Doped lithium supplement additive, preparation method and application thereof

Abstract

The present application discloses a doped lithium supplement additive, a preparation method thereof, and an application. The crystal phase of the doped lithium supplement additive in the present application contains a lithium supplement material matrix phase and a doped phase, and the doped phase includes metal oxides. Through the crystal phase doping of metal oxides, the doped lithium supplement additive in the present application can effectively inhibit the formation of harmful microcracks in the crystal of the doped lithium supplement additive while endowing the doped lithium supplement additive with an efficient lithium supplement function, improve the stability of the crystal structure of the doped lithium supplement additive, and thus improve the cycle stability of the doped lithium supplement additive. The preparation method of the doped lithium supplement additive can ensure the stability of the structure and electrochemical performance of the prepared doped lithium supplement additive, and has high efficiency and low production cost.

Description

Technical Field

[0001] The present application belongs to the technical field of electrode active materials, and specifically relates to a doped lithium supplement additive and a preparation method and application thereof. Background Art

[0002] The oil energy crisis in the 1960s and 1970s forced people to look for new alternative energy sources. As people's awareness of environmental protection and energy crisis increased, lithium-ion batteries are considered to be one of the most promising energy sources due to their high operating voltage and energy density, relatively small self-discharge level, no memory effect, no heavy metal pollution such as lead and cadmium, and ultra-long cycle life.

[0003] During the first charging process of lithium-ion batteries, the negative electrode surface is usually accompanied by the formation of a solid electrolyte membrane SEI film, which consumes a large amount of Li + , which means that Li released from the electrode material + Part of it is irreversibly consumed, and the reversible specific capacity of the corresponding battery cell is reduced. The negative electrode material, especially the silicon-based negative electrode material, will further consume Li + , resulting in lithium loss in the electrode material, reducing the battery's initial coulombic efficiency and battery capacity. For example, in a lithium-ion battery system using a graphite negative electrode, the first charge will consume about 10% of the lithium source. When using high-capacity negative electrode materials, such as alloys (silicon, tin, etc.), oxides (silicon oxide, tin oxide) and amorphous carbon negative electrodes, the consumption of the electrode lithium source will be further aggravated.

[0004] In order to improve the low coulombic efficiency problem caused by irreversible loss of the negative electrode, it is currently proposed to add irreversible lithium supplement additives to the electrode or negative electrode to release lithium ions as a "sacrificial agent" during the first cycle of charging to supplement the irreversible lithium ions consumed by the formation of the SEI film at the negative electrode. However, in research and application, it was found that the lithium supplement additives that have been publicly reported have unsatisfactory lithium supplement effects, and the lithium supplement additives have internal stress problems, which lead to unstable particles during the lithium supplement process, such as the easy occurrence of harmful microcracks, which leads to unstable lithium supplement effects. Summary of the invention

[0005] The purpose of the present application is to overcome the above-mentioned deficiencies of the prior art and to provide a doped lithium supplement additive and a preparation method thereof, so as to solve the technical problems of the existing lithium supplement additives such as unsatisfactory lithium supplement effect and unstable material particle structure.

[0006] Another object of the present application is to provide an electrode and a secondary battery containing the electrode to solve the technical problems of the existing secondary batteries being prone to polarization and having low capacity.

[0007] To achieve the above application objectives, in the first aspect of the present application, a doped lithium supplement additive is provided. The doped lithium supplement additive of the present application includes lithium supplement material particles, and a lithium supplement material matrix phase and a doped phase are contained in the crystal of the lithium supplement material particles, wherein the doped phase includes metal oxides.

[0008] In the second aspect of the present application, a preparation method of the doped lithium supplement additive of the present application is provided. The preparation method of the doped lithium supplement additive of the present application includes the following steps:

[0009] Provide a lithium supplement material precursor containing a doped element; wherein the doped element is at least used to form a doped phase;

[0010] Mix the lithium supplement material precursor with a lithium source to obtain a precursor mixture;

[0011] Sinter the precursor mixture in a protective atmosphere to obtain the doped lithium supplement additive.

[0012] In the third aspect of the present application, an electrode is provided. The electrode of the present application includes a current collector and an electrode active layer combined on the surface of the current collector, and the electrode active layer contains the doped lithium supplement additive of the present application or the doped lithium supplement additive prepared by the preparation method of the doped lithium supplement additive of the present application.

[0013] In the fourth aspect of the present application, a secondary battery is provided. The secondary battery of the present application includes the electrode of the present application.

[0014] Compared with the prior art, the present application has the following technical effects:

[0015] The lithium supplement material matrix phase contained in the doped lithium supplement additive of the present application is rich in lithium, which can supplement the lithium ions consumed in the formation of the SEI film during the first charge and discharge process of the battery, and improve the first charge specific capacity of the battery. The doped phase contained in the doped lithium supplement additive of the present application can not only offset the loss of active lithium caused by the formation of the SEI film, alleviate the irreversible capacity loss in the first cycle, thereby improving the total capacity and energy density of the battery; but also reduce the internal strain of the doped lithium supplement additive crystal in the form of crystal phase doping, inhibit the formation of harmful microcracks in the doped lithium supplement additive crystal, improve the stability of the doped lithium supplement additive crystal structure, and thus improve the cycle stability of the doped lithium supplement additive.

[0016] The preparation method of the doped lithium supplement additive of the present application can effectively prepare the doped lithium supplement additive with a crystal phase of a lithium supplement material matrix phase and a doped phase, endowing the prepared doped lithium supplement additive with excellent lithium supplement effect and stable crystal structure. In addition, the preparation method of the doped lithium supplement additive can ensure the stability of the structure and electrochemical performance of the prepared doped lithium supplement additive, and has high efficiency and saves production costs.

[0017] Since the electrode of the present application contains the doping lithium supplement additive of the present application, the first charge specific capacity of the electrode of the present application is high, and the cycle performance is high and the life is long.

[0018] Since the secondary battery of the present application contains the electrode of the present application, the secondary battery of the present application has high energy density, first charge specific capacity and cycle performance, and the electrochemical performance is stable. Description of the Drawings

[0019] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0020] Figure 1 Schematic flow chart of the preparation method of the doping lithium supplement additive in the embodiment of the present application;

[0021] Figure 2 SEM image of the doping lithium supplement additive provided in Example A1;

[0022] Figure 3 First charge and discharge curve of the doping lithium supplement additive provided in Example A1;

[0023] Figure 4 XRD spectrum of the doping lithium supplement additive provided in Example A5. Detailed Description of the Embodiments

[0024] In order to make the technical problems to be solved, technical solutions and beneficial effects of the present application clearer, the following further details the present application in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0025] In the present application, the term "and / or" describes the association relationship of the associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Wherein A and B can be singular or plural. The character " / " generally represents an "or" relationship between the front and rear associated objects.

[0026] In this application, "at least one" means one or more, and "a plurality" means two or more. "At least one of the following" or a similar expression means any combination of these items, including any combination of single item(s) or plural item(s). For example, "at least one of a, b, or c", or "at least one of a, b, and c" can both represent: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively.

[0027] It should be understood that in various embodiments of this application, the magnitude of the sequence numbers of the above - mentioned processes does not mean the order of execution. Some or all of the steps can be executed in parallel or successively. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of this application.

[0028] The terms used in the embodiments of this application are only for the purpose of describing specific embodiments, and are not intended to limit this application. The singular forms "a", "the", and "said" used in the embodiments of this application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0029] The weight of the relevant components mentioned in the specification of the embodiments of this application can not only refer to the specific content of each component, but also represent the proportional relationship of the weights between the components. Therefore, as long as the content of the relevant components in the specification of the embodiments of this application is scaled up or down proportionally, it is within the scope disclosed in the specification of the embodiments of this application. Specifically, the mass mentioned in the specification of the embodiments of this application can be mass units well - known in the chemical industry such as μg, mg, g, kg, etc.

[0030] The terms "first" and "second" are only used for descriptive purposes, to distinguish objects such as substances from each other, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. For example, without departing from the scope of the embodiments of this application, the first XX can also be called the second XX, and similarly, the second XX can also be called the first XX. Thus, the features defined with "first" and "second" can explicitly or implicitly include one or more of such features.

[0031] In a first aspect, the embodiments of this application provide a doping lithium - supplementing additive. The doping lithium - supplementing additive in the embodiments of this application includes lithium - supplementing material particles, and a lithium - supplementing material matrix phase and a doping phase are contained in the crystal phase including the lithium - supplementing material particles.

[0032] Among them, the lithium supplement material base phase contained in the lithium supplement additive particles in the embodiments of the present application. Therefore, its existence can endow the lithium supplement additive in the embodiments of the present application to play the role of lithium supplement. As an additive added to the electrode, it can act as a "sacrificial agent" during the first-cycle charging process, and release all the lithium ions contained in the doped lithium supplement additive at one time as much as possible to improve the first-charge specific capacity of the battery.

[0033] Meanwhile, the lithium supplement material contained in the lithium supplement material base phase can be a conventional lithium supplement material or a newly developed lithium supplement material. In the embodiments, the lithium supplement material can be a ternary lithium supplement material or a binary lithium supplement material. For example, the lithium supplement material can include but is not limited to lithium-rich metal oxides, Li w A, Li 1+a+b Al a M b N c Ti 2-a-b-c (PO4)3, etc.; where 0 < w ≤ 5, A is at least one element selected from C, N, O, P, S, F, B, Se, N is selected from at least one of Si, Ge, Sn, M is selected from at least one of Sc, Ga, Y, La, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.5, 0 ≤ a + b ≤ 0.5. In a specific embodiment, the lithium supplement material of the lithium supplement material base phase can be a nickel-based lithium supplement material, such as including Li2Ni 1-x M x O2, where 0 ≤ x < 1, and M includes at least one of Cu, Mn, Co, Mg, Al. In a specific embodiment, Li2Ni 1-x M x O2 can be Li2NiO2, Li2Ni 1-x Cu x O2, Li2Ni 0.5 Mn 0.5 O2, etc. In some other specific embodiments, the lithium supplement material can also include but is not limited to chemical formulas such as Li2MnO2, Li6MnO4, jLiFeO2·kLi2O·lM d O e , Li6CoO4, Li2NiO2, Li4SiO4, Li2S, Li3N, Li8SnO6, Li 1.3 Al 0.3 Ti 1.7 (PO4)3, etc. Among them, the chemical formula jLiFeO2·kLi2O·lQ d O ewhere j + k ≥ 0.98, l ≤ 0.02, 1.8 ≤ k / j ≤ 2.1, 1 ≤ e / d ≤ 2.5, and Q is at least one of Ni, Co, Mn, Ti, Al, Cu, V, and Zr. These lithium supplement materials are rich in lithium and can release lithium ions during the first-cycle charging process to play an effective lithium supplement role.

[0034] In the examples, the lithium supplement material matrix phase can be at least one of primary particles and secondary particles. The D50 particle size of the lithium supplement material matrix phase can be 0.1 - 30 μm. For example, when the lithium supplement material matrix phase is primary particles, the D50 particle size of the primary particles is 50 - 300 nm; when the lithium supplement material matrix phase is secondary particles, the D50 particle size of the secondary particles is 0.3 - 30 μm, and further can be 1 - 30 μm. Among them, secondary particles refer to agglomerated particles formed by aggregation of more than one primary particle. By controlling the particle size of the lithium supplement material matrix phase, on the basis of its ability to provide abundant lithium ions, the processability of the doped lithium supplement additive in the preparation of lithium battery slurry is improved. Among them, smaller primary particle sizes can also release more lithium.

[0035] In the examples of this application, the doped phase contained in the lithium supplement material particles of the doped lithium supplement additive and the lithium supplement material matrix phase together constitute the crystal phase of the lithium supplement material particles, which can play synergistic effects such as lithium supplement effect and structural stability with the lithium supplement material matrix phase. Specifically, this doped phase can not only offset the loss of active lithium caused by the formation of the SEI film, alleviate the irreversible capacity loss in the first cycle, thereby improving the total capacity and energy density of the battery; but also at least in the form of crystal phase doping, reduce the internal strain of the doped lithium supplement additive crystal, inhibit the formation of harmful microcracks in the doped lithium supplement additive crystal, improve the structural stability of the doped lithium supplement additive crystal, and thus improve the cycle stability of the doped lithium supplement additive.

[0036] In a further example, at least one of the metal oxide, metal carbide, and the compound formed by the metal contained in the metal oxide with lithium and oxygen is also distributed in and / or on the surface layer of the lithium supplement material particles. Further distributing at least one of these metal oxides, metal carbides, and the compound formed by the metal contained in the metal oxide with lithium and oxygen in and / or on the surface layer of the lithium supplement material particles can improve the synergistic effect with the doped phase of the lithium supplement material particles, improve the structural stability of the lithium supplement material particles, and effectively reduce the change in the unit cell volume of the lithium supplement material particles. Moreover, it can also play a protective role and improve the lithium supplement effect of the lithium supplement material matrix phase. Among them, when the metal element contained in the metal oxide, metal carbide, and the compound formed by the metal contained in the metal oxide with lithium and oxygen is denoted as A, then the metal oxide can be denoted as A - O, the metal carbide can be denoted as AC, and the compound formed by the metal contained in the metal oxide with lithium and oxygen can be denoted as Li - O - A.

[0037] In a further embodiment, when at least one of metal oxides, metal carbides, and compounds formed by metals contained in metal oxides with lithium and oxygen is distributed on the surface of the lithium supplement material particles, the at least one of metal oxides, metal carbides, and compounds formed by metals contained in metal oxides with lithium and oxygen forms a coating layer on the surface of the lithium supplement material particles. Controlling the formation of the coating layer of at least one of metal oxides, metal carbides, and compounds formed by metals contained in metal oxides with lithium and oxygen on the surface of the lithium supplement material particles can, on the one hand, play the role of a protective functional layer, improving the electrochemical stability and structural stability of the lithium supplement material matrix phase and the doped phase in the crystal phase of the lithium supplement material particles; on the other hand, it can also play a synergistic effect with the doped phase in the crystal phase of the lithium supplement material particles, especially the metal oxides in the doped phase, improving the above effects of the doped phase itself and the doped phase itself with the lithium supplement material matrix phase, further improving the crystal structure stability of the lithium supplement material particles, such as effectively reducing the change in the unit cell volume of the lithium supplement material particles to further improve the cycle stability of the doped lithium supplement additive. Moreover, it can also enhance the function of isolating the lithium supplement material particles from the environment, improving the stability, processability, and storage performance of the lithium supplement effect of the doped lithium supplement additive.

[0038] In some other embodiments, the metal contained in the metal carbide or metal oxide forms a compound with lithium and oxygen, and the atomic radius of the metal element contained in the metal oxide is greater than or equal to the atomic radius of the metal element contained in the matrix phase of the lithium supplement material. In a specific embodiment, the metal contained in the metal carbide or metal oxide that forms a compound with lithium and oxygen may include at least one of W, Cu, Mg, Sn, Al, Zr, Ti, Ce, Sb, Mo, Y, and further may include at least one of W, Cu, Sn, Sb, Mo. By controlling and optimizing the content and type of the metal contained in the metal carbide or metal oxide that forms a compound with lithium and oxygen, the above-mentioned synergistic effect between the doped phase, specifically the metal oxide, and the matrix phase of the lithium supplement material can be improved, or the synergistic effect between the metal carbide or metal oxide that forms a compound with lithium and oxygen, the metal oxide, and the doped phase in the surface layer and surface distribution can be further improved, thereby improving the lithium supplement effect of the lithium supplement material particles and the stability of the crystal structure, and further improving the cycle stability of the doped lithium supplement additive. Further, for the selection and control of these metal elements, when the atomic radius of these metal elements is similar to or larger than the atomic radius of the metal element contained in the matrix phase of the lithium supplement material, such as Ni element, the structural stability of the lithium supplement material particles can be improved, such as reducing the change in the unit cell volume of the lithium supplement material particles. When the metal carbide or metal oxide that forms a compound with lithium and oxygen forms a coating layer on the surface of the lithium supplement material particles, the coating layer formed by the metal carbide or metal oxide that forms a compound with lithium and oxygen is more uniform on the surface of the lithium-rich material and has a stronger binding force, thereby improving the electrochemical performance of the doped lithium supplement additive of the present application, or further improving the stability, processability, and storage performance of the lithium supplement effect of the doped lithium supplement additive.

[0039] Based on the types of metal elements contained in the lithium supplement material particles of the above metal oxide and the types of lithium supplement materials contained in the lithium supplement material matrix, in the embodiments, the metal element includes W, that is, the doped phase is a tungsten-containing doped phase or further, tungsten oxide, which is the metal oxide, is also distributed in and / or on the surface layer of the lithium supplement material particles. At this time, the lithium supplement material of the lithium supplement material matrix is a nickel-based lithium supplement material. Then, the molar ratio of W to Ni contained in the nickel-based lithium supplement material is controlled to be x:(1 - x), where 0 < x < 1. Further, it can be 0.005 ≤ x ≤ 0.05. Specifically, x can be typical but non-limiting values such as 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.045, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, etc. The above synergistic effect between the tungsten-containing doped phase and the nickel-based lithium supplement matrix is more significant, improving the lithium supplement effect of the doped lithium supplement additive and the stability of the crystal structure, thereby further improving the cycle stability of the doped lithium supplement additive.

[0040] In the embodiments, the mass content of the metal carbide, the metal and lithium and oxygen forming a compound contained in the metal oxide, and the metal oxide in the lithium supplement material particles can be 0.005 - 15%. By optimizing the content of the doped phase or the metal carbide, the metal and lithium and oxygen forming a compound contained in the metal oxide, and the metal oxide distributed on or / and in the surface layer of the lithium supplement material particles, their effects as described above can be improved.

[0041] In the embodiments, the D50 particle size of the doped phase is 0.02 - 3 μm. By controlling the particle size of the doped phase, the doped phase can play its doping role in the lithium supplement material particles of the above doped lithium supplement additives, improve the lithium supplement effect of the lithium supplement material particles and the stability of the crystal structure, and at the same time, control and adjust the particle size of the lithium supplement material particles together with the lithium supplement material matrix. For example, in the embodiments, the D50 particle size of the above lithium supplement material particles is 0.3 - 30 μm.

[0042] In addition, although the lithium supplement material particles of the doping lithium supplement additives in the above embodiments are rich in lithium, they are unstable in the presence of water and carbon dioxide, and are prone to react with water and carbon dioxide, resulting in a reduction in the lithium supplement effect, processing performance, and storage stability of the doping lithium supplement additives in the embodiments of the present application. For example, it may cause a sharp increase in the viscosity of the slurry containing the above doping lithium supplement additives, and quickly gel and lose fluidity, making subsequent processing impossible. Therefore, based on the doping lithium supplement additives in the above embodiments, a sealing functional coating layer is further included on the outer surface of the lithium supplement material particles of the doping lithium supplement additives in the above embodiments, that is, the sealing functional coating layer coats the lithium supplement material particles of the doping lithium supplement additives in the above embodiments. In this way, by adding the sealing functional coating layer, the related properties of the lithium supplement material particles of the doping lithium supplement additives in the embodiments of the present application can be improved, such as properties including electronic conductivity and / or ionic conductivity, thereby improving the electrical conductivity or the lithium ion conduction performance of the doping lithium supplement additives in the embodiments of the present application. It can also isolate the action of the external environment, improve the lithium supplement effect, processing, storage and other properties, thereby improving the electrochemical properties such as specific capacity of the doping lithium supplement additives in the embodiments of the present application. In the embodiment, the thickness of the sealing functional coating layer is 2-60 nm. By adjusting the thickness of the sealing functional coating layer, the coating effect of the sealing functional coating layer on the doping lithium supplement additives in the above embodiments can be improved, and its delithiation efficiency can be ensured. Of course, when there is at least one of metal carbide, a compound formed by the metal contained in the metal oxide with lithium and oxygen, and the metal oxide on the surface of the lithium supplement material particles contained in the above doping lithium supplement additives and a coating layer is formed, the sealing functional coating layer may not be provided. In the embodiment, the sealing functional coating layer may be an electronic conductor coating layer, an ionic conductor coating layer, or a composite layer structure formed by an electronic conductor coating layer and an ionic conductor coating layer. When the sealing functional coating layer contains both an electronic conductor coating layer and an ionic conductor coating layer, the electronic conductor coating layer or the ionic conductor coating layer coats the lithium carbonate coating layer.

[0043] When the sealing functional coating layer contains an electronic conductor coating layer, the electronic conductor coating layer can enhance the electronic conductivity of the sealing functional coating layer, thereby enhancing the electronic conductivity of the doping lithium supplement additives, which is beneficial to reducing the impedance inside the electrode; at the same time, during and after the release process of the doping lithium supplement additives as a "sacrificial agent", the electronic conductor coating layer can be reused and play an auxiliary role as a conductive agent inside the electrode. In the embodiment, the thickness of the above electronic conductor coating layer can be 0.5-100 nm, further 1-50 nm, and even further 2-20 nm. In other embodiments, the mass content of the electronic conductor coating layer in the doping lithium supplement additives is 0.1-30%, further 0.1-10%, and more preferably 0.5-5%.

[0044] In the embodiment, the material of the above-mentioned electronic conductor coating layer includes at least one of carbon materials and conductive oxides. In a specific embodiment, the carbon materials include at least one of amorphous carbon, carbon nanotubes, graphite, carbon black, graphene, etc. In a specific embodiment, the conductive oxides may include at least one of In2O3, ZnO, and SnO2. By adjusting the thickness and material of the electronic conductor coating layer, its electronic conductivity can be further improved.

[0045] When the sealing functional coating layer contains an ionic conductor coating layer, the ionic conductor coating layer can enhance the ionic conductivity of the functional encapsulation, thereby enhancing the ionic conductivity of the doping lithium supplement additive, facilitating the outward transport of lithium ions of the doping lithium supplement additive, improving the detachment efficiency of the doping lithium supplement additive, and improving the lithium supplement effect of the doping lithium supplement additive. At the same time, when the doping lithium supplement additive releases all its lithium ions as a "sacrificial agent", the ionic conductor coating layer can be reused and play an auxiliary role in enhancing ion transport inside the electrode. In the embodiment, the thickness of the ionic conductor coating layer can be 1 - 200 nm, further 1 - 50 nm, and still further 2 - 20 nm. In another embodiment, the material of the ionic conductor coating layer includes at least one of perovskite type, NASICON type, and garnet type. In a specific embodiment, the perovskite type includes Li 3x La 2 / 3- x TiO3 (LLTO), specifically such as Li 0.5 La 0.5 TiO3, Li 0.33 La 0.57 TiO3, Li 0.29 La 0.57 TiO3, Li 0.33 Ba 0.25 La 0.39 TiO3, (Li 0.33 La 0.56 ) 1.005 Ti 0.99 Al 0.01O3 、Li 0.5 La 0.5 Ti 0.95 Zr 0.05 O3, etc. At least one of them, the NASICON type is such as but not limited to Li 1.4 Al 0.4 Ti 1.6 (PO4)3 (LATP), the garnet type includes Li7La3Zr2O 12 (LLZO), Li 6·4 La3Zr 1·4 Ta 0·6 O 12 , Li 6.5 La3Zr1.5 Ta 0.5 O 12 At least one of them. By adjusting the thickness and material of the ion conductor coating layer 23, its ionic conductivity can be further improved.

[0046] In addition, according to needs, other layer structures may also be included on the outer surface of the sealing functional coating layer. For example, it may include, but is not limited to, coating layers such as conductive organic substances, and form a composite coating layer structure with at least one of the above-mentioned electron conductor coating layer and ion conductor coating layer. For example, when the other coating layer includes a conductive organic substance coating layer, the conductive organic substance coating layer is coated on the outer surfaces of the electron conductor coating layer and the ion conductor coating layer.

[0047] Based on the above embodiments, after testing, the doping lithium supplement additive of the embodiments of the present application also has excellent electrochemical properties, etc. For example, the first charge specific capacity of the doping lithium supplement additive is above 450 mAh / g, such as 450 m - 470 mAh / g, the reversible capacity of the doping lithium supplement additive is above 150 mAh / g, such as 150 m - 160 mAh / g, the BET specific surface area of the doping lithium supplement additive is 0.1 - 50 m 2 / g, and the purity of the doping lithium supplement additive is 75 - 99%.

[0048] In the second aspect, the embodiments of the present application also provide a preparation method of the above-mentioned doping lithium supplement additive. The process flow of the preparation method of the doping lithium supplement additive in the embodiments of the present application is as Figure 1 shown, including the following steps:

[0049] S01: Provide a lithium supplement material precursor containing a doping element;

[0050] S02: Mix the lithium supplement material precursor with a lithium source to obtain a precursor mixture;

[0051] S03: Sinter the precursor mixture in a protective atmosphere to obtain a doping lithium supplement additive.

[0052] Among them, the lithium supplement material precursor containing a doping element in step S01 is the precursor for forming the lithium supplement material particles contained in the above-mentioned doping lithium supplement additive. Therefore, the doping element contained in the lithium supplement material precursor is at least used to form a doping phase, or further used to form a metal oxide coating layer distributed in and / or on the surface layer of the lithium supplement material particles contained in the above-mentioned doping lithium supplement additive. Moreover, in the lithium supplement material precursor, the types and proportions of the doping element and the elements used to form the lithium supplement material can be in accordance with the types and proportions of the lithium supplement material matrix phase and doping phase contained in the above-mentioned doping lithium supplement material particles, or further distributed in the surface layer of the lithium supplement material particles and / or the types and proportions of the metal oxides on the surface.

[0053] In an embodiment, the prelithiation material precursor containing a doping element can be prepared by any one of the coprecipitation method and the sol-gel method. For example, if the prelithiation material precursor containing a doping element is a nickel-based prelithiation material precursor doped with tungsten, it is prepared by a preparation method including the following:

[0054] S011: Mix a NaOH solution including a nickel source, NH4OH, and WO3 to obtain a mixed solution;

[0055] S012: Heat-treat the mixed solution and perform a precipitation reaction to generate a nickel-based prelithiation material precursor doped with tungsten.

[0056] In one embodiment, the molar ratio of W to Ni contained in the nickel source in S011 can be controlled to be x:(1 - x), where 0 < x < 1, and further can be 0.005 ≤ x ≤ 0.05. In a specific embodiment, the nickel source can be at least one of NiSO4, Ni(NO3)2, NiCO3, or Ni(OH)2. This mixing treatment can be any method that can make each component mix evenly within the scope disclosed in the specification of this application. For example, it can be stirring and mixing. Specifically, the mixing treatment is performed at a stirring speed of 400 - 600 rpm, and the mixing treatment time should be sufficient, such as 10 - 15 h.

[0057] In step S012, the heat treatment and precipitation reaction are to make the nickel source and WO3 react in an alkaline solution to form a precipitate, such as [Ni 1-x W x (OH)2, that is, a nickel-based prelithiation material precursor doped with tungsten. Among them, this heat treatment can be determined according to the conditions for the precipitation reaction of each source. For example, it can be but not limited to 60°C, and the precipitation reaction should be sufficient. After the precipitation reaction ends, the reaction mixture solution can be subjected to solid-liquid separation to obtain a precipitate. Subsequent treatments such as washing and drying can also be performed on the precipitate.

[0058] In step S02, in the mixing treatment of the prelithiation material precursor and the lithium source, the lithium source can be appropriately excessive. Ideally, it is mixed according to the molar stoichiometric ratio of each element in the prelithiation material particles contained in the above-mentioned doped prelithiation additive. For example, in an embodiment, the molar ratio of the lithium source to the prelithiation material precursor can be 2 - 2.2:1. In a specific embodiment, the lithium source can be at least one of LiOH·H2O, LiCO3, or LiCl, etc.

[0059] During the sintering process in step S03, the lithium supplement material precursor and the lithium source are sintered to form the lithium supplement material particles contained in the doped lithium supplement additive in the above embodiments of the present application. During the sintering process, the doping elements contained in the lithium supplement material precursor are sintered to form a metal oxide doped phase, and the doping elements in and / or on the surface layer of the lithium supplement material precursor are sintered to form metal oxides. In particular, the doping elements on the surface of the lithium supplement material precursor can be sintered to form a metal oxide coating layer, which plays a protective role.

[0060] The temperature of this sintering process can be specifically controlled according to the type and sintering performance of the precursor. For example, it can be controlled to be 600 - 850 °C. The temperature of this sintering process can enable the precursor and the lithium source to be fully sintered, reduce the content of impurities such as residual alkali, and improve the purity of the generated doped lithium supplement additive. The sintering time should be sufficient. For example, it can be controlled to hold for 5 - 15 h at 600 - 850 °C. By controlling and optimizing the sintering time, on the premise of ensuring sufficient sintering, it is beneficial to control the crystal form of the doped lithium supplement additive to improve the electrochemical performance of the doped lithium supplement additive.

[0061] In the embodiment, the protective atmosphere can be an inert atmosphere, such as an atmosphere of nitrogen or argon.

[0062] In addition, after step S03, according to the requirements, other layer structures can be further formed on the surface of the doped lithium supplement additive generated by the sintering process in step S03. For example, the other layer structures can be the electronic conductor encapsulation layer and the ion conductor encapsulation layer contained in the doped lithium supplement additive in the above embodiments of the present application, or can also be a coating layer including conductive organic substances, etc. When the other coating layer includes a conductive organic substance coating layer, the conductive organic substance coating layer is coated on the outer surface of the electronic conductor encapsulation layer or the ion conductor encapsulation layer. The formation method can also be formed by in-situ mixing treatment, spray drying and other methods.

[0063] In the embodiment, during the process of further forming other layer structures on the surface of the doped lithium supplement additive generated by the sintering process in step S03, if the environment contains a carbon source, then during processes such as the sintering process, while the carbon source forms a sealing functional coating layer, the generated carbon can further react with the residual alkali on the surface of the lithium supplement material particles, such as lithium oxide, etc., to generate a lithium - oxygen - doped metal compound (such as Li - O - A above), or the generated carbon reacts with the doped metal element to generate a metal carbide (such as AC above). Moreover, these Li - O - A, AC, etc. generated on the surface can also cause the metal doping elements to diffuse into the surface layer of the lithium supplement material particles through thermal diffusion in the process.

[0064] Therefore, the above preparation method of the doped lithium supplement additive can effectively prepare the doped lithium supplement additive with metal oxide doping in the above application embodiment, endowing the prepared doped lithium supplement additive with excellent lithium supplement effect, stable crystal structure and cycling performance. Or further, a core-shell structure doped lithium supplement additive with a sealing functional coating layer can be prepared, endowing the doped lithium supplement additive with excellent processing performance and storage performance. Moreover, by controlling the types and content ratios of each component, the content of metal oxide and the like can be adjusted to optimize the corresponding electrochemical performance of the doped lithium supplement additive. In addition, the preparation method of the doped lithium supplement additive can ensure the stability of the structure and electrochemical performance of the prepared doped lithium supplement additive, with high efficiency and cost savings in production.

[0065] In a third aspect, the embodiments of the present application further provide an electrode. The electrode in the embodiments of the present application includes a current collector and an electrode active layer combined on the surface of the current collector, and the electrode active layer contains the doped lithium supplement additive in the above application embodiment. Since the electrode in the embodiments of the present application contains the above-mentioned doped lithium supplement additive in the embodiments of the present application, therefore, the first charge specific capacity of the electrode in the embodiments of the present application is high, and the cycling performance is high, the service life is long, and the energy density is high.

[0066] In one embodiment, the mass content of the doped lithium supplement additive contained in the electrode active layer can be 0.1-15%; preferably, 1-10%. In addition to the doped lithium supplement additive, the electrode active layer further includes an electrode active material, a binder, and a conductive agent. Among them, the binder can be a commonly used electrode binder, such as including one or more of polyvinylidene chloride, soluble polytetrafluoroethylene, styrene-butadiene rubber, hydroxypropyl methylcellulose, methylcellulose, carboxymethylcellulose, polyvinyl alcohol, acrylonitrile copolymer, sodium alginate, chitosan, and chitosan derivatives. In the embodiments of the present application, the conductive agent can be a commonly used conductive agent, such as including one or more of graphite, carbon black, acetylene black, graphene, carbon fiber, C60, and carbon nanotubes. The electrode active material, such as the positive electrode active material, can include one or more of lithium cobaltate, lithium manganate, lithium iron phosphate, lithium vanadium phosphate, lithium vanadium oxyphosphate, lithium fluorovanadate phosphate, lithium titanate, lithium nickel cobalt manganate, and lithium nickel cobalt aluminate.

[0067] In the embodiment, the electrode preparation process can be: mixing the electrode active material, the doped lithium supplement additive, the conductive agent, and the binder to obtain an electrode slurry, coating the electrode slurry on the current collector, and preparing the electrode through steps such as drying, rolling, and die-cutting.

[0068] Fourthly, an embodiment of the present application further provides a secondary battery. The secondary battery of the embodiment of the present application includes necessary components such as a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte, and of course, other necessary or auxiliary components. Among them, the positive electrode sheet may be the electrode of the embodiment of the present application above, that is, the positive electrode active layer contained in the positive electrode sheet contains the doping lithium supplement additive of the embodiment of the present application above.

[0069] Since the secondary battery of the embodiment of the present application contains the doping lithium supplement additive of the embodiment of the present application above, based on the excellent lithium supplement performance of the doping lithium supplement additive of the embodiment of the present application above, or further having ionic conductivity and / or electronic conductivity, the first charge specific capacity, battery capacity, and cycle performance of the secondary battery of the embodiment of the present application are given, with a long service life and stable electrochemical performance.

[0070] The following uses multiple specific examples to illustrate the doping lithium supplement additive of the embodiment of the present application, its preparation method, application, etc.

[0071] 1. Embodiment of the doping lithium supplement additive and its preparation method:

[0072] Example A1

[0073] This example provides a doping lithium supplement additive and its preparation method. The doping lithium supplement additive is Li2Ni 0.99 W 0.01 O2.

[0074] The preparation method of the doping lithium supplement additive in this example includes the following steps:

[0075] S1: Pump the aqueous solution of NiSO4 into the mixed solution of NH4OH and NaOH containing WO3, and stir at 60 °C to obtain a tungsten-doped precursor of the doping lithium supplement additive [Ni 1-x W x (OH)2 (x = 0.01);

[0076] S2: Mix the lithium source and the precursor of the doping lithium supplement additive in step S1 evenly according to a molar ratio of 2.0:1, and then perform sintering treatment at 700 °C for 10 h under the protection of an inert atmosphere of nitrogen and then naturally cool to finally obtain the tungsten-doped lithium-rich cathode material Li2Ni 0.99 W 0.01 O2.

[0077] After testing, the D50 particle size of the doping lithium supplement additive is 1.5 μm, the BET specific surface area is 0.4 m 2 / g, and the purity is 95%.

[0078] Example A2

[0079] This embodiment provides a doped lithium - supplementing additive and a preparation method thereof. The doped lithium - supplementing additive is Li2Ni 0.96 W 0.04 O2.

[0080] The difference between this embodiment and Embodiment A1 is only that the tungsten - doped precursor of the doped lithium - supplementing additive in step S1 is [Ni 1-x W x (OH)2(x = 0.04), and other conditions and parameters are exactly the same as those in Embodiment A1. After testing, the D50 particle size of the doped lithium - supplementing additive is 1.4 μm, the BET specific surface area is 0.41 m 2 / g, and the purity is 94.2%.

[0081] Embodiment A3

[0082] This embodiment provides a doped lithium - supplementing additive and a preparation method thereof. The doped lithium - supplementing additive includes Li2Ni 0.96 W 0.04 O2, a metal - oxide coating layer, and a dense functional encapsulation layer.

[0083] The preparation method of the doped lithium - supplementing additive in this embodiment includes the following steps:

[0084] S1: Pump an aqueous solution of NiSO4 into a mixed solution of NH4OH and NaOH containing WO3, and stir at 60 °C to obtain a tungsten - doped precursor of the doped lithium - supplementing additive [Ni 1-x W x (OH)2(x = 0.04);

[0085] S2: Mix the lithium source and the precursor of the doped lithium - supplementing additive in step S1 evenly according to a molar ratio of 2.0:1, add 3 wt% glucose, mix them evenly, and perform sintering treatment at 700 °C for 10 h under the protection of an inert nitrogen atmosphere, and then cool naturally to finally obtain a tungsten - doped lithium - rich cathode material with a coated structure Li2Ni 0.99 W 0.04 O2@WO3@WC@C.

[0086] After testing, the D50 particle size of the doped lithium - supplementing additive is 1.4 μm, the BET specific surface area is 0.41 m 2 / g, the purity is 94.2%, and the thickness of the C - coating layer is about 10 nm.

[0087] Embodiment A4

[0088] This embodiment provides a doped lithium - supplementing additive and a preparation method thereof. The doped lithium - supplementing additive includes Li2Ni 0.99 Cu 0.01 O2.

[0089] The preparation method of the doped lithium - supplementing additive in this embodiment includes the following steps:

[0090] S1: Pump the aqueous solution of NiSO4 into the mixed solution of NH4OH and NaOH containing CuO, and stir at 60 °C to obtain the copper - doped precursor of the lithium - supplementing additive [Ni 1-x Cu x (OH)2(x = 0.01);

[0091] S2: Mix the lithium source and the precursor of the doped lithium - supplementing additive in step S1 evenly according to a molar ratio of 2.1:1, then carry out sintering treatment at 730 °C for 8 h under the protection of an inert nitrogen atmosphere, and then cool naturally to finally obtain the tungsten - doped lithium - rich cathode material Li2Ni 0.99 Cu 0.01 O2.

[0092] After detection, the D50 particle size of the doped lithium - supplementing additive is 1.6 μm, the BET specific surface area is 0.42 m 2 / g, and the purity is 96%.

[0093] Example A5

[0094] This embodiment provides a doped lithium - supplementing additive and its preparation method. The doped lithium - supplementing additive includes Li2Ni 0.96 Mo 0.04 O2.

[0095] The difference between this embodiment and Example A3 is only that the molybdenum - doped precursor of the lithium - supplementing additive in step S1 is [Ni 1-x Mo x (OH)2(x = 0.04), and other conditions and parameters are exactly the same as those in Example A3.

[0096] After detection, the finally obtained molybdenum - doped lithium - rich cathode material containing Mo2C is Li2Ni 0.99 Mo 0.04 O2@C.

[0097] The D50 particle size of the doped lithium - supplementing additive is 1.5 μm, the BET specific surface area is 0.43 m 2 / g, and the purity is 95.5%.

[0098] Example A6

[0099] This embodiment provides a doped lithium - supplementing additive and its preparation method. The doped lithium - supplementing additive includes Li2Ni 0.99 Mg 0.01 O2.

[0100] The preparation method of the doped lithium - supplementing additive in this embodiment includes the following steps:

[0101] S1: Pump the aqueous solution of NiSO4 into the mixed solution of NH4OH and NaOH containing MgO, and stir at 60 °C to obtain a magnesium-doped lithium-doped additive precursor [Ni 1-x Mg x (OH)2 (x = 0.01);

[0102] S2: Mix the lithium source and the lithium-doped additive precursor in step S1 evenly according to a molar ratio of 2.1:1, and then perform sintering treatment at 750 °C for 10 h under the protection of an inert atmosphere of nitrogen, followed by natural cooling, and finally obtain a tungsten-doped lithium-rich cathode material Li2Ni 0.99 Mg 0.01 O2.

[0103] After testing, the D50 particle size of the lithium-doped additive is 1.6 μm, the BET specific surface area is 0.42 m 2 / g, and the purity is 93.1%.

[0104] Example A7

[0105] This example provides a lithium-doped additive and a preparation method thereof. The lithium-doped additive includes Li2Ni 0.96 Mg 0.04 O2.

[0106] The difference between this example and Example A6 is only that the magnesium-doped lithium-doped additive precursor described in step S1 is [Ni 1-x Mg x (OH)2 (x = 0.04), and other conditions and parameters are exactly the same as those in Example A6.

[0107] After testing, the D50 particle size of the lithium-doped additive is 1.4 μm, the BET specific surface area is 0.44 m 2 / g, and the purity is 92%.

[0108] Comparative Example A1

[0109] This comparative example provides a lithium supplement additive, which does not contain tungsten, copper, or magnesium doping and does not contain a dense functional encapsulation layer compared with Examples A1-A6.

[0110] The preparation method of the lithium supplement additive in this comparative example includes the following steps:

[0111] S1: Pump the aqueous solution of NiSO4 into the mixed solution of NH4OH and NaOH, and stir at 60 °C to obtain an undoped lithium supplement additive precursor Ni(OH)2;

[0112] S2: Mix the lithium source with the doping lithium supplement additive precursor obtained in step S1, perform sintering treatment at 700 °C for 10 h under the protection of an inert atmosphere of nitrogen, and then perform natural cooling to finally obtain the lithium-rich cathode material Li2NiO2.

[0113] After testing, the D50 particle size of the lithium supplement additive is 1.5 μm, the BET specific surface area is 0.40 m 2 / g, and the purity is 93%.

[0114] 2. Lithium-ion battery examples:

[0115] Examples A1 to A7 and Comparative Example A1 of this embodiment respectively provide a lithium-ion battery. Each lithium-ion battery is assembled into a partial lithium-ion battery according to the following method:

[0116] Positive electrode sheet: Using the positive electrode lithium supplement additives provided in Examples A1 to A7 and Comparative Example A1 as the positive electrode lithium supplement additives of Examples B1 to B7 and Comparative Example B1 of the lithium-ion battery respectively, mix the doping lithium supplement additive and lithium cobaltate in a mass ratio of 5:95 to obtain a mixture, mix the mixture, polyvinylidene fluoride and SP-Li in a mass ratio of 95:3:2, perform ball milling and stirring to obtain a positive electrode slurry, coat the positive electrode slurry on the surface of the aluminum foil, after rolling, perform vacuum drying at 110 °C overnight to obtain the positive electrode sheet;

[0117] Negative electrode: Lithium metal sheet;

[0118] Electrolyte: Ethylene carbonate and ethyl methyl carbonate are mixed in a volume ratio of 3:7, and LiPF6 is added to form an electrolyte, and the concentration of LiPF6 is 1 mol / L;

[0119] Separator: Polypropylene microporous separator;

[0120] Assembly of lithium-ion battery: Assemble the lithium-ion battery in an inert atmosphere glove box according to the assembly order of lithium metal sheet - separator - electrolyte - positive electrode sheet.

[0121] 3. Related performance tests

[0122] 1. Electron microscopy analysis of the doping lithium supplement additive:

[0123] Perform electron microscopy analysis on the doping lithium supplement additives provided in Examples A1 to A7. Among them, the electron micrograph of the doping lithium supplement additive provided in Example A1 is as Figure 2 shown. As can be seen from Figure 2 , for the lithium supplement additive doped with tungsten element in Example A1 of this embodiment, its morphology is granular and blocky, and the morphology is good. The electron micrographs of the doping lithium supplement additives provided in other examples are similar to Figure 2 . Therefore, the doping lithium supplement additives provided in the examples of this application have uniform particle size and stable morphology.

[0124] 2. XRD Analysis of Doped Lithium-Compensating Additive:

[0125] The doped lithium-compensating additives provided in Examples A1 to A7 were subjected to XRD test analysis. Among them, the XRD pattern of the molybdenum-doped lithium-compensating additive provided in Example A5 is as Figure 4 shown. It can be seen from Figure 4 that there are characteristic diffraction peaks of a small amount of Mo2C in the lithium-rich cathode material Li2Ni 0.99 Mo 0.04 O2. This indicates that when using metal oxide to dope the lithium-rich cathode material, the metal oxide will react with the carbon source to generate molybdenum carbide.

[0126] 3. Examples of Lithium-Ion Batteries:

[0127] The electrochemical performances of the lithium-ion batteries assembled in the above lithium-ion battery examples were tested under the following conditions:

[0128] The coin cell was charged at a constant current and voltage of 0.05C to 4.3V with a cut-off current of 0.02C, rested for 5 min, discharged at a rate of 0.05C to 2.8V, and then charged at a constant current and voltage of 0.2C to 4.3V with a cut-off current of 0.02C, rested for 5 min, and discharged at a rate of 0.2C to 2.8V, for 100 cycles.

[0129] The test results are shown in Table 1 below. Among them, the first charge-discharge curve of the lithium-ion battery provided in Example B1 is as Figure 3 shown:

[0130] Table 1

[0131]

[0132]

[0133] From Table 1 combined with Figure 3It can be seen that the initial charge specific capacity of the control group without the lithium supplement additive is only 149.1 mAh / g. However, the initial charge specific capacity values of the lithium batteries containing the lithium supplement additive doped with other metals in Examples B1 - B7 are all above 166 mAh / g, and the increase in specific capacity is also above 17 mAh / g. The capacity retention rate after 100 cycles is also above 88%. In Example B3, due to the simultaneous presence of a metal oxide coating layer, a WC layer, and a C layer, its initial charge specific capacity is higher than that of other examples. At the same time, it can be observed that for Comparative Example B1 with the lithium supplement additive without doped metal provided by Comparative Example A1, its initial charge specific capacity is only 160 mAh / g, the increase in specific capacity is only 10.9 mAh / g, and after 100 cycles at a 0.2C rate, the capacity retention rate only remains at about 85%. This shows that in the examples of the present application, doping with low-cost metal elements as precursors for coprecipitation of metals can not only reduce the cost of lithium batteries, but also replace a part of Ni 2+ , reduce the mixing of lithium and nickel, improve the stability of the crystal structure of the doped lithium supplement additive, and thus improve the cycle stability of the doped lithium supplement additive.

[0134] The above examples only represent several implementation manners of the present application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A lithium-doped lithium supplement additive, characterized in that: It includes lithium - supplementing material particles. In the crystal phase of the lithium - supplementing material particles, there are a lithium - supplementing material matrix phase and a doping phase. The doping phase includes metal oxides. The lithium - supplementing material particles are formed by sintering a mixture of a lithium - supplementing material precursor containing doping elements and a lithium source in a protective atmosphere; On the surface layer and the surface of the lithium - supplementing material particles, there is also at least one of metal carbides, a compound formed by the metal contained in the metal oxides with lithium and oxygen; At least one of metal carbides, a compound formed by the metal contained in the metal oxides with lithium and oxygen, which are distributed on the surface of the lithium - supplementing material particles, forms a coating layer; The total mass content of the metal carbides, a compound formed by the metal contained in the metal oxides with lithium and oxygen, and the metal oxides in the lithium - supplementing material particles is 0.005 - 15%; 2. The lithium-doped lithium supplement additive according to claim 1, characterized in that: The lithium supplementing material of the lithium supplementing material matrix phase includes at least one of lithium-rich metal oxide, Li w A, Li 1+a+b Al a M b N c Ti 2-a-b-c (PO4)3; where 0 < w ≤ 5, A is at least one element of C, N, O, P, S, F, B, Se, N is at least one of Si, Ge, Sn, M is selected from at least one of Sc, Ga, Y, La, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.5, and at least one of 0 ≤ a + b ≤ 0.

5.

3. The lithium-doped lithium supplement additive according to any one of claims 1-2, characterized in that: The metal element contained in the metal carbides, a compound formed by the metal contained in the metal oxides with lithium and oxygen, and the metal oxides has an atomic radius greater than or equal to the atomic radius of the metal element contained in the lithium - supplementing material matrix phase; and / or The metal element contained in the metal carbides, a compound formed by the metal contained in the metal oxides with lithium and oxygen, and the metal oxides is the same or different and includes at least one of W, Cu, Mg, Sn, Al, Zr, Ti, Ce, Sb, Mo, Y; 4. The lithium-doped lithium supplement additive according to claim 3, characterized in that: The metal element contained in the metal carbides, a compound formed by the metal contained in the metal oxides with lithium and oxygen, and the metal oxides includes W. The lithium - supplementing material of the lithium - supplementing material matrix phase is a nickel - based lithium - supplementing material, and the molar ratio of W to Ni contained in the nickel - based lithium - supplementing material is x:(1 - x), where 0 < x < 1; 5. The lithium-doped lithium supplement additive according to any one of claims 1-2 and 4, characterized in that: The D50 particle size of the lithium - supplementing material matrix phase is 0.1 - 30 µm; and / or The D50 particle size of the doping phase is 0.02 - 3 µm; and / or The D50 particle size of the lithium - supplementing material particles is 0.3 - 30 µm.

6. The lithium-doped lithium supplement additive according to any one of claims 1-2 and 4, characterized in that: The doped lithium - supplementing additive further includes a sealing functional coating layer, and the sealing functional coating layer coats the lithium - supplementing material particles.

7. The lithium-doped lithium supplement additive according to claim 6, characterized in that: The thickness of the sealing functional coating layer is 1 - 100 nm; and / or The material of the sealing functional coating layer includes a sealing functional coating layer with ionic conductivity or / and electronic conductivity.

8. The lithium-doped lithium supplement additive according to any one of claims 1-2, 4, and 7, characterized in that: The first - charge specific capacity of the doped lithium - supplementing additive is more than 450 mAh / g; and / or The reversible capacity of the doped lithium - supplementing additive is more than 150 mAh / g; and / or The BET specific surface area of the doped lithium supplement additive is 0.1 - 50 m 2 / g; and / or The purity of the doped lithium - supplementing additive is 75 - 99%.

9. The preparation method of the lithium-doped lithium supplement additive according to any one of claims 1-8, characterized in that, It includes the following steps: Provide a lithium - supplementing material precursor containing doping elements; wherein, the doping elements are at least used to form a doping phase; Mix the lithium - supplementing material precursor and a lithium source to obtain a precursor mixture; In a protective atmosphere, sinter the precursor mixture to obtain a doped lithium - supplementing additive.

10. The preparation method according to claim 9, characterized in that, The lithium - supplementing material precursor containing doping elements is obtained by any one of the co - precipitation method and the sol - gel method; and / or The temperature of the sintering treatment is 600 - 850 °C; and / or It further includes the step of forming a sealing functional coating layer on the surface of the doped lithium supplement additive obtained through the sintering treatment.

11. The preparation method according to claim 9 or 10, characterized in that, The lithium supplement material precursor containing doped elements is a nickel-based lithium supplement material precursor doped with tungsten, and is obtained by a preparation method including the following: A NaOH solution including a nickel source, NH4OH, and WO3 is subjected to a mixing treatment to obtain a mixed solution; wherein, the molar ratio of W to Ni contained in the nickel source is x: (1 - x), where x is 0 < x < 1; The mixed solution is heat-treated and subjected to a precipitation reaction to generate the nickel-based lithium supplement material precursor doped with tungsten.

12. An electrode includes a current collector and an electrode active layer bonded to the surface of the current collector, characterized in that: The active layer contains the doped lithium supplement additive according to any one of claims 1-8 or the doped lithium supplement additive prepared by the preparation method according to any one of claims 9-11.

13. A secondary battery, characterized in that: It includes the electrode according to claim 12.

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