Lithium supplement agent and preparation method thereof, positive plate, battery and electric equipment

Abstract

The invention provides a lithium supplement agent and a preparation method thereof, a positive plate, a battery and electric equipment. The lithium supplement agent provided by the invention comprises a lithium supplement material and an active oxygen quencher existing on at least part of the surface of the lithium supplement material, the active lithium supplement material is grafted with a first amino group; the active oxygen quencher is connected with the lithium supplementing material through the first amino group. The lithium supplement agent provided by the invention has the active oxygen quencher on at least part of the surface of the lithium supplement material, so that the generated active oxygen can be quenched, the gas production rate of the battery can be reduced, namely the risk of battery expansion can be reduced, the side reaction of the active oxygen and electrolyte and the consumption of the electrolyte can be reduced, and meanwhile, the porosity of a pole piece can be improved, and the service life of the battery can be prolonged. Therefore, the rate discharge performance of the battery is improved.

Description

Technical Field

[0001] The 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] In order to compensate for the loss of active lithium caused by the formation of SEI film during the first charge of the battery, a lithium supplement is usually added to the battery slurry to offset the active lithium consumption and thus increase the cycle life of the battery. However, the introduction of lithium supplements increases the risk of active oxygen release, causing the battery to swell with gas. Summary of the invention

[0003] The main purpose of the present invention is to provide a lithium supplement, 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, so the positive electrode sheet has a high porosity and is 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, so that the gas production of the battery is low, the porosity of the positive electrode sheet is high, and the rate discharge performance of the battery is improved.

[0007] The present invention also provides an electrical device, comprising the above-mentioned battery, so 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 supplement 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 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] As described above, the mass proportion of the active oxygen quencher in the lithium supplement is 0.5%-2.5%.

[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] As mentioned above, the lithium supplement material includes Li 5 FeO 4 , Li 2 NiO 2 , Li 2 C 2 O 4 , Li 6 CoO 4 At least one of .

[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 aminated lithium replenishing material to obtain the lithium replenishing agent.

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

[0022] Performing a first reaction on a first system including the aminated 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] In the preparation method as described above, the active oxygen quencher includes a second amino group.

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

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

[0027] In the preparation method as described above, the compound containing the 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 as described above, the molar ratio of the lithium supplement material to the compound containing the intermediate functional group is 1:(1.5-5).

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

[0030] In the preparation method as 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 comprises 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 has an active oxygen quencher on at least part of the surface of the lithium supplement material, which can quench the generated active oxygen, reduce the gas production of the battery, that is, reduce the risk of battery expansion, and reduce the side reaction between active oxygen and electrolyte and the consumption of electrolyte. At the same time, the porosity of the pole piece can be improved, thereby improving the rate discharge performance of the battery. In addition, the active oxygen quencher is connected to the lithium supplement material through the first amino group, which can improve the chemical stability of the lithium supplement. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order 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, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0037] Figure 1 The diagram is an interface diagram of the batteries of Examples 1 to 5 of the present invention and Comparative Example 1;

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

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

[0040] Figure 4 The porosity diagram 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] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are 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 creative work are 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 attenuation and reduced life due to loss of active lithium remain to be solved. Researchers have proposed lithium replenishment technology to make up for the loss of active lithium. However, reactive oxygen species will be generated as the lithium replenishment material decomposes. 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 poses two major problems. First, reactive oxygen species may be released in the form of oxygen, causing an increase in internal pressure in the battery, which can cause battery swelling. This physical deformation not only affects the structural integrity of the battery, but may also lead to safety hazards such as battery leakage or explosion. Second, reactive oxygen species react with the electrolyte, leading to electrolyte consumption. This reaction not only reduces the effectiveness of the electrolyte, but may also generate unstable byproducts, further affecting the electrochemical performance and cycle life of the battery.

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

[0046] Based on this, in the first aspect, the present invention provides a lithium supplement agent, including 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 of the present invention can quench active oxygen, reduce the gas production of the battery, and at the same time, can improve the porosity of the pole piece, thereby improving the rate discharge performance of the battery. This is because, when the lithium supplement 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. And it can reduce the side reaction between active oxygen and the electrolyte, thereby reducing the adverse effects of side reactions on the battery life while replenishing active lithium, extending the service life of the battery, and also reducing the consumption of the electrolyte and maintaining the stability of the electrolyte. At the same time, after the lithium supplement is decomposed, the porosity of the pole piece can be improved. The nitrogen atom in the first amino group in the lithium supplement has a high electron density and can form hydrogen bonds with the solvent molecules in the electrolyte, which can enhance the wettability of the electrolyte, strengthen the liquid phase mass transfer capacity of the pole piece, reduce the overall polarization of the battery, and improve the uniformity of the electrode's lithium insertion and extraction, thereby improving the rate discharge performance of the battery. 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 usually has high stability and can achieve stable chemical bonding, making the structure more solid and stable, not prone to dissociation, and having high chemical stability.

[0049] Therefore, the lithium supplement provided by the present invention has an active oxygen quencher on at least part of the surface of the lithium supplement material, which can quench the generated active oxygen, reduce the gas production of the battery, that is, reduce the risk of battery expansion, and reduce the side reaction between active oxygen and electrolyte and the consumption of electrolyte. At the same time, the porosity of the pole piece can be improved, thereby improving the rate discharge performance of the battery. In addition, the active oxygen quencher is connected to the lithium supplement material through the first amino group, which can improve 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 agent.

[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 reaction between active oxygen and electrolyte and the consumption of electrolyte, thereby improving the cycle life and capacity retention rate 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 reaction of active oxygen with the electrolyte and the consumption of the electrolyte, thereby improving the cycle life and capacity retention rate of the battery.

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

[0057] In the present invention, an ether group is used as an intermediate functional group. The ether group has high molecular flexibility and can be used as a bridge to connect different chemical groups. The ether group has good chemical stability and can remain stable in the battery working environment. It is not easy to decompose, which is conducive to the connection between the lithium supplement material and the active oxygen quencher. At the same time, the stability and inertness of the ether group can prevent the active oxygen quencher from being freed, thereby improving the overall stability and safety of the battery.

[0058] In some embodiments of the present invention, the lithium supplement material is Li x My 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] Exemplarily, 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 in 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 Li 5 FeO 4 , Li 2 NiO 2 , Li 2 C 2 O 4 , Li 6 CoO 4 At least one of the above 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 supplement material to obtain an amination lithium supplement material;

[0065] 2) Grafting an active oxygen quencher onto the amino lithium-supplementing material to obtain a lithium-supplementing 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 supplement material is subjected to an amino treatment, and then the active oxygen quencher is grafted onto the surface of the lithium supplement 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 active oxygen quenchers on the surface of aminated lithium-supplementing materials can enhance the active oxygen quenching ability of lithium-supplementing materials, reduce the damage of active oxygen to batteries, reduce the gas production of batteries, and improve the safety of batteries.

[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. An active oxygen quencher is grafted on the surface of the lithium supplement material to obtain a lithium supplement agent with the active oxygen quencher grafted on the surface, which can quench the active oxygen generated when the lithium supplement agent decomposes, reduce the gas production of the battery, that is, reduce the risk of battery expansion, and reduce the side reaction of active oxygen with the electrolyte and the consumption of the electrolyte. At the same time, the porosity of the pole piece can be improved.

[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 an active oxygen quencher to obtain a lithium-supplementing agent.

[0071] In specific implementation, the aminated 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 stirred and reacted at a first temperature for a first time, and 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, and after the reaction is completed, a second centrifugal washing is performed at least 3 times with the same reaction solvent, and the precipitate is dried to obtain a lithium supplement agent grafted with an active oxygen quencher.

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

[0074] In the first reaction of the present invention, the aminated lithium supplement material reacts with a compound containing an intermediate functional group to form a stable first intermediate. This step ensures the effective combination of the intermediate functional group with the first amino group in the lithium supplement material, and provides an active platform for the subsequent grafting reaction. In the second reaction, the first intermediate reacts with the active oxygen quencher, so that the first amino group is connected to the active oxygen quencher through the intermediate functional group to form the final lithium supplement. Through this step-by-step method, the grafting efficiency of the active oxygen quencher can be improved to ensure that it is evenly distributed on the surface of the material.

[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 aminoacetic acid.

[0077] The preparation method of the present invention can disperse the lithium supplement material in a reaction solvent, add an amino-containing modifier, stir the reaction at a third temperature for a third time, filter and dry after the reaction is completed to obtain an amino lithium supplement material. The reaction solvent can be selected from at least one of N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, dimethylacetamide, isophorone, etc. The third temperature can be 80°C-100°C, and the third time can be 10h-12h.

[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 supplement 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 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.

[0080] The types of the epoxy-containing compounds are within the above range, have high reactivity, and can react quickly with the amino groups on the surface of the lithium supplementing material to form stable chemical bonds.

[0081] In some embodiments, the molar ratio of the lithium supplement material to the compound containing the intermediate functional group 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.

[0082] The molar ratio of the lithium supplement 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 supplement 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 supplement material to the amino-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 of them.

[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 subsequent grafting reactions.

[0085] In some embodiments, the molar ratio of the lithium supplement material to the active oxygen quencher is 1:(2-4), for example, it can be 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 art. 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 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 materials 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 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, spraying, 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. Along with the decomposition of the lithium supplement agent, pores are formed in situ inside the positive electrode sheet, which increases the sheet porosity of the positive electrode, improves the liquid phase mass transfer capacity of the positive electrode sheet, reduces the overall polarization of the battery, improves the power performance of the battery, and can reduce 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, including the positive electrode sheet as described above. The battery has the advantages corresponding to the positive electrode sheet described above, which will not be described in detail.

[0095] The battery of the present invention includes a separator, a negative electrode and an electrolyte in addition to a positive electrode sheet. 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 conventionally used in the art, such as a PP film, a PE film, etc.

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

[0097] The battery of the present application may include a battery cell form, a battery module form and a battery pack form. In some embodiments, the battery cells can be assembled into a battery module, and the number of battery cells contained in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module. In some embodiments, the battery modules can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0098] There is no special 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 special restrictions. From the perspective of the pole core structure, the pole core of the battery can be a wound pole core (that is, the positive pole sheet, the negative pole sheet and the separator are stacked and arranged, and then the pole core is formed by a winding process), or it can be a laminated pole core (that is, multiple positive pole sheets, negative pole sheets and separators are stacked to form a pole core). The outer shell can be a hard shell (such as a steel shell, a hard plastic shell, etc.), or it can be a soft shell (such as an aluminum-plastic film, a bag-type soft shell, etc.). This application does not impose any special 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 art, 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 in conjunction with specific embodiments.

[0102] Example 1

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

[0104] 1) Lithium replenishing material Li 5 FeO 4 Dispersed in the solvent N,N-dimethylformamide, and then added with the amino-containing modifier diethylenetriamine, stirred at 80°C for 8 hours, filtered and dried after the reaction, to obtain the amino lithium supplement material. 5 FeO 4 The molar ratio of the amino-containing modifier diethylenetriamine is 1:3.

[0105] 2) Add the aminated lithium supplement material and diglycidyl ether into the solvent N,N-dimethylformamide, and the lithium supplement material Li 5 FeO 4 The molar ratio of the diglycidyl ether of the compound containing the intermediate functional group (epoxy group) is 1:4 to obtain a first solution, and the first solution is stirred at 80°C for a first reaction for 8 hours. After the reaction is completed, it is centrifuged and washed three times with N,N-dimethylformamide, wherein the centrifugal speed is 8000rpm and the centrifugal time is 10 minutes. The precipitate is dried to obtain a first intermediate.

[0106] 3) Add the first intermediate into the solvent N,N-dimethylformamide, stir and disperse evenly, then add the active oxygen quencher triphenylamine and the lithium supplement material Li 5 FeO 4 The molar ratio of triphenylamine to the active oxygen quencher is 1:2 to obtain a second solution, and the second solution is stirred at 80°C for a second reaction for 10 hours. After the reaction is completed, it is centrifuged and washed three times with N,N-dimethylformamide, wherein the centrifugal speed is 8000rpm and the centrifugal time is 10 minutes. The precipitate is dried to obtain a lithium supplement. The lithium supplement includes a lithium supplement material and an active oxygen quencher present on at least part of the surface of the lithium supplement material. The lithium supplement material is grafted with a first amino group, and the active oxygen quencher includes a second amino group. The first amino group is connected to the second amino group through an intermediate functional group, and the mass proportion of the active oxygen quencher in the lithium supplement is 0.5%.

[0107] Soft pack battery production

[0108] Positive electrode preparation: Take LiFePO 4 As the positive electrode active material, the specified amount of material is weighed out according to the mass ratio of positive electrode active material, lithium supplement agent, binder PVDF, and conductive agent carbon black of 100:0.5:2:2. PVDF is first mixed with N-methylpyrrolidone (NMP), and then the conductive agent, positive electrode active material and lithium supplement agent are added in sequence. After uniform dispersion, a positive electrode slurry with a viscosity of 3Pa·s-9Pa·s and a fineness of less than 25μm is obtained; the positive electrode slurry is coated on both surfaces of the aluminum foil current collector, and the positive electrode sheet is obtained after drying, rolling and slitting. The positive electrode sheet includes the positive electrode active material, and the mass ratio of the lithium supplement agent to the positive electrode active material is 0.5%.

[0109] Preparation of negative electrode sheet: Take graphite as the negative electrode active material, and evenly disperse it in deionized water in a mass ratio of 100:1.5:3:3 among the negative electrode active material, carbon black, styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC). After even dispersion, a negative electrode slurry is obtained, and the negative electrode slurry is coated on both surfaces of the copper foil current collector. After drying, rolling and slitting, a negative electrode sheet is obtained.

[0110] Full battery assembly: 1 mol / L LiPF is used as the electrolyte 6 The electrolyte is a mixed electrolyte of ethylene carbonate (EC) + diethyl carbonate (DEC) (volume ratio 1:1), and the separator is a three-layer composite separator of polypropylene (PP) / polyethylene (PE) / polypropylene (PP). In a dew point environment, the positive electrode sheet, separator and negative electrode sheet are assembled into a battery cell, and the battery cell is subjected to the process of ear welding and aluminum-plastic film wrapping. After baking, the electrolyte is injected to prepare a 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 lithium supplement material Li 5 FeO 4 The molar ratio of the active oxygen quencher triphenylamine to the lithium supplement is 1:2.5, and the mass proportion of the active oxygen quencher in the lithium supplement 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 lithium supplement material Li 5 FeO 4 The molar ratio of the active oxygen quencher triphenylamine to the lithium supplement is 1:3, and the mass proportion of the active oxygen quencher in the lithium supplement 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 lithium supplement material Li 5 FeO 4 The molar ratio of the active oxygen quencher triphenylamine to the lithium supplement is 1:3.5, and the mass proportion of the active oxygen quencher in the lithium supplement 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 lithium supplement material Li 5 FeO 4 The molar ratio of the active oxygen quencher triphenylamine to the lithium supplement is 1:4, and the mass proportion of the active oxygen quencher in the lithium supplement is 2.5%.

[0119] Example 6

[0120] The preparation method of the lithium supplement agent and the preparation method of the battery in Example 6 are basically the same as those in Example 1, except that the lithium supplement material Li 5 FeO 4 The molar ratio of the amino-containing modifier diethylenetriamine is 1:1.5.

[0121] Example 7

[0122] The preparation method of the lithium supplement agent and the preparation method of the battery in Example 7 are basically the same as those in Example 1, except that the lithium supplement material Li 5 FeO 4 The molar ratio of the amino-containing modifier diethylenetriamine is 1:5.

[0123] Example 8

[0124] The preparation method of the lithium supplement agent and the preparation method of the battery in Example 8 are basically the same as those in Example 1, except that the lithium supplement material Li 5 FeO 4 The molar ratio of the diglycidyl ether to the compound containing the intermediate functional group (epoxy group) is 1:1.5.

[0125] Example 9

[0126] The preparation method of the lithium supplement agent and the preparation method of the battery in Example 9 are basically the same as those in Example 1, except that the lithium supplement material Li 5 FeO 4 The molar ratio of the diglycidyl ether to the compound containing the 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] Embodiment 11

[0130] The preparation method of the lithium supplement agent and the preparation method of the battery in Example 11 are basically the same as those in 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 preparation method of the battery in Example 12 are basically the same as those in 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 100:1.5:2:2, so that the mass ratio of the lithium supplement agent to the positive electrode active material is 1.5%.

[0133] Embodiment 13

[0134] The preparation method of the lithium supplement agent and the preparation method of the battery in Example 13 are basically the same as those in 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, so that the mass ratio of the lithium supplement agent to the positive electrode active material is 2%.

[0135] Embodiment 14

[0136] The preparation method of the lithium supplement agent and the preparation method of the battery in Example 14 are basically the same as those in 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, so that the mass ratio of the lithium supplement agent to the positive electrode active material is 3%.

[0137] Comparative Example 1

[0138] The lithium supplement agent of Comparative Example 1 is Li 5 FeO 4 The preparation method of the battery is the same as that of Example 1.

[0139] Test example:

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

[0141] 2. The mass proportion of the active oxygen quencher in the lithium supplement: the mass of the initial lithium supplement is recorded as w1. After the reaction is completed, the mass of the lithium supplement containing the active oxygen quencher obtained by centrifugal drying is w2, and 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 positive electrode sheet: Take off the offline battery cell and disassemble it in a dew point environment. The test method can refer to the national standard GB / T21650.1-2008, take out the middle layer of positive electrode sheet and conduct mercury injection test to obtain the porosity.

[0144] 5. Rate performance test: Discharge at 1C constant current to 2.0V, leave for 30 minutes, then discharge at 0.2C constant current to 2.0V, leave 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, leave for 30 minutes, charge at 0.5C constant current and constant voltage to 3.8V, with a cut-off current of 0.05C, leave 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 This is a diagram of the interface conditions of the batteries of Examples 1 to 5 of the present invention and Comparative Example 1.

[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, without brown spots or abnormalities, which indicates that the addition of active oxygen quencher to the lithium supplement of Examples 1 to 5 has no effect on the battery manufacturing process.

[0147] Figure 2 This is a graph of gas production of the batteries of 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 is lower.

[0149] Figure 3 This is a diagram of the interface conditions 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, which indicates that the addition of active oxygen quencher to the lithium supplement 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, 11, and 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 can be seen from Table 1, compared with the comparative example, the lithium supplement provided by the present invention has an active oxygen quencher on at least part of the surface of the lithium supplement material, which can quench the active oxygen generated, reduce the gas production of the battery, that is, reduce the risk of battery expansion, and reduce the side reaction between active oxygen and electrolyte and the consumption of electrolyte. At the same time, the porosity of the pole piece can be improved, thereby improving the rate discharge performance of the battery. In addition, the active oxygen quencher is connected to the lithium supplement material through the first amino group, which can improve 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 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 conceive of 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, which follow the general principles of the present invention and include common knowledge or customary technical means in the art not disclosed by the present invention, are not limited to the precise structure described above and shown in the drawings, and may be modified and changed in various ways without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A lithium supplement, characterized in that: It 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 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.

2. The lithium supplement according to claim 1, characterized in that: The first amino group is connected to the active oxygen quencher via an intermediate functional group.

3. The lithium supplement according to claim 2, 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.

4. 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.

5. 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%.

6. The lithium supplement according to claim 2, characterized in that: The intermediate functional group includes an ether group.

7. The lithium supplement according to any one of claims 1 to 6, 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.

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

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

10. A method for preparing the lithium supplement according to any one of claims 1 to 9, 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 aminated lithium replenishing material to obtain the lithium replenishing agent.

11. The method for preparing a lithium supplement according to claim 10, characterized in that: 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 aminated 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.

12. The method for preparing a lithium supplement according to claim 11, characterized in that: The active oxygen quencher includes a second amino group.

13. The method for preparing a lithium supplement according to claim 10, characterized in that: Using an amino-containing modifier to perform an amination treatment on the lithium supplement material; The amino-containing modifier includes at least one of diethylenetriamine, ethylenediaminetetraacetic acid, carbamic acid and aminoacetic acid.

14. The method for preparing a lithium supplement according to claim 11, characterized in that: 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.

15. The method for preparing a lithium supplement according to claim 11 or 14, characterized in that: The molar ratio of the lithium supplement material to the compound containing the intermediate functional group is 1:(1.5-5).

16. The method for preparing a lithium supplement according to claim 13, characterized in that: The molar ratio of the lithium supplement material to the amino-containing modifier is 1:(1.5-5).

17. The method for preparing a lithium supplement according to any one of claims 10 to 14, characterized in that: The molar ratio of the lithium supplement material to the active oxygen quencher is 1:(2-4).

18. A positive electrode sheet, characterized in that: The invention comprises the lithium supplement agent according to any one of claims 1 to 9 or the lithium supplement agent prepared by the preparation method according to any one of claims 10 to 17.

19. The positive electrode sheet according to claim 18, 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%.

20. A battery, characterized in that: Including the positive electrode sheet as described in claim 18 or 19.

21. An electrical equipment, characterized in that: Comprising the battery of claim 20.

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