Positive electrode sheet, preparation method therefor, battery and electrical device

Abstract

A positive electrode sheet, a preparation method therefor, a battery and an electrical device. The positive electrode sheet comprises a positive electrode active material layer; and a capacity compensation layer, the capacity compensation layer being arranged on a side of the positive electrode active material layer, the capacity compensation layer comprising a catalyst and a capacity compensator, and the average particle size of the capacity compensator being less than or equal to 2 μm. Thus, the present application increases the probability that the catalyst is in contact with the capacity compensator, reduces the decomposition potential of the capacity compensator, increases the capacity retention rate of a battery, and prolongs the service life of the battery.

Description

Positive electrode sheet and preparation method thereof, battery, and electrical equipment Technical Field

[0001] The present application relates to the field of batteries, and in particular to positive electrode sheets and methods for preparing the same, as well as batteries and electrical equipment. Background Art

[0002] Batteries are not only used in energy storage systems such as hydropower, thermal, wind, and solar power plants, but are also widely used in electric vehicles such as electric bicycles, electric motorcycles, and electric vehicles, as well as in a variety of fields such as military equipment and aerospace. During the battery formation process, a solid electrolyte membrane (SEI membrane) is formed. This formation of the SEI membrane consumes active metal ions. To compensate for the irreversible capacity loss caused by the formation of the SEI membrane, the battery includes a capacity compensator. However, the decomposition potential of the capacity compensator is generally high. Simply increasing the voltage to improve the decomposition efficiency of the capacity compensator will deteriorate the electrolyte, thereby reducing the battery's capacity retention rate.

[0003] Summary of the Invention

[0004] In view of the technical problems existing in the background technology, the present application provides a positive electrode plate, aiming to improve the capacity retention rate of the battery containing the positive electrode plate.

[0005] The first aspect of the present application provides a positive electrode plate, comprising a positive electrode active material layer, wherein the positive electrode active material layer comprises a positive electrode active material; a capacity compensation layer, wherein the capacity compensation layer is arranged on one side of the positive electrode active material layer, the capacity compensation layer comprises a catalyst and a capacity compensator, and the average particle size of the capacity compensator is less than or equal to 2 μm.

[0006] The positive electrode plate proposed in the present application includes a positive electrode active material layer and a capacity compensation layer, and the capacity compensation layer includes a catalyst and a capacity compensator. By adding a catalyst to the capacity compensation layer, the catalyst can reduce the decomposition activation energy of the capacity compensator, making it easier for the active metal ions of the capacity compensator to be released, thereby reducing the decomposition potential of the capacity compensator. In addition, by controlling the average particle size of the capacity compensator to be less than or equal to 2 μm, the present application can increase the probability of contact between the catalyst and the capacity compensator, increase the reaction sites of the capacity compensator, and improve the transmission capacity of ions and electrons, which is conducive to further reducing the decomposition potential of the capacity compensator, thereby improving the decomposition efficiency and utilization rate of the capacity compensator, and thereby improving the capacity retention rate of the battery and improving the life of the battery.

[0007] According to some embodiments of the present application, the average particle size of the capacity compensating agent is 50 nm-2 μm.

[0008] According to some embodiments of the present application, the average particle size of the capacity compensating agent is 50nm-500nm.

[0009] Therefore, by making the average particle size of the capacity compensating agent within the above range, the probability of contact between the catalyst and the capacity compensating agent can be further increased, the reaction sites of the capacity compensating agent can be increased, the capacity compensating agent's ability to transmit ions and electrons can be improved, the decomposition potential of the capacity compensating agent can be further reduced, the decomposition efficiency and utilization rate of the capacity compensating agent can be improved, and the capacity retention rate of the battery can be improved, thereby increasing the battery life.

[0010] According to some embodiments of the present application, the average particle size of the catalyst is less than or equal to the average particle size of the capacity compensating agent. This increases the probability of contact between the catalyst and the capacity compensating agent, increases the reaction sites of the capacity compensating agent, improves the capacity compensating agent's ability to transport ions and electrons, further reduces the decomposition potential of the capacity compensating agent, and improves the decomposition efficiency and utilization rate of the capacity compensating agent, thereby improving the battery's capacity retention rate and extending the battery life.

[0011] According to some embodiments of the present application, the average particle size of the catalyst is 50 nm-2 μm.

[0012] According to some embodiments of the present application, the average particle size of the catalyst is 50 nm-500 nm.

[0013] Therefore, by setting the average particle size of the catalyst within the above range, the probability of contact between the catalyst and the capacity compensating agent can be further increased, the active ions of the capacity compensating agent can be more easily released, and the decomposition potential of the capacity compensating agent can be reduced.

[0014] According to some embodiments of the present application, the BET specific surface area of ​​the catalyst is 87 m 2 / g-200m 2 Therefore, by setting the BET specific surface area of ​​the catalyst within the above range, the probability of contact between the catalyst and the capacity compensating agent can be increased, the active ions of the capacity compensating agent can be more easily released, and the decomposition potential of the capacity compensating agent can be reduced.

[0015] According to some embodiments of the present application, the BET specific surface area of ​​the catalyst is 130 m 2 / g-200m 2 / g.

[0016] According to some embodiments of the present application, based on the total mass of the capacity compensation layer, the ratio of the mass of the catalyst to the mass of the capacity compensating agent is (5-40): 100. This reduces the decomposition potential of the capacity compensating agent and improves the efficiency of capacity compensation.

[0017] According to some embodiments of the present application, based on the total mass of the positive electrode sheet, the ratio of the mass of the capacity compensating agent to the mass of the positive electrode active material is (0.5-20): 100. This improves the efficiency of capacity compensation.

[0018] According to some embodiments of the present application, the catalyst includes a metal compound, thereby making it easier for the active metal ions of the capacity compensator to be released, thereby reducing the decomposition potential of the capacity compensator.

[0019] According to some embodiments of the present application, at least a portion of the surface of the metal compound has a carbon coating layer. Thus, the carbon coating layer can improve the electronic conductivity of the catalyst, further reduce the decomposition potential of the capacity compensator, and improve the efficiency of capacity compensation.

[0020] According to some embodiments of the present application, the carbon coating layer accounts for 5% to 30% of the total mass of the metal compound and the carbon coating layer, thereby improving the electronic conductivity of the catalyst and further promoting the release of active metal ions in the capacity compensator.

[0021] According to some embodiments of the present application, the metal compound includes at least one of a transition metal oxide, a transition metal carbide, a transition metal nitride, a transition metal sulfide, or a transition metal phosphide.

[0022] According to some embodiments of the present application, the capacity compensator includes a lithium supplement and / or a sodium supplement, and the lithium supplement includes at least one of Li2O, Li2O2, Li2CO3, Li2C2O4, Li2C4O4, Li2S, Li2Se, Li2Se2 or LiF; the sodium supplement includes at least one of Na2O, Na2O2, Na2CO3, Na2C2O4, Na2C4O4, Na2S, Na2Se, Na2Se2 or NaF.

[0023] According to some embodiments of the present application, the positive electrode sheet further includes a positive electrode current collector, the positive electrode active material layer is located on one side of the positive electrode current collector, and the capacity compensation layer is located on a side of the positive electrode active material layer away from the positive electrode current collector. This improves the efficiency of capacity compensation and the structural stability of the positive electrode sheet.

[0024] The second aspect of the present application provides a method for preparing a positive electrode plate, comprising: forming a positive electrode active material layer, wherein the positive electrode active material layer includes a positive electrode active material; forming a capacity compensation layer on one side of the positive electrode active material layer, wherein the capacity compensation layer includes a catalyst and a capacity compensator, and the average particle size of the capacity compensator is less than or equal to 2 μm.

[0025] Thus, the positive electrode sheet prepared by the method proposed in this application includes both a catalyst and a capacity compensator. The catalyst can reduce the decomposition activation energy of the capacity compensator, making it easier for the active ions of the capacity compensator to escape, and reducing the decomposition potential of the capacity compensator. Furthermore, by setting the average particle size of the capacity compensator within the above range, the probability of contact between the catalyst and the capacity compensator can be increased, increasing the reaction sites of the capacity compensator and improving the ion and electron transport capacity, further reducing the decomposition potential of the capacity compensator, and improving the decomposition efficiency and utilization rate of the capacity compensator, thereby improving the capacity retention rate of the battery and extending the battery life.

[0026] According to some embodiments of the present application, the method for forming the capacity compensation layer further includes: forming a catalyst layer on one side of the positive electrode active material layer, and forming the capacity compensator within the catalyst layer by electrochemical deposition. Thus, electrochemical deposition can in situ form a capacity compensator with a smaller average particle size on the catalyst, thereby increasing the probability of contact between the catalyst and the capacity compensator, increasing the reaction sites of the capacity compensator, improving the transport capacity for ions and electrons, further reducing the decomposition potential of the capacity compensator, and improving the decomposition efficiency and utilization rate of the capacity compensator, thereby improving the capacity retention rate of the battery and extending the battery life.

[0027] According to some embodiments of the present application, the porosity of the catalyst layer is 30%-70%, thereby improving the efficiency of in-situ deposition of the capacity compensator on the catalyst surface during the electrochemical deposition process.

[0028] According to some embodiments of the present application, the porosity of the catalyst layer is 30%-50%, thereby improving the efficiency of in-situ deposition of the capacity compensator on the catalyst surface during the electrochemical deposition process.

[0029] The third aspect of the present application provides a battery, comprising the positive electrode sheet provided in the first aspect of the present application or the positive electrode sheet prepared by the method provided in the second aspect of the present application, thereby improving the capacity retention rate of the battery.

[0030] A fourth aspect of the present application provides an electrical device, comprising the battery provided in the third aspect of the present application, thereby increasing the life of the electrical device.

[0031] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become obvious from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0033] FIG1 is a schematic structural diagram of a positive electrode sheet according to an embodiment of the present application.

[0034] FIG2 is a SEM image of a catalyst and a capacity compensating agent according to one embodiment of the present application.

[0035] FIG3 is a schematic structural diagram of a positive electrode sheet according to another embodiment of the present application.

[0036] FIG4 is a schematic diagram of a battery according to an embodiment of the present application.

[0037] FIG. 5 is an exploded view of the battery shown in FIG. 4 according to an embodiment of the present application.

[0038] FIG6 is a schematic diagram of a battery module according to an embodiment of the present application.

[0039] FIG7 is a schematic diagram of a battery pack according to an embodiment of the present application.

[0040] FIG8 is an exploded view of the battery pack shown in FIG7 according to an embodiment of the present application.

[0041] FIG9 is a schematic diagram of an electrical device using a battery as a power source according to an embodiment of the present application.

[0042] Explanation of reference numerals: 1 battery pack; 2 upper case; 3 lower case; 4 battery module; 5 secondary battery; 51 housing; 52 electrode assembly; 53 cover plate; 521 positive electrode sheet; 5211 positive electrode active material layer; 5212 capacity compensation layer; 5213 positive electrode current collector. DETAILED DESCRIPTION

[0043] The following embodiments of the technical solution of the present application are described in detail. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only used as examples and are not intended to limit the scope of protection of the present application.

[0044] 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.

[0045] For the sake of clarity, only some numerical ranges are specifically disclosed herein. However, any lower limit may be combined with any upper limit to form an unspecified range; and any lower limit may be combined with other lower limits to form an unspecified range, and similarly, any upper limit may be combined with any other upper limit to form an unspecified range. In addition, each individually disclosed point or single value may itself serve as a lower limit or upper limit and be combined with any other point or single value, or with other lower limits or upper limits, to form an unspecified range.

[0046] 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.

[0047] 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.

[0048] Currently, market developments indicate that batteries are increasingly being used. They are not only used in energy storage systems such as hydropower, thermal, wind, and solar power plants, but are also widely used in electric vehicles like electric bicycles, electric motorcycles, and electric cars, as well as in military equipment and aerospace. As battery applications continue to expand, market demand is also growing.

[0049] During the battery formation process, a SEI film will form on the surface of the negative electrode. During the formation of the SEI film, a large amount of active metal ions will be consumed, reducing the initial efficiency of the battery. In order to improve the initial efficiency of the battery, the negative or positive electrode can be pre-capacitated. When performing capacity compensation on the positive electrode, additives rich in active metal ions are usually used to establish a capacity compensation layer on the positive electrode sheet. During the first cycle of charge and discharge, sufficient active metal ions are released to compensate for the irreversible capacity loss caused by the formation of the SEI film. However, the decomposition potential of the capacity compensator is relatively high. Simply increasing the voltage will deteriorate the electrolyte, thus limiting the capacity compensation effect of the capacity compensator.

[0050] The present application proposes a positive electrode plate, which includes a positive electrode active material layer and a capacity compensation layer, wherein the capacity compensation layer includes a catalyst and a capacity compensator. By adding a catalyst to the capacity compensation layer, the decomposition potential of the capacity compensator can be reduced, and by reducing the average particle size of the capacity compensator, the probability of contact between the capacity compensator and the catalyst can be increased, the reaction sites of the capacity compensator are increased, and the transmission capacity of ions and electrons is improved, which is conducive to further reducing the decomposition potential of the capacity compensator, improving the decomposition efficiency and utilization rate of the capacity compensator, and thereby improving the capacity retention rate of the battery and increasing the battery life.

[0051] The positive electrode sheet disclosed in the embodiment of the present application is suitable for lithium-ion batteries and sodium-ion batteries, and the battery disclosed in the embodiment of the present application can be used in electrical equipment that uses batteries as power sources or various energy storage systems that use batteries as energy storage elements. Electrical equipment may include but is not limited to mobile phones, tablets, laptops, electric toys, power tools, battery cars, electric cars, ships, spacecraft, etc. Among them, electric toys may include fixed or mobile electric toys, for example, game consoles, electric car toys, electric ship toys and electric airplane toys, etc., and spacecraft may include airplanes, rockets, space shuttles and spacecraft, etc.

[0052] In a first aspect, the present application provides a positive electrode plate 521. Referring to Figure 1, the positive electrode plate 521 includes a positive electrode active material layer 5211, wherein the positive electrode active material layer 5211 includes a positive electrode active material; a capacity compensation layer 5212, wherein the capacity compensation layer 5212 is arranged on one side of the positive electrode active material layer 5211, and the capacity compensation layer 5212 includes a catalyst and a capacity compensator, and the average particle size of the capacity compensator is less than or equal to 2μm.

[0053] The positive electrode plate 521 proposed in this application includes a positive electrode active material layer 5211 and a capacity compensation layer 5212. The capacity compensation layer 5212 includes a catalyst and a capacity compensator. By adding a catalyst to the capacity compensation layer 5212, the catalyst can reduce the decomposition activation energy of the capacity compensator, making it easier for the active metal ions of the capacity compensator to be released, thereby reducing the decomposition potential of the capacity compensator. In addition, by controlling the average particle size of the capacity compensator to be less than or equal to 2μm, the present application can increase the probability of contact between the catalyst and the capacity compensator, increase the reaction sites of the capacity compensator, and improve the transmission capacity for ions and electrons, which is conducive to further reducing the decomposition potential of the capacity compensator, thereby improving the decomposition efficiency and utilization rate of the capacity compensator, and thus improving the capacity retention rate of the battery and extending the battery life. When the particle size of the capacity compensator is greater than 2μm, due to the excessively large average particle size of the capacity compensator, the contact efficiency between the capacity compensator and the catalyst is reduced, which will reduce the catalytic effect of the catalyst.

[0054] According to some embodiments of the present application, the average particle size of the capacity compensating agent may be 20 nm, 40 nm, 50 nm, 100 nm, 500 nm, 1 μm, 1.5 μm or 2 μm, or may be a range consisting of any of the above values. According to some specific embodiments of the present application, the average particle size of the capacity compensating agent may be 50 nm-2 μm. According to other specific embodiments of the present application, the average particle size of the capacity compensating agent may be 50 nm-500 nm.

[0055] According to some embodiments of the present application, the average particle size of the catalyst is less than or equal to the average particle size of the capacity compensating agent. This increases the probability of contact between the catalyst and the capacity compensating agent, increases the reaction sites of the capacity compensating agent, improves the capacity compensating agent's ability to transport ions and electrons, further reduces the decomposition potential of the capacity compensating agent, and improves the decomposition efficiency and utilization rate of the capacity compensating agent, thereby improving the battery's capacity retention rate and extending the battery life.

[0056] According to some embodiments of the present application, the average particle size of the catalyst is 50 nm-2 μm, for example, 50 nm, 100 nm, 500 nm, 1 μm, 1.5 μm, or 2 μm, or a range consisting of any of the above values. According to other specific embodiments of the present application, the average particle size of the catalyst can be 50 nm-500 nm.

[0057] In this application, the capacity compensator and the catalyst can be distinguished by a FEI Talos FS200x transmission electron microscope combined with an X-ray energy dispersive spectrometer (EDS). Specifically, 0.01 g of the capacity compensation layer powder is placed in a transmission electron microscope, and the magnification is adjusted to observe the sample to ensure that the sample is clear and the quantity is distinguishable. By EDS elemental analysis, the capacity compensator and the catalyst can be distinguished by specific metal elements in the catalyst. The particle size of the capacity compensator and the catalyst particles is counted separately (not less than 10 particles), and the average value is taken to obtain the average particle size of the capacity compensator and the catalyst particles.

[0058] According to some embodiments of the present application, referring to FIG2 , the capacity compensating agent is coated on at least a portion of the surface of the catalyst. This increases the probability of contact between the catalyst and the capacity compensating agent, increases the number of reaction sites for the capacity compensating agent, further reduces the decomposition potential of the capacity compensating agent, and improves the decomposition efficiency and utilization rate of the capacity compensating agent, thereby improving the battery's capacity retention rate and extending the battery life.

[0059] According to some embodiments of the present application, the capacity compensator may include a lithium supplement and / or a sodium supplement, the lithium supplement including at least one of Li2O, Li2O2, Li2CO3, Li2C2O4, Li2C4O4, Li2S, Li2Se, Li2Se2 or LiF; the sodium supplement including at least one of Na2O, Na2O2, Na2CO3, Na2C2O4, Na2C4O4, Na2S, Na2Se, Na2Se2 or NaF. Thus, when the battery is a lithium ion battery, the capacity compensating agent adopts a lithium supplement, such as at least one of Li2O, Li2O2, Li2CO3, Li2C2O4, Li2C4O4, Li2S, Li2Se, Li2Se2 or LiF, which can increase the probability of the lithium supplement contacting the catalyst, thereby increasing the reaction sites of the lithium supplement, further reducing the decomposition potential of the lithium supplement, improving the decomposition efficiency and utilization rate of the lithium supplement, thereby improving the capacity retention rate of the battery and improving the life of the battery; when the battery is a sodium ion battery, the capacity compensating agent adopts a sodium supplement, such as at least one of Na2O, Na2O2, Na2CO3, Na2C2O4, Na2C4O4, Na2S, Na2Se, Na2Se2 or NaF, which can increase the probability of the sodium supplement contacting the catalyst, thereby increasing the reaction sites of the sodium supplement, further reducing the decomposition potential of the sodium supplement, improving the decomposition efficiency and utilization rate of the sodium supplement, thereby improving the capacity retention rate of the battery and improving the life of the battery.

[0060] According to some embodiments of the present application, the BET specific surface area of ​​the catalyst can be 87 m 2 / g-200m 2 / g, for example, can be 87m 2 / g、100m 2 / g, 120m 2 / g, 140m 2 / g, 160m 2 / g, 180m 2 / g or 200m 2 / g, etc., or can be a range composed of any of the above values. Thus, the probability of contact between the catalyst and the capacity compensator is increased, the reaction sites of the capacity compensator are increased, the decomposition potential of the capacity compensator is further reduced, the decomposition efficiency and utilization rate of the capacity compensator are improved, and the capacity retention rate of the battery is improved, thereby increasing the life of the battery. According to some specific embodiments of the present application, the BET specific surface area of ​​the catalyst can be 130m 2 / g-200m 2 / g.

[0061] In this application, the thermal decomposition temperature of the catalyst is about 1000°C-2000°C, and the thermal decomposition temperature of the capacity compensator is about 300°C-600°C. The capacity compensation layer on the positive electrode is scraped off and heated to 700°C-900°C under a nitrogen atmosphere. After the capacity compensator decomposes, the catalyst can be separated. The BET specific surface area can be measured by referring to the following method: Using the American Micrometer multi-station fully automatic specific surface area and pore analyzer GeminiVII2390, take about 7g of sample and place it in a 9cc long tube with a bulb, degas at 200°C for 2h, and then place it in the host to test to obtain the BET (specific surface area) data of the catalyst.

[0062] According to some embodiments of the present application, the catalyst may include a metal compound, thereby making it easier for the active metal ions of the capacity compensator to be released, thereby reducing the decomposition potential of the capacity compensator.

[0063] According to some embodiments of the present application, at least a portion of the surface of the metal compound has a carbon coating layer, thereby improving the electronic conductivity of the catalyst, further reducing the decomposition potential of the capacity compensator, and improving the efficiency of capacity compensation.

[0064] According to some embodiments of the present application, based on the total mass of the metal compound and the carbon coating layer, the mass proportion of the carbon coating layer is 5%-30%, for example, 5%, 10%, 15%, 20%, 25% or 30%, or a range consisting of any of the above values. This improves the electronic conductivity of the catalyst and further promotes the release of active metal ions in the capacity compensator.

[0065] In this application, the contents of the metal compound and the carbon coating can be measured using a TGA-601 thermogravimetric analyzer. A metal compound having a carbon coating on its surface is heated in an oxygen atmosphere in the thermogravimetric analyzer. The carbon material in the mixed material reacts with the oxygen to produce carbon dioxide. The carbon coating content M1 is obtained by weight loss, and the metal compound content is (100% - M1).

[0066] According to some embodiments of the present application, the metal compound includes at least one of a transition metal oxide, a transition metal carbide, a transition metal nitride, a transition metal sulfide, or a transition metal phosphide. As a result, the transition metal has an underfilled valence d orbital, which allows the electron cloud to deform easily and readily exchange electrons with the capacity compensator, thereby catalyzing the decomposition of the capacity compensator and allowing the capacity compensator to exert greater capacity at low potentials.

[0067] According to some embodiments of the present application, the capacity compensation layer includes a conductive agent, and the conductive agent includes at least one of superconducting carbon, Ketjen black, acetylene black, carbon nanotubes or graphene.

[0068] According to some embodiments of the present application, based on the total mass of the capacity compensation layer 5212, the ratio of the mass of the catalyst to the mass of the capacity compensating agent can be (5-40):100, for example, 5:100, 10:100, 15:100, 20:100, 25:100, 30:100, 35:100, or 40:100, or can be a range consisting of any of the above values. Thus, by making the ratio of the content of the catalyst to the content of the capacity compensating agent within the above range, the probability of contact between the catalyst and the capacity compensating agent is increased, the decomposition potential of the capacity compensating agent is reduced, the decomposition efficiency and utilization rate of the capacity compensating agent are increased, and thus the capacity retention rate of the battery is improved, thereby increasing the battery life.

[0069] According to some embodiments of the present application, based on the total mass of the capacity compensation layer 5212, the mass of the catalyst can be (0.002-0.024) g / 1540.25 mm 2 , for example, it can be 0.002g / 1540.25mm 2 、0.004g / 1540.25mm 2 、0.006g / 1540.25mm 2 、0.008g / 1540.25mm 2 、0.01g / 1540.25mm 2 、0.012g / 1540.25mm 2 、0.014g / 1540.25mm 2 、0.016g / 1540.25mm 2 、0.018g / 1540.25mm 2 、0.02g / 1540.25mm 2 、0.022g / 1540.25mm 2 or 0.024g / 1540.25mm 2 According to some specific embodiments of the present application, based on the total mass of the capacity compensation layer 5212, the mass of the catalyst can be (0.002-0.012) g / 1540.25 mm 2 Thus, the probability of contact between the catalyst and the capacity compensator is increased, the decomposition potential of the capacity compensator is reduced, the decomposition efficiency and utilization rate of the capacity compensator are improved, and the capacity retention rate of the battery is improved, thereby increasing the battery life.

[0070] It should be noted that the 0.002g / 1540.25mm referred to here 2 , which means that the mass of the catalyst contained in each 1540.25 square millimeter capacity compensation layer 5212 is 0.002 g.

[0071] According to some embodiments of the present application, based on the total mass of the capacity compensation layer 5212, the mass of the capacity compensation agent can be (0.002-0.06) g / 1540.25 mm 2 , for example, it can be 0.002g / 1540.25mm 2 、0.01g / 1540.25mm 2 、0.015g / 1540.25mm 2 、0.02g / 1540.25mm 2 、0.025g / 1540.25mm 2 、0.03g / 1540.25mm 2 、0.035g / 1540.25mm 2 、0.04g / 1540.25mm 2 、0.045g / 1540.25mm 2 , 0.05g / 1540.25mm 2 、0.055g / 1540.25mm 2 or 0.06g / 1540.25mm 2 According to some specific embodiments of the present application, based on the total mass of the capacity compensation layer 5212, the mass of the capacity compensation agent can be (0.004-0.045) g / 1540.25 mm 2 Thus, the efficiency of capacity compensation is improved, the initial efficiency of the battery is improved, and the capacity retention rate of the battery is improved.

[0072] It should be noted that the 0.002g / 1540.25mm referred to here 2 , which means that the mass of the capacity compensating agent contained in each 1540.25 square millimeter of the capacity compensation layer 5212 is 0.002 g.

[0073] In this application, the catalyst content can be measured using a TGA-601 thermogravimetric analyzer. The thermal decomposition temperature of the catalyst is approximately 1000°C-2000°C, and the thermal decomposition temperature of the capacity compensator is approximately 300°C-600°C. The capacity compensation layer on the positive electrode is scraped off and heated to 700°C-900°C in a TGA-601 thermogravimetric analyzer with nitrogen. After the capacity compensator decomposes, the catalyst can be separated. The capacity compensator content M2 is obtained by weight loss, and the catalyst content is (100%-M2).

[0074] According to some embodiments of the present application, based on the total mass of the positive electrode plate 521, the ratio of the mass of the capacity compensator to the mass of the positive electrode active material can be (0.5-20):100, for example, 0.5:100, 1:100, 3:100, 5:100, 7:100, 9:100, 11:100, 13:100, 15:100, 17:100, 19:100 or 20:100, etc., or can be a range composed of any of the above numerical values. Thus, by making the mass ratio of the capacity compensator to the positive electrode active material within the above range, the capacity supplement can not only make up for the active metal ions consumed in forming the SEI film, but also, during the battery cycle, the capacity supplement can also replenish the active metal ions, thereby improving the cycle capacity retention rate of the battery.

[0075] According to some embodiments of the present application, based on the total mass of the positive electrode active material layer 5211, the mass of the positive electrode active material in the positive electrode active material layer 5211 can be (0.2-0.4) g / 1540.25 mm 2 , for example, it can be 0.2g / 1540.25mm 2 , 0.25g / 1540.25mm 2 、0.3g / 1540.25mm 2 , 0.35g / 1540.25mm 2 or 0.4g / 1540.25mm 2 According to some specific embodiments of the present application, based on the total mass of the positive electrode active material layer 5211, the mass of the positive electrode active material in the positive electrode active material layer 5211 can be (0.25-0.35) g / 1540.25 mm 2 .

[0076] It should be noted that the 0.2g / 1540.25mm referred to here 2 , which means that the mass of the positive electrode active material contained in each 1540.25 square millimeters of the positive electrode active material layer 5211 is 0.2 g.

[0077] In this application, the mass of the positive electrode active material can be measured using a TGA-601 thermogravimetric analyzer. The capacity compensation layer and active material layer are scraped off the positive electrode sheet in sequence. The active material layer material is placed in a thermogravimetric analyzer, oxygen is introduced, and the temperature is raised to 400°C. The substances in the active material layer material other than the positive electrode active material are first decomposed. Their content, M3, is obtained by weight loss. The content of the positive electrode active material is (100% - M3).

[0078] According to some embodiments of the present application, the thickness ratio of the capacity compensation layer 5212 to the positive electrode active material layer 5211 can be (15-50):100, for example, it can be 15:100, 20:100, 25:100, 30:100, 35:100, 40:100, 45:100 or 50:100, or it can be a range composed of any of the above numerical values. Thus, while improving the efficiency of capacity compensation, the overall thickness of the electrode is reduced, thereby improving the energy density of the battery. According to some specific embodiments of the present application, the thickness ratio of the capacity compensation layer 5212 to the positive electrode active material layer 5211 can be (20-38):100.

[0079] The thickness test method in this application is as follows: the thickness of the positive electrode sheet 521 containing the positive electrode active material layer 5211 and the positive electrode current collector 5213 is measured using a Mitutoyo 0-25mm micrometer, and the thickness of the positive electrode active material layer 5211 is measured as a minus the thickness of the positive electrode current collector; the thickness of the positive electrode sheet 521 containing the positive electrode active material layer 5211, the capacity compensation layer 5212, and the positive electrode current collector 5213 is measured using a Mitutoyo 0-25mm micrometer, and the thickness of the capacity compensation layer 5212 is measured as b. Specifically, during the thickness test, 10 points on the positive electrode sheet 521 can be randomly selected for testing and the thickness can be recorded. The average of the 10 points is taken as the thickness data.

[0080] According to some embodiments of the present application, the thickness of the capacity compensation layer 5212 may be 25 μm to 50 μm, for example, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, or 50 μm, or may be a range consisting of any of the above values. According to some specific embodiments of the present application, the thickness of the capacity compensation layer 5212 may be 30 μm to 45 μm. This improves the efficiency of capacity compensation and improves the initial efficiency and capacity retention rate of the battery.

[0081] According to some embodiments of the present application, the thickness of the positive electrode active material layer 5211 may be 100 μm-170 μm, for example, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, or 170 μm, or may be within a range consisting of any of the foregoing values. According to some specific embodiments of the present application, the thickness of the positive electrode active material layer 5211 may be 120 μm-150 μm.

[0082] According to some embodiments of the present application, referring to FIG3 , the positive electrode plate 521 may further include a positive electrode current collector 5213, the positive electrode active material layer 5211 being located on one side of the positive electrode current collector 5213, and the capacity compensation layer 5212 being located on a side of the positive electrode active material layer 5211 away from the positive electrode current collector 5213. This reduces the probability of collapse of the positive electrode active material layer 5211 caused by the release of active ions from the capacity compensation agent, improves the structural stability of the positive electrode plate 521, and increases the service life of the battery.

[0083] According to some embodiments of the present application, the positive electrode current collector 5213 may be a metal foil or a composite positive electrode current collector. For example, aluminum foil may be used as the metal foil. The composite positive electrode current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite positive electrode current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0084] According to some embodiments of the present application, when the battery is a lithium-ion battery, the positive electrode active material may adopt the positive electrode active material for lithium-ion batteries known in the art. As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.8 Co 0.15 Al 0.05 O2) and its modified compounds. Examples of olivine-structured lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[0085] According to some embodiments of the present application, when the battery is a sodium ion battery, for example, when the battery is a sodium ion battery, as an example, the positive electrode active material may include but is not limited to at least one of a layered transition metal oxide, a polyanion compound, and a Prussian blue analogue.

[0086] Examples of the layered transition metal oxides include:

[0087] Na 1-x Cu h Fe k Mn l M 1 m O 2-y , where M 1 One or more of Li, Be, B, Mg, Al, K, Ca, Ti, Co, Ni, Zn, Ga, Sr, Y, Nb, Mo, In, Sn and Ba, 0 <x≤0.33,0<h≤0.24,0≤k≤0.32,0<l≤0.68,0≤m<0.1,h+k+l+m=1,0≤y<0.2;

[0088] Na 0.67 Mn 0.7 Ni z M 2 0.3-z O2, where M 2 is one or more of Li, Mg, Al, Ca, Ti, Fe, Cu, Zn and Ba, 0 <z≤0.1;

[0089] Na a Li b Ni c Mn d Fe eO2, where 0.67 < a ≤ 1, 0 < b < 0.2, 0 < c < 0.3, 0.67 < d + e < 0.8, and b + c + d + e = 1.

[0090] Examples of the above polyanionic compounds include, for example:

[0091] A 1 f M 3 g (PO4) i O j X 1 3-j , where A 1 is one or more of H, Li, Na, K, and NH4, M 3 is one or more of Ti, Cr, Mn, Fe, Co, Ni, V, Cu, and Zn, X 1 is one or more of F, Cl, and Br, 0 < f ≤ 4, 0 < g ≤ 2, 1 ≤ i ≤ 3, 0 ≤ j ≤ 2;

[0092] Na n M 4 PO4X 2 , where M 4 is one or more of Mn, Fe, Co, Ni, Cu, and Zn, X 2 is one or more of F, Cl, and Br, 0 < n ≤ 2;

[0093] Na p M 5 q (SO4)3, where M 5 is one or more of Mn, Fe, Co, Ni, Cu, and Zn, 0 < p ≤​​​​​​​​​​​​​​​​​​​​​​​​​​​​6 and M 7 Each independently represents one or more of transition metal cations, where 0 < u ≤ 2, 0 < v ≤ 1, 0 < w ≤ 1, and 0 < x < 6. For example, A is H + , Li + , Na + , K + , NH4 + , Rb + , Cs + , Fr + , Be 2+ , Mg 2+ , Ca 2+ , Sr 2+ , Ba 2+ and Ra 2+ One or more of them, and M 6 and M 7 Each independently represents a cation of one or more transition metal elements selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn, and W.

[0097] The modified compounds of the above materials can be doping modification and / or surface coating modification of the materials.

[0098] According to some embodiments of the present application, the positive electrode active material layer 5211 may further include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride - tetrafluoroethylene - propylene terpolymer, vinylidene fluoride - hexafluoropropylene - tetrafluoroethylene terpolymer, tetrafluoroethylene - hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0099] According to some embodiments of the present application, the positive electrode active material layer 5211 may further include a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. ​The second aspect of the present application provides a method for preparing a positive electrode plate 521, comprising: forming a positive electrode active material layer 5211; forming a capacity compensation layer 5212 on one side of the positive electrode active material layer 5211, wherein the capacity compensation layer 5212 includes a catalyst and a capacity compensator, and the average particle size of the capacity compensator is less than or equal to 2μm. Thus, the capacity compensation layer 5212 prepared by the method proposed in the present application includes both a catalyst and a capacity compensator, and the catalyst can reduce the decomposition activation energy of the capacity compensator, making it easier for the active ions of the capacity compensator to escape, thereby reducing the decomposition potential of the capacity compensator. By making the average particle size of the capacity compensator within the above range, the probability of contact between the catalyst and the capacity compensator can be increased, the reaction sites of the capacity compensator can be increased, the transmission capacity of ions and electrons can be improved, the decomposition potential of the capacity compensator can be further reduced, the decomposition efficiency and utilization rate of the capacity compensator can be improved, and the capacity retention rate of the battery can be improved, thereby increasing the life of the battery.

[0101] According to some embodiments of the present application, the method of forming the capacity compensation layer 5212 further includes: forming a catalyst layer on one side of the positive electrode active material layer 5211, and forming the capacity compensator in the catalyst layer by electrochemical deposition.

[0102] According to some embodiments of the present application, the catalyst layer may be formed by mixing a catalyst, a binder, a conductive agent, and a solvent to form a slurry, and then coating the slurry on the electrode to form the catalyst layer.

[0103] According to some embodiments of the present application, when the capacity compensator is Li2O or Li2O2, the Li / / O2 battery principle is utilized, with the electrode containing the positive electrode active material layer 5211 and the catalyst layer as the positive electrode, and lithium metal as the negative electrode assembled into an electrochemical cell. In an O2 atmosphere, Li2O or Li2O2 is formed by adjusting different lower limit voltages. Since the catalyst layer has pores, Li2O or Li2O2 can enter the pores to form the capacity compensator in situ in the catalyst layer.

[0104] According to some embodiments of the present application, when the capacity compensator is Li2CO3, Li2C2O4 or Li2C4O4, the Li / / CO2 battery principle is utilized, an electrode containing a positive electrode active material layer 5211 and a catalyst layer is used as the positive electrode, and lithium metal is used as the negative electrode to assemble an electrochemical cell. Under a CO2 atmosphere, different lower limit voltages are adjusted to form Li2CO3, Li2C2O4 or Li2C4O4. Due to the pores in the catalyst layer, Li2CO3, Li2C2O4 or Li2C4O4 can enter the pores to form the capacity compensator in situ in the catalyst layer.

[0105] According to some embodiments of the present application, when the capacity compensator is Li2S, the principle of Li / / S battery is utilized, with an electrode sheet containing a positive electrode active material layer 5211 and a catalyst layer serving as the positive electrode, sulfur nanoparticles are applied to the catalyst layer, and lithium is assembled as the negative electrode into an electrochemical cell, and Li2S is formed under an inert gas atmosphere. Since the catalyst layer has pores, Li2S can enter the pores to form a capacity compensator in situ in the catalyst layer.

[0106] According to some embodiments of the present application, when the capacity compensator is Li2Se or Li2Se2, the Li / / Se battery principle is utilized, with an electrode containing a positive electrode active material layer 5211 and a catalyst layer as the positive electrode, selenium nanoparticles are applied on the catalyst layer, and lithium metal is assembled as the negative electrode into an electrochemical cell. Under an inert gas atmosphere, Li2Se or Li2Se2 is formed by adjusting different lower limit voltages. Due to the pores in the catalyst layer, Li2Se or Li2Se2 can enter the pores to form a capacity compensator in situ in the catalyst layer.

[0107] According to some embodiments of the present application, when the capacity compensator is LiF, the principle of Li / / CF battery is utilized, with an electrode sheet containing a positive electrode active material layer 5211 and a catalyst layer as the positive electrode, CF nanoparticles are applied on the catalyst layer, and lithium metal is assembled as the negative electrode into an electrochemical cell, and LiF is formed under an inert gas atmosphere. Since the catalyst layer has pores, LiF can enter the pores to form a capacity compensator in situ in the catalyst layer.

[0108] Therefore, electrochemical deposition can form a capacity compensator with a smaller average particle size in situ on the catalyst, increase the probability of contact between the catalyst and the capacity compensator, increase the reaction sites of the capacity compensator, improve the transmission capacity of ions and electrons, further reduce the decomposition potential of the capacity compensator, improve the decomposition efficiency and utilization rate of the capacity compensator, and thus improve the capacity retention rate of the battery and increase the life of the battery.

[0109] According to some embodiments of the present application, when a capacity compensator is formed in situ on a catalyst by electrochemical deposition, capacity compensators with different particle sizes can be obtained by adjusting the current.

[0110] According to some embodiments of the present application, the porosity of the catalyst layer may be 30%-70%, for example, 30%, 40%, 50%, 60% or 70%, or a range consisting of any of the above values. Thus, the efficiency of in-situ deposition of the capacity compensator on the catalyst surface is improved during electrochemical deposition, the probability of contact between the catalyst and the capacity compensator is increased, the decomposition potential of the capacity compensator is reduced, and the decomposition efficiency and utilization rate of the capacity compensator are improved. According to some specific embodiments of the present application, the porosity of the catalyst layer may be 30%-50%.

[0111] In this application, the porosity of the catalyst layer is measured using a fully automatic gas replacement density meter AccuPyc II 1340. Ten positive electrode plates with the same thickness D and area S are placed in a density tester. Helium or nitrogen is introduced according to the procedure and the test is started. After the test is completed, the true volume V1 of the sample is obtained. After the catalyst layer of the above 10 plates is scraped off, the thickness D1 of the plate at this time is recorded, and the plates are placed in the density tester again. After the test is completed, the true volume V2 of the active material layer is obtained. By calculation, the apparent volume V of the catalyst layer can be obtained as V = 10 × S × (D - D1), and the true volume V3 of the catalyst layer can be obtained as V1 - V2. The porosity of the catalyst layer is ((V - V3) / V) × 100%.

[0112] The third aspect of the present application provides a battery, comprising the positive electrode sheet 521 provided in the first aspect of the present application or the positive electrode sheet 521 prepared by the method provided in the second aspect of the present application, thereby improving the capacity retention rate of the battery.

[0113] According to some embodiments of the present application, the battery further includes a negative electrode plate, which includes a negative electrode collector and a negative electrode active material layer disposed on at least one surface of the negative electrode collector, wherein the negative electrode active material layer includes a negative electrode active material.

[0114] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material layer is provided on either one or both of the two facing surfaces of the negative electrode current collector.

[0115] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base material. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0116] In some embodiments, the negative electrode active material may be a negative electrode active material for a battery that is well known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material may be selected from at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxides, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0117] In some embodiments, the negative electrode active material layer may further include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0118] In some embodiments, the negative electrode active material layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0119] In some embodiments, the negative electrode active material layer may further optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0120] In some embodiments, the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0121] According to some embodiments of the present application, the battery further includes an electrolyte, which acts as an ion conductor between the positive electrode plate 521 and the negative electrode plate. The present application does not specifically limit the type of electrolyte, and the electrolyte can be selected according to needs.

[0122] According to some embodiments of the present application, the electrolyte is an electrolyte solution comprising an electrolyte salt and a solvent.

[0123] According to some embodiments of the present application, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate and lithium tetrafluorooxalatophosphate.

[0124] According to some embodiments of the present application, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclobutane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0125] According to some embodiments of the present application, the electrolyte may optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives capable of improving certain battery properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0126] According to some embodiments of the present application, the battery further includes an isolation membrane. The present application has no particular limitation on the type of isolation membrane, and any known porous structure isolation membrane with good chemical stability and mechanical stability can be selected.

[0127] According to some embodiments of the present application, the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The isolation membrane can be a single-layer film or a multi-layer composite film, without particular limitation. When the isolation membrane is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0128] According to some embodiments of the present application, the positive electrode sheet 521 , the negative electrode sheet, and the separator may be formed into an electrode assembly through a winding process or a lamination process.

[0129] According to some embodiments of the present application, the battery may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0130] According to some embodiments of the present application, the outer packaging of the battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the battery may also be a soft shell, such as a pouch-type soft shell. The material of the soft shell may be plastic, and examples of plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0131] The present application has no particular limitation on the shape of the battery, which can be cylindrical, square, or any other shape. For example, FIG4 shows a square-structured battery 5 as an example.

[0132] According to some embodiments of the present application, referring to FIG5 , the outer packaging may include a shell 51 and a cover plate 53. The shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet 521, the negative electrode sheet and the isolation film can be formed into an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.

[0133] According to some embodiments of the present application, batteries may be assembled into a battery module. The number of batteries contained in the battery module may be one or more. The specific number may be selected by those skilled in the art based on the application and capacity of the battery module.

[0134] FIG6 shows an example battery module 4. Referring to FIG6 , within the battery module 4, multiple batteries 5 may be arranged sequentially along the length of the battery module 4. Of course, the arrangement may also be arranged in any other manner. Furthermore, the multiple batteries 5 may be secured using fasteners.

[0135] Optionally, the battery module 4 may further include a housing having a receiving space, and the plurality of batteries 5 are received in the receiving space.

[0136] According to some embodiments of the present application, the above-mentioned battery modules can also be assembled into a battery pack. The number of battery modules contained in the battery pack can be one or more, and the specific number can be selected by those skilled in the art based on the application and capacity of the battery pack.

[0137] Figures 7 and 8 illustrate an example battery pack 1. Referring to Figures 7 and 8 , the battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box comprises an upper case 2 and a lower case 3. The upper case 2 can be positioned over the lower case 3 to form an enclosed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0138] A fourth aspect of the present application provides an electrical device, comprising the battery provided in the third aspect of the present application, thereby increasing the life of the electrical device.

[0139] The electric device includes at least one of the batteries, battery modules, or battery packs provided in this application. The battery, battery module, or battery pack can be used as a power source for the electric device, or as an energy storage unit for the electric device. The electric device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc., but is not limited thereto.

[0140] As the electrical device, a battery, a battery module or a battery pack can be selected according to its usage requirements.

[0141] Figure 9 shows an example of an electric device. This device is a pure electric vehicle, hybrid electric vehicle, or 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.

[0142] As another example, the device may be a mobile phone, a tablet computer, a laptop computer, etc. Such a device is usually required to be thin and light, and may use a battery as a power source.

[0143] In order to make the technical problems, technical solutions and beneficial effects solved by the embodiments of the present application clearer, the following will be further described in detail with reference to the embodiments and drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present application and its applications. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0144] Example 1

[0145] 1. Preparation of positive electrode sheet

[0146] The lithium iron phosphate material, the conductive agent carbon black, and the binder polyvinylidene fluoride (PVDF) are fully stirred and mixed in an N-methylpyrrolidone (NMP) solvent system in a weight ratio of 97:1:2 to obtain a first positive electrode slurry. The first positive electrode slurry is evenly coated on the positive electrode current collector and dried to obtain a lithium iron phosphate layer electrode.

[0147] The cobalt nitride catalyst, carbon nanotubes, and binder polyvinylidene fluoride (PVDF) are fully stirred and mixed in an N-methylpyrrolidone (NMP) solvent system in a weight ratio of 85:10:5 to obtain a second positive electrode slurry. The second positive electrode slurry is evenly coated on the lithium iron phosphate layer electrode, dried, cold pressed, and cut for use.

[0148] An electrochemical cell was assembled using the aforementioned electrode as the positive electrode and lithium metal as the negative electrode. In a saturated O2 atmosphere, the cell was discharged to 1.0V at an electrochemical deposition current density of 250mA / g for 8 hours. Based on the Li / O2 principle, Li2O was deposited in situ on the catalyst. The positive electrode was then removed from the cell, dried, and cold-pressed a second time to obtain the positive electrode containing the lithium supplement.

[0149] 2. Preparation of negative electrode sheet

[0150] The active material artificial graphite, the conductive agent carbon black, the binder styrene-butadiene rubber (SBR), and the thickener sodium carboxymethyl cellulose (CMC-Na) are dissolved in the solvent deionized water in a weight ratio of 97.2:0.8:0.8:1.2, and mixed evenly to prepare the negative electrode slurry; the negative electrode slurry is evenly coated on the negative electrode current collector copper foil, and the negative electrode sheet is obtained after drying, cold pressing, and slitting.

[0151] 3. Isolation film

[0152] Polypropylene film is used as the isolation film.

[0153] 4. Assemble the battery

[0154] The resulting positive electrode sheet containing the lithium supplement, separator, and negative electrode sheet are stacked in order, with the separator placed between the positive and negative electrodes to provide insulation. The cells are then wound to form bare cells, which are then welded with tabs. The cells are then placed in aluminum shells and baked at 80°C to remove moisture. Electrolyte is then injected and sealed to produce an uncharged battery. The uncharged battery then undergoes a series of processes, including resting, hot and cold pressing, formation, shaping, and capacity testing, to produce a lithium-ion battery.

[0155] The preparation methods of the batteries in Examples 2 to 23 and Comparative Examples 1 and 2 are the same as those in Example 1. The differences are detailed in Table 1.

[0156] In Example 6, the electrochemical deposition process for Li2C2O4 is as follows: an electrochemical cell is assembled using a lithium iron phosphate electrode containing a catalyst layer as the positive electrode and lithium metal as the negative electrode. The cell is discharged to 1.0V in a saturated CO2 atmosphere at a current density of 250 mA / g for 8 hours. Based on the Li / CO2 principle, Li2C2O4 is deposited in situ on the catalyst. The positive electrode is then removed from the cell, dried, and cold-pressed again to obtain the positive electrode containing the lithium supplement.

[0157] The electrochemical deposition process for Li2S in Example 7 is as follows: an electrochemical cell is assembled using a lithium iron phosphate electrode containing a catalyst layer as the positive electrode, sulfur nanoparticles applied to the catalyst layer, and lithium metal as the negative electrode. The cell is discharged to 1.0V under nitrogen at a current density of 400 mA / g for 5 hours. Based on the principles of Li / / S batteries, Li2S is deposited in situ on the catalyst. The positive electrode is then removed from the cell, dried, and cold-pressed again to obtain the positive electrode containing the lithium supplement.

[0158] The electrochemical deposition process for LiF in Example 8 is as follows: an electrochemical cell is assembled using a lithium iron phosphate electrode containing a catalyst layer as the positive electrode, CF nanoparticles applied to the catalyst layer, and lithium metal as the negative electrode. Under nitrogen, the cell is discharged to 1.0V at a current density of 500 mA / g for 4 hours. Based on the principles of Li / CF batteries, LiF is deposited in situ on the catalyst. The positive electrode is then removed from the electrochemical cell, dried, and cold-pressed again to obtain the positive electrode containing the lithium supplement.

[0159] The electrochemical deposition process for Li2O in Comparative Example 1 was as follows: using a lithium iron phosphate electrode containing a catalyst layer as the positive electrode, the battery was discharged to 1.0V in a saturated O2 atmosphere at a current density of 2000 mA / g for 1 hour. Based on the Li / O2 principle, Li2O was deposited in situ on the catalyst. The positive electrode was then removed from the electrochemical cell, dried, and cold-pressed a second time to obtain the positive electrode containing the lithium supplement.

[0160] The preparation method of the positive electrode sheet in Comparative Example 2 is:

[0161] The lithium iron phosphate material, the conductive agent carbon black, and the binder polyvinylidene fluoride (PVDF) are fully stirred and mixed in an N-methylpyrrolidone (NMP) solvent system in a weight ratio of 97:1:2 to obtain a first positive electrode slurry. The first positive electrode slurry is evenly coated on the positive electrode current collector and dried to obtain a lithium iron phosphate layer electrode.

[0162] An electrochemical cell was assembled using the aforementioned electrode as the positive electrode and lithium metal as the negative electrode. In a saturated O2 atmosphere, the cell was discharged to 1.0V at an electrochemical deposition current density of 1000mA / g for 2 hours. Based on the Li / O2 principle, Li2O was deposited on the lithium iron phosphate layer. The positive electrode was then removed from the electrochemical cell, dried, and cold-pressed a second time to obtain the positive electrode containing the lithium supplement.

[0163] Performance Testing

[0164] 1. Battery capacity retention test

[0165] The battery capacity retention rate test process is as follows: at 60°C, the corresponding formed battery of Example 1 is charged at a constant current of 1 / 3C to 3.65V, then charged at a constant voltage of 3.65V to 0.05C, left for 5 minutes, and then discharged at 1 / 3C to the discharge cut-off voltage. The obtained capacity is recorded as the initial capacity C0. Repeat the above steps for the same battery and record the discharge capacity C0 of the battery after the nth cycle. n , then the battery capacity retention rate P after each cycle n =C n / C0*100%. In this test process, the first cycle corresponds to n=1, the second cycle corresponds to n=2, ... the 100th cycle corresponds to n=100. The battery capacity retention rate data corresponding to Example 1 in Table 1 is the data measured after 100 cycles under the above test conditions, that is, P 100 The value of .

[0166] 2. Lithium supplement decomposition voltage test

[0167] At 25°C, the batteries of the examples and comparative examples were charged at a constant current of 1 / 3C to 3.65V, then charged at a constant voltage of 3.65V to 0.05C, then left for 5 minutes. The battery was then charged at a constant current of 0.1C to a cutoff voltage of 4.5V. The voltage (V) and capacity (Q) data obtained were recorded and mathematically processed to obtain the dQ / dV data. A dQ / dV curve was plotted with the voltage data (V) as the horizontal axis and the corresponding dQ / dV as the vertical axis to obtain the dQ / dV curve that varies with V. The voltage corresponding to the peak of the curve in the range of 3.65V-4.5V is the decomposition voltage of the lithium supplement.

[0168] 3. Average particle size test of capacity compensator and catalyst

[0169] The capacity compensator and catalyst were distinguished using an FEI Talos FS200x transmission electron microscope combined with an energy dispersive X-ray spectrometer (EDS). Specifically, 0.01g of the capacity compensator layer powder was placed in the transmission electron microscope and the magnification was adjusted to observe the sample to ensure that the sample was clear and the quantity could be distinguished. Through EDS elemental analysis, the capacity compensator and catalyst can be distinguished by the specific metal elements in the catalyst. The particle size of the capacity compensator and catalyst particles was counted separately (no less than 10 particles), and the average was taken to obtain the average particle size of the capacity compensator and catalyst particles.

[0170] 4. Content test of capacity compensator and catalyst

[0171] The results were obtained using a TGA-601 thermogravimetric analyzer. The thermal decomposition temperature of the catalyst is approximately 1000°C-2000°C, and the thermal decomposition temperature of the capacity compensator is approximately 300°C-600°C. The capacity compensator layer on the positive electrode is scraped off and heated to 700°C-900°C in a TGA-601 thermogravimetric analyzer with nitrogen. Once the capacity compensator decomposes, the catalyst can be separated. The capacity compensator content, M2, is obtained by weight loss, and the catalyst content is (100% - M2).

[0172] 5. Catalyst specific surface area test

[0173] The thermal decomposition temperature of the catalyst is approximately 1000°C-2000°C, and the thermal decomposition temperature of the capacity compensator is approximately 300°C-600°C. The capacity compensator layer is scraped off the positive electrode and heated to 700°C-900°C. Once the capacity compensator decomposes, the catalyst can be separated. The BET surface area can be determined by the following method: Using a Gemini VII 2390 multi-station automatic surface area and pore analyzer (USA), approximately 7g of sample is placed in a 9cc bulb-equipped tube, degassed at 200°C for 2 hours, and then placed in a host device for testing to obtain the catalyst's BET (specific surface area) data.

[0174] 6. Positive electrode active material content test

[0175] The content of the positive electrode active material can be measured using a TGA-601 thermogravimetric analyzer. The capacity compensation layer and active material layer are scraped off the positive electrode sheet in sequence. The active material layer is placed in a thermogravimetric analyzer and heated by introducing oxygen. The materials in the active material layer, excluding the positive electrode active material, decompose first. Their content, M3, is determined by weight loss. The positive electrode active material content is (100% - M3).

[0176] The test results of the batteries in Examples 1 to 23 and Comparative Examples 1 and 2 are shown in Table 2.

[0177] Table 2

[0178] Conclusion: It can be seen from Table 2 that the decomposition voltage of the capacity compensating agent of the batteries in Examples 1 to 23 is lower than that in Comparative Example 1 and Comparative Example 2, and the cycle capacity retention rate of the batteries in Examples 1 to 23 is higher than that in Comparative Example 1 and Comparative Example 2. This shows that the present application can reduce the decomposition potential of the capacity compensating agent by reducing the average particle size of the capacity compensating agent, thereby improving the decomposition efficiency and utilization rate of the capacity compensating agent, thereby improving the capacity retention rate of the battery and extending the battery life.

[0179] It can be seen from Examples 1 to 5 that the smaller the particle size of the capacity compensating agent, the lower the decomposition voltage of the capacity compensating agent, and the higher the cycle capacity retention rate of the battery.

[0180] It can be seen from Examples 6 to 8 that different capacity compensators formed through different electrochemical deposition processes can reduce the decomposition voltage of the capacity compensator and improve the cycle capacity retention rate of the battery due to the smaller particle size of the capacity compensator.

[0181] It can be seen from Examples 9 to 16 that by adjusting the type and average particle size of the catalyst, the decomposition voltage of the capacity compensating agent can be reduced and the cycle capacity retention rate of the battery can be improved.

[0182] It can be seen from Examples 17 to 19 that by adjusting the content of the catalyst and the ratio of the content of the catalyst to the content of the capacity compensator, the decomposition voltage of the capacity compensator can be reduced and the cycle capacity retention rate of the battery can be improved.

[0183] It can be seen from Examples 20 to 23 that by adjusting the content of the positive electrode active material and adjusting the ratio of the capacity compensator content to the positive electrode active material content, the decomposition voltage of the capacity compensator can be reduced and the cycle capacity retention rate of the battery can be improved.

[0184] 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 positive electrode sheet, wherein: include: A positive electrode active material layer, the positive electrode active material layer comprising a positive electrode active material; A capacity compensation layer is provided on one side of the positive electrode active material layer. The capacity compensation layer comprises a catalyst and a capacity compensation agent. The average particle size of the capacity compensation agent is less than or equal to 2 μm.

2. The positive electrode sheet according to claim 1, wherein: The average particle size of the capacity compensating agent is 50nm-2μm.

3. The positive electrode sheet according to claim 1 or 2, wherein: The average particle size of the capacity compensating agent is 50nm-500nm.

4. The positive electrode sheet according to any one of claims 1 to 3, wherein: The average particle size of the catalyst is smaller than or equal to the average particle size of the capacity compensating agent.

5. The positive electrode sheet according to any one of claims 1 to 4, wherein: The average particle size of the catalyst is 50 nm-2 μm.

6. The positive electrode sheet according to any one of claims 1 to 5, wherein: The average particle size of the catalyst is 50nm-500nm.

7. The positive electrode sheet according to any one of claims 1 to 6, wherein: The BET specific surface area of ​​the catalyst is 87 m 2 / g-200m 2 / g.

8. The positive electrode sheet according to any one of claims 1 to 7, wherein: The BET specific surface area of ​​the catalyst is 130 m 2 / g-200m 2 / g.

9. The positive electrode sheet according to any one of claims 1 to 8, wherein: Based on the total mass of the capacity compensation layer, the ratio of the mass of the catalyst to the mass of the capacity compensating agent is (5-40):

100.

10. The positive electrode sheet according to any one of claims 1 to 9, wherein: Based on the total mass of the positive electrode plate, the ratio of the mass of the capacity compensating agent to the mass of the positive electrode active material is (0.5-20):

100.

11. The positive electrode sheet according to any one of claims 1 to 10, wherein: The catalyst includes a metal compound.

12. The positive electrode sheet according to claim 11, wherein: At least a portion of the surface of the metal compound has a carbon coating layer.

13. The positive electrode sheet according to claim 12, wherein: Based on the total mass of the metal compound and the carbon coating layer, the mass proportion of the carbon coating layer is 5%-30%.

14. The positive electrode sheet according to any one of claims 11 to 13, wherein: The metal compound includes at least one of a transition metal oxide, a transition metal carbide, a transition metal nitride, a transition metal sulfide or a transition metal phosphide.

15. The positive electrode sheet according to any one of claims 1 to 14, wherein: The capacity compensating agent includes a lithium supplement and / or a sodium supplement, wherein the lithium supplement includes at least one of Li2O, Li2O2, Li2CO3, Li2C2O4, Li2C4O4, Li2S, Li2Se, Li2Se2 or LiF; the sodium supplement includes at least one of Na2O, Na2O2, Na2CO3, Na2C2O4, Na2C4O4, Na2S, Na2Se, Na2Se2 or NaF.

16. The positive electrode sheet according to any one of claims 1 to 15, wherein: The positive electrode plate further includes: a positive electrode current collector, the positive electrode active material layer is located on one side of the positive electrode current collector, and the capacity compensation layer is located on a side of the positive electrode active material layer away from the positive electrode current collector.

17. A method for preparing a positive electrode sheet, wherein: include: forming a positive electrode active material layer, the positive electrode active material layer comprising a positive electrode active material; A capacity compensation layer is formed on one side of the positive electrode active material layer. The capacity compensation layer includes a catalyst and a capacity compensation agent. The average particle size of the capacity compensation agent is less than or equal to 2 μm.

18. The method according to claim 17, wherein: The method for forming the capacity compensation layer further includes: forming a catalyst layer on one side of the positive electrode active material layer, and forming the capacity compensation agent in the catalyst layer by an electrochemical deposition method.

19. The method according to claim 18, wherein: The porosity of the catalyst layer is 30%-70%.

20. The method according to claim 18 or 19, wherein: The porosity of the catalyst layer is 30%-50%.

21. A battery, wherein: A positive electrode sheet comprising the positive electrode sheet described in any one of claims 1 to 16 or a positive electrode sheet prepared by the method described in any one of claims 17 to 20.

22. An electrical device, wherein: Comprising the battery of claim 21.

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