Positive pole piece and preparation method thereof, battery and electric equipment

Abstract

The invention discloses a positive pole piece and a preparation method thereof, a battery and electric equipment, the positive pole piece comprises a positive active material layer, and the positive active material layer comprises a positive active material; the capacity compensation layer is arranged on at least one side of the positive electrode active material layer, and the capacity compensation layer comprises a capacity compensation agent and an additive. Therefore, the reaction probability of the additive and the residual alkali is improved, the residual alkali content on the surface of the capacity compensation agent is reduced, the capacity compensation effect is improved, and the cycle capacity retention ratio of the battery is improved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular, to a positive electrode plate and a preparation method thereof, a battery, and an electrical device. Background Art

[0002] Batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but are also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, as well as military equipment and aerospace and other fields. During the formation process of the battery, a solid electrolyte film (SEI film) will form on the surface of the negative electrode. The formation of the SEI film will consume active ions. In order to compensate for the irreversible capacity loss caused by the formation of the SEI film, a capacity compensator can be set on the positive electrode. During the first week of charging, the capacity compensator can release enough active ions to improve the cycle capacity retention rate of the battery. However, the residual alkali on the surface of the capacity compensator will affect the release of active ions by the capacity compensator, reduce the capacity compensation effect, and reduce the cycle capacity retention rate of the battery. Summary of the invention

[0003] In view of the technical problems existing in the background technology, the present application provides a positive electrode plate, which can increase the probability of contact between the capacity compensating agent and the additive, improve the capacity compensation effect, and improve the cycle capacity retention rate of the battery.

[0004] The first aspect of the present application provides a positive electrode plate, comprising: a positive electrode active material layer, the positive electrode active material layer comprising a positive electrode active material; a capacity compensation layer, the capacity compensation layer being arranged on at least one side of the positive electrode active material layer, the capacity compensation layer comprising a capacity compensator and an additive, the additive comprising at least one of sulfur, sulfide, selenium, selenide, phosphorus, phosphide, tellurium, iodine or boron.

[0005] The positive electrode plate proposed in the present application, the capacity compensator and the additive are simultaneously located in the capacity compensation layer, which can increase the probability of contact between the capacity compensator and the additive, increase the probability of the additive reacting with the residual alkali, reduce the residual alkali content on the surface of the capacity compensator, improve the effect of capacity compensation, and thus improve the cycle capacity retention rate of the battery. The above-mentioned types of additives are dissolved in the electrolyte to form ions, which can diffuse to the negative electrode and participate in the formation of the SEI film, thereby improving the structural stability of the SEI film, thereby reducing the DC internal resistance (DCR) of the battery while increasing the cycle life of the battery.

[0006] According to some embodiments of the present application, the additive is coated on at least a portion of the surface of the capacity compensator. Thus, the additive can react with the residual alkali on the surface of the capacity compensator to generate a fast ion conductor layer on the surface of the capacity compensator, thereby improving the ionic conductivity of the capacity compensator.

[0007] According to some embodiments of the present application, based on the total mass of the capacity compensation layer and the positive electrode active material layer, the mass proportion of the capacity compensation agent is a1, the mass proportion of the additive is a2, and 0.01≤a2 / a1≤0.45 is satisfied. Thus, while reducing the content of residual alkali on the surface of the capacity compensation agent, the probability of the additive reacting with the capacity compensation agent is reduced, and the influence of the additive on the capacity of the capacity compensation agent is reduced.

[0008] According to some embodiments of the present application, 0.5%≤a1≤12%.

[0009] According to some embodiments of the present application, 1%≤a1≤10%.

[0010] Therefore, by setting a1 within the above range, the capacity compensation effect is enhanced, and the cycle capacity retention rate of the battery is improved.

[0011] According to some embodiments of the present application, 0.05%≤a2≤2%.

[0012] According to some embodiments of the present application, 0.1%≤a2≤0.5%.

[0013] Therefore, by making a2 within the above range, the probability of contact between the additive and the capacity compensating agent is increased, the reducing effect of the additive on the capacity compensating agent is improved, the capacity compensating agent is promoted to decompose active ions, and the cycle capacity retention rate of the battery is improved.

[0014] According to some embodiments of the present application, based on the total mass of the positive electrode active material layer and the capacity compensation layer, the mass proportion of the positive electrode active material is 80%-96%, thereby improving the energy density of the battery.

[0015] According to some embodiments of the present application, the sulfide includes at least one of lithium sulfide, sodium sulfide, selenium sulfide, cobalt sulfide or nickel sulfide.

[0016] According to some embodiments of the present application, the phosphide includes at least one of lithium phosphide or sodium phosphide.

[0017] According to some embodiments of the present application, the selenide includes at least one of lithium selenide or sodium selenide.

[0018] Therefore, when the additive is the above-mentioned material, the additive can react with the residual alkali on the surface of the capacity compensator to form a fast ion conductor layer, thereby improving the ionic conductivity of the capacity compensator and the compensation effect of the active ions. At the same time, the above-mentioned types of additives can also diffuse into the negative electrode, combine with the active ions to form a dense SEI film, improve the toughness of the SEI film, reduce the DC internal resistance (DCR) of the battery, and improve the cycle life of the battery.

[0019] According to some embodiments of the present application, a carbon coating layer is formed on at least part of the surface of the capacity compensating agent, thereby improving the electronic conductivity of the capacity compensating agent, reducing the decomposition potential of the capacity compensating agent, improving the compensation effect of active ions, and improving the cycle capacity retention rate of the battery.

[0020] According to some embodiments of the present application, based on the total mass of the capacity compensator, the mass proportion of the carbon coating layer is 0.5%-10%. Thus, the electronic conductivity of the capacity compensator is improved, the decomposition potential of the capacity compensator is reduced, the compensation effect of the active ions is improved, and the cycle capacity retention rate of the battery is improved.

[0021] According to some embodiments of the present application, the capacity compensation layer further comprises the positive electrode active material, thereby reducing the difficulty of forming the capacity compensation layer and improving the energy density of the battery.

[0022] According to some embodiments of the present application, the capacity compensating agent includes a lithium supplement and / or a sodium supplement, and the lithium supplement includes Li2C2O4, Li2M1O2, Li2M2O3, Li5Fe x M 3(1-x) O4、Li6Mn y M 4(1-y) O4 or Li6Co y M 4(1-y) O4; wherein, 0.5≤x≤1, 0.5≤y≤1, M1 includes at least one of Ni, Mn, Cu, Fe, Cr or Mo, M2 includes at least one of Ni, Mn, Fe, Mo, Zr, Si, Cu, Cr or Ru, M3 includes at least one of Al, Nb, Co, Mn, Ni, Mo, Ru or Cr, M4 includes at least one of Ni, Fe, Cu or Ru, and the sodium supplement includes at least one of Na2O, Na2O2, Na2CO3, Na2C2O4, Na2C4O4, Na2S, Na2Se, Na2Se2, NaCrO2, Na3P, Na3N, Na2NiO2, Na2CuO2, Na2FeO2 or NaF. Thus, when the battery is a lithium ion battery or a sodium ion battery, the cycle capacity retention rate of the battery can be improved.

[0023] According to some embodiments of the present application, the capacity compensation layer further includes at least one of a binder and a conductive agent, thereby improving the bonding force between the capacity compensation layer and the positive electrode active material layer and reducing the risk of film layer shedding.

[0024] The second aspect of the present application provides a method for preparing a positive electrode sheet, comprising: forming a capacity compensation layer on at least one side of the positive electrode active material layer, the capacity compensation layer comprising a capacity compensator and an additive, the additive comprising at least one of sulfur, sulfide, selenium, selenide, phosphorus, phosphide, tellurium, iodine or boron. Thus, the probability of contact between the capacity compensator and the additive is increased, the probability of the additive reacting with the residual alkali is increased, the residual alkali content on the surface of the capacity compensator is reduced, the effect of capacity compensation is improved, and the cycle capacity retention rate of the battery is improved.

[0025] 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 cycle capacity retention rate of the battery and reducing the DCR of the battery.

[0026] The 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 service life of the electrical device.

[0027] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Moreover, the same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0029] Figure 1 It is a schematic diagram of the structure of the positive electrode plate of one embodiment of the present application.

[0030] Figure 2 It is a schematic structural diagram of a capacity compensating agent according to one embodiment of the present application.

[0031] Figure 3 It is a schematic structural diagram of a capacity compensating agent according to another embodiment of the present application.

[0032] Figure 4 It is a schematic structural diagram of a capacity compensating agent according to another embodiment of the present application.

[0033] Figure 5 It is a schematic structural diagram of a capacity compensating agent according to another embodiment of the present application.

[0034] Figure 6 It is a schematic structural diagram of a positive electrode plate according to another embodiment of the present application.

[0035] Figure 7It is a schematic structural diagram of a positive electrode plate according to another embodiment of the present application.

[0036] Figure 8 is a schematic diagram of a battery according to one embodiment of the present application.

[0037] Fig. 9 yes Figure 8 An exploded view of a battery according to an embodiment of the present application is shown.

[0038] Fig.10 is a schematic diagram of a battery module according to an embodiment of the present application.

[0039] Fig.11 It is a schematic diagram of a battery pack according to one embodiment of the present application.

[0040] Fig.12 yes Fig.11 An exploded view of a battery pack according to an embodiment of the present application is shown.

[0041] Fig.13 It is a schematic diagram of an electrical device using a battery as a power source according to an embodiment of the present application.

[0042] Description of reference numerals:

[0043] 1 battery; 11 shell; 12 electrode assembly; 13 cover plate; 2 battery module; 3 battery pack; 31 upper case; 32 lower case; 110 conductive agent; 120 additive; 130 capacity compensating agent; 1000 positive electrode plate; 1100 positive electrode current collector; 1200 positive electrode active material layer; 1210 first positive electrode active material layer; 1220 second positive electrode active material layer; 1300 capacity compensation layer. DETAILED DESCRIPTION

[0044] The following is a detailed description of the embodiments of the technical solution of the present application. 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 cannot be used to limit the scope of protection of the present application.

[0045] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0046] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0047] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0048] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0049] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0050] At present, from the perspective of market development, the application of batteries is becoming more and more extensive. Batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, as well as military equipment and aerospace and other fields. With the continuous expansion of battery application areas, its market demand is also constantly expanding.

[0051] During the formation process of the battery, a SEI film will form on the surface of the negative electrode. During the formation of the SEI film, a large amount of active ions will be consumed, which will reduce the cycle capacity retention rate of the battery. In order to improve the cycle capacity retention rate of the battery, the positive electrode can be pre-capacity compensated. When the positive electrode is capacity compensated, an additive rich in active ions is usually used. The additive can release active ions to compensate for the consumption of active ions. During the sintering process to prepare the capacity compensator, residual alkali will be generated on the surface of the capacity compensator. The residual alkali on the surface will affect the release of active ions by the capacity compensator and reduce the capacity compensation effect. The residual alkali in the positive electrode slurry will cause the positive electrode slurry to form a gel, and a side reaction with the electrolyte will occur, causing the battery to produce gas. Additives can react with the residual alkali on the surface of the capacity compensator to consume the residual alkali on the surface of the capacity compensator, improve the capacity compensation effect, and increase the life of the battery. However, since the content of the positive electrode active material on the positive electrode sheet is high, and the content of the additive and the capacity compensator is low, the probability of contact between the two is low, which reduces the probability of the additive reacting with the residual alkali.

[0052] The positive electrode plate proposed in the present application, the additive and the capacity compensator are located in the same layer, which increases the probability of contact between the additive and the capacity compensator, and increases the probability of the additive reacting with the residual alkali on the surface of the capacity compensator. After the additive reacts with the residual alkali, a fast ion conductor layer can be generated on the surface of the capacity compensator, thereby improving the ionic conductivity of the capacity compensator, improving the effect of capacity compensation, and improving the cycle capacity retention rate of the battery.

[0053] 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 various energy storage systems that use batteries as power sources or use batteries as energy storage elements. Electrical equipment may include, but is not limited to, mobile phones, tablets, laptops, electric toys, electric tools, battery cars, electric cars, ships, spacecraft, etc. Among them, electric toys may include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc., and spacecraft may include airplanes, rockets, space shuttles, and spacecraft, etc.

[0054] The first aspect of the present application provides a positive electrode sheet 1000, referring to Figure 1 The positive electrode plate 1000 includes a positive electrode active material layer 1200, and the positive electrode active material layer 1200 includes a positive electrode active material; a capacity compensation layer 1300, and the capacity compensation layer 1300 is arranged on at least one side of the positive electrode active material layer 1200, and the capacity compensation layer 1300 includes a capacity compensator (not shown in the figure) and an additive (not shown in the figure), and the additive includes at least one of sulfur, sulfide, selenium, selenide, phosphorus, phosphide, tellurium, iodine or boron.

[0055] The positive electrode plate 1000 proposed in the present application, the capacity compensator and the additive are simultaneously located in the capacity compensation layer 1300, which can increase the probability of contact between the capacity compensator and the additive, increase the probability of the additive reacting with the residual alkali on the surface of the capacity compensator, reduce the residual alkali content on the surface of the capacity compensator, improve the effect of capacity compensation, and thus improve the cycle capacity retention rate of the battery. By reducing the residual alkali content on the surface of the capacity compensator through additives, the risk of positive electrode slurry gelation is reduced, and the probability of the residual alkali reacting with the electrolyte to cause gas production in the battery is reduced, thereby improving the cycle life of the battery. The above-mentioned type of additive 120 dissolves in the electrolyte to form ions, participates in the formation of the SEI film, and then improves the structural stability of the SEI film, thereby reducing the battery DCR while improving the battery cycle life.

[0056] According to some embodiments of the present application, reference Figure 2 , the additive 120 can be coated on at least part of the surface of the capacity compensating agent 130. Thus, the probability of the additive 120 and the capacity compensating agent 130 contacting each other is further improved, the probability of the additive 120 reacting with the residual alkali is increased, the content of the residual alkali on the surface of the capacity compensating agent 130 is reduced, the effect of capacity compensation is improved, and the cycle capacity retention rate of the battery is improved.

[0057] According to some embodiments of the present application, based on the total mass of the capacity compensation layer and the positive electrode active material layer, the mass proportion of the capacity compensation agent is a1, and the mass proportion of the additive is a2, 0.01≤a2 / a1≤0.45, for example, it can be 0.01, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4 or 0.45, etc., or it can be a range composed of any of the above numerical values. Thus, while reducing the content of residual alkali on the surface of the capacity compensation agent 130, the probability of the additive 120 reacting with the capacity compensation agent 130 is reduced, and the influence of the additive 120 on the capacity of the capacity compensation agent 130 is reduced.

[0058] According to some embodiments of the present application, 1%≤a1+a2≤12%, for example, it can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11% or 12%, etc., or it can be a range of the above numerical values. Thereby, the effect of capacity compensation is improved, the cycle capacity retention rate of the battery is improved, the content of residual alkali on the surface of the capacity compensator 130 is reduced, the risk of positive electrode slurry gelation is reduced, the probability of battery gas production caused by the reaction of residual alkali with the electrolyte is reduced, and the life of the battery is improved. According to some specific embodiments of the present application, based on the total mass of the capacity compensation layer 1300, the total mass of the capacity compensator 130 and the additive 120 accounts for 1.1%-5.5%.

[0059] According to some embodiments of the present application, 0.5% ≤ a1 ≤ 12%, for example, it can be 0.5%, 0.7%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or 12%, etc., or it can be a range composed of any of the above values. Thereby, the effect of capacity compensation is improved and the cycle capacity retention rate of the battery is improved. According to some specific embodiments of the present application, 1% ≤ a1 ≤ 10%.

[0060] According to some embodiments of the present application, 0.05%≤a2≤2%, for example, it can be 0.05%, 0.07%, 0.1%, 0.3%, 0.5%, 0.7%, 0.9%, 1.1%, 1.3%, 1.5%, 1.7%, 1.9% or 2%, etc., or it can be a range composed of any of the above values. Thus, while reducing the content of residual alkali on the surface of the capacity compensating agent 130, the probability of the additive 120 reacting with the capacity compensating agent 130 is reduced, and the effect of the additive 120 on the capacity of the capacity compensating agent 130 is reduced. According to some specific embodiments of the present application, 0.1%≤a2≤0.5%.

[0061] According to some embodiments of the present application, based on the total mass of the positive electrode active material layer 1200 and the capacity compensation layer 1300, the mass proportion of the positive electrode active material is b, a2 / b≤0.5%, for example, it can be 0.005%, 0.01%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45% or 0.5%, etc., or it can be a range composed of any of the above numerical values. Thereby, the probability of the additive 120 reacting with the positive electrode active material is reduced, and the energy density of the battery is improved. According to some specific embodiments of the present application, 0.01%≤a2 / b≤0.3%.

[0062] According to some embodiments of the present application, 80%≤b≤96%, for example, it can be 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94% or 96%, etc., or it can be a range consisting of any of the above numerical values.

[0063] According to some embodiments of the present application, the sulfide may include at least one of lithium sulfide, sodium sulfide, selenium sulfide, cobalt sulfide or nickel sulfide.

[0064] According to some embodiments of the present application, the phosphide may include at least one of lithium phosphide or sodium phosphide.

[0065] According to some embodiments of the present application, the selenide may include at least one of lithium selenide or sodium selenide.

[0066] Therefore, when the additive 120 is the above-mentioned material, the additive 120 can react with the residual alkali on the surface of the capacity compensating agent 130 to form a fast ion conductor layer, thereby improving the ionic conductivity of the capacity compensating agent 130 and improving the compensation effect of the active ions. At the same time, the above-mentioned types of additives 120 are dissolved in the electrolyte to form ions, which diffuse to the negative electrode and combine with the active ions to form a dense SEI film, thereby improving the toughness of the SEI film, reducing the DCR of the battery, and improving the cycle life of the battery.

[0067] According to some embodiments of the present application, a carbon coating layer 110 is formed on at least part of the surface of the capacity compensating agent 130. Thus, the electronic conductivity of the capacity compensating agent 130 is improved, the decomposition potential of the capacity compensating agent 130 is reduced, the compensation effect of active ions is improved, and the cycle capacity retention rate of the battery is improved.

[0068] In the present application, the active ions may include Li + Or Na + .

[0069] According to some embodiments of the present application, reference Figure 3 The carbon coating layer 110 is coated on at least a portion of the surface of the capacity compensating agent 130 , and the additive 120 is coated on at least a portion of the surface of the carbon coating layer 110 .

[0070] According to some embodiments of the present application, reference Figure 4 The additive 120 is coated on at least a portion of the surface of the capacity compensating agent 130 , and the carbon coating layer 110 is coated on at least a portion of the surface of the additive 120 .

[0071] According to some embodiments of the present application, reference Figure 5 The carbon coating layer 110 is coated on a portion of the surface of the capacity compensating agent 130 , and the additive 120 is coated on a portion of the surface of the capacity compensating agent 130 that is not coated by the conductive agent.

[0072] As a result, the electronic conductivity and ionic conductivity of the capacity compensating agent 130 are improved, thereby enhancing the compensation effect of active ions.

[0073] According to some embodiments of the present application, when the carbon coating layer 110 and the additive 120 are simultaneously coated on the surface of the capacity compensating agent 130, the capacity compensating agent 130 can be prepared by the following method: the capacity compensating agent coated with the carbon coating layer 110 and the additive are ball-milled, and then placed in a reactor, the heating temperature is 140°C-200°C, and the heating time is 6h-15h, so as to obtain the capacity compensating agent 130 with the surface coated with the carbon coating layer 110 and the additive 120. According to some specific embodiments of the present application, the heating temperature can be 150°C, 160°C, 170°C, 180°C, 190°C or 200°C, or can be a range composed of any of the above values. According to some specific embodiments of the present application, the heating time can be 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h or 16h, or can be a range composed of any of the above values.

[0074] According to some embodiments of the present application, based on the total mass of the capacity compensating agent 130, the mass proportion of the carbon coating layer 110 can be 0.5%-10%, for example, 0.5%, 0.7%, 1%, 1.3%, 1.6%, 1.8%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%, etc., or can be a range composed of any of the above values. Thus, the electronic conductivity of the capacity compensating agent 130 is improved, the decomposition potential of the capacity compensating agent 130 is reduced, the compensation effect of the active ions is improved, and the cycle capacity retention rate of the battery is improved.

[0075] According to some embodiments of the present application, the capacity compensation layer 1300 may further include the positive electrode active material. Thus, a small amount of positive electrode active material is added to the capacity compensation layer 1300, the thickness of the capacity compensation layer 1300 is increased, the difficulty of forming the capacity compensation layer 1300 is reduced, and the energy density of the battery is increased.

[0076] According to some embodiments of the present application, reference Figure 1 The positive electrode sheet 1000 further includes a positive current collector 1100 , the positive active material layer 1200 is located on at least one side of the positive current collector 1100 , and the capacity compensation layer 1300 is located on a side of the positive active material layer 1200 away from the positive current collector 1100 .

[0077] According to some embodiments of the present application, reference Figure 6 The positive electrode sheet 1000 further includes a positive current collector 1100 , the positive active material layer 1200 is located on at least one side of the positive current collector 1100 , and the capacity compensation layer 1300 is located between the positive active material layer 1200 and the positive current collector 1100 .

[0078] According to some embodiments of the present application, reference Figure 7 The positive electrode sheet 1000 also includes a positive current collector 1100, the positive active material layer 1200 includes a first positive active material layer 1210 and a second positive active material layer 1220, the first positive active material layer 1210 is located on at least one side of the positive current collector 1100, the second positive active material layer 1220 is located on a side of the first positive active material layer 1210 away from the positive current collector 1100, and the capacity compensation layer 1300 is located between the first positive active material layer 1210 and the second positive active material layer 1220.

[0079] Therefore, the battery containing the positive electrode sheet 1000 having the above structure has excellent cycle capacity retention rate and capacity.

[0080] According to some embodiments of the present application, the positive electrode sheet can be prepared by gravure primer coating. Specifically, the capacity compensation layer and the positive electrode active material layer are formed on the positive electrode current collector by gravure coating.

[0081] According to other embodiments of the present application, the capacity compensation layer and the positive electrode active material layer may be formed simultaneously by a double-layer coating die.

[0082] According to other embodiments of the present application, the positive electrode active material layer and the capacity compensation layer may be formed by multiple coating processes.

[0083] As an example, the positive electrode current collector 1100 may be a metal foil or a composite current collector. For example, as the metal foil, aluminum foil may be used. The composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer 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, the capacity compensating agent 130 includes a lithium supplement and / or a sodium supplement, and the lithium supplement includes Li2C2O4, Li2M1O2, Li2M2O3, Li5Fe x M 3(1-x) O4、Li6Mn y M 4(1-y) O4 or Li6Co y M 4(1-y)O4; wherein, 0.5≤x≤1, 0.5≤y≤1, M1 includes at least one of Ni, Mn, Cu, Fe, Cr or Mo, M2 includes at least one of Ni, Mn, Fe, Mo, Zr, Si, Cu, Cr or Ru, M3 includes at least one of Al, Nb, Co, Mn, Ni, Mo, Ru or Cr, M4 includes at least one of Ni, Fe, Cu or Ru, and the sodium supplement includes at least one of Na2O, Na2O2, Na2CO3, Na2C2O4, Na2C4O4, Na2S, Na2Se, Na2Se2, NaCrO2, Na3P, Na3N, Na2NiO2, Na2CuO2, Na2FeO2 or NaF. Therefore, when the battery is a lithium ion battery, the capacity compensating agent 130 can be a lithium supplementing agent, and the additive 120 can react with the residual alkali on the surface of the lithium supplementing agent to reduce the content of the residual alkali on the surface of the lithium supplementing agent, improve the capacity compensation effect of the lithium supplementing agent, and improve the cycle capacity retention rate of the battery; when the battery is a sodium ion battery, the capacity compensating agent 130 can be a sodium supplementing agent, and the additive 120 can react with the residual alkali on the surface of the sodium supplementing agent to reduce the content of the residual alkali on the surface of the sodium supplementing agent, improve the capacity compensation effect of the sodium supplementing agent, and improve the cycle capacity retention rate of the battery.

[0085] According to some embodiments of the present application, the capacity compensation layer 1300 may further include at least one of a binder and a conductive agent.

[0086] According to some embodiments of the present application, based on the total mass of the capacity compensation layer 1300 and the positive electrode active material layer 1200, the mass proportion of the binder can be 0.8%-5%, for example, it can be 0.8%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%, etc., or it can be a range composed of any of the above numerical values. Thereby, the bonding force between the capacity compensation layer 1300 and the positive electrode active material layer 1200 is improved, and the risk of film shedding is reduced. According to some specific embodiments of the present application, based on the total mass of the capacity compensation layer 1300, the mass proportion of the binder can be 0.8%-2.2%.

[0087] According to some embodiments of the present application, the binder may include at least one of polypropylene, polyethylene, polyvinylidene fluoride, polytetrafluoroethylene, polyvinylidene fluoride-hexafluoropropylene or polyhexafluoropropylene. Thus, the bonding force between the capacity compensation layer 1300 and the positive electrode active material layer 1200 is improved, and the risk of film layer shedding is reduced.

[0088] According to some embodiments of the present application, based on the total mass of the capacity compensation layer 1300 and the positive electrode active material layer 1200 , the mass proportion of the conductive agent may be 0.3%-10%.

[0089] According to some embodiments of the present application, the conductive agent may include at least one of superconducting carbon, carbon nanotubes, graphite, nanofibers or graphene. Thus, the conductive agent of the above type can improve the electronic conductivity of the capacity compensating agent 130, reduce the decomposition potential of the capacity compensating agent 130, improve the compensation effect of active ions, and improve the cycle capacity retention rate of the battery.

[0090] When the battery is a lithium-ion battery, as an example, the positive electrode active material may adopt a 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: a lithium-containing phosphate with an olivine structure, a lithium transition metal oxide, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, 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 0.2 O2 (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, etc. Examples of lithium-containing phosphates with an olivine structure 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.

[0091] 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 analog.

[0092] Examples of the layered transition metal oxides include:

[0093] Na 1-x Cu h Fe k Mn l M 1 m O 2-y , where M 1 It is 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;

[0094] 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;

[0095] Na a Li b Ni c Mn d Fe e O2, of which 0.67 <a≤1,0<b<0.2,0<c<0.3,0.67<d+e<0.8,b+c+d+e=1。

[0096] Examples of the polyanionic compound include:

[0097] 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 1is one or more of F, Cl, and Br, 0 < f ≤ 4, 0 < g ≤ 2, 1 ≤ i ≤ 3, 0 ≤ j ≤ 2;

[0098] 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;

[0099] Na p M 5 q (SO4)3, where M 5 is one or more of Mn, Fe, Co, Ni, Cu, and Zn, 0 < p ≤ 2, 0 < q ≤ 2;

[0100] Na s Mn t Fe 3-t (PO4)2(P2O7), where 0 < s ≤ 4, 0 ≤ t ≤ 3, for example, t is 0, 1, 1.5, 2, or 3.

[0101] As an example of the above Prussian blue analogues, for example, the following can be listed:

[0102] A u M 6 v [M 7 (CN)6] w ·xH2O, where A is H + 、NH4 + 、an alkali metal cation, and an alkaline earth metal cation, M 6 and M 7 are each independently one or more of transition metal cations, 0 < u ≤ 2, 0 < v ≤ 1, 0 < w ≤ 1, 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+ among one or more, M 6 and M 7Each is independently a cation of one or more transition metal elements selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn and W.

[0103] The modified compounds of the above materials may be doping-modified and / or surface-coated modified materials.

[0104] In some embodiments, the positive electrode sheet 1000 can be prepared in the following manner: the components for preparing the positive electrode sheet 1000, such as the positive electrode active material, the capacity compensating agent 130, the additive 120, the conductive agent, the binder and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode collector 1100, and after drying, cold pressing and other processes, the positive electrode sheet 1000 can be obtained.

[0105] The second aspect of the present application also provides a method for preparing a positive electrode plate, comprising forming a capacity compensation layer on at least one side of a positive electrode active material layer, wherein the capacity compensation layer comprises a capacity compensating agent and an additive.

[0106] According to some embodiments of the present application, reference Figure 3 When the carbon coating layer 110 is coated on at least a portion of the surface of the capacity compensating agent 130, and the additive 120 is coated on at least a portion of the surface of the carbon coating layer 110, the preparation method of the capacity compensating agent 130 can be to mix the capacity compensating agent 130 and the carbon coating layer 110 in water evenly, spray-dry and then calcine under an inert atmosphere to obtain the capacity compensating agent 130 coated with the carbon coating layer 110, and then grind and mix the capacity compensating agent 130 coated with the carbon coating layer 110 and the additive 120 evenly, and then place them in a reactor, the heating temperature can be 140°C-160°C, and the heating time can be 20h-30h, so as to obtain the capacity compensating agent 130 in which the additive 120 is coated on at least a portion of the surface of the carbon coating layer 110 and the carbon coating layer 110 is coated on at least a portion of the surface of the capacity compensating agent 130. According to some specific embodiments of the present application, the heating temperature may be 140°C, 145°C, 150°C, 155°C or 160°C, etc., or may be a range consisting of any of the above values. According to some specific embodiments of the present application, the heating time may be 20h, 22h, 24h, 26h, 28h or 30h, etc., or may be a range consisting of any of the above values.

[0107] According to some embodiments of the present application, reference Figure 4, when the additive 120 is coated on at least part of the surface of the capacity compensating agent 130, and the carbon coating layer 110 is coated on at least part of the surface of the additive 120, the preparation method of the capacity compensating agent 130 can be to grind and mix the capacity compensating agent 130 and the additive 120 evenly, place them in a reactor, and heat them at a temperature of 140°C-160°C for 20h-30h, and then ball mill them with the carbon coating layer 110 to obtain the capacity compensating agent 130 in which the additive 120 is coated on at least part of the surface of the capacity compensating agent 130 and the carbon coating layer 110 is coated on at least part of the surface of the additive 120. According to some specific embodiments of the present application, the heating temperature can be 140°C, 145°C, 150°C, 155°C or 160°C, or can be a range composed of any of the above values. According to some specific embodiments of the present application, the heating time can be 20h, 22h, 24h, 26h, 28h or 30h, or can be a range composed of any of the above values.

[0108] According to some embodiments of the present application, reference Figure 5 , when the carbon coating layer 110 is coated on a portion of the surface of the capacity compensating agent 130, and the additive 120 is coated on a portion of the surface of the capacity compensating agent 130 not coated by the carbon coating layer 110, the preparation method of the capacity compensating agent 130 may be to ball-mill the capacity compensating agent 130 coated with the carbon coating layer 110 and the additive 120, and then place them in a reactor, and heat them at a temperature of 140°C-200°C for a heating time of 6h-15h to obtain the capacity compensating agent 130 whose surface is coated with the carbon coating layer 110 and the additive 120. According to some specific embodiments of the present application, the heating temperature may be 150°C, 160°C, 170°C, 180°C, 190°C or 200°C, or may be a range consisting of any of the above numerical values. According to some specific embodiments of the present application, the heating time can be 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h or 16h, etc., or can be a range consisting of any of the above numerical values.

[0109] The third aspect of the present application provides a battery, comprising the positive electrode sheet 1000 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 cycle capacity rate of the battery and reducing the DCR of the battery.

[0110] [Negative electrode]

[0111] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.

[0112] As an example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.

[0113] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, copper foil may be used. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0114] In some embodiments, the negative electrode active material may adopt the negative electrode active material for the battery 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, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, 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.

[0115] In some embodiments, the negative electrode film 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).

[0116] In some embodiments, the negative electrode film layer may further include a conductive agent, which may be selected from at least one of superconducting carbon (SuperP), acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

[0117] In some embodiments, the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0118] In some embodiments, the negative electrode sheet can be prepared in the following manner: 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 collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0119] [Electrolytes]

[0120] The electrolyte plays a role in conducting ions between the positive electrode plate 1000 and the negative electrode plate. The present application has no specific restrictions on the type of electrolyte, which can be selected according to needs.

[0121] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.

[0122] In some embodiments, 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.

[0123] In some embodiments, the solvent can 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, cyclopentane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0124] In some embodiments, the electrolyte may further include additives, such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.

[0125] [Isolation film]

[0126] In some embodiments, the battery further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical stability and mechanical stability can be selected.

[0127] In some embodiments, 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] In some embodiments, the positive electrode sheet 1000 , the negative electrode sheet, and the separator may be formed into an electrode assembly by a winding process or a lamination process.

[0129] In some embodiments, the battery may include an outer packaging, which may be used to encapsulate the electrode assembly and the electrolyte.

[0130] In some embodiments, 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 package, such as a bag-type soft package. The material of the soft package may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0131] The present application has no particular limitation on the shape of the battery, which may be cylindrical, square or any other shape. For example, Figure 8 A square-structured battery 1 is shown as an example.

[0132] In some embodiments, the battery 1 may include an outer package for packaging the positive electrode sheet, the negative electrode sheet, and the electrolyte.

[0133] In some embodiments, reference Fig. 9 The positive electrode sheet, the negative electrode sheet and the isolation film can be formed into an electrode assembly 12 through a winding process or a lamination process.

[0134] In some embodiments, reference Fig. 9 The outer package may include a shell 11 and a cover plate 13. The shell 11 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 11 has an opening connected to the receiving cavity, and the cover plate 13 can be covered on the opening to close the receiving cavity.

[0135] In some embodiments, the outer packaging of the battery 1 may be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell.

[0136] The outer packaging of the battery 1 may also be a soft package, such as a bag-type soft package. The material of the soft package may be plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0137] In some embodiments, the battery 1 can be assembled into a battery module 2 , and the battery module 2 can contain multiple batteries 1 , and the specific number can be adjusted according to the application and capacity of the battery module 2 .

[0138] In some embodiments, the outer packaging of the battery 1 may include a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell.

[0139] Fig.10 2 is an example of a battery module 2. Fig.10 In the battery module 2, the multiple batteries 1 can be arranged in sequence along the length direction of the battery module 2. Of course, they can also be arranged in any other manner. Further, the multiple batteries 1 can be fixed by fasteners.

[0140] The battery module 2 may also include a housing having a storage space, in which a plurality of batteries 1 are stored. In some embodiments, the battery modules may be assembled into a battery pack, and the number of battery modules contained in the battery pack may be adjusted according to the application and capacity of the battery pack.

[0141] Fig.11 and Fig.12 The battery pack 3 is used as an example. Fig.11 and 12 The battery pack 3 may include a battery box and a plurality of battery modules 2 disposed in the battery box. The battery box includes an upper box body 31 and a lower box body 32. The upper box body 31 can cover the lower box body 32 and form a closed space for accommodating the battery modules 2. The plurality of battery modules 2 can be arranged in the battery box in any manner.

[0142] The fourth aspect of the present application provides an electrical device, comprising the battery provided in the third aspect of the present application, thereby improving the energy density and cycle life of the electrical device.

[0143] As an example, the battery can be used as a power source for an electrical device or as an energy storage unit for an electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0144] As the electrical device, a battery can be selected according to its usage requirements.

[0145] Fig.13 The power consumption device is taken as an example. The power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the power consumption device's requirements for high power and high energy density of the battery, a battery pack or a battery module can be used.

[0146] As another example, the device may be a mobile phone, a tablet computer, a notebook computer, etc. The device is usually required to be thin and light, and a battery may be used as a power source.

[0147] 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 the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present application and its applications. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0148] Example 1

[0149] 1. Preparation of positive electrode sheet

[0150] LiFePO4 (LFP), conductive agent Super P, and binder polyvinylidene fluoride (PVDF) are stirred and mixed in N-methylpyrrolidone (NMP) solvent at a weight ratio of 96:2:2 to obtain a first slurry;

[0151] The capacity compensator Li5FeO4 / C was ball-milled with sulfur, and the mass ratio of Li5FeO4 / C to sulfur was 1:0.4. After ball-milling, it was placed in a reactor and reacted at 155°C for 12 hours. Li5FeO4, PVDF, Super P and LFP coated with carbon and sulfur on the surface were fully stirred and mixed in NMP at a weight ratio of 35:2:2:61 to obtain a second slurry, in which the mass proportion of carbon was 4% based on the total mass of the capacity compensator Li5FeO4 / C. The first slurry and the second slurry were formed on the positive electrode collector by coating, and cold pressed to obtain a positive electrode sheet. The positive electrode active material layer was located on the surface of the positive electrode collector, and the mass of the positive electrode active material layer was 20.384g / cm 2 The capacity compensation layer is located on the surface of the positive electrode active material layer away from the positive electrode current collector. The mass of the capacity compensation layer is 0.416 g / cm 2 .

[0152] 2. Preparation of negative electrode sheet

[0153] Active material artificial graphite, conductive agent acetylene black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC-Na) are mixed in deionized water in a weight ratio of 96.5:0.7:1.8:1, and then coated on copper foil, dried, and cold pressed to obtain a negative electrode sheet.

[0154] 3. Preparation of electrolyte

[0155] In an argon atmosphere glove box (H2O<0.1ppm, O2<0.1ppm), ethylene carbonate and ethyl methyl carbonate were mixed in a mass ratio of 30:70 to obtain an organic solvent, and the fully dried electrolyte salt LiPF6 was dissolved in the above solvent. After mixing evenly, an electrolyte solution with a concentration of 1 mol / L was obtained.

[0156] 4. Isolation film

[0157] Polypropylene film is used as the isolation film.

[0158] 5. Preparation of batteries

[0159] The positive electrode sheet, the separator, and the negative electrode sheet are stacked in order, so that the separator is between the positive and negative electrode sheets to play an isolating role, and then they are wound to obtain an electrode assembly; the electrode assembly is placed in an outer package, and the prepared electrolyte is injected into the dried lithium-ion battery. After vacuum packaging, standing, forming, and shaping processes, a lithium-ion battery is obtained.

[0160] The preparation methods of the batteries in Examples 2 to 17 and Comparative Example 1 are the same as those in Example 1, and the differences are detailed in Table 1.

[0161] The difference between Example 2-11 and Example 1 is that the mass ratio of the capacity compensating agent Li5FeO4 / C to the additive sulfur, the mass of the positive electrode active material layer and the mass of the capacity compensation layer are adjusted accordingly, and the rest is the same as Example 1.

[0162] The difference between Examples 12-15 and Example 3 is that the weight ratios of the substances in the first slurry and the second slurry are adjusted accordingly, and the rest is the same as Example 3. Among them, in Example 12, the weight ratio of LFP, Super P and PVDF in the first slurry is 97.9:0.1:2, and the weight ratio of Li5FeO4, PVDF, Super P and LFP coated with carbon and sulfur in the second slurry is 35:0.1:2:62.9; in Example 13, the weight ratio of LFP, Super P and PVDF in the first slurry is 97.7:0.3:2, and the weight ratio of Li5FeO4, PVDF, Super P and LFP coated with carbon and sulfur in the second slurry is 35:0.3:2:62.7; in Example 14, the weight ratio of LFP, Super P and PVDF in the first slurry is 97.3:0.7:2, and the weight ratio of Li5FeO4, PVDF, Super P and LFP coated with carbon and sulfur in the second slurry is 35:0.7:2:62.3; in Example 15, the weight ratio of LFP, Super P and PVDF in the first slurry is 97.7:0.3:2, and the weight ratio of Li5FeO4, PVDF, Super P and LFP coated with carbon and sulfur in the second slurry is 35:0.7:2:62.3. The weight ratio of P and PVDF is 88:10:2, and the weight ratio of Li5FeO4 coated with carbon and sulfur, PVDF, Super P and LFP in the second slurry is 35:10:2:53.

[0163] The preparation method of the battery in Comparative Example 1 is the same as that in Example 1, except that LFP, Super P, PVDF, Li5FeO4 / C and additive sulfur are fully stirred and mixed in an NMP solvent in a weight ratio of 90.8:2:2:5:0.2, coated on an aluminum foil, and cold pressed to obtain a positive electrode active material layer containing the positive electrode active material, additives and capacity compensator.

[0164]

[0165]

[0166] Performance Testing

[0167] 1. DCR test

[0168] Maintaining an ambient temperature of 25°C, charge and discharge at a rate of 0.33C for 3 cycles with a cut-off voltage of 2.5V to 3.65V. Take the discharge capacity of the third cycle as the standard capacity C0. Then charge with 0.33C0 to 50% C0 (50% SOC), let stand for 30 minutes, and then discharge at a current of I=4C0 for 30 seconds. Record the voltage difference ΔU before and after 4C0 discharge, DCR=ΔU / I.

[0169] 2. Cycle capacity retention rate test method

[0170] (1) At 45°C, charge the lithium-ion battery to 3.65V at a constant current of 1 / 3C, charge it to a current of 0.05C at a constant voltage of 3.65V, let it stand for 5 minutes, and then discharge it to 2.5V at a constant current of 1 / 3C, and record the discharge capacity C0; (2) Then charge the lithium-ion battery to 3.65V at a constant current of 1.0C, let it stand for 5 minutes, and then discharge it to 2.5V at a constant current of 1 / 3C, and record the discharge capacity C1. Repeat the above step (2) 200 times, and record the discharge capacity C1 of the lithium-ion battery after the 200th cycle. 200 , capacity retention rate P 200 =C 200 / C0×100%.

[0171] The test results of the batteries in Examples 1 to 17 and Comparative Example 1 are shown in Table 2.

[0172] Table 2

[0173]

[0174] Conclusion: The cycle capacity retention rates of the batteries in Examples 1 to 17 are all higher than those in Comparative Example 1, indicating that the battery proposed in the present application can improve the capacity compensation effect of the capacity compensating agent and thereby improve the cycle capacity retention rate of the battery by placing the capacity compensating agent and the additive in the same layer.

[0175] It can be seen from Examples 1 to 5 that by adjusting the content of the capacity compensating agent, the battery cycle capacity retention rate can be increased, the DCR of the battery can be reduced, and the overall performance of the battery can be improved.

[0176] It can be seen from Examples 6 to 11 that by adjusting the content of the additive, the battery cycle capacity retention rate can be increased, the DCR of the battery can be reduced, and the overall performance of the battery can be improved.

[0177] It can be seen from Examples 1 to 11 that by adjusting the ratio of the content of the additive to the content of the positive electrode active material, the cycle capacity retention rate of the battery can be increased, the DCR of the battery can be reduced, and the overall performance of the battery can be improved.

[0178] It can be seen from Examples 12 to 15 that by adjusting the content of the conductive agent in the capacity compensation layer, the cycle capacity retention rate of the battery can be increased, the DCR of the battery can be reduced, and the overall performance of the battery can be improved.

[0179] 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 replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate 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, characterized in that: include: A positive electrode active material layer, the positive electrode active material layer comprising a positive electrode active material; A capacity compensation layer, wherein the capacity compensation layer is disposed on at least one side of the positive electrode active material layer, and the capacity compensation layer includes a capacity compensator and an additive, wherein the additive includes at least one of sulfur, sulfide, selenium, selenide, phosphorus, phosphide, tellurium, iodine or boron.

2. The positive electrode sheet according to claim 1, characterized in that: The additive is coated on at least a portion of the surface of the capacity compensating agent.

3. The positive electrode sheet according to claim 1 or 2, characterized in that: Based on the total mass of the capacity compensation layer and the positive electrode active material layer, the mass proportion of the capacity compensation agent is a1, the mass proportion of the additive is a2, and 0.01≤a2 / a1≤0.45 is satisfied.

4. The positive electrode sheet according to claim 3, characterized in that: 0.5%≤a1≤12%, optionally 1%≤a1≤10%.

5. The positive electrode sheet according to claim 3 or 4, characterized in that: 0.05%≤a2≤2%, optionally 0.1%≤a2≤0.5%.

6. The positive electrode sheet according to any one of claims 3 to 5, characterized in that: Based on the total mass of the positive electrode active material layer and the capacity compensation layer, the mass proportion of the positive electrode active material is 80%-96%.

7. The positive electrode sheet according to any one of claims 3 to 6, characterized in that: Satisfy at least one of the following conditions: The sulfide includes at least one of lithium sulfide, sodium sulfide, selenium sulfide, cobalt sulfide or nickel sulfide; The phosphide comprises at least one of lithium phosphide or sodium phosphide; The selenide includes at least one of lithium selenide or sodium selenide.

8. The positive electrode sheet according to any one of claims 1 to 7, characterized in that: A carbon coating layer is formed on at least a portion of the surface of the capacity compensating agent.

9. The positive electrode sheet according to claim 8 of the group is characterized in that: Based on the total mass of the capacity compensating agent, the mass proportion of the carbon coating layer is 0.5%-10%.

10. The positive electrode sheet according to any one of claims 1 to 9, characterized in that: The capacity compensation layer also includes the positive electrode active material.

11. The positive electrode sheet according to any one of claims 1 to 10, characterized in that: The capacity compensating agent includes a lithium supplement and / or a sodium supplement, and the lithium supplement includes Li2C2O4, Li2M1O2, Li2M2O3, Li5Fe x M 3(1-x) O4、Li6Mn y M 4(1-y) O4 or Li6Co y M 4(1-y) O4; wherein, 0.5≤x≤1, 0.5≤y≤1, M1 includes at least one of Ni, Mn, Cu, Fe, Cr or Mo, M2 includes at least one of Ni, Mn, Fe, Mo, Zr, Si, Cu, Cr or Ru, M3 includes at least one of Al, Nb, Co, Mn, Ni, Mo, Ru or Cr, M4 includes at least one of Ni, Fe, Cu or Ru, and the sodium supplement includes at least one of Na2O, Na2O2, Na2CO3, Na2C2O4, Na2C4O4, Na2S, Na2Se, Na2Se2, NaCrO2, Na3P, Na3N, Na2NiO2, Na2CuO2, Na2FeO2 or NaF.

12. A method for preparing a positive electrode sheet, characterized in that: include: A capacity compensation layer is formed on at least one side of the positive electrode active material layer, wherein the capacity compensation layer includes a capacity compensator and an additive, wherein the additive includes at least one of sulfur, sulfide, selenium, selenide, phosphorus, phosphide, tellurium, iodine or boron.

13. A battery, characterized in that: A positive electrode sheet comprising the positive electrode sheet described in any one of claims 1 to 11 or a positive electrode sheet prepared by the method of claim 12.

14. An electrical device, characterized in that: Comprising the battery of claim 13.

Images