Lithium supplement, preparation method thereof, positive electrode sheet, battery and electrical equipment

Abstract

The present invention provides a lithium supplement agent, a preparation method thereof, a positive electrode plate, a battery, and an electrical device. The lithium supplement agent provided by the present invention includes a lithium supplement material and an active oxygen quencher present on at least a portion of the surface of the lithium supplement material; the active lithium supplement material is grafted with a first amino group; and the active oxygen quencher is connected to the lithium supplement material via the first amino group. The lithium supplement agent provided by the present invention has the active oxygen quencher present on at least a portion of the surface of the lithium supplement material, which can quench generated active oxygen, reduce battery gas production, that is, reduce the risk of battery expansion, and reduce side reactions between active oxygen and electrolyte and electrolyte consumption. At the same time, it can increase the porosity of the electrode plate, thereby improving the battery's rate discharge performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries, and in particular relates to a lithium supplement and a preparation method thereof, a positive electrode sheet, a battery and an electrical device. Background Art

[0002] To compensate for the loss of active lithium due to SEI film formation during the battery's initial charge, a lithium supplement is typically added to the battery slurry to offset this loss of active lithium and thereby extend the battery's cycle life. However, the introduction of a lithium supplement increases the risk of active oxygen release, leading to gassing and bulging of the battery. Summary of the Invention

[0003] The main purpose of the present invention is to provide a lithium supplement agent, which can reduce the gas production of the battery, increase the porosity of the electrode, and thus improve the rate discharge performance of the battery.

[0004] The present invention also provides a method for preparing a lithium supplement, which can prepare the lithium supplement, has a simple process and low cost.

[0005] The present invention also provides a positive electrode sheet comprising the above-mentioned lithium supplement agent. Therefore, the positive electrode sheet has a high porosity and can be applied to a battery to reduce the gas production of the battery and improve the rate discharge performance of the battery.

[0006] The present invention also provides a battery comprising the above-mentioned positive electrode sheet. Therefore, the battery has a low gas production and a high porosity of the positive electrode sheet, thereby improving the rate discharge performance of the battery.

[0007] The present invention also provides an electrical device comprising the above-mentioned battery. Therefore, the performance of the battery related to the electrical device is relatively excellent.

[0008] In a first aspect, the present invention provides a lithium supplement agent, comprising a lithium supplement material and an active oxygen quencher present on at least a portion of the surface of the lithium supplement material;

[0009] The lithium supplement material is grafted with a first amino group;

[0010] The active oxygen quencher is connected to the lithium supplementing material via the first amino group.

[0011] In the lithium supplement agent as described above, the first amino group is connected to the active oxygen quencher via an intermediate functional group.

[0012] In the lithium supplement agent as described above, the active oxygen quencher includes a second amino group, and the first amino group is connected to the second amino group through the intermediate functional group.

[0013] In the lithium supplement as described above, the active oxygen quencher includes at least one of triphenylamine, 2-aminoimidazole, 1-(3-aminopropyl)imidazole, 4-amino-1,2,4-triazole, chitosan, dopamine and derivatives thereof.

[0014] In the lithium supplement as described above, the active oxygen quencher accounts for 0.5% to 2.5% by mass of the lithium supplement.

[0015] In the lithium supplement agent as described above, the intermediate functional group includes an ether group.

[0016] As mentioned above, the lithium supplement material is Li x M y O z , wherein M includes at least one of C, Fe, Co, Ni, Mn and Cr, x≥2, y≥1, z≥1, preferably 2≤x≤7, 1≤y≤4, 1≤z≤6.

[0017] In the lithium supplement agent as described above, the lithium supplement material includes at least one of Li5FeO4, Li2NiO2, Li2C2O4, and Li6CoO4.

[0018] In a second aspect, the present invention provides a method for preparing the lithium supplement as described above, comprising the following steps:

[0019] 1) performing an amination treatment on the lithium-supplementing material to obtain an amination lithium-supplementing material;

[0020] 2) Grafting the active oxygen quencher onto the amino lithium-supplementing material to obtain the lithium-supplementing agent.

[0021] According to the preparation method described above, the step of grafting an active oxygen quencher onto the amino lithium-supplementing material to obtain the lithium-supplementing agent comprises:

[0022] Performing a first reaction on a first system including the amino lithium-supplementing material and a compound containing an intermediate functional group to obtain a first intermediate;

[0023] A second reaction is performed on a second system including the first intermediate and the active oxygen quencher to obtain the lithium supplement agent.

[0024] According to the preparation method described above, the active oxygen quencher includes a second amino group.

[0025] The preparation method as described above, wherein the lithium supplementing material is subjected to an amination treatment using an amino-containing modifier;

[0026] The amino-containing modifier includes at least one of diethylenetriamine, ethylenediaminetetraacetic acid, carbamic acid and glycine.

[0027] In the preparation method described above, the compound containing an intermediate functional group includes a compound containing an epoxy group, and the compound containing an epoxy group includes at least one of diglycidyl ether, ethylene glycol diglycidyl ether, and 1,4-butanediol diglycidyl ether.

[0028] In the preparation method described above, the molar ratio of the lithium-supplementing material to the compound containing the intermediate functional group is 1:(1.5-5).

[0029] In the preparation method described above, the molar ratio of the lithium-supplementing material to the amino-containing modifier is 1:(1.5-5).

[0030] In the preparation method described above, the molar ratio of the lithium supplement material to the active oxygen quencher is 1:(2-4).

[0031] In a third aspect, the present invention provides a positive electrode sheet comprising the lithium supplement agent as described above or the lithium supplement agent prepared by the preparation method as described above.

[0032] The positive electrode sheet as described above includes a positive electrode active material, and the mass ratio of the lithium supplement agent to the positive electrode active material is 0.1%-3%.

[0033] In a fourth aspect, the present invention provides a battery comprising the positive electrode sheet as described above.

[0034] In a fifth aspect, the present invention provides an electrical device comprising the battery as described above.

[0035] The lithium supplement provided by the present invention contains an active oxygen quencher on at least a portion of the surface of the lithium supplement material. This quenches the generated active oxygen, reducing battery gas production, thereby reducing the risk of battery expansion. It also reduces side reactions between active oxygen and electrolyte, as well as electrolyte consumption. Furthermore, it increases the porosity of the electrode, thereby improving the battery's rate discharge performance. Furthermore, the active oxygen quencher is linked to the lithium supplement material via a first amino group, enhancing the chemical stability of the lithium supplement. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the following briefly introduces the drawings required for use in the embodiments of the present invention or related technologies. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0037] Figure 1 Schematic diagram of the interfaces of the batteries of Examples 1 to 5 of the present invention and Comparative Example 1;

[0038] Figure 2Graph showing gas production of batteries according to Examples 1 to 5 of the present invention and Comparative Example 1;

[0039] Figure 3 Schematic diagram of the interface of the battery of Example 1, Example 11-Example 14 of the present invention;

[0040] Figure 4 Graphs showing the porosity of the positive electrode sheets of Examples 1, 11, and 14 of the present invention;

[0041] Figure 5 This is a schematic diagram of the preparation process of the lithium supplement provided by the present invention. DETAILED DESCRIPTION

[0042] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0043] Lithium-ion batteries are widely used in consumer electronics, electric vehicles, and energy storage systems due to their high energy density and long cycle life. However, problems such as battery capacity decay and reduced lifespan caused by the loss of active lithium remain to be solved. Researchers have proposed lithium replenishment technologies to compensate for the loss of active lithium. However, as the lithium replenishment materials decompose, reactive oxygen species are generated. In addition, reactive oxygen species may be generated during the charge and discharge process of the battery, especially under high voltage or overcharge conditions. The generation of these reactive oxygen species is mainly related to the structural instability of the positive electrode active material, especially in high-voltage positive electrode active materials such as high-nickel ternary materials and lithium cobalt oxide.

[0044] The generation of reactive oxygen species presents two major problems. First, reactive oxygen species may be released as oxygen, causing increased internal pressure in the battery and potentially leading to battery swelling. This physical deformation not only compromises the structural integrity of the battery but can also lead to safety hazards such as leakage or explosion. Second, reactive oxygen species react with the electrolyte, leading to electrolyte consumption. This reaction not only reduces the electrolyte's effectiveness but can also generate unstable byproducts, further impacting the battery's electrochemical performance and cycle life.

[0045] In order to meet these challenges, the inventors of this application have discovered through research that by grafting a substance that can quench active oxygen onto the surface of the lithium-supplementing material, the substance can react with the active oxygen, reduce the gas production of the battery, and reduce the consumption of the electrolyte.

[0046] Based on this, in a first aspect, the present invention provides a lithium supplement agent, comprising a lithium supplement material and an active oxygen quencher present on at least a portion of the surface of the lithium supplement material; the lithium supplement material is grafted with a first amino group; and the active oxygen quencher is connected to the lithium supplement material via the first amino group.

[0047] The lithium supplement agent of the present invention can quench active oxygen, reduce the gas production of the battery, and at the same time, increase the porosity of the electrode, thereby improving the battery's rate discharge performance. This is because when the lithium supplement agent decomposes, the active oxygen quencher can effectively capture and neutralize the active oxygen generated, thereby reducing the internal pressure of the battery, reducing the risk of battery expansion, and improving the safety of the battery. It can also reduce the side reactions between active oxygen and the electrolyte, thereby replenishing active lithium while reducing the adverse effects of side reactions on battery life, extending the battery's service life, and reducing electrolyte consumption and maintaining electrolyte stability. At the same time, the lithium supplement agent can increase the porosity of the electrode after decomposition. The nitrogen atom in the first amino group in the lithium supplement agent has a high electron density and can form hydrogen bonds with solvent molecules in the electrolyte, which can enhance the wettability of the electrolyte, strengthen the liquid phase mass transfer capacity of the electrode, reduce the overall polarization of the battery, and improve the uniformity of lithium insertion and extraction in the electrode, thereby improving the battery's rate discharge performance. It is particularly suitable for thick electrode systems.

[0048] In addition, the active oxygen quencher is connected to the lithium supplement material through the first amino group. The chemical bond formed by the amino group is usually highly stable and can achieve stable chemical bonding, making the structure more solid and stable, not prone to dissociation, and having higher chemical stability.

[0049] The lithium supplement provided by the present invention incorporates an active oxygen quencher on at least a portion of the surface of the lithium supplement material. This quenches generated active oxygen, reducing battery gas production (i.e., the risk of battery expansion), side reactions between active oxygen and electrolyte, and electrolyte consumption. Furthermore, it increases the porosity of the electrode, thereby improving the battery's rate discharge performance. Furthermore, the active oxygen quencher is linked to the lithium supplement material via a first amino group, enhancing the chemical stability of the lithium supplement.

[0050] In some embodiments of the present invention, the first amino group is connected to the active oxygen quencher via an intermediate functional group. The presence of the intermediate functional group facilitates better connection between the lithium supplement material and the active oxygen quencher, further improving the stability of the lithium supplement material.

[0051] In some embodiments of the present invention, the active oxygen quencher includes a second amino group, and the first amino group is connected to the second amino group through an intermediate functional group, which is conducive to better connection between the lithium supplement material and the active oxygen quencher and further improves the stability of the lithium supplement agent.

[0052] In some embodiments of the present invention, the active oxygen quencher includes at least one of triphenylamine, 2-aminoimidazole, 1-(3-aminopropyl)imidazole, 4-amino-1,2,4-triazole, chitosan, dopamine and derivatives thereof.

[0053] The types of active oxygen quenchers in the present invention include the above range, which can effectively capture and neutralize active oxygen, reduce the gas production of the battery, reduce the risk of battery expansion, improve the safety of the battery, and also reduce the side reactions between active oxygen and electrolyte and the consumption of electrolyte, thereby improving the cycle life and capacity retention of the battery.

[0054] In some embodiments of the present invention, the mass proportion of the active oxygen quencher in the lithium supplement is 0.5%-2.5%, for example, it can be 0.5%, 1%, 1.5%, 2%, 2.5% or any two thereof.

[0055] In the present invention, by controlling the mass proportion of the active oxygen quencher to 0.5%-2.5%, it can be ensured that the active oxygen quencher is sufficient to effectively capture and neutralize the active oxygen without excessively causing material waste or triggering unnecessary side reactions, thereby further reducing the gas production of the battery, reducing the risk of battery expansion, and improving the safety of the battery. It can also reduce the side reactions between active oxygen and electrolyte and the consumption of electrolyte, thereby improving the cycle life and capacity retention of the battery.

[0056] In some embodiments of the present invention, the intermediate functional group comprises an ether group.

[0057] The present invention uses an ether group as an intermediate functional group. Ether groups have high molecular flexibility and can serve as a bridge to connect different chemical groups. They also have good chemical stability, remain stable in the battery operating environment, and are not susceptible to decomposition, facilitating the connection between the lithium-supplementing material and the active oxygen quencher. Furthermore, the stability and inertness of the ether group prevent the active oxygen quencher from dissociating, improving the overall stability and safety of the battery.

[0058] In some embodiments of the present invention, the lithium supplement material is Li x M y O z , wherein M includes at least one of C, Fe, Co, Ni, Mn and Cr, x≥2, y≥1, z≥1, preferably 2≤x≤7, 1≤y≤4, 1≤z≤6.

[0059] Illustratively, x can be 2, 3, 4, 5, 6, 7, 8, 9, 10 or a range consisting of any two thereof; y can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or a range consisting of any two thereof; z can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or a range consisting of any two thereof.

[0060] The lithium supplement material in the present invention may be a material having a chemical composition of Li x M y O z Any single material among the materials, or a composite material of two or more of the above materials.

[0061] The lithium supplement material of the present invention can provide an additional lithium source to compensate for the lithium loss caused by the decomposition of the electrolyte and the formation of the solid electrolyte interface (SEI) film, thereby improving the cycle performance and stability of the battery.

[0062] Preferably, the lithium supplement material includes at least one of Li5FeO4, Li2NiO2, Li2C2O4, and Li6CoO4, which can further compensate for the lithium loss caused by the decomposition of the electrolyte and the formation of the solid electrolyte interface (SEI) film, thereby improving the cycle performance and stability of the battery.

[0063] In some embodiments of the present invention, the present invention provides a method for preparing the lithium supplement as described above, comprising the following steps:

[0064] 1) performing an amination treatment on the lithium-supplementing material to obtain an amination lithium-supplementing material;

[0065] 2) Grafting an active oxygen quencher onto the amino lithium-replenishing material to obtain a lithium-replenishing agent.

[0066] The preparation method of the lithium supplement agent of the present invention is as follows: Figure 5 As shown, the surface of the lithium-replenishing material is subjected to amino treatment, and then the active oxygen quencher is grafted onto the surface of the lithium-replenishing material by chemical bonding.

[0067] Introducing amino groups on the surface of lithium-supplementing materials can improve the reactivity and surface functionality of lithium-supplementing materials and provide active sites for subsequent grafting reactions.

[0068] Grafting an active oxygen quencher on the surface of the aminated lithium-supplementing material can enhance the active oxygen quenching ability of the lithium-supplementing material, reduce the damage of active oxygen to the battery, reduce the gas production of the battery, and improve the safety of the battery.

[0069] The preparation method of the lithium supplement agent of the present invention has mild reaction conditions, does not require an additional protective atmosphere, and has a simple preparation process. By grafting an active oxygen quencher onto the surface of the lithium supplement material, the resulting lithium supplement agent with the grafted active oxygen quencher can quench the active oxygen generated during the decomposition of the lithium supplement agent, reducing battery gas production, thereby reducing the risk of battery expansion, and reducing side reactions between active oxygen and electrolyte and electrolyte consumption. Furthermore, the porosity of the electrode can be increased.

[0070] In some embodiments of the present invention, grafting an active oxygen quencher onto an aminated lithium-supplementing material to obtain a lithium-supplementing agent comprises: performing a first reaction on a first system comprising an aminated lithium-supplementing material and a compound containing an intermediate functional group to obtain a first intermediate; and performing a second reaction on a second system comprising the first intermediate and the active oxygen quencher to obtain the lithium-supplementing agent.

[0071] In a specific implementation, the amino lithium supplement material and an excess of a compound containing an intermediate functional group can be added to a reaction solvent to obtain a first solution; the first solution is placed at a first temperature and stirred for a first reaction time. After the reaction is completed, the first centrifugal washing is performed at least 3 times with the same reaction solvent, and the precipitate is dried.

[0072] The above precipitate is placed in a reaction solvent, stirred and dispersed evenly, and then an active oxygen quencher is added to obtain a second solution; the second solution is placed at a second temperature and stirred for a second time. After the reaction is completed, a second centrifugal washing is performed at least three times with the same reaction solvent, and the precipitate is dried to obtain a lithium supplement grafted with an active oxygen quencher.

[0073] In the present invention, the first temperature and the second temperature can be 80-100°C, the first time and the second time can be 10-12 hours, the speed of the first centrifugation and the second centrifugation can be 6000-12000 rpm, and the centrifugation time can be 5-15 minutes.

[0074] In the first reaction of the present invention, the aminated lithium-replenishing material reacts with a compound containing an intermediate functional group to form a stable first intermediate. This step ensures the effective bonding of the intermediate functional group with the first amino group in the lithium-replenishing material, providing an active platform for the subsequent grafting reaction. In the second reaction, the first intermediate reacts with an active oxygen quencher, connecting the first amino group to the active oxygen quencher via the intermediate functional group to form the final lithium-replenishing agent. This step-by-step approach improves the grafting efficiency of the active oxygen quencher and ensures its uniform distribution on the material surface.

[0075] In some embodiments of the present invention, the active oxygen quencher includes a second amino group, and the first amino group can be connected to the second amino group through an intermediate functional group, thereby realizing the connection between the lithium supplement material and the active oxygen quencher and further improving the stability of the lithium supplement agent.

[0076] In some embodiments of the present invention, the lithium supplementing material is subjected to amination treatment using an amino-containing modifier; the amino-containing modifier includes at least one of diethylenetriamine, ethylenediaminetetraacetic acid, carbamic acid and glycine.

[0077] The preparation method of the present invention comprises dispersing a lithium-supplementing material in a reaction solvent, adding an amino-containing modifier, and stirring the reaction at a third temperature for a third time. After the reaction is complete, the material is filtered and dried to obtain the amino-supplementing material. The reaction solvent may be selected from at least one of N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, dimethylacetamide, and isophorone. The third temperature may be 80°C to 100°C, and the third time may be 10 to 12 hours.

[0078] The type of amino-containing modifier is within the above range, which can form a stable amino layer on the surface of the lithium-supplementing material, provide a good reaction site for the subsequent grafting of epoxy-containing compounds, and ensure the stability of chemical bonds.

[0079] In some embodiments, the compound containing an intermediate functional group includes an epoxy-containing compound, and the epoxy-containing compound includes at least one of diglycidyl ether, ethylene glycol diglycidyl ether, and 1,4-butanediol diglycidyl ether.

[0080] The epoxy group-containing compound is within the above range and has high reactivity, and can react quickly with the amino group on the surface of the lithium supplementing material to form a stable chemical bond.

[0081] In some embodiments, the molar ratio of the lithium supplementing material to the compound containing the intermediate functional group is 1:(1.5-5), for example, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5 or a range consisting of any two thereof.

[0082] The molar ratio of the lithium-supplementing material to the compound containing the intermediate functional group is within the above range, which can ensure that the intermediate functional group fully reacts with the first amino group in the lithium-supplementing material to form a stable chemical bond and enhance the structural stability of the material.

[0083] In some embodiments of the present invention, the molar ratio of the lithium supplementing material to the amino group-containing modifier is 1:(1.5-5), for example, it can be 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5 or a range consisting of any two thereof.

[0084] In the present invention, the molar ratio of the lithium-supplementing material to the amino-containing modifier is within the above range. By providing an excess of the amino-containing modifier, the surface of the lithium-supplementing material can be ensured to be fully aminated, thereby increasing the number of reactive sites and improving the efficiency of the subsequent grafting reaction.

[0085] In some embodiments, the molar ratio of the lithium replenishing material to the active oxygen quencher is 1:(2-4), for example, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, or a range consisting of any two thereof.

[0086] The molar ratio of the lithium replenishing material to the active oxygen quencher is within the above range, which can provide sufficient active oxygen quencher to ensure that it is fully covered on the surface of the lithium replenishing material, thereby improving the quenching ability of the lithium replenisher on active oxygen, thereby effectively reducing the gas production of the battery and improving the safety of the battery. At the same time, it can reduce the side reaction between active oxygen and electrolyte and the consumption of electrolyte, increase the porosity of the electrode, and thus improve the rate discharge performance of the battery.

[0087] In some embodiments of the present invention, the present invention provides a positive electrode sheet, comprising the lithium supplement agent as described above or the lithium supplement agent prepared by the preparation method as described above.

[0088] The positive electrode sheet of the present invention can be prepared by conventional technical means in the field. Specifically, the above-mentioned lithium supplement agent, positive electrode active material, conductive agent, and binder can be uniformly dispersed in a solvent to obtain a positive electrode active layer slurry, and then the positive electrode active layer slurry is coated on at least one functional surface of the positive electrode current collector. After drying, the positive electrode sheet of the present invention can be obtained.

[0089] The present invention does not particularly limit the specific types of the conductive agent and the adhesive. The conductive agent, the adhesive and other components can be selected from conventional substances in the field. For example, the conductive agent can be selected from one or more of conductive carbon black, carbon nanotubes, conductive graphite, and graphene, and the adhesive can be selected from one or more of polyvinylidene fluoride (PVDF), acrylic acid-modified PVDF, polyacrylate polymers, polyimide, styrene-butadiene rubber, and styrene-propylene rubber.

[0090] The present invention does not specifically limit the coating method, and any coating method such as gravure coating, extrusion coating, spray coating, screen printing, etc. can be used to coat the positive electrode active layer slurry.

[0091] The positive electrode sheet provided by the present invention includes the above-mentioned lithium supplement agent. As the lithium supplement agent decomposes, pores are formed in situ inside the positive electrode sheet, thereby increasing the sheet porosity of the positive electrode, improving the liquid phase mass transfer capacity of the positive electrode sheet, reducing the overall polarization of the battery, improving the power performance of the battery, and at the same time reducing the gas production of the battery.

[0092] In some embodiments of the present invention, the positive electrode sheet includes a positive electrode active material, and the mass ratio of the lithium supplement to the positive electrode active material is 0.1%-3%, for example, it can be 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3% or any two thereof.

[0093] In the positive electrode sheet of the present invention, the mass ratio of the lithium supplement agent to the positive electrode active material is within the above range, which can further increase the porosity of the positive electrode sheet, enhance the rate discharge performance of the battery, reduce the gas production of the battery, and improve the safety of the battery.

[0094] In some embodiments of the present invention, the present invention provides a battery comprising the positive electrode sheet as described above. The battery has advantages corresponding to the positive electrode sheet described above, which will not be described in detail.

[0095] The battery of the present invention includes, in addition to the positive electrode sheet, a separator, a negative electrode sheet, and an electrolyte. The composition of the negative electrode sheet can refer to conventional negative electrode sheets in the art, and the separator can also be a separator commonly used in the art, such as PP film, PE film, etc.

[0096] The battery of the present invention can be prepared by conventional methods in the field. Specifically, the positive electrode sheet, the separator and the negative electrode sheet can be stacked in sequence, and then the battery core can be obtained through a lamination or winding process, and then through baking, liquid injection, formation, packaging and other processes to obtain the above-mentioned battery.

[0097] The batteries of the present application may include battery cells, battery modules, and battery packs. In some embodiments, battery cells may be assembled into a battery module, which may contain one or more battery cells, with the specific number selected by those skilled in the art based on the application and capacity of the battery module. In some embodiments, battery modules may also be assembled into a battery pack, which may contain one or more battery modules, with the specific number selected by those skilled in the art based on the application and capacity of the battery pack.

[0098] There is no particular restriction on the specific type of battery in this application. For example, from the perspective of shape, the battery includes but is not limited to square shell batteries, soft pack batteries and cylindrical batteries, etc., and this application does not impose any particular restrictions. From the perspective of the core structure, the core of the battery can be a wound core (i.e., the positive electrode sheet, the negative electrode sheet and the separator are stacked and then wound to form the core), or it can be a laminated core (i.e., multiple positive electrode sheets, negative electrode sheets and separators are stacked to form the core). The outer shell can be a hard shell (such as a steel shell, a hard plastic shell, etc.), or a soft shell (such as an aluminum plastic film, a bag-type soft shell, etc.). This application does not impose any particular restrictions.

[0099] In some embodiments of the present invention, the present invention provides an electrical device including the battery as described above. The electrical device has advantages corresponding to the above-mentioned positive electrode sheet, which will not be described in detail.

[0100] The electrical equipment of the present invention can be conventional electrical equipment in the field, such as power equipment (such as electric vehicles), electronic equipment (such as computers, mobile phones, digital cameras, printers, fax machines, etc.), wearable devices (such as watches, bracelets, VR glasses, etc.), household appliances (such as air conditioners, refrigerators, washing machines, microwave ovens, etc.), etc., without special restrictions.

[0101] The technical solution of the present invention is further described below with reference to specific embodiments.

[0102] Example 1

[0103] The preparation method of the lithium supplement agent of this embodiment comprises the following steps:

[0104] 1) The lithium-supplementing material Li5FeO4 was dispersed in N,N-dimethylformamide, and the amino-containing modifier diethylenetriamine was added. The mixture was stirred at 80°C for 8 hours. After completion of the reaction, the mixture was filtered and dried to obtain the amino-supplementing material. The molar ratio of the lithium-supplementing material Li5FeO4 to the amino-containing modifier diethylenetriamine was 1:3.

[0105] 2) Adding an amino lithium-supplementing material and diglycidyl ether to a solvent, N,N-dimethylformamide, wherein the molar ratio of the lithium-supplementing material Li5FeO4 to the diglycidyl ether of the compound containing an intermediate functional group (epoxy group) is 1:4, to obtain a first solution. The first solution is stirred at 80°C and a first reaction is carried out for 8 hours. After the reaction is completed, the solution is washed three times by centrifugation with N,N-dimethylformamide at a centrifugal speed of 8000 rpm and a centrifugal time of 10 minutes. The precipitate is dried to obtain a first intermediate.

[0106] 3) The first intermediate was added to the solvent N,N-dimethylformamide and stirred to disperse uniformly. After that, the active oxygen quencher triphenylamine was added. The molar ratio of the lithium supplement material Li5FeO4 to the active oxygen quencher triphenylamine was 1:2 to obtain a second solution. The second solution was stirred at 80°C and a second reaction was carried out for 10 hours. After the reaction was completed, the solution was centrifuged and washed three times with N,N-dimethylformamide at a speed of 8000 rpm for 10 minutes. The precipitate was dried to obtain a lithium supplement. The lithium supplement comprises a lithium supplement material and an active oxygen quencher present on at least a portion of the surface of the lithium supplement material. The lithium supplement material is grafted with a first amino group, and the active oxygen quencher comprises a second amino group, the first amino group being connected to the second amino group via an intermediate functional group. The weight proportion of the active oxygen quencher in the lithium supplement agent is 0.5%.

[0107] Soft pack full battery production

[0108] Positive electrode sheet preparation: LiFePO4 was used as the positive electrode active material. The specified amount of materials was weighed out in a mass ratio of 100:0.5:2:2 for the positive electrode active material, lithium supplement, PVDF (binder), and carbon black (conductive agent). PVDF and N-methylpyrrolidone (NMP) were first mixed and thoroughly blended. The conductive agent, positive electrode active material, and lithium supplement were then added in that order. After uniform dispersion, a positive electrode slurry with a viscosity of 3 Pa·s-9 Pa·s and a fineness of less than 25 μm was obtained. The positive electrode slurry was applied to both surfaces of an aluminum foil current collector, dried, roll-pressed, and slit to obtain the positive electrode sheet. The positive electrode sheet consists of the positive electrode active material, with a mass ratio of 0.5% for the lithium supplement to the positive electrode active material.

[0109] Preparation of negative electrode sheet: Graphite is used as the negative electrode active material, and the negative electrode active material, carbon black, styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC) are uniformly dispersed in deionized water in a mass ratio of 100:1.5:3:3. After uniform dispersion, the negative electrode slurry is obtained. The negative electrode slurry is coated on both surfaces of the copper foil current collector, and the negative electrode sheet is obtained after drying, rolling, and slitting.

[0110] Full battery assembly: The electrolyte used was a mixture of 1 mol / L LiPF6 in ethylene carbonate (EC) and diethyl carbonate (DEC) (volume ratio 1:1), and the separator was a three-layer composite membrane of polypropylene (PP), polyethylene (PE), and polypropylene (PP). In a dew-point environment, the positive electrode sheet, separator, and negative electrode sheet were assembled into a battery cell. The cell was then tab-welded and coated with aluminum-plastic film. After baking, the electrolyte was injected to prepare the battery for subsequent testing.

[0111] Example 2

[0112] The preparation method of the lithium supplement agent and the preparation method of the battery in Example 2 are basically the same as those in Example 1, except that the molar ratio of the lithium supplement material Li5FeO4 to the active oxygen quencher triphenylamine is 1:2.5, and the mass proportion of the active oxygen quencher in the lithium supplement agent is 1%.

[0113] Example 3

[0114] The preparation method of the lithium supplement agent and the preparation method of the battery in Example 3 are basically the same as those in Example 1, except that the molar ratio of the lithium supplement material Li5FeO4 to the active oxygen quencher triphenylamine is 1:3, and the mass proportion of the active oxygen quencher in the lithium supplement agent is 1.5%.

[0115] Example 4

[0116] The preparation method of the lithium supplement agent and the preparation method of the battery in Example 4 are basically the same as those in Example 1, except that the molar ratio of the lithium supplement material Li5FeO4 to the active oxygen quencher triphenylamine is 1:3.5, and the mass proportion of the active oxygen quencher in the lithium supplement agent is 2%.

[0117] Example 5

[0118] The preparation method of the lithium supplement agent and the preparation method of the battery in Example 5 are basically the same as those in Example 1, except that the molar ratio of the lithium supplement material Li5FeO4 to the active oxygen quencher triphenylamine is 1:4, and the mass proportion of the active oxygen quencher in the lithium supplement agent is 2.5%.

[0119] Example 6

[0120] The preparation method of the lithium supplement material and the preparation method of the battery in Example 6 are basically the same as those in Example 1, except that the molar ratio of the lithium supplement material Li5FeO4 to the amino-containing modifier diethylenetriamine is 1:1.5.

[0121] Example 7

[0122] The preparation method of the lithium supplement material and the preparation method of the battery in Example 7 are basically the same as those in Example 1, except that the molar ratio of the lithium supplement material Li5FeO4 to the amino-containing modifier diethylenetriamine is 1:5.

[0123] Example 8

[0124] The preparation method of the lithium replenisher and the preparation method of the battery in Example 8 are basically the same as those in Example 1, except that the molar ratio of the lithium replenisher material Li5FeO4 to the diglycidyl ether compound containing an intermediate functional group (epoxy group) is 1:1.5.

[0125] Example 9

[0126] The preparation method of the lithium replenisher and the preparation method of the battery in Example 9 are basically the same as those in Example 1, except that the molar ratio of the lithium replenisher material Li5FeO4 to the diglycidyl ether compound containing an intermediate functional group (epoxy group) is 1:5.

[0127] Example 10

[0128] The preparation method of the lithium supplement agent and the preparation method of the battery in Example 10 are basically the same as those in Example 1, except that the active oxygen quencher is changed to 2-aminoimidazole.

[0129] Example 11

[0130] The preparation method of the lithium supplement agent and the battery preparation method of Example 11 are basically the same as those of Example 1, except that the mass ratio of the positive electrode active material, the lithium supplement agent, the binder PVDF, and the conductive agent carbon black is 100:1:2:2, so that the mass ratio of the lithium supplement agent to the positive electrode active material is 1%.

[0131] Example 12

[0132] The preparation method of the lithium supplement agent and the battery preparation method of Example 12 are basically the same as those of Example 1, except that the mass ratio of the positive electrode active material, lithium supplement agent, binder PVDF, and conductive agent carbon black is 100:1.5:2:2, resulting in a mass ratio of the lithium supplement agent to the positive electrode active material of 1.5%.

[0133] Example 13

[0134] The preparation method of the lithium supplement agent and the battery preparation method of Example 13 are basically the same as those of Example 1, except that the mass ratio of the positive electrode active material, the lithium supplement agent, the binder PVDF, and the conductive agent carbon black is 100:2:2:2, resulting in a mass ratio of the lithium supplement agent to the positive electrode active material of 2%.

[0135] Example 14

[0136] The preparation method of the lithium supplement agent and the battery preparation method of Example 14 are basically the same as those of Example 1, except that the mass ratio of the positive electrode active material, the lithium supplement agent, the binder PVDF, and the conductive agent carbon black is 100:3:2:2, resulting in a mass ratio of the lithium supplement agent to the positive electrode active material of 3%.

[0137] Comparative Example 1

[0138] The lithium supplement in Comparative Example 1 is Li5FeO4, and the surface is not coated with an active oxygen quencher. The preparation method of the battery is the same as that of Example 1.

[0139] Test example:

[0140] 1. Battery interface condition: Observe the interface condition of the off-line battery: After the battery cell is off the line, discharge it at a constant current of 1C to 2.0V, let it rest for 30 minutes, then discharge it at a constant current of 0.2C to 2.0V, let it rest for 30 minutes, and then charge it at a constant current and voltage of 0.5C to 3.8V, with a cut-off current of 0.05C. In a dew-point environment, disassemble the fully charged battery cell and observe the interface condition of the negative electrode.

[0141] 2. Mass proportion of the active oxygen quencher in the lithium supplement: record the mass of the initial lithium supplement as w1. After the reaction is completed, centrifugal drying is performed to obtain the mass of the lithium supplement containing the active oxygen quencher as w2. The mass proportion wt% = (w2-w1) / w2×100%.

[0142] 3. Battery gas production test: Use a small soft-pack battery cell after formation, stick nano tape on the side of the air bag, use a needle to extract the gas in the air bag, and record the needle scale value, which is the gas production.

[0143] 4. Porosity of the positive electrode sheet: Remove the offline battery cells and disassemble them in a dew point environment. The test method can refer to the national standard GB / T21650.1-2008. Remove the middle layer of positive electrode sheets and perform a mercury intrusion test to determine the porosity.

[0144] 5. Rate performance test: Discharge at 1C constant current to 2.0V, wait for 30 minutes, then discharge at 0.2C constant current to 2.0V, wait for 30 minutes; charge at 0.5C constant current and constant voltage to 3.8V, with a cut-off current of 0.05C. Discharge at 1C constant current to 2.0V, record the cell capacity as Q1, wait for 30 minutes, then charge at 0.5C constant current and constant voltage to 3.8V, with a cut-off current of 0.05C, wait for 30 minutes, then discharge at 6C constant current to 2.0V, record the cell capacity as Q2, and calculate the 6C / 1C capacity retention rate % = Q2 / Q1×100%.

[0145] Figure 1 Schematic diagram of the interfaces of the batteries of Examples 1 to 5 and Comparative Example 1 of the present invention.

[0146] from Figure 1 It can be seen that the interfaces of the batteries of Examples 1 to 5 of the present invention and Comparative Example 1 are good, with no brown spots or abnormalities. This indicates that the addition of the active oxygen quencher to the lithium supplements of Examples 1 to 5 has no effect on the battery manufacturing process.

[0147] Figure 2 Graph showing gas production of batteries according to Examples 1 to 5 of the present invention and Comparative Example 1.

[0148] from Figure 2 It can be seen that compared with Comparative Example 1, the gas production of the batteries of Examples 1 to 5 is significantly reduced; and it can be seen from Examples 1 to 4 that as the mass proportion of the active oxygen quencher in the lithium supplement increases, the gas production decreases.

[0149] Figure 3 Schematic diagram of the interfaces of the batteries of Examples 1 and 11 to 14 of the present invention.

[0150] from Figure 3 It can be seen that the interfaces of the batteries of Examples 1, 11 to 14 of the present invention are good, without brown spots or abnormalities, indicating that the addition of the active oxygen quencher to the lithium supplements of Examples 1, 11 to 14 has no effect on the battery manufacturing process.

[0151] Figure 4 This is a porosity diagram of the positive electrode sheets of Examples 1 and 11 to 14 of the present invention.

[0152] from Figure 4 It can be seen that in the positive electrode sheets of Examples 1 and 11 to 14 of the present invention, as the mass percentage of the lithium supplement agent increases, the porosity of the positive electrode sheet increases.

[0153] Table 1

[0154]

[0155] As shown in Table 1, compared to the comparative example, the lithium supplement provided by the present invention contains an active oxygen quencher on at least a portion of the surface of the lithium supplement material. This quenches the generated active oxygen, reducing battery gas production, which in turn reduces the risk of battery expansion. It also reduces side reactions between active oxygen and the electrolyte, as well as electrolyte consumption. Furthermore, it increases the porosity of the electrode, thereby improving the battery's rate discharge performance. Furthermore, the active oxygen quencher is linked to the lithium supplement material via a first amino group, enhancing the chemical stability of the lithium supplement.

[0156] It can be seen from Examples 1-3 that as the mass proportion of the active oxygen quencher in the lithium supplement increases, the electrode porosity gradually increases, the battery rate performance gradually improves, and the gas production gradually decreases.

[0157] It can be seen from Example 1 and Examples 11-14 that as the mass ratio of the lithium supplement agent to the positive electrode active material increases, the electrode porosity gradually increases and the battery rate performance gradually improves.

[0158] Finally, it should be noted that those skilled in the art will readily identify other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art not disclosed herein. The present invention is not limited to the precise structure described above and illustrated in the accompanying drawings, and various modifications and variations may be made without departing from the scope thereof. The scope of the present invention is limited solely by the appended claims.

Claims

1. A lithium supplement, characterized in that: The invention comprises a lithium supplement material and an active oxygen quencher present on at least a portion of the surface of the lithium supplement material; The lithium supplement material is grafted with a first amino group; The active oxygen quencher is connected to the lithium supplement material via the first amino group; The first amino group is connected to the active oxygen quencher through an intermediate functional group.

2. The lithium supplement according to claim 1, characterized in that The active oxygen quencher includes a second amino group, and the first amino group is connected to the second amino group through the intermediate functional group.

3. The lithium supplement according to claim 1, characterized in that The active oxygen quencher includes at least one of triphenylamine, 2-aminoimidazole, 1-(3-aminopropyl)imidazole, 4-amino-1,2,4-triazole, chitosan, dopamine and derivatives thereof.

4. The lithium supplement according to claim 1, characterized in that The mass proportion of the active oxygen quencher in the lithium supplement is 0.5%-2.5%.

5. The lithium supplement according to claim 1, characterized in that The intermediate functional group includes an ether group.

6. The lithium supplement according to any one of claims 1 to 5, characterized in that: The lithium supplement material is Li x M y O z , wherein M includes at least one of C, Fe, Co, Ni, Mn and Cr, x≥2, y≥1, z≥1.

7. The lithium supplement according to claim 6, characterized in that 2≤x≤7, 1≤y≤4, 1≤z≤6.

8. The lithium supplement according to claim 7, characterized in that The lithium supplement material includes at least one of Li5FeO4, Li2NiO2, Li2C2O4, and Li6CoO4.

9. A method for preparing the lithium supplement according to any one of claims 1 to 8, characterized in that: The following steps are involved: 1) performing an amination treatment on the lithium-supplementing material to obtain an amination lithium-supplementing material; 2) Grafting the active oxygen quencher onto the amino lithium-supplementing material to obtain the lithium-supplementing agent.

10. The method for preparing a lithium supplement according to claim 9, wherein: The step of grafting an active oxygen quencher onto the aminated lithium-supplementing material to obtain the lithium-supplementing agent comprises: Performing a first reaction on a first system including the amino lithium-supplementing material and a compound containing an intermediate functional group to obtain a first intermediate; A second reaction is performed on a second system including the first intermediate and the active oxygen quencher to obtain the lithium supplement agent.

11. The method for preparing a lithium supplement according to claim 10, wherein: The active oxygen quencher includes a second amino group.

12. The method for preparing a lithium supplement according to claim 9, wherein: performing an amination treatment on the lithium supplement material using an amino-containing modifier; The amino-containing modifier includes at least one of diethylenetriamine, ethylenediaminetetraacetic acid, carbamic acid and glycine.

13. The method for preparing a lithium supplement according to claim 10, wherein: The compound containing an intermediate functional group includes a compound containing an epoxy group, and the compound containing an epoxy group includes at least one of diglycidyl ether, ethylene glycol diglycidyl ether, and 1,4-butanediol diglycidyl ether.

14. The method for preparing a lithium supplement according to claim 10 or 13, wherein: The molar ratio of the lithium-supplementing material to the compound containing the intermediate functional group is 1:(1.5-5).

15. The method for preparing a lithium supplement according to claim 12, wherein: The molar ratio of the lithium-supplementing material to the amino-containing modifier is 1:(1.5-5).

16. The method for preparing a lithium supplement according to any one of claims 9 to 13, wherein: The molar ratio of the lithium replenishing material to the active oxygen quencher is 1:(2-4).

17. A positive electrode sheet, characterized in that: The lithium supplement comprises the lithium supplement according to any one of claims 1 to 8 or the lithium supplement prepared by the preparation method according to any one of claims 9 to 16.

18. The positive electrode sheet according to claim 17, characterized in that: The positive electrode sheet includes a positive electrode active material, and the mass ratio of the lithium supplement agent to the positive electrode active material is 0.1%-3%.

19. A battery, characterized in that: Including the positive electrode sheet according to claim 17 or 18.

20. An electrical device, characterized in that: Including the battery according to claim 19.

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