Composite lithium supplement agent and preparation method thereof, battery, battery pack and electric equipment

Abstract

The invention provides a composite lithium supplement agent and a preparation method thereof, a battery, a battery pack and electric equipment. The composite lithium supplement agent comprises titanium dioxide with a three-dimensional network structure and a coating layer coating at least part of the surface of the titanium dioxide, and the coating layer comprises a lithium supplement agent. According to the composite lithium supplement agent, the three-dimensional network structure is integrally formed through the titanium dioxide of the three-dimensional network structure and the coating layer, the composite lithium supplement agent integrally forming the three-dimensional network structure has a large surface area and rich pore structures, and the ion transmission efficiency can be improved through the design of the large surface area and the rich pore structures; and the three-dimensional network structure can well uniformly disperse active lithium in the lithium supplement agent, so that local lithium source enrichment is reduced, the capacity retention ratio of the battery is improved, and the internal resistance is reduced.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a composite lithium supplement and a preparation method thereof, a battery, a battery pack, and electrical equipment. Background Art

[0002] During the initial charge of a lithium-ion battery, a solid electrolyte interphase (SEI) forms on the negative electrode surface. This SEI converts the active lithium inside the battery into lithium carbonate, lithium fluoride, and alkyl lithium, resulting in lithium loss in the lithium-rich positive electrode.

[0003] Generally, lithium replenishment can be used to add new lithium sources to the electrode material to compensate for the loss of active lithium caused by the formation of the solid electrolyte interface film during the first cycle. However, the lithium replenisher may not be evenly distributed on the electrode surface, which may lead to excessive lithium abundance in some areas of the electrode, resulting in an imbalance in current density distribution, and further making the lithium replenisher unable to effectively improve the battery's capacity retention rate and reduce the battery's internal resistance. Summary of the Invention

[0004] The technical problem to be solved by the present application is to provide a composite lithium supplement agent that can supplement lithium in lithium-ion batteries, effectively improve the capacity retention rate of the battery, and reduce internal resistance.

[0005] In order to solve the above problems, an embodiment of the present application provides a composite lithium supplement, which includes titanium dioxide having a three-dimensional network structure and a coating layer coated on at least a portion of the surface of the titanium dioxide, wherein the coating layer includes a lithium supplement.

[0006] Optionally, the titanium dioxide is a nanobelt structure.

[0007] Optionally, the lithium supplement includes at least one of lithium-rich lithium cobaltate, lithium-rich lithium nickelate, lithium-rich lithium ferrite, lithium oxide, lithium peroxide, lithium sulfide, lithium nitride, lithium carbonate, and lithium oxalate.

[0008] Optionally, the lithium supplement is lithium-rich lithium ferrite.

[0009] Optionally, the coating layer further includes a binder.

[0010] Optionally, the binder includes a first binder and / or a second binder; the first binder includes at least one of polyacrylic acid, polyvinyl pyrrolidone, epoxy resin, polyurethane, polyvinylidene fluoride and polyvinyl alcohol; the second binder includes at least one of lithium carboxymethyl cellulose, lithium polyacrylate and lithium polystyrene sulfonate.

[0011] Optionally, the mass ratio of the titanium dioxide to the lithium supplement agent is (5-20):(1-2).

[0012] Optionally, the mass ratio of the lithium supplement agent to the binder is (1-2):(3-4).

[0013] Optionally, the binder includes a first binder and a second binder, and the mass ratio of the first binder to the second binder is (1-5):(1-5).

[0014] The present invention also provides a method for preparing a composite lithium supplement, the method comprising:

[0015] mixing the lithium supplement agent and the titanium dioxide having a three-dimensional network structure to obtain a mixture;

[0016] performing an aging treatment on the mixture to obtain an aging product in which the lithium supplementing agent is coated on at least a portion of the surface of the titanium dioxide;

[0017] The aged product is calcined to obtain the composite lithium supplement agent.

[0018] Optionally, the step of mixing the lithium supplement agent and the titanium dioxide having a three-dimensional network structure to obtain a mixture comprises:

[0019] The lithium supplement agent, the titanium dioxide having a three-dimensional network structure and a binder are mixed to obtain a mixture.

[0020] Optionally, the mass ratio of the titanium dioxide having a three-dimensional network structure, the lithium supplement agent and the binder is (5-20):(1-2):(3-4).

[0021] Optionally, before the step of aging the mixture to obtain an aged product in which the lithium supplement agent is coated on at least a portion of the surface of the titanium dioxide, the process further comprises:

[0022] A basic solvent is added to the mixture, wherein the basic solvent comprises anhydrous ethanol and aqueous ammonia.

[0023] Optionally, the volume ratio between the anhydrous ethanol and the ammonia water is (5-15):1.

[0024] Optionally, the calcination temperature is 200° C. to 800° C., and the calcination time is 2 h to 8 h.

[0025] Optionally, the method for preparing the titanium dioxide having a three-dimensional network structure comprises:

[0026] mixing a titanium source, a pH adjuster, and a solvent to obtain a first mixture;

[0027] mixing the first mixture and an acid to obtain a second mixture;

[0028] The second mixture is subjected to heat preservation treatment and then solid-liquid separation to obtain the titanium dioxide having a three-dimensional network structure.

[0029] Optionally, at least one of the following conditions is met:

[0030] The titanium source includes at least one of titanium tetrachloride, titanium sulfate, titanyl sulfate, sodium hydrogen titanate, tetrabutyl titanate, isopropyl titanate, and ethyl titanate;

[0031] The pH regulator includes at least one of ammonia water, urea, sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate;

[0032] The solvent includes deionized water;

[0033] The acid includes at least one of hydrofluoric acid, hydrochloric acid, sulfuric acid, nitric acid, oxalic acid, tartaric acid and citric acid.

[0034] Optionally, the weight ratio of the titanium source to the pH regulator is (1-100):(1-60), and / or the molar ratio of the titanium element in the titanium source to the hydrogen element in the acid is 0.35-0.5.

[0035] Optionally, the heat preservation treatment satisfies at least one of the following conditions:

[0036] The temperature of the heat preservation treatment is 20°C to 200°C;

[0037] The heat preservation treatment time is 4h to 20h.

[0038] The embodiments of the present application further provide a battery, comprising a positive electrode sheet, wherein the positive electrode sheet comprises the composite lithium supplement described in the embodiments of the present application, or the composite lithium supplement prepared by the preparation method described in the embodiments of the present application.

[0039] An embodiment of the present application further provides a battery pack, which includes the battery described in the embodiment of the present application.

[0040] An embodiment of the present application further provides an electrical device, which includes the battery described in the embodiment of the present application or the battery pack described in the embodiment of the present application.

[0041] Compared with the prior art, this application has the following advantages:

[0042] The composite lithium supplement provided by the embodiment of the present application includes titanium dioxide with a three-dimensional network structure, and a coating layer coated on at least a portion of the surface of the titanium dioxide, wherein the coating layer includes a lithium supplement. The composite lithium supplement forms a three-dimensional network structure through the titanium dioxide with a three-dimensional network structure and the coating layer as a whole. The composite lithium supplement that forms a three-dimensional network structure as a whole has a large surface area and a rich pore structure. The design of a large surface area and a rich pore structure can improve the transmission efficiency of ions, and the three-dimensional network structure can better disperse the active lithium in the lithium supplement, reduce the occurrence of local lithium source enrichment, thereby improving the capacity retention rate of the battery and reducing the internal resistance. At the same time, the composite lithium supplement obtained can have good moisture resistance, is not easy to react with water in the air, and can still have a good capacity retention rate in a high humidity environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 Schematic diagram of the structure of a composite lithium supplement provided in an embodiment of the present application.

[0044] 1-Titanium dioxide; 2-Coating layer. DETAILED DESCRIPTION

[0045] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0046] An embodiment of the present application provides a composite lithium supplement, which includes titanium dioxide having a three-dimensional network structure and a coating layer coated on at least a portion of the surface of the titanium dioxide, wherein the coating layer includes the lithium supplement.

[0047] Specifically, in embodiments of the present application, a composite lithium replenisher can be added to the positive electrode of the battery to compensate for the irreversible loss of active lithium caused by the growth of a solid electrolyte interface film at the negative electrode, thereby improving the first-cycle coulombic efficiency, the actual output energy density, and long-term cycling stability. Furthermore, to prevent the composite lithium replenisher from causing localized lithium source enrichment, which can lead to safety issues such as lithium deposition and short circuits, the composite lithium replenisher in embodiments of the present application can be titanium dioxide with a three-dimensional network structure, with a coating layer covering at least a portion of the surface of the titanium dioxide, the coating layer comprising the lithium replenisher.

[0048] The composite lithium supplement agent forms a three-dimensional network structure through titanium dioxide having a three-dimensional network structure and the coating layer as a whole, and the three-dimensional network structure of titanium dioxide provides an embedding space for the lithium supplement agent in the coating layer, so that titanium dioxide and the coating layer as a whole also form a three-dimensional network structure. The three-dimensional network structure of the composite lithium supplement agent can have a large surface area and a rich pore structure. On the one hand, it can improve the transmission efficiency of lithium ions in the positive electrode sheet. On the other hand, it can provide space for the distribution of the lithium supplement agent, so that the lithium supplement agent can be evenly distributed on the surface of titanium dioxide, thereby effectively avoiding the occurrence of local lithium source enrichment. The lithium ions in the spatially uniformly distributed lithium supplement agent can be smoothly removed from the lithium supplement agent and quickly embedded in the negative electrode lattice gap to provide a quick channel, which can effectively make up for the active lithium ions consumed by the negative electrode to form a solid electrolyte interface film. Therefore, the composite lithium supplement agent provided in the embodiment of the present application can effectively improve the capacity retention rate of the battery and reduce the internal resistance.

[0049] At the same time, the overall three-dimensional network structure of the composite lithium supplement can provide redundant space to a certain extent, which is beneficial to the volume stress caused by the gas that may be generated during the charging and discharging process, and effectively improves the overall safety of the battery.

[0050] As a specific example of the present invention, Figure 1 Schematic diagram of the structure of a composite lithium supplement provided in an embodiment of the present application, wherein the composite lithium supplement comprises titanium dioxide 1 having a three-dimensional network structure, and a coating layer 2 coated on at least a portion of the surface of the titanium dioxide 1, wherein the coating layer 2 comprises a lithium supplement.

[0051] In one embodiment of the present application, titanium dioxide can be a nanobelt structure. It can be a nanomaterial with a ribbon structure, which can provide a higher specific surface area and provide more space for the distribution of the lithium supplement. At the same time, the nanobelt structure can provide a channel for directional transmission of electrons, which can show better electron transmission efficiency, so that the composite lithium supplement can provide better electrochemical performance. Titanium dioxide with a three-dimensional network structure can be obtained by forming an array of titanium dioxide with a nanobelt structure. Thus, the coating layer can be embedded in the titanium dioxide nanobelt array structure to form a composite lithium supplement with an overall structure of a three-dimensional network structure.

[0052] In one embodiment of the present application, a lithium supplement can be used to provide additional active lithium ions for the battery. The lithium supplement can include at least one of lithium-rich cobalt oxide Li6CoO4, lithium-rich nickel oxide Li2NiO2, lithium-rich ferrite Li5FeO4, lithium oxide Li2O, lithium peroxide Li2O2, lithium sulfide Li2S, lithium nitride Li3N, lithium carbonate Li2CO3, and lithium oxalate Li2C2O4. The lithium supplement can be evenly coated on the surface of titanium dioxide through a three-dimensional network structure formed by the combination of titanium dioxide and the lithium supplement in the composite lithium supplement, thereby avoiding the occurrence of a local lithium source negative electrode. At the same time, the lithium ions provided by the lithium supplement can make up for the loss of lithium ions caused by irreversible cycles, thereby improving the capacity retention rate of the battery.

[0053] In one embodiment of the present application, the lithium supplement may be lithium-rich lithium ferrite. Lithium-rich lithium ferrite generally offers advantages such as high efficiency, high cost-effectiveness, high safety, and high compatibility, making it easily adaptable to current battery manufacturing processes. Furthermore, lithium-rich lithium ferrite also features a simple synthesis process, low economic cost, and high electrochemical safety, making it suitable for use as a lithium supplement in batteries.

[0054] In one embodiment of the present application, the covering layer may further include a binder.

[0055] Specifically, the coating layer may further include a binder, which can be used to provide good bonding properties so that the lithium supplement adheres neatly to the surface of titanium dioxide, achieving uniform physical arrangement and consistency in thickness.

[0056] Generally speaking, lithium supplements easily react with water in the air, resulting in the consumption of the lithium supplements, making it impossible for the lithium supplements to effectively improve the capacity retention rate of the battery. In addition, the reaction of lithium supplements with moisture in the air may also cause safety risks to the battery.

[0057] By adding a binder to the coating layer in the embodiment of the present application, the interface stability of the composite lithium supplement can also be enhanced by the binder, so that the composite lithium supplement is not easily reacted with moisture in the air, has good moisture resistance, is not easily consumed, can still maintain a good capacity retention rate in a high humidity environment, and can have good safety.

[0058] In one embodiment of the present application, the adhesive may include a first adhesive and / or a second adhesive;

[0059] The first binder may include at least one of polyacrylic acid (PAA), polyvinyl pyrrolidone (PVP), epoxy resin, polyurethane (PU), polyvinylidene fluoride (PVDF), and polyvinyl alcohol (PVA);

[0060] The second binder may include at least one of carboxymethyl cellulose lithium (CMC-Li), polyacrylate lithium (PAA-Li), and polystyrene sulfonate lithium (PSS-Li).

[0061] Specifically, the first binder generally has good bonding properties, which can enable the lithium supplement agent to be closely attached to the surface of titanium dioxide.

[0062] Specifically, the second binder can not only neatly adhere the lithium supplement to its surface, but also provide more active lithium for the battery, further improving battery performance. It can provide additional lithium ions to the lithium battery, increasing the overall number of lithium ions. This can not only increase the number of lithium ions inserted and extracted between the positive and negative electrodes, improving the battery's specific capacity, but also enhance the battery's cycle efficiency, shorten the path of lithium ion movement between the positive and negative electrodes, and reduce interfacial impedance.

[0063] In a specific implementation, when the first binder is polyvinyl pyrrolidone, polyvinyl pyrrolidone can provide a strong polar lactam hydrophilic group, which combines with the three-dimensional network structure of titanium dioxide to further enhance the interface stability of the composite lithium supplement.

[0064] In one embodiment of the present application, the mass ratio of titanium dioxide to the lithium supplement is (5-20): (1-2). Among them, the mass ratio can be specifically 5:2, 4:1, 5:1, 10:1, 15:1, 17:1, 20:1, etc., and this application does not limit this. At this mass ratio, titanium dioxide can more fully provide a three-dimensional network structure for the lithium supplement, supporting the lithium supplement to be evenly and smoothly dispersed on the surface of titanium dioxide, thereby improving the overall safety of the composite lithium supplement.

[0065] In one embodiment of the present application, the mass ratio of the lithium supplement agent to the binder is (1-2): (3-4). Among them, the mass ratio can be 1:4, 3:8, 1:2, 4:7, 2:3, etc., and the present application does not limit this. Under this mass ratio, the composite lithium supplement agent can contain more lithium supplement agent as a whole, which can provide sufficient active lithium ions. At the same time, the binder can fully wrap the lithium supplement agent and tightly adhere the lithium supplement agent to the surface of titanium dioxide, so that the lithium supplement agent can be evenly dispersed on the surface of titanium dioxide, thereby improving the overall safety of the composite lithium supplement agent.

[0066] In one embodiment of the present application, when the binder includes a first binder and a second binder, the mass ratio of the first binder to the second binder is (1-5):(1-5). The mass ratio can be 1:5, 2:5, 3:5, 4:5, 5:5, 5:4, 5:3, 5:2, 5:1, etc., and the present application does not impose any restrictions on this. At this mass ratio, the binder can contain an appropriate amount of the second binder, which can better increase the content of active lithium ions in the lithium-ion battery.

[0067] The present embodiment also provides a method for preparing the composite lithium supplement as described in the embodiment of the present application, the method comprising:

[0068] Step 101, mixing a lithium supplement agent and titanium dioxide having a three-dimensional network structure to obtain a mixture;

[0069] In the embodiment of the present application, the lithium supplement agent and titanium dioxide having a three-dimensional network structure may be mixed first to obtain a mixture.

[0070] Specifically, the lithium supplement agent can be first dispersed in a solvent to obtain a dispersion. The solvent can be diethyl carbonate (DME), ethanol, water, or any other solvent capable of dispersing the lithium supplement agent, and this application is not limited thereto. Subsequently, titanium dioxide having a three-dimensional network structure is added to the dispersion, allowing the lithium supplement agent and the titanium dioxide having a three-dimensional network structure to mix to obtain a mixture.

[0071] In a specific implementation, during the process of adding the titanium dioxide having a three-dimensional network structure into the dispersion, the dispersion may be subjected to ultrasonic treatment so that the mixture can be fully and uniformly dispersed in the solvent.

[0072] In one embodiment of the present application, the step of mixing the lithium supplement agent and the titanium dioxide having a three-dimensional network structure to obtain a mixture includes: mixing the lithium supplement agent, the titanium dioxide having a three-dimensional network structure and a binder to obtain a mixture.

[0073] A mixture is obtained by mixing a lithium supplement agent, titanium dioxide with a three-dimensional network structure and a binder. The binder enables the lithium supplement agent to be better attached to the surface of the titanium dioxide with a three-dimensional network structure.

[0074] In one embodiment of the present application, the mass ratio of titanium dioxide with a three-dimensional network structure, a lithium supplement agent, and a binder is (5-20): (1-2): (3-4). Among them, the mass ratio can be 5:1:4, 20:1:3, 5:2:3, 10:1:3.5, 15:1.5:4, etc. At this mass ratio, the lithium supplement agent forms a three-dimensional network structure as a whole, which can relieve the volume stress during the charge and discharge process and improve electronic conduction. At the same time, the design of large surface area and rich pore structure can also improve the transmission efficiency of ions, thereby improving the specific capacity and cycle efficiency of the battery.

[0075] Step 102, aging the mixture to obtain an aged product in which the lithium supplementing agent is coated on at least a portion of the surface of the titanium dioxide;

[0076] The mixture can be aged. By placing the mixture for a long time, the lithium supplement agent can be coated on at least a portion of the surface of the titanium dioxide having a three-dimensional network structure to obtain an aged product.

[0077] During the aging process, the aging temperature can be controlled at room temperature for 0.1 to 8 hours. The aging time can specifically be 0.1 hour, 0.5 hour, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, etc.

[0078] In one embodiment of the present application, before the step of aging the mixture to obtain an aged product in which the lithium supplement agent is coated on at least a portion of the surface of the titanium dioxide, the process further includes:

[0079] A basic solvent is added to the mixture. The basic solvent includes anhydrous ethanol and aqueous ammonia.

[0080] Specifically, in the process of mixing the lithium supplement agent and titanium dioxide having a three-dimensional network structure to obtain a mixture, an alkaline solvent can be further added to form an alkaline environment by adjusting the pH, so that the lithium supplement agent tends to adhere to the surface of the titanium dioxide having a three-dimensional network structure.

[0081] In a specific implementation, during the process of adding the alkaline solvent, the mixture can be stirred so that the alkaline solvent can be dispersed more evenly in the mixture.

[0082] In one embodiment of the present application, the volume ratio of anhydrous ethanol to aqueous ammonia is (5-15):1. The specific volume ratio can be 5:1, 7:1, 10:1, 13:1, 15:1, etc., and the present application does not impose any limitation thereto. Within this ratio range, anhydrous ethanol can effectively assist in evenly dispersing aqueous ammonia in the mixture.

[0083] After aging is completed, the aged solution can be centrifuged, and the solid can be washed 2 to 6 times with distilled water and anhydrous ethanol respectively to obtain an aged product. The washed aged product can be dried at 20 to 90° C. for 2 to 8 hours to fully evaporate the solvent.

[0084] Step 103: calcining the aged product to obtain the composite lithium supplement.

[0085] The aged product can be further calcined so that the lithium supplement agent can be better attached to the titanium dioxide having a three-dimensional network structure to obtain a composite lithium supplement agent.

[0086] In one embodiment of the present application, the calcination temperature may be 200° C. to 800° C., and the calcination time may be 2 h to 8 h.

[0087] The calcination conditions may include calcination at 200-800°C at a heating rate of 0-6°C / min for 2-8 hours. The heating rate may be 0.1°C / min, 0.5°C / min, 1°C / min, 2°C / min, 3°C / min, 4°C / min, 5°C / min, 6°C / min, etc. The calcination temperature may be 200°C, 300°C, 400°C, 500°C, 600°C, 700°C, 800°C, etc. The calcination time may be 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, etc.

[0088] As a specific example of the present application, the preparation method of the composite lithium supplement may include the following steps:

[0089] S11, dissolving lithium-rich ferrite (Li5FeO4), polyvinyl pyrrolidone (PVP), and carboxymethyl cellulose lithium (CMC-Li) in a solvent under magnetic stirring to obtain a first dispersion;

[0090] S12, adding titanium dioxide to the first dispersion to form a uniform dispersion, and performing ultrasonic treatment for 0 to 1 hour.

[0091] S13, under magnetic stirring, dropwise adding an anhydrous ethanol solution containing aqueous ammonia, and aging at room temperature for 0 to 8 hours to obtain a solid;

[0092] S14. Centrifuge the aged solution and wash the solid matter with distilled water and anhydrous ethanol 2 to 6 times respectively.

[0093] S15, drying the washed composite lithium supplement agent at 20-90° C. for 2-8 hours to obtain a dry solid;

[0094] S16, calcining the solid at 200-800° C. at a heating rate of 0-6° C. / min for 2-8 hours to obtain a composite lithium supplement.

[0095] In a specific implementation, the titanium dioxide with a three-dimensional network structure in the embodiment of the present application can be prepared by a hydrothermal method, for example, a neat and uniform layer of titanium dioxide is grown on the surface of a pure titanium sheet by a hydrothermal method, or a three-dimensional network structure is prepared based on titanium oxysulfate, urea, and hydrofluoric acid by a hydrothermal method, etc. This application does not impose any restrictions on this.

[0096] In one embodiment of the present application, a method for preparing titanium dioxide having a three-dimensional network structure may include:

[0097] Step 201, mixing a titanium source, a pH adjuster, and a solvent to obtain a first mixture;

[0098] Step 202, mixing the first mixture and an acid to obtain a second mixture;

[0099] Step 203 , subjecting the second mixture to heat preservation treatment and then solid-liquid separation to obtain titanium dioxide having a three-dimensional network structure.

[0100] Specifically, a titanium source, a pH adjuster, and a solvent may be mixed to obtain a first mixture. The titanium source may be used to provide titanium ions, and the pH adjuster may be used to assist in adjusting the morphology of the generated titanium dioxide during the reaction.

[0101] The titanium source may generally include at least one of titanium tetrachloride, titanium sulfate, titanyl sulfate, sodium hydrogen titanate, tetrabutyl titanate, isopropyl titanate, and ethyl titanate.

[0102] The pH regulator can generally be an alkaline regulator such as ammonia, urea, sodium hydroxide, potassium hydroxide, etc., which can promote the preparation of titanium dioxide with a three-dimensional network structure.

[0103] The solvent can generally be water or other solvents that do not affect the reaction and can effectively disperse the titanium source.

[0104] After obtaining a first mixture of a titanium source, a pH adjuster, and a solvent, an acid may be mixed to obtain a second mixture.

[0105] Specifically, the acid can be used to adjust the morphology of the generated titanium dioxide, allowing it to form different crystal structures. By adjusting the ratio between the acid and the titanium source, titanium dioxide with a three-dimensional network structure can be prepared.

[0106] In one embodiment of the present application, the method satisfies at least one of the following conditions:

[0107] The titanium source may include at least one of titanium tetrachloride (TiCl4), titanium sulfate (Ti(SO4)2), titanyl sulfate (TiOSO4), sodium hydrogen titanate (NaHTiO3), tetrabutyl titanate (Ti(OC4H9)4), isopropyl titanate (Ti(OCH(CH3)2)4), and ethyl titanate (Ti(OC2H5)4);

[0108] The pH adjuster may include at least one of aqueous ammonia (NH3·H2O), urea (CO(NH2)2), sodium hydroxide (NaOH), potassium hydroxide (KOH), sodium carbonate (Na2CO3) and potassium carbonate (K2CO3);

[0109] The solvent may include deionized water;

[0110] The acid may include at least one of hydrofluoric acid (HF), hydrochloric acid (HCl), sulfuric acid (H2SO4), nitric acid (HNO3), oxalic acid (H2C2O4), tartaric acid (C4H6O6), and citric acid (C6H8O7).

[0111] In one embodiment of the present application, the weight ratio of the titanium source to the pH adjuster can be (1-100):(1-60), for example, 1:60, 2:5, 2:4, 1:1, 4:3, 5:2, 5:3, 6:1, 4:1, 35:1, 80:1, 90:1, 100:1, etc.

[0112] In a specific implementation, the acid can be used to adjust the morphology of the generated titanium dioxide, allowing it to form various morphologies such as particles, elongated strips, and three-dimensional network structures. When the weight ratio of the titanium source to the pH adjuster is (1-100):(1-60), the titanium dioxide formed is more likely to form a three-dimensional network structure.

[0113] In one embodiment of the present application, the molar ratio nTi / nH between the titanium element in the titanium source and the hydrogen element in the acid is 0.35 to 0.5, for example, 0.35, 0.4, 0.45, 0.5, etc. At this molar ratio, the acid can control the formed titanium dioxide to have a three-dimensional network structure.

[0114] After obtaining the second mixture, the second mixture can be subjected to a heat preservation treatment to allow the titanium source to hydrolyze and crystallize at high temperature, forming titanium dioxide having a three-dimensional network structure. The second mixture after the high temperature treatment can then be subjected to a solid-liquid separation treatment to remove the solution and retain the titanium dioxide.

[0115] In one embodiment of the present application, the heat preservation treatment satisfies at least one of the following conditions:

[0116] The temperature of the heat preservation treatment is 20℃~200℃;

[0117] The insulation treatment time is 4h to 20h.

[0118] In one embodiment of the present application, the heating rate of the heat preservation treatment may be 0° C. / min to 10° C. / min.

[0119] In a specific implementation, the morphology of the titanium dioxide prepared can be controlled by controlling at least one of the heating rate, temperature, and holding time of the holding treatment.

[0120] Among them, the heating rate of the insulation treatment can be 0℃ / min~10℃ / min, for example, 0.1℃ / min, 0.5℃ / min, 1℃ / min, 2℃ / min, 3℃ / min, 5℃ / min, 7℃ / min, 9℃ / min, 10℃ / min, etc.

[0121] The temperature of the heat preservation treatment is 20°C to 200°C, for example, 20°C, 50°C, 80°C, 100°C, 120°C, 150°C, 180°C, 200°C, etc.

[0122] The insulation time of the insulation treatment can be 4 hours to 20 hours, for example, 4 hours, 6 hours, 8 hours, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, etc.

[0123] As a specific example of the present application, a method for preparing titanium dioxide having a three-dimensional network structure may include:

[0124] S21, dissolving 0.05-2.0 g of titanyl sulfate and 0.02-3.0 g of urea in 20.0-60.0 mL of deionized water and stirring evenly for 10-60 min;

[0125] S22. Different amounts of hydrofluoric acid (1.10 mL, 1.20 mL, 1.35 mL, and 1.55 mL, corresponding to nTi / nH ratios of 0.50, 0.45, 0.40, and 0.35, respectively) were slowly added dropwise to the above solution, and the mixture was stirred for about 10-60 min until the solution became clear.

[0126] S23, transfer the above solution to a 100 mL tetrafluoroethylene-lined reactor, set the temperature to 20°C to 200°C at a rate of 0°C / min to 10°C / min, and keep the temperature for 4 to 20 hours.

[0127] S24, after cooling, filtering the obtained product, washing it with ethanol for 2 to 5 times, and then washing it with deionized water for 1 to 5 times, placing the product in a vacuum drying oven, and drying it at 20 to 80° C. for 12 to 48 hours to obtain titanium dioxide with a three-dimensional network structure.

[0128] The embodiments of the present application further provide a battery, comprising a positive electrode sheet, wherein the positive electrode sheet comprises the composite lithium supplement described in the embodiments of the present application, or the composite lithium supplement prepared by the preparation method described in the embodiments of the present application.

[0129] Specifically, a lithium-ion battery may include a positive electrode sheet, a negative electrode sheet, a separator arranged between the positive electrode sheet and the negative electrode sheet, and an electrolyte dispersed in the lithium-ion battery; the positive electrode sheet includes a current collector and a positive electrode active material layer arranged on at least one side of the current collector, and the positive electrode active material layer includes the composite lithium supplement described in the embodiment of the present application, or the composite lithium supplement prepared by the preparation method described in the embodiment of the present application.

[0130] An embodiment of the present application further provides a battery pack, which includes the battery described in the embodiment of the present application.

[0131] An embodiment of the present application further provides an electrical device, which includes the battery described in the embodiment of the present application or the battery pack described in the embodiment of the present application.

[0132] The electrical equipment in the embodiments of the present invention can be conventional electrical equipment in the field, such as power equipment (such as electric vehicles, electric cars), electronic equipment (such as mobile phones, tablets, laptops, digital cameras, etc.), wearable devices (such as watches, bracelets, VR glasses, etc.), energy storage power stations, etc., without special restrictions.

[0133] The composite lithium supplement agent of the embodiment of the present application includes titanium dioxide with a three-dimensional network structure, and a coating layer coated on at least a portion of the surface of the titanium dioxide, wherein the coating layer includes a lithium supplement agent. The composite lithium supplement agent forms a three-dimensional network structure through the titanium dioxide with a three-dimensional network structure and the coating layer as a whole, which can relieve the volume stress during the charge and discharge process and improve electronic conduction. At the same time, the composite lithium supplement agent that forms a three-dimensional network structure as a whole has a large surface area and a rich pore structure. The design of a large surface area and a rich pore structure can also improve the transmission efficiency of ions, and the three-dimensional network structure can better disperse the active lithium in the lithium supplement agent evenly, reduce the occurrence of local lithium source enrichment, thereby improving the capacity retention rate of the battery and reducing the internal resistance. At the same time, the composite lithium supplement agent obtained can have good moisture resistance, is not easy to react with water in the air, and can still have a good capacity retention rate in a high humidity environment.

[0134] In order to enable those skilled in the art to better understand the present application, the preparation method of the lithium-ion battery containing the composite lithium supplement agent of the present application is described below through multiple specific examples.

[0135] Example 1

[0136] 1) Under magnetic stirring, 4 parts by weight of lithium-rich ferrite (Li5FeO4), 3 parts by weight of polyvinyl pyrrolidone (PVP), and 3 parts by weight of carboxymethyl cellulose lithium (CMC-Li) are dissolved in deionized water as a solvent to obtain a first dispersion;

[0137] 2) adding titanium dioxide to the first dispersion to form a uniform dispersion, and ultrasonically treating the dispersion for 1 hour, wherein the mass ratio of titanium dioxide to lithium supplement is 10:1.

[0138] The preparation steps of titanium dioxide are as follows:

[0139] First, dissolve 1.5 g of titanyl sulfate and 2.5 g of urea in 60 mL of deionized water and stir evenly for 30 min.

[0140] Second, slowly add 1.35 mL of hydrofluoric acid (corresponding to a nTi / nH ratio of 0.40) to the above solution and stir for about 30 minutes until the solution becomes clear.

[0141] Third, the above solution was transferred to a 100 mL tetrafluoroethylene-lined reactor, and the temperature was programmed to 180°C at 8°C / min and kept at this temperature for 8 h.

[0142] Fourth, after cooling, the obtained product was filtered, washed with ethanol 4 times, and then washed with deionized water 4 times, and the sample was placed in a vacuum drying oven and dried at 60° C. for 24 h.

[0143] 3) Under magnetic stirring, 5 ml of anhydrous ethanol solution containing 10% ammonia was added dropwise, and the mixture was aged at room temperature for 6 hours to obtain a solid;

[0144] 4) The aged solution was centrifuged and the solids were washed four times with distilled water and anhydrous ethanol respectively.

[0145] 5) drying the washed composite lithium supplement at 60° C. for 6 h to obtain a dry solid;

[0146] 6) calcining the solid at 500° C. at a heating rate of 6° C. / min for 4 h to obtain a composite lithium supplement.

[0147] 7) Using lithium iron phosphate as the active material, it is uniformly mixed with a conductive agent, activated carbon (Swiss SuperP), a binder, polyvinylidene fluoride (PVDF), and a composite lithium supplement in a nitrogen methyl pyrrolidone (NMP) solution. The mass ratio of the active material, activated carbon (SuperP), binder, and composite lithium supplement is 80:10:10:5, respectively. The mixture is then coated and pressed onto aluminum foil to produce a positive electrode sheet.

[0148] 8) Mixing the negative electrode active material, carbon black, CMC, and SBR in a mass ratio of 96.5:0.5:1.2:1.8, coating the mixture on a copper foil, and then drying the mixture at 90° C. to obtain a negative electrode sheet;

[0149] 9) The positive electrode sheet, negative electrode sheet, and ceramic separator were assembled into a laminated soft pack battery with a capacity of 1.1 Ah, and an electrolyte was injected into the battery to obtain a lithium-ion battery S1. The electrolyte comprised, by weight, 12.5% ​​lithium hexafluorophosphate + 2% vinylene carbonate (VC) + 85.5% solvent, where the solvent was ethylene carbonate (EC) and dimethyl carbonate (DMC) in a volume ratio of 1:1.

[0150] Example 2

[0151] Example 2 is basically the same as Example 1, and a lithium ion battery S2 is obtained.

[0152] The difference is that the mass ratio between titanium dioxide and lithium supplement is 5:1.

[0153] Example 3

[0154] Example 3 is basically the same as Example 1, and a lithium ion battery S3 is obtained.

[0155] The difference is that the first dispersion contains 4 parts by weight of lithium-rich lithium ferrite, 5 parts by weight of polyvinyl pyrrolidone (PVP), and 1 part by weight of carboxymethyl cellulose lithium (CMC-Li); and the mass ratio between titanium dioxide and the lithium supplement is 10:1.

[0156] Example 4

[0157] Example 4 is basically the same as Example 1, and a lithium ion battery S4 is obtained.

[0158] The difference is that the first dispersion contains 4 parts by weight of lithium-rich lithium ferrite, 5 parts by weight of polyvinyl pyrrolidone (PVP), and 1 part by weight of carboxymethyl cellulose lithium (CMC-Li); and the mass ratio between titanium dioxide and the lithium supplement is 5:1.

[0159] Example 5

[0160] Example 5 is basically the same as Example 1, and a lithium-ion battery S5 is obtained.

[0161] The difference is that the first dispersion contains 4 parts by weight of lithium-rich lithium ferrite, 5 parts by weight of polyvinyl pyrrolidone (PVP), and 1 part by weight of carboxymethyl cellulose lithium (CMC-Li); and the mass ratio between titanium dioxide and the lithium supplement is 10:1.

[0162] Example 6

[0163] Example 6 is basically the same as Example 1, and a lithium-ion battery S6 is obtained.

[0164] The difference is that the first dispersion contains 4 parts of lithium-rich lithium ferrite, 1 part of polyvinyl pyrrolidone (PVP), and 5 parts of carboxymethyl cellulose lithium (CMC-Li); the mass ratio between titanium dioxide and lithium supplement is 5:1.

[0165] Example 7

[0166] Example 7 is basically the same as Example 1, and a lithium ion battery S7 is obtained.

[0167] The difference is that the first dispersion contains 2 parts of lithium-rich lithium ferrite, 6 parts of polyvinyl pyrrolidone (PVP), and 2 parts of carboxymethyl cellulose lithium (CMC-Li); the mass ratio between titanium dioxide and lithium supplement is 20:1.

[0168] Example 8

[0169] Example 8 is basically the same as Example 1, and a lithium-ion battery S8 is obtained.

[0170] The difference is that the first dispersion contains 2 parts of lithium-rich lithium ferrite, 6 parts of polyvinyl pyrrolidone (PVP), and 2 parts of carboxymethyl cellulose lithium (CMC-Li); the mass ratio between titanium dioxide and lithium supplement is 10:1.

[0171] Example 9

[0172] Example 9 is basically the same as Example 1, and a lithium-ion battery S9 is obtained.

[0173] The difference is that the first dispersion includes 4 parts of lithium-rich lithium ferrite and does not contain a binder; the mass ratio of titanium dioxide to lithium-rich lithium ferrite is 10:1.

[0174] Comparative Example 1

[0175] 1) Lithium iron phosphate material is used as the active material, and is uniformly mixed with a conductive agent activated carbon (Swiss SuperP), and a binder polyvinylidene fluoride (PVDF) in a nitrogen methyl pyrrolidone (NMP) solution. The mass ratio of the active material, activated carbon (SuperP), and binder is 80:10:10, respectively. The mixture is then coated and pressed onto aluminum foil to produce a positive electrode sheet.

[0176] 2) mixing the negative electrode active material, carbon black, CMC, and SBR in a mass ratio of 96.5:0.5:1.2:1.8, coating the mixture on a copper foil, and then drying the mixture at 90° C. to obtain a negative electrode sheet;

[0177] 3) The positive electrode sheet, negative electrode sheet, and ceramic separator were assembled into a 1.1Ah soft pack battery in the form of a stack, and an electrolyte was injected to obtain a lithium-ion battery RS1. The electrolyte comprises, by weight, 12.5% ​​lithium hexafluorophosphate + 2% vinylene carbonate (VC) + 85.5% solvent, where the solvent is ethylene carbonate (EC) and dimethyl carbonate (DMC) in a 1:1 volume ratio.

[0178] Comparative Example 2

[0179] 1) 4 parts of lithium-rich lithium ferrite (Li5FeO4), 3 parts of polyvinyl pyrrolidone (PVP), and 3 parts of carboxymethyl cellulose lithium (CMC-Li) are mixed to obtain a lithium supplement.

[0180] 2) Using lithium iron phosphate as the active material, it is uniformly mixed with a conductive agent, activated carbon (Swiss SuperP), a binder, and a lithium supplement agent in a nitrogen methyl pyrrolidone (NMP) solution. The mass ratio of the active material, activated carbon (SuperP), binder, and lithium supplement agent is 80:10:10:5, respectively. The mixture is then coated and pressed onto aluminum foil to produce a positive electrode sheet.

[0181] 2) mixing the negative electrode active material, carbon black, CMC, and SBR in a mass ratio of 96.5:0.5:1.2:1.8, coating the mixture on a copper foil, and then drying the mixture at 90° C. to obtain a negative electrode sheet;

[0182] 3) The positive electrode sheet, the negative electrode sheet, and the ceramic separator are assembled into a soft-pack battery with a capacity of 1.1 Ah in the form of a stack, and an electrolyte is injected to obtain a lithium-ion battery RS2.

[0183] Comparative Example 3

[0184] Comparative Example 3 is basically the same as Comparative Example 2, and a lithium ion battery RS3 is obtained.

[0185] The difference is that the lithium supplement contains 4 parts of lithium-rich lithium ferrite, 5 parts of polyvinyl pyrrolidone (PVP), and 1 part of carboxymethyl cellulose lithium (CMC-Li).

[0186] Comparative Example 4

[0187] Comparative Example 4 is basically the same as Comparative Example 2, and a lithium-ion battery RS4 is obtained.

[0188] The difference is that the lithium supplement contains 4 parts of lithium-rich lithium ferrite, 1 part of polyvinyl pyrrolidone (PVP), and 5 parts of carboxymethyl cellulose lithium (CMC-Li).

[0189] Comparative Example 5

[0190] Comparative Example 5 is substantially the same as Comparative Example 2, and a lithium-ion battery RS5 is obtained.

[0191] The difference is that the lithium supplement contains 2 parts of lithium-rich lithium ferrite, 6 parts of polyvinyl pyrrolidone (PVP), and 2 parts of carboxymethyl cellulose lithium (CMC-Li).

[0192] Comparative Example 6

[0193] Comparative Example 6 is basically the same as Comparative Example 1, and a lithium-ion battery RS6 is obtained.

[0194] The difference is that titanium dioxide with a non-three-dimensional network structure (purchased from Shanghai Huijingya Nano New Materials Co., Ltd.) is used, and the mass ratio of titanium dioxide to lithium-rich lithium ferrite is 10:1.

[0195] The lithium ion batteries prepared in Examples 1 to 9 and Comparative Examples 1 to 6 were subjected to electrochemical performance tests, including:

[0196] Cycle test:

[0197] 1) Pre-cycle: Perform constant current and constant voltage charging at 25°C, charge to 3.5V at a constant current of 0.03C, and then charge to 3.8V at a constant current of 0.5C.

[0198] 2) After the pre-cycling, the airbag was removed in an inert gas glove box and the battery was finally sealed. After final sealing, the battery was subjected to a charge-discharge cycle test in a 25°C constant-temperature chamber. Specifically, within the 2.0-3.8V range, the battery was first charged at 0.1C to 3.8V. After a 1-minute rest, it was discharged at a constant current of 0.1C to a cutoff voltage of 2.0V. This constituted one cycle, and other conditions remained unchanged for 300 cycles. The results are shown in Table 2.

[0199] Internal resistance test:

[0200] A lithium-ion battery was subjected to one charge-discharge cycle at room temperature at a charge-discharge rate of 3C / 10s. The battery's internal resistance, T, was recorded. The internal resistance was measured using a ZRX-14393 battery internal resistance tester. The results are shown in Table 1.

[0201] Table 1 Test results of capacity retention and resistance of lithium-ion batteries

[0202]

[0203]

[0204] It can be seen that the capacity retention rate of the lithium-ion battery RS1 without a lithium supplement agent is low and the internal resistance is relatively large. The capacity retention rate and internal resistance of the lithium-ion batteries RS2 to RS5 containing a lithium supplement agent but without titanium dioxide having a three-dimensional structure are improved to a certain extent. The capacity retention rate and internal resistance of the lithium-ion batteries S1 to S9 containing a composite lithium supplement agent and the composite lithium supplement agent containing titanium dioxide having a three-dimensional structure are significantly better than those of the lithium-ion batteries prepared in the comparative examples.

[0205] Moisture resistance test:

[0206] The composite lithium supplement was stored in a constant temperature and humidity chamber and then tested for lithium recharge capacity. The moisture resistance of the composite lithium supplement was evaluated by comparing the lithium recharge capacity retention before and after storage. The storage temperature was 25°C, the humidity was 75%, and the storage time was 3 days and 7 days, respectively. The lithium recharge capacity retention ratio = (initial discharge capacity in grams after storage) / (initial discharge capacity in grams before storage) * 100%. The results are shown in Table 2.

[0207] Table 2 Test results of moisture resistance test

[0208]

[0209]

[0210] It can be seen that the overall moisture resistance of the composite lithium supplement agent of the present application example is superior to that of the comparative example. Furthermore, a comparison of S1-S8 with S9 shows that the present application example enhances the interface stability of the composite lithium supplement agent by combining the binder with the three-dimensional titanium dioxide structure, thereby improving the moisture resistance of the lithium supplement agent.

[0211] Component analysis test

[0212] The lithium-ion batteries obtained in the examples and comparative examples were disassembled in an inert gas glove box to remove the residual electrolyte from the batteries. The samples were diluted with ethyl acetate to an appropriate multiple, and 1 μL was aspirated with a microsyringe for analysis. The results are recorded in Table 3.

[0213] Table 3 Test results of lithium supplement composition and content

[0214] Battery number PVP CMC-Li <![CDATA[Li5FeO4]]> S1 1.21％ 1.31％ 2.51％ S2 2.32％ 2.63％ 4.65％ S3 2.23％ 0.38％ 1.91％ S4 4.51％ 0.96％ 2.83％ S5 0.23％ 2.37％ 1.67％ S6 0.92％ 4.25％ 2.34％ S7 3.67％ 0.19％ 0.32％ S8 5.17％ 0.41％ 0.73％ RS1 0％ 0％ 0％ RS2 2.09％ 2.43％ 3.01％ RS3 3.23％ 1.42％ 2.15％ RS4 1.32％ 2.96％ 2.45％ RS5 4.85％ 0.99％ 0.92％

[0215] It can be seen that the composite lithium supplement agent of the present application can be more fully utilized in the battery compared with the comparative example, thereby improving the lithium supplement effect of the composite lithium supplement agent.

[0216] The above describes in detail a composite lithium supplement agent and a preparation method thereof, and a lithium-ion battery provided by the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only intended to help understand the method and core ideas of the present application. At the same time, for those skilled in the art, according to the ideas of the present application, there may be changes in the specific implementation methods and application scopes. In summary, the contents of this specification should not be understood as limiting the present application.

Claims

1. A composite lithium supplement, characterized in that: The composite lithium supplement agent includes titanium dioxide having a three-dimensional network structure and a coating layer coated on at least a portion of the surface of the titanium dioxide, wherein the coating layer includes the lithium supplement agent.

2. The composite lithium supplement according to claim 1, characterized in that The titanium dioxide is in a nanobelt structure.

3. The composite lithium supplement according to claim 1, characterized in that The lithium supplement comprises at least one of lithium-rich lithium cobaltate, lithium-rich lithium nickelate, lithium-rich lithium ferrite, lithium oxide, lithium peroxide, lithium sulfide, lithium nitride, lithium carbonate, and lithium oxalate.

4. The composite lithium supplement according to claim 3, characterized in that The lithium supplement is lithium-rich lithium ferrite.

5. The composite lithium supplement according to claim 1, characterized in that The coating layer also includes a binder.

6. The composite lithium supplement according to claim 5, characterized in that The binder includes a first binder and / or a second binder; The first binder includes at least one of polyacrylic acid, polyvinyl pyrrolidone, epoxy resin, polyurethane, polyvinylidene fluoride and polyvinyl alcohol; the second binder includes at least one of lithium carboxymethyl cellulose, lithium polyacrylate and lithium polystyrene sulfonate.

7. The composite lithium supplement according to claim 1, characterized in that The mass ratio of the titanium dioxide to the lithium supplement agent is (5-20):(1-2).

8. The composite lithium supplement according to claim 5, characterized in that The mass ratio of the lithium supplement agent to the binder is (1-2):(3-4).

9. The composite lithium supplement according to claim 6, characterized in that The binder includes a first binder and a second binder, and the mass ratio of the first binder to the second binder is (1-5):(1-5).

10. A method for preparing the composite lithium supplement according to any one of claims 1 to 9, characterized in that: The method comprises: mixing the lithium supplement agent and the titanium dioxide having a three-dimensional network structure to obtain a mixture; performing an aging treatment on the mixture to obtain an aging product in which the lithium supplementing agent is coated on at least a portion of the surface of the titanium dioxide; The aged product is calcined to obtain the composite lithium supplement agent.

11. The method for preparing the composite lithium supplement according to claim 10, wherein: The step of mixing the lithium supplement agent and the titanium dioxide having a three-dimensional network structure to obtain a mixture comprises: The lithium supplement agent, the titanium dioxide having a three-dimensional network structure and a binder are mixed to obtain a mixture.

12. The method for preparing the composite lithium supplement according to claim 11, characterized in that: The mass ratio of the titanium dioxide with a three-dimensional network structure, the lithium supplement agent and the binder is (5-20):(1-2):(3-4).

13. The method for preparing the composite lithium supplement according to claim 10, characterized in that: Before the step of aging the mixture to obtain an aged product in which the lithium supplement agent is coated on at least a portion of the surface of the titanium dioxide, the process further comprises: A basic solvent is added to the mixture, wherein the basic solvent comprises anhydrous ethanol and aqueous ammonia.

14. The method for preparing the composite lithium supplement according to claim 13, wherein: The volume ratio between the anhydrous ethanol and the ammonia water is (5-15):

1.

15. The method for preparing the composite lithium supplement according to claim 10, characterized in that: The calcination temperature is 200° C. to 800° C., and the calcination time is 2 hours to 8 hours.

16. The method for preparing a composite lithium supplement according to any one of claims 10 to 15, characterized in that: The preparation method of titanium dioxide having a three-dimensional network structure comprises: mixing a titanium source, a pH adjuster, and a solvent to obtain a first mixture; mixing the first mixture and an acid to obtain a second mixture; The second mixture is subjected to heat preservation treatment and then solid-liquid separation to obtain the titanium dioxide having a three-dimensional network structure.

17. The method for preparing the composite lithium supplement according to claim 16, characterized in that: At least one of the following conditions is met: The titanium source includes at least one of titanium tetrachloride, titanium sulfate, titanyl sulfate, sodium hydrogen titanate, tetrabutyl titanate, isopropyl titanate, and ethyl titanate; The pH regulator includes at least one of ammonia water, urea, sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate; The solvent includes deionized water; The acid includes at least one of hydrofluoric acid, hydrochloric acid, sulfuric acid, nitric acid, oxalic acid, tartaric acid and citric acid.

18. The method for preparing the composite lithium supplement according to claim 16 or 17, characterized in that: The weight ratio of the titanium source to the pH adjuster is (1-100):(1-60); and / or, The molar ratio between the titanium element in the titanium source and the hydrogen element in the acid is 0.35 to 0.

5.

19. The method for preparing the composite lithium supplement according to claim 16 or 17, characterized in that: The heat preservation treatment satisfies at least one of the following conditions: The temperature of the heat preservation treatment is 20°C to 200°C; The heat preservation treatment time is 4h to 20h.

20. A battery, characterized in that: The battery includes a positive electrode sheet, and the positive electrode sheet includes the composite lithium supplement according to any one of claims 1 to 9, or the composite lithium supplement prepared by the preparation method according to any one of claims 10 to 19.

21. A battery pack, characterized in that: The battery pack includes the battery according to claim 20.

22. An electrical device, characterized in that: The electric device comprises the battery according to claim 20 or the battery pack according to claim 21.

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