Negative electrode plate, secondary battery and power consumption device

Abstract

The present application provides a negative electrode plate, a secondary battery, and a power consumption device, the negative electrode plate including a negative electrode current collector, and a first active layer and a second active layer located on at least one surface of the negative electrode current collector, the first active layer being located between the negative electrode current collector and the second active layer, the first active layer including a first silicon-based material, and the second active layer including a second silicon-based material, the sphericity of the first silicon-based material being greater than the sphericity of the second silicon-based material, the sphericity of the first silicon-based material being 0.6 or greater.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority from a Chinese patent application filed on July 11, 2023, bearing application number 2023108473017, entitled "Negative electrode plate, secondary battery and power consumption device," the entire contents of which are incorporated herein by reference.

[0002] The present application relates to the field of secondary battery technology, and in particular to negative electrode plates, secondary batteries and power consuming devices. [Background technology]

[0003] The statements herein merely provide background information related to the present application and may not necessarily constitute prior art.

[0004] The use of silicon-based materials in secondary batteries can effectively improve the energy density of the battery, but the structural stability of electrodes containing silicon-based materials is relatively poor after charging the battery, which may reduce the cycle performance of the battery. Summary of the Invention

[0005] The present application provides a negative electrode plate, comprising: a negative electrode current collector; and a first active layer and a second active layer located on at least one surface of the negative electrode current collector, the first active layer being located between the negative electrode current collector and the second active layer, the first active layer comprising a first silicon-based material, and the second active layer comprising a second silicon-based material, wherein the sphericity of the first silicon-based material is greater than the sphericity of the second silicon-based material, and the sphericity of the first silicon-based material is 0.6 or greater.

[0006] In the above-mentioned negative electrode plate, the compatibility of the first silicon-based material with appropriate sphericity with the second silicon-based material can improve the stability of the negative electrode plate structure and further improve the cycle performance of the battery.

[0007] In some embodiments, the sphericity of the first silicon-based material is 0.6 to 1.

[0008] In some embodiments, the sphericity of the second silicon-based material is 0.3 to 0.8.

[0009] In some embodiments, the weight percentage of the active material in the first active layer that is the first silicon-based material is ≦ the weight percentage of the active material in the second active layer that is the second silicon-based material.

[0010] In some embodiments, the weight percentage of the active material in the first active layer that is the first silicon-based material is ≦15%.

[0011] In some embodiments, the mass percentage of the second silicon-based material in the active material in the second active layer is 5% to 40%.

[0012] In some embodiments, the Dv50 of the first silicon-based material is less than or equal to the Dv50 of the second silicon-based material.

[0013] In some embodiments, the first silicon-based material has a Dv50 of 4 μm to 8 μm.

[0014] In some embodiments, the second silicon-based material has a Dv50 of 6 μm to 10 μm.

[0015] In some embodiments, the specific surface area of ​​the first silicon based material is ≦ the specific surface area of ​​the second silicon based material.

[0016] In some embodiments, the specific surface area of ​​the first silicon-based material is 0.5 m 2 / g~2.5m 2 / g.

[0017] In some embodiments, the specific surface area of ​​the second silicon-based material is greater than 1 m 2 / g~4m2 / g.

[0018] In some embodiments, the thickness of the first active layer is greater than or equal to the thickness of the second active layer.

[0019] In some embodiments, the first active layer has a thickness of 20 μm to 40 μm.

[0020] In some embodiments, the second active layer has a thickness of 20 μm to 40 μm.

[0021] In some embodiments, the first silicon-based material comprises elemental oxygen.

[0022] In some embodiments, the mass percentage of oxygen elements in the first silicon-based material is 40% to 60%.

[0023] In some embodiments, the second silicon-based material comprises elemental oxygen.

[0024] In some embodiments, the mass percentage of oxygen elements in the second silicon-based material is ≦10%.

[0025] In some embodiments, the first silicon-based material comprises elemental carbon.

[0026] In some embodiments, the mass percentage of carbon element in the first silicon-based material is ≦8%.

[0027] In some embodiments, the second silicon-based material comprises elemental carbon.

[0028] In some embodiments, the mass percentage of carbon elements in the second silicon-based material is 40% to 60%.

[0029] In some embodiments, the first silicon-based material comprises a doping metal element, and the doping metal element comprises at least one of an alkali metal element and an alkaline earth metal element.

[0030] In some embodiments, the mass percentage of the doping metal element in the first silicon-based material is ≦10%.

[0031] In some embodiments, a carbon coating layer is coated on the surface of the first silicon-based material and / or the surface of the second silicon-based material.

[0032] In some embodiments, the carbon coating layer has a thickness of 10 nm to 300 nm.

[0033] In some embodiments, the first active layer further comprises a first graphite.

[0034] In some embodiments, the mass percentage of the active material in the first active layer that is the first graphite is ≧85%.

[0035] In some embodiments, the second active layer further comprises a second graphite.

[0036] In some embodiments, the mass percentage of the second graphite in the active material in the second active layer is 60% to 95%.

[0037] The present application further provides a secondary battery including the negative electrode plate.

[0038] The present application further provides a power consuming device including at least one of the negative electrode plate and the secondary battery.

[0039] In order to more clearly explain the technical solution of the present application, the following briefly introduces the drawings used in the present application. It is obvious that the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on the drawings without any creative efforts. [Brief explanation of the drawings]

[0040] [Figure 1] 1 is a schematic diagram of a secondary battery according to an embodiment of the present application; [Figure 2] FIG. 2 is an exploded view of the secondary battery shown in FIG. 1 according to the embodiment of the present application. [Figure 3] 1 is a schematic diagram of a power consumption device powered by a secondary battery according to an embodiment of the present application; DETAILED DESCRIPTION OF THE INVENTION

[0041] To better describe and explain the embodiments and / or examples of those inventions disclosed herein, reference may be made to one or more drawings, in which additional details or examples for describing the drawings should not be considered as limiting the scope of any of the disclosed inventions, the presently described embodiments and / or examples, and the best modes of those inventions as currently understood.

[0042] To facilitate understanding of the present application, the following more fully describes the present application with reference to the associated drawings. The drawings illustrate preferred embodiments of the present application. However, the present application may be embodied in many different forms and is not limited to the embodiments set forth herein. Rather, the purpose of providing these embodiments is to provide a more thorough and complete understanding of the disclosure of the present application.

[0043] 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 pertains. The terms used herein are for the purpose of describing specific examples only and are not intended to be limiting of the present application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0044] The "ranges" disclosed herein may be defined in the form of lower and upper limits. A given range is defined by selecting one lower limit and one upper limit, and the selected lower and upper limits define the boundaries of the particular range. Such defined ranges may be inclusive or exclusive of the endpoints, and any endpoint may be independently inclusive or exclusive, and any combination is possible; i.e., any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if 1 and 2 are listed as minimum range values ​​and 3, 4, and 5 are further listed as maximum range values, the ranges 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5 are all contemplated. In this application, unless otherwise specified, a numerical range of "a to b" represents a shorthand representation of any combination of real numbers a to b, where a and b are both real numbers. For example, a numerical range of "0 to 5" represents a list of all real numbers between "0 and 5" already listed in this specification, and "0 to 5" is merely a shorthand representation of a combination of these numbers. Furthermore, expressing a parameter as an integer ≧2 is equivalent to listing the parameter as, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For example, expressing a parameter as an integer selected from "2 to 10" is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0045] As used herein, unless otherwise limited, the terms "plurality," "plurality," and the like refer to a number greater than or equal to 2. For example, "one or more" refers to one or more than two.

[0046] Unless otherwise stated, all embodiments and optional embodiments in the present application can be combined with each other to form a new technical solution.

[0047] An "embodiment" referred to in this specification means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment or embodiment of the present application. The appearances of this phrase in various locations in the specification do not necessarily all refer to the same embodiment, nor are they mutually exclusive independent or alternative embodiments of other embodiments. Those skilled in the art can explicitly and implicitly understand that the embodiments described in this specification can be combined with other embodiments. The term "embodiment" referred to in this specification has a similar meaning.

[0048] As will be understood by those skilled in the art, in the methods of the embodiments or examples, the order of steps described does not imply a strict execution order or constitute any limitation on the implementation process. The detailed execution order of steps should be determined by their functions and possible underlying logic. Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, when a method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. For example, when a method described above may further include step (c), it 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.

[0049] In this application, open technical features or technical solutions described with words such as "comprise," "include," or "comprise" do not exclude additional members other than the enumerated members, unless otherwise specified, and can be considered to provide not only a closed feature or solution consisting of the enumerated members, but also an open feature or solution including additional members in addition to the enumerated members. For example, when A includes a1, a2, and a3, unless otherwise specified, it may further include other members or may not include additional members, and can be considered to provide not only a feature or solution in which "A is composed of a1, a2, and a3," but also a feature or solution in which "A not only includes a1, a2, and a3, but also includes other members."

[0050] In this application, unless otherwise specified, it can be understood that A (for example, B) means that B represents one non-limiting example of A, and that A is not limited to B.

[0051] In this application, "optionally", "optional" and "optionally" refer to the possibility of being present or absent, that is, to selecting one of the two parallel solutions of "present" or "absent". When "optionally" appears in multiple places in a technical solution, unless otherwise specified and unless there is a contradictory or mutually restrictive relationship, the "option" in each clause is independent.

[0052] One embodiment of the present application provides a negative electrode plate, the negative electrode plate including a negative electrode current collector and a first active layer and a second active layer located on at least one surface of the negative electrode current collector, the first active layer being located between the negative electrode current collector and the second active layer, the first active layer including a first silicon-based material, and the second active layer including a second silicon-based material, the sphericity of the first silicon-based material being greater than the sphericity of the second silicon-based material, the sphericity of the first silicon-based material being 0.6 or greater.

[0053] In the negative electrode plate of this embodiment, the compatibility of the first silicon-based material and the second silicon-based material with appropriate sphericity can improve the stability of the negative electrode plate structure and further improve the cycle performance of the battery.

[0054] As can be understood, in this application, sphericity refers to the ratio of the shortest diameter to the longest diameter of a material, which can be tested by the following method: using a Malvern automatic image particle size analyzer to capture and process images of a certain number (≧20) of dispersed particles, and then using image-guided Raman spectroscopy (MDRS) to accurately analyze the microstructure and morphology of the particles, obtain the longest and shortest diameters of all particles, calculate the ratio of the shortest diameter to the longest diameter of each particle, obtain the sphericity of each particle, and take the average value of the sphericities of all particles to obtain the average sphericity.

[0055] As can be further understood, in the present application, the sphericity of a first silicon-based material refers to the average sphericity of the first silicon-based material, and the sphericity of a second silicon-based material refers to the average sphericity of the second silicon-based material.

[0056] In the present application, some selective examples of the sphericity of the first silicon-based material include a sphericity of 0.6 to 1. For example, the sphericity of the first silicon-based material is 0.6, 0.7, 0.8, 0.9, or 1. If the sphericity of the first silicon-based material is too small, the sphericity of the first silicon-based material is relatively poor, and the first silicon-based material may exhibit relatively sharp corners, thereby increasing the risk of the first silicon-based material damaging the negative electrode current collector during the tableting process. In addition, if the sphericity of the first silicon-based material is too small, the shape of the first silicon-based material is relatively irregular, which may increase the risk of the first silicon-based material being powdered during the tableting process, which may deteriorate the structural stability of the negative electrode plate and further affect the cycle performance of the battery.

[0057] In some embodiments, the sphericity of the second silicon-based material is 0.3 to 0.8. Optionally, the sphericity of the second silicon-based material is 0.3, 0.4, 0.5, 0.6, 0.7, or 0.8. If the sphericity of the second silicon-based material is too small, the shape of the second silicon-based material is relatively irregular, which may increase the risk of the second silicon-based material being powdered during the tableting process, which may deteriorate the structural stability of the negative electrode plate and further affect the cycle performance of the battery. If the sphericity of the second silicon-based material is too large, it may limit the improvement of the compaction density, further limiting the further improvement of the compaction density of the negative electrode plate.

[0058] In some embodiments, the mass percentage of the first silicon-based material in the active material of the first active layer is ≦ the mass percentage of the second silicon-based material in the active material of the second active layer, which effectively achieves both a relatively high energy density and a relatively low expansion coefficient, and is advantageous for allowing the battery to further maintain a relatively high energy density and good cycling performance.

[0059] Optionally, the mass percentage of the first silicon-based material in the active material in the first active layer is ≦15%. If the mass percentage of the first silicon-based material in the active material in the first active layer is too small, there is a limit to improving the energy density of the battery. If the mass percentage of the first silicon-based material in the active material in the first active layer is too large, it may cause a relatively large expansion problem, which is likely to cause problems such as poor battery cycle performance. As some examples of the mass percentage of the first silicon-based material in the active material in the first active layer, the mass percentage of the first silicon-based material in the active material in the first active layer may be 1%, 2%, 5%, 8%, 10%, 12%, 15%, etc.

[0060] Optionally, the mass percentage of the second silicon-based material in the active material in the second active layer is 5% to 40%. If the mass percentage of the second silicon-based material in the active material in the second active layer is too small, it may limit the effective improvement of the battery's energy density. If the mass percentage of the second silicon-based material in the active material in the second active layer is too large, it may cause a relatively large expansion problem, which is likely to cause problems such as poor battery cycle performance. Some examples of the mass percentage of the second silicon-based material in the active material in the second active layer include 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, etc.

[0061] In some embodiments, the first silicon-based material includes oxygen. Optionally, the mass percentage of the oxygen in the first silicon-based material is 40% to 60%. Even more optionally, the mass percentage of the oxygen in the first silicon-based material is 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, or 60%, etc. As can be appreciated, the first silicon-based material is selected from silicon oxide materials.

[0062] In some embodiments, the second silicon-based material includes elemental oxygen. Optionally, the mass percentage of the oxygen element in the second silicon-based material is ≦10%. Even more optionally, the mass percentage of the oxygen element in the second silicon-based material is ≦10%, ≦9%, ≦8%, ≦7%, ≦6%, ≦5%, ≦4%, ≦3%, ≦2%, or ≦1%, etc.

[0063] In some embodiments, the first silicon-based material and the second silicon-based material both contain oxygen, and the mass percentage of the oxygen in the first silicon-based material is greater than the mass percentage of the oxygen in the second silicon-based material, thereby further reducing the expansion rate of the negative electrode plate and maintaining the structural stability during charging.

[0064] In some embodiments, the second silicon-based material does not contain oxygen elements, i.e., the mass percentage of oxygen elements in the second material is 0.

[0065] In some embodiments, the first silicon-based material includes elemental carbon. Optionally, the mass percentage of elemental carbon in the first silicon-based material is ≦8%. Even more optionally, the mass percentage of elemental carbon in the first silicon-based material is ≦7%, ≦6%, ≦5%, ≦4%, ≦3%, ≦2%, or ≦1%, etc. As can be appreciated, the first silicon-based material does not necessarily have to include elemental carbon.

[0066] In some embodiments, the second silicon-based material includes elemental carbon. Optionally, the mass percentage of the carbon element in the second silicon-based material is 40% to 60%. Even more optionally, the mass percentage of the carbon element in the second silicon-based material is 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, or 60%, etc. As can be appreciated, the second silicon-based material is selected from silicon-carbon composites.

[0067] In some embodiments, the first silicon-based material and the second silicon substrate both contain carbon elements, and the mass percentage of the carbon elements in the first silicon-based material in the first silicon-based material is less than the mass percentage of the carbon elements in the second silicon-based material in the second silicon-based material.

[0068] In some embodiments, the first silicon-based material is selected from a silicon oxide material, and the second silicon-based material is selected from a silicon carbon composite.

[0069] In some embodiments, the silicon oxide material can be produced by the following method: S101: Provide silicon and silicon dioxide in a molar ratio of silicon to silicon dioxide of 1:1 to obtain a mixed material. Optionally, metallic magnesium may be further added, and the proportion of the mixed material is 7% to 10% by mass; S102: Using the method of vapor deposition, the mixed material in S101 is heated to 1100 degrees Celsius (°C) to 1500°C to form vapor, and then the vapor is cooled to 700°C to 900°C to form a deposit.

[0070] S103: The deposit is pulverized to obtain a pulverized product of appropriate particle size. The pulverized material is placed in a CVD rotary kiln, an organic gas source is introduced, and the material is deposited at 600°C to 1000°C for 1 hour (h) to 6 hours. The material is then sieved to remove magnetism, and a silicon oxide material is obtained. Optionally, the organic gas source includes a gaseous carbon source. More optionally, the carbon source includes at least one of an alkane and an alkyne.

[0071] Further, optionally, the silicon oxide material obtained in S103 may be subjected to a pre-lithiation treatment.

[0072] Alternatively, a post-coating process may be performed on the silicon oxide material. Alternatively, the post-coating process may be an inorganic coating using salts such as phosphates and / or silicates. The post-coating process may be a liquid-phase coating process.

[0073] In some embodiments, the silicon carbon composite can be produced by the following method: S201: Providing a carbonaceous precursor. The carbonaceous precursor may be at least one of a biomass precursor and a resin precursor. Optionally, the biomass precursor may be at least one of a coconut shell-based biomass and a starch biomass.

[0074] S202: The carbonaceous precursor is carbonized in a nitrogen gas atmosphere at a temperature of 600° C. to 1000° C. for 2 hours to 10 hours to obtain porous carbon.

[0075] S203: The porous carbon is heated in an atmosphere containing a silicon source gas to deposit silicon elemental molecules in the pores of the porous carbon, thereby obtaining a silicon-carbon composite.

[0076] Optionally, the silicon carbon composite obtained in S203 may be subjected to a carbon coating treatment.

[0077] As can be appreciated, silicon oxide materials and silicon carbon composites can also be obtained commercially through commercial channels.

[0078] In some embodiments, the first silicon-based material includes a doping metal element, the doping metal element including at least one of an alkali metal element and an alkaline earth metal element. The introduction of the doping metal element can improve the initial efficiency of the battery. Optionally, the mass percentage of the doping metal element in the first silicon-based material is ≦10%. Even more optionally, the mass percentage of the doping metal element in the first silicon-based material is ≦9%, ≦8%, ≦7%, ≦6%, ≦5%, ≦4%, ≦3%, ≦2%, or ≦1%. As can be appreciated, the alkali metal element includes at least one of lithium, sodium, potassium, rubidium, and cesium. The alkaline earth metal element includes at least one of beryllium, magnesium, calcium, strontium, and barium. Even more optionally, the first silicon-based material includes a pre-lithiated silicon-based material and a pre-magnesiated silicon-based material.

[0079] In some embodiments, the surface of the first silicon-based material is coated with a carbon coating layer, and the coating layer has a thickness of 10 nanometers (nm) to 300 nm. Optionally, the thickness of the carbon coating layer on the surface of the first silicon-based material is 10 nm, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, etc.

[0080] In some embodiments, the surface of the second silicon-based material is coated with a carbon coating layer, and the thickness of the coating layer is 10 nm to 300 nm. Optionally, the thickness of the carbon coating layer on the surface of the second silicon-based material is 10 nm, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, etc.

[0081] In some embodiments, the first active layer further comprises a first graphite, and optionally, the mass percentage of the active material in the first active layer that is the first graphite is ≧85%. Optionally, the mass percentage of the active material in the first active layer that is the first graphite is 85%, 88%, 90%, 92%, 95%, 98%, 99%, etc. Even more optionally, the mass percentage of the active material in the first active layer that is the first graphite is 85%-99%.

[0082] In some embodiments, the second active layer further comprises a second graphite, and optionally the second graphite accounts for 60% to 95% by weight of the active material in the second active layer, or optionally 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, etc.

[0083] As can be understood, the first silicon-based material, the first graphite, the second silicon-based material, the second graphite, the oxygen element in the first silicon-based material, the carbon element in the first silicon-based material, the doping metal element in the first silicon-based material, the oxygen element in the second silicon-based material, and the carbon element in the second silicon-based material can be subjected to cross-sectional polishing (CP) of the negative electrode plate, and the type and content can be detected in combination with a scanning electron microscope (SEM), an electron dispersive spectroscopy (EDS), an inductively coupled plasma spectroscopy (ICP), etc.

[0084] Yet another embodiment of the present application provides a secondary battery, the secondary battery including the negative electrode plate.

[0085] Yet another embodiment of the present application provides a power consuming device, which includes at least one of the negative electrode plate and the secondary battery.

[0086] The secondary battery and power consuming device of the present application will now be described with appropriate reference to the drawings.

[0087] A typical secondary battery includes a positive electrode plate, a negative electrode plate, an electrolyte, and a separator. During charging and discharging, active ions shuttle between the positive and negative electrodes, absorbing and desorbing. The electrolyte serves to conduct ions between the positive and negative electrodes. The separator, located between the positive and negative electrodes, primarily serves to prevent short circuits between the positive and negative electrodes while allowing ions to pass through.

[0088] positive electrode plate The positive electrode plate includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, and the positive electrode film layer includes a positive electrode active material.

[0089] As a non-limiting example, the positive electrode current collector has two surfaces facing each other in the thickness direction thereof, and the positive electrode active material layer is disposed on one or both of the two facing surfaces of the positive electrode current collector.

[0090] In some embodiments, the positive electrode current collector may be a metal foil sheet or a composite current collector. For example, aluminum foil may be used as the metal foil sheet. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. The composite current collector may be obtained by forming a metal material on a polymer substrate. Non-limiting examples of the metal material in the positive electrode current collector may include one or more of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc. Non-limiting examples of the polymer substrate in the positive electrode current collector may include one or more of substrates such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0091] In some embodiments, the positive electrode active material may be a positive electrode active material for batteries known in the art. Non-limiting examples of the positive electrode active material include one or more of the following: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of the lithium transition metal oxide include, but are not limited to, lithium cobalt oxide (e.g., LiCoO), 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 modified compounds thereof. Non-limiting examples of lithium-containing phosphates of the olivine structure may include, but are not limited to, one or more of lithium iron phosphate, lithium iron phosphate and carbon composite, lithium manganese phosphate, lithium manganese phosphate and carbon composite, lithium manganese iron phosphate, lithium manganese iron phosphate and carbon composite, and modified compounds thereof. Non-limiting examples of lithium cobalt oxides may include LiCoO2, non-limiting examples of lithium nickel oxides may include LiNiO2, non-limiting examples of lithium manganese oxides may include LiMnO2, LiMn2O4, etc., and non-limiting examples of lithium nickel cobalt manganese oxides may include LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM 333 (may be abbreviated as "LiNi") 0.5 Co 0.2 Mn 0.3 O2(NCM 523 (may be abbreviated as "LiNi") 0.5 Co 0.25 Mn 0.25 O2(NCM 211 (may be abbreviated as "LiNi") 0.6 Co 0.2 Mn 0.2O2(NCM 622 (may be abbreviated as "LiNi") 0.8 Co 0.1 Mn 0.1 O2(NCM 811 A non-limiting example of lithium nickel cobalt aluminum oxide is LiNi 0.8 Co 0.15 Al 0.05 May contain O2.

[0092] In some embodiments, the positive electrode active material layer may further include an adhesive. Non-limiting examples of the adhesive include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0093] In some embodiments, the positive electrode active material layer may further include a conductive agent, and the conductive agent may include, by way of non-limiting example, one or more of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0094] In some embodiments, a positive electrode plate can be manufactured in the following manner. Components for manufacturing the positive electrode plate, such as a positive electrode active material, a conductive agent, an adhesive, and any other components, are dispersed in a solvent to form a positive electrode slurry. The positive electrode slurry is then applied to at least one surface of a positive electrode current collector, followed by drying, cold pressing, and other processes to obtain a positive electrode plate. The type of solvent may be selected from any one of the above-described embodiments, such as, but not limited to, N-methylpyrrolidone (NMP). The surface of the positive electrode current collector to which the positive electrode slurry is applied may be a single surface of the positive electrode current collector or two surfaces of the positive electrode current collector. The surface of the positive electrode current collector to which the positive electrode slurry is applied may be a single surface of the positive electrode current collector or two surfaces of the positive electrode current collector. The solid content of the positive electrode slurry may be 40 wt% to 80 wt%. The viscosity of the positive electrode slurry at room temperature can be adjusted from 5,000 millipascals per second (mPa·s) to 25,000 mPa·s. When applying the positive electrode slurry, the applied area density (excluding the solvent) is 150 milligrams per square centimeter (mg / m 2 )~350mg / m 2 The positive electrode plate may have a compacted density of 3.0 grams per cubic centimeter (g / cm 3 )~3.6g / cm 3 and optionally 3.3 g / cm 3 ~3.5g / cm 3 may be.

[0095] Negative electrode plate The negative electrode plate 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, and the negative electrode active material layer includes a negative electrode active material.

[0096] As a non-limiting example, the negative electrode current collector has two surfaces facing each other in the thickness direction thereof, and the negative electrode active material layer is disposed on one or both of the two facing surfaces of the negative electrode current collector.

[0097] In some embodiments, the negative electrode current collector may be a metal foil sheet or a composite current collector. For example, copper foil may be used as the metal foil sheet. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be obtained by forming a metal material on a polymer substrate. Non-limiting examples of the metal material in the negative electrode current collector may include one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc. Non-limiting examples of the polymer substrate in the negative electrode current collector may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0098] In some embodiments, the negative electrode active material may be a battery negative electrode active material known in the art. Non-limiting examples of the negative electrode active material include one or more of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. Silicon-based materials may include one or more of silicon elemental, silicon oxide compounds, silicon carbon composites, silicon nitrogen composites, and silicon alloys. Tin-based materials may include one or more of tin elemental, stannate compounds, and tin alloys. However, the present application is not limited to these materials, and other conventional materials that can be used as battery negative electrode active materials may also be used. These negative electrode active materials may be used alone or in combination.

[0099] In some embodiments thereof, the negative electrode active material layer optionally further includes an adhesive, which may include one or more 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).

[0100] In some embodiments, the negative electrode active material layer may further include a conductive agent, which may include one or more of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0101] In some of the embodiments, the negative electrode active material layer optionally further contains other additives, such as a thickener (eg, carboxymethylcellulose sodium (CMC-Na)).

[0102] In some embodiments, a negative electrode plate can be manufactured in the following manner. Components for manufacturing the negative electrode plate, such as a negative electrode active material, a conductive agent, an adhesive, and any other components, are dispersed in a solvent (non-limiting examples of which include deionized water) to form a negative electrode slurry. The negative electrode slurry is then applied to at least one surface of a negative electrode current collector, followed by processes such as drying and cold pressing to obtain a negative electrode plate. The surface of the negative electrode current collector to which the negative electrode slurry is applied may be a single surface of the negative electrode current collector, or may be two surfaces of the negative electrode current collector. The solid content of the negative electrode slurry may be 40 wt% to 60 wt%. The viscosity of the negative electrode slurry at room temperature may be adjusted to 2000 mPa·s to 10000 mPa·s. When the negative electrode slurry is applied, the application unit area density (excluding the solvent) is 75 grams per square meter (g / m) on a dry weight basis. 2 )~220g / m 2 The negative electrode plate may have a compaction density of 1.0 g / cm 3 ~1.8g / cm 3 may be.

[0103] electrolyte The electrolyte serves to conduct ions between the positive and negative electrodes. The present application does not particularly limit the type of electrolyte, and it may be selected according to needs. For example, the electrolyte may be liquid, gel, or all-solid.

[0104] In some embodiments, the electrolyte is an electrolytic solution, which includes an electrolyte salt and a solvent.

[0105] In some embodiments thereof, the electrolyte salt may include one or more of lithium hexafluorophosphate (LiPF), lithium tetrafluoroborate (LiBF), lithium perchlorate (LiClO), lithium hexafluoroarsenate (LiAsF), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorophosphate (LiPOF), lithium difluoro(oxalato)borate (LiDFOB), lithium difluoro(oxalato)borate (LiBOB), lithium difluorobis(oxalato)phosphate (LiDFOP), and lithium tetrafluoro(oxalato)phosphate (LiTFOP).

[0106] In some embodiments thereof, the solvent may include one or more of ethylene carbonate (EC, Formula 1), propylene carbonate (PC, Formula 2), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (Formula 3), fluoroethylene carbonate (FEC), methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, ethyl methyl sulfone, and diethyl sulfone.

[0107] [ka]

[0108] [ka]

[0109] [ka]

[0110] In some embodiments, the electrolyte solution may further optionally contain additives. For example, the additives may include a negative electrode film-forming additive and a positive electrode film-forming additive, and may further include additives that can improve some battery performance, such as an additive that improves battery overcharge performance or an additive that improves battery high-temperature or low-temperature performance.

[0111] In some embodiments, the additives in the electrolyte may include, but are not limited to, one or more of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoromethylethylene carbonate (TFPC), and the like.

[0112] Separator In some embodiments, the secondary battery further includes a separator. The present application does not particularly limit the type of separator, and any known porous separator with good chemical stability and mechanical stability may be selected.

[0113] In some embodiments, the separator may be made of one or more of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film, without any particular limitation. When the separator is a multi-layer composite film, the materials of each layer may be the same or different, without any particular limitation.

[0114] In some embodiments, the thickness of the separator is between 6 micrometers (μm) and 40 μm, optionally between 12 μm and 20 μm.

[0115] In some embodiments, the positive electrode plate, the negative electrode plate, and the separator may be wound or stacked to form an electrode assembly.

[0116] In some embodiments, the secondary battery may include an exterior body, which may be used to package the electrode assembly and the electrolyte.

[0117] In some embodiments, the exterior of the secondary battery may be a hard case, such as a hard plastic case, an aluminum case, a steel case, etc. The exterior of the secondary battery may be a pouch, such as a bag-like pouch. The material of the pouch may be plastic, and non-limiting examples of the plastic may include one or more of polypropylene, polybutylene terephthalate, polybutylene succinate, etc.

[0118] A secondary battery includes at least one battery cell, and may include one or more battery cells.

[0119] In this application, unless otherwise specified, the term "battery cell" refers to a basic unit capable of realizing the mutual conversion of chemical energy and electrical energy, and generally includes at least a positive electrode plate, a negative electrode plate, and an electrolyte. During charging and discharging of the battery, active ions shuttle between the positive electrode plate and the negative electrode plate, absorbing and desorbing. The electrolyte serves to conduct the active ions between the positive electrode plate and the negative electrode plate.

[0120] The present application does not particularly limit the shape of the battery cell, which may be cylindrical, square, or any other shape. For example, Figure 1 shows an example of a battery cell 1 with a square structure.

[0121] In some embodiments, referring to FIG. 2 , the exterior body may include a case 11 and a cover plate 13. Here, the case 11 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and side plate together form a surrounding accommodating cavity. The case 11 has an opening communicating with the accommodating cavity, and the cover plate 13 can be installed to cover the opening to seal the accommodating cavity. The positive electrode plate, the negative electrode plate, and the separator may be formed into an electrode assembly 12 through a winding process or a stacking process. The electrode assembly 12 is packaged in the accommodating cavity. An electrolyte is impregnated into the electrode assembly 12. The number of electrode assemblies 12 included in the battery cell 1 may be one or more, and those skilled in the art can select the number according to actual needs.

[0122] The secondary battery may be a battery module or a battery pack.

[0123] The battery module includes at least one battery cell. The number of battery cells included in the battery module may be one or more, and those skilled in the art may select an appropriate number according to the application and capacity of the battery module.

[0124] In a battery module, the battery cells may be arranged in a row along the length of the battery module, or may be arranged in any other manner. Furthermore, the battery cells may be fastened together by fasteners.

[0125] Optionally, the battery module may further include a housing having an accommodating space, and the plurality of battery cells are accommodated in the accommodating space.

[0126] 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 one or more, and those skilled in the art can select an appropriate number depending on the application and capacity of the battery pack.

[0127] The battery pack may include a battery box and a plurality of battery modules installed in the battery box. The battery box includes an upper housing and a lower housing, and the upper housing may be covered by a lid to form a sealed space for accommodating the battery modules. The plurality of battery modules may be arranged in the battery box in any manner.

[0128] The present application also provides a power consuming device including a secondary battery according to the present application. The secondary battery can be a power source for the power consuming device and can also be an energy storage unit for the power consuming device. The power consuming device may include, but is not limited to, a mobile device, an electric vehicle, an electric train, a ship, a satellite, an energy storage system, etc. Here, the mobile device may be, for example, a mobile phone, a laptop, etc., and the electric vehicle may be, for example, 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, etc., but is not limited to these.

[0129] A secondary battery may be selected as the power consuming device depending on its usage demand.

[0130] 3 shows an example of a power consumption device 2. The power consumption device may be a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, etc. To meet the demand for high power output and high energy density of the secondary battery of the power consumption device, a battery pack or a battery module may be employed.

[0131] Other examples of the device may include a mobile phone, a tablet computer, a laptop computer, etc. These devices are generally required to be thin and lightweight, and may use a secondary battery as a power source.

[0132] In order to make the technical problems, technical solutions, and beneficial effects solved by the present application clearer, the present application will be described in more detail below in conjunction with examples and drawings. Obviously, the described examples are only some of the examples of the present application, but not all of the examples. The following description of at least one exemplary embodiment is merely illustrative in nature and does not constitute any limitation on the present application and its applications. All other embodiments obtained by those skilled in the art based on the examples in the present application without any creative effort fall within the scope of protection of the present application.

[0133] Unless specific techniques or conditions are specified in the examples, they are performed according to the techniques or conditions described in the literature or in accordance with the product instructions. Unless the manufacturer is specified, reagents or equipment used are all commercially available products.

[0134] Secondary battery manufacturing method: (1) Manufacturing of negative electrode plates.

[0135] The first graphite, the first silicon-based material, the conductive agent acetylene black, the thickener sodium carboxymethyl cellulose, and the adhesive styrene butadiene rubber were mixed, and then deionized water was added. After stirring under vacuum, a first slurry having a solids content of 49% was obtained.

[0136] The second graphite, the second silicon-based material, the conductive agent acetylene black, the thickener sodium carboxymethyl cellulose, and the adhesive styrene butadiene rubber were mixed, and then deionized water was added. After stirring under vacuum, a second slurry with a solids content of 49% was obtained.

[0137] The first slurry was applied to a copper foil current collector and dried at 85°C to form a first active layer on the current collector. The second slurry was then applied to the first active layer and dried at 85°C, followed by cold pressing, trimming, slitting, and cutting. Finally, the negative electrode plate was obtained by drying for 12 hours under vacuum at 120°C.

[0138] (2) Manufacturing of positive electrode plates.

[0139] The positive electrode active material NCM, adhesive polyvinylidene fluoride, and conductive agent acetylene black were mixed in a ratio of 97:2:1, and then the solvent N-methylpyrrolidone (NMP) was added and stirred to form a positive electrode slurry. The positive electrode slurry was uniformly applied to a positive electrode current collector aluminum foil, dried, and cold-pressed to obtain a positive electrode plate.

[0140] (3) Electrolyte production.

[0141] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were uniformly mixed in a volume ratio of 20:20:60 to form an organic solvent. LiPF was then dissolved in the organic solvent, and fluoroethylene carbonate (FEC) was added. The concentration of LiPF in the electrolyte was 1 mole / liter (mol / L), and the mass percentage content of FEC was 5 wt%.

[0142] (4) The separator was a Celgard 2400 separator.

[0143] (5) The negative electrode plate, separator, and positive electrode plate were stacked in this order and wound to obtain a wound battery core. The battery core's design capacity was 4.5 ampere-hours (Ah). The battery core was placed in a rectangular aluminum case, dried, and then injected with an electrolyte. After going through processes such as packaging, standing, chemical formation, aging, secondary packaging, and capacity, a secondary battery was obtained.

[0144] The compositions of the negative electrode plates in the examples and comparative examples are as shown in Table 1.

[0145] Test Example (1) Battery energy density test: At 25°C, the manufactured battery was fully discharged at 1 coulomb (C), then fully charged at a rate of 1C, and fully discharged at a rate of 1C, and the actual discharge energy at this time was recorded. At 25°C, the effective length, width, and thickness of the battery core 1C in a fully charged state were measured, and the effective volume V was calculated. The ratio of the actual discharge energy D of the battery 1C to the effective volume V of the battery core was the actual energy density E of the battery, E = D / V, where D is in watt-hours (Wh) and V is in liters (L).

[0146] (2) Stability test of electrode plate structure: The obtained battery was fully charged at 1C, disassembled to obtain the negative electrode plate, folded along the large surface in the horizontal direction, and roll-pressed once along the fold line with a 1 kg standard roll press tool. The folding and roll-pressing operations were repeated three times to check the light transmission or fracture status of the folded electrode plate. The severity was classified into four levels: 1, fracture: electrode plate breakage; 2, serious light transmission: >5 light transmission points; 3, slight light transmission: 1-5 light transmission points; 4, no light transmission.

[0147] (3) Battery cycle performance test: The manufactured battery was cycled at 0.5C / 1C at 25°C to determine the number of cycles at which the battery was attenuated to 80%, i.e., the cycle performance of the corresponding battery.

[0148] (4) Expansion rate test of negative electrode plate: Fresh battery cores after chemical formation were fully charged at 0.33C / 0.33C and then disassembled in a drying room to obtain negative electrode plates. The thickness of the plate in a fully charged state was measured, and the thickness of the plate after cold pressing was compared to calculate the expansion rate. Expansion rate = (thickness of negative electrode plate in a fully charged state - thickness of negative electrode plate after cold pressing) / thickness of negative electrode plate after cold pressing × 100%.

[0149] [Table 1a]

[0150] [Table 1b]

[0151] As can be appreciated, in Table 1, "silicon oxide" refers to silicon oxide material and "silicon carbon" refers to silicon carbon composite. In Table 1, the units of Dv50 are micrometers (μm). The units of specific surface area are square meters per gram (m 2 / g). The unit of the thickness of the first active layer is μm. The unit of the thickness of the second active layer is μm. The unit of the thickness of the carbon coating layer is nm. The unit of the battery energy density is ampere-hours / liter (Wh / L). The unit of the battery cycling performance is cycles. The mass percentage of the first silicon-based material represents the mass percentage of the first silicon-based material in the active material in the first active layer. The mass percentage of the first graphite represents the mass percentage of the first graphite in the active material in the first active layer. The mass percentage of the second silicon-based material represents the mass percentage of the second silicon-based material in the active material in the first active layer. The mass percentage of the second graphite represents the mass percentage of the second graphite in the active material in the second active layer.

[0152] As can be seen from Table 1, when the negative electrode plate contains a silicon-based material, the energy density of the battery is higher. When the sphericity of the first silicon-based material is greater than that of the second silicon-based material, the structural stability of the negative electrode plate is better and the battery has better cycle performance. When the sphericity of the first silicon-based material is less than that of the second silicon-based material, the structural stability of the negative electrode plate is relatively poor and the cycle performance of the battery is correspondingly poor.

[0153] The technical features of the embodiments described above can be combined in any combination. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, any combination should be considered within the scope of the present specification.

[0154] The above examples only show some embodiments of the present application, and although the descriptions are more specific and detailed, they should not be understood as limiting the scope of the invention patent. It should be noted that those skilled in the art can make further modifications and improvements without departing from the concept of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present application patent shall be governed by the appended claims. [Explanation of symbols]

[0155] 1 battery cell 11 cases 12 Electrode Assembly 13 Cover plate 2 Power consumption equipment

Claims

1. a negative electrode plate comprising: a negative electrode current collector; and a first active layer and a second active layer located on at least one surface of the negative electrode current collector, the first active layer being located between the negative electrode current collector and the second active layer, the first active layer comprising a first silicon-based material, and the second active layer comprising a second silicon-based material, the sphericity of the first silicon-based material being greater than the sphericity of the second silicon-based material, the sphericity of the first silicon-based material being 0.6 or greater.

2. The sphericity of the first silicon-based material is between 0.6 and 1; and / or The negative electrode plate according to claim 1, wherein the sphericity of the second silicon-based material is 0.3 to 0.

8.

3. 3. The negative electrode plate according to claim 1, wherein the mass percentage of the first silicon-based material in the active material in the first active layer is less than or equal to the mass percentage of the second silicon-based material in the active material in the second active layer.

4. 4. The negative electrode plate of claim 3, wherein the mass percentage of the first silicon-based material in the active material of the first active layer is ≦15%.

5. The negative electrode plate according to claim 3 or 4, wherein the mass percentage of the second silicon-based material in the active material in the second active layer is 5% to 40%.

6. The negative electrode plate according to any one of claims 1 to 5, wherein Dv50 of the first silicon-based material is less than or equal to Dv50 of the second silicon-based material.

7. The negative electrode plate according to claim 6, wherein the Dv50 of the first silicon-based material is 4 μm to 8 μm.

8. The negative electrode plate according to claim 6 or 7, wherein the Dv50 of the second silicon-based material is 6 μm to 10 μm.

9. The negative electrode plate according to claim 1 , wherein the specific surface area of ​​the first silicon-based material is less than or equal to the specific surface area of ​​the second silicon-based material.

10. The specific surface area of ​​the first silicon-based material is 0.5 m ２ / g to 2.5m ２ The negative electrode plate according to claim 9, wherein the SiO 2 content is 1 / g.

11. The specific surface area of ​​the second silicon-based material is 1 m ２ / g to 4m ２ The negative electrode plate according to claim 9 or 10, wherein the SiO 2 content is 1 / g.

12. The negative electrode plate according to claim 1 , wherein the thickness of the first active layer is greater than or equal to the thickness of the second active layer.

13. The negative electrode plate according to claim 12, wherein the thickness of the first active layer is 20 μm to 40 μm.

14. The negative electrode plate according to claim 12 or 13, wherein the thickness of the second active layer is 20 μm to 40 μm.

15. The negative electrode plate according to claim 1 , wherein the first silicon-based material contains an oxygen element.

16. The negative electrode plate according to claim 14, wherein the mass percentage of oxygen elements in the first silicon-based material is 40% to 60%.

17. The negative electrode plate according to claim 1 , wherein the second silicon-based material contains an oxygen element.

18. 18. The negative electrode plate according to claim 17, wherein a mass percentage of oxygen elements in the second silicon-based material is ≦10%.

19. The negative electrode plate of claim 1 , wherein the first silicon-based material comprises a carbon element.

20. 20. The negative electrode plate according to claim 19, wherein a mass percentage of carbon elements in the first silicon-based material is ≦8%.

21. The negative electrode plate of claim 1 , wherein the second silicon-based material comprises a carbon element.

22. The negative electrode plate according to claim 21, wherein the mass percentage of carbon elements in the second silicon-based material is 40% to 60%.

23. 23. The negative electrode plate of claim 1, wherein the first silicon-based material includes a doping metal element, and the doping metal element includes at least one of an alkali metal element and an alkaline earth metal element.

24. 24. The negative electrode plate of claim 23, wherein the mass percentage of the doping metal element in the first silicon-based material is ≦10%.

25. The negative electrode plate according to any one of claims 1 to 24, wherein a carbon coating layer is coated on a surface of the first silicon-based material and / or a surface of the second silicon-based material.

26. The negative electrode plate according to claim 25, wherein the carbon coating layer has a thickness of 10 nm to 300 nm.

27. 27. The negative electrode plate of claim 1, wherein the first active layer further comprises a first graphite.

28. 28. The negative electrode plate of claim 27, wherein the mass percentage of the first graphite in the active material in the first active layer is ≧85%.

29. 29. The negative electrode plate of any one of claims 1 to 28, wherein the second active layer further comprises a second graphite.

30. The negative electrode plate according to claim 29, wherein the mass percentage of the second graphite in the active material in the second active layer is 60% to 95%.

31. A secondary battery comprising the negative electrode plate according to any one of claims 1 to 30.

32. 32. A power consuming device comprising at least one of the negative electrode plate of any one of claims 1 to 30 and the secondary battery of claim 31.

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