A binder, electrode material, and battery

Abstract

The present application relates to a kind of binder, electrode material and battery, the binder includes the following preparation raw materials: temperature sensitive polymer and conductive agent;The temperature sensitive polymer includes at least one of polyalkyl pyrrole, polyalkyl thiophene, polymethyl methacrylate, ethylene-vinyl acetate copolymer, polypropylene or polyimide.The temperature sensitive polymer of the present application can change its structure and properties when temperature rises, thereby adjusting the conductive performance, bonding performance and mechanical strength of material, enabling the binder to automatically insulate the reaction in the battery, prevent thermal runaway from occurring, and the stability of the binder at high temperature is good, will not decompose or degrade to release toxic gas, greatly improve the safety performance of product;Combined with conductive agent, can form network structure with strong adhesion, good conductivity, heat conduction efficiency, the obtained binder has good adhesion and conductivity at room temperature, and excellent insulation and safety performance at high temperature.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and more particularly to an adhesive, electrode material, and battery. Background Technology

[0002] In the fields of electrochemical energy, polymer materials, and chemical engineering, battery technology research and development has always been a key focus. Lithium-ion batteries, due to their high energy density, long lifespan, and excellent charging performance, have become the primary power source for mobile electronic devices and electric vehicles. Among lithium-ion batteries, the safety performance of the battery cell is particularly important, directly affecting the safety and reliability of the entire battery system.

[0003] In existing technologies, the main method to improve the safety performance of battery cells is to use binders. Binders are polymeric materials that help fix electrode materials, improving the mechanical strength and conductivity of the electrodes. Simultaneously, binders can also form a network structure inside the battery cell, facilitating the conduction of ions and heat.

[0004] However, existing technologies still face several challenges in improving the safety performance of battery cells. First, existing binders typically lack temperature sensitivity, thus failing to automatically respond to temperature changes and effectively prevent thermal runaway. Second, existing binders may decompose or degrade at elevated temperatures, reducing the mechanical strength and conductivity of the electrodes and releasing harmful gases, further threatening the cell's safety. Finally, the network structure formed by existing binders within the cell can also be affected by temperature, impacting ion and heat conduction efficiency. Therefore, developing a temperature-sensitive binder that automatically responds to temperature changes and improves cell safety is a crucial technological challenge. Summary of the Invention

[0005] The present invention aims to solve one of the aforementioned technical problems existing in the prior art. Therefore, one objective of the present invention is to provide an adhesive grafted with temperature-sensitive functional groups. These functional groups can change their structure and properties when the temperature rises, thereby affecting the single-cell electrical capability of the electrode, automatically insulating the internal reaction of the cell, and preventing thermal runaway.

[0006] The second objective of this invention is to provide an electrode material.

[0007] The third objective of this invention is to provide a method for preparing the above-mentioned electrode material.

[0008] The fourth objective of this invention is to provide a battery.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] A first aspect of the present invention provides an adhesive comprising the following raw materials: a temperature-sensitive polymer and a conductive agent; said temperature-sensitive polymer comprising at least one selected from polyalkylpyrrole, polyalkylthiophene, polymethyl methacrylate, ethylene-vinyl acetate copolymer, polypropylene, or polyimide.

[0011] The adhesive according to the first aspect of the present invention has at least the following beneficial effects:

[0012] The temperature-sensitive polymer used in this invention has temperature-sensitive functional groups, which can change its structure and properties when the temperature rises, thereby adjusting the conductivity, adhesion, and mechanical strength of the material. This allows the adhesive to automatically insulate the reaction inside the battery cell, preventing thermal runaway. Furthermore, the adhesive exhibits good stability at high temperatures and will not decompose or degrade to release toxic gases, greatly improving the safety performance of the product. In addition, the temperature-sensitive polymer selected in this invention has excellent adhesion. As the main raw material for achieving adhesion, it, combined with a conductive agent, can form a network structure with strong adhesion, good conductivity, and efficient heat conduction. The resulting adhesive combines good adhesion and conductivity at room temperature with excellent insulation and safety performance at high temperatures.

[0013] In some embodiments of the present invention, the conductive agent includes at least one of carbon nanotubes, conductive carbon black, acetylene black, Ketjen black, graphene, or carbon nanofibers.

[0014] In some embodiments of the present invention, the mass ratio of the temperature-sensitive polymer to the conductive agent is 1:(0.1-5).

[0015] Adding an appropriate amount of conductive agent to the adhesive can form a good conductive network, improve the conductivity and heat conduction efficiency of the adhesive, and enable the adhesive to maintain good bonding and mechanical properties.

[0016] In some embodiments of the present invention, the raw materials for preparing the adhesive further include a crosslinking agent.

[0017] In some embodiments of the present invention, the crosslinking agent includes epoxy resin.

[0018] In some embodiments of the present invention, the crosslinking agent is present in the raw materials for preparing the adhesive at a mass percentage of 1 to 10 wt%.

[0019] Adding a crosslinking agent (such as epoxy resin) to the adhesive can form chemical bonds at high temperatures, thereby enhancing the mechanical properties and thermal stability of the adhesive, preventing it from decomposing, degrading or releasing toxic gases at high temperatures, and thus improving the performance and safety of the material.

[0020] A second aspect of the present invention provides an electrode material comprising an electrode active material bonded by a cured material, said cured material being formed from an adhesive comprising the binder described in the first aspect of the present invention.

[0021] The electrode material according to the second aspect of the present invention has at least the following beneficial effects:

[0022] The binder provided in the first aspect of this invention has good adhesion, which can effectively fix the electrode active material and improve the mechanical strength and conductivity of the electrode material. At the same time, the binder can also form a network structure inside the electrode material, which helps to conduct electrons, ions and heat. This network structure also has good high-temperature stability and is not easy to decompose, degrade or release toxic gases in high-temperature environments. Therefore, the resulting electrode material has good electrical conductivity, thermal conductivity and high-temperature stability. Furthermore, the temperature-sensitive polymer in the binder will automatically respond to temperature changes. When the temperature rises, the temperature-sensitive functional groups on the polymer will change their structure and properties, thereby reducing the conductivity of the electrode, automatically insulating the reaction on the electrode and preventing thermal runaway.

[0023] In some embodiments of the present invention, the electrode material includes a positive electrode material.

[0024] The binder provided by this invention is particularly suitable for the preparation of cathode materials, and is used to improve the bonding stability, electrical conductivity, thermal conductivity, high-temperature stability, high-temperature insulation and safety of cathode materials.

[0025] In some embodiments of the present invention, the cured product comprises a network structure formed by the temperature-sensitive polymer and the conductive agent.

[0026] Temperature-sensitive polymers and conductive agents form a network structure to bond and fix the electrode active material. This network structure can effectively cooperate with the electrode active material to improve conductivity. The resulting electrode material has good electrical conductivity, thermal conductivity and high-temperature stability.

[0027] In some embodiments of the present invention, the mass ratio of the cured material to the electrode active material is 1:(10-50).

[0028] By controlling the specific proportions of cured material and electrode active material, the conductive network structure formed by the binder can be optimized, and the conductivity and mechanical properties of the electrode material can be adjusted to give it better overall performance.

[0029] A third aspect of the present invention provides a method for preparing the electrode material described in the second aspect of the present invention, comprising the following steps: mixing a binder with an electrode active material to obtain a precursor, and curing the precursor to obtain the electrode material.

[0030] The method for preparing the electrode material according to the third aspect of the present invention has at least the following beneficial effects:

[0031] The electrode material preparation method provided by this invention is simple and easy to implement, and can produce electrode materials with high conductivity, high stability and high safety.

[0032] In some embodiments of the present invention, the curing temperature is 100–180°C.

[0033] In some embodiments of the present invention, the curing time is 0.5 to 5 hours.

[0034] By controlling the curing conditions, the network structure formed by the binder after curing can be optimized, thereby improving the mechanical strength and conductivity of the electrode material.

[0035] A fourth aspect of the present invention provides a battery in which the raw materials for preparing the positive electrode material include the binder described in the first aspect of the present invention; or, the positive electrode material of the battery includes the electrode material described in the second aspect of the present invention; or, the positive electrode material of the battery is prepared by a method comprising the preparation method described in the third aspect of the present invention.

[0036] The battery according to the fourth aspect of the present invention has at least the following beneficial effects:

[0037] The binder provided by this invention can form a good conductive network structure, and in particular, it can cooperate with the electrode active material to promote the bonding and fixation of the material and improve the conductivity. The resulting electrode material has good conductivity at room temperature and can effectively reduce conductivity at high temperature, achieving insulation and preventing thermal runaway, thereby obtaining a battery with good conductivity, stability and safety. Attached Figure Description

[0038] Figure 1 This is a SEM image of the positive electrode sheet obtained in Example 1 of the present invention. Detailed Implementation

[0039] The embodiments of the present invention are described in detail below. These embodiments are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. The term "comprising" and other equivalent descriptive methods used in the specification and claims of this application are intended to cover a non-exclusive inclusion, which includes both the contents explicitly described in the specification and claims and steps or units that are not described in the specification and claims but are inherent in the product, method, or structure.

[0040] A first aspect of the present invention provides an adhesive comprising the following raw materials: a temperature-sensitive polymer and a conductive agent; the temperature-sensitive polymer comprising at least one of polyalkylpyrrole, polyalkylthiophene, polymethyl methacrylate, ethylene-vinyl acetate copolymer, polypropylene, or polyimide.

[0041] The temperature-sensitive polymer used in this invention has temperature-sensitive functional groups, which can change its structure and properties when the temperature rises, thereby adjusting the conductivity, adhesion, and mechanical strength of the material. This allows the adhesive to automatically insulate the reaction inside the battery cell, preventing thermal runaway. Furthermore, the adhesive exhibits good stability at high temperatures and will not decompose or degrade to release toxic gases, greatly improving the safety performance of the product. In addition, the temperature-sensitive polymer selected in this invention has excellent adhesion. As the main raw material for achieving adhesion, it, combined with a conductive agent, can form a network structure with strong adhesion, good conductivity, and efficient heat conduction. The resulting adhesive combines good adhesion and conductivity at room temperature with excellent insulation and safety performance at high temperatures.

[0042] In some embodiments of the present invention, the temperature-sensitive polymer includes one of polyalkylpyrrole, polyalkylthiophene, polymethyl methacrylate, ethylene-vinyl acetate copolymer, polypropylene, or polyimide; in some specific embodiments of the present invention, the temperature-sensitive polymer includes one of polyalkylpyrrole, polyalkylthiophene, polymethyl methacrylate, ethylene-vinyl acetate copolymer, or polypropylene.

[0043] In some embodiments of the present invention, the conductive agent includes at least one of carbon nanotubes, conductive carbon black (SP), acetylene black, Ketjen black, graphene, or carbon nanofibers; in some specific embodiments of the present invention, the conductive agent includes at least one of carbon nanotubes, conductive carbon black (SP), acetylene black, or Ketjen black; in some examples of the present invention, the conductive agent includes carbon nanotubes, conductive carbon black (SP), or combinations thereof.

[0044] In some embodiments of the present invention, the mass ratio of the temperature-sensitive polymer to the conductive agent is 1:(0.1-5); in some specific embodiments of the present invention, the mass ratio of the temperature-sensitive polymer to the conductive agent is 1:(0.3-3); in some examples of the present invention, the mass ratio of the temperature-sensitive polymer to the conductive agent is 1:(0.5-2); non-limiting specific examples include 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.5, 1:1.8, and 1:2.

[0045] Adding an appropriate amount of conductive agent to the adhesive can form a good conductive network, improve the conductivity and heat conduction efficiency of the adhesive, and enable the adhesive to maintain good bonding and mechanical properties.

[0046] In some embodiments of the present invention, the raw materials for preparing the adhesive further include a crosslinking agent; in some specific embodiments of the present invention, the crosslinking agent includes epoxy resin.

[0047] In some embodiments of the present invention, the crosslinking agent accounts for 1 to 10 wt% of the raw materials for preparing the adhesive; in some specific embodiments of the present invention, the crosslinking agent accounts for 2 to 8 wt% of the raw materials for preparing the adhesive; in some examples of the present invention, the crosslinking agent accounts for 3 to 7 wt% of the raw materials for preparing the adhesive. Non-limiting specific examples include 3 wt%, 4 wt%, 5 wt%, 6 wt%, and 7 wt%.

[0048] Adding a crosslinking agent (such as epoxy resin) to the adhesive can form chemical bonds at high temperatures, thereby enhancing the mechanical properties and thermal stability of the adhesive, preventing it from decomposing, degrading or releasing toxic gases at high temperatures, and thus improving the performance and safety of the material.

[0049] In some embodiments of the present invention, the raw materials for preparing the adhesive further include a solvent; in some specific embodiments of the present invention, the solvent in the adhesive is selected from organic solvents; in some examples of the present invention, the solvent in the adhesive is selected from N-methylpyrrolidone (NMP). The temperature-sensitive polymer of the present invention exhibits good solubility, particularly in N-methylpyrrolidone (NMP).

[0050] In some embodiments of the present invention, the mass ratio of the temperature-sensitive polymer to the solvent is 1:(5-15); in some specific embodiments of the present invention, the mass ratio of the temperature-sensitive polymer to the solvent is 1:(6-12); in some examples of the present invention, the mass ratio of the temperature-sensitive polymer to the solvent is 1:(8-10). Non-limiting specific examples include 1:8, 1:8.5, 1:9, 1:9.5, and 1:10.

[0051] A second aspect of the present invention provides an electrode material comprising an electrode active material bonded by the cured material, the cured material being formed from an adhesive comprising the first aspect of the present invention.

[0052] The binder provided in the first aspect of this invention has good adhesion, which can effectively fix the electrode active material and improve the mechanical strength and conductivity of the electrode material. At the same time, the binder can also form a network structure inside the electrode material, which helps to conduct electrons, ions and heat. This network structure also has good high-temperature stability and is not easy to decompose, degrade or release toxic gases in high-temperature environments. Therefore, the resulting electrode material has good electrical conductivity, thermal conductivity and high-temperature stability. Furthermore, the temperature-sensitive polymer in the binder will automatically respond to temperature changes. When the temperature rises, the temperature-sensitive functional groups on the polymer will change their structure and properties, thereby reducing the conductivity of the electrode, automatically insulating the reaction on the electrode and preventing thermal runaway.

[0053] In some embodiments of the present invention, the electrode material includes a positive electrode material.

[0054] The binder provided by this invention is particularly suitable for the preparation of cathode materials, and is used to improve the bonding stability, electrical conductivity, thermal conductivity, high-temperature stability, high-temperature insulation and safety of cathode materials.

[0055] In some embodiments of the present invention, the electrode active material includes a positive electrode active material.

[0056] In some embodiments of the present invention, the positive electrode active material includes lithium-containing phosphates, lithium-containing transition metal oxides, or combinations thereof; in some specific embodiments of the present invention, the lithium-containing phosphate includes at least one of lithium iron phosphate, lithium manganese phosphate, or lithium manganese iron phosphate; the lithium-containing transition metal oxide includes lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, or lithium nickel cobalt manganese oxide (such as LiNiO2). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 refers to NCM333 and LiNi 0.5 Co 0.2 Mn 0.3 O2 refers to NCM523 and LiNi 0.5 Co 0.25 Mn 0.25 O2 refers to NCM211 and LiNi 0.6 Co 0.2 Mn 0.2 O2 refers to NCM622 and LiNi 0.8 Co 0.1 Mn 0.1 At least one of O2 (i.e., NCM811). It should be noted that this invention includes, but is not limited to, the above-mentioned positive electrode active material; anything that can be used as a positive electrode active material is within the scope of protection of this invention.

[0057] In some embodiments of the present invention, the cured material comprises a network structure formed of a temperature-sensitive polymer and a conductive agent.

[0058] Temperature-sensitive polymers and conductive agents form a network structure to bond and fix the electrode active material. This network structure can effectively cooperate with the electrode active material to improve conductivity. The resulting electrode material has good electrical conductivity, thermal conductivity and high-temperature stability.

[0059] In some embodiments of the present invention, the mass ratio of the cured material to the electrode active material is 1:(10-50); in some specific embodiments of the present invention, the mass ratio of the cured material to the electrode active material is 1:(12-40); in some examples of the present invention, the mass ratio of the cured material to the electrode active material is 1:(15-35). Non-limiting specific examples include 1:15, 1:20, 1:25, 1:30, and 1:35.

[0060] By controlling the specific proportions of cured material and electrode active material, the conductive network structure formed by the binder can be optimized, and the conductivity and mechanical properties of the electrode material can be adjusted to give it better overall performance.

[0061] A third aspect of the present invention provides a method for preparing an electrode material according to a second aspect of the present invention, comprising the following steps: mixing a binder with an electrode active material to obtain a precursor, and curing the precursor to obtain the electrode material.

[0062] The electrode material preparation method provided in the embodiments of the present invention is simple and easy to implement, and can produce electrode materials with high conductivity, high stability and high safety.

[0063] In some embodiments of the present invention, the curing temperature is 100–180°C; in some specific embodiments of the present invention, the curing temperature is 120–170°C; in some examples of the present invention, the curing temperature is 140–160°C. Non-limiting specific examples include 140°C, 145°C, 150°C, 155°C, and 160°C.

[0064] In some embodiments of the present invention, the curing time is 0.5 to 5 hours; in some specific embodiments of the present invention, the curing time is 0.8 to 4 hours; in some examples of the present invention, the curing time is 1 to 3 hours. Non-limiting specific examples include 1 hour, 1.5 hours, 2 hours, 2.5 hours, and 3 hours.

[0065] By controlling the curing conditions, the network structure formed by the binder after curing can be optimized, thereby improving the mechanical strength and conductivity of the electrode material.

[0066] In some embodiments of the present invention, the curing process does not require the use of a curing agent. By adjusting specific curing temperatures and curing times, effective curing of the binder can be achieved, resulting in an electrode material with a good conductive network structure; furthermore, the introduction of a curing agent may actually lead to other side reactions, affecting the conductivity of the material.

[0067] A fourth aspect of the present invention provides a battery in which the raw materials for preparing the positive electrode material include the binder of the first aspect of the present invention; or, the positive electrode material of the battery includes the electrode material of the second aspect of the present invention; or, the positive electrode material of the battery is prepared by a preparation method including the third aspect of the present invention.

[0068] The binder provided in the embodiments of the present invention can form a good conductive network structure. In particular, it can cooperate with the electrode active material to promote the bonding and fixation of the material and improve the conductivity. The resulting electrode material has good conductivity at room temperature and can effectively reduce conductivity at high temperature, achieving insulation and preventing thermal runaway, thereby obtaining a battery with good conductivity, stability and safety.

[0069] In some embodiments of the present invention, the battery's operating state can be adjusted in real time by monitoring its operating temperature; for example, the current and voltage can be adjusted to prevent the cell from overheating and avoid thermal runaway. Specifically, when the battery's operating temperature exceeds 130°C, the impedance is increased and the cell's operating current is reduced to prevent the cell from overheating and avoid thermal runaway.

[0070] The following specific embodiments further illustrate the content of the present invention in detail. It should also be understood that the following embodiments are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by those skilled in the art based on the principles described in the present invention are all within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make selections within a suitable range based on the description herein, and are not intended to be limited to the specific data in the examples below. Unless otherwise specified, the raw materials, reagents, or apparatus used in the following embodiments can be obtained from conventional commercial channels or by existing known methods.

[0071] Adhesive Example 1

[0072] An adhesive, prepared by the following steps:

[0073] Step 1: Select 1.5 parts by weight of polyalkylpyrrole as the matrix of the adhesive, dissolve it in NMP solvent to a solid content of 10%, and obtain the adhesive solution;

[0074] Step 2: Add 2 parts by mass of carbon nanotubes to the adhesive solution as a conductive agent to prepare the adhesive.

[0075] Adhesive Example 2

[0076] An adhesive, which differs from adhesive example 1 in that the polyalkylpyrrole used in this example is 2 parts by weight; the other raw materials and steps are the same as those in adhesive example 1.

[0077] Adhesive Example 3

[0078] An adhesive, which differs from adhesive example 1 in that the polyalkylpyrrole used in this example is 3 parts by weight; the other raw materials and steps are the same as those in adhesive example 1.

[0079] Adhesive Example 4

[0080] An adhesive, which differs from adhesive example 2 in that polyalkylpyrrole is replaced with polyalkylthiophene; other raw materials and steps are the same as in adhesive example 2.

[0081] Adhesive Example 5

[0082] An adhesive, which differs from adhesive example 2 in that polyalkylpyrrole is replaced with polymethyl methacrylate; other raw materials and steps are the same as in adhesive example 2.

[0083] Adhesive Example 6

[0084] An adhesive, which differs from adhesive example 2 in that the polyalkylpyrrole is replaced with an ethylene-vinyl acetate copolymer; the other raw materials and steps are the same as those in adhesive example 2.

[0085] Adhesive Example 7

[0086] An adhesive, which differs from adhesive example 2 in that polyalkylpyrrole is replaced with polypropylene; other raw materials and steps are the same as in adhesive example 2.

[0087] Adhesive Comparative Example 1

[0088] An adhesive, which differs from adhesive example 1 in that polyalkylpyrrole is replaced with polyvinylidene fluoride (PVDF); other raw materials and steps are the same as in adhesive example 1.

[0089] Electrode Example 1

[0090] A positive electrode sheet containing binder 1 obtained in Example 1 is prepared by the following steps:

[0091] Add 96.5 parts by weight of positive electrode active material (NCM622) to binder 1, mix and coat, cure at a curing temperature of 150℃ for 2 hours, and then die-cut to prepare positive electrode sheet.

[0092] The SEM image of the positive electrode obtained in Electrode Example 1 is shown below. Figure 1 As shown, from Figure 1 As can be seen, temperature-sensitive polymers and conductive agents can form a network structure, thereby achieving effective bonding and fixation of electrode active materials.

[0093] Electrode Examples 2-7 and Electrode Comparative Example 1

[0094] Electrode Examples 2-7 and Electrode Comparative Example 1 each provide a positive electrode sheet. The difference from Electrode Example 1 is that the binder in Electrode Examples 2-7 and Electrode Comparative Example 1 is replaced with the binder in Binder Examples 1-7 and Binder Comparative Example 1, respectively; other raw materials and preparation methods are the same as in Electrode Example 1.

[0095] The raw material composition of the positive electrode sheet of electrode Examples 1 to 7 and electrode Comparative Example 1 is shown in Table 1.

[0096] Table 1. Composition of the positive electrode sheet in Electrode Examples 1-7 and Electrode Comparative Example 1

[0097]

[0098]

[0099] Battery Example 1

[0100] A lithium-ion battery comprising the positive electrode sheet obtained in Example 1, the preparation steps of which are as follows:

[0101] The negative electrode formulation is Gr (graphite):CMC:SP = 96%:2%:2%. The slurry is prepared according to the above mass ratio and coated and die-cut to obtain the negative electrode sheet. Then, it is stacked with the positive electrode sheet obtained in electrode example 1 to obtain the battery cell. Then, the battery cell is obtained after liquid injection, wetting, formation, aging and capacity testing.

[0102] Battery Examples 2-7 and Battery Comparative Example 1

[0103] Battery Examples 2-7 and Battery Comparative Example 1 each provide a lithium-ion battery. The difference from Battery Example 1 is that the positive electrode in Battery Examples 2-7 and Battery Comparative Example 1 is replaced with the positive electrode in Electrode Examples 1-7 and Electrode Comparative Example 1, respectively; other raw materials and preparation methods are the same as in Battery Example 1.

[0104] Performance testing

[0105] Industry standard testing methods were used to test the conductivity of the binders in Examples 1-7 and Comparative Example 1 at 25°C and 130°C; the adhesion and sheet resistance of the positive electrode sheets in Examples 2-7 and Comparative Example 1 were tested; the number of cycles of the lithium-ion batteries in Examples 2-7 and Comparative Example 1 at 1C / 1C to reach 90% state of health (90% SOH) was tested; and the cell needle penetration pass rate was also measured. The cell needle penetration pass rate was determined as follows: a 5mm high-temperature resistant steel needle (with a 45° cone angle at the tip, and a smooth surface free of rust, oxide layer, and oil) was inserted into the test cell at a speed of 25mm / s from a direction perpendicular to the battery plates. The needle remained in the battery for 1 hour. If no smoke, explosion, or fire occurred, the needle penetration test was passed. The ratio of the number of samples that passed the needle penetration test to the total number of tested samples was calculated as the cell needle penetration pass rate.

[0106] The test results are shown in Table 2.

[0107] Table 2 Performance test results of the examples and comparative examples

[0108]

[0109]

[0110] As shown in Table 2, the binders in the embodiments of the present invention, including polyalkylpyrrole, polyalkylthiophene, polymethyl methacrylate, ethylene-vinyl acetate copolymer, and polypropylene, are polymeric materials with good temperature sensitivity. Their structures change at high temperatures, affecting the material's conductivity. The resulting lithium-ion batteries exhibit good thermal stability, high safety performance, and a high cell needle penetration pass rate. In contrast, the polyvinylidene fluoride (PVDF) used in Comparative Example 1 has poor safety performance and a significantly lower cell needle penetration pass rate. Furthermore, conductive agents such as carbon nanotubes can form a good conductive network inside the cell, thereby improving the cell's conductivity and heat transfer efficiency, resulting in good conductivity at room temperature. In the lithium-ion battery prepared in this embodiment of the invention, during the cell testing process, the cell doped with a temperature-sensitive binder can sense the cell's operating temperature and thus adjust the cell's operating state in real time. Specifically, when the operating temperature exceeds 130°C, the cell can avoid overheating by increasing impedance and reducing operating current, thereby preventing thermal runaway. The binder with temperature-sensitive functional groups provided in this embodiment of the invention effectively improves the battery's safety performance.

[0111] In summary, the temperature-sensitive polymer provided in this invention can change its structure and properties as the temperature rises, thereby adjusting the material's conductivity, adhesion, and mechanical strength. This allows the adhesive to automatically insulate the reaction within the battery cell, preventing thermal runaway. Furthermore, the adhesive exhibits good stability at high temperatures, without decomposing or degrading to release toxic gases, significantly improving product safety. Combined with a conductive agent, it can form a network structure with strong adhesion, good conductivity, and efficient heat conduction. The resulting adhesive combines good adhesion and conductivity at room temperature with excellent insulation and safety performance at high temperatures.

Claims

1. An electrode material, characterized in that, The invention includes a positive electrode active material bonded by a cured material, the cured material being formed by a binder; the binder is prepared from the following raw materials: a temperature-sensitive polymer, a conductive agent, and a solvent; the temperature-sensitive polymer includes at least one selected from polyalkylpyrrole, polyalkylthiophene, polymethyl methacrylate, polypropylene, or polyimide; the temperature-sensitive polymer is soluble in N-methylpyrrolidone; the solvent is selected from N-methylpyrrolidone; the conductive agent is selected from carbon nanotubes; the mass ratio of the temperature-sensitive polymer to the conductive agent is 1:(0.5~2); the mass ratio of the temperature-sensitive polymer to the solvent is 1:(8~10).

2. The electrode material according to claim 1, characterized in that, The cured product comprises a network structure formed by the temperature-sensitive polymer and the conductive agent; And / or, the mass ratio of the solidified material to the positive electrode active material is 1:(10~50).

3. A method for preparing the electrode material as described in claim 1 or 2, characterized in that, The process includes the following steps: mixing a binder with a positive electrode active material to obtain a precursor, and then curing the precursor to obtain the electrode material.

4. The preparation method according to claim 3, characterized in that, The curing temperature is 100~180℃; And / or, the curing time is 0.5~5h.

5. A battery, characterized in that, The positive electrode material of the battery includes the electrode material according to claim 1 or 2; or, the positive electrode material of the battery is prepared by the preparation method according to claim 3 or 4.

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