Lithium ion battery and preparation method thereof, and electric device

Abstract

The embodiment of the application discloses a lithium ion battery, a preparation method thereof and an electric device. The lithium ion battery comprises a negative electrode sheet, a negative electrode active material layer of the negative electrode sheet comprises a lithiumophilic metal, and an electrolyte, the electrolyte comprises metal ions, and a reduction potential of the metal ions is higher than that of lithium ions. The lithiumophilic metal and the metal ions in the lithium ion battery can continuously inhibit lithium dendrites in a long cycle process, and effectively improve the cycle performance and service life of the lithium ion battery.

Description

Technical Field

[0001] This application relates to the field of batteries, and more specifically, to a lithium-ion battery and its preparation method and electrical device. Background Technology

[0002] In recent years, lithium-ion batteries have been widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power plants, as well as in many fields such as power tools, electric bicycles, electric motorcycles, electric cars, military equipment, and aerospace, thus achieving great development.

[0003] Lithium dendrites are one of the factors affecting the performance of lithium-ion batteries. The growth of lithium dendrites leads to reduced coulombic efficiency and poor cycle performance, and in severe cases, can puncture the separator, causing a short circuit. Therefore, how to suppress the growth of lithium dendrites is a technical problem that urgently needs to be solved. Summary of the Invention

[0004] This application is made in view of the above-mentioned technical problems, and its purpose is to provide a lithium-ion battery, a method for preparing the same, and an electrical device thereof. This lithium-ion battery has a designed negative electrode and electrolyte, which can effectively improve lithium deposition during battery cycling, thereby suppressing lithium dendrite formation.

[0005] In a first aspect, a lithium-ion battery is provided, the lithium-ion battery comprising: a negative electrode sheet, the negative electrode sheet having a negative electrode active material layer comprising a lithium-philic metal; and an electrolyte comprising metal ions, the metal ions having a reduction potential higher than that of lithium ions.

[0006] It should be understood that lithium-loving metals are elemental metals that can form alloys with lithium.

[0007] In the embodiments of this application, the negative electrode of the lithium-ion battery contains a lithiophilic metal, and the electrolyte contains metal ions. The lithiophilic metal can form a lithium-metal alloy with lithium when lithium plating occurs at the negative electrode. The reduction potential of the metal corresponding to the metal ions is higher than the reduction potential of lithium. During lithium plating at the negative electrode, the metal ions can be reduced to elemental metals by lithium, consuming the deposited lithium. Therefore, by using a negative electrode containing a lithiophilic metal and an electrolyte containing metal ions, the lithium plating problem during lithium-ion battery cycling can be effectively improved, thereby suppressing the generation and / or growth of lithium dendrites. Furthermore, through the combined action of the lithiophilic metal and metal ions, continuous suppression of lithium dendrites can be achieved during long-term cycling of the lithium-ion battery, thereby helping to improve the cycle performance and lifespan of the lithium-ion battery.

[0008] In one possible implementation, the lithium-loving metal is located on the surface of the negative electrode active material layer near the electrolyte.

[0009] Lithium plating typically occurs on the surface of the negative electrode active material layer. In embodiments of this application, by placing a lithium-philic metal on the surface of the negative electrode active material layer near the electrolyte, it helps to promptly consume the deposited lithium when lithium plating occurs at the negative electrode, thereby more effectively improving lithium plating and suppressing lithium dendrite formation.

[0010] In one possible implementation, the lithium-loving metal includes at least one of Mg, Sn, Ag, Al, In, Zn, Ca, Sr, Ba, Sc, Y, Rh, Ir, Pd, Pt, Au, Cd, Ga, Ge, Pb, Sb, and Bi.

[0011] In one possible implementation, the content w1 of the lithium-loving metal in the negative electrode sheet satisfies: 100ppm≤w1≤1000ppm.

[0012] The content of lithiophilic metals in the negative electrode affects both the suppression of lithium dendrites and the impedance of the battery. In the embodiments of this application, by controlling the content of lithiophilic metals within a suitable range, it is helpful to improve the impedance of the lithium-ion battery while suppressing lithium dendrites.

[0013] In one possible implementation, the lithium-loving metal comprises single atoms and / or particles, the size d of which satisfies: 0 nm < d ≤ 3 nm.

[0014] When the negative electrode active material layer contains a lithium-philic metal, the lithium-philic metal has a certain influence on the physicochemical properties of the SEI film formed on the surface of the negative electrode active material layer. In the embodiments of this application, by controlling the particle size of the lithium-philic metal within a suitable range, the possibility of excessive self-discharge of the lithium-ion battery due to the inability of the SEI film to provide insulation can be reduced, thereby helping to improve the service life of the lithium-ion battery.

[0015] In one possible implementation, the SEI film of the negative electrode includes at least one of the lithium-philic metal fluoride and carbonate.

[0016] In one possible implementation, the metal ions include Mg. 2+ Sn 4+ Ag + Al 3+ In 3+ Zn 2+ Ca 2+ 、Sr 2+ Ba 2+ ,Sc + Y 3+ ,Rh 3+ Ir 3+ Pd 3+ Pt 3+ Au 2+ Cd2+ Ga 3+ 、Ge 4+ Pb 4+ Sb 3+ Bi 3+ At least one of them.

[0017] In one possible implementation, the content w2 of the metal ions in the electrolyte satisfies: 500ppm≤w2≤50000ppm; alternatively, 2000ppm≤w2≤20000ppm.

[0018] The content of metal ions in the electrolyte affects both the suppression of lithium dendrites and the impedance of the electrolyte. In the embodiments of this application, by controlling the content of metal ions in the electrolyte within a suitable range, it is helpful to improve the impedance of the lithium-ion battery while suppressing lithium dendrites.

[0019] In one possible implementation, the electrolyte comprises an inorganic salt, which includes the metal ions and anions; the anions include at least one of acetate, nitrate, hexafluorophosphate, perchlorate, and bis(trifluoromethanesulfonyl)imide anions.

[0020] In one possible implementation, the lithium-loving metal is obtained through a chemical reaction.

[0021] In one possible implementation, the chemical reaction includes atomic layer deposition, liquid phase deposition, and solid phase deposition.

[0022] In one possible implementation, the lithium-loving metal is obtained through an electrochemical reaction.

[0023] In a second aspect, a lithium-ion battery is provided, the lithium-ion battery comprising: a negative electrode sheet, the negative electrode active material layer of the negative electrode sheet comprising a lithium-metal alloy; and an electrolyte comprising metal ions, the reduction potential of the metal ions being higher than the reduction potential of the lithium ions.

[0024] In one possible implementation, the negative electrode active material layer comprises a lithium-loving metal, and the lithium-metal alloy comprises an alloy formed of lithium and the lithium-loving metal.

[0025] In one possible implementation, the lithium-metal alloy further includes an alloy formed from lithium and a metal obtained by reducing the metal ions.

[0026] In one possible implementation, the lithium-metal alloy is located on the surface of the negative electrode active material layer near the electrolyte.

[0027] In one possible implementation, the content w3 of the lithium-loving metal in the negative electrode sheet satisfies: 100ppm≤w3≤3000ppm.

[0028] In one possible implementation, the metal in the lithium-metal alloy includes at least one of Mg, Sn, Ag, Al, In, Zn, Ca, Sr, Ba, Sc, Y, Rh, Ir, Pd, Pt, Au, Cd, Ga, Ge, Pb, Sb, and Bi.

[0029] In one possible implementation, the metal ions include Mg. 2+ Sn 4+ Ag + Al 3+ In 3+ Zn 2+ Ca 2+ 、Sr 2+ Ba 2+ ,Sc + Y 3+ ,Rh 3+ Ir 3+ Pd 3+ Pt 3+ Au 2+ Cd 2+ Ga 3+ 、Ge 4+ Pb 4+ Sb 3+ Bi 3+ At least one of them.

[0030] In one possible implementation, the content w4 of the metal ions in the electrolyte satisfies: 100ppm≤w4≤48000ppm; alternatively, 300ppm≤w4≤19000ppm.

[0031] Thirdly, a method for preparing a lithium-ion battery is provided, the method comprising: preparing a lithium-philic metal in the negative electrode active material layer of a negative electrode sheet; adding metal ions to an electrolyte, wherein the reduction potential of the metal ions is higher than that of lithium ions; and assembling the negative electrode sheet and the electrolyte into the lithium-ion battery.

[0032] In one possible implementation, the preparation of the lithium-loving metal in the negative electrode active material layer of the negative electrode sheet includes: preparing the lithium-loving metal on the surface of the negative electrode active material layer near the electrolyte.

[0033] In one possible implementation, the preparation of the lithium-loving metal in the negative electrode active material layer of the negative electrode sheet includes: preparing the lithium-loving metal through a chemical reaction.

[0034] In one possible implementation, the chemical reaction includes atomic layer deposition, liquid phase deposition, and solid phase deposition.

[0035] In one possible implementation, the preparation of the lithium-loving metal in the negative electrode active material layer of the negative electrode sheet includes: preparing the lithium-loving metal by an electrochemical reaction.

[0036] In one possible implementation, the electrochemical reaction includes reducing the metal ions at their reduction potential to obtain the lithium-loving metal.

[0037] In one possible implementation, the SEI film of the negative electrode includes at least one of the lithium-philic metal fluoride and carbonate.

[0038] In one possible implementation, adding metal ions to the electrolyte includes adding an inorganic salt to the electrolyte, the inorganic salt comprising the metal ions and anions, the anions comprising at least one of acetate, nitrate, hexafluorophosphate, perchlorate, and bis(trifluoromethanesulfonyl)imide anions.

[0039] In one possible implementation, the lithium-loving metal includes at least one of Mg, Sn, Ag, Al, In, Zn, Ca, Sr, Ba, Sc, Y, Rh, Ir, Pd, Pt, Au, Cd, Ga, Ge, Pb, Sb, and Bi.

[0040] In one possible implementation, the metal ions include Mg. 2+ Sn 4+ Ag + Al 3+ In 3+ Zn 2+ Ca 2+ 、Sr 2+ Ba 2+ ,Sc + Y 3+ ,Rh 3+ Ir 3+ Pd 3+ Pt 3+ Au 2+ Cd 2+ Ga 3+ 、Ge 4+ Pb 4+ Sb 3+ Bi 3+ At least one of them.

[0041] Fourthly, an electrical device is provided, the electrical device comprising at least one of a lithium-ion battery in any possible implementation of the first aspect, a lithium-ion battery in any possible implementation of the second aspect, and a lithium-ion battery prepared by a method in any possible implementation of the third aspect. Attached Figure Description

[0042] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0043] Figure 1 This is a schematic flowchart of a method for preparing a lithium-ion battery.

[0044] Figure 2 This is a schematic diagram of a single battery cell.

[0045] Figure 3 This is a schematic diagram of a battery module.

[0046] Figure 4 This is a schematic diagram of a type of battery.

[0047] Figure 5 This is another schematic diagram of a battery. Detailed Implementation

[0048] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the lithium-ion battery, its preparation method, and the power-using device thereof. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0049] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0050] In the description of this application, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," etc., indicating orientation or positional relationships are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0051] Unless otherwise specified, in this application, the phrase "A and / or B" means "A, B, or both A and B". More specifically, the condition "A and / or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0052] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0053] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0054] Unless otherwise specified, the following terms have the following meanings. Any undefined terms have their technically accepted meanings.

[0055] If mentioned, "lithophile metals" refers to elemental metals that can form lithium-metal alloys with lithium, such as magnesium, zinc, and aluminum.

[0056] If mentioned, "lithium dendrites" refers to the dendritic metallic lithium formed when lithium ions are reduced during the cycling process of a lithium-ion battery.

[0057] If mentioned, "SEI film" refers to the solid electrolyte interface (SEI) film. The SEI film is a passivation film formed on the surface of the negative electrode during the charging process of a lithium-ion battery, consisting of lithium ions and some components of the electrolyte.

[0058] If mentioned, "particles" refers to nanoscale particles formed by the aggregation of multiple atoms or molecules.

[0059] The embodiments of this application will be described next.

[0060] In recent years, rechargeable batteries have seen significant development due to their high energy density and long lifespan, finding widespread application in power tools, electronic products, electric vehicles, aerospace, and other fields. Typically, a rechargeable battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During charging and discharging, active ions repeatedly insert and extract between the positive and negative electrodes. The electrolyte acts as a conductor of these active ions between the electrodes. The separator, positioned between the positive and negative electrodes, prevents short circuits while allowing active ions to pass through, ensuring the normal electrochemical reaction of the rechargeable battery.

[0061] Taking lithium-ion batteries as an example, lithium-ion batteries are a typical type of rechargeable battery. Because they rely on the chemical reaction of lithium ions intercalating and deintercalating between the positive and negative electrodes for charging and discharging, lithium-ion batteries are also known as rocking chair batteries. During the charging process of a lithium-ion battery, lithium ions are extracted from the positive electrode active material, move to the negative electrode through the conduction of the electrolyte, and intercalate into the negative electrode active material; while during the discharging process, lithium ions are extracted from the negative electrode active material, move to the positive electrode through the conduction of the electrolyte, and intercalate into the positive electrode active material.

[0062] It should be understood that the “lithium intercalation” or “intercalation” process described in this application refers to the process in which lithium ions are intercalated into the positive electrode active material or the negative electrode active material due to an electrochemical reaction, while the “de-lithium extraction”, “de-lithium extraction”, or “de-intercalation” process described in this application refers to the process in which lithium ions are extracted from the positive electrode active material or the negative electrode active material due to an electrochemical reaction.

[0063] During the charging and discharging process of a lithium-ion battery, factors such as changes in the battery's internal resistance, the balance between the rates of electrochemical reactions at the positive and negative electrodes and the speed of electron movement, and the diffusion rate of lithium ions participating in the electrochemical reactions all contribute to battery polarization. This causes lithium ions to deposit from the surface of the negative electrode active material layer, a process known as lithium plating. Further lithium ion deposition can lead to the formation and growth of lithium dendrites. The formation and growth of lithium dendrites continuously consume lithium ions, resulting in a decrease in battery capacity and cycle life. In severe cases, lithium dendrites may even puncture the separator, causing a short circuit between the positive and negative electrodes and triggering battery safety issues.

[0064] In view of this, embodiments of this application provide a lithium-ion battery and its preparation method and electrical device, wherein the lithium-ion battery has a negative electrode sheet including a lithium-philic metal and an electrolyte including metal ions. Both the lithium-philic metal and the metal ions can improve lithium deposition during the cycling process of the lithium-ion battery, thereby suppressing the formation of lithium dendrites and achieving suppression of lithium dendrites during the long-cycle process of the lithium-ion battery.

[0065] Typically, a lithium-ion battery includes a positive electrode, a negative electrode, an electrolyte, and a separator. The following section describes the lithium-ion battery provided in this application, as well as its various components.

[0066] First, a lithium-ion battery is provided, comprising a negative electrode and an electrolyte. The negative electrode active material layer comprises a lithium-philic metal; the electrolyte comprises metal ions, the reduction potential of which is higher than that of lithium ions.

[0067] Specifically, during the cycling process of a lithium-ion battery, when lithium plating occurs on the surface of the negative electrode active material layer, the lithiophilic metal in the negative electrode active material layer can react with the deposited lithium to form a lithium-metal alloy, initially suppressing lithium plating. However, during high-current or long-term cycling of the lithium-ion battery, the suppressive effect of the lithiophilic metal in the negative electrode active material layer is limited, and lithium dendrites may continue to grow and pierce the SEI film. Since the reduction potential of metal ions in the electrolyte is higher than that of lithium ions, the metal ions can be reduced to elemental metals by the deposited lithium, consuming the deposited lithium. Thus, continuous suppression of lithium dendrites is achieved during the long-term cycling process of the lithium-ion battery.

[0068] It should be understood that the elements of a lithium-loving metal and a metal ion can be the same or different.

[0069] This embodiment introduces a lithium-loving metal into the negative electrode active material layer of a lithium-ion battery, and simultaneously introduces metal ions into the electrolyte, which can effectively suppress the formation and / or growth of lithium dendrites, thereby improving the battery's safety performance and lifespan during long-cycle operation.

[0070] In one embodiment, the lithium-loving metal is located on the surface of the negative electrode active material layer near the electrolyte.

[0071] Specifically, lithium plating typically occurs on the surface of the negative electrode active material layer. In this embodiment, by introducing a lithiophilic metal onto the surface of the negative electrode active material layer near the electrolyte, the lithiophilic metal can react with the deposited lithium in a timely manner to form a lithium-metal alloy, thereby helping to improve the inhibitory effect of the lithiophilic metal on lithium plating.

[0072] For example, in the process of preparing a negative electrode active material layer including a lithium-philic metal, the content of lithium-philic metal on the surface of the negative electrode active material layer can be controlled to be higher than the content of lithium-philic metal near the current collector portion of the negative electrode active material layer.

[0073] In one embodiment, the lithium-loving metal includes at least one selected from Mg, Sn, Ag, Al, In, Zn, Ca, Sr, Ba, Sc, Y, Rh, Ir, Pd, Pt, Au, Cd, Ga, Ge, Pb, Sb, and Bi.

[0074] In one embodiment, the content w1 of the lithium-loving metal in the negative electrode sheet satisfies: 100ppm≤w1≤1000ppm.

[0075] Specifically, w1 can be 100ppm, 200ppm, 300ppm, 400ppm, 500ppm, 600ppm, 700ppm, 800ppm, 900ppm, 1000ppm, or a value range within the range obtained by any combination of the above two values.

[0076] On the one hand, if the content of the lithiophilic metal is too low, its inhibitory effect on lithium plating is limited, potentially leading to localized lithium plating in the negative electrode active material layer. On the other hand, if the content of the lithiophilic metal is too high, excessive coverage of the negative electrode active material layer results in a greater amount of alloy formation, increasing the impedance of the lithium-ion battery. Furthermore, the lithiophilic metal cannot contribute to the capacity of the lithium-ion battery, hindering the improvement of its energy density. In one possible implementation, the lithiophilic metal is prepared through an electrochemical reaction; specifically, it can be prepared by electrochemically reducing metal ions in the electrolyte. During the electrochemical reduction process, for example, the content of the lithiophilic metal in the negative electrode active material layer can be controlled by adjusting the concentration of metal ions in the electrolyte.

[0077] Therefore, by controlling the content w1 of the lithium-ion metal in the negative electrode sheet within a suitable range, this embodiment can effectively suppress lithium plating while reducing the influence of the lithium-ion metal on the impedance of the lithium-ion battery.

[0078] In one embodiment, the lithium-loving metal comprises single atoms and / or particles, the particle size d satisfying: 0 nm < d ≤ 3 nm.

[0079] Specifically, d can be 0.1nm, 0.2nm, 0.3nm, 0.4nm, 0.5nm, 0.6nm, 0.7nm, 0.8nm, 0.9nm, 1nm, 1.1nm, 1.2nm, 1.3nm, 1.4nm, 1.5nm, 1.6nm, 1.7nm, 1.8nm, 1.9nm, 2.0nm, 2.1nm, 2.2nm, 2.3nm, 2.4nm, 2.5nm, 2.6nm, 2.7nm, 2.8nm, 2.9nm, 3.0nm, or a value within the range obtained by any combination of the above two values.

[0080] Because lithopeptide metals are conductive, excessively large sizes of these metals can reduce the insulation of the SEI film on the surface of the negative electrode active material layer, leading to increased self-discharge of the lithium-ion battery and affecting its capacity and lifespan. In one possible implementation, the lithopeptide metal is prepared via an electrochemical reaction. During the electrochemical reduction process, the particle size of the lithopeptide metal can, exemplarily, be controlled by adjusting the time of the electrochemical reaction.

[0081] In this embodiment, the size of the lithium-ion metal is controlled within a small range, which can reduce the impact of introducing the lithium-ion metal into the negative electrode active material layer on the insulation of the SEI film formed on the surface of the negative electrode active material layer, thereby helping to reduce the self-discharge of the lithium-ion battery.

[0082] Lithophile metals, including single atoms, can be understood as having the morphology of a single metal atom. Lithophile metals, including particles, can be understood as having the morphology of an aggregation of multiple metal atoms.

[0083] In one embodiment, the SEI film of the negative electrode comprises at least one of a lithium-philic metal fluoride and a carbonate.

[0084] In one embodiment, the metal ion includes Mg. 2+ Sn 4+ Ag + Al 3+ In 3+ Zn 2+ Ca 2+ 、Sr 2+ Ba 2+ ,Sc + Y 3+ ,Rh 3+ Ir 3+ Pd 3+ Pt 3+ Au 2+ Cd 2+ Ga 3+ 、Ge 4+ Pb 4+ Sb 3+ Bi 3+ At least one of them.

[0085] Specifically, during the long-cycle process of lithium-ion batteries, when a large amount of the lithium-loving metal in the negative electrode is consumed and lithium plating can no longer be suppressed, the aforementioned metal ions can be reduced by lithium to form elemental metals. These elemental metals are lithium-loving and can continue to form lithium-metal alloys with lithium. The lithium-metal alloys can further induce uniform lithium deposition on the negative electrode, regulate the morphology of the negative electrode surface, and thus suppress the growth of lithium dendrites. This helps to improve the cycle performance and lifespan of lithium-ion batteries during long-cycle processes.

[0086] In another embodiment, after the metal ions are reduced to elemental metals by lithium, the elemental metals may not be lithium-loving; in other words, the elemental metals may not form lithium-metal alloys with lithium.

[0087] In one embodiment, the content of metal ions w2 in the electrolyte satisfies: 500ppm≤w2≤50000ppm; optionally, 2000ppm≤w2≤20000ppm.

[0088] Specifically, w2 can be 500ppm, 1000ppm, 1500ppm, 2000ppm, 2500ppm, 3000ppm, 3500ppm, 4000ppm, 4500ppm, 5000ppm, 5500ppm, 6000ppm, 6500ppm, 7000ppm, 7500ppm, 8000ppm, 8500ppm, 9000ppm, 9500ppm, 10000ppm, 15000ppm, 20000ppm, 25000ppm, 30000ppm, 35000ppm, 40000ppm, 45000ppm, 50000ppm, or a value range within the range obtained by any combination of the above two values.

[0089] On the one hand, if the metal ion content in the electrolyte is too low, its inhibitory effect on lithium plating is limited; on the other hand, if the metal ion content in the electrolyte is too high, it will lead to excessive viscosity of the electrolyte and increase the impedance of the lithium-ion battery.

[0090] In this embodiment, by controlling the content of metal ions in the electrolyte within a suitable range, it is helpful to suppress lithium dendrites while reducing the impact of metal ions on the impedance of lithium-ion batteries.

[0091] In one embodiment, the electrolyte comprises an inorganic salt, which includes the metal ions and anions; the anions include at least one of acetate, nitrate, hexafluorophosphate, perchlorate, and bis(trifluoromethanesulfonyl)imide anions.

[0092] In one embodiment, the lithium-loving metal is obtained through a chemical reaction.

[0093] In one embodiment, the chemical reaction includes atomic layer deposition (ALD), liquid phase deposition (LPD), and solid precipitation (SP).

[0094] In one embodiment, the lithium-loving metal is obtained via an electrochemical reaction.

[0095] The above embodiments introduced a lithium-ion battery capable of long-term suppression of lithium dendrites. Next, the lithium-ion battery after cycling will be described.

[0096] Embodiments of this application also provide a cycled lithium-ion battery, including a negative electrode and an electrolyte. The negative electrode active material layer comprises a lithium-metal alloy, and the electrolyte comprises metal ions, wherein the reduction potential of the metal ions is higher than that of the lithium ions.

[0097] It should be understood that, in the embodiments of this application, the cycled lithium-ion battery can be considered as a lithium-ion battery that has undergone lithium plating, i.e., a lithium-ion battery after lithium plating. As mentioned in the foregoing embodiments, the negative electrode of the lithium-ion battery includes a lithium-philic metal, and the electrolyte includes metal ions. Therefore, lithium plating occurs on the surface of the negative electrode active material layer of the cycled lithium-ion battery. The deposited lithium is consumed by the lithium-philic metal and / or metal ions, resulting in the negative electrode active material layer of the cycled lithium-ion battery comprising a lithium-metal alloy.

[0098] In one embodiment, the negative electrode active material layer comprises a lithium-loving metal, and the lithium-metal alloy comprises an alloy formed of lithium and a lithium-loving metal.

[0099] Specifically, when lithium deposition first begins on the surface of the negative electrode active material layer, the deposited lithium can react with the lithiophilic metal in the negative electrode active material layer to form a lithium-metal alloy. Therefore, the negative electrode active material layer of the cycled lithium-ion battery comprises a lithium-metal alloy formed by the lithiophilic metal and the deposited lithium.

[0100] In one embodiment, the lithium-metal alloy further includes an alloy formed from lithium and a metal obtained by the reduction of metal ions.

[0101] For example, during the long-term cycling of a lithium-ion battery, the content of lithium-philic metal in the negative electrode active material layer is limited. When the lithium-philic metal in the negative electrode active material layer can no longer improve lithium plating or inhibit lithium dendrite growth, lithium dendrites may continue to grow. When lithium dendrites pierce the SEI film on the surface of the negative electrode active material layer, free metal ions in the electrolyte can diffuse to the lithium dendrites and be reduced to elemental metals by lithium, subsequently reacting with lithium to form a lithium-metal alloy. Therefore, the negative electrode active material layer of a cycled lithium-ion battery can also include a lithium-metal alloy formed by the metal obtained from the reduction of metal ions and lithium. In other words, elemental metals obtained from the reduction of metal ions in the electrolyte can also participate in the formation of lithium-metal alloys.

[0102] It should be understood that, when the lithiophilic metal and the metal ion have the same element, the lithium-metal alloy in the post-cycle negative electrode active material layer can be a single-component alloy. For example, the lithiophilic metal is zinc (Zn), and the metal ion is zinc ion (Zn). 2+ If the lithium-metal alloy is a lithium-zinc alloy, then the composition of the lithium-metal alloy is a lithium-zinc alloy. When the lithiophilic metal and the metal ion are different elements, the lithium-metal alloy in the post-cycle negative electrode active material layer can be a multi-component alloy. For example, the lithiophilic metal is zinc (Zn), and the metal ion is magnesium ion (Mg). 2+ Therefore, the composition of lithium-metal alloys can include both lithium-zinc alloys and lithium-magnesium alloys.

[0103] In one embodiment, the lithium-metal alloy is located on the surface of the negative electrode active material layer near the electrolyte.

[0104] Specifically, in the case where the lithium-loving metal is located on the surface of the negative electrode active material layer, in the cycled lithium-ion battery, the lithium-metal alloy is also located on the surface of the negative electrode active material layer near the electrolyte.

[0105] In one embodiment, the content w3 of the lithium-loving metal in the negative electrode sheet satisfies: 100ppm≤w3≤3000ppm.

[0106] Specifically, w3 can be 100ppm, 200ppm, 300ppm, 400ppm, 500ppm, 600ppm, 700ppm, 800ppm, 900ppm, 1000ppm, 1200ppm, 1400ppm, 1600ppm, 1800ppm, 2000ppm, 2200ppm, 2400ppm, 2600ppm, 2800ppm, 3000ppm, or a value range within the range obtained by any combination of the above two values.

[0107] In one embodiment, the metal in the lithium-metal alloy includes at least one selected from Mg, Sn, Ag, Al, In, Zn, Ca, Sr, Ba, Sc, Y, Rh, Ir, Pd, Pt, Au, Cd, Ga, Ge, Pb, Sb, and Bi.

[0108] In one embodiment, the metal ion includes Mg. 2+ Sn 4+ Ag + Al 3+ In 3+ Zn 2+ Ca 2+ 、Sr 2+ Ba 2+ ,Sc + Y 3+ ,Rh 3+ Ir 3+ Pd 3+ Pt 3+ Au 2+ Cd 2+ Ga 3+ 、Ge 4+ Pb 4+ Sb 3+ Bi 3+ At least one of them.

[0109] In one embodiment, the content w4 of the metal ions in the electrolyte satisfies: 100ppm≤w4≤48000ppm; optionally, 300ppm≤w4≤19000ppm.

[0110] As the number of cycles in a lithium-ion battery increases, the content of metal ions in the electrolyte gradually decreases. For example, when lithium ions first begin to deposit lithium, the content of metal ions in the electrolyte, w4, satisfies 400ppm ≤ w4 ≤ 48000ppm, optionally 1800ppm ≤ w4 ≤ 19000ppm. As the metal ions are gradually consumed by lithium dendrites, the content of metal ions in the electrolyte, w4, satisfies: 100ppm ≤ w4 ≤ 42000ppm, optionally 300ppm ≤ w4 ≤ 14000ppm.

[0111] Specifically, W4 can be 100ppm, 200ppm, 300ppm, 400ppm, 500ppm, 600ppm, 700ppm, 800ppm, 900ppm, 1000ppm, 2000ppm, 3000ppm, 4000ppm, 5000ppm, 6000ppm, 7000ppm, 8000ppm, 9000ppm, 10000ppm, 11000ppm, 12000ppm, 13000ppm, 14000ppm, or 15000ppm. 16000ppm, 17000ppm, 18000ppm, 19000ppm, 20000ppm, 22000ppm, 24000ppm, 26000ppm, 28000ppm, 30000ppm, 32000ppm, 34000ppm, 36000ppm, 38000ppm, 40000ppm, 42000ppm, 44000ppm, 46000ppm, 48000ppm, or a value range within the range obtained by any combination of the above two values.

[0112] Next, we will provide a detailed introduction to the positive electrode, negative electrode, separator, and electrolyte in lithium-ion batteries.

[0113] [Negative electrode plate]

[0114] A negative electrode typically includes a negative current collector and a negative active material layer disposed on at least one surface of the negative current collector. The negative active material layer includes a negative active material and a lithium-loving metal.

[0115] As an example, the negative electrode current collector has two surfaces opposite each other in its thickness direction, and the negative electrode active material layer is disposed on either or both of these opposing surfaces. The negative electrode active material layer disposed on the surface of the negative electrode current collector also has two opposing surfaces in its thickness direction, with one surface in contact with the negative electrode current collector and the other surface away from it along the thickness direction. The "surface of the negative electrode active material layer near the electrolyte" mentioned in the embodiments of this application refers to the surface of the negative electrode active material layer away from the negative electrode current collector.

[0116] In one embodiment, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymeric material substrate and a metal layer formed on at least one surface of the polymeric material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymeric material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0117] In one embodiment, the negative electrode active material may be a negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0118] In one embodiment, the lithiophilic metal may be a metal known in the art capable of forming alloys with lithium. As an example, the lithiophilic metal may be selected from at least one of the following metals: Mg, Sn, Ag, Al, In, Zn, Ca, Sr, Ba, Sc, Y, Rh, Ir, Pd, Pt, Au, Cd, Ga, Ge, Pb, Sb, and Bi.

[0119] In one embodiment, the content w1 of the lithium-loving metal in the negative electrode active material layer satisfies: 100ppm≤w1≤1000ppm.

[0120] In one embodiment, the lithium-loving metal comprises single atoms and / or particles, the size d of which satisfies: 0 nm < d ≤ 3 nm.

[0121] In one embodiment, the negative electrode active material layer further includes a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0122] In one embodiment, the negative electrode active material layer further includes a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0123] In one embodiment, the negative electrode active material layer also includes other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0124] In one embodiment, the negative electrode sheet can be prepared by forming a negative electrode slurry using the components described above. For example, the negative electrode active material, conductive agent, binder, and any other components are dispersed in a solvent (e.g., N-methylpyrrolidone) to form the negative electrode slurry. The negative electrode slurry is then coated onto a negative electrode current collector, and after processes such as drying and rolling, the negative electrode sheet is obtained.

[0125] [Positive electrode plate]

[0126] The positive electrode includes a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector.

[0127] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0128] In one embodiment, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0129] In one embodiment, the positive electrode active material may be a known positive electrode active material for batteries. As an example, the positive electrode active material may include at least one of the following materials: lithium phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Examples of lithium-containing phosphates with an olivine structure include, but are not limited to, lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. During the charging and discharging process, Li undergoes insertion / extraction and consumption, resulting in different molar contents of Li in the positive electrode active material when the battery is discharged to different states. In the examples of positive electrode active materials in this application, the molar content of Li refers to the initial state of the material, i.e., the state before feeding. After charge-discharge cycles, the molar content of Li changes when the positive electrode active material is applied to the battery system. In the examples of positive electrode active materials in this application, the molar content of O is only an ideal value; lattice oxygen release causes changes in the molar content of O, and the actual molar content of O will fluctuate.

[0130] In one embodiment, the positive electrode active material layer further includes a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0131] In one embodiment, the positive electrode active material layer further includes a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0132] In one embodiment, the positive electrode sheet can be prepared by forming a positive electrode slurry from the components described above. For example, the positive electrode active material, conductive agent, binder, and any other components are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry. The positive electrode slurry is then coated onto a positive electrode current collector, and after processes such as drying and rolling, the positive electrode sheet is obtained.

[0133] Electrolyte

[0134] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not specify any particular type of electrolyte; it can be selected according to requirements. Electrolytes include electrolyte salts, solvents, and metal ions.

[0135] In one embodiment, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0136] In one embodiment, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0137] In one embodiment, the metal ions are provided by an inorganic salt. In other words, the electrolyte comprises an inorganic salt, which includes both the metal ions and anions. The metal ions include Mg. 2+ Sn 4+ Ag + Al 3+ In 3+ Zn 2+ Ca2+ 、Sr 2+ Ba 2+ ,Sc + Y 3+ ,Rh 3+ Ir 3+ Pd 3+ Pt 3+ Au 2+ Cd 2+ Ga 3+ 、Ge 4+ Pb 4+ Sb 3+ Bi 3+ At least one of the following anions. The anions include at least one of acetate, nitrate, hexafluorophosphate, perchlorate, and bis(trifluoromethanesulfonyl)imide anions.

[0138] In one embodiment, the electrolyte may also include additives, which may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0139] [Isolation Component]

[0140] In one embodiment, the battery also includes a separator. This application does not impose any particular limitation on the type of separator; for example, any known porous membrane with good chemical and mechanical stability can be selected.

[0141] In one embodiment, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0142] [Preparation Method]

[0143] Next, the method for preparing the lithium-ion battery in the aforementioned embodiments will be described.

[0144] This application also provides a method for preparing a lithium-ion battery. Figure 1 This is a schematic flowchart of the preparation method.

[0145] like Figure 1 As shown, method 100 includes:

[0146] S101, a lithium-loving metal is prepared in the negative electrode active material layer of the negative electrode sheet.

[0147] S102 involves adding metal ions to the electrolyte. The reduction potential of metal ions is higher than that of lithium ions.

[0148] S103 assembles the negative electrode and electrolyte into a lithium-ion battery.

[0149] In other words, a lithium-ion battery is prepared by fabricating a lithium-ion metal in the negative electrode active material layer, adding metal ions to the electrolyte, and using the negative electrode sheet containing the lithium-ion metal and the electrolyte containing the metal ions. For example, after winding a negative electrode sheet containing the lithium-ion metal, a positive electrode sheet, and a separator to form an electrode assembly, it is placed in a housing, an electrolyte containing metal ions is injected, and then the housing is encapsulated to obtain a lithium-ion battery.

[0150] It should be understood that in the process of implementing method 100, a lithium-loving metal can be prepared in the negative electrode active material layer first, and then metal ions can be added to the electrolyte; or metal ions can be added to the electrolyte first, and then a lithium-loving metal can be prepared in the negative electrode active material layer; or metal ions can be added to the electrolyte while preparing the lithium-loving metal in the negative electrode active material layer.

[0151] Optionally, in S101, preparing a lithium-loving metal in the negative electrode active material layer includes: preparing a lithium-loving metal on the surface of the negative electrode active material layer near the electrolyte.

[0152] Optionally, in S101, preparing a lithium-loving metal in the negative electrode active material layer includes: preparing a lithium-loving metal through a chemical reaction.

[0153] Optionally, the chemical reaction includes atomic layer deposition, liquid phase deposition, and solid phase deposition.

[0154] For example, atomic layer deposition (ALD) can be used to deposit lithium-ion metals layer by layer as single-atom films onto the surface of the negative electrode active material layer. ALD is advantageous for preparing lithium-ion metals with small particle sizes. As another example, liquid phase deposition (LPD) can be used to place the negative electrode active material layer in a solution, and lithium-ion metals can be prepared at the contact points between the negative electrode active material layer and the solution through chemical reactions in the solution. Yet another example is solid phase deposition (SPD), where precursors can be incorporated into the negative electrode active material layer, and a reaction can be induced in the precursors at high temperatures to obtain lithium-ion metals. Optionally, after LPD or SPD, acid washing can be performed to prepare lithium-ion metals with small particle sizes.

[0155] Optionally, in S101, preparing a lithium-loving metal in the negative electrode active material layer includes: preparing a lithium-loving metal by an electrochemical reaction.

[0156] Optionally, the electrochemical reaction includes reducing the metal ions at their reduction potential to obtain a lithium-loving metal.

[0157] Specifically, inorganic salts, including metal ions and anions, can be directly added to the electrolyte. The voltage of the lithium-ion battery is then adjusted to the reduction potential of the metal ions, causing them to be reduced to lithium-loving metals on the surface of the negative electrode active material layer.

[0158] It should be understood that the metal ions used in the electrochemical reduction reaction are the metal ions corresponding to the lithiophilic metals, and may be the same as or different from the metal ions in the lithium-ion battery electrolyte of the aforementioned embodiments. In other words, in one embodiment, the lithiophilic metal can be directly obtained by reduction from the metal ions in the electrolyte.

[0159] Optionally, the SEI film of the negative electrode includes at least one of a lithium-philic metal fluoride or carbonate.

[0160] The formation of the SEI film typically occurs at the solid-liquid interface between the negative electrode active material layer and the electrolyte. Therefore, for lithium-ion batteries where the negative electrode active material layer includes a lithium-ion metal, the lithium-ion metal will also participate in the formation of the SEI film, resulting in the SEI film containing the lithium-ion metal. Furthermore, during the electrochemical preparation of the lithium-ion metal, inorganic salts are added to the electrolyte, leaving some residual inorganic salts in the electrolyte after preparation. These residual inorganic salts can participate in the formation of the SEI film, thus ensuring that the SEI film includes at least one of a lithium-ion metal fluoride or carbonate.

[0161] Optionally, in S102, adding metal ions to the electrolyte includes adding an inorganic salt to the electrolyte, the inorganic salt including metal ions and anions, the anions including at least one of acetate, nitrate, hexafluorophosphate, perchlorate, and bis(trifluoromethanesulfonyl)imide anions.

[0162] Optionally, the lithium-loving metal includes at least one of Mg, Sn, Ag, Al, In, Zn, Ca, Sr, Ba, Sc, Y, Rh, Ir, Pd, Pt, Au, Cd, Ga, Ge, Pb, Sb, and Bi.

[0163] Optionally, the metal ion includes Mg 2+ Sn 4+ Ag + Al 3+ In 3+ Zn 2+ Ca 2+ 、Sr 2+ Ba 2+ ,Sc + Y 3+ ,Rh 3+ Ir 3+ Pd 3+ Pt 3+Au 2+ Cd 2+ Ga 3+ 、Ge 4+ Pb 4+ Sb 3+ Bi 3+ At least one of them.

[0164] Based on a similar principle, the lithium-ion battery in the aforementioned embodiments can be prepared by method 100. It has a negative electrode sheet including a lithium-philic metal and an electrolyte including metal ions, and can achieve the corresponding technical effects, which will not be elaborated here.

[0165] In one embodiment, the negative electrode, the positive electrode, and the separator can be fabricated into an electrode assembly using a winding process or a stacking process.

[0166] In one embodiment, the battery cell may include an outer packaging. This outer packaging can be used to encapsulate the electrode assembly and electrolyte described above.

[0167] In one embodiment, the outer packaging of the battery cell can be a rigid shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the battery cell can also be a flexible package, such as a pouch. The material of the flexible package can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0168] This application does not impose any particular limitation on the shape of the battery cell; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 2 This is an example of a square-structured battery cell 200.

[0169] It should be understood that the battery cell 200 may include the lithium-ion battery in the foregoing embodiments.

[0170] Figure 3 This is a sample battery module 300. (See reference...) Figure 3 In the battery module 300, multiple battery cells 200 can be arranged sequentially along the length of the battery module 300. Of course, they can also be arranged in any other manner. Furthermore, the multiple battery cells 200 can be fixed in place using fasteners. The multiple battery cells 200 can be battery cells 200 with the same chemical system or battery cells 200 with different chemical systems.

[0171] Alternatively, in one embodiment, the battery module 300 may further include a housing with a receiving space in which a plurality of battery cells 200 are received.

[0172] Optionally, in one embodiment, the battery module 300 can also be assembled into a battery, and the number of battery modules 300 contained in the battery can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery.

[0173] Figure 4 and Figure 5 This is a battery 400 used as an example. (See reference...) Figure 3 and Figure 4 The battery 400 may include a battery box and multiple battery modules 300 disposed within the battery box. The battery box includes an upper box 401 and a lower box 402, with the upper box 401 covering the lower box 402 to form a closed space for accommodating the battery modules 300. The multiple battery modules 300 may be arranged in any manner within the battery box.

[0174] It should be understood that in some embodiments, the battery 400 described above is also referred to as a battery pack. The individual battery cells 200 can be first assembled into a battery module 300, and the battery 400 is composed of the battery module 300. Alternatively, the battery 400 can be directly assembled from the individual battery cells 200, omitting the intermediate form of the battery module 300.

[0175] In addition, this application also provides an electrical device, which includes at least one of the lithium-ion batteries in the foregoing embodiments or lithium-ion batteries prepared by method 100.

[0176] In another embodiment, the electrical device includes at least one of the battery cell 200, battery module 300, or battery 400 provided in this application. The battery cell 200, battery module 300, or battery 400 can be the power source of the electrical device or the energy storage unit of the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0177] As an electrical device, you can choose a single battery cell 200, a battery module 300, or a battery 400 according to your usage requirements.

[0178] This is an example of an electrical device. The device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements of the secondary battery for this device, a battery pack or battery module can be used.

[0179] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a rechargeable battery as their power source.

[0180] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0181] [Examples 1-16 and Comparative Examples 1-3]

[0182] Example 1

[0183] (1) Preparation of negative electrode sheet

[0184] The negative electrode active material graphite, conductive agent acetylene black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC) are dissolved in deionized water and mixed evenly to obtain a negative electrode slurry. The negative electrode slurry is then uniformly coated onto a negative electrode current collector copper foil. After cold pressing and slitting, the negative electrode sheet is obtained. The lithium-philic metal in the negative electrode active material layer is prepared through an electrochemical reaction, which will be described in detail in the lithium-ion battery manufacturing process.

[0185] (2) Preparation of positive electrode sheet

[0186] Lithium nickel cobalt manganese oxide (LCM), acetylene black (conductive agent), and polyvinylidene fluoride (PVDF) (binder) are dissolved in N-methylpyrrolidone (NMP) and mixed evenly to obtain a positive electrode slurry. The positive electrode slurry is then uniformly coated onto an aluminum foil current collector. Finally, it is cold-pressed and slit to obtain the positive electrode sheet.

[0187] (3) Preparation of electrolyte

[0188] Inorganic magnesium nitrate was added to a 1 mol / L LiPF6 electrolyte to make the mass fraction of magnesium nitrate in the electrolyte 0.8%. At this time, the content of magnesium ions in the electrolyte was 1300 ppm, and electrolyte 1 was obtained.

[0189] Inorganic magnesium nitrate was added to a 1 mol / L LiPF6 electrolyte to make the mass fraction of magnesium nitrate 1.2%. At this time, the content of magnesium ions in the electrolyte w2 was 2000 ppm, thus obtaining electrolyte 2.

[0190] The content of a certain substance in an electrolyte can be understood as the mass content of that substance in the electrolyte.

[0191] (4) Preparation of lithium-ion batteries

[0192] The positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes to isolate them. The stacked components are then wound into a housing, dried, injected with electrolyte 1, and encapsulated to obtain the battery.

[0193] The battery was tested at 0.6V (vs Li). + Under constant voltage conditions (electrolyte 1, magnesium ions in electrolyte 1 are reduced to lithium-philic metal (magnesium) on the surface of the negative electrode active material layer. The content w1 and size d of lithium-philic metal (magnesium) of the negative electrode are measured at this time. Then electrolyte 1 is removed, electrolyte 2 is added, and the battery is packaged to obtain a lithium-ion battery.

[0194] In Example 1, the content of lithium-ion metal in the negative electrode active material layer of the lithium-ion battery is w1 = 300 ppm, the size of the lithium-ion metal is d = 2 nm, and the content of metal ions in the electrolyte is w2 = 2000 ppm.

[0195] Example 2

[0196] Compared to Example 1, w1 = 100 ppm in Example 2.

[0197] Example 3

[0198] Compared to Example 1, w1 = 1000 ppm in Example 3.

[0199] Example 4

[0200] Compared to Example 1, w1 = 1200 ppm in Example 4.

[0201] Example 5

[0202] Compared to Example 1, d = 3nm in Example 6.

[0203] Example 6

[0204] Compared to Example 1, Example 6 prepared a lithiophilic metal via atomic layer deposition. The specific process was as follows: using bis(cyclopentadiene)magnesium as a precursor and ozone as a reactant, a cycle consisted of a 300-s precursor pulse, a 120-s nitrogen purging, a 40-s ozone pulse, and a 20-s nitrogen purging. After one cycle, metallic magnesium was deposited on the graphite surface. This yielded a lithiophilic metal with a d = 0.3 nm.

[0205] Example 7

[0206] Compared to Example 1, Example 7 prepared a lithiophilic metal via liquid phase deposition. The specific process was as follows: magnesium chloride and graphite were mixed in water and stirred until homogeneous. The water was then removed by rotary evaporation. The resulting sample was then reduced at 500°C for 2 hours in an atmosphere containing an argon-hydrogen mixture (95% Ar, 5% H2). The loaded sample was then acid-washed in 1 mol / L hydrochloric acid for 12 hours, followed by filtration until the filtrate was neutral. This yielded a lithiophilic metal with a d = 20 nm.

[0207] Example 8

[0208] Compared to Example 1, w2 = 500 ppm in Example 8.

[0209] Example 9

[0210] Compared to Example 1, w2 = 50000 ppm in Example 9.

[0211] Example 10

[0212] Compared to Example 1, w2 = 20000ppm in Example 10.

[0213] Example 11

[0214] Compared to Example 1, w2 = 400 ppm in Example 11.

[0215] Example 12

[0216] Compared to Example 1, in Example 12, the inorganic salt added to electrolyte 1 is magnesium hexafluorophosphate, and the mass fraction of magnesium hexafluorophosphate in electrolyte 1 is 1.7%. The inorganic salt added to electrolyte 2 is magnesium hexafluorophosphate, and the mass fraction of magnesium hexafluorophosphate in electrolyte 2 is 2.6%. Therefore, w2 = 2000 ppm in Example 12.

[0217] Example 13

[0218] Compared to Example 1, in Example 13, the inorganic salt added to electrolyte 1 is magnesium bis(trifluoromethanesulfonyl)imide, and the mass fraction of magnesium bis(trifluoromethanesulfonyl)imide in electrolyte 1 is 3.2%. The inorganic salt added to electrolyte 2 is magnesium bis(trifluoromethanesulfonyl)imide, and the mass fraction of magnesium bis(trifluoromethanesulfonyl)imide in electrolyte 2 is 4.9%. Therefore, w2 = 2000 ppm in Example 13.

[0219] Example 14

[0220] Compared to Example 1, the lithium-loving metal in Example 14 is tin. Specifically, in the preparation of the electrolyte, the inorganic salt added to electrolyte 1 and electrolyte 2 is tin nitrate, with mass fractions of 2.0% and 3.1%, respectively. In the preparation of the lithium-ion battery, at 2.0V (vs Li + Under constant voltage conditions (electrolyte 1, tin ions), the free tin ions in electrolyte 1 are reduced to lithium-philic metal (tin) on the surface of the negative electrode active material layer. Electrolyte 1 is then removed, electrolyte 2 is added, and the mixture is encapsulated to obtain a lithium-ion battery. In Example 14, w1 = 300 ppm, w2 = 2000 ppm, and d = 2 nm.

[0221] Example 15

[0222] Compared to Example 1, the lithium-philic metal in Example 15 is silver. Specifically, in the preparation of the electrolyte, the inorganic salt added to both electrolyte 1 and electrolyte 2 is silver nitrate, with mass fractions of 0.9% and 1.4%, respectively. In the preparation of the lithium-ion battery, at 2.0V (vs Li + Under constant voltage conditions (electrolyte 1, w1 = 300 ppm, w2 = 2000 ppm, d = 2 nm), the free silver ions in electrolyte 1 are reduced to lithium-philic metal (silver) on the surface of the negative electrode active material layer. Electrolyte 1 is then removed, electrolyte 2 is added, and the battery is encapsulated to obtain a lithium-ion battery. In Example 15, w1 = 300 ppm, w2 = 2000 ppm, d = 2 nm.

[0223] Example 16

[0224] Compared to Example 1, the metal ion in Example 16 is silver ion. Specifically, in preparing electrolyte 2, the inorganic salt added is silver nitrate with a mass fraction of 1.4%. In Example 16, w2 = 2000 ppm.

[0225] Comparative Example 1

[0226] Compared to Example 1, the negative electrode active material layer of the negative electrode in Comparative Example 1 does not contain a lithium-philic metal, and the electrolyte also does not contain metal ions. Specifically, in the process of preparing a lithium-ion battery, the positive electrode, separator, and negative electrode are stacked in sequence, such that the separator is positioned between the positive and negative electrodes and can isolate them; then the stacked components are wound and placed in a casing, dried, and injected with a 12.7% (w / w) LiPF6 electrolyte, and then packaged to obtain a lithium-ion battery.

[0227] Comparative Example 2

[0228] Compared to Example 1, in Comparative Example 2, the negative electrode active material layer of the negative electrode sheet includes a lithium-philic metal, but there are no metal ions in the electrolyte. Specifically, in the process of preparing the lithium-ion battery, after removing electrolyte 1, a LiPF6 electrolyte with a mass fraction of 12.7% is injected, and after encapsulation, a lithium-ion battery is obtained.

[0229] Comparative Example 3

[0230] Compared to Example 1, in Comparative Example 3, the negative electrode active material layer of the negative electrode does not contain a lithium-philic metal, but the electrolyte contains metal ions. Specifically, in the process of preparing a lithium-ion battery, the positive electrode, separator, and negative electrode are stacked in sequence, such that the separator is positioned between the positive and negative electrodes and can isolate them; then the stacked components are wound and placed in a casing, dried, injected with electrolyte 2, and encapsulated to obtain a lithium-ion battery.

[0231] The product parameters of Examples 1-16 and Comparative Examples 1-3 are detailed in Table 1.

[0232] Table 1: Product parameters of Examples 1-16 and Comparative Examples 1-3

[0233]

[0234]

[0235] In Table 1, "lithophile metal" refers to the lithiophile metal in the negative electrode active material layer; "preparation method" refers to the preparation method of the lithiophile metal; "w1" represents the content of the lithiophile metal in the negative electrode sheet; "d" represents the size of the lithiophile metal; "inorganic salt" represents the substance that provides metal ions in the electrolyte; "metal ion" represents the metal ions in the electrolyte; and "w2" represents the content of the lithiophile metal in the electrolyte.

[0236] The performance of the lithium-ion batteries in Examples 1-16 and Comparative Examples 1-3 was tested, and the product performance data are detailed in Table 2.

[0237] Table 2 Product performance data of Examples 1-16 and Comparative Examples 1-3

[0238]

[0239]

[0240] Comparative analysis of Examples 1-16 and Comparative Examples 1-3 shows that by introducing a lithium-loving metal into the negative electrode active material layer and introducing metal ions into the electrolyte, the growth of lithium dendrites can be continuously suppressed during the long cycle of the battery, effectively improving the cycle performance and service life of the lithium-ion battery.

[0241] Regarding the DCR of lithium-ion batteries, it can be seen that the DCR of the lithium-ion batteries in Examples 1-16 is only slightly larger than that in Comparative Examples 1-3, but the cycle performance of the lithium-ion batteries in the examples is significantly higher than that in the comparative examples. This indicates that introducing lithiophilic metals and metal ions into lithium-ion batteries has a certain impact on the DCR, but overall, it helps to significantly improve the cycle performance of lithium-ion batteries. According to the comparative analysis of Examples 1-4, the DCR of lithium-ion batteries increases with the increase of the lithiophilic metal content w1 in the negative electrode. In Example 4, the lithiophilic metal content w1 in the negative electrode is 1200 ppm, exceeding the range of 100 ppm-1000 ppm, resulting in a significant increase in the DCR of the lithium-ion battery. Therefore, it shows that by controlling w1 within a suitable range, it is possible to improve the cycle performance of lithium-ion batteries without significantly increasing their impedance.

[0242] Regarding the self-discharge of lithium-ion batteries, it can be seen that the self-discharge of lithium-ion batteries in Examples 1-16 is only slightly greater than that of lithium-ion batteries in Comparative Examples 1-3, but the cycle performance of lithium-ion batteries in the examples is significantly higher than that of the comparative examples. This indicates that introducing lithiophilic metals and metal ions into lithium-ion batteries has a certain influence on the self-discharge, but overall, it helps to significantly improve the cycle performance of lithium-ion batteries. According to the comparative analysis of Examples 1 and Examples 5-7, the lithiophilic metal in the negative electrode active material layer can be prepared by different methods such as electrochemical reduction, atomic layer deposition, and liquid phase deposition. Furthermore, in Examples 1 and 5-6, the size d of the lithiophilic metal is relatively small (0nm < d ≤ 3nm), resulting in a smaller self-discharge of the lithium-ion battery. However, in Example 7, the size d of the lithiophilic metal reaches 20nm, and the self-discharge of the lithium-ion battery is greater than that in Examples 5-6. If the self-discharge of the lithium-ion battery further increases, it will be detrimental to improving its cycle performance. Therefore, it shows that by controlling the size of the lithiophilic metal within a suitable range, it is possible to improve the cycle performance of lithium-ion batteries without significantly increasing their self-discharge.

[0243] Comparative analysis of Examples 1 and 8-11 shows that the metal ion content (w2) in the electrolyte of the lithium-ion battery in Example 11 is 400 ppm, which is outside the range of 500 ppm to 50,000 ppm. Due to the low metal ion content, the inhibition effect on lithium dendrites is limited, and the lithium-ion battery fails after 800 cycles. In contrast, the lithium-ion batteries in the other examples can cycle for 1500 cycles without failure. This demonstrates that by controlling the metal ion content within a suitable range, a sustained inhibition effect on lithium dendrites can be achieved, thereby improving the cycle performance of the lithium-ion battery. Examples 8-10 also show that as the metal ion content in the electrolyte increases, the impedance of the lithium-ion battery increases. This indicates that by controlling the metal ion content within a suitable range, the impedance of the lithium-ion battery can be kept from increasing significantly.

[0244] Examples 12-13 illustrate that lithium-loving metals can be provided by salts other than magnesium nitrate.

[0245] Examples 14-15 illustrate that the lithiophilic metal can also be tin or silver; the metal ion can also be tin ion or silver ion.

[0246] In Example 16, the lithiophilic metal is magnesium and the metal ion is silver ion, which shows that the elements of the lithiophilic metal and the metal ion can be the same or different.

[0247] [Examples 17-23 and Comparative Example 4]

[0248] Example 17

[0249] The lithium-ion battery in Example 17 is the lithium-ion battery from Example 1 after 1500 cycles. The lithium-ion battery was disassembled to test the magnesium metal content (w3) in the negative electrode and the magnesium ion content (w4) in the electrolyte. In Example 17, w3 = 800 ppm and w4 = 200 ppm.

[0250] Example 18

[0251] The lithium-ion battery in Example 18 is the lithium-ion battery from Example 2 after 10 cycles. In Example 18, w3 = 100 ppm and w4 = 2000 ppm.

[0252] Example 19

[0253] The lithium-ion battery in Example 19 is the lithium-ion battery from Example 2 after 1500 cycles. In Example 19, w3 = 600ppm and w4 = 900ppm.

[0254] Example 20

[0255] The lithium-ion battery in Example 20 is the lithium-ion battery from Example 4 after 1500 cycles. In Example 20, w3 = 3000ppm and w4 = 100ppm.

[0256] Example 21

[0257] The lithium-ion battery in Example 21 is the lithium-ion battery from Example 8 after 10 cycles. In Example 21, w3 = 300ppm and w4 = 500ppm.

[0258] Example 22

[0259] The lithium-ion battery in Example 22 is the lithium-ion battery from Example 8 after 1500 cycles. In Example 22, w3 = 400 ppm and w4 = 100 ppm.

[0260] Example 23

[0261] The lithium-ion battery in Example 23 is the lithium-ion battery from Example 9 after 1000 cycles. In Example 23, w3 = 800 ppm and w4 = 48000 ppm.

[0262] Comparative Example 4

[0263] Comparative Example 4 is the lithium-ion battery after Comparative Example 1 has undergone 100 cycles.

[0264] Comparative Example 5

[0265] Comparative Example 5 is the lithium-ion battery after Comparative Example 2 has undergone 500 cycles.

[0266] Comparative Example 6

[0267] Comparative Example 6 is the lithium-ion battery after Comparative Example 3 has undergone 600 cycles.

[0268] The product parameters and performance parameters of Examples 17-23 and Comparative Examples 4-6 are detailed in Table 3.

[0269] Table 3: Product parameters and performance parameters of Examples 17-23 and Comparative Examples 4-6

[0270] w1(ppm) w2 (ppm) w3(ppm) w4 (ppm) Number of cycles Failure cycles Example 17 300 2000 800 200 1500 ＞1500 Example 18 100 2000 100 2000 10 ＞1500 Example 19 100 2000 600 900 1500 ＞1500 Example 20 1200 2000 3000 100 1500 ＞1500 Example 21 300 500 300 500 10 ＞1500 Example 22 300 500 400 100 1500 ＞1500 Example 23 300 50000 800 48000 1000 ＞1500 Comparative Example 4 / / / / 100 100 Comparative Example 5 300 / 200 / 500 500 Comparative Example 6 / 2000 700 100 600 600

[0271] In Table 2, "w1" represents the content of lithium-ion metal in the negative electrode before cycling; "w2" represents the content of lithium-ion metal in the electrolyte before cycling; "w3" represents the content of lithium-ion metal in the negative electrode after cycling; and "w4" represents the content of metal ions in the electrolyte after cycling. "Number of Failure Cycles" indicates the number of battery cycles that failed.

[0272] As shown in Table 3, the lithium-ion battery content after cycling is related to its content before cycling. The metal ion content in the lithium-ion battery after cycling is also related to its content before cycling.

[0273] The comparative analysis of Example 17 and Comparative Examples 4-6 shows that introducing a lithium-loving metal into the negative electrode active material layer and introducing metal ions into the electrolyte can continuously suppress lithium dendrites during long-term cycling of lithium-ion batteries, effectively improving the cycle performance and service life of lithium-ion batteries.

[0274] Based on the comparative analysis of Examples 18-19 and 21-22, it can be reasonably inferred that during the long-cycle process of lithium-ion batteries, when lithium plating first begins (when the number of cycles is low), a lithium-metal alloy is formed first with the lithiophilic metal in the negative electrode active material layer. Since the lithium-metal alloy is still in the negative electrode active material layer, and at this time, no metal ions in the electrolyte are consumed. Therefore, in Examples 18 and 21, the lithiophilic metal content and the metal ion content are consistent before and after cycling. As the battery continues to cycle, lithium plating further occurs. After lithium dendrites grow and pierce the SEI film, they begin to consume metal ions in the electrolyte and further form a lithium-metal alloy. Thus, in Examples 19 and 22, the lithiophilic metal content in the cycled lithium-ion batteries is significantly increased, while the metal ion content in the electrolyte is significantly decreased.

[0275] The following is a brief description of the testing methods for the physicochemical and performance parameters involved in the embodiments of this application. It should be understood that the following testing methods are only examples, and other testing methods known in the art can also be used for testing.

[0276] 1. Methods for testing the reduction potential of metal ions

[0277] According to the Nernst equation, the reduction potential of metal ions relative to lithium at a concentration of 1 mol / L is calculated at different concentrations. The metal ions can be reduced by selecting a lithium reduction potential lower than this value.

[0278] 2. Content testing methods

[0279] Take a portion of the sample to be tested, such as the negative electrode or electrolyte; and directly measure the content of the target element in the sample by ICP (Inductively Coupled Plasma) test.

[0280] 3. Dimensional testing methods

[0281] Take a portion of the sample to be tested, such as the negative electrode sheet, and use TEM (Transmission Electron Microscope) or AC-TEM (Spherical Aberration Corrected Transmission Electron Microscope) to obtain a microscopic image of the sample, thereby obtaining the sample size.

[0282] 4. Test methods for self-discharge of lithium-ion batteries

[0283] The battery was charged to 3.75V (lithium nickel cobalt manganese oxide positive electrode) with a constant current of 0.33C, and then charged to 0.05C with a constant voltage of 3.75V. After the cell was left at room temperature for 12 hours, the voltage V0 of the battery was measured. After being left for another 48 hours, the voltage V1 was measured. The self-discharge is (V1-V0) / 48.

[0284] 5. Test methods for DCR of lithium-ion batteries

[0285] The prepared lithium-ion battery was first discharged at 25°C with a current of 0.33C to a voltage of 2.5V. After resting for 30 minutes, it was charged with a current of 0.33C to a voltage of 4.3V, and then charged at a constant voltage of 4.3V until the current was less than 0.05C. After resting for 30 minutes, it was discharged with a current of 0.33C to a voltage of 2.5V. At this point, the battery capacity C0 was obtained. The battery was then charged with a current of 0.33C to a voltage of 4.3V, and then charged at a constant voltage of 4.3V until the current was less than 0.05C. After resting for 30 minutes, it was discharged with a current of 0.33C to obtain 0.5C0 of capacity, bringing the SOC of the lithium-ion battery to 50%. The voltage of the battery at this point was recorded as V1. Finally, it was discharged with a current of 4C for 30 seconds. The voltage of the battery at this point was recorded as V2. The DCR (in mΩ) of the battery was obtained using the formula: (V1-V2) / (4C×1000).

[0286] 6. Test method for the number of cycles of lithium-ion battery failure

[0287] The lithium-ion battery was charged at a current of 2C to a voltage of 4.3V, then charged at a constant voltage of 4.3V until the current was less than 0.05C. After resting for 30 minutes, it was discharged at a current of 1C to a voltage of 2.5V. The above steps were repeated, and the number of cycles when the lithium-ion battery capacity decayed to 80% was recorded.

[0288] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A lithium-ion battery, characterized in that, The lithium-ion battery includes: A negative electrode sheet, wherein the negative electrode active material layer of the negative electrode sheet includes a lithium-philic metal; An electrolyte comprising metal ions, wherein the reduction potential of the metal ions is higher than that of lithium ions; The lithium-loving metal comprises single atoms and / or particles, wherein the particle size d satisfies: 0 < d ≤ 3 nm.

2. The lithium-ion battery according to claim 1, characterized in that, The lithium-loving metal is located on the surface of the negative electrode active material layer near the electrolyte.

3. The lithium-ion battery according to claim 1 or 2, characterized in that, The lithiophilic metal includes at least one of Mg, Sn, Ag, Al, In, Zn, Ca, Sr, Ba, Sc, Y, Rh, Ir, Pd, Pt, Au, Cd, Ga, Ge, Pb, Sb, and Bi.

4. The lithium-ion battery according to any one of claims 1-3, characterized in that, The content w1 of the lithium-loving metal in the negative electrode sheet satisfies: 100 ppm ≤ w1 ≤ 1000 ppm.

5. The lithium-ion battery according to any one of claims 1-4, characterized in that, The metal ions include Mg 2+ Sn 4+ Ag + Al 3+ In 3+ Zn 2+ Ca 2+ 、Sr 2+ Ba 2+ ,Sc + Y 3+ ,Rh 3+ Ir 3+ Pd 3+ Pt 3+ Au 2+ Cd 2+ Ga 3+ 、Ge 4+ Pb 4+ Sb 3+ Bi 3+ At least one of them.

6. The lithium-ion battery according to any one of claims 1-5, characterized in that, The content w2 of the metal ions in the electrolyte satisfies: 500 ppm ≤ w2 ≤ 50000 ppm.

7. The lithium-ion battery according to claim 6, characterized in that, 2000 ppm≤w2≤20000 ppm.

8. The lithium-ion battery according to any one of claims 1-7, characterized in that, The electrolyte comprises inorganic salts, which include the metal ions and anions; The anion includes at least one of acetate, nitrate, hexafluorophosphate, perchlorate, and bis(trifluoromethanesulfonyl)imide anion.

9. The lithium-ion battery according to any one of claims 1-8, characterized in that, The lithium-loving metal is obtained through a chemical reaction.

10. The lithium-ion battery according to claim 9, characterized in that, The chemical reactions include atomic layer deposition, liquid phase deposition, and solid phase deposition.

11. The lithium-ion battery according to any one of claims 1-8, characterized in that, The SEI film of the negative electrode includes at least one of the lithium-loving metal fluoride and carbonate.

12. The lithium-ion battery according to claim 11, characterized in that, The lithiophilic metal is obtained through an electrochemical reaction.

13. A lithium-ion battery, characterized in that, The lithium-ion battery includes: The negative electrode sheet, wherein the negative electrode active material layer of the negative electrode sheet includes a lithium-metal alloy and a lithium-philic metal; An electrolyte comprising metal ions, wherein the reduction potential of the metal ions is higher than that of lithium ions; The lithium-loving metal comprises single atoms and / or particles, wherein the particle size d satisfies: 0 < d ≤ 3 nm.

14. The lithium-ion battery according to claim 13, characterized in that, The lithium-metal alloy includes an alloy formed of lithium and the lithium-affinity metal.

15. The lithium-ion battery according to claim 13 or 14, characterized in that, The lithium-metal alloy also includes an alloy formed from the metal obtained by reducing lithium with the metal ions.

16. The lithium-ion battery according to any one of claims 13-15, characterized in that, The lithium-metal alloy is located on the surface of the negative electrode active material layer near the electrolyte.

17. The lithium-ion battery according to any one of claims 14-16, characterized in that, The content w3 of the lithium-metal alloy in the negative electrode sheet satisfies: 100 ppm ≤ w3 ≤ 3000 ppm.

18. The lithium-ion battery according to any one of claims 13-17, characterized in that, The metal in the lithium-metal alloy includes at least one of Mg, Sn, Ag, Al, In, Zn, Ca, Sr, Ba, Sc, Y, Rh, Ir, Pd, Pt, Au, Cd, Ga, Ge, Pb, Sb, and Bi.

19. The lithium-ion battery according to any one of claims 13-18, characterized in that, The metal ions include Mg 2+ Sn 4+ Ag + Al 3+ In 3+ Zn 2+ Ca 2+ 、Sr 2+ Ba 2+ ,Sc + Y 3+ ,Rh 3+ Ir 3+ Pd 3+ Pt 3+ Au 2+ Cd 2+ Ga 3+ 、Ge 4+ Pb 4+ Sb 3+ Bi 3+ At least one of them.

20. The lithium-ion battery according to any one of claims 13-19, characterized in that, The content w4 of the metal ions in the electrolyte satisfies: 100 ppm ≤ w4 ≤ 48000 ppm.

21. The lithium-ion battery according to claim 20, characterized in that, 300 ppm≤w4≤19000 ppm.

22. A method for preparing a lithium-ion battery, characterized in that, The method includes: Prepare a lithium-loving metal in the negative electrode active material layer of the negative electrode sheet; Metal ions are added to the electrolyte, wherein the reduction potential of the metal ions is higher than that of lithium ions; The negative electrode and the electrolyte are assembled into a lithium-ion battery. The lithium-loving metal comprises single atoms and / or particles, wherein the particle size d satisfies: 0 < d ≤ 3 nm.

23. The method according to claim 22, characterized in that, The preparation of a lithium-philic metal in the negative electrode active material layer of the negative electrode sheet includes: The lithium-loving metal is prepared on the surface of the negative electrode active material layer near the electrolyte.

24. The method according to claim 22 or 23, characterized in that, The preparation of a lithium-philic metal in the negative electrode active material layer of the negative electrode sheet includes: The lithium-loving metal is prepared by a chemical reaction.

25. The method according to claim 24, characterized in that, The chemical reactions include atomic layer deposition, liquid phase deposition, and solid phase deposition.

26. The method according to claim 22 or 23, characterized in that, The preparation of a lithium-philic metal in the negative electrode active material layer of the negative electrode sheet includes: The lithium-loving metal is prepared by an electrochemical reaction.

27. The method according to claim 26, characterized in that, The electrochemical reaction includes: The metal ions are reduced at their reduction potential to obtain the lithium-loving metal.

28. The method according to claim 27, characterized in that, The SEI film of the negative electrode includes at least one of the lithium-loving metal fluoride and carbonate.

29. The method according to any one of claims 22-28, characterized in that, The addition of metal ions to the electrolyte includes: An inorganic salt is added to the electrolyte, the inorganic salt including the metal ions and anions, the anions including at least one of acetate, nitrate, hexafluorophosphate, perchlorate, and bis(trifluoromethanesulfonyl)imide anions.

30. The method according to any one of claims 22-29, characterized in that, The lithiophilic metal includes at least one of Mg, Sn, Ag, Al, In, Zn, Ca, Sr, Ba, Sc, Y, Rh, Ir, Pd, Pt, Au, Cd, Ga, Ge, Pb, Sb, and Bi.

31. The method according to any one of claims 22-30, characterized in that, The metal ions include Mg 2+ Sn 4 + Ag + Al 3+ In 3+ Zn 2+ Ca 2+ 、Sr 2+ Ba 2+ ,Sc + Y 3+ ,Rh 3+ Ir 3+ Pd 3+ Pt 3+ Au 2+ Cd 2+ Ga 3+ 、Ge 4+ Pb 4+ Sb 3+ Bi 3+ At least one of them.

32. An electrical appliance, characterized in that, The electrical device includes at least one of the following: a lithium-ion battery as described in any one of claims 1-12, a lithium-ion battery as described in any one of claims 13-21, and a lithium-ion battery prepared by the method as described in any one of claims 22-31.

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