Positive pole piece, battery cell, secondary battery and electric device

Abstract

The invention provides a positive pole piece, a battery cell, a secondary battery and a power utilization device, the positive pole piece comprises a positive active material and a lithium supplement additive, the lithium supplement additive satisfies the following relational expression: R < = Cmin / (100 * m * Q), in the formula, m represents the loading capacity on the positive pole piece per unit area, and the loading capacity comprises the total mass of the positive active material and the lithium supplement additive; cmin represents the minimum multiplying power value applied to the positive pole piece in the actual application process; q represents the theoretical gram capacity of the lithium supplement additive; r represents the mass percentage content of the lithium supplement additive in the loading capacity on the positive pole piece per unit area. The positive pole piece provided by the invention can improve the charging capacity of the battery cell and the secondary battery.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a positive electrode sheet, a battery cell, a secondary battery and an electrical device. Background Art

[0002] Secondary batteries represented by lithium-ion batteries have the characteristics of high capacity and long life, so they are widely used in electronic devices such as mobile phones, laptops, battery cars, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes and electric tools, etc. As the application range of batteries becomes wider and wider, the requirements for the performance of secondary batteries are gradually becoming more stringent. In order to improve the performance of secondary batteries, materials such as positive electrode materials in secondary batteries are usually optimized and improved. However, when the improved positive electrode materials are currently applied to secondary batteries, the secondary batteries still have the problem of poor charging capacity during use. Summary of the invention

[0003] The purpose of the present application is to provide a positive electrode plate, a battery cell, a secondary battery and an electrical device, which can improve the charging capacity of the secondary battery.

[0004] In order to achieve the above-mentioned object, the first aspect of the present application provides a positive electrode plate, comprising a positive electrode active material and a lithium supplement additive, wherein the lithium supplement additive satisfies the following relationship: R≤Cmin / (100*m*Q), wherein m represents the load per unit area on the positive electrode plate, and the load includes the total mass of the positive electrode active material and the lithium supplement additive;

[0005] C min Indicates the minimum rate value applied to the positive electrode plate during actual application;

[0006] Q represents the theoretical gram capacity of the lithium supplement additive;

[0007] R represents the mass percentage of the lithium supplement additive in the load per unit area on the positive electrode plate.

[0008] The positive electrode plate provided in the present application includes a lithium supplement additive, which can increase the gram capacity of the positive electrode active material, thereby increasing the charging capacity of the battery cell. At the same time, the mass percentage of the lithium supplement additive in the positive electrode plate satisfies the above relationship. Therefore, by adjusting the C min , m and Q are regulated to control the mass percentage of the lithium supplement additive in the positive electrode. By controlling the mass percentage of the lithium supplement additive, it is helpful for the lithium supplement additive to slowly de-lithiate during the cycle, so that its capacity can be slowly and continuously released, thereby continuously improving the charging capacity of the battery cell and secondary battery.

[0009] In some embodiments of the present application, the positive electrode plate satisfies the following condition: 0.1%≤R≤20%, optionally 1%≤R≤10%.

[0010] By controlling the mass percentage of the lithium replenishing additive within this range and coordinating it with a specific voltage interval during the actual cycle, it is beneficial for the lithium replenishing additive to slowly de-lithium, allowing its capacity to be slowly released, thereby achieving continuous lithium replenishment during the cycle and a continuous improvement in charging capacity.

[0011] In some embodiments of the present application, the positive electrode sheet satisfies at least one of the following conditions:

[0012] (1)0.01C≤C min ≤1C, optional 0.05C≤C min ≤0.95C;

[0013] (2) 0.1g / mm 2 ≤m≤0.5g / mm 2 , optional 0.2g / mm 2 ≤m≤0.4g / mm 2 ;

[0014] (3) 150mAh / g≤Q≤300mAh / g, optionally 190mAh / g≤Q≤280mAh / g.

[0015] The minimum rate value C applied to the positive electrode during actual application min , the loading amount m per unit area of ​​the positive electrode plate, and the theoretical gram capacity Q of the lithium replenishing additive are within the above ranges, which is helpful to achieve the lithium replenishing effect on the positive electrode and fully improve the gram capacity of the positive electrode active material; at the same time, it is helpful to regulate the mass percentage of the lithium replenishing additive and control the added amount within an appropriate range, thereby helping to achieve a slow and continuous lithium replenishing effect and achieve a continuous improvement in the charging capacity of the battery cell and secondary battery.

[0016] In some embodiments of the present application, the lithium supplement additive includes one or more of lithium manganese oxide, nickel-cobalt-manganese ternary material, nickel-cobalt-aluminum ternary material and lithium nickel oxide, and can be a nickel-cobalt-manganese ternary material.

[0017] In some embodiments of the present application, the positive electrode active material includes one or more of lithium iron phosphate, lithium manganese phosphate, lithium cobalt oxide and lithium manganese iron phosphate, and lithium iron phosphate can be selected.

[0018] The above-mentioned types of positive electrode active materials belong to lithium iron phosphate positive electrode materials, and usually their theoretical gram capacity is relatively low. By adding the above-mentioned types of lithium supplement additives with relatively high gram capacity thereto, it is beneficial to increase the gram capacity of the positive electrode active materials, thereby increasing the charging capacity of the battery cells and secondary batteries.

[0019] The second aspect of the present application also provides a battery cell, comprising the positive electrode plate of the first aspect of the present application.

[0020] In some embodiments of the present application, the cycle voltage range of the battery cell is 2.5V to 3.65V.

[0021] In the actual charge and discharge cycle process, within the above-mentioned cycle voltage range, the capacity of the positive electrode active material can be fully released. At the same time, the lithium supplement additive can slowly delithium during multiple cycles, thereby achieving a continuous and slow release of capacity, which is conducive to the continuous improvement of the charging capacity of the battery cell.

[0022] In some embodiments of the present application, the cycle rate range of the battery cell is 0.33C to 2C.

[0023] In the actual charge and discharge cycle process, the above cycle rate range is applicable to the normal cycle of the positive electrode active material, but within this cycle rate range, the lithium supplement additive can be cycled at a high rate. This high rate cycle can easily destroy the crystal structure of the lithium supplement additive, causing the lithium ions that have been released to be unable to be embedded back into the positive electrode body and remain on the negative electrode side, thereby achieving the effect of replenishing lithium to the negative electrode, which is beneficial to improving the cycle life of the battery cell.

[0024] A third aspect of the present application provides a secondary battery, comprising the battery cell of the second aspect of the present application.

[0025] A fourth aspect of the present application provides an electrical device, comprising the secondary battery of the third aspect of the present application.

[0026] The electric device of the present application includes the secondary battery provided by the present application, and thus has at least the same advantages as the secondary battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic diagram of a secondary battery according to one embodiment of the present application.

[0028] Figure 2 yes Figure 1 An exploded view of a secondary battery according to an embodiment of the present application is shown.

[0029] Figure 3 is a schematic diagram of a secondary battery according to another embodiment of the present application.

[0030] Figure 4 is a schematic diagram of a secondary battery according to another embodiment of the present application.

[0031] Figure 5 yes Figure 4 An exploded view of a secondary battery according to an embodiment of the present application is shown.

[0032] Figure 6 FIG. 1 is a schematic diagram of an electric device using a secondary battery according to an embodiment of the present application as a power source.

[0033] Description of reference numerals:

[0034] 1 battery pack; 2 upper box; 3 lower box; 4 battery module; 5 battery cell; 51 shell; 52 electrode assembly; 53 top cover assembly. DETAILED DESCRIPTION

[0035] Below, the embodiments of the positive electrode plate, battery cell, secondary battery and electric device of the present application are specifically disclosed in detail with appropriate reference to the drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following descriptions are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0036] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0037] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0038] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0039] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0040] At present, the positive electrode active materials used in secondary batteries, especially lithium iron phosphate-based positive electrode active materials, have low gram capacity, so when used in secondary batteries, they usually have poor charging capacity. In order to improve the charging capacity, the commonly used method is to supplement lithium in the positive electrode of the secondary battery, that is, mainly by adding lithium-rich compounds to the positive electrode active materials, using them to undergo irreversible decomposition during formation, and the release of lithium ions to participate in the formation of the negative electrode SEI film, which makes up for the active lithium ions lost for the first time during the formation of traditional lithium-ion batteries, thereby improving the charging capacity. However, this method can only achieve lithium supplementation in the formation stage of the battery, and the lithium-rich compounds can only release the capacity once in the formation stage. It is impossible to slowly and gradually release the capacity of the lithium-rich compounds in the subsequent cycle process and continuously supplement lithium, and it is impossible to achieve a continuous increase in capacity.

[0041] Based on this, the present application proposes a positive electrode plate, which adds a lithium supplement additive and controls the content of the lithium supplement additive in the positive electrode plate, while controlling the voltage and rate range of the positive electrode plate (and the battery cell) during actual use, so that the capacity of the lithium supplement additive can be slowly and gradually released during the actual cycle process, thereby achieving a continuous improvement in the charging capacity of the battery cell and the secondary battery.

[0042] Positive electrode

[0043] The first aspect of the present application provides a positive electrode plate, comprising a positive electrode active material and a lithium supplement additive, wherein the lithium supplement additive satisfies the following relationship: R≤C min / (100*m*Q), where m represents the load per unit area on the positive electrode sheet, and the load includes the total mass of the positive electrode active material and the lithium supplement additive; C min It represents the minimum rate value applied to the positive electrode plate during actual application; Q represents the theoretical gram capacity of the lithium supplement additive; and R represents the mass percentage of the lithium supplement additive in the load per unit area on the positive electrode plate.

[0044] It should be noted that the minimum rate value applied to the positive electrode plate during actual application refers to that after the positive electrode plate is assembled into battery cells of different specifications, in the process of actual application, based on the different specifications of the battery cells and actual usage conditions, there will be corresponding different usage rate range reference values ​​(including upper and lower limits), and the lower limit value of each different usage rate range is the minimum rate value applied to the positive electrode plate during actual application.

[0045] It should be noted that the actual application process refers to the actual cycle process of the battery cell after the positive electrode plates are assembled into battery cells of different specifications.

[0046] The positive electrode plate provided in the present application includes a lithium supplement additive, which can increase the gram capacity of the positive electrode active material, thereby increasing the charging capacity of the battery cell. At the same time, the mass percentage of the lithium supplement additive in the positive electrode plate satisfies the above relationship. Therefore, by adjusting the C min , m and Q are regulated to control the mass percentage of the lithium supplement additive in the positive electrode. By controlling the mass percentage of the lithium supplement additive, it is helpful for the lithium supplement additive to slowly de-lithiate during the cycle, so that its capacity can be slowly and continuously released, thereby continuously improving the charging capacity of the battery cell and secondary battery.

[0047] In addition, in the positive electrode sheet, by limiting the mass percentage of the lithium supplement additive within the range satisfied by the above relationship, it is helpful for the lithium supplement additive to circulate at a high rate. Specifically, when the mass percentage of the lithium supplement additive is controlled within the range satisfied by the above relationship, in the actual cycle process, the charge and discharge rate applicable to the positive electrode active material will be a high rate for the lithium supplement additive in the above content range, that is, under the charge and discharge rate of the normal cycle applicable to the positive electrode active material, the lithium supplement additive can be circulated at a high rate. This high-rate cycle can easily destroy the crystal structure of the lithium supplement additive, causing the lithium ions that are released to remain on the negative electrode side because they cannot be re-embedded back into the positive electrode body, thereby achieving the effect of replenishing lithium to the negative electrode, thereby improving the cycle life of the battery cell and the secondary battery. At the same time, by limiting the mass percentage of the lithium supplement additive within the range satisfied by the above relationship, while increasing the gram capacity, it will not affect the cycle stability of the positive electrode active material.

[0048] In the above relationship, the physical phase of the lithium supplement additive added to the electrode can be determined by testing the XRD (X-ray diffraction spectrum) of the positive electrode before the cycle, and the chemical structure can be determined; then, by testing the ICP (inductively coupled plasma mass spectrometry) of the positive electrode, the metal elements other than iron in the electrode can be determined, and the mass percentage of the lithium supplement additive in the positive electrode, i.e., R, can be determined through the test results of XRD and ICP.

[0049] In the above relationship, the addition amounts of positive active material and lithium supplement additive in the positive electrode sheet before the cycle can be determined by XRD and ICP tests, respectively, which are m1 and m2, thereby obtaining the total mass of the positive active material layer loaded on the positive electrode sheet per unit area, that is, m=m1+m2. Then, a button battery is made with the positive electrode sheet to test the capacity value of the button battery. For example, it can be charged at a constant current of 0.5C at room temperature until the voltage is higher than 4.35V, and further charged at a constant voltage of 4.35V until the current is lower than 0.05C, so that it is in a fully charged state of 4.35V, and then the button battery is discharged at a constant current of 1C to a voltage of 3V (cut-off voltage), and the released capacity value is recorded as q, which is the capacity value of the button battery. Based on this, according to the capacity value q, the added amount m1 of the positive electrode active material and its theoretical gram capacity (denoted as q1), and the added amount m2 of the lithium supplement additive, the theoretical gram capacity Q of the added lithium supplement additive can be obtained through the formula q=(m1 / m)*q1+(m2 / m)*Q.

[0050] In some embodiments, 0.01C≤C min ≤1C. For example, C min It can be 0.01C, 0.05C, 0.08C, 0.1C, 0.3C, 0.5C, 0.8C, 1C or any range thereof. Optionally, 0.05C≤C min ≤0.95C.

[0051] The minimum rate value C applied to the positive electrode during actual application min Being within the above range, it is helpful to exert the capacity of the positive electrode active material and regulate the mass percentage of the lithium replenishing additive. At the same time, it can also enable the lithium replenishing additive to circulate at a high rate, thereby replenishing lithium to the negative electrode side, thereby comprehensively improving the capacity and cycle performance of the battery cell and secondary battery.

[0052] In some embodiments, 0.1 g / mm 2 ≤m≤0.5g / mm 2 For example, m can be 0.1 g / mm 2 , 0.2g / mm 2 , 0.3g / mm 2 , 0.4g / mm 2 , 0.5g / mm 2 Or within the range of any of the above values. Optionally, 0.2 g / mm 2 ≤m≤0.4g / mm 2 .

[0053] The loading amount m per unit area of ​​the positive electrode plate, that is, the total mass of the positive electrode active material and the lithium supplement additive loaded on the positive electrode plate per unit area, is within the above range, which helps the lithium supplement additive to fully exert its lithium supplement effect on the positive electrode, and helps to slowly and continuously release the capacity of the lithium supplement additive, thereby continuously improving the charging capacity of the battery cell and the secondary battery.

[0054] In some embodiments, 150 mAh / g≤Q≤300 mAh / g. For example, Q can be 150 mAh / g, 170 mAh / g, 190 mAh / g, 210 mAh / g, 230 mAh / g, 250 mAh / g, 270 mAh / g, 290 mAh / g, 300 mAh / g, or any range thereof. Optionally, 190 mAh / g≤Q≤280 mAh / g.

[0055] The theoretical gram capacity Q of the lithium replenishing additive is within the above range, which helps to achieve the lithium replenishing effect on the positive electrode and fully improve the gram capacity of the positive electrode active material; at the same time, it helps to regulate the mass percentage of the lithium replenishing additive and control the added amount within an appropriate range, thereby helping to achieve a slow and continuous lithium replenishing effect and achieve a continuous improvement in the charging capacity of the battery cell and secondary battery.

[0056] In some embodiments, 0.01%≤R≤20%. For example, R can be 0.01%, 0.05%, 0.08%, 0.1%, 0.5%, 0.8%, 1%, 3%, 5%, 8%, 10%, 13%, 15%, 18%, 20%, or any range thereof. Optionally, 1%≤R≤10%.

[0057] In the above relationship, by controlling the value range of each parameter, it is helpful to regulate the mass percentage of the lithium supplement additive and control it within the above range. By controlling the mass percentage of the lithium supplement additive within this range and coordinating it with a specific voltage interval during the actual cycle, it is beneficial for the lithium supplement additive to slowly de-lithium, so that its capacity can be slowly released, and continuous lithium supplementation can be achieved during the cycle, achieving a continuous improvement in charging capacity. At the same time, it also helps the lithium supplement additive to circulate at a high rate to achieve the effect of replenishing lithium to the negative electrode, thereby improving the cycle life of the battery cell and secondary battery.

[0058] As a non-limiting example, the positive electrode contains 1g of lithium iron phosphate, whose capacity is 160mAh; if 0.1g of a lithium supplement additive with a theoretical gram capacity of 180mAh / g is added, in the actual cycle process, by coordinating with the specific cycle voltage range of the battery cell, the lithium supplement additive can achieve slow lithium delithiation, thereby slowly and continuously increasing the capacity of the battery cell, and the capacity can be increased to: 160*(1 / 1.1)+180*(0.1 / 1.1)=162mAh.

[0059] In some embodiments, the lithium supplement additive includes but is not limited to one or more of lithium manganese oxide, nickel-cobalt-manganese ternary material, nickel-cobalt-aluminum ternary material and lithium nickel oxide, and may be a nickel-cobalt-manganese ternary material.

[0060] In some embodiments, the positive electrode active material includes, but is not limited to, one or more of lithium iron phosphate, lithium manganese phosphate, lithium cobalt oxide, and lithium manganese iron phosphate, and lithium iron phosphate may be selected.

[0061] The above-mentioned types of positive electrode active materials belong to lithium iron phosphate positive electrode materials, and usually their theoretical gram capacity is relatively low. By adding the above-mentioned types of lithium supplement additives with relatively high gram capacity thereto, it is beneficial to increase the gram capacity of the positive electrode active materials, thereby increasing the charging capacity of the battery cells and secondary batteries.

[0062] The positive electrode sheet includes a positive electrode active material layer and a positive electrode current collector, wherein the positive electrode active material layer is disposed on at least one surface of the positive electrode current collector.

[0063] It can be understood that the positive electrode active material layer includes the positive electrode active material and lithium supplement additive mentioned above in this application, that is, the positive electrode active material and lithium supplement additive included in the positive electrode plate are arranged in the positive electrode plate of this application in the form of a positive electrode active material layer.

[0064] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material layer is disposed on any one or both of the two facing surfaces of the positive electrode current collector.

[0065] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0066] In some embodiments, the positive electrode active material may also include other positive electrode active materials for batteries that are well known in the art. As an example, other positive electrode active materials may include at least one of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. One or more of these positive electrode active materials may be used in combination with one or more of the positive electrode active materials described above in this application. Among them, examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3Mn 1 / 3 O2 (also referred to as NCM 333 )、LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 )、LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 )、LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 )、LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and its modified compounds, etc. Examples of lithium-containing phosphates with an olivine structure may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[0067] It should be noted that the battery will be accompanied by Li deintercalation and consumption during the charge and discharge process, and the molar content of Li is different when the battery is discharged to different states. In the list of positive electrode active materials in this application, the molar content of Li is the initial state of the material, that is, the state before feeding. The positive electrode active material is used in the battery system, and the molar content of Li will change after charge and discharge cycles.

[0068] In the enumeration of positive electrode active materials in the present application, the molar content of O is only a theoretical value. O release from the lattice will cause the molar content of O to change, and the actual molar content of O will fluctuate.

[0069] In some embodiments, the positive electrode active material may also include at least one of the following materials: sodium transition metal oxide, polyanionic compound and Prussian blue compound. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries can also be used. One or more of these positive electrode active materials can be used in combination with one or more of the positive electrode active materials described above in the present application.

[0070] As an optional technical solution of the present application, in the sodium transition metal oxide, the transition metal includes at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce. The sodium transition metal oxide is, for example, Na x MO2, wherein M includes one or more of Ti, V, Mn, Co, Ni, Fe, Cr and Cu, and 0<x≤1.

[0071] As an optional technical solution of the present application, the polyanionic compound can be a compound having sodium ions, transition metal ions and tetrahedral (YO4) n- A class of compounds with anionic units. Transition metals include at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce; Y includes at least one of P, S and Si; n represents (YO4) n- valence state.

[0072] Polyanionic compounds can also be those with sodium ions, transition metal ions, tetrahedral (YO4) n- A class of compounds containing anion units and halogen anions. The transition metal includes at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce; Y includes at least one of P, S and Si, and n represents (YO4) n- valence state; the halogen includes at least one of F, Cl and Br.

[0073] Polyanionic compounds can also be sodium ions, tetrahedral (YO4) n- Anion unit, polyhedral unit (ZO y ) m+ and an optional halogen anion. Y includes at least one of P, S and Si, and n represents (YO4) n- valence state; Z represents a transition metal, including at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce, and m represents (ZO y )m+ valence state; the halogen includes at least one of F, Cl and Br.

[0074] Polyanionic compounds include NaFePO4, Na3V2(PO4)3 (sodium vanadium phosphate, abbreviated as NVP), Na4Fe3(PO4)2 (P2O7), NaM'PO4F (M' includes one or more of V, Fe, Mn and Ni) and Na3(VO y )2(PO4)2F 3-2y At least one of (0≤y≤1).

[0075] Prussian blue compounds can be compounds containing sodium ions, transition metal ions and cyanide ions (CN-). Transition metals include at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce. Prussian blue compounds are, for example, Na a Me b Me' c (CN)6, wherein Me and Me' each independently include at least one of Ni, Cu, Fe, Mn, Co and Zn, 0<a≤2, 0<b<1, 0<c<1.

[0076] In some embodiments, the positive electrode active material layer may further optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0077] In some embodiments, the positive electrode active material layer may further include a conductive agent, which may include, for example, at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0078] In some embodiments, the positive electrode sheet can be prepared in the following manner: the components for preparing the positive electrode sheet, such as the positive electrode active material, the lithium supplement additive, the conductive agent, the binder and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0079] In some embodiments, the mass proportion of the lithium supplement additive in the positive electrode slurry is 0.1% to 20%. For example, the mass proportion of the lithium supplement additive in the positive electrode slurry can be 0.1%, 0.5%, 0.8%, 1%, 3%, 5%, 8%, 10%, 13%, 15%, 18%, 20% or within the range of any of the above values.

[0080] In some embodiments, the mass proportion of the positive electrode active material in the positive electrode slurry is 90% to 99%. For example, the mass proportion of the positive electrode active material in the positive electrode slurry can be 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or within the range of any of the above values.

[0081] The positive electrode sheet of the present application does not exclude other additional functional layers in addition to the positive electrode active material layer. For example, in some embodiments, the positive electrode sheet of the present application also includes a conductive primer layer (for example, composed of a conductive agent and a binder) sandwiched between the positive electrode collector and the positive electrode active material layer and disposed on the surface of the positive electrode collector. In some other embodiments, the positive electrode sheet of the present application also includes a protective layer covering the surface of the positive electrode active material layer.

[0082] Negative electrode

[0083] The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode active material layer includes a negative electrode active material.

[0084] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material layer is disposed on any one or both of the two facing surfaces of the negative electrode current collector.

[0085] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, copper foil may be used. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0086] In some embodiments, the negative electrode active material may adopt the negative electrode active material for the battery known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0087] In some embodiments, the negative electrode active material layer may further include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).

[0088] In some embodiments, the negative electrode active material layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0089] In some embodiments, the negative electrode active material layer may further optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0090] In some embodiments, the negative electrode sheet can be prepared in the following manner: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0091] The negative electrode sheet of the present application does not exclude other additional functional layers in addition to the negative electrode active material layer. For example, in some embodiments, the negative electrode sheet of the present application also includes a conductive primer layer (for example, composed of a conductive agent and a binder) sandwiched between the negative electrode current collector and the negative electrode active material layer and disposed on the surface of the negative electrode current collector. In some other embodiments, the negative electrode sheet of the present application also includes a protective layer covering the surface of the negative electrode active material layer.

[0092] Electrolytes

[0093] The electrolyte plays the role of conducting ions between the positive electrode and the negative electrode. The present application has no specific restrictions on the type of electrolyte, which can be selected according to needs. For example, the electrolyte can be liquid, gel or all-solid.

[0094] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.

[0095] In some embodiments, the electrolyte salt may be a lithium salt. As an example, the lithium salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorobis(oxalatophosphate), and lithium tetrafluorooxalatophosphate.

[0096] In some embodiments, the electrolyte salt may also be a sodium salt. As an example, the sodium salt includes but is not limited to at least one of NaPF6, NaClO4, NaBCl4, NaSO3CF3 and Na(CH3)C6H4SO3. The above sodium salts may be used alone or in combination of two or more.

[0097] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0098] In some embodiments, the electrolyte may further include additives, such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.

[0099] Isolation film

[0100] In some embodiments, the secondary battery further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical stability and mechanical stability can be selected.

[0101] In some embodiments, the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The isolation membrane can be a single-layer film or a multi-layer composite film, without particular limitation. When the isolation membrane is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0102] The second aspect of the present application provides a battery cell, comprising the positive electrode sheet of the first aspect of the present application.

[0103] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly by a winding process or a lamination process.

[0104] In some embodiments, the battery cell includes an electrode assembly and a casing, wherein the casing can be used to encapsulate the electrode assembly and the electrolyte.

[0105] In some embodiments, the shell may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.; or a soft package, such as a bag-type soft package. The material of the soft package may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0106] In some embodiments, during the actual charge and discharge cycle, the cycle voltage interval of the battery cell is 2.5 V to 3.65 V. For example, the cycle voltage of the battery cell may be 2.5 V, 2.65 V, 2.8 V, 2.95 V, 3.1 V, 3.25 V, 3.4 V, 3.65 V or any range thereof.

[0107] In the actual charge and discharge cycle process, within the above-mentioned cycle voltage range, the capacity of the positive electrode active material can be fully released. At the same time, since the voltage range of the lithium supplement additive itself is higher than the cycle voltage range, when cycling within this voltage range, combined with the specific addition amount of the aforementioned lithium supplement additive in the positive electrode plate (that is, the mass percentage of the lithium supplement additive in the positive electrode plate must satisfy the aforementioned relationship), the lithium supplement additive can achieve slow lithium delithiation during multiple cycles, thereby achieving continuous and slow release of capacity, which is beneficial to achieving a continuous improvement in the charging capacity of the battery cell.

[0108] In some embodiments, during the actual charge and discharge cycle, the cycle rate of the battery cell is in the range of 0.33C to 1C. For example, the cycle rate of the battery cell may be 0.33C, 0.5C, 1C or any range thereof.

[0109] In the actual charge and discharge cycle process, the above cycle rate range is applicable to the normal cycle of the positive electrode active material, but under this cycle rate range, combined with the specific addition amount of the aforementioned lithium supplement additive in the positive electrode plate (that is, the mass percentage of the lithium supplement additive in the positive electrode plate must satisfy the aforementioned relationship), the lithium supplement additive can be cycled at a high rate. This high-rate cycle can easily destroy the crystal structure of the lithium supplement additive, resulting in the inability of the lithium ions released from it to be embedded back into the positive electrode body and remain on the negative electrode side, thereby achieving the effect of replenishing lithium to the negative electrode, which is beneficial to improving the cycle life of the battery cell.

[0110] As a non-limiting example, the positive electrode contains 0.9g of lithium iron phosphate and 0.1g of a lithium supplement additive with a theoretical gram capacity of 180mAh / g, and its capacity is 162mAh. If the minimum rate of the battery cell during actual charging and discharging is 0.3C, the rate actually applied to the particle level of the lithium supplement additive is: 0.3*162 / (180*0.1)=2.7C, and the lithium supplement additive is very prone to material damage when circulating at this high rate, resulting in the destruction of the crystal structure, so that the lithium ions cannot be embedded back and remain on the negative electrode side, thereby replenishing the negative electrode with lithium.

[0111] The third aspect of the present application provides a secondary battery, which may include the battery cell of the second aspect of the present application, or the secondary battery may also be directly assembled from components such as an electrode assembly and an outer packaging.

[0112] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly by a winding process or a lamination process.

[0113] In some embodiments, an outer package may be used to package the electrode assembly and the electrolyte.

[0114] In some embodiments, the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the secondary battery may also be a soft package, such as a bag-type soft package. The material of the soft package may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0115] The present application has no particular limitation on the shape of the secondary battery, which may be cylindrical, square or any other shape. Figure 1 The battery cell 5 is a square structure as an example.

[0116] In some embodiments, reference Figure 2 , the outer packaging may include a shell 51 and a cover plate 53. Among them, the shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can form an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the battery cell 5 can be one or more, and those skilled in the art can select according to specific actual needs.

[0117] In some embodiments, the secondary battery may also be a battery module composed of a plurality of battery cells. The battery module may contain a plurality of battery cells, and the specific number may be adjusted by those skilled in the art according to the application and capacity of the battery module.

[0118] Figure 3 4 is an example of a battery module. Figure 3 In the battery module 4, the plurality of battery cells 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they may also be arranged in any other manner. Further, the plurality of battery cells 5 may be fixed by fasteners.

[0119] Optionally, the battery module 4 may further include a housing having a receiving space, and the plurality of battery cells 5 are received in the receiving space.

[0120] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery pack.

[0121] In some embodiments, the battery cells mentioned above may also be directly assembled into a battery pack, and the number of battery cells contained in the battery pack may be adjusted according to the application and capacity of the battery pack.

[0122] Figure 4 and Figure 5 1 is a battery pack 1 as an example. Figure 4 and Figure 5 The battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can cover the lower box body 3 and form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0123] In addition, the present application also provides an electric device, which includes a secondary battery provided in the present application. The secondary battery can be used as a power source for the electric device, or as an energy storage unit for the electric device. The electric device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto.

[0124] As the electrical device, a secondary battery can be selected according to its usage requirements.

[0125] Figure 6 The power consumption device is taken as an example. The power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. In order to meet the high power and high energy density requirements of the power consumption device for the secondary battery, a battery pack or a battery module can be used.

[0126] Another example of a device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is usually required to be thin and light, and a secondary battery may be used as a power source.

[0127] Example

[0128] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0129] Example 1

[0130] Preparation of positive electrode

[0131] The positive electrode active material is lithium iron phosphate (LiFePO4), NCM (LiNi 0.7 Co 0.15 Mn 0.15 O2) material, conductive agent Super-P, and adhesive polyvinylidene fluoride (PVDF) are dissolved in solvent N-methylpyrrolidone in a mass ratio of 94:2:2:2 and mixed evenly to form a positive electrode slurry. The positive electrode slurry is then evenly coated on the front and back sides of the current collector aluminum foil, and then dried at 85°C. After cold pressing and cutting, the positive electrode sheet is obtained.

[0132] Preparation of negative electrode

[0133] The negative electrode active material graphite, the conductive agent acetylene black, the thickener sodium carboxymethyl cellulose (CMC), and the binder (SBR) are dissolved in the solvent deionized water in a weight ratio of 95:1:2:1, and then evenly mixed with the deionized water to prepare a negative electrode slurry; then the negative electrode slurry is coated on the front and back sides of the collector copper foil, dried, and then cold pressed and cut to obtain the negative electrode sheet.

[0134] Preparation of electrolyte

[0135] In an argon atmosphere glove box with a water content of <10ppm, EC, PC, and DMC are mixed in a weight ratio of EC:PC:DMC=3:3:3 to obtain a mixed organic solvent, and then the fully dried lithium salt LiPF6 is dissolved in the above mixed organic solvent. After stirring evenly, an electrolyte is obtained, in which the concentration of LiPF6 is 1 mol / L.

[0136] Preparation of isolation membrane

[0137] PE porous film is used as the isolation membrane.

[0138] Preparation of lithium-ion batteries

[0139] The positive electrode sheet, the separator and the negative electrode sheet are made into a soft-pack battery cell through a winding process, and then the battery cell is filled with liquid, left to stand at high temperature, and tested for capacity after formation to obtain a lithium-ion battery.

[0140] Embodiments 2 to 18

[0141] The preparation method of the positive electrode sheet and the lithium-ion battery is similar to that of Example 1, except that the positive electrode sheet and the related parameters in the preparation process are adjusted, and the specific parameters are shown in Table 1 below. Wherein, " / " indicates that the corresponding parameter does not exist.

[0142] Comparative Example 1

[0143] The preparation method of the positive electrode plate and the lithium-ion battery is similar to that of Example 1, except that no lithium supplement additive is added to the positive electrode plate.

[0144] Comparative Example 2

[0145] The preparation method of the positive electrode sheet and the lithium ion battery is similar to that of Example 1, except that: the positive electrode sheet does not satisfy the relationship R≤C min / (100*m*Q).

[0146] Table 1

[0147]

[0148]

[0149] In addition, the positive electrode sheets and lithium-ion batteries obtained in the above-mentioned Examples 1 to 18 and Comparative Examples 1 to 2 were subjected to relevant performance tests, and the test results are shown in Table 2 below.

[0150] Test Section

[0151] (1) Charging capacity test

[0152] Under the condition of ambient temperature of 25℃, ① use a constant current charge rate of 0.33C to charge the battery cell to 3.65V, and then charge it to 0.05C at a constant voltage. The capacity measured in this step is the charging capacity value. ② Let it stand for 30 minutes. ③ Use a constant current discharge rate of 0.33C to discharge the battery cell to 2.5V.

[0153] Charging capacity per unit area = charging capacity / positive electrode area.

[0154] (2) Cycle life test

[0155] ① When the ambient temperature reaches the required temperature for the cycle, start the cycle test process, ② Charge the battery cell to 3.65V at a rate of 1C, and then charge it to 0.05C, ③ Let it stand for 5 minutes, ④ Discharge the battery cell to 2.5V at a rate of 1C, ⑤ Let it stand for 5 minutes, ⑥ Repeat steps ②-⑤ to test the cycle performance of the battery cell.

[0156] Capacity retention rate = (charge capacity after 400 / 800 cycles) / first cycle charge capacity

[0157] Capacity retention rate decrease = (capacity retention rate after 400 cycles - capacity retention rate after 800 cycles) / capacity retention rate after 400 cycles

[0158] Table 2

[0159]

[0160]

[0161] In the above Table 2, by comparing the embodiment with the comparative example 1, it can be seen that the capacity retention rate of the embodiment after 400 cycles and the capacity retention rate after 800 cycles are both higher than those of the comparative example 1, indicating that compared with not adding the lithium replenishing additive, the present application can improve the charging capacity of the battery after adding the lithium replenishing additive to the positive electrode plate.

[0162] Comparing the embodiment with the comparative example 2, it can be seen that the capacity retention rate of the embodiment after 400 cycles and the capacity retention rate after 800 cycles are higher than those of the comparative example 2, and the decrease in the capacity retention rate is also higher than that of the comparative example 2, indicating that when the positive electrode sheet does not satisfy the relationship R≤C min / (10*m*Q), the lithium supplement additive has little effect on improving the battery charging capacity, and it is difficult to achieve a slow increase in capacity.

[0163] Comparing Example 1 with Examples 16 to 18, it can be seen that the decrease in capacity retention rate of Examples 16 to 18 is significantly lower than that of Example 1, indicating that when the cycle voltage range or the cycle rate range is not within the scope of the present application, it will have a certain impact on the slow release of the capacity of the lithium supplement additive.

[0164] It should also be noted that in Examples 6 to 7, Examples 10 to 13 and Example 15, since the load m per unit area on the positive electrode sheet is lower than that in other examples, the charging capacity per unit area is correspondingly lower than that in other examples.

[0165] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and the same effect as the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A positive electrode sheet, characterized in that: The invention comprises a positive electrode active material and a lithium supplement additive, wherein the lithium supplement additive satisfies the following relationship: R≤C min / (100*m*Q), In the formula, m represents the loading amount per unit area on the positive electrode sheet, and the loading amount includes the total mass of the positive electrode active material and the lithium supplement additive; C min Indicates the minimum rate value applied to the positive electrode plate during actual application; Q represents the theoretical gram capacity of the lithium supplement additive; R represents the mass percentage of the lithium supplement additive in the load per unit area on the positive electrode plate.

2. The positive electrode sheet according to claim 1, characterized in that: The following conditions are met: 0.1%≤R≤20%, optionally 1%≤R≤10%.

3. The positive electrode sheet according to claim 1 or 2, characterized in that: Satisfy at least one of the following conditions: (1)0.01C≤C min ≤1C, optional 0.05C≤C min ≤0.95C; (2) 0.1g / mm 2 ≤m≤0.5g / mm 2 , optional 0.2g / mm 2 ≤m≤0.4g / mm 2 ; (3) 150mAh / g≤Q≤300mAh / g, optionally 190mAh / g≤Q≤280mAh / g.

4. The positive electrode sheet according to claim 1 or 2, characterized in that: The lithium supplement additive includes one or more of lithium manganese oxide, nickel-cobalt-manganese ternary material, nickel-cobalt-aluminum ternary material, lithium cobalt oxide and lithium nickel oxide, and can be a nickel-cobalt-manganese ternary material.

5. The positive electrode sheet according to claim 1 or 2, characterized in that: The positive electrode active material includes one or more of lithium iron phosphate, lithium manganese phosphate and lithium manganese iron phosphate, and lithium iron phosphate can be selected.

6. A battery cell, characterized in that: The invention comprises the positive electrode sheet as described in any one of claims 1 to 5.

7. The battery cell according to claim 6, characterized in that: The cycle voltage range of the battery cell is 2.5V to 3.65V.

8. The battery cell according to claim 6 or 7, characterized in that: The cycle rate range of the battery cell is 0.33C to 2C.

9. A secondary battery, characterized in that: A battery cell comprising the battery cell described in any one of claims 6 to 8.

10. An electrical device, characterized in that: A secondary battery comprising the secondary battery according to claim 9.

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