 0.62 96.7 Comparative Example 1 46 2.79 72.6

[0079] As shown in Tables 1-2, the electrolyte polymerization initiation method of the battery of the present invention can precisely control the polymerization before the battery thermal runaway. The melting point of the separator of the battery cell in the example is greater than the melting point of the initiator microsphere protective film. Moreover, the electrolyte of the battery of the present invention is in liquid form under normal working conditions. The electrolyte has high ionic conductivity and all performance is better than that of traditional solid-state batteries. That is, the battery of the present invention does not need to sacrifice the battery chemical performance to ensure safety.

[0080] The above description is merely a preferred embodiment of the present invention and does not limit the implementation and protection scope of the present invention. Those skilled in the art should realize that any equivalent substitutions and obvious changes made based on the content of this specification should be included within the protection scope of the present invention.

Claims

1. A thermal runaway self-polymerizing battery, characterized in that, include: Liquid electrolyte and initiator microspheres; The liquid electrolyte is composed of monomers, crosslinking agents, and liquid electrolyte solution; the mass ratio of the initiator microspheres to the monomers is (0.05-0.5):

100.

2. The thermal runaway self-polymerization battery according to claim 1, characterized in that, The initiator microspheres have a diameter of 0.5-5 mm.

3. The thermal runaway self-polymerization battery according to claim 1, characterized in that, The initiator microspheres include a protective film and an initiator located within the protective film.

4. The thermal runaway self-polymerization battery according to claim 3, characterized in that, The protective film is made of olefin-based materials.

5. The thermal runaway self-polymerization battery according to claim 4, characterized in that, The protective film includes at least one of polypropylene or polyethylene.

6. The thermal runaway self-polymerization battery according to claim 3, characterized in that, The initiator includes azobisisobutyronitrile (AIBN).

7. The thermal runaway self-polymerization battery according to claim 1, characterized in that, include: Lithium-ion batteries and sodium-ion batteries.

8. A method for initiating electrolyte polymerization in a thermal runaway self-polymerizing battery as described in any one of claims 1-7, characterized in that the step include: Liquid electrolyte and initiator microspheres are placed inside the battery. When the battery temperature is abnormal, the protective film of the initiator microspheres melts, and the initiator mixes with the liquid electrolyte and polymerizes rapidly.

9. The electrolyte polymerization initiation method according to claim 8, characterized in that, The protective film melts at a temperature of 100-170℃.

10. The electrolyte polymerization initiation method according to claim 8, characterized in that, The initiator microspheres are implanted into the battery through liquid injection or attached to the bottom of the cover plate before welding.

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