Positive electrode sheet and method for manufacturing the same, battery and power consumption device

Abstract

The present application provides a positive electrode sheet (100) and a manufacturing method thereof, a battery, and a power consuming device, the positive electrode sheet (100) including a positive electrode current collector (11), and including a polymer and an organic solvent on at least one side of the positive electrode sheet (100) away from the positive electrode current collector (11), the organic solvent being located within the polymer, and the electrochemical oxidation reaction potential window of the organic solvent being higher than 4V.

Description

[Technical Field]

[0001] The present application relates to the field of batteries, and more particularly to positive electrode sheets and methods for producing the same, batteries, and power consuming devices. [Background technology]

[0002] Secondary batteries are not only used in energy storage power systems such as hydroelectric, thermal, wind and solar power plants, but are also widely used in electric vehicles such as electric bicycles, electric motorcycles and electric cars, as well as in military equipment and aerospace. However, conventional secondary batteries are prone to abnormal increases in charge capacity under high-rate and high-cutoff voltage (>4V) charging conditions, which poses the risk of overcharging. Summary of the Invention

[0003] In view of the technical problems existing in the background art, the present application provides a positive electrode sheet intended to reduce the risk of overcharging of a secondary battery containing the positive electrode sheet.

[0004] To achieve the above object, one aspect of the present application provides a positive electrode sheet, comprising a polymer and an organic solvent on at least one side of the positive electrode sheet away from the positive electrode current collector, the organic solvent being located within the polymer, and the organic solvent having an electrochemical oxidation reaction potential window of greater than 4 V.

[0005] The present application has at least the following beneficial effects: By using a positive electrode sheet containing a polymer and an organic solvent, the organic solvent is located within the polymer, and the polymer and organic solvent are located on at least one side of the positive electrode sheet away from the positive electrode current collector. The organic solvent-filled polymer can block direct contact between the positive electrode active material and the electrolyte solvent in the battery, thereby preventing oxidative decomposition of the electrolyte solvent. At the same time, the electrochemical oxidation potential window of the organic solvent is higher than 4 V, i.e., under high cutoff voltage (>4 V) charging conditions, the organic solvent does not undergo oxidation reactions at the positive electrode side, thereby preventing side reactions at the positive electrode side. Furthermore, under high-rate charging, the organic solvent is not easily excited to undergo oxidative decomposition, so additional electrons are not generated and reach the negative electrode side, preventing an abnormal increase in the battery's charge capacity and reducing the risk of battery overcharging.

[0006] In some embodiments, the positive electrode sheet includes a positive electrode active material layer provided on at least one side of the positive electrode current collector, the positive electrode active material layer including positive electrode active material particles and a polymer layer on the surfaces of the positive electrode active material particles, the polymer layer including the polymer and the organic solvent. Thus, by forming a polymer layer including a polymer and an organic solvent on the surfaces of the positive electrode active material particles, the polymer layer can block direct contact between the positive electrode active material and the electrolyte solvent in the battery, thereby avoiding oxidative decomposition of the electrolyte solvent and reducing the risk of the battery being overcharged.

[0007] In some embodiments, the positive electrode active material layer further includes at least one of a binder and a conductive agent, which can improve the conductivity of the positive electrode active material layer and the bonding strength with the positive electrode current collector.

[0008] In some embodiments, the mass ratio of the positive electrode active material particles to the binder and the conductive agent is (90-100):(0-5):(0-5), and optionally (95-98.5):(0.5-2):(0.5-2), which can improve the conductivity of the positive electrode active material layer and the bond strength with the positive electrode current collector.

[0009] In some embodiments, the thickness of the positive electrode active material layer is 30 μm to 60 μm, and optionally 30 μm to 50 μm, thereby enabling a positive electrode active material layer of this thickness to improve the energy density of the battery.

[0010] In some embodiments, the thickness of the polymer layer is 0.01 μm to 2 μm, and optionally 0.01 μm to 1 μm, so that a polymer layer of this thickness is formed on the surface of the positive electrode active material particles, which not only blocks direct contact between the positive electrode active material and the electrolyte solvent in the battery, but also prevents oxidative decomposition of the electrolyte solvent and reduces the impedance of the positive electrode sheet.

[0011] In some embodiments, the mass ratio of the polymer to the organic solvent is (0.1 to 99):(1 to 99.9), and optionally (0.1 to 15):(85 to 99.9), which effectively blocks direct contact between the positive electrode active material and the electrolyte solvent in the battery, avoids oxidative decomposition of the electrolyte solvent, and reduces the risk of overcharging the battery.

[0012] In some embodiments, the polymer layer further comprises an electrolyte salt, which can improve the ionic conductivity of the polymer layer.

[0013] In some embodiments, the concentration of the electrolyte salt in the polymer layer is 0.1 mol / L to 10 mol / L, and optionally 0.5 mol / L to 5 mol / L, relative to the total amount of the organic solvent and the electrolyte salt, thereby improving the ionic conductivity of the polymer layer.

[0014] In some embodiments, the polymer layer further comprises at least one of a film-forming additive and an adsorption additive, which can improve the cycling stability of the positive electrode sheet.

[0015] In some embodiments, the film-forming additive has an electrochemical oxidation potential window of 4 V or less.

[0016] In some embodiments, the electrochemical oxidation potential window of the adsorption additive is greater than 4V.

[0017] In some embodiments, the mass ratio of the polymer to the film-forming additive and the adsorption additive is (10-100):(0-90):(0-90), and optionally (30-80):(20-70):(20-70), which can improve the cycle stability of the positive electrode sheet.

[0018] In some embodiments, the positive electrode sheet includes a positive electrode active material layer and a protective layer, the positive electrode active material layer being provided on at least one side of the positive electrode current collector, the protective layer being provided on at least one side of the positive electrode active material layer, and the protective layer including the polymer and the organic solvent. Thus, by forming the protective layer including the polymer and the organic solvent on the positive electrode active material layer, the protective layer can block direct contact between the positive electrode active material and the electrolyte solvent in the battery, thereby avoiding oxidative decomposition of the electrolyte solvent and reducing the risk of the battery being overcharged.

[0019] In some embodiments, the thickness of the protective layer is 0.1 μm to 40 μm, optionally 1 μm to 20 μm, and further optionally 1 μm to 10 μm, whereby a protective layer of this thickness is formed on the surface of the positive electrode active material layer, which not only prevents direct contact between the positive electrode active material and the electrolyte solvent in the battery, but also prevents oxidative decomposition of the electrolyte solvent and reduces the impedance of the positive electrode sheet.

[0020] In some embodiments, the mass ratio of the polymer to the organic solvent in the protective layer is (0.1 to 99):(1 to 99.9), and optionally (0.1 to 15):(85 to 99.9), which effectively blocks direct contact between the positive electrode active material and the electrolyte solvent in the battery, avoids oxidative decomposition of the electrolyte solvent, and reduces the risk of overcharging the battery.

[0021] In some embodiments, the protective layer further comprises an electrolyte salt, which can improve the ionic conductivity of the protective layer.

[0022] In some embodiments, the concentration of the electrolyte salt in the protective layer relative to the total amount of the organic solvent and the electrolyte salt is 0.1 mol / L to 10 mol / L, and optionally 0.5 mol / L to 5 mol / L, thereby improving the ionic conductivity of the protective layer.

[0023] In some embodiments, the protective layer further comprises at least one of a film-forming additive and an adsorption additive, which can improve the cycle stability of the positive electrode sheet.

[0024] In some embodiments, the film-forming additive has an electrochemical oxidation potential window of 4 V or less.

[0025] In some embodiments, the electrochemical oxidation potential window of the adsorption additive is greater than 4V.

[0026] In some embodiments, the mass ratio of the polymer to the film-forming additive and the adsorption additive is (10-100):(0-90):(0-90), and optionally (30-80):(20-70):(20-70), which can improve the cycle stability of the positive electrode sheet.

[0027] In some embodiments, the organic solvent is a carbonate ester, a carboxylic acid ester, a C5-C 16the positive electrode active material includes at least one of an alkane, an aromatic hydrocarbon having an electron-withdrawing group and / or an alkyl group, a nitrile, and a ketone, and the electron-withdrawing group includes at least one of a halogen, —NO2, —C≡N, —C≡C, —C≡C, and —OCH3. By filling the polymer layer with this type of organic solvent, direct contact between the positive electrode active material and the electrolyte solvent in the battery can be effectively blocked, thereby avoiding oxidative decomposition of the electrolyte solvent and reducing the risk of the battery being overcharged.

[0028] In some embodiments, the film-forming additive comprises at least one of bis(oxalato)borate, difluoro(oxalato)borate, difluorophosphate, methyl 2,2,2-trifluoroethyl carbonate, tris(pentafluorophenyl)borane, fluoroethylene carbonate, fluoroethylene carbonate, methyl 2,2,2-trifluoroethyl carbonate, and trifluoropropylene carbonate.

[0029] In some embodiments, the sorption additive comprises at least one of a carbonate ester, a phosphate ester, a nitrile, and an ionic liquid.

[0030] In some embodiments, the electrochemical oxidation potential window of the polymer is higher than 4 V. This prevents oxidation reactions from occurring on the positive electrode side under conditions of high cutoff voltage (>4 V) and high rate charging, thereby reducing the risk of overcharging the battery.

[0031] In some embodiments, the swelling degree of the polymer is 5% to 2000%, and optionally 50% to 1500%, which can improve the liquid retention performance of the polymer and prevent direct contact between the positive electrode active material and the electrolyte solvent in the battery, thereby avoiding oxidative decomposition of the electrolyte solvent and reducing the risk of overcharging the battery.

[0032] In some embodiments, the crosslinking density of the polymer is 1% to 100%, and optionally 30% to 70%, which can improve the liquid retention performance of the polymer and prevent direct contact between the positive electrode active material and the electrolyte solvent in the battery, thereby avoiding oxidative decomposition of the electrolyte solvent and reducing the risk of overcharging the battery.

[0033] In some embodiments, the number-average molecular weight of the polymer is 10,000 to 1,000,000, and optionally 50,000 to 600,000, which can improve the liquid absorption and retention performance of the polymer and prevent direct contact between the positive electrode active material and the electrolyte solvent in the battery, thereby avoiding oxidative decomposition of the electrolyte solvent and reducing the risk of overcharging the battery.

[0034] In some embodiments, the polymer comprises the following repeating unit: [ka] R1-R4 each independently include H, an alkyl group, F, Cl, Br, I, C≡N, a phenyl group, a pyrrolyl group, a pyrrolone group, a sulfonic acid group, a sulfonate group, a benzenesulfonate group, a carboxylic acid group, and a carbonate group.

[0035] By filling the polymer with an organic solvent, the polymer's adsorption performance for the organic solvent can be improved, and direct contact between the positive electrode active material and the electrolyte solvent in the battery can be effectively blocked, thereby avoiding oxidative decomposition of the electrolyte solvent and reducing the risk of the battery being overcharged.

[0036] In some embodiments, the repeat unit comprises at least one of the following structural formulas: [ka]

[0037] By filling a polymer of this composition with an organic solvent, the polymer's adsorption performance for the organic solvent can be improved, and direct contact between the positive electrode active material and the electrolyte solvent in the battery can be effectively blocked, thereby avoiding oxidative decomposition of the electrolyte solvent and reducing the risk of the battery being overcharged.

[0038] According to a second aspect of the present application, there is provided a method for manufacturing a positive electrode sheet, the method comprising forming a positive electrode sheet comprising a polymer and an organic solvent, the polymer and the organic solvent being located on at least one side of the positive electrode sheet away from the positive electrode current collector, the organic solvent being located in the polymer, and an electrochemical oxidation reaction potential window of the organic solvent being higher than 4 V.

[0039] This allows the preparation of a positive electrode sheet containing the above polymer and organic solvent, the organic solvent being located within the polymer, and the polymer and organic solvent being located on at least one side of the positive electrode sheet away from the positive electrode current collector. The organic solvent-filled polymer can block direct contact between the positive electrode active material and the electrolyte solvent in the battery, thereby preventing oxidative decomposition of the electrolyte solvent. At the same time, the electrochemical oxidation reaction potential window of the organic solvent is higher than 4 V, i.e., under high cutoff voltage (>4 V) charging conditions, the organic solvent does not undergo oxidation reactions at the positive electrode side, thereby preventing side reactions at the positive electrode side. Furthermore, under high-rate charging, the organic solvent is not easily excited to undergo oxidative decomposition, so additional electrons are not generated and reach the negative electrode side, preventing an abnormal increase in the battery charge capacity and reducing the risk of battery overcharging.

[0040] In some embodiments, the method for forming the positive electrode sheet containing the polymer and the organic solvent includes forming a positive electrode active material layer containing positive electrode active material particles on at least one side of the positive electrode current collector, and forming a polymer layer containing the polymer and the organic solvent on the surface of the positive electrode active material particles. By forming the polymer layer containing the polymer and the organic solvent on the surface of the positive electrode active material particles, the polymer layer can block direct contact between the positive electrode active material and the electrolyte solvent in the battery, thereby avoiding oxidative decomposition of the electrolyte solvent and reducing the risk of the battery being overcharged.

[0041] In some embodiments, the method for forming the positive electrode sheet containing the polymer and the organic solvent includes forming a positive electrode active material layer on at least one side of the positive electrode current collector, and forming a protective layer containing the polymer and the organic solvent on at least one side of the positive electrode active material layer, whereby the protective layer containing the polymer and the organic solvent is formed on the positive electrode active material layer, thereby blocking direct contact between the positive electrode active material and the electrolyte solvent in the battery, thereby avoiding oxidative decomposition of the electrolyte solvent and reducing the risk of the battery being overcharged.

[0042] According to a third aspect of the present application, there is provided a battery including the above positive electrode sheet.

[0043] In some embodiments, the battery includes an electrolyte, the electrolyte includes a primary solvent, and the primary solvent is different from the organic solvent in the positive electrode sheet.

[0044] In some embodiments, the battery includes an electrolyte, and the electrochemical oxidation reaction potential window of the primary solvent is 4 V or less.

[0045] According to a fourth aspect of the present invention, there is provided a power consuming device including the battery described above.

[0046] Additional aspects and advantages of the present application will be set forth in part in the description that follows, and in part will be obvious from the description, or may be learned by practice of the present application. [Brief explanation of the drawings]

[0047] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of the preferred embodiments. The drawings are for the purpose of illustrating the preferred embodiments and should not be considered as limiting the present application. In the drawings, like elements use like reference numerals. The drawings are as follows:

[0048] [Figure 1] 1 is a structural schematic diagram of a positive electrode sheet according to an embodiment of the present application. [Figure 2] FIG. 2 is a structural schematic diagram of a positive electrode sheet according to another embodiment of the present application. [Figure 3] 1 is a structural schematic diagram of a battery according to an embodiment of the present application; [Figure 4] 1 is a structural schematic diagram of a battery module according to an embodiment of the present application; [Figure 5] 1 is a structural schematic diagram of a battery pack according to an embodiment of the present application; [Figure 6] FIG. 6 is an exploded view of FIG. 5. [Figure 7] 1 is a schematic diagram of one embodiment of a power consuming device that uses a battery as a power source.

[0049] 100 positive electrode sheet, 11 positive electrode current collector, 12 positive electrode active material layer, 13 protective layer, 1 secondary battery, 2 battery module, 3 battery pack, 4 upper housing, 5 lower housing. DETAILED DESCRIPTION OF THE INVENTION

[0050] The following describes in detail the embodiments of the technical solution of the present application. The following embodiments are only used to more clearly explain the technical solution of the present application, and are merely examples, which do not limit the protection scope of the present application.

[0051] References to "an embodiment" herein mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present application. Appearances of the term "embodiment" in various places in this specification do not necessarily refer to the same embodiment, nor do they refer to embodiments that are mutually exclusive, independent, or alternative to other embodiments. Those skilled in the art will understand, both explicitly and implicitly, that the embodiments described herein can be combined with other embodiments.

[0052] For the sake of brevity, only a few numerical ranges are specifically disclosed herein. However, any lower limit can be combined with any upper limit to form an unspecified range, any lower limit can be combined with another lower limit to form an unspecified range, and any upper limit can be combined with another upper limit to form an unspecified range. Furthermore, each point or individual numerical value disclosed alone can serve as a lower or upper limit, and can be combined with any other point or individual numerical value, or with other lower or upper limits, to form an unspecified range.

[0053] The term "and / or" in the description of the embodiments of the present application merely describes the relationship between related objects and indicates that three types of relationships can exist. For example, A and / or B can indicate three situations: A exists alone, A and B exist simultaneously, and B exists alone. In this specification, the symbol " / " generally indicates that the related objects before and after it are in an "or" relationship.

[0054] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs, and the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The terms "including" and "having" and their variants in the specification and claims of this application, as well as the description of the drawings above, are intended to be non-exclusive.

[0055] With the technological development and increasing demand for electric vehicles and rechargeable mobile devices, secondary batteries have become a representative of the new energy field, and related research work is also progressing rapidly. As the application fields of power batteries continue to expand, their demand in the market also continues to grow.

[0056] Electrolytes, which function as ion conductors between the positive and negative electrodes of secondary batteries, comprise an electrolyte salt and a solvent. To promote the use of metal anodes, electrolytes compatible with reduction-resistant metal anodes have been developed. However, the oxidation potential window of these electrolytes is poorly compatible with high-voltage positive electrode materials. Under high cutoff voltage (>4V) charging conditions, the electrolyte solvent is easily oxidized at the positive electrode interface, resulting in serious interfacial side reactions. At the same time, during high-rate charging, the space charge effect on the positive electrode is so strong that it stimulates the oxidative decomposition of the solvent. During oxidation of the positive electrode interfacial solvent, the solvent loses electrons, which then travel through an external circuit to the negative electrode, completing a circuit and resulting in an increase in the battery's charge capacity. However, these side reactions are irreversible, and the electrons that reach the negative electrode cannot return to the positive electrode during the battery's discharge process, resulting in an abnormal increase in charge capacity and the risk of overcharging.

[0057] To solve the above problems, conventional techniques have attempted to use oxidation-resistant electrolyte solvents to replace electrolyte solvents with low electrochemical oxidation reaction potential windows. However, because oxidation-resistant electrolytes cannot withstand reduction, side reactions occur on the negative electrode side during the battery charging process, which tends to cause deterioration of the negative electrode, thereby reducing the cycle characteristics of the battery.

[0058] The present application uses a positive electrode sheet containing a polymer and an organic solvent, with the organic solvent located within the polymer. The organic solvent-filled polymer can block direct contact between the positive electrode active material and the electrolyte solvent, thereby preventing oxidative decomposition of the electrolyte solvent. At the same time, the electrochemical oxidation potential window of the organic solvent is higher than 4 V, meaning that under high cutoff voltage (>4 V) charging conditions, the organic solvent does not undergo oxidation reactions at the positive electrode side, thereby preventing side reactions at the positive electrode side. Furthermore, under high-rate charging, the organic solvent is not easily stimulated to undergo oxidative decomposition, so additional electrons are not generated and reach the negative electrode side, preventing an abnormal increase in the battery's charge capacity and reducing the risk of overcharging.

[0059] The batteries disclosed in the embodiments of the present application can be used in various energy storage systems that use batteries as power sources or as energy storage elements. The power consumption devices can be, but are not limited to, mobile phones, tablets, laptops, electric toys, power tools, battery cars, electric vehicles, boats, spacecraft, etc. The electric toys can include stationary or mobile electric toys such as game consoles, electric toy cars, electric toy boats, and electric toy aircraft, and the spacecraft can include airplanes, rockets, space shuttles, spaceships, etc.

[0060] A first aspect of the present application provides a positive electrode sheet, the positive electrode sheet including a positive electrode current collector and including a polymer and an organic solvent on at least one side of the positive electrode sheet away from the positive electrode current collector, the organic solvent being located within the polymer, and the organic solvent having an electrochemical oxidation reaction potential window of greater than 4 V.

[0061] The present application uses a positive electrode sheet containing a polymer and an organic solvent, with the organic solvent located within the polymer and the polymer and organic solvent located on at least one side of the positive electrode sheet away from the positive electrode current collector. The organic solvent-filled polymer can block direct contact between the positive electrode active material and the electrolyte solvent in the battery, thereby preventing oxidative decomposition of the electrolyte solvent. At the same time, the electrochemical oxidation potential window of the organic solvent is higher than 4 V, i.e., under high cutoff voltage (>4 V) charging conditions, the organic solvent does not undergo oxidation reactions at the positive electrode side, thereby preventing side reactions at the positive electrode side. Furthermore, under high-rate charging, the organic solvent is not easily excited to undergo oxidative decomposition, so additional electrons are not generated and reach the negative electrode side, preventing an abnormal increase in the battery's charge capacity and reducing the risk of battery overcharging.

[0062] In this application, the term "electrochemical oxidation potential window" refers to the potential range in which no redox reaction occurs in a voltammetry test. The higher the electrochemical oxidation potential window of an organic solvent, the higher the oxidation potential of the corresponding organic solvent, i.e., the less susceptible the organic solvent is to oxidation. To reduce side reactions of the organic solvent on the positive electrode side, the organic solvents used in this application have electrochemical oxidation potential windows higher than the cutoff voltage during the charging process of the battery. Furthermore, methods for measuring the "electrochemical oxidation potential window of an organic solvent" in this application include cyclic voltammetry and linear sweep voltammetry.

[0063] In the present application, "containing a polymer and an organic solvent on at least one side of the positive electrode sheet remote from the positive electrode current collector" can be understood to mean that when the positive electrode sheet is coated on one side of the positive electrode current collector, the polymer and organic solvent are located on the side of the coating layer remote from the positive electrode current collector, and when the positive electrode sheet is coated on both sides of the positive electrode current collector, the polymer and organic solvent are located on the side of the coating layer on one side or on both sides of the coating layer remote from the positive electrode current collector.

[0064] In some embodiments, referring to FIG. 1 , the positive electrode sheet 100 includes a positive electrode current collector 11 and a positive electrode active material layer 12, the positive electrode active material layer 12 is provided on at least one side of the positive electrode current collector 11, the positive electrode active material layer 12 includes positive electrode active material particles and has a polymer layer on the surface of the positive electrode active material particles, and the polymer layer includes the polymer and the organic solvent.

[0065] In this specification, the phrase "the organic solvent is located within the polymer" means that the polymer absorbs or adsorbs the organic solvent into its molecular network by utilizing its swelling properties.

[0066] The present application provides a polymer layer containing a polymer and an organic solvent on the surface of positive electrode active material particles. This polymer layer can block direct contact between the positive electrode active material and the electrolyte solvent in the battery, thereby preventing oxidative decomposition of the electrolyte solvent and reducing the risk of battery overcharging. At the same time, the electrochemical oxidation potential window of the organic solvent is higher than 4 V, meaning that under high cutoff voltage (>4 V) charging conditions, the organic solvent does not undergo oxidation reactions at the positive electrode, thereby preventing side reactions at the positive electrode. Furthermore, under high-rate charging, the organic solvent is less likely to undergo oxidative decomposition, preventing additional electrons from being generated and reaching the negative electrode, preventing an abnormal increase in the battery's charge capacity and reducing the risk of battery overcharging.

[0067] In some embodiments of the present application, the positive electrode current collector 11 can be a conventional metal foil piece or a composite positive electrode current collector (which may be a composite positive electrode current collector formed by placing a metal material on a polymer substrate.) For example, the positive electrode current collector 11 can be one or more of aluminum foil, nickel foil, stainless steel foil, stainless steel mesh, or carbon-coated aluminum foil.

[0068] In some embodiments of the present application, the specific type of the positive electrode active material particle material is not particularly limited, and active materials known in the art for use in battery positive electrodes can be used, and a person skilled in the art can select the type according to actual needs.

[0069] For example, when the battery is a lithium-ion battery, the positive electrode active material particles may include, but are not limited to, one or more of lithium transition metal oxides, lithium-containing phosphates with an olivine structure, and their respective modified compounds. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their modified compounds. Examples of lithium-containing phosphates with an olivine structure include, but are not limited to, one or more of lithium iron phosphate, lithium iron phosphate and carbon composites, lithium manganese phosphate, lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, lithium manganese iron phosphate and carbon composites, and their modified compounds. All of these materials are commercially available.

[0070] For example, when the battery is a sodium ion battery, the positive electrode active particle material may include at least one of a layered transition metal oxide, a polyanion compound, and a Prussian blue analogue.

[0071] Examples of the layered transition metal oxide include the following.

[0072] Na 1-x Cu h Fe k Mn l M 1 m O 2-y and M 1is one or more of Li, Be, B, Mg, Al, K, Ca, Ti, Co, Ni, Zn, Ga, Sr, Y, Nb, Mo, In, Sn, and Ba; <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である。

[0073] Na 0.67 Mn 0.7 Ni z M 2 0.3-z O2 and M 2 is one or more of Li, Mg, Al, Ca, Ti, Fe, Cu, Zn and Ba, and 0 <z≦0.1である。

[0074] Na a Li b Ni c Mn d Fe e O2 is 0.67 <a≦1、0<b<0.2、0<c<0.3、0.67<d+e<0.8、b+c+d+e=1である。

[0075] Examples of the polyanion compound include the following:

[0076] A 1 f M 3 g (PO4) i O j X 1 3-j and 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, and X 1 is one or more of F, Cl and Br, and 0 <f≦4、0<g≦2、1≦i≦3、0≦j≦2である。

[0077] Na n M 4 PO4X 2 and M 4is one or more of Mn, Fe, Co, Ni, Cu, and Zn, X 2 is one or more of F, Cl, and Br, and 0 < n ≤ 2.

[0078] Na p M 5 q (SO4)3, and M 5 is one or more of Mn, Fe, Co, Ni, Cu, and Zn, 0 < p ≤ 2, 0 < q ≤ 2.

[0079] Na s Mn t Fe 3-t (PO4)2(P2O7), 0 < s ≤ 4, 0 ≤ t ≤ 3, for example, t is 0, 1, 1.5, 2, or 3.

[0080] Examples of the above Prussian blue analogs include, for example, the following.

[0081] A u M 6 v [M 7 (CN)6] w ·xH2O, where A is H + , NH4 + , one or more of alkali metal cations and alkaline earth metal cations, 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 + M Na + K + NH4 + Rb + Cs + Fr + [[ID=6,4]]Be 2+ Mg 2+ Ca 2+ Sr 2+ Ba 2+ and Ra 2+ one or more of, M 6 and M 7are each independently a cation of one or more transition metal elements of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn, and W.

[0082] The modifying compound of each of the above materials may be a material that has been subjected to doping modification and / or surface coating modification.

[0083] The positive electrode active material layer typically further includes at least one of a binder and a conductive agent. The conductive agent is used to improve the conductivity of the positive electrode active material layer, and the binder is used to strongly bond the positive electrode active material and binder to the positive electrode current collector. The present application does not specifically limit the types of conductive agent and binder, and they can be selected according to actual requirements.

[0084] By way of example, the conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, Super P (SP), graphene, and carbon nanofibers.

[0085] By way of example, the binder may include one or more of styrene butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB).

[0086] In some embodiments of the present application, the mass ratio of the positive electrode active material particles to the binder and the conductive agent is (90 to 100):(0 to 5):(0 to 5), for example, (92 to 99):(0 to 5):(0 to 5), (94 to 98):(0 to 5):(0 to 5), (95 to 97):(0 to 5):(0 to 5), (95 to 96):(0 to 5):(0 to 5), (90 to 100):(0. (90-100):(1-4):(0-5), (90-100):(2-3):(0-5), (90-100):(0-5):(0.5-5), (90-100):(0-5):(1-4), (90-100):(0-5):(1-3), (90-100):(0-5):(1-2), (96-99):(0.5-1):(0.5-1), etc. In some embodiments of the present application, the mass ratio of the positive electrode active material particles to the binder and the conductive agent is (95-98.5):(0.5-2):(0.5-2). As a result, a positive electrode paste is formed from the positive electrode active material particles, conductive agent, and binder in the blending ratio of the present invention, thereby improving the conductivity of the positive electrode active material layer and the bonding strength with the positive electrode current collector.

[0087] In some embodiments of the present application, the thickness of the positive electrode active material layer 11 in the positive electrode sheet 100 may be 30 μm to 60 μm, for example, 30 μm to 58 μm, 30 μm to 55 μm, 30 μm to 52 μm, 30 μm to 50 μm, 32 μm to 48 μm, 35 μm to 45 μm, 38 μm to 42 μm, or 40 μm to 42 μm. This allows a positive electrode active material layer of this thickness to improve the energy density of the battery. In another embodiment of the present application, the thickness of the positive electrode active material layer 11 may be 30 μm to 50 μm.

[0088] In some embodiments of the present application, the polymer layer formed on the surface of the positive electrode active material particle may have a thickness of 0.01 μm to 2 μm, for example, 0.01 μm to 1.8 μm, 0.02 μm to 1.6 μm, 0.05 μm to 1.5 μm, 0.08 μm to 1.2 μm, 0.1 μm to 1 μm, 0.1 μm to 0.8 μm, 0.1 μm to 0.6 μm, 0.1 μm to 0.5 μm, 0.1 μm to 0.4 μm, 0.1 μm to 0.34 μm, 0.1 μm to 0.2 μm, etc. In another embodiment of the present application, the polymer layer formed on the surface of the positive electrode active material particle may have a thickness of 0.01 μm to 1 μm. This results in the formation of a polymer layer of this thickness on the surface of the positive electrode active material particles, which not only effectively blocks direct contact between the positive electrode active material and the electrolyte solvent in the battery, but also prevents oxidative decomposition of the electrolyte solvent and reduces the impedance of the positive electrode sheet.

[0089] In some embodiments of the present application, the mass ratio of the polymer to the organic solvent in the polymer layer may be (0.1 to 99):(1 to 99.9), for example, (0.5 to 98):(1 to 99.9), (1 to 97):(1 to 99.9), (5 to 95):(1 to 99.9), (10 to 90):(1 to 99.9), (15 to 85):(1 to 99.9), (20 to 80):(1 to 99.9), (25 to 75):(1 to 99.9), or (30 to 70):(1 to 99.9). ), (40-60):(1-99.9), (50-60):(1-99.9), (0.1-99):(2-99), (0.1-99):(4-97), (0.1-99):(5-95), (0.1-99):(10-90), (0.1-99):(15-85), (0.1-99):(20-80), (0.1-99):(25-75), (0.1-99):(30-70), (0.1-99):(40-60), (0.1-99):(50-60), etc. In another embodiment of the present application, the mass ratio of the polymer to the organic solvent in the polymer layer may be (0.1-15):(85-99.9). As a result, a polymer layer is formed on the surface of the positive electrode active material particles using the polymer and organic solvent in the above proportions, which effectively blocks direct contact between the positive electrode active material and the electrolyte solvent in the battery, avoids oxidative decomposition of the electrolyte solvent, and reduces the risk of the battery being overcharged.

[0090] In some embodiments of the present application, the organic solvent is a carbonate ester, a carboxylic acid ester, a C5-C 16 and at least one of alkanes, aromatic hydrocarbons having electron-withdrawing groups and / or alkyl groups, nitriles, and ketones, wherein the electron-withdrawing groups include at least one of halogen, —NO2, —C≡N, —C≡C, —C≡C, and —OCH3.

[0091] For example, the carbonate ester may include, but is not limited to, at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, dipropyl carbonate, diphenyl carbonate, dibutyl carbonate, and butylene carbonate; the carboxylic acid ester may include, but is not limited to, at least one of propyl butyrate, propyl acetate, isopropyl acetate, ethyl propionate, propyl propionate, butyl propionate, isopropyl propionate, and ethyl butyrate; and the C5-C 16 The alkane in the column indicates an alkane with 5-16 carbon atoms, and includes n-pentane, isopentane, neopentane, n-hexane, isohexane, 3-methylpentane, 2,3-dimethylbutane, 2,2-dimethylbutane, n-heptane, 2-methylhexane, 3-methylhexane, 2,4-dimethylpentane, 2,3-dimethylpentane, 2,2-dimethylpentane, 3,3-dimethylpentane, 3-ethylpentane, 2,2,3-trimethylbutane, n-octane, 2-methylheptane, 3-methylheptane, 4-methylheptane, 2,2-dimethylhexane, 3,3-dimethylhexane, 2,3-dimethylhexane, 2 ,4-dimethylhexane, 2,5-dimethylhexane, 3,4-dimethylhexane, nonane, 2-methyloctane, 3-methyloctane, 4-methyloctane, 3-ethylheptane, 4-ethylheptane, 2,2-dimethylheptane, 2,3-dimethylheptane, n-decane, 2-methylnonane, 3-methylnonane, 4-methylnonane, 3-ethyloctane, 2,3-dimethyldecane, 2,4-dimethyldecane, 2,2,3-trimethylhexane, 2,2,3,3-tetramethylhexane, 4,4-diethylhexane, and 3,4,4-triethylhexane.

[0092] For example, the function of the electron-withdrawing group in the aromatic hydrocarbon having an electron-withdrawing group and / or alkyl group is to improve the antioxidant properties of the organic solvent, and the function of the alkyl group is to lower the melting point of the aromatic hydrocarbon and improve its boiling point and oxidation resistance. The alkyl group may include a C1-C5 alkyl group, and a C1-C5 alkyl group can be understood to mean an alkyl group having 1 to 5 carbon atoms, such as a methyl group (-CH3), an ethyl group (-CH2CH3), an n-propyl group (-CH2CH2CH3), an isopropyl group (-CH(CH3)2), an n-butyl group (-CH2CH2CH2CH 3), tert-butyl group (-C(CH3)3), n-pentyl group (-CH2CH2CH2CH2CH3), etc., and aromatic hydrocarbons having electron-withdrawing groups and / or alkyl groups may include, but are not limited to, at least one of chlorobenzene, bromobenzene, iodobenzene, fluorobenzene, nitrobenzene, cyanobenzene, styrene, phenylacetylene, anisole, toluene, ethylbenzene, propylbenzene, p-chlorotoluene, 3-chlorotoluene, 1,2-dimethyl-3-ethylbenzene, butylbenzene, p-chlorobutylbenzene, amylbenzene, etc.

[0093] By way of example, the nitrile may include, but is not limited to, at least one of acetonitrile, propionitrile, butyronitrile, isobutyronitrile, valeronitrile, 3-methoxypropionitrile, and cyclopentanenitrile, and the ketone may include, but is not limited to, at least one of acetone, methylbutanone, methyl isobutyl ketone, and the like.

[0094] Therefore, by filling the polymer layer with the organic solvent of this type, the direct contact between the positive electrode active material and the electrolyte solvent in the battery can be effectively blocked, thereby avoiding the oxidative decomposition of the electrolyte solvent and reducing the risk of the battery being overcharged. At the same time, the electrochemical oxidation reaction potential window of this organic solvent is higher than 4V, that is, under the condition of high cutoff voltage (>4V) charging, this organic solvent does not cause an oxidation reaction on the positive electrode side, so that no side reaction occurs on the positive electrode side. Furthermore, under high rate charging, this organic solvent is not easily excited to undergo oxidative decomposition, so that additional electrons are not generated and reach the negative electrode side, and the phenomenon of abnormal increase in the charge capacity of the battery does not occur, reducing the risk of battery overcharging.

[0095] In some embodiments of the present application, the electrochemical oxidation reaction potential window of the polymer in the polymer layer is higher than 4 V. This prevents oxidation reactions from occurring on the positive electrode side under conditions of a high cutoff voltage (>4 V) and high-rate charging, thereby reducing the risk of overcharging the battery.

[0096] In this application, the test method for the "electrochemical oxidation potential window of polymers" can refer to the test method for the "electrochemical oxidation potential window of organic solvents." In order to reduce side reactions at the positive electrode, the electrochemical oxidation potential window of the polymers used in this application is higher than the cutoff voltage during the charging process of the battery.

[0097] In some embodiments of the present application, the swelling degree of the polymer is 5% to 2000%, e.g., 10% to 1990%, 50% to 1900%, 70% to 1800%, 100% to 1700%, 150% to 1600%, 200% to 1500%, 300% to 1400%, 400% to 1300%, 500% to 1200%, 600% to 1100%, 700% to 1000%, 800% to 900%, etc. In other embodiments of the present application, the swelling degree of the polymer is 50% to 1500%.

[0098] This can enhance the organic solvent adsorption performance of the polymer, slowing down the migration of the electrolyte solvent into the polymer layer and reducing the risk of the battery being overcharged.

[0099] In the present application, the polymer swelling degree is measured as follows.

[0100] The polymer was rubbed on a glass plate, and a polymer film measuring 1 cm × 1 cm was taken and weighed on a precision balance to obtain the initial mass M1. The polymer film was then added to dimethyl carbonate and immersed for 12 hours. After removal, the mass of the polymer film, M2, was weighed, and the weight gain was M2-M1.

[0101] The polymer swelling degree (C) is calculated by the following formula: C=(M2-M1) / M1×100%.

[0102] In some embodiments of the present application, the crosslink density of the polymer is 1% to 100%, for example, 3% to 99%, 5% to 98%, 7% to 97%, 10% to 96%, 15% to 96%, 20% to 95%, 25% to 90%, 30% to 85%, 35% to 80%, 40% to 75%, 45% to 70%, 50% to 65%, 55% to 60%, etc. In some embodiments of the present application, the crosslink density of the polymer is 30% to 70%. This can improve the liquid absorption and retention performance of the polymer and prevent direct contact between the positive electrode active material and the electrolyte solvent in the battery, thereby preventing oxidative decomposition of the electrolyte solvent and reducing the risk of overcharging the battery.

[0103] In the present application, the "crosslink density of a polymer" is a physical quantity used to indicate the degree of crosslinking of a polymer, i.e., the proportion of crosslinked structural units Nc in a crosslinked chain to all structural units N. The crosslink density can be measured using a nuclear magnetic crosslink density meter, and specifically, in the examples of the present application, it can be measured using an IIC XLDS-15 crosslink density measuring device.

[0104] In some embodiments of the present application, the number average molecular weight of the polymer is 10,000 to 1,000,000, for example, 50,000 to 950,000, 100,000 to 900,000, 150,000 to 850,000, 200,000 to 800,000, 250,000 to 750,000, 300,000 to 700,000, 350,000 to 650,000, 400,000 to 600,000, 450,000 to 550,000, 450,000 to 500,000, etc. In another embodiment of the present application, the number average molecular weight of the polymer is 50,000 to 600,000.

[0105] In the present application, the "number average molecular weight of the polymer" can be measured using gel permeation chromatography.

[0106] In some embodiments of the present application, the polymer comprises the following repeating units: [ka]

[0107] R1-R4 each independently include H, an alkyl group, F, Cl, Br, I, C≡N, a phenyl group, a pyrrolyl group, a pyrrolone group, a sulfonic acid group, a sulfonate group, a benzenesulfonate group, a carboxylic acid group, and a carbonate group. As used herein, an "alkyl group" refers to a bicarbonate group formed by removing one hydrogen atom from an alkane molecule, such as a methyl group (-CH), an ethyl group (-CHCH), an n-propyl group (-CHCHCH), an isopropyl group (-CH(CH)), an n-butyl group (-CHCHCHCHCH), a tert-butyl group (-C(CH)), an n-pentyl group (-CHCHCHCHCHCH), an isopentyl group (-CH(CH)CHCHCHCH), a 2-methylbutyl group (-CHCH(CH)CHCHCH), an n-hexyl group (CH(CH)CH-), a 2-methylpentyl group (-CHCHCHCHCH(CH)). A "sulfonate group" may include a sodium sulfonate group. A "benzenesulfonate group" may include a sodium benzenesulfonate group.

[0108] In one example, the repeat unit comprises at least one of the following structural formulas: [ka]

[0109] In this way, by filling the polymer layer with the organic solvent, direct contact between the positive electrode active material and the electrolyte solvent in the battery can be effectively blocked, thereby avoiding oxidative decomposition of the electrolyte solvent and reducing the risk of the battery being overcharged.

[0110] In some embodiments of the present application, the polymer layer may further include an electrolyte salt, which can improve the ionic conductivity of the polymer layer.

[0111] In this application, when the battery is a lithium-ion battery, the electrolyte salt may be selected from one or more of lithium hexafluorophosphate (LiPF), lithium tetrafluoroborate (LiBF), lithium perchlorate (LiClO), lithium hexafluoroarsenate (LiAsF), lithium bisfluorosulfonylimide (LiFSI), lithium bistrifluoromethanesulfonylimide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalatoborate (LiDFOB), lithium bisoxalatoborate (LiBOB), lithium difluorophosphate (LiPOF), lithium difluorobisoxalatophosphate (LiDFOP), and lithium tetrafluorooxalatophosphate (LiTFOP).

[0112] When the battery is a sodium ion battery, by way of example, the electrolyte sodium salt may include at least one of sodium hexafluorophosphate, sodium difluoro(oxalato)borate, sodium tetrafluoroborate, sodium bis(oxalato)borate, sodium perchlorate, sodium hexafluoroarsenate, sodium bisfluorosulfonylimide, sodium trifluoromethanesulfonate, and sodium bis(trifluoromethanesulfonyl)imide.

[0113] In some embodiments of the present application, the concentration of the electrolyte salt relative to the total amount of the organic solvent and the electrolyte salt may be 0.1 mol / L to 10 mol / L, for example, 0.5 mol / L to 9.5 mol / L, 1 mol / L to 9 mol / L, 1.5 mol / L to 8.5 mol / L, 2 mol / L to 8 mol / L, 2.5 mol / L to 7.5 mol / L, 3 mol / L to 7 mol / L, 3.5 mol / L to 6.5 mol / L, 4 mol / L to 6 mol / L, 4.5 mol / L to 5.5 mol / L, 4.8 mol / L to 5 mol / L, etc. In another embodiment of the present application, the concentration of the electrolyte salt relative to the total amount of the organic solvent and the electrolyte salt may be 0.5 mol / L to 5 mol / L. This allows the addition of electrolyte salt at the above concentration to the polymer layer to improve the ionic conductivity of the polymer layer.

[0114] In some embodiments of the present application, the polymer layer further comprises at least one of a film-forming additive and an adsorption additive, wherein the film-forming additive has an electrochemical oxidation reaction potential window of 4 V or less, and the adsorption additive has an electrochemical oxidation reaction potential window higher than 4 V. By using a film-forming additive with an electrochemical oxidation reaction potential window of 4 V or less, the film-forming additive is oxidatively decomposed on the positive electrode side under high cutoff voltage (>4 V) charging conditions, forming a protective film on the surface of the positive electrode active material particles. This protective film further blocks direct contact between the positive electrode active material and the electrolyte solvent in the battery, preventing oxidative decomposition of the electrolyte solvent and reducing the risk of battery overcharging. The adsorption additive can be adsorbed on the surface of the positive electrode active material, suppressing changes in the interfacial structure of the positive electrode active material and improving the cycle stability of the positive electrode sheet. Furthermore, the present application uses an adsorption additive with an electrochemical oxidation reaction potential window higher than 4 V, which reduces the oxidation reaction of the adsorption additive on the positive electrode side and reducing the risk of battery overcharging.

[0115] In this application, the test method for the "electrochemical oxidation reaction potential window of film-forming additives and adsorption additives" can refer to the test method for the "electrochemical oxidation reaction potential window of organic solvents." In order to reduce side reactions on the positive electrode side, the adsorption additive used in this application has an electrochemical oxidation reaction potential window higher than the cut-off voltage during the charging process of the battery.

[0116] In some embodiments of the present application, the mass ratio of the polymer to the film-forming additive and the adsorption additive in the polymer layer may be (10-100):(0-90):(0-90), for example, (20-90):(0-90):(0-90), (30-80):(0-90):(0-90), (40-70):(0-90):(0-90), (50-60):(0-90):(0-90), (10-100):(10-80):(0-90), (10-100):(20-70):(0-90), ( In another embodiment of the present application, the mass ratio of the polymer to the film-forming additive and the adsorption additive in the polymer layer is (30-80):(20-70):(20-70). By using a polymer layer with the above composition, the cycle stability of the positive electrode sheet can be improved, and side reactions on the positive electrode side can be reduced, reducing the risk of the battery being overcharged.

[0117] As an example, the film-forming additive includes, but is not limited to, at least one of bis(oxalato)borate, difluoro(oxalato)borate, difluorophosphate, methyl 2,2,2-trifluoroethyl carbonate, tris(pentafluorophenyl)borane, fluoroethylene carbonate, fluoroethylene carbonate, methyl 2,2,2-trifluoroethyl carbonate, and trifluoropropylene carbonate. For example, when the battery is a lithium ion battery, the bis(oxalato)borate, difluoro(oxalato)borate, and difluorophosphate are used in the form of the corresponding lithium salt, i.e., lithium bisoxalatoborate, lithium difluorooxalatoborate, and lithium difluorophosphate. When the battery is a sodium ion battery, the bis(oxalato)borate, difluoro(oxalato)borate, and difluorophosphate are used in the form of the corresponding sodium salt, i.e., bis(oxalato). g) Sodium borate, sodium difluoro(oxalato)borate, and sodium difluorophosphate are used, and the adsorption additives include, but are not limited to, at least one of carbonate esters, phosphate esters, nitriles, and ionic liquids. For example, carbonate esters include, but are not limited to, at least one of methyl ethyl carbonate, ethylene carbonate, and propylene carbonate. Phosphate esters include, but are not limited to, at least one of dimethyl phenylphosphonate and dimethyl benzylphosphonate. Nitriles include, but are not limited to, at least one of acetonitrile and succinonitrile. Ionic liquids include, but are not limited to, 1-butyl-3-methylimidazolium hexafluorophosphate, for example, lithium 1-butyl-3-methylimidazolium hexafluorophosphate or sodium 1-butyl-3-methylimidazolium hexafluorophosphate.

[0118] In some embodiments of the present application, referring to FIG. 2 , the positive electrode sheet 100 of the present application includes a positive electrode current collector 11, a positive electrode active material layer 12, and a protective layer 13, the positive electrode active material layer 12 is provided on at least one side of the positive electrode current collector 11, the protective layer 13 is provided on at least one side of the positive electrode active material layer 12, and the protective layer 12 includes the polymer and the organic solvent.

[0119] Thus, a protective layer 13 containing a polymer and an organic solvent is formed on the positive electrode active material layer 12. This protective layer 13 prevents direct contact between the positive electrode active material and the electrolyte solvent in the battery, thereby preventing oxidative decomposition of the electrolyte solvent and reducing the risk of overcharging the battery. At the same time, the electrochemical oxidation potential window of the organic solvent is higher than 4 V, meaning that under high cutoff voltage (>4 V) charging conditions, the organic solvent does not undergo oxidation reactions at the positive electrode, thereby preventing side reactions at the positive electrode. Furthermore, under high-rate charging, the organic solvent is not easily stimulated to undergo oxidative decomposition, preventing additional electrons from being generated and reaching the negative electrode, preventing an abnormal increase in the battery's charge capacity and reducing the risk of overcharging the battery.

[0120] In some embodiments of the present application, the thickness of the protective layer 13 may be 0.1 μm to 40 μm, for example, 0.5 μm to 40 μm, 1 μm to 38 μm, 2 μm to 35 μm, 3 μm to 32 μm, 4 μm to 30 μm, 5 μm to 28 μm, 6 μm to 25 μm, 7 μm to 23 μm, 8 μm to 20 μm, 9 μm to 18 μm, 10 μm to 16 μm, 12 μm to 15 μm, etc. In other embodiments of the present application, the thickness of the protective layer 13 may be 1 μm to 20 μm, or even 1 μm to 10 μm. This forms the protective layer 13 of this thickness on the surface of the positive electrode active material layer 12, which not only prevents direct contact between the positive electrode active material and the electrolyte solvent in the battery but also prevents oxidative decomposition of the electrolyte solvent and reduces the impedance of the positive electrode sheet.

[0121] In some embodiments of the present application, the mass ratio of the polymer to the organic solvent in the protective layer 13 may be (0.1 to 99):(1 to 99.9), for example, (0.5 to 98):(1 to 99.9), (1 to 97):(1 to 99.9), (5 to 95):(1 to 99.9), (10 to 90):(1 to 99.9), (15 to 85):(1 to 99.9), (20 to 80):(1 to 99.9), (25 to 75):(1 to 99.9), or (30 to 70):(1 to 99.9). , (40-60):(1-99.9), (50-60):(1-99.9), (0.1-99):(2-99), (0.1-99):(4-97), (0.1-99):(5-95), (0.1-99):(10-90), (0.1-99):(15-85), (0.1-99):(20-80), (0.1-99):(25-75), (0.1-99):(30-70), (0.1-99):(40-60), (0.1-99):(50-60), etc. In another embodiment of the present application, the mass ratio of the polymer to the organic solvent in the protective layer 13 may be (0.1-15):(85-99.9). This effectively blocks direct contact between the positive electrode active material and the electrolyte solvent in the battery, avoiding oxidative decomposition of the electrolyte solvent and reducing the risk of the battery being overcharged.

[0122] In some embodiments of the present application, the protective layer 13 may further include an electrolyte salt, which can improve the ionic conductivity of the protective layer.

[0123] In some embodiments of the present application, the concentration of the electrolyte salt in the protective layer 13 relative to the total amount of the organic solvent and the electrolyte salt is 0.1 mol / L to 10 mol / L, and may be, for example, 0.5 mol / L to 9.5 mol / L, 1 mol / L to 9 mol / L, 1.5 mol / L to 8.5 mol / L, 2 mol / L to 8 mol / L, 2.5 mol / L to 7.5 mol / L, 3 mol / L to 7 mol / L, 3.5 mol / L to 6.5 mol / L, 4 mol / L to 6 mol / L, 4.5 mol / L to 5.5 mol / L, or 4.8 mol / L to 5 mol / L. In another embodiment of the present application, the concentration of the electrolyte salt relative to the total amount of the organic solvent and the electrolyte salt may be 0.5 mol / L to 5 mol / L. By adding an electrolyte salt of the above concentration to the protective layer, the ionic conductivity of the protective layer can be improved.

[0124] In some embodiments of the present application, the protective layer 13 further includes at least one of a film-forming additive and an adsorption additive, which can improve the cycle stability of the positive electrode sheet.

[0125] In some embodiments of the present application, the mass ratio of the polymer to the film-forming additive and the sorption additive in the protective layer 13 is (10-100):(0-90):(0-90), for example, (20-90):(0-90):(0-90), (30-80):(0-90):(0-90), (40-70):(0-90):(0-90), (50-60):(0-90):(0-90), (10-100):(10-80):(0-90), (10-100):(20-70):(0-90), (10 100):(30-60):(0-90), (10-100):(40-50):(0-90), (10-100):(0-90):(10-80), (10-100):(0-90):(20-70), (10-100):(0-90):(30-60), (10-100):(0-90):(40-50), etc. In another embodiment of the present application, the mass ratio of the polymer to the film-forming additive and the adsorption additive in the protective layer 13 is (30-80):(20-70):(20-70). By using a protective layer with the above composition, the cycle stability of the positive electrode sheet can be improved, and side reactions on the positive electrode side can be reduced, reducing the risk of the battery being overcharged.

[0126] In the present application, the compositions and mixing ratios of the positive electrode active material particles, binder, and conductive agent in the positive electrode active material layer 12 in FIG. 2 , and the compositions of the organic solvent, polymer, electrolyte salt, adsorption additive, and film-forming additive in the protective layer 13 are all as described above, and therefore will not be described again here.

[0127] In some embodiments of the present application, the protective layer 13 of Fig. 2 can be formed on the positive electrode active material layer 12 of Fig. 1, i.e., a polymer layer containing a polymer and an organic solvent is formed on the surface of the positive electrode active material particles in the positive electrode active material layer 12, and then the protective layer 13 containing a polymer and an organic solvent is formed on the positive electrode active material layer 12. In this way, the protective layer 13 on the surface of the positive electrode sheet and the polymer layer on the surface of the positive electrode active material particles can both block direct contact between the positive electrode active material and the electrolyte solvent in the battery, preventing oxidative decomposition of the electrolyte solvent and reducing the risk of the battery being overcharged.

[0128] According to a second aspect of the present application, there is provided a method for manufacturing a positive electrode sheet, the method comprising forming a positive electrode sheet comprising a polymer and an organic solvent, the polymer and the organic solvent being located on at least one side of the positive electrode sheet away from the positive electrode current collector, the organic solvent being located in the polymer, and an electrochemical oxidation reaction potential window of the organic solvent being higher than 4 V.

[0129] This allows the preparation of a positive electrode sheet containing the above polymer and organic solvent, the organic solvent being located within the polymer, and the polymer and organic solvent being located on at least one side of the positive electrode sheet away from the positive electrode current collector. The organic solvent-filled polymer can block direct contact between the positive electrode active material and the electrolyte solvent in the battery, thereby preventing oxidative decomposition of the electrolyte solvent. At the same time, the electrochemical oxidation reaction potential window of the organic solvent is higher than 4 V, i.e., under high cutoff voltage (>4 V) charging conditions, the organic solvent does not undergo oxidation reactions at the positive electrode side, thereby preventing side reactions at the positive electrode side. Furthermore, under high-rate charging, the organic solvent is not easily excited to undergo oxidative decomposition, so additional electrons are not generated and reach the negative electrode side, preventing an abnormal increase in the battery charge capacity and reducing the risk of battery overcharging.

[0130] In some embodiments of the present application, the method for manufacturing the positive electrode sheet may include forming a positive electrode active material layer containing positive electrode active material particles on at least one side of the positive electrode current collector, and forming a polymer layer containing the polymer and the organic solvent on surfaces of the positive electrode active material particles.

[0131] For example, a polymer and positive electrode active material particles are mixed in advance to coat the surfaces of the positive electrode active material particles with the polymer. The coated positive electrode active material particles are then mixed with a conductive agent, a binder, and a solvent such as NMP (N-methylpyrrolidone), or the polymer, positive electrode active material particles, a conductive agent, a binder, and a solvent such as NMP (N-methylpyrrolidone) are directly mixed. The positive electrode paste is then applied to the positive electrode current collector, followed by roller coating and drying to remove the NMP solvent. Finally, an organic solvent is applied to the positive electrode sheet by means of immersion, spray coating, dispenser coating, or the like, so that the organic solvent penetrates into the polymer and forms a polymer layer on the surfaces of the positive electrode active material particles. The electrolyte salt, adsorption additive, and film-forming additive are added to the organic solvent to be incorporated into the polymer layer.

[0132] As a result, a polymer layer containing a polymer and an organic solvent is formed on the surface of the positive electrode active material particles, and the polymer layer can block direct contact between the positive electrode active material and the electrolyte solvent in the battery, thereby avoiding oxidative decomposition of the electrolyte solvent and reducing the risk of the battery being overcharged.

[0133] In some embodiments of the present application, the method for manufacturing the positive electrode sheet further includes forming a positive electrode active material layer on at least one side of the positive electrode current collector, and forming a protective layer containing a polymer and the organic solvent on at least one side of the positive electrode active material layer.

[0134] For example, a positive electrode paste prepared by mixing positive electrode active material particles, a conductive agent, a binder, and a solvent (N-methylpyrrolidone (NMP)) is applied to the positive electrode current collector. A mixed solution containing an organic solvent and a polymer is then applied to the positive electrode paste layer, and the NMP solvent and organic solvent are removed by roller coating and drying. Alternatively, a positive electrode paste prepared by mixing positive electrode active material particles, a conductive agent, a binder, and a solvent (N-methylpyrrolidone (NMP)) is applied to the positive electrode current collector, and the NMP solvent is removed by roller coating and drying to form a positive electrode active material layer on the positive electrode current collector. A mixed solution containing an organic solvent and a polymer is then applied to the positive electrode active material layer, and the organic solvent is removed by roller coating and drying to form a positive electrode active material layer and a polymer layer, in that order, on the surface of the positive electrode current collector. Finally, an organic solvent is applied to the positive electrode sheet by immersion, spray coating, dispenser coating, or other methods. The organic solvent penetrates into the polymer layer to form a protective layer, and the electrolyte salt, adsorption additive, and film-forming additive are incorporated into the organic solvent to form the protective layer.

[0135] As a result, a protective layer containing a polymer and an organic solvent is formed on the positive electrode active material layer, and the protective layer can block direct contact between the positive electrode active material and the electrolyte solvent in the battery, thereby avoiding oxidative decomposition of the electrolyte solvent and reducing the risk of the battery being overcharged.

[0136] According to a third aspect of the present application, there is provided a battery including the positive electrode sheet of the first aspect or a positive electrode sheet obtained using the method of the second aspect.

[0137] The battery refers to a battery that can be continuously used by activating the active material through a method of discharging and then charging.

[0138] The battery according to the present application may be a lithium ion battery or a sodium ion battery.

[0139] Generally, a battery includes a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte. During the charge and discharge process, active ions are inserted and removed between the positive and negative electrode sheets. The separator is placed between the positive and negative electrode sheets to provide insulation. The electrolyte conducts ions between the positive and negative electrode sheets.

[0140] [Negative electrode sheet] In a battery, the negative electrode sheet generally includes a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector and including a negative electrode active material.

[0141] The negative electrode sheet may include only the negative electrode positive electrode current collector, i.e., may not include a negative electrode active material. The negative electrode sheet may include a metal phase pre-deposited on the negative electrode positive electrode current collector. The negative electrode positive electrode current collector may be made of a material such as a general metal foil, a carbon-coated metal foil, or a porous metal plate. For example, the negative electrode positive electrode current collector may be made of copper foil or aluminum foil.

[0142] The specific type of the negative electrode active material is not particularly limited, and active materials known in the art for use in negative electrodes of secondary batteries may be used, and those skilled in the art may select a material according to actual needs. For example, the negative electrode active material may include, but is not limited to, one or more of lithium metal, sodium metal, a carbon material, an alloy material, a transition metal oxide and / or sulfide, a phosphorus-based material, and a titanate material. Specifically, the carbon material may include one or more of hard carbon, soft carbon, amorphous carbon, and a nanostructured carbon material. The alloy material may include an alloy material formed from one or more of Si, Ge, Sn, Pb, and Sb. The general formula of the transition metal oxide and sulfide is M. x N y wherein M includes one or more of Fe, Co, Ni, Mn, Sn, Mo, Sb, and V, N includes O or S, the phosphorus-based material may include one or more of red phosphorus, white phosphorus, and black phosphorus, and the titanate material may be Na2Ti3O7, Na2Ti6O 13 , Na4Ti5O12 , Li4Ti5O 12 , NaTi2(PO4)3. All of these materials are commercially available.

[0143] The negative electrode active material layer generally optionally further includes a binder and a conductive agent, where the conductive agent is used to improve the conductivity of the negative electrode active material layer and the binder is used to strongly adhere the negative electrode active material and binder to the negative electrode current collector. The present application does not specifically limit the types of the conductive agent and binder, and they can be selected according to actual requirements.

[0144] By way of example, the conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0145] By way of example, the binder may include one or more of styrene butadiene rubber (SBR), styrene-butadiene block copolymers (SBCs), water-based acrylic resins, and carboxymethyl cellulose (CMC).

[0146] The negative electrode active material layer may optionally further contain a thickener such as carboxymethyl cellulose (CMC), but the present application is not limited thereto, and other materials that can be used as a thickener for the negative electrode sheet of a secondary battery may also be used.

[0147] [Separator] The above separator is not particularly limited in the present application, and any known porous structure separator having good electrical, chemical and mechanical stability can be selected according to actual needs, such as a single-layer or multi-layer film containing one or more of glass fiber, nonwoven fabric, polyethylene, polypropylene and polyvinylidene fluoride.

[0148] [Electrolyte] The electrolyte serves to conduct ions between the positive electrode sheet and the negative electrode sheet. The electrolyte used in the battery of the present application includes a main solvent, and the main solvent is different from the organic solvent in the positive electrode sheet.

[0149] In some embodiments of the present application, the electrochemical oxidation reaction potential window of the main solvent is 4 V or less. As a result, an electrolyte having this composition is less likely to cause side reactions on the negative electrode side during the charging process of the battery, which would otherwise cause deterioration of the negative electrode, thereby improving the cycle characteristics of the battery.

[0150] In the present application, the test method for the "potential window of electrochemical oxidation reaction of a main solvent" can be referred to the test method for the "potential window of electrochemical oxidation reaction of an organic solvent" described above.

[0151] As an example, the primary solvent may include an ether and / or a fluoroether, such as at least one of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether, crown ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, methyl nonafluorobutyl ether, and octafluoropentyl-tetrafluoroethyl ether.

[0152] For example, the electrolyte solution used in the battery of the present application further includes an electrolyte salt, which is the same as described above, and therefore will not be described here.

[0153] The embodiment of the present application does not particularly limit the shape of the battery, and the battery may be cylindrical, rectangular, or any other shape. Figure 3 shows a secondary battery 1 having a rectangular structure as an example.

[0154] In some embodiments, the secondary battery can include a housing material, which is used to encapsulate the positive electrode sheet, the negative electrode sheet, and the electrolyte.

[0155] In some embodiments, the exterior material may include a housing and a cover plate. The housing may include a bottom plate and a side plate connected to the bottom plate, and a storage cavity surrounded by the bottom plate and the side plate is formed. The housing has an opening communicating with the storage cavity, and the cover plate can cover the opening to seal the storage cavity.

[0156] The positive electrode sheet, the negative electrode sheet, and the separator can be wound or stacked to form an electrode assembly. The electrode assembly is sealed in the cavity. The electrolyte can be an electrolytic solution, which is impregnated in the electrode assembly. The number of electrode assemblies included in a sodium ion battery can be one or more, and can be adjusted as needed.

[0157] In some embodiments, the battery's exterior may be a hard case, such as a hard plastic case, an aluminum case, or a steel case.

[0158] The exterior material of the battery may be a soft pack such as a pouch-type soft pack, etc. The material of the soft pack may include one or more of plastics such as polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS), etc.

[0159] In some embodiments, the batteries can be assembled into a battery module, and the number of batteries included in the battery module can be multiple, and the specific number can be adjusted depending on the application and capacity of the battery module.

[0160] FIG. 4 shows an example of a battery module 2. Referring to FIG. 4, in the battery module 2, a plurality of batteries 1 can be arranged in order along the length of the battery module 2. Of course, any other arrangement may be used. The plurality of batteries 1 can also be fixed by fasteners.

[0161] The battery module 2 may further include an outer case having a storage space for storing a plurality of batteries 1. In some embodiments, the battery modules can be further assembled into a battery pack, and the number of battery modules included in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0162] 5 and 6 show an example of a battery pack 3. Referring to FIGS. 5 and 6, the battery pack 3 may include a battery case and a plurality of battery modules 2 installed in the battery case. The battery case includes an upper housing 4 and a lower housing 5, and the upper housing 4 can be fitted over the lower housing 5 to form a sealed space for accommodating the battery modules 2. The plurality of battery modules 2 may be arranged in the battery case in any manner.

[0163] [Power consumption equipment] The present application further provides a power consuming device including at least one of a battery, a battery module, and a battery pack. The battery, battery module, or battery pack may be used as a power source for the power consuming device or as an energy storage element for the power consuming device. The power consuming device may be, but is not limited to, a mobile device (e.g., a mobile phone, a laptop), an electric vehicle (e.g., a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck), a train, a ship, a satellite, or an energy storage system.

[0164] The power consumption device can select a battery, a battery module or a battery pack according to its usage requirements.

[0165] 7 shows an example of a power consuming device, including a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements for the battery of the power consuming device, a battery pack or battery module can be used.

[0166] Other examples of power consuming devices may include mobile phones, tablet computers, and laptops, which are generally required to be lightweight and thin and can use batteries as their power source.

[0167] In order to clarify the technical problems, technical solutions, and beneficial effects solved by the embodiments of the present application, the present application will be described in more detail below with reference to the embodiments and drawings. Obviously, the described embodiments are only some of the embodiments of the present application, and not all of the embodiments. The following description of at least one exemplary embodiment is for illustrative purposes only and does not limit the present application and its applications. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without any creative effort fall within the scope of protection of the present application.

[0168] Example 1 1. Manufacturing of positive electrode sheets Cathode active material particles LiNi 0.8 Co 0.1 Mn 0.1 O2 and polyacrylonitrile were mixed in advance, and the polymer was coated on the surface of the positive electrode active material particles. The coated positive electrode active material particles were then uniformly mixed with the conductive carbon black, the binder polyvinylidene fluoride, and the solvent NMP to obtain a positive electrode paste (positive electrode active material particles LiNi 0.8 Co 0.1 Mn 0.1The mass ratio of O2 to polyacrylonitrile, conductive carbon black, and binder polyvinylidene fluoride was 97.5:0.5:1:1, and the solids content of the positive electrode paste was 60%. The positive electrode paste was applied to the upper and lower surfaces of a carbon-coated aluminum foil positive electrode current collector, followed by roller coating and drying to remove the NMP solvent, forming a 40 μm thick positive electrode active material layer on the copper foil. Finally, the resulting polar sheet was immersed in a mixture containing electrolyte salt, organic solvent, adsorption additive, and film-forming additive. The organic solvent, adsorption additive, and film-forming additive penetrated into the polymer on the surface of the positive electrode active material particles to form a polymer layer, resulting in a positive electrode sheet. The composition and content of the polymer, organic solvent, adsorption additive, and film-forming additive are as shown in Table 1.

[0169] 2. Manufacturing of negative electrode sheets Graphite and the binder sodium carboxymethyl cellulose are added to water in a mass ratio of 4:1.6 and stirred to form a uniform negative electrode paste. The negative electrode paste is applied to the top and bottom surfaces of copper foil, which is then transferred to a vacuum oven to dry completely and then punched out to obtain a negative electrode sheet.

[0170] 3. Electrolyte production In a glove box under an argon atmosphere (HO<0.1 ppm, O<0.1 ppm), lithium bisfluorosulfonylimide (LiFSI) is dissolved in a mixed solvent of organic solvents ethylene glycol dimethyl ether (DME) and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, and the solution is stirred to obtain an electrolyte solution with a concentration of 4 mol / L.

[0171] 4. Separator A polypropylene film is used as the separator.

[0172] 5. Secondary battery manufacturing The positive electrode sheet, separator, and negative electrode sheet are stacked in this order, with the separator between the positive and negative electrode sheets to separate them, and then wound up to obtain an electrode assembly. The electrode assembly is placed in a housing, and the above-prepared electrolyte is injected into the dried lithium-ion battery, which is then vacuum-sealed, left to stand, chemically formed, and shaped to obtain a lithium-ion battery.

[0173] The lithium ion batteries of Examples 2 to 42 were manufactured in the same manner as in Example 1, except that the compositions of the positive electrode sheets were different, as shown in Table 1.

[0174] [Table 1A] [Table 1B] [Table 1C] [Table 1D] [Table 1E] [Table 1F] [Table 1G] [Table 1H] [Table 1I]

[0175] Example 43 The difference from Example 1 is the method for producing the positive electrode sheet, but the other steps are the same as those of Example 1.

[0176] The method for producing the positive electrode sheet includes the following.

[0177] Cathode active material particles LiNi 0.8 Co 0.1 Mn 0.1 O2, conductive carbon black, binder polyvinylidene fluoride, and solvent NMP were uniformly mixed to obtain a positive electrode paste (positive electrode active material particles LiNi 0.8 Co 0.1 Mn 0.1 The mass ratio of O2 to the conductive agent carbon black and the binder polyvinylidene fluoride was 98:1:1, and the solids content of the positive electrode paste was 60%. The positive electrode paste was then applied to the upper and lower surfaces of a carbon-coated aluminum foil positive electrode current collector. A mixture of an organic solvent and a polymer was then applied to the positive electrode paste layer, followed by roller coating and drying to remove the NMP solvent and the organic solvent. A positive electrode active material layer (40 μm thick) and a polymer layer were then sequentially formed on the surface of the positive electrode current collector. Finally, the resulting polar sheet was immersed in a mixture containing an electrolyte salt, an organic solvent, an adsorption additive, and a film-forming additive. The electrolyte salt, organic solvent, adsorption additive, and film-forming additive penetrated into the polymer layer on the surface of the positive electrode active material layer to form a protective layer, resulting in a positive electrode sheet. The composition and content of the polymer, organic solvent, adsorption additive, and film-forming additive are as shown in Table 2.

[0178] The lithium ion batteries of Examples 44 to 83 were manufactured in the same manner as in Example 43, except that the compositions of the positive electrode sheets were different, as shown in Table 2.

[0179] [Table 2A] [Table 2B] [Table 2C] [Table 2D] [Table 2E] [Table 2F] [Table 2G] [Table 2H] [Table 2I]

[0180] Comparative Example

[0181] The difference from Example 1 is the method for producing the positive electrode sheet, but the other steps are the same as those of Example 1.

[0182] The method for producing the positive electrode sheet includes the following.

[0183] Cathode active material particles LiNi 0.8 Co 0.1 Mn 0.1 O2, conductive carbon black, binder polyvinylidene fluoride, and solvent NMP were uniformly mixed to obtain a positive electrode paste (positive electrode active material particles LiNi 0.8 Co 0.1 Mn 0.1 The mass ratio of O2 to the conductive agent carbon black and the binder polyvinylidene fluoride is 98:1:1, and the solid content of the positive electrode paste is 60%. The positive electrode paste is applied to the top and bottom surfaces of the carbon-coated aluminum foil positive electrode current collector, and the NMP solvent is removed through roller coating and drying. A positive electrode active material layer (40 μm thick) is formed on the surface of the positive electrode current collector, and a positive electrode sheet is obtained.

[0184] The changes in charge / discharge coulombic efficiency of the batteries obtained in Examples 1 to 83 and Comparative Example were characterized and evaluated. The results are shown in Table 3.

[0185] Test for change in charge / discharge coulombic efficiency: A charge / discharge test was performed on the battery, in which a constant current charge was performed at 2C, with a charge cutoff voltage of 4.3V, followed by a constant current discharge at 1C, with a discharge cutoff voltage of 2.8V. Then, n cycles of 2C constant current charge and 1C constant current discharge were performed, and the charge specific capacity C0 of the nth cycle and the discharge specific capacity C1 of the nth cycle were recorded.

[0186] The formula for calculating coulombic efficiency (CE) is CE = discharge specific capacity C1 / charge specific capacity C0 × 100%.

[0187] [Table 3A] [Table 3B] [Table 3C]

[0188] Note: CE50%@15 cycles is understood to mean that the coulombic efficiency of the battery is 50% after 15 cycles.

[0189] As can be seen from Table 3, the Coulombic efficiency after 15 cycles of the battery in the comparative example was 50%, and the Coulombic efficiency of the batteries in Examples 1 to 83 was significantly higher than that of the comparative example. This is because in the positive electrode sheet of the present application, a polymer layer containing a polymer and an organic solvent with an electrochemical oxidation reaction potential window higher than 4 V is formed on the surface of the positive electrode active material particles, so that the organic solvent is absorbed or adsorbed into the polymer, or a protective layer containing a polymer and an organic solvent with an electrochemical oxidation reaction potential window higher than 4 V is formed on the surface of the active material of the positive electrode sheet, which can improve the Coulombic efficiency of the battery and thereby reduce the risk of overcharging the battery.

[0190] In the description of this specification, the use of terms such as "one embodiment," "some embodiments," "for example," "specific examples," or "several examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the exemplary descriptions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the described specific features, structures, materials, or characteristics may be combined in an appropriate manner in any one or more embodiments or examples. Furthermore, unless mutually inconsistent, those skilled in the art may combine and combine different embodiments or examples and features of different embodiments or examples described herein.

[0191] Although the embodiments of the present application have been shown and described above, it should be understood that the above embodiments are illustrative and should not be construed as limiting the present application, and that those skilled in the art may make changes, modifications, substitutions and variations to the above embodiments within the scope of the present application. [Explanation of symbols]

[0192] 100 positive electrode sheets, 11 Positive electrode current collector 12 Cathode active material layer 13 Protective layer 1 Secondary battery 2 Battery Module 3 Battery pack 4 Upper case 5 Lower housing

Claims

1. A positive electrode sheet including a positive electrode current collector, A positive electrode sheet comprising a polymer and an organic solvent on at least one side of the positive electrode sheet away from the positive electrode current collector, the organic solvent being located within the polymer, and the electrochemical oxidation reaction potential window of the organic solvent being higher than 4 V.

2. a positive electrode active material layer, 2. The positive electrode sheet according to claim 1, wherein the positive electrode active material layer is provided on at least one side of the positive electrode current collector, the positive electrode active material layer contains positive electrode active material particles, and has a polymer layer on surfaces of the positive electrode active material particles, the polymer layer containing the polymer and the organic solvent.

3. The positive electrode sheet according to claim 2 , wherein the positive electrode active material layer further comprises at least one of a binder and a conductive agent.

4. 4. The positive electrode sheet according to claim 3, wherein the mass ratio of the positive electrode active material particles to the binder and the conductive agent is (90 to 100):(0 to 5):(0 to 5), and optionally (95 to 98.5):(0.5 to 2):(0.5 to 2).

5. The positive electrode sheet according to any one of claims 2 to 4, wherein the thickness of the positive electrode active material layer is 30 μm to 60 μm, and optionally 30 μm to 50 μm.

6. The positive electrode sheet according to any one of claims 2 to 5, wherein the thickness of the polymer layer is 0.01 μm to 2 μm, and optionally 0.01 μm to 1 μm.

7. The mass ratio of the polymer to the organic solvent is (0.1 to 99): (1 to 99.9), optionally (0.1 to 15): (85 to 99.9). The positive electrode sheet according to any one of claims 2 to 6.

8. The positive electrode sheet according to any one of claims 2 to 7, wherein the polymer layer further contains an electrolyte salt.

9. The concentration of the electrolyte salt relative to the total amount of the organic solvent and the electrolyte salt is 0.1 mol / L to 10 mol / L, optionally 0.5 mol / L to 5 mol / L. The positive electrode sheet according to any one of claims 2 to 8.

10. The positive electrode sheet according to any one of claims 2 to 9, wherein the polymer layer further comprises at least one of a film-forming additive and an adsorption additive.

11. The electrochemical oxidation potential window of the film-forming additive is 4 V or less; and / or The positive electrode sheet according to claim 10, wherein the electrochemical oxidation reaction potential window of the adsorption additive is higher than 4V.

12. The mass ratio of the polymer to the film-forming additive and the adsorption additive is (10 to 100): (0 to 90): (0 to 90), optionally (30 to 80): (20 to 70): (20 to 70). The positive electrode sheet according to claim 10 or 11.

13. The positive electrode sheet according to any one of claims 1 to 12, wherein the positive electrode sheet includes a positive electrode active material layer and a protective layer, the positive electrode active material layer being provided on at least one side of the positive electrode current collector, the protective layer being provided on at least one side of the positive electrode active material layer, and the protective layer containing the polymer and the organic solvent.

14. The positive electrode sheet according to claim 13, wherein the thickness of the protective layer is 0.1 μm to 40 μm, optionally 1 μm to 20 μm, and further optionally 1 μm to 10 μm.

15. 15. The positive electrode sheet according to claim 13 or 14, wherein the mass ratio of the polymer to the organic solvent in the protective layer is (0.1 to 99): (1 to 99.9), and optionally (0.1 to 15): (85 to 99.9).

16. The positive electrode sheet according to any one of claims 13 to 15, wherein the protective layer further contains an electrolyte salt.

17. The concentration of the electrolyte salt relative to the total amount of the organic solvent and the electrolyte salt is 0.1 mol / L to 10 mol / L, optionally 0.5 mol / L to 5 mol / L. The positive electrode sheet according to any one of claims 13 to 16.

18. The positive electrode sheet according to any one of claims 13 to 17, wherein the protective layer further comprises at least one of a film-forming additive and an adsorption additive.

19. The electrochemical oxidation potential window of the film-forming additive is 4 V or less; and / or The positive electrode sheet according to claim 18, wherein the electrochemical oxidation reaction potential window of the adsorption additive is higher than 4V.

20. The mass ratio of the polymer to the film-forming additive and the adsorption additive is (10 to 100): (0 to 90): (0 to 90), optionally (30 to 80): (20 to 70): (20 to 70). The positive electrode sheet according to claim 18 or 19.

21. The organic solvent may be a carbonate ester, a carboxylic acid ester, or a C ５ -C １６ the compound includes at least one of an alkane, an aromatic hydrocarbon having an electron-withdrawing group and / or an alkyl group, a nitrile, and a ketone, wherein the electron-withdrawing group is a halogen, —NO ２ , —C≡N, —C≡C, —C≡C and —OCH ３ The positive electrode sheet according to any one of claims 1 to 20, comprising at least one of:

22. The positive electrode sheet according to any one of claims 10 to 21, wherein the film-forming additive comprises at least one of bis(oxalato)borate, difluoro(oxalato)borate, difluorophosphate, methyl 2,2,2-trifluoroethyl carbonate, tris(pentafluorophenyl)borane, fluoroethylene carbonate, fluoroethylene carbonate, methyl 2,2,2-trifluoroethyl carbonate, and trifluoropropylene carbonate.

23. The positive electrode sheet according to any one of claims 10 to 22, wherein the adsorption additive comprises at least one of a carbonate ester, a phosphate ester, a nitrile, and an ionic liquid.

24. The positive electrode sheet according to any one of claims 1 to 23, wherein the polymer has an electrochemical oxidation reaction potential window of greater than 4 V.

25. The positive electrode sheet according to any one of claims 1 to 24, wherein the swelling degree of the polymer is 5% to 2000%, optionally 50% to 1500%.

26. The positive electrode sheet according to any one of claims 1 to 25, wherein the crosslinking density of the polymer is 1% to 100%, and optionally 30% to 70%.

27. The positive electrode sheet according to any one of claims 1 to 26, wherein the number average molecular weight of the polymer is 10,000 to 1,000,000, and optionally 50,000 to 600,000.

28. The polymer has a repeating unit 【Chemistry 1】 Including, R １ -R ４ are each independently H, an alkyl group, F, Cl, Br, I, C≡N, a phenyl group, a pyrrolyl group, a pyrrolone group, a sulfonic acid group, a sulfonate group, a benzenesulfonate group, a carboxylic acid group, or a carbonate group. The positive electrode sheet according to any one of claims 1 to 27.

29. The repeating unit has the following structural formula: 【Chemistry 2】 29. The positive electrode sheet according to claim 28, comprising at least one of:

30. 1. A method for manufacturing a positive electrode sheet, comprising forming a positive electrode sheet comprising a polymer and an organic solvent, The polymer and the organic solvent are located on at least one side of the positive electrode sheet away from the positive electrode current collector, the organic solvent is located on the polymer, and an electrochemical oxidation reaction potential window of the organic solvent is higher than 4 V.

31. 31. The manufacturing method according to claim 30, comprising: forming a positive electrode active material layer containing positive electrode active material particles on at least one side of the positive electrode current collector; and forming a polymer layer containing the polymer and the organic solvent on surfaces of the positive electrode active material particles.

32. a positive electrode active material layer is formed on at least one side of the positive electrode current collector; and forming a protective layer containing a polymer and the organic solvent on at least one side of the positive electrode active material layer.

33. A battery comprising the positive electrode sheet according to any one of claims 1 to 29 or the positive electrode sheet obtained by the method according to any one of claims 30 to 32.

34. Contains an electrolyte, 34. The battery of claim 33, wherein the electrolyte solution comprises a primary solvent, the primary solvent being different from the organic solvent in the positive electrode sheet.

35. 35. The battery according to claim 33 or 34, wherein the electrochemical oxidation reaction potential window of the main solvent is 4 V or less.

36. A power consuming device comprising a battery according to any one of claims 33 to 35.

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