Battery, lithium replenishment method for battery, and electric device

Abstract

The present application belongs to the technical field of batteries, and particularly relates to a battery, a lithium replenishment method for a battery, and an electric device. The battery comprises a positive electrode, a negative electrode and a lithium-replenishing electrode, wherein the lithium-replenishing electrode, the positive electrode and the negative electrode are isolated from each other; the lithium-replenishing electrode comprises a lithium-replenishing matrix and a protective layer coating the lithium-replenishing matrix; and the lithium-replenishing matrix comprises a lithium-replenishing agent, and the protective layer has ionic conductivity. The technical solution of the present application can effectively recover the capacity loss of the battery caused by the loss of active lithium, and prolong the cycle life of the battery.

Description

Battery, battery lithium replenishment method, and power-using device

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on July 14, 2023, with application number CN202310863735.6 and invention name “Battery, Battery Lithium Replenishing Method, and Electrical Device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application belongs to the field of battery technology, and in particular relates to batteries, battery lithium replenishment methods, and electrical devices. Background Art

[0003] With the continuous deepening of battery research and the continuous increase in market demand, higher requirements are being placed on various battery performance characteristics, including cycle life, which has a significant impact on the user experience. A battery's cycle life is the number of charge and discharge cycles a battery can undergo while maintaining a certain capacity. In actual research and use, after a certain number of cycles, the battery's capacity rapidly decays, shortening its cycle life.

[0004] Summary of the Invention

[0005] In view of the above problems, the present application provides a battery, a battery lithium replenishment method, and an electrical device, which can extend the cycle life of the battery.

[0006] In a first aspect, the present application provides a battery, comprising a positive electrode, a negative electrode, and a lithium-supplementing electrode, wherein the lithium-supplementing electrode is isolated from the positive electrode and the negative electrode; the lithium-supplementing electrode comprises a lithium-supplementing matrix and a protective layer coating the lithium-supplementing matrix; wherein the lithium-supplementing matrix contains a lithium-supplementing agent, and the protective layer has ionic conductivity.

[0007] In the battery of the embodiment of the present application, in addition to the positive electrode and the negative electrode, a lithium replenishing electrode is also provided. By coating the surface of the lithium replenishing agent in the lithium replenishing electrode with a protective layer having ionic conductivity, the lithium ions released by the lithium replenishing agent can be conducted, so that the lithium replenishing agent can smoothly provide lithium ions; and the protective layer can effectively inhibit the spontaneous side reaction between the lithium replenishing agent and the electrolyte, so that the lithium ions released by the lithium replenishing agent can be stably replenished into the positive electrode or the negative electrode, thereby recovering the capacity loss of the battery due to the loss of active lithium and extending the cycle life of the battery.

[0008] In some embodiments, the protective layer has a thickness of 1 to 30 μm, optionally 2 to 20 μm. At an appropriate protective layer thickness, the protective layer can effectively inhibit spontaneous side reactions between the lithium supplement agent and the electrolyte and effectively conduct lithium ions provided by the lithium supplement agent, thereby enabling lithium supplementation of the positive or negative electrode using the lithium supplement electrode, thereby extending the cycle life of the battery.

[0009] In some embodiments, the protective layer has an ionic conductivity of 0.05 to 20 mS / cm, optionally 0.47 to 0.72 mS / cm at 25° C. The protective layer of the present application has excellent ionic conductivity and can effectively conduct lithium ions released by the lithium supplement agent, allowing the lithium supplement agent to pass through the protective layer into the positive or negative electrode of the lithium supplement electrode.

[0010] In some embodiments, the protective layer comprises a solid electrolyte. A solid electrolyte is a solid substance that becomes conductive due to the movement of ions under the action of an electric field. It has excellent ion conductivity and can conduct lithium ions released by the lithium supplement during the lithium supplement process. It can also effectively inhibit spontaneous side reactions between the lithium supplement and the electrolyte.

[0011] In some embodiments, the mass content of the solid electrolyte in the protective layer is greater than 10%, optionally 50-100%. The content of the solid electrolyte in the protective layer affects the isolation effect of the protective layer on the lithium supplement and the electrolyte, as well as the ionic conductivity of the protective layer. At an appropriate solid electrolyte content, the protective layer can effectively inhibit the spontaneous side reactions between the lithium supplement and the electrolyte, and has sufficient ionic conductivity to effectively conduct the lithium ions provided by the lithium supplement, thereby realizing the lithium supplement of the positive or negative electrode using the lithium supplement electrode, thereby extending the cycle life of the battery.

[0012] In some embodiments, the solid electrolyte includes one or more of an inorganic solid electrolyte, a polymer solid electrolyte, and an inorganic-polymer composite solid electrolyte. Alternatively, the inorganic solid electrolyte includes one or more of lithium nitride, lithium oxynitride, lithium fluoride, lithium chloride, lithium phosphide, lithium oxide, lithium phosphate, lithium carbonate, nitrogen-containing lithium phosphate, garnet-type solid electrolyte, NASICON-type solid electrolyte, perovskite-type solid electrolyte, and antiperovskite-type solid electrolyte. Alternatively, the polymer solid electrolyte includes one or more of polyethylene, polypropylene, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, polyimide, polydimethylsiloxane, polymethyl methacrylate, lithiated acrylic acid, and lithiated perfluorosulfonic acid resin.

[0013] These solid electrolytes possess a certain lithium ion conductivity, allowing the lithium replenisher to penetrate the protective layer inside the lithium replenishing electrode and enter the positive or negative electrode. Furthermore, these solid electrolytes exhibit long-term physical and chemical stability within the battery system. They are not easily detached from the surface of the lithium replenisher, and possess excellent resistance to electrolyte corrosion and stability to the lithium replenisher. This allows them to continue functioning even after prolonged battery use or storage, facilitating long-term lithium replenishment and extending the battery's cycle life.

[0014] In some embodiments, the ratio between the capacity of the lithium supplement and the initial discharge capacity of the battery is 0.05 to 0.2, optionally 0.1 to 0.2. The ratio between the capacity of the lithium supplement and the initial discharge capacity of the battery is the capacity of the lithium supplement / initial discharge capacity of the battery. The capacity of the lithium supplement = the mass of the lithium supplement * the specific capacity of the lithium supplement. The initial discharge capacity of the battery is the discharge capacity obtained after the first cycle test, which is usually the highest discharge capacity shown by the battery. The attenuation of battery life means the loss of active lithium. For example, when the battery life decays to 80%, the loss of active lithium generally exceeds 10%. Therefore, when the capacity of the lithium supplement accounts for a certain proportion of the initial discharge capacity of the battery, the battery capacity can be restored after attenuation, thereby extending the battery life.

[0015] In some embodiments, the positive electrode comprises a positive electrode active material, the negative electrode comprises a negative electrode active material, and the lithium supplement agent has a potential lower than at least one of the positive electrode active material and the negative electrode active material. The lithium supplement electrode of the present application embodiment uses a low-potential lithium supplement agent. When the potential of the lithium supplement agent is lower than that of the positive electrode active material, the lithium supplement electrode is electrically connected to the positive electrode, and the lithium supplement agent can release lithium ions to supplement lithium to the positive electrode. When the potential of the lithium supplement agent is lower than that of the negative electrode active material, the lithium supplement electrode is electrically connected to the negative electrode, and the lithium supplement agent can release lithium ions to supplement lithium to the negative electrode. When the potential of the lithium supplement agent is lower than that of either the positive electrode active material or the negative electrode active material, the lithium supplement agent can be used to supplement lithium to both the positive electrode and the negative electrode.

[0016] In some embodiments, the lithium supplement comprises one or more of lithium, lithium alloys, and lithium-rich metal oxides. Among them, lithium alloys include alloys composed of lithium and one or more of Group IIA elements, Group IB-VIIIB elements, Group IIIA elements, and Group IVA elements. Among them, Group IIA elements include one or more of Be, Mg, Ca, Sr, and Ba; Group IB-VIIIB elements include one or more of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, La, Ag, and Au; Group IIIA elements include one or more of B, Al, Ga, and In; and Group IVA elements include one or more of Si, Ge, and Sn. Lithium-rich metal oxides refer to lithium metal oxides in which the molar ratio of lithium to other metals is greater than 1, and generally include various metal oxides formed by lithium and transition metals. These lithium-rich metal oxides may contain doping elements at one or more of the lithium, transition metal, and oxygen sites. Furthermore, the surface of these lithium-rich metal oxides may include one or more coating layers, which may have functions such as improving electrical conductivity and improving material structural stability. Lithium and many lithium alloys and lithium-rich metal oxides have lower potentials than common positive electrode active materials and / or negative electrode active materials of lithium secondary batteries. When the lithium replenishing electrode is electrically connected to the positive electrode or negative electrode, the lithium replenishing agent can release lithium ions to replenish lithium to the positive electrode or negative electrode.

[0017] In a second aspect, the present application provides a method for replenishing lithium in a battery, wherein the battery comprises a positive electrode, a negative electrode, and a lithium replenishing electrode, wherein the lithium replenishing electrode is isolated from the positive electrode and the negative electrode; the lithium replenishing electrode comprises a lithium replenishing matrix and a protective layer covering the lithium replenishing matrix; wherein the lithium replenishing matrix contains a lithium replenishing agent, and the protective layer has ionic conductivity;

[0018] The battery lithium replenishment method includes: electrically connecting the lithium replenishment electrode to the positive electrode or the negative electrode.

[0019] In the embodiments of the present application, a lithium-supplementing electrode is added to the battery in addition to the positive and negative electrodes. After the lithium-supplementing electrode is electrically connected to the positive or negative electrode, the lithium-supplementing electrode can release lithium ions. Furthermore, a protective layer is provided on the surface of the lithium-supplementing agent in the lithium-supplementing electrode. The protective layer has excellent ionic conductivity and can conduct the lithium ions released by the lithium-supplementing agent, allowing the lithium ions released by the lithium-supplementing agent to be smoothly replenished into the positive or negative electrode. Furthermore, the protective layer can effectively inhibit spontaneous side reactions between the lithium-supplementing agent and the electrolyte, allowing the lithium ions provided by the lithium-supplementing electrode to be stably replenished into the positive or negative electrode, thereby restoring the battery's capacity loss caused by the loss of active lithium and extending the battery's cycle life.

[0020] In some embodiments, after the lithium supplement electrode is electrically connected to the positive electrode or the negative electrode, the discharge current density through the surface of the lithium supplement electrode is greater than 0 and less than or equal to 5 mA·cm -2 , optionally 0.05~0.5mA·cm -2 Research has shown that under low current density, the lithium-replenishing electrode can effectively release lithium ions, and the lithium ions can effectively embed into the vacant lithium sites in the positive or negative electrode, thereby effectively replenishing lithium to the positive or negative electrode and extending the battery life.

[0021] In some embodiments, before electrically connecting the lithium replenishing electrode to the positive electrode, the step of adjusting the state of charge of the battery to 0-3% is included. Optionally, the state of charge is 0-1%. The state of charge (SOC) of the battery is adjusted to 0-3%, that is, the battery is in a fully discharged or nearly fully discharged state. Specifically, after discharging to the lower limit voltage with a current of 0.33C and leaving it for 30 minutes, the battery is further discharged to the lower limit voltage with a current of 0.04C. After leaving it for 30 minutes, the battery is discharged to the lower limit voltage with a current of 0.04C. After discharging three times with 0.04C, the battery is considered to be in a fully discharged or nearly fully discharged state. When the lithium replenishing electrode is electrically connected to the positive electrode in a fully discharged or nearly fully discharged state, the lithium replenishing agent in the lithium replenishing electrode can spontaneously release lithium ions to achieve positive electrode lithium replenishment.

[0022] In some embodiments, before electrically connecting the lithium-replenishing electrode to the negative electrode, the step of adjusting the state of charge of the battery to 97% to 100% is included. Optionally, the state of charge is 99% to 100%. The SOC of the battery is adjusted to 97% to 100%, that is, the battery is in a fully charged state. Specifically, after charging to the upper limit voltage with a current of 0.33C, it is left for 30 minutes, and constant voltage charging is performed at the upper limit voltage until the current drops to 0.04C. The battery is considered to be in a fully charged or nearly fully charged state. When the lithium-replenishing electrode is electrically connected to the negative electrode in a fully charged or nearly fully charged state, the lithium-replenishing agent in the lithium-replenishing electrode can spontaneously release lithium ions to achieve negative electrode lithium replenishment.

[0023] In some embodiments, before the lithium-supplementing electrode is electrically connected to the positive electrode or the negative electrode, the ratio of the discharge capacity of the battery to the initial discharge capacity is less than 1, optionally 0.7 to 0.9, which indicates that the battery has undergone capacity decay. At this time, there is a phenomenon of active lithium loss in the positive electrode or the negative electrode. In the case of full discharge / full charge, there are lattice vacancies in the positive electrode / negative electrode caused by lithium loss. In this case, the lithium-supplementing electrode is electrically connected to the positive electrode or the negative electrode, and the lithium-supplementing electrode can provide lithium ions to fill these lattice vacancies, thereby recovering the capacity loss of the battery caused by the loss of active lithium and extending the cycle life of the battery.

[0024] In a third aspect, the present application provides an electrical device, which includes the above-mentioned battery.

[0025] The battery disclosed in the embodiments of the present application can be used in electrical devices that use batteries as power sources, or in various energy storage systems that use batteries as energy storage elements, to provide electrical energy. The above-mentioned battery contains a lithium-supplementing electrode with a special structure. After the battery capacity has decayed to a certain extent, the lithium-supplementing electrode can be electrically connected to the positive electrode or the negative electrode, which is conducive to recovering the capacity loss of the battery due to the loss of active lithium and extending the cycle life of the battery. Therefore, using the above-mentioned battery to provide electrical energy for various electrical devices helps to extend the service life of the electrical devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0027] FIG1 is a schematic structural diagram of a lithium-supplementing electrode according to an embodiment of the present application;

[0028] FIG2 is a diagram showing the positional distribution relationship of the lithium-supplementing electrode tabs, the positive electrode tabs, and the negative electrode tabs in a battery according to one embodiment of the present application;

[0029] FIG3 is a schematic diagram of a battery according to an embodiment of the present application;

[0030] FIG4 is an exploded view of the battery shown in FIG3 according to one embodiment of the present application;

[0031] FIG5 is a schematic diagram of a battery module according to an embodiment of the present application;

[0032] FIG6 is a schematic diagram of a battery pack according to an embodiment of the present application;

[0033] FIG7 is an exploded view of the battery pack shown in FIG6 according to an embodiment of the present application;

[0034] FIG8 is a schematic diagram of an electrical device using a battery as a power source according to an embodiment of the present application.

[0035] Figure numerals: 10 - battery; 11 - lithium-replenishing electrode, 111 - lithium-replenishing electrode tab, 112 - lithium-replenishing agent, 113 - protective layer; 121 - positive electrode tab; 131 - negative electrode tab; 141 - shell, 142 - cover plate, 143 - electrode assembly; 101 - battery cell, 102 - battery module, 103 - battery pack, 1031 - upper case, 1032 - lower case. DETAILED DESCRIPTION

[0036] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0038] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0039] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0040] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0041] In the description of the embodiments of the present application, the term "at least one" refers to one or more, and "plurality" refers to two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple, respectively.

[0042] It should be understood that in the various embodiments of the present application, the size of the serial 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 sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0043] The weights of the relevant components mentioned in the examples of this application may not only refer to the specific content of each component, but also represent the weight ratio between the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the examples of this application, it is within the scope disclosed in the examples of this application. Specifically, the mass described in the examples of this application may be a mass unit known in the chemical industry, such as μg, mg, g, kg, etc.

[0044] With the continuous deepening of battery research and the continuous increase in market demand, various fields have put forward higher requirements for various battery performance, including cycle life, which has a significant impact on the user experience. The cycle life of a battery is the number of charge and discharge cycles that the battery can undergo while maintaining a certain capacity. In actual research and use, it has been found that after a certain number of cycles, the battery capacity tends to decay rapidly, and the cycle life is shortened.

[0045] There are many factors that affect the cycle life of batteries, including material type (such as electrode active materials, binders, conductive agents, electrolytes, solvents, additives, etc.), material usage, electrode compaction density, moisture, as well as human subjective factors in the battery production operation process, environmental factors, and objective factors of the battery system itself.

[0046] Among various factors, electrode active materials are a key factor and have been widely studied. For lithium-ion batteries, during the battery cycle, the electrolyte undergoes reduction and decomposition on the surface of the negative electrode, forming a solid electrolyte interface (SEI) film, which consumes a large amount of lithium ions from the positive electrode. Furthermore, the negative electrode active materials are typically expansive, placing the SEI film in a constant dynamic process of destruction and reconstruction, consuming more active lithium ions and causing the SEI film to increase in thickness and cross-sectional impedance, which in turn causes irreversible capacity decay and shortens the battery's cycle life.

[0047] To extend the cycle life of batteries, many studies have focused on increasing battery capacity by replenishing lithium. For example, by adding a lithium replenisher to the positive electrode, the lithium replenisher decomposes and releases active lithium during battery charging, compensating for the irreversible active lithium loss caused by the growth of the SEI film at the negative electrode. Alternatively, active lithium is introduced into the negative electrode through physical mixing, vacuum winding lithium plating, chemical lithiation, electrochemical lithiation, etc. to compensate for the capacity loss caused by SEI growth. Alternatively, a third electrode containing a lithium replenisher is provided in the battery in addition to the positive and negative electrodes, and the lithium replenishment effect is achieved by using this third electrode.

[0048] However, in reality, the lithium replenishing agents used in various lithium replenishing technologies are usually highly active and will produce side reactions with the electrolyte, which has limited effect on improving the battery cycle life.

[0049] To address the above problems, the embodiments of the present application provide an electrode with a lithium replenishing function (lithium replenishing electrode) in the battery. The lithium replenishing electrode contains a lithium replenishing agent, and a protective layer is provided on the surface of the lithium replenishing agent. The protective layer effectively inhibits the spontaneous side reaction between the lithium replenishing agent and the electrolyte, thereby helping to extend the cycle life of the battery.

[0050] The battery having the above structure can be applied to battery-powered electrical devices, such as, but not limited to, mobile phones, tablets, laptop computers, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, and the like. Electric toys may include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, and spacecraft may include airplanes, rockets, space shuttles, and spacecraft.

[0051] The present application will be further described below with reference to the following examples. It should be understood that these examples are only used to illustrate the present application and are not intended to limit the scope of the present application.

[0052] In a first aspect, an embodiment of the present application provides a battery, which includes a positive electrode, a negative electrode and a lithium-supplementing electrode, wherein the lithium-supplementing electrode is isolated from the positive electrode and the negative electrode; the lithium-supplementing electrode includes a lithium-supplementing matrix and a protective layer covering the lithium-supplementing matrix; wherein the lithium-supplementing matrix contains a lithium-supplementing agent, and the protective layer has ionic conductivity.

[0053] Batteries are classified into battery cells, battery modules, and battery packs according to different packaging formats. The batteries of the embodiments of the present application may be any one or more of the battery cells, battery modules, and battery packs.

[0054] The lithium replenishing electrode is isolated from the positive electrode and the negative electrode, which means that the lithium replenishing electrode and the positive electrode and the negative electrode do not contact each other, including the isolation between the lithium replenishing electrode and the positive electrode, the isolation between the lithium replenishing electrode and the negative electrode, and the isolation between the positive electrode and the negative electrode.

[0055] A lithium supplement is a substance that can provide active lithium ions. The lithium supplement of the embodiment of the present application can have any one or more structures of block, sheet, and granular. In the case where the lithium supplement is a block or sheet structure, the lithium supplement itself can serve as a lithium supplement matrix; in this case, the protective layer coats the lithium supplement matrix, and the protective layer can be coated on the surface of a block or sheet-shaped integrated lithium supplement. As shown in FIG1 , the lithium supplement electrode 11 includes a lithium supplement matrix containing a lithium supplement 112 and a protective layer 113 coating the lithium supplement matrix. In the case where the lithium supplement is a granular structure, the lithium supplement with a granular structure can be formed (for example, rolled alone, or rolled after adding a binder and mixing) to form a lithium supplement matrix.

[0056] In the battery of the embodiment of the present application, in addition to the positive electrode and the negative electrode, a lithium replenishing electrode is also provided. By coating the surface of the lithium replenishing agent in the lithium replenishing electrode with a protective layer having ionic conductivity, the lithium ions released by the lithium replenishing agent can be conducted, so that the lithium replenishing agent can smoothly provide lithium ions; and the protective layer can effectively inhibit the spontaneous side reaction between the lithium replenishing agent and the electrolyte, so that the lithium ions released by the lithium replenishing agent can be stably replenished into the positive electrode or the negative electrode, thereby recovering the capacity loss of the battery due to the loss of active lithium and extending the cycle life of the battery.

[0057] The characteristics of each component in the battery of the embodiment of the present application, such as structure, chemical composition, etc., are described below.

[0058]

Lithium Supplement Electrode

[0059] 1. Protective layer

[0060] In some embodiments, the thickness of the protective layer is 1 to 30 μm, optionally 2 to 20 μm, including but not limited to any one of 1 μm, 2 μm, 4 μm, 6 μm, 8 μm, 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, 20 μm, 22 μm, 24 μm, 26 μm, 28 μm, and 30 μm, or a range of values ​​between any two of them. The thickness of the protective layer can be measured under an electron microscope such as a scanning electron microscope. At an appropriate protective layer thickness, the protective layer can effectively inhibit the spontaneous side reaction of the lithium supplement agent with the electrolyte, and effectively conduct the lithium ions provided by the lithium supplement agent, thereby achieving lithium supplementation of the positive electrode or negative electrode using the lithium supplement electrode, thereby extending the cycle life of the battery.

[0061] In some embodiments, the ionic conductivity of the protective layer is 0.05 to 20 mS / cm (25° C.), optionally 0.47 to 0.72 mS / cm. For example, the ionic conductivity of the protective layer includes, but is not limited to, any one of 0.05 mS / cm, 0.1 mS / cm, 0.2 mS / cm, 0.4 mS / cm, 0.47 mS / cm, 0.6 mS / cm, 0.72 mS / cm, 0.8 mS / cm, 1 mS / cm, 2 mS / cm, 4 mS / cm, 6 mS / cm, 8 mS / cm, 10 mS / cm, 12 mS / cm, 14 mS / cm, 16 mS / cm, 18 mS / cm, and 20 mS / cm, or a range of values ​​between any two of them. The ionic conductivity of the protective layer refers to the conductivity of the protective layer to ions, and can reflect the conductivity of the protective layer to ions. The ionic conductivity of the protective layer can be measured by the following method: after gold spraying the surface of the protective layer, the protective layer is assembled into a blocked electrode system. A certain alternating current is applied to the blocked electrode system to obtain an AC impedance spectrum. The spectrum data is then analyzed to determine the total impedance contributed by the protective layer itself. The ionic conductivity is calculated based on the sample size of the protective layer. The protective layer of the embodiment of the present application has excellent ionic conductivity and can effectively conduct lithium ions released by the lithium supplement agent, allowing the lithium ions provided by the lithium supplement agent to pass through the protective layer from the interior of the lithium supplement electrode to the positive or negative electrode.

[0062] In some embodiments, the protective layer comprises a solid electrolyte. A solid electrolyte is a solid substance that becomes conductive due to the movement of ions under the action of an electric field. It has excellent ion conductivity and can conduct lithium ions released by the lithium supplement during the lithium supplement process. It can also effectively inhibit spontaneous side reactions between the lithium supplement and the electrolyte.

[0063] In some embodiments, the mass content of the solid electrolyte in the protective layer is greater than 10%, optionally 50-100%, and further optionally 85%-100%, including but not limited to any one of 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 100%, or any range between two of them. The content of the solid electrolyte in the protective layer affects the isolation effect of the protective layer on the lithium supplement and the electrolyte and the ionic conductivity of the protective layer. At an appropriate solid electrolyte content, the protective layer can effectively inhibit the spontaneous side reaction of the lithium supplement and the electrolyte, and has sufficient ionic conductivity to effectively conduct the lithium ions provided by the lithium supplement, thereby realizing the lithium supplement of the positive or negative electrode using the lithium supplement electrode, thereby extending the cycle life of the battery.

[0064] In some embodiments, the solid electrolyte includes one or more of an inorganic solid electrolyte, a polymer solid electrolyte, and an inorganic-polymer composite solid electrolyte.

[0065] Among them, the inorganic solid electrolyte includes but is not limited to one or more of lithium nitride, lithium oxynitride, lithium fluoride, lithium chloride, lithium phosphide, lithium oxide, lithium phosphate, lithium carbonate, nitrogen-containing lithium phosphate, garnet-type solid electrolyte, NASICON-type solid electrolyte, perovskite-type solid electrolyte, and antiperovskite-type solid electrolyte. Among them, the garnet-type solid electrolyte is a kind of solid electrolyte with the chemical formula Li 7-x La 3-a Zr 2-b O 12 {x=[0,3],a=[0,3],b=[0,0.2]}, or in formula Li 7-x La 3-a Zr 2-b O 12 Other metal elements (such as one or more of La, Nb, Ta, Ga, Cr, Al, W, Ca, for example, Li 6.5 La3Zr2Ta 0.5 O 12 ) lithium lanthanum zirconium oxide compound; NASICON type solid electrolyte is a kind of solid electrolyte with Na 1+x Zr2Si x P 3-x O 12 {x=[0,3]} Fast ion conductors with similar crystal structures, such as Li 1.3-y Al 0.3-c Ti 1.7-d (PO4)3{LATP, y=[0, 0.3], c=[0, 0.05], d=[0, 0.7]}, Li 1.5 Al 0.5 Ge 1.5 (PO4)3(LAGP).

[0066] The polymer solid electrolyte includes, but is not limited to, one or more of polyethylene, polypropylene, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, polyimide, polydimethylsiloxane, polymethyl methacrylate, lithiated acrylic acid, and lithiated perfluorosulfonic acid resin.

[0067] The inorganic-polymer composite solid electrolyte includes a composite solid electrolyte formed by any one or more of the above-mentioned inorganic solid electrolytes and any one or more polymer solid electrolytes.

[0068] These solid electrolytes possess a certain lithium-ion conductivity, allowing the lithium ions provided by the lithium supplement to pass through the protective layer from the interior of the lithium supplement electrode into the positive or negative electrode. Furthermore, these solid electrolytes exhibit long-term physical and chemical stability within the battery system. They are not easily detached from the surface of the lithium supplement, and possess good resistance to electrolyte corrosion and stability to the lithium supplement. This allows them to continue functioning even after prolonged battery use or storage, facilitating long-term lithium supplementation and extending the battery's cycle life.

[0069] 2. Lithium-supplemented matrix

[0070] The active ingredient in the lithium-supplementing electrode of the present embodiment is mainly a lithium-supplementing agent. Some important features of the lithium-supplementing matrix or the lithium-supplementing agent contained therein are as follows:

[0071] In some embodiments, the ratio of the capacity of the lithium supplement to the initial discharge capacity of the battery is 0.05 to 0.2, optionally 0.1 to 0.2, and may include, but is not limited to, any point value among 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.12, 0.14, 0.16, 0.18, and 0.2, or a range of values ​​between any two of them. The ratio of the capacity of the lithium supplement to the initial discharge capacity of the battery is calculated as follows: capacity of the lithium supplement / initial discharge capacity of the battery. The capacity of the lithium supplement = mass of the lithium supplement * specific capacity of the lithium supplement. The initial discharge capacity of the battery is the discharge capacity obtained after the first cycle test, which is usually the highest discharge capacity exhibited by the battery. Battery life decay means that active lithium has been lost. For example, when the battery life decays to 80%, the loss of active lithium generally exceeds 10%. Therefore, when the capacity of the lithium supplement accounts for a certain proportion of the initial discharge capacity of the battery, the battery capacity can be restored after decay, thereby extending the battery life.

[0072] In some embodiments, the positive electrode includes a positive electrode active material, the negative electrode includes a negative electrode active material, and the lithium supplement has a potential lower than at least one of the positive electrode active material and the negative electrode active material; optionally, the lithium supplement has a potential lower than either the positive electrode active material or the negative electrode active material. The lithium supplement electrode of the embodiment of the present application uses a low-potential lithium supplement. When the potential of the lithium supplement is lower than that of the positive electrode active material, the lithium supplement electrode is electrically connected to the positive electrode, and the lithium supplement can release lithium ions to supplement lithium to the positive electrode; when the potential of the lithium supplement is lower than that of the negative electrode active material, the lithium supplement electrode is electrically connected to the negative electrode, and the lithium supplement can release lithium ions to supplement lithium to the negative electrode; and when the potential of the lithium supplement is lower than either the positive electrode active material or the negative electrode active material, the lithium supplement can be used to supplement lithium to both the positive electrode and the negative electrode.

[0073] In some embodiments, the lithium supplement comprises one or more of lithium, lithium alloys, and lithium-rich metal oxides. Among them, lithium alloys include alloys composed of lithium and one or more of Group IIA elements, Group IB-VIIIB elements, Group IIIA elements, and Group IVA elements. Among them, Group IIA elements include one or more of Be, Mg, Ca, Sr, and Ba; Group IB-VIIIB elements include one or more of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, La, Ag, and Au; Group IIIA elements include one or more of B, Al, Ga, and In; and Group IVA elements include one or more of Si, Ge, and Sn. Lithium-rich metal oxides refer to lithium metal oxides in which the molar ratio of lithium to other metals is greater than 1, and generally include various metal oxides formed by lithium and transition metals. These lithium-rich metal oxides may contain doping elements at one or more of the lithium, transition metal, and oxygen sites. Furthermore, the surface of these lithium-rich metal oxides may include one or more coating layers, which may have functions such as improving electrical conductivity and improving material structural stability. Lithium and many lithium alloys and lithium-rich metal oxides have lower potentials than common positive electrode active materials and / or negative electrode active materials of lithium secondary batteries. When the lithium replenishing electrode is electrically connected to the positive electrode or negative electrode, the lithium replenishing agent can release lithium ions to replenish lithium to the positive electrode or negative electrode.

[0074] 3. Binder and current collector

[0075] In addition to the features mentioned above, the protective layer and the lithium-replenishing matrix may also include the following optional features:

[0076] In some embodiments, the protective layer optionally contains a binder. In the case where the solid electrolyte used in the protective layer itself does not have adhesive properties, or its own adhesive properties are weak, a binder can be added to the protective layer; in the case where the solid electrolyte used in the protective layer itself has good adhesive properties, the protective layer may not contain a binder. The binder can enhance the bonding strength between the protective layer and the lithium supplement. The binder may include, but is not limited to, one or more of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, polyimide, polybutyl acrylate, carboxymethyl cellulose, carboxymethyl cellulose salt, polyacrylic acid, polyacrylate, and polyvinyl alcohol.

[0077] In some embodiments, the mass content of the binder in the protective layer is 0-15%, optionally 1%-5%, for example, any point value among 0, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15% or a range value between any two of them, and can also be set to other contents as needed.

[0078] In some embodiments, the lithium supplement matrix may further include a current collector, and the lithium supplement agent is distributed on at least one side of the current collector. The lithium supplement agent of the embodiment of the present application includes one or more of lithium, lithium alloy, and lithium-rich metal oxide, and may have a block, sheet, granular, and other structures. When the lithium supplement agent has a block or sheet structure and has good electrical conductivity, for example, the lithium supplement agent is a block or sheet lithium or lithium alloy, the lithium supplement matrix may not include a current collector. When the lithium supplement agent is in a granular structure, or the lithium supplement agent itself does not have electrical conductivity or has poor electrical conductivity (for example, the lithium supplement agent is a lithium-rich metal oxide), the lithium supplement matrix may include a current collector, which is used to collect the current in the lithium supplement electrode and improve the electrical conductivity of the lithium supplement electrode. The current collector in the lithium supplement matrix may include but is not limited to a metal current collector, a carbon current collector, a conductive resin current collector, a composite current collector of metal and resin, and more specifically, aluminum, copper, nickel, titanium, iron, and their respective alloys, stainless steel, carbon fiber, carbon nanotubes (CNT), graphite, and the like.

[0079] 4. Preparation of Lithium-Supplementing Electrode

[0080] The lithium-supplementing electrode of the embodiment of the present application can be prepared by referring to the following method:

[0081] In the case where the lithium supplement agent has a block or sheet structure, the lithium supplement agent alone can form a lithium supplement matrix. The preparation method of the lithium supplement electrode includes: coating a protective layer raw material on the surface of the lithium supplement agent. Among them, the protective layer raw material includes the above-mentioned solid electrolyte and may also contain a binder. After the coating step, it can also be dried and rolled as needed to form a lithium supplement electrode sheet. A section of the lithium supplement agent with a block or sheet structure is connected (such as welding) to a pole ear (such as nickel) to obtain a complete lithium supplement electrode.

[0082] In the case where the lithium supplement agent has a granular structure, the preparation method of the lithium supplement electrode includes: forming the granular lithium supplement agent (for example, rolling it alone or adding a binder and then rolling it) to obtain a lithium supplement matrix, and then coating the protective layer material on the surface of the lithium supplement matrix; or coating the granular lithium supplement agent (alone or mixed with a binder) on the surface of the current collector to form a lithium supplement matrix, and then coating the protective layer material on the surface of the lithium supplement matrix. In this way, a lithium supplement electrode plate can be produced. The lithium supplement matrix or current collector in the lithium supplement electrode plate is connected to the pole tab to produce a complete lithium supplement electrode.

[0083] [Positive electrode, negative electrode]

[0084] In some embodiments, the positive electrode includes a positive electrode active layer, the positive electrode active layer contains a positive electrode active material, and the positive electrode active material includes but is not limited to one or more of LiFePO4, Li3V2(PO4)3, LiMn2O4, LiMnO2, LiNiO2, LiCoO2, LiVPO4F, LiFeO2, Li 1+x L 1-y-z M 1 y M 2 z O2, where -0.1 ≤ x ≤ 0.2, 0 ≤ y ≤ 1, 0 ≤ z ≤ 1, 0 ≤ y + z ≤ 1, and L, M 1 、M 2 each independently includes one or more of Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Mg, Ga.

[0085] In some embodiments, the mass content of the positive electrode active material in the positive electrode active layer includes but is not limited to 90% to 98%, such as 95% to 98%, for example, any one point value or the range value between any two of 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, and can also be set to other contents as needed.

[0086] In some embodiments, the negative electrode includes a negative electrode active layer, the negative electrode active layer contains a negative electrode active material, and the negative electrode active material includes but is not limited to natural graphite, artificial graphite, mesophase carbon microspheres, hard carbon, soft carbon, silicon, SiO x (0 < x ≤ 2), silicon carbide, lithium titanate (Li4Ti5O 12 ).

[0087] In some embodiments, the mass content of the negative electrode active material in the negative electrode active layer includes but is not limited to 90% to 98%, such as 95% to 98%, for example, any one point value or the range value between any two of 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, and can also be set to other contents as needed.

[0088] In some embodiments, the positive electrode active layer and the negative electrode active layer each independently further include one or more of a conductive agent and a binder. The conductive agent is used to collect microcurrents between the active materials and between the active materials and the current collector, improve the electronic conductivity, and at the same time, the conductive agent can also promote the infiltration of the electrolyte into the positive electrode or the negative electrode. The binder can improve the binding strength between the substances in the active layer and between the active layer and the current collector.

[0089] In some embodiments, the conductive agent includes one or more of acetylene black (SP), carbon nanotubes, conductive carbon black (super-P), Ketjen black, carbon fiber, and graphene.

[0090] In some embodiments, the mass content of the conductive agent in the positive electrode active layer or the negative electrode active layer includes but is not limited to 0.5% to 10%, such as 1% to 5%, for example, any one of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10% or a range between any two of them, and can also be set to other contents as needed.

[0091] In some embodiments, the binders in the positive electrode active layer and the negative electrode active layer independently include, but are not limited to, one or more of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, polyimide, polytetrafluoroethylene, polybutyl acrylate, polyacrylonitrile, carboxymethyl cellulose, carboxymethyl cellulose salt, polyacrylic acid, polyacrylate, polyvinyl alcohol, sodium alginate, cyclodextrin, styrene-butadiene rubber, vinyl acetate resin, acrylic resin, and chlorinated rubber.

[0092] In some embodiments, the mass content of the binder in the positive electrode active layer or the negative electrode active layer is independently 0.5% to 15%, optionally 1% to 5%, for example, any one of 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15% or a range between any two of them, and can also be set to other contents as needed.

[0093] In some embodiments, the positive electrode active layer and the negative electrode active layer each independently further include a thickener, such as carboxymethyl cellulose (CMC). The mass content of the thickener in the positive electrode active layer and the negative electrode active layer each independently includes, but is not limited to, 0.5% to 5%, such as 1% to 5%, including but not limited to any one of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, and 5%, or a range between any two of the values, and may also be set to other content as needed.

[0094] In some embodiments, the positive electrode and the negative electrode each independently further include a current collector. The current collector is used to transport electrons. Typically, the active layer is provided on at least one side of the current collector. The current collectors of the positive electrode and the negative electrode each independently include, but are not limited to, metal current collectors, carbon current collectors, conductive resin current collectors, composite current collectors of metal and resin, and more specifically, aluminum, copper, nickel, titanium, iron, and their respective alloys, stainless steel, carbon fiber, carbon nanotubes (CNTs), graphite, and the like. Optionally, the current collector of the positive electrode includes aluminum and the current collector of the negative electrode includes copper.

[0095] [Positional relationship between lithium supplement electrode and positive and negative electrodes]

[0096] The lithium supplement electrode is isolated from the positive and negative electrodes. For example, a separator can be used to separate the three electrodes from each other, preventing them from contacting each other. This isolation prevents battery short circuits caused by contact between the electrodes.

[0097] Specifically, the lithium-supplementing electrode includes a lithium-supplementing electrode tab and a lithium-supplementing electrode plate. The lithium-supplementing electrode plate includes the above-mentioned lithium-supplementing agent and a protective layer (optionally, it may also include a current collector). The lithium-supplementing electrode tab protrudes from the edge of the lithium-supplementing electrode plate in a direction away from the lithium-supplementing electrode plate (referring to FIG. 1 , the lithium-supplementing electrode 11 includes a lithium-supplementing electrode tab 111, a lithium-supplementing matrix containing a lithium-supplementing agent 112, and a protective layer 113 covering the lithium-supplementing matrix to form the lithium-supplementing electrode plate);

[0098] The positive electrode includes a positive electrode tab and a positive electrode sheet. The positive electrode sheet includes the above-mentioned current collector and positive electrode active layer. The positive electrode tab protrudes from the edge of the positive electrode sheet in a direction away from the positive electrode sheet.

[0099] The negative electrode includes a negative electrode tab and a negative electrode sheet. The negative electrode sheet includes the above-mentioned current collector and negative electrode active layer. The negative electrode tab protrudes from the edge of the negative electrode sheet in a direction away from the negative electrode sheet.

[0100] The lithium replenishing electrode plate, the positive electrode plate, and the negative electrode plate are isolated from each other. For example, a diaphragm can be used to isolate the three from each other and prevent them from contacting each other. At the same time, all three are immersed in the electrolyte of the battery.

[0101] The lithium-replenishing electrode tab, the positive electrode tab, and the negative electrode tab can be in contact with the electrolyte, are isolated from each other, and can be positioned in any direction within the battery. For example, referring to FIG2a, the lithium-replenishing electrode tab 111 can be positioned solely on one side of the battery 10, while the positive electrode tab 121 and the negative electrode tab 131 can be positioned on the other side opposite the protruding direction of the lithium-replenishing electrode tab 111. Referring to FIG2b, the lithium-replenishing electrode tab 111, the positive electrode tab 121, and the negative electrode tab 131 can be positioned solely on one side of the battery 10. Referring to FIG2c, the lithium-replenishing electrode tab 111, the positive electrode tab 121, and the negative electrode tab 131 can be positioned on the same side of the battery 10.

[0102] In the actual application of the battery, the lithium-replenishing electrode tab 111 can be electrically connected to the positive electrode tab 121 as needed to achieve positive electrode lithium replenishment; or the lithium-replenishing electrode tab 111 can be electrically connected to the negative electrode tab 131 to achieve negative electrode lithium replenishment. That is to say, it is possible to choose whether to electrically connect the lithium-replenishing electrode tab 111 to the positive electrode tab 121 or the negative electrode tab 131 according to actual needs. Therefore, the lithium-replenishing electrode tab 111 can be set at the same position from the positive electrode tab 121 and the negative electrode tab 131. Among them, the electrical connection referred to in the embodiment of the present application refers to a circuit connection, that is, a connection through a physical line that can transmit electrical signals such as a conductor or a wire, and the conductor or wire needs to have direct physical contact with different components (such as the lithium-replenishing electrode tab, the positive electrode tab, and the negative electrode tab). In particular, the electrical connection between the lithium replenishment electrode tab 111 and the positive electrode tab 121 or the negative electrode tab 131 needs to be controlled by the battery management system (BMS) to control the current passing through the lithium replenishment electrode to be within an appropriate range to achieve controllable lithium replenishment.

[0103] [Electrolyte]

[0104] In some embodiments, the battery further includes an electrolyte, and the positive electrode, negative electrode, and lithium-supplementing electrode are all in contact with the electrolyte (specifically, the lithium-supplementing electrode plate, the positive electrode plate, and the negative electrode plate are all immersed in the battery's electrolyte). In the battery, the electrolyte can serve as a carrier for conducting ions between the electrodes. The electrolyte can include a solvent and a lithium salt dissolved in the solvent.

[0105] The solvent in the electrolyte may be a non-aqueous organic solvent, such as one or more of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB) and ethyl butyrate (EB).

[0106] The lithium salt may be one or more of LiPF6 (lithium hexafluorophosphate), LiBF4 (lithium tetrafluoroborate), LiClO4 (lithium perchlorate), LiAsF6 (lithium hexafluoroarsenate), LiFSI (lithium bis(fluorosulfonyl)imide), LiTFSI (lithium bis(trifluoromethanesulfonyl)imide), LiOTf (lithium trifluoromethanesulfonate), LiDFOB (lithium difluorooxalatoborate), LiBOB (lithium bis(oxalatoborate), LiPO2F2 (lithium difluorophosphate), LiDFOP (lithium difluorooxalatophosphate) and LiTFOP (lithium tetrafluorooxalatophosphate), for example, one or more of LiPF6 (lithium hexafluorophosphate), LiBF4 (lithium tetrafluoroborate), LiBOB (lithium bis(oxalatoborate), LiDFOB (lithium difluorooxalatoborate), LiTFSI (lithium bis(trifluoromethanesulfonyl)imide) and LiFSI (lithium bis(fluorosulfonyl)imide).

[0107] The electrolyte may also optionally contain other additives, such as vinylene carbonate (VC), vinyl ethylene carbonate (VEC), fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoromethylethylene carbonate (TFPC), succinonitrile (SN), adiponitrile (ADN), glutaronitrile (GLN), hexanetrinitrile (HTN), 1,3-propane sultone (1,3-PS), vinyl sulfate (DTD), methylene disulfonate (MMDS), 1-propylene-1,3-sultone (PST), 4-methylethylene sulfate (PCS), 4-ethylethylene sulfate (PES), 4-propylethylene sulfate (PEGLST), propylene sulfate (TS), 1,4-butane sultone (1,4-BS), ethylene sulfite (DTO), dimethyl sulfite (DMS), diethyl sulfite (DES), sulfonate cyclic quaternary ammonium salt, tris(trimethylsilyl) phosphate (TMSP) and tris(trimethylsilyl) borate (TMSB), but are not limited thereto.

[0108] [Diaphragm]

[0109] In some embodiments, the battery further comprises a separator disposed between any two of the positive electrode, negative electrode, and lithium-supplementing electrode. Separators are disposed between the lithium-supplementing electrode and the positive electrode, between the lithium-supplementing electrode and the negative electrode, and between the positive and negative electrodes. These separators separate the electrodes, preventing electrons from freely passing through the battery and short-circuiting the electrodes. Separators also allow ions in the battery electrolyte to freely pass between the lithium-supplementing electrode and the positive electrode, and between the lithium-supplementing electrode and the negative electrode.

[0110] The diaphragm can be any known porous structure separator with electrochemical stability and mechanical stability, such as single-layer or multi-layer films of one or more of glass fiber, non-woven fabric, polyethylene (PE), polypropylene (PP) and polyvinylidene fluoride (PVDF).

[0111]

Outer packaging

[0112] In some embodiments, the battery may include an outer packaging that can be used to encapsulate an electrode assembly including a positive electrode, a negative electrode, a lithium-supplementing electrode, a separator, and an electrolyte.

[0113] The battery outer packaging can be a hard shell, such as a hard plastic shell, aluminum shell, or steel shell; or a soft shell, such as a pouch-type soft shell. The soft shell can be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0114] The outer packaging of the battery can be cylindrical, square or any other shape. For example, FIG3 is an example of a battery with a square outer packaging.

[0115] In some embodiments, referring to FIG4 , the outer packaging may include a shell 141 and a cover plate 142 . Specifically, the shell 141 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity. The shell 141 has an opening connected to the receiving cavity, and the cover plate 142 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet, the lithium supplement electrode, and the separator can be formed into an electrode assembly 143 through a winding process or a lamination process. One or more electrode assemblies 143 are encapsulated in the receiving cavity. The electrolyte is infiltrated into the electrode assembly 143.

[0116]

Battery cells, battery modules, battery packs

[0117] The battery of the embodiment of the present application includes one or more of a battery cell, a battery module, and a battery pack.

[0118] According to the different packaging forms, secondary batteries are divided into battery cells, battery modules, and battery packs. Among them, the battery cell is the most basic unit of the secondary battery, including the electrode assembly and electrolyte. The electrode assembly usually includes a positive electrode, a negative electrode, a lithium-supplementing electrode, and a separator. The positive and negative electrodes are alternately stacked, and a separator is provided between the positive and negative electrodes to play a role of isolation, thereby obtaining a bare cell, or a bare cell obtained by winding. The bare cell is placed in an outer packaging, injected with electrolyte, and sealed together with the lithium-supplementing electrode to obtain a battery cell.

[0119] One or more battery cells are combined to form a battery module, which can provide higher voltage and capacity, with a specific functional output. One or more battery modules are installed in a battery housing, often with a battery management system, to form a battery pack. This battery pack is typically provided to the user. Alternatively, one or more battery cells can be directly installed in a housing to form a battery pack.

[0120] Referring to Figure 5 , an example battery module 102 is shown. Within the battery module 102 , multiple battery cells 101 may be arranged sequentially along the length of the battery module 102 . Alternatively, the arrangement may be arranged in any other manner. Furthermore, the multiple battery cells 101 may be secured together using fasteners.

[0121] Optionally, the battery module 102 may further include a housing having an accommodation space, and the plurality of battery cells 101 may be accommodated in the accommodation space.

[0122] Refer to Figures 6 and 7, which illustrate an example battery pack 103. The battery pack 103 may include a battery box and multiple battery modules 102 disposed within the battery box. The battery box includes an upper case 1031 and a lower case 1032. The upper case 1031 can be placed over the lower case 1032 to form an enclosed space for accommodating the battery modules 102. The multiple battery modules 102 can be arranged in any manner within the battery box.

[0123]

Battery lithium replenishment method

[0124] Based on the above-mentioned battery, a second aspect of an embodiment of the present application further provides a battery lithium replenishment method, which includes: electrically connecting a lithium replenishment electrode to a positive electrode or a negative electrode.

[0125] Electrical connection refers to circuit connection, that is, connection through physical lines such as conductors or wires that can transmit electrical signals. The conductors or wires need to have direct physical contact with different components. Electrically connecting the lithium supplement electrode to the positive or negative electrode means connecting the output terminal (lithium supplement electrode tab) of the lithium supplement electrode to the output terminal (positive electrode tab) of the positive electrode or the output terminal (negative electrode tab) of the negative electrode through a conductor or wire. During the electrical connection, the current can be controlled by the battery management system (BMS).

[0126] In the embodiments of the present application, a lithium-supplementing electrode is added to the battery in addition to the positive and negative electrodes. After the lithium-supplementing electrode is electrically connected to the positive or negative electrode, the lithium-supplementing electrode can release lithium ions. Furthermore, a protective layer is provided on the surface of the lithium-supplementing agent in the lithium-supplementing electrode. The protective layer has excellent ionic conductivity and can conduct the lithium ions released by the lithium-supplementing agent, allowing the lithium ions released by the lithium-supplementing agent to be smoothly replenished into the positive or negative electrode. Furthermore, the protective layer can effectively inhibit spontaneous side reactions between the lithium-supplementing agent and the electrolyte, allowing the lithium ions provided by the lithium-supplementing electrode to be stably replenished into the positive or negative electrode, thereby restoring the battery's capacity loss caused by the loss of active lithium and extending the battery's cycle life.

[0127] In some embodiments, after the lithium supplement electrode is electrically connected to the positive electrode or the negative electrode, the discharge current density (J) through the surface of the lithium supplement electrode is greater than 0 and less than or equal to 5 mA·cm -2, optionally 0.05~0.5mA·cm -2 , and optionally 0.05 to 0.2 mA·cm -2 For example, the discharge current density J may include but is not limited to 0.05 mA·cm -2 , 0.1 mA·cm -2 , 0.15 mA·cm -2 , 0.2 mA·cm -2 , 0.25 mA·cm -2 , 0.3 mA·cm -2 , 0.35 mA·cm -2 , 0.4 mA·cm -2 , 0.45 mA·cm -2 , 0.5 mA·cm -2 , 1mA·cm -2 , 1.5 mA·cm -2 , 2mA·cm -2 , 2.5mA·cm -2 , 3mA·cm -2 , 3.5 mA·cm -2 , 4mA·cm -2 , 4.5 mA·cm -2 , 5mA·cm -2 Any point value or the range value between any two of them. After the lithium-supplementing electrode is electrically connected to the positive electrode or the negative electrode, a primary battery is formed, and a discharge process is spontaneously generated to form a discharge current. That is, the lithium-supplementing electrode acts as a negative electrode, spontaneously releasing lithium ions, and the lithium ions are embedded in the positive electrode or the negative electrode after conduction of the electrolyte. The discharge current density can be monitored and controlled by a test instrument with current testing and control functions, such as a current control instrument, a battery testing system, etc. According to research, under low current density, the lithium-supplementing electrode can effectively release lithium ions, and lithium ions can be effectively embedded in the vacant lithium sites in the positive electrode or the negative electrode, thereby effectively replenishing lithium to the positive electrode or the negative electrode and extending the battery life.

[0128] In some embodiments, while the lithium-supplementing electrode is electrically connected to the positive electrode or negative electrode, the electrical connection between the positive electrode and the negative electrode is disconnected. This allows for a smooth electrochemical reaction between the lithium-supplementing electrode and the positive electrode or negative electrode, achieving lithium replenishment of the positive electrode or negative electrode using the lithium-supplementing electrode without causing a short circuit between the electrodes.

[0129] In some embodiments, before electrically connecting the lithium supplement electrode to the positive electrode, the step of adjusting the state of charge of the battery to 0-3% is included. Optionally, the state of charge is 0-1%, such as any one of 0, 0.5%, 1%, 1.5%, 2%, 2.5%, and 3%, or a range of values ​​between any two of them. The state of charge (SOC) is the ratio of the remaining capacity of the battery to its capacity in a fully charged state. Adjusting the SOC of the battery to 0-3% means that the battery is in a fully discharged or nearly fully discharged state. Specifically, after discharging to the lower limit voltage with a current of 0.33C and leaving it for 30 minutes, the battery is further discharged to the lower limit voltage with a current of 0.04C. After leaving it for 30 minutes, the battery is discharged to the lower limit voltage with a current of 0.04C. After discharging at 0.04C three times, the battery is considered to be in a fully discharged or nearly fully discharged state. The lower limit voltage refers to the lowest voltage in the operating voltage range of the battery. Different battery systems have different operating voltages and their lower limit voltages are also different. For example, for a lithium-ion battery system using a ternary cathode material, the operating voltage range is generally 2.5 to 4.2 (or 4.3, 4.4) V, and its lower limit voltage is 2.5 V. For a lithium-ion battery system using lithium iron phosphate (LFP) cathode material, the operating voltage range is generally 2 to 3.65 (or 3.8) V, and its lower limit voltage is 2 V. When the lithium replenishing electrode is electrically connected to the positive electrode in a fully or nearly fully discharged state, the lithium replenishing agent in the lithium replenishing electrode can spontaneously release lithium ions, thereby achieving lithium replenishment at the positive electrode.

[0130] In some embodiments, before electrically connecting the lithium supplement electrode to the negative electrode, the step of adjusting the SOC of the battery to 97% to 100% is included. Optionally, the state of charge is 99% to 100%, for example, any one of 97%, 97.5%, 98%, 98.5%, 99%, 99.5%, 100%, or a range of values ​​between any two of them. The SOC of the battery is adjusted to 97% to 100%, that is, the battery is in a fully charged or nearly fully charged state. Specifically, after charging to the upper limit voltage with a current of 0.33C and then standing for 30 minutes, and performing constant voltage charging at the upper limit voltage until the current drops to 0.04C, the battery is considered to be in a fully charged or nearly fully charged state. The upper limit voltage refers to the highest voltage in the battery operating voltage range. For example, for a lithium-ion battery system using a ternary cathode material, the operating voltage range is generally 2.5 to 4.2 (or 4.3, 4.4) V, and the upper limit voltage is 4.2 (or 4.3, 4.4) V. For a lithium-ion battery system using lithium iron phosphate (LFP) cathode material, the operating voltage range is generally 2 to 3.65 (or 3.8) V, and the upper limit voltage is 3.65 (or 3.8) V. When the lithium replenishing electrode is electrically connected to the negative electrode in a fully charged or nearly fully charged state, the lithium replenishing agent in the lithium replenishing electrode can spontaneously release lithium ions, thereby achieving lithium replenishment at the negative electrode.

[0131] In some embodiments, before the lithium-supplementing electrode is electrically connected to the positive electrode or the negative electrode, the ratio of the discharge capacity of the battery to the initial discharge capacity [i.e., the battery's state of health (SOH)] is less than 1, optionally 0.7 to 0.9, which indicates that the battery has undergone capacity decay. At this time, there is a phenomenon of active lithium loss in the positive electrode or the negative electrode. In the case of full discharge / full charge, there are lattice vacancies in the positive electrode / negative electrode caused by lithium loss. In this case, the lithium-supplementing electrode is electrically connected to the positive electrode or the negative electrode, and the lithium-supplementing electrode can provide lithium ions to fill these lattice vacancies, thereby recovering the capacity loss of the battery due to the loss of active lithium and extending the cycle life of the battery.

[0132]

Electrical devices

[0133] An embodiment of the present application further provides an electrical device, which includes the above-mentioned battery.

[0134] The battery disclosed in the embodiments of the present application can be used in electrical devices that use batteries as power sources, or in various energy storage systems that use batteries as energy storage elements, to provide electrical energy. The above-mentioned battery contains a lithium-supplementing electrode with a special structure. After the battery capacity has decayed to a certain extent, the lithium-supplementing electrode can be electrically connected to the positive electrode or the negative electrode, which is conducive to recovering the capacity loss of the battery due to the loss of active lithium and extending the cycle life of the battery. Therefore, using the above-mentioned battery to provide electrical energy for various electrical devices helps to extend the service life of the electrical devices.

[0135] Electrical devices may include, but are not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, and the like. Electric toys may include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys. Spacecraft may include airplanes, rockets, space shuttles, and spacecraft. For these electrical devices, battery cells, battery modules, or battery packs may be selected based on their intended use.

[0136] Figure 8 shows an example of an electric device. This device can be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the battery, a battery pack or battery module can be used.

[0137] The following describes the details in conjunction with specific embodiments.

[0138] Example 1

[0139] This embodiment provides a battery, specifically a battery cell, and also provides lithium replenishment to the battery through a certain method after the battery capacity decays to a certain extent.

[0140] Specifically, the battery of this embodiment includes a positive electrode, a negative electrode, a lithium supplement electrode, a separator and an electrolyte, wherein the lithium supplement electrode includes a metal lithium sheet (10mm*50mm*50μm, mass 13.35mg, capacity 51.53mAh), and both surfaces of the metal lithium sheet are coated with a protective layer with a thickness of L=5μm, and the protective layer contains a pomegranate-type solid electrolyte Li with a mass content of 95%. 6.5 La3Zr2Ta 0.5 O 12 (LLZTO), the ionic conductivity σ of the protective layer is 0.47 mS / cm (25°C).

[0141] The positive electrode, separator and negative electrode are stacked and wound in sequence to form a battery cell, and the electrolyte is injected into the battery cell; at the same time, the lithium supplement electrode is in contact with the electrolyte and isolated from the positive electrode and negative electrode by the separator.

[0142] The battery of this embodiment is prepared and assembled by the following steps:

[0143] 1) Preparation of positive electrode

[0144] 1 kg of the positive electrode active material (LiNi5Co2Mn3O2), 20 g of the conductive agent (carbon nanotubes), and 20 g of the binder (polyvinylidene fluoride, PVDF) were weighed and added to 1 kg of N-methylpyrrolidone. The mixture was stirred in a blender for 30 minutes to form a stable, uniform slurry. This slurry was evenly coated on the surface of the current collector aluminum foil and dried in an oven at 80°C to form an active material layer. The active material layer was then rolled at a pressure of 2 MPa to produce a battery positive electrode sheet. The tabs were then spot-welded to form the battery positive electrode.

[0145] 2) Preparation of negative electrode

[0146] Weigh 1 kg of negative electrode active material (artificial graphite negative electrode material with a particle size of 15 μm), 10 g of conductive agent (acetylene black), and binder (30 g of styrene-butadiene rubber, 20 g of sodium carboxymethyl cellulose) and add them to 1 kg of deionized water. After stirring, coating, drying, rolling, and spot welding the electrode ears, the battery negative electrode is obtained.

[0147] 3) Preparation of lithium-supplementing electrodes

[0148] Pomegranate-type solid electrolyte Li 6.5 La3Zr2Ta 0.5 O 12 (LLZTO) and polytetrafluoroethylene (PTFE) are heated and mixed in a mass ratio of 95:5, and then extruded onto the surface of a metal lithium sheet to form a protective layer with a thickness of L = 5 μm; a nickel tab is welded to one section of the metal lithium sheet to produce a lithium supplement electrode.

[0149] 4) Electrolyte configuration

[0150] The electrolyte composition includes 1 mol / L lithium hexafluorophosphate and the solvent is EC:DMC:DEC in a volume ratio of 1:1:1.

[0151] 5) Battery assembly

[0152] The positive electrode, negative electrode and polyolefin microporous membrane prepared above are wound into a battery cell, the lithium supplement electrode is set on the outermost layer of the battery cell, and the lithium supplement electrode is separated from the positive electrode and negative electrode in the battery cell by a separator, and the electrolyte is injected and packaged to obtain a battery.

[0153] After assembly, the battery is subjected to formation and charge-discharge tests. After the battery capacity decays to a certain extent, the battery is replenished with lithium. The specific operations are as follows:

[0154] (1) Battery formation

[0155] The formation method is as follows: Using a blue-electric test system, the positive and negative electrodes are electrically connected, left to stand for 1 minute, and then charged at a constant current of 8mA to 4.2V. Then, constant voltage charging is performed at 4.2V with a cutoff current of 2mA. After standing for 10 minutes, the battery is discharged at a constant current of 8mA to a cutoff voltage of 2.5V, and left to stand for 50 hours. After formation, the SEI film forms and reduces the polarization of the battery.

[0156] (2) Battery test: The test steps are as follows: 60mA constant current charging, cut-off voltage is 4.2V; 4.2V constant voltage charging, cut-off current is 8mA; after standing for 10 minutes, 60mA constant current discharge, cut-off voltage is 2.5V.

[0157] After the charge and discharge tests, the battery's first-cycle charge capacity and first-cycle discharge capacity (D1) are obtained. The first-cycle charge capacity refers to the capacity of the battery cell after the first test, which is first charged at a constant current of 60mA to 4.2V, and then charged at a constant voltage of 4.2V to a cutoff current of 8mA. The first-cycle discharge capacity (D1) refers to the capacity discharged by the battery cell when discharged at a constant current of 60mA to a voltage of 2.5V.

[0158] Repeat the battery test steps to test the battery's cycling performance. Stop the test when the battery's discharge capacity decays to 0.8D1 and record the number of cycles x1.

[0159] (3) Lithium supplementation

[0160] The battery whose capacity has decayed to 80% in step (2) is subjected to positive electrode lithium replenishment, specifically:

[0161] Use the Blue Electric test system, discharge to the lower limit voltage (2.5V) with a current of 0.33C, then stand for 30 minutes, then continue to discharge to the lower limit voltage with a current of 0.04C, after standing for 30 minutes, discharge to the lower limit voltage with a current of 0.04C, and after three discharges at 0.04C, the battery SOC is considered to be adjusted to 0. Disconnect the electrical connection between the positive and negative electrodes, and electrically connect the positive electrode and the lithium replenishment electrode, and then follow the steps below: stand for 10 minutes, discharge at a constant current to 2.5V at a current of I and stand for 10 minutes to complete the lithium replenishment. Where I = 1mA; the current density on the surface of the lithium replenishment electrode is J = I / S = 0.1mA·cm -2 , S is the surface area of ​​the lithium-supplementing electrode, S = 10 cm 2 .

[0162] The battery after lithium replenishment is subjected to charge and discharge tests. The charge and discharge test steps are carried out according to the battery test process in step (2). The battery after lithium replenishment is cycled until the discharge capacity decays to 0.8D1, and the test is stopped and the number of cycles X2 is recorded.

[0163] Example 2

[0164] The difference between this embodiment and embodiment 1 is that the thickness of the protective layer L is 2 μm. Other aspects are the same as those of embodiment 1.

[0165] Example 3

[0166] The difference between this embodiment and embodiment 1 is that the thickness of the protective layer L is 20 μm. Other aspects are the same as those of embodiment 1.

[0167] Example 4

[0168] The difference between this embodiment and embodiment 1 is that the thickness of the protective layer L is 1 μm. Other aspects are the same as those of embodiment 1.

[0169] Example 5

[0170] The difference between this embodiment and embodiment 1 is that the thickness of the protective layer L is 30 μm. Other aspects are the same as those of embodiment 1.

[0171] Example 6

[0172] The difference between this embodiment and embodiment 1 is that the pomegranate type solid electrolyte LLZTO is replaced by the NASICON type solid electrolyte Li 1.5 Al 0.5 Ge 1.5 (PO4)3(LAGP) Other contents are the same as those in Example 1.

[0173] Example 7

[0174] The difference between this embodiment and embodiment 1 is that: J = 0.05 mA·cm-2 , I = 0.5 mA. Other parameters are the same as those in Example 1.

[0175] Example 8

[0176] The difference between this embodiment and embodiment 1 is that: J = 0.2 mA·cm -2 , I = 2 mA. Other parameters are the same as those in Example 1.

[0177] Example 9

[0178] The difference between this embodiment and embodiment 1 is that: J = 0.5 mA cm -2 , I = 5 mA. Other parameters are the same as those in Example 1.

[0179] Example 10

[0180] The difference between this embodiment and embodiment 1 is that: J = 1 mA·cm -2 , I=10mA cm -2 The rest are the same as in Example 1.

[0181] Example 11

[0182] The difference between this embodiment and embodiment 1 is that: J = 5mA·cm -2 , I = 50 mA. Other parameters are the same as those in Example 1.

[0183] Example 12

[0184] The difference between this embodiment and embodiment 1 is that the ionic conductivity σ of the protective layer of the lithium-supplemented electrode is 0.16 mS / cm (25° C.; the ionic conductivity of the protective layer is reduced by reducing the LLZTO content in the protective layer to 10%). Other aspects are the same as those of embodiment 1.

[0185] Example 13

[0186] The difference between this embodiment and embodiment 1 is that the ionic conductivity σ of the protective layer of the lithium-supplemented electrode is 0.05 mS / cm (25° C.; the ionic conductivity of the protective layer is reduced by reducing the LLZTO content in the protective layer to 5%). Other aspects are the same as those of embodiment 1.

[0187] Comparative Example 1

[0188] The difference between this comparative example and Example 1 is that the lithium supplement electrode does not contain a protective layer, that is, the lithium supplement electrode is made by welding a metal lithium sheet without a solid electrolyte protective layer to a nickel tab.

[0189] The test results of X1, X2, etc. obtained in the embodiments and comparative examples are shown in the following table.

[0190] Table 1. Performance test results

[0191] The test results reflect:

[0192] In a battery using a single lithium metal sheet as the lithium replenishment electrode (Comparative Example 1), the battery's discharge capacity decayed to 0.8 D1 after 737 charge-discharge cycles (X1). However, in Examples 1-13, by adding a protective layer containing a solid electrolyte with excellent ionic conductivity to the surface of the lithium metal sheet in the lithium replenishment electrode, the number of cycles (X1) required for the discharge capacity to decay to 0.8 D1 was significantly increased, reaching over 745 cycles.

[0193] Furthermore, after the battery capacity decays, Examples 1-9 electrically connect the lithium-replenishing electrode to the positive electrode, extending the total number of cycles until the battery capacity decays to 0.8D1 to 1064-1260 cycles, significantly improving the cycle life (an increase of 9.35%-29.50% compared to 973 cycles in Comparative Example 1). Furthermore, the cycle life extension effect can be further optimized by adjusting the ionic conductivity σ of the protective layer, the thickness L of the protective layer, and the discharge current during the lithium-replenishing process.

[0194] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A battery, characterized in that: The battery comprises a positive electrode, a negative electrode and a lithium supplement electrode, wherein the lithium supplement electrode is isolated from the positive electrode and the negative electrode; the lithium supplement electrode comprises a lithium supplement matrix and a protective layer covering the lithium supplement matrix; wherein the lithium supplement matrix contains a lithium supplement agent, and the protective layer has ionic conductivity.

2. The battery according to claim 1, characterized in that: The thickness of the protective layer is 1 to 30 μm.

3. The battery according to claim 2, characterized in that: The thickness of the protective layer is 2-20 μm.

4. The battery according to any one of claims 1 to 3, characterized in that: The ionic conductivity of the protective layer at 25° C. is 0.05 to 20 mS / cm.

5. The battery according to claim 4, characterized in that: The ionic conductivity of the protective layer at 25° C. is 0.47 to 0.72 mS / cm.

6. The battery according to claim 1, characterized in that: The protective layer includes a solid electrolyte.

7. The battery according to claim 6, characterized in that: The mass content of the solid electrolyte in the protective layer is greater than 10%.

8. The battery according to claim 7, characterized in that: The mass content of the solid electrolyte in the protective layer is 50-100%.

9. The battery according to any one of claims 6 to 8, characterized in that: The solid electrolyte includes one or more of an inorganic solid electrolyte, a polymer solid electrolyte, and an inorganic-polymer composite solid electrolyte.

10. The battery according to claim 9, characterized in that: The inorganic solid electrolyte includes one or more of lithium nitride, lithium oxynitride, lithium fluoride, lithium chloride, lithium phosphide, lithium oxide, lithium phosphate, lithium carbonate, nitrogen-containing lithium phosphate, garnet-type solid electrolyte, NASICON-type solid electrolyte, perovskite-type solid electrolyte, and antiperovskite-type solid electrolyte.

11. The battery according to claim 9, characterized in that: The polymer solid electrolyte includes one or more of polyethylene, polypropylene, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, polyimide, polydimethylsiloxane, polymethyl methacrylate, lithiated acrylic acid, and lithiated perfluorosulfonic acid resin.

12. The battery according to claim 1, characterized in that: The ratio between the capacity of the lithium supplement and the initial discharge capacity of the battery is 0.05 to 0.

2.

13. The battery according to claim 12, characterized in that: The ratio between the capacity of the lithium supplement and the initial discharge capacity of the battery is 0.1 to 0.

2.

14. The battery according to claim 12 or 13, characterized in that: The positive electrode includes a positive electrode active material, the negative electrode includes a negative electrode active material, and the lithium supplement has a potential lower than at least one of the positive electrode active material and the negative electrode active material.

15. The battery according to claim 14, characterized in that: The lithium supplement includes one or more of lithium, lithium alloy, and lithium-rich metal oxide.

16. The battery according to claim 15, characterized in that: The lithium alloy includes an alloy composed of lithium and one or more of group IIA elements, group IB to group VIIIB elements, group IIIA elements, and group IVA elements.

17. A method for replenishing lithium in a battery, characterized in that: The battery comprises a positive electrode, a negative electrode and a lithium supplement electrode, wherein the lithium supplement electrode is isolated from the positive electrode and the negative electrode; the lithium supplement electrode comprises a lithium supplement matrix and a protective layer covering the lithium supplement matrix; wherein the lithium supplement matrix contains a lithium supplement agent, and the protective layer has ionic conductivity; The battery lithium replenishment method comprises: electrically connecting the lithium replenishment electrode to the positive electrode or the negative electrode.

18. The battery lithium replenishment method according to claim 17, characterized in that: After the lithium supplement electrode is electrically connected to the positive electrode or the negative electrode, the discharge current density through the surface of the lithium supplement electrode is greater than 0 and less than or equal to 5 mA·cm -2 .

19. The battery lithium replenishment method according to claim 18, characterized in that: After the lithium supplement electrode is electrically connected to the positive electrode or the negative electrode, the discharge current density through the surface of the lithium supplement electrode is 0.05 to 0.5 mA·cm -2 .

20. The battery lithium replenishment method according to any one of claims 17 to 19, characterized in that: Before the lithium supplement electrode is electrically connected to the positive electrode, the step of adjusting the state of charge of the battery to 0-3% is included.

21. The battery lithium replenishment method according to claim 20, characterized in that: Before the lithium supplement electrode is electrically connected to the positive electrode, the step of adjusting the state of charge of the battery to 0-1% is included.

22. The method for replenishing lithium in a battery according to any one of claims 17 to 19, characterized in that: Before the lithium supplement electrode is electrically connected to the negative electrode, the step of adjusting the state of charge of the battery to 97% to 100% is included.

23. The battery lithium replenishment method according to claim 22, characterized in that: Before the lithium supplement electrode is electrically connected to the negative electrode, the step of adjusting the state of charge of the battery to 99% to 100% is included.

24. The method for replenishing lithium in a battery according to any one of claims 17 to 19, characterized in that: Before the lithium supplement electrode is electrically connected to the positive electrode or the negative electrode, the ratio of the discharge capacity of the battery to the initial discharge capacity is less than 1.

25. The battery lithium replenishment method according to claim 24, characterized in that: Before the lithium supplement electrode is electrically connected to the positive electrode or the negative electrode, the ratio of the discharge capacity of the battery to the initial discharge capacity is 0.7 to 0.

9.

26. An electrical device, characterized in that: The electrical device comprises the battery according to any one of claims 1 to 16.

Images