Conductive carbon and preparation method thereof, battery and electric device

Abstract

The invention provides conductive carbon and a preparation method thereof, a battery and a power utilization device, and relates to the field of batteries. The battery comprises conductive carbon, the ID1 / IG1 value of the conductive carbon is 0.2-1.01, and the ID2 / IG2 value of the conductive carbon is 0.3-1.99; wherein ID1 is the peak intensity of a peak D in the Raman spectrum of the conductive carbon, IG1 is the peak intensity of a peak G in the Raman spectrum of the conductive carbon, ID2 is the peak area of the peak D in the Raman spectrum of the conductive carbon, and IG2 is the peak area of the peak G in the Raman spectrum of the conductive carbon. When the conductive carbon is used as a conductive agent to be applied to the cathode piece of the transition metal phosphate series battery with an olivine structure, the defect degree of the conductive carbon is effectively controlled by controlling ID1 / IG1 and ID2 / IG2 in the range, so that the active lithium consumption of the whole cathode piece is reduced, the storage capacity retention rate of the battery is improved, and the storage life is prolonged.

Description

Technical Field

[0001] The present application relates to the field of batteries, and more specifically, to a conductive carbon and a preparation method thereof, a battery, and an electrical device. Background Art

[0002] In recent years, lithium-ion batteries have been widely used in energy storage power systems such as hydropower, thermal, wind and solar power stations, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields, which has put higher requirements on the storage life of lithium-ion batteries.

[0003] Taking lithium-ion batteries whose positive electrode active materials include olivine-structured transition metal phosphate salts (abbreviated as olivine-structured transition metal phosphate salt-based batteries) as an example, they have good thermal stability and excellent charge and discharge cycle performance. However, they have the problem of short storage life during use, which limits their further development. Summary of the Invention

[0004] In view of the above problems, the present application proposes a conductive carbon and a preparation method thereof, a battery and an electrical device, which can improve the technical problem of short battery storage life.

[0005] In a first aspect, an embodiment of the present application provides a battery comprising conductive carbon, wherein the conductive carbon has an ID1 / IG1 value of 0.2-1.01 and an ID2 / IG2 value of 0.3-1.99;

[0006] Among them, ID1 is the peak intensity of the D peak in the Raman spectrum of the conductive carbon, IG1 is the peak intensity of the G peak in the Raman spectrum of the conductive carbon, ID2 is the peak area of ​​the D peak in the Raman spectrum of the conductive carbon, and IG2 is the peak area of ​​the G peak in the Raman spectrum of the conductive carbon.

[0007] The battery provided in the present application controls the ID1 / IG1 and ID2 / IG2 within the above-mentioned range when the above-mentioned conductive carbon is applied as a conductive agent in the negative electrode plate of the olivine-structured transition metal phosphate battery to effectively control the defect degree of the conductive carbon, thereby reducing the active lithium consumption of the entire negative electrode plate, improving the battery storage capacity retention rate, and extending the storage life.

[0008] In some embodiments, the conductive carbon satisfies at least one of (a1)-(a5):

[0009] (a1) The specific surface area of ​​conductive carbon is 50m 2 / g-65m 2 / g;

[0010] (a2) The true density of conductive carbon is 1.90 g / cm 3 -1.98g / cm 3 ;

[0011] (a3) The tap density of conductive carbon is 0.09 g / cm 3 -0.15g / cm 3 ;

[0012] (a4) The ID1 / IG1 value of conductive carbon is 0.3-1.01, and the ID2 / IG2 value is 0.3-1.95;

[0013] (a5) The conductive carbon includes at least one of Super P, acetylene black, and Ketjen black.

[0014] By controlling the parameters and composition of the conductive carbon to be selected within the above range, it is beneficial to apply the above conductive carbon as a conductive agent to the negative electrode plate of an olivine-structured transition metal phosphate battery. This not only reduces the active lithium consumption of the entire negative electrode plate to improve the battery storage capacity retention rate, but also helps to further improve other electrochemical properties of the battery.

[0015] According to some embodiments of the present application, a battery includes a positive electrode plate and a negative electrode plate, the positive electrode plate including a positive electrode active material, the positive electrode active material including an olivine-structured transition metal phosphate salt, and the negative electrode plate including a negative electrode active material and conductive carbon. Since the main problem that causes the short storage life of olivine-structured transition metal phosphate-based batteries originates from the negative electrode side, adding conductive carbon to the negative electrode plate of the olivine-structured transition metal phosphate-based battery is beneficial for reducing the active lithium consumption of the entire negative electrode plate, thereby effectively improving the storage life of the olivine-structured transition metal phosphate-based battery.

[0016] Optionally, the negative electrode active material includes graphite and / or silicon carbon.

[0017] In some embodiments, the olivine-structured transition metal phosphate includes Li α Fe β M 1-β PO4, 0<α≤1.1, 0≤β≤1, M includes one or more of Ti, Mg, Mn, V, Cr, Zr, Nb, and W. When the above-mentioned olivine-structured transition metal phosphate salts are used as the positive electrode active material in a lithium-ion battery and the conductive carbon provided in the present application is used as the conductive agent in the negative electrode plate, it is beneficial to reduce the active lithium consumption of the entire negative electrode plate, thereby effectively improving the storage life of the battery.

[0018] In some embodiments, the olivine-structured transition metal phosphate salt is LiFePO4, LiMnPO4, or a solid solution thereof. LiFePO4 and LiMnPO4, or a solid solution formed by a mixture thereof, are safe and inexpensive, and when used in batteries, can provide the battery with both high cycle life and high stability. Therefore, batteries using the above-mentioned olivine-structured transition metal phosphate salts as the positive electrode active material can achieve high cycle life, high stability, and a long storage life.

[0019] In a second aspect, the present application provides an electrical device, which includes the battery in the above embodiment, and the battery is used to provide electrical energy.

[0020] In a third aspect, the present application also provides a conductive carbon, wherein the conductive carbon has a specific surface area of ​​50m 2 / g-65m 2 / g, ID1 / IG1 value is 0.2-1.01, ID2 / IG2 value is 0.3-1.99;

[0021] Among them, ID1 is the peak intensity of the D peak in the Raman spectrum of the conductive carbon, IG1 is the peak intensity of the G peak in the Raman spectrum of the conductive carbon, ID2 is the peak area of ​​the D peak in the Raman spectrum of the conductive carbon, and IG2 is the peak area of ​​the G peak in the Raman spectrum of the conductive carbon.

[0022] In the technical solution of the embodiment of the present application, by controlling the specific surface area to 50m 2 / g-65m 2 / g of conductive carbon has ID1 / IG1 and ID2 / IG2 within the above ranges, which can effectively control the degree of defects in the conductive carbon, so that when it is used as a conductive agent in the negative electrode sheet of an olivine-structured transition metal phosphate battery, it can reduce the active lithium consumption of the entire negative electrode sheet, thereby improving the battery storage capacity retention rate and extending the storage life.

[0023] In some embodiments, the conductive carbon satisfies at least one of (b1)-(b3):

[0024] (b1) The true density of conductive carbon is 1.90 g / cm 3 -1.98g / cm 3 ;

[0025] (b2) The tap density of conductive carbon is 0.09 g / cm 3 -0.15g / cm 3 ;

[0026] (b3) The ID1 / IG1 value of conductive carbon is 0.3-1.01, and the ID2 / IG2 value is 0.3-1.95.

[0027] By controlling the parameters and composition of the conductive carbon within the above range, it is beneficial to use the above conductive carbon as a conductive agent in the negative electrode of the olivine-structured transition metal phosphate battery, which not only prolongs the storage life but also helps to further improve other electrochemical properties of the battery.

[0028] In some embodiments, the conductive carbon includes at least one of Super P, acetylene black, and Ketjen black. Each of the above conductive carbons has excellent conductivity and a wide range of applications.

[0029] Optionally, the conductive carbon is Super P.

[0030] In a fourth aspect, the present application provides a method for preparing the conductive carbon in the above embodiment, comprising:

[0031] In an inert atmosphere, the raw carbon is heat-treated at 1000° C.-3000° C. for at least 0.5 h to obtain conductive carbon.

[0032] The preparation method provided in the present application is simple and controllable to operate. The defect degree of the conductive carbon can be effectively controlled by the above method, so that when it is used as a conductive agent in the negative electrode sheet of an olivine-structured transition metal phosphate battery, the active lithium consumption of the entire negative electrode sheet can be reduced, thereby improving the battery storage life.

[0033] In some embodiments, the specific surface area of ​​the raw carbon is 50m 2 / g-65m 2 / g, and the ID1 / IG1 value is 1.02-1.45. Using the above raw carbon as raw material and the above preparation method is conducive to obtaining conductive carbon with a reasonable degree of defects and a suitable specific surface area.

[0034] In some embodiments, the heat treatment time is 0.5 h to 6 h. Controlling the heat treatment time within the above range is beneficial for controlling defects in the conductive carbon and keeping the required energy consumption within a reasonable range. When the conductive carbon is used as a conductive agent in the negative electrode of an olivine-structured transition metal phosphate-based battery, it is beneficial for reducing the active lithium consumption of the entire negative electrode and improving the battery storage life.

[0035] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0037] Figure 1 A schematic structural diagram of a vehicle according to some embodiments of the present application;

[0038] Figure 2 Schematic diagram of the exploded structure of batteries according to some embodiments of the present application;

[0039] Figure 3 This is a schematic diagram of the exploded structure of a battery cell according to some embodiments of the present application;

[0040] Figure 4 Graph showing the storage capacity change of the lithium-ion batteries in Examples 1-3 and Comparative Example 1.

[0041] The accompanying drawings in the specific implementation manner are as follows:

[0042] 1000-vehicles;

[0043] 100-battery; 200-controller; 300-motor;

[0044] 10- box body; 11- first part; 12- second part;

[0045] 20 - battery cell; 21 - housing; 22 - electrode assembly; 23 - electrode terminal; 24 - pressure relief structure;

[0046] 211-shell; 212-cover. DETAILED DESCRIPTION

[0047] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0049] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0050] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0051] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0052] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0053] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0054] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0055] In recent years, lithium-ion batteries have been widely used. Taking batteries whose positive electrode active materials include olivine-structured transition metal phosphate salts (hereinafter referred to as olivine-structured transition metal phosphate salt-based batteries) as an example, they have good thermal stability and excellent charge and discharge cycle performance. However, there is a problem of short storage life during their use, which limits their further development.

[0056] Among them, the main problem that leads to the short storage life of olivine-structured transition metal phosphate batteries comes from the negative electrode side. Therefore, the current directions for improving the storage life of olivine-structured transition metal phosphate batteries are mainly (1) modification of the negative electrode active material, (2) artificial SEI, and (3) modification of the electrolyte.

[0057] Considering that the negative electrode sheet includes not only the negative electrode active material, but also conductive carbon and binder, the specific surface area of ​​conductive carbon is generally higher than that of graphite (specific surface area ~1-3m 2 / g), which means that compared with graphite, conductive carbon has abundant pores. The richer the pores of carbon materials, the more defects and oxygen-containing functional groups there are, which causes the battery to consume more active lithium during storage, thus affecting the battery storage life.

[0058] Therefore, based on the above considerations, in order to improve the problem of short battery storage life, the present application provides a battery comprising conductive carbon, wherein the ID1 / IG1 value of the conductive carbon is 0.2-1.01, and the ID2 / IG2 value is 0.3-1.99;

[0059] Among them, ID1 is the peak intensity of the D peak in the Raman spectrum of the conductive carbon, IG1 is the peak intensity of the G peak in the Raman spectrum of the conductive carbon, ID2 is the peak area of ​​the D peak in the Raman spectrum of the conductive carbon, and IG2 is the peak area of ​​the G peak in the Raman spectrum of the conductive carbon.

[0060] The battery provided in the present application controls the ID1 / IG1 and ID2 / IG2 within the above-mentioned range when the above-mentioned conductive carbon is applied as a conductive agent in the negative electrode plate of the olivine-structured transition metal phosphate battery to effectively control the defect degree of the conductive carbon, thereby reducing the active lithium consumption of the entire negative electrode plate, improving the battery storage capacity retention rate, and extending the storage life.

[0061] The batteries disclosed in the embodiments of this application can be power batteries or energy storage batteries. Application scenarios for power batteries include, but are not limited to, vehicles, ships, aircraft, spacecraft, power tools, electric toys, various mobile terminals, and the like. Application scenarios for energy storage batteries include, but are not limited to, solar power generation systems, hydropower generation systems, wind power generation systems, and the like. All of these are beneficial for alleviating and improving battery performance and for extending the storage life of olivine-structured transition metal phosphate-based batteries.

[0062] The present invention provides an electric device that uses a battery as a power source. The electric device may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery-powered vehicle, an electric car, a ship, a spacecraft, etc. The electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc. The spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0063] For the convenience of description, the following embodiments are described by taking a vehicle 1000 as an example of an electrical device according to an embodiment of the present application.

[0064] Please refer to Figure 1 , Figure 1 A schematic structural diagram of a vehicle 1000 provided for some embodiments of the present application. The vehicle 1000 may be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000. The battery 100 may be provided at the bottom, head or tail of the vehicle 1000. The battery 100 may be used to power the vehicle 1000. For example, the battery 100 may serve as an operating power source for the vehicle 1000. The vehicle 1000 may further include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to power the motor 300, for example, to meet the power requirements for starting, navigating and driving the vehicle 1000.

[0065] In some embodiments of the present application, the battery 100 can serve not only as an operating power source for the vehicle 1000, but also as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0066] In this application, the battery 100 refers to a single physical module that includes one or more battery cells 20 to provide a certain voltage and capacity. It can be in the form of a battery pack, a battery module, etc. The battery 100 may also include a box 10 for encapsulating one or more battery cells 20. The box 10 can prevent liquid or other foreign matter from affecting the charging or discharging of the battery cells 20.

[0067] Please refer to Figure 2 , Figure 2An exploded view of a battery 100 provided in some embodiments of the present application. The battery 100 includes a housing 10 and battery cells 20, with the battery cells 20 housed within the housing 10. The housing 10 is used to provide a storage space for the battery cells 20 and can have various structures. In some embodiments, the housing 10 can include a first portion 11 and a second portion 12, which overlap each other and together define a storage space for the battery cells 20. The second portion 12 can be a hollow structure with one end open. The first portion 11 can be a plate-like structure, with the first portion 11 overlapping the open side of the second portion 12, so that the first portion 11 and the second portion 12 together define a storage space. The first portion 11 and the second portion 12 can also be hollow structures with one end open, with the open side of the first portion 11 overlapping the open side of the second portion 12. Of course, the housing 10 formed by the first portion 11 and the second portion 12 can have various shapes, such as a cylinder, a rectangular parallelepiped, etc.

[0068] In the battery 100, there may be multiple battery cells 20, and the multiple battery cells 20 may be connected in series, in parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 20. The multiple battery cells 20 may be directly connected in series, in parallel, or in a hybrid connection, and then the entire battery cell 20 may be housed within the housing 10. Alternatively, the battery 100 may be constructed by first connecting multiple battery cells 20 in series, in parallel, or in a hybrid connection to form a battery module, which is then connected in series, in parallel, or in a hybrid connection to form a complete battery module, and then housed within the housing 10. The battery 100 may also include other structures, such as a busbar assembly for electrically connecting the multiple battery cells 20.

[0069] The battery cell 20 refers to the smallest unit constituting the battery 100 .

[0070] Please refer to Figure 3 , Figure 3 This is a schematic diagram of the exploded structure of the battery cell 20 provided in some embodiments of the present application. Figure 3 The battery cell 20 may include a housing 21 , an electrode assembly 22 and an electrolyte, and both the electrode assembly 22 and the electrolyte are contained in the housing 21 .

[0071] The outer shell 21 may include a shell 211 and a cover 212. The shell 211 is a component used to cooperate with the cover 212 to form an internal sealed space of the battery cell 20, wherein the formed sealed space can be used to accommodate the electrode assembly 22, electrolyte and other components. The cover 212 refers to a component that covers the opening of the shell 211 to isolate the internal environment of the battery cell 20 from the external environment. The shape of the cover 212 can be adapted to the shape of the shell 211 to cooperate with the shell 211. Functional components such as electrode terminals 23 and pressure relief structures 24 can also be provided on the cover 212. A sealing ring can be configured between the opening of the shell 211 and the cover 212 to achieve sealing between the shell 211 and the cover 212.

[0072] The shell 211 and the cover 212 can be of various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shapes of the shell 211 and the cover 212 can be determined according to the specific shape and size of the electrode assembly 22. The material of the shell 211 and the cover 212 can be various, such as but not limited to metals such as copper, iron, aluminum, stainless steel, and aluminum alloy. The material of the sealing ring can be various, such as but not limited to PP (polypropylene), PC (polycarbonate), PET (polyethylene terephthalate) and other materials that are resistant to electrolyte corrosion, high toughness and fatigue resistance. A coating can be formed on the outer surface of the shell 211, and the material of the coating can be various, such as but not limited to corrosion-resistant materials such as Ni and Cr.

[0073] The battery cell 20 may also be in the form of a soft pack, such as a pouch-type soft pack. The soft pack may be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0074] The electrode assembly 22 includes a negative electrode sheet, a separator, and a positive electrode sheet. The battery cell 20 primarily operates by the movement of metal ions between the positive and negative electrode sheets. During the charge and discharge process, active ions are embedded in and released from the positive and negative electrode sheets. The separator, located between the positive and negative electrode sheets, primarily prevents short circuits between the positive and negative electrodes while allowing ions to pass through. The electrode assembly 22 can be a wound or laminated structure, but the embodiments of the present application are not limited thereto.

[0075] The positive electrode sheet includes a positive electrode current collector, a positive electrode tab, and a positive electrode active material layer. The positive electrode active material layer is disposed on at least one side of the positive electrode current collector and includes a positive electrode active material. A primer layer or the like may be disposed between the positive electrode active material layer and the positive electrode current collector. The positive electrode tab protrudes from the positive electrode current collector and is located, for example, at one end or two opposing ends of the positive electrode current collector.

[0076] The positive electrode current collector may be a metal foil or a composite current collector. For example, the material of the positive electrode current collector and the positive electrode tab may be aluminum. The composite current collector may include a polymer material base layer and a metal layer formed on at least one side of the polymer material base layer. 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 made of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0077] 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), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0078] In some embodiments, the positive electrode active material layer may further include a conductive agent. For example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0079] The isolation membrane is located between the positive electrode sheet and the negative electrode sheet and serves as an isolation membrane. The embodiment of the present application has no particular restriction on the type of isolation membrane, and any well-known porous structure isolation membrane with good chemical stability and mechanical stability can be selected.

[0080] In some embodiments, the material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0081] The negative electrode sheet includes a negative electrode current collector, a negative electrode tab, and a negative electrode active material layer. The negative electrode active material layer is disposed on at least one side of the negative electrode current collector and includes a negative electrode active material. A primer layer or the like may be disposed between the negative electrode current collector and the negative electrode active material layer. The negative electrode tab protrudes from the negative electrode current collector and is located, for example, at one end or two opposing ends of the negative electrode current collector.

[0082] Among them, the negative electrode current collector can be a metal foil or a composite current collector. For example, the material of the negative electrode current collector and the negative electrode tab can be copper. The composite current collector may include a polymer material base layer and a metal layer formed on at least one side of the polymer material substrate. The composite current collector can 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 polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0083] In some embodiments, the negative electrode active material layer may further include a conductive agent. For example, the conductive agent may include at least one of acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, and carbon nanofibers.

[0084] 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).

[0085] 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)).

[0086] According to some embodiments of the present application, the battery includes conductive carbon, and the conductive carbon has an ID1 / IG1 value of 0.2-1.01 and an ID2 / IG2 value of 0.3-1.99;

[0087] Among them, ID1 is the peak intensity of the D peak in the Raman spectrum of the conductive carbon, IG1 is the peak intensity of the G peak in the Raman spectrum of the conductive carbon, ID2 is the peak area of ​​the D peak in the Raman spectrum of the conductive carbon, and IG2 is the peak area of ​​the G peak in the Raman spectrum of the conductive carbon.

[0088] Both D peak and G peak are Raman characteristic peaks of carbon atom crystals. The D peak has a Raman shift of 1328-1359 cm -1 The scattering peak at the G peak is Raman shifted at 1578-1585 cm -1 ID1 / IG1 and ID2 / IG2 both characterize the degree of defects in the conductive carbon. The larger the ratio of ID1 / IG1 and ID2 / IG2, the greater the degree of defects.

[0089] The battery provided in the present application, by applying the above-mentioned conductive carbon as a conductive agent in the negative electrode plate of the olivine-structured transition metal phosphate battery, by controlling its ID1 / IG1 and ID2 / IG2 within the above-mentioned range to effectively control the defect degree of the conductive carbon, thereby reducing the active lithium consumption of the entire negative electrode plate, improving the battery storage capacity retention rate, and extending the storage life.

[0090] The conductive carbon includes at least one of carbon nanofibers, carbon dots, graphene and carbon black, and the carbon black includes but is not limited to at least one of carbon black Super P, acetylene black, Ketjen black, channel black, furnace black, lamp black and thermal black.

[0091] According to some embodiments of the present application, the conductive carbon satisfies at least one of (a1)-(a5):

[0092] (a1) The specific surface area of ​​conductive carbon is 50m 2 / g-65m 2 / g.

[0093] Since the conductive carbon has a porous structure, it can produce a certain adsorption effect on the electrolyte. Therefore, under the premise that the ID1 / IG1 value of the conductive carbon is 0.2-1.01 and the ID2 / IG2 value is 0.3-1.99, its specific surface area is further controlled within the above range. On the premise of reducing the defects of the conductive carbon, the specific surface area of ​​the conductive carbon can be further controlled within the above range to control its pore structure. When it is used as a conductive agent in the negative electrode sheet of an olivine-structured transition metal phosphate battery, it can not only improve the battery storage life, but also help to improve the infiltration of the electrolyte, indirectly increase the transmission rate of lithium ions, and improve the electrochemical performance of the battery.

[0094] For example, the specific surface area of ​​the conductive carbon is 50 m 2 / g、55m 2 / g, 60m 2 / g、65m 2 / g, any value in, or between any two values.

[0095] Optionally, the conductive carbon has a specific surface area of ​​53 m 2 / g-65m 2 / g.

[0096] For example, the specific surface area of ​​conductive carbon is 53m 2 / g、55m 2 / g、57m 2 / g, 60m 2 / g、63m 2 / g、65m 2 Any value in / g or between any two values.

[0097] (a2) The true density of conductive carbon is 1.90 g / cm 3 -1.98g / cm 3 ;

[0098] Under the premise that the ID1 / IG1 value of the conductive carbon is 0.2-1.01 and the ID2 / IG2 value is 0.3-1.99, its true density is controlled within the above range, so that the conductive carbon can have better conductivity and specific surface area while improving surface defects, which is beneficial to improving the electrochemical performance of the battery.

[0099] For example, the true density of conductive carbon is 1.900 g / cm 3 、1.910g / cm 3 , 1.920g / cm 3 , 1.925g / g / cm 3 、1.930g / cm 3 , 1.935g / cm 3 、1.940g / cm 3 , 1.945g / cm 3 , 1.950g / g / cm 3 , 1.960g / cm 3 、1.970g / cm 3 、1.980g / cm 3 Any value in or between any two values.

[0100] (a3) The tap density of conductive carbon is 0.09 g / cm 3 -0.15g / cm 3 ;

[0101] By controlling the tap density within the above range, there is a certain porosity between the conductive carbon particles, so that when it is used as a conductive agent in a battery, it can promote the movement of ions in the electrolyte between electrodes and improve the electrochemical performance of the battery.

[0102] For example, the tap density of the conductive carbon is 0.09 g / cm 3 , 0.10g / cm 3 , 0.11g / cm 3 , 0.12g / g / cm 3 , 0.15g / cm 3 Any value in or between any two values.

[0103] (a4) The ID1 / IG1 value of conductive carbon is 0.3-1.01, and the ID2 / IG2 value is 0.3-1.95;

[0104] Controlling the ID1 / IG1 value and ID2 / IG2 value of the conductive carbon within the above range is beneficial to controlling the degree of defects on the surface of the conductive carbon, so that when it is used as a conductive agent in the negative electrode sheet of an olivine-structured transition metal phosphate battery, it can reduce the active lithium consumption of the entire negative electrode sheet, thereby improving the battery storage capacity retention rate and extending the storage life.

[0105] (a5) The conductive carbon includes at least one of Super P, acetylene black, and Ketjen black.

[0106] The above-mentioned conductive carbons have excellent electrical conductivity and a wide range of applications. They can directly participate in the construction of short- and long-range conductive networks in lithium-ion batteries, significantly improving the electrical performance of the batteries. In addition, the above-mentioned conductive carbons also have a relatively high specific surface area, which can improve the infiltration of the electrolyte, indirectly increase the transmission rate of lithium ions, and improve the electrical performance of the batteries.

[0107] Optionally, the conductive carbon is Super P.

[0108] Among them, Super P has excellent conductivity, is easy to obtain and has high cost performance, which can reduce preparation costs.

[0109] According to some embodiments of the present application, the battery includes a positive electrode sheet and a negative electrode sheet, the positive electrode sheet includes a positive electrode active material, the positive electrode active material includes an olivine-structured transition metal phosphate, and the negative electrode sheet includes a negative electrode active material and conductive carbon.

[0110] Since the main problem that leads to the short storage life of olivine-structured transition metal phosphate batteries comes from the negative electrode side, adding conductive carbon to the negative electrode plate of the olivine-structured transition metal phosphate battery is beneficial to reduce the active lithium consumption of the entire negative electrode plate, thereby effectively improving the storage life of the olivine-structured transition metal phosphate battery.

[0111] Optionally, the negative electrode active material includes graphite and / or silicon carbon.

[0112] The above-mentioned negative electrode active material is highly safe and easy to industrialize, and its specific surface area is much smaller than that of conductive carbon, which can alleviate the consumption of active lithium during storage.

[0113] According to some embodiments of the present application, the olivine-structured transition metal phosphate includes Li α Fe β M 1-β PO4, 0<α≤1.1, 0≤β≤1, M includes one or more of Ti, Mg, Mn, V, Cr, Zr, Nb, and W.

[0114] When the above-mentioned olivine-structured transition metal phosphate salts are used as the positive electrode active material in a lithium-ion battery and the conductive carbon provided in this application is used as the conductive agent in the negative electrode plate, it is beneficial to reduce the active lithium consumption of the entire negative electrode plate, thereby effectively improving the storage life of the battery.

[0115] It should be noted that the above-mentioned olivine-structured transition metal phosphate includes but is not limited to the components shown in the above examples.

[0116] 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 enumeration of phosphate transition metal salts with an olivine structure in this application, the molar content of Li is the initial state of the material, that is, the state before feeding. The phosphate transition metal salt with an olivine structure is applied to the battery system, and after the charge and discharge cycle, the molar content of Li will change. In the enumeration of phosphate transition metal salts with an olivine structure in this application, the molar content of O is only a theoretical state value. Lattice oxygen release will cause the molar content of oxygen to change, and the actual molar content of O will fluctuate.

[0117] According to some embodiments of the present application, the olivine-structured transition metal phosphate salt is LiFePO 4 , LiMnPO 4 , and a solid solution thereof.

[0118] The solid solution of LiFePO4 and LiMnPO4 refers to LiFe α M 1-α PO4 (lithium manganese iron phosphate, LMFP).

[0119] Among them, LiFePO4 and LiMnPO4 or the solid solution formed by their mixture is safe and cheap, and after being applied to batteries, the batteries can have high cycle and high stability. Therefore, batteries using the above-mentioned olivine-structured transition metal phosphate as the positive electrode active material can have high cycle, high stability and long storage life.

[0120] According to some embodiments of the present application, the present application further provides an electrical device, comprising a battery according to any of the above solutions, and the battery is used to provide electrical energy to the electrical device.

[0121] The power-consuming device may be any of the aforementioned devices or systems using batteries.

[0122] According to some embodiments of the present application, the present application also provides a conductive carbon, wherein the specific surface area of ​​the conductive carbon is 50m 2 / g-65m 2 / g, ID1 / IG1 value is 0.2-1.01, and ID2 / IG2 value is 0.3-1.99.

[0123] Among them, ID1 is the peak intensity of the D peak in the Raman spectrum of the conductive carbon, IG1 is the peak intensity of the G peak in the Raman spectrum of the conductive carbon, ID2 is the peak area of ​​the D peak in the Raman spectrum of the conductive carbon, and IG2 is the peak area of ​​the G peak in the Raman spectrum of the conductive carbon.

[0124] Both D peak and G peak are Raman characteristic peaks of carbon atom crystals. The D peak has a Raman shift of 1328-1359 cm -1 The scattering peak at the G peak is Raman shifted at 1578-1585 cm -1 ID1 / IG1 and ID2 / IG2 both characterize the degree of defects in the conductive carbon. The larger the ratio of ID1 / IG1 and ID2 / IG2, the greater the degree of defects.

[0125] The specific surface area has a well-known meaning in the art and can be measured using instruments and methods known in the art. For example, it can be measured using a nitrogen adsorption specific surface area analysis method and calculated using the BET method.

[0126] The conductive carbon provided by this application is controlled to have a specific surface area of ​​50m 2 / g-65m 2 / g of conductive carbon has ID1 / IG1 and ID2 / IG2 within the above ranges, effectively controlling the degree of defects in the conductive carbon so that it can be directly used as a conductive agent in the negative electrode of an olivine-structured transition metal phosphate battery, thereby reducing the active lithium consumption of the entire negative electrode, thereby improving the battery storage capacity retention rate and extending the storage life.

[0127] For example, the specific surface area of ​​the conductive carbon is 50 m 2 / g、53m 2 / g、55m 2 / g、58m 2 / g, 60m 2 / g、63m 2 / g、65m 2 Any value in / g or between any two values. Optional is 53m 2 / g-65m 2 / g.

[0128] Exemplarily, the ID1 / IG1 value of the conductive carbon is any one of 0.2, 0.3, 0.5, 0.7, 1.0, 1.01, or between any two values.

[0129] Illustratively, the ID2 / IG2 value of the conductive carbon is any one of 0.3, 0.5, 0.7, 1.0, 1.2, 1.5, 1.98, 1.99, or between any two values.

[0130] In some optional embodiments, the conductive carbon satisfies at least one of (b1)-(b3):

[0131] (b1) The true density of conductive carbon is 1.90 g / cm 3 -1.98g / cm 3 ;

[0132] Under the premise that the ID1 / IG1 value of the conductive carbon is 0.2-1.01 and the ID2 / IG2 value is 0.3-1.99, its true density is controlled within the above range, so that the conductive carbon can have better conductivity and specific surface area while improving surface defects, which is beneficial to improving the electrochemical performance of the battery.

[0133] For example, the true density of conductive carbon is 1.900 g / cm 3 , 1.920g / cm 3 , 1.925g / g / cm 3 、1.930g / cm 3 , 1.935g / cm 3 、1.940g / cm 3 , 1.945g / cm 3 , 1.950g / g / cm 3 、1.980g / cm 3 Any value in or between any two values.

[0134] (b2) The tap density of conductive carbon is 0.09 g / cm 3 -0.15g / cm 3 ;

[0135] By controlling the tap density within the above range, there is a certain porosity between the conductive carbon particles, so that when it is used as a conductive agent in a battery, it can promote the movement of ions in the electrolyte between electrodes and improve the electrochemical performance of the battery.

[0136] For example, the tap density of the conductive carbon is 0.09 g / cm 3 , 0.10g / cm 3 , 0.11g / cm 3 , 0.12g / g / cm 3 , 0.15g / cm 3 Any value in or between any two values.

[0137] (b3) The ID1 / IG1 value of conductive carbon is 0.3-1.01, and the ID2 / IG2 value is 0.3-1.95.

[0138] Controlling the ID1 / IG1 value and ID2 / IG2 value of the conductive carbon within the above range is beneficial to controlling the degree of defects on the surface of the conductive carbon, so that when it is used as a conductive agent in the negative electrode sheet of an olivine-structured transition metal phosphate battery, it can reduce the active lithium consumption of the entire negative electrode sheet, thereby improving the battery storage capacity retention rate and extending the storage life.

[0139] The conductive carbon includes at least one of carbon nanofibers, carbon dots, graphene and carbon black, and the carbon black includes but is not limited to at least one of carbon black Super P, acetylene black, Ketjen black, channel black, furnace black, lamp black and thermal black.

[0140] In some optional embodiments, the conductive carbon includes at least one of Super P, acetylene black, and Ketjen black.

[0141] The above-mentioned conductive carbons have excellent electrical conductivity and a wide range of applications. They can directly participate in the construction of short- and long-range conductive networks in lithium-ion batteries, significantly improving the electrical performance of the batteries. In addition, the above-mentioned conductive carbons also have a relatively high specific surface area, which can improve the infiltration of the electrolyte, indirectly increase the transmission rate of lithium ions, and improve the electrical performance of the batteries.

[0142] Optionally, the conductive carbon is Super P.

[0143] Among them, Super P has excellent conductivity, is easy to obtain and has high cost performance, which can reduce preparation costs.

[0144] According to some embodiments of the present application, the present application further provides a method for preparing the above-mentioned conductive carbon, which comprises:

[0145] In an inert atmosphere, the raw carbon is heat-treated at 1000° C.-3000° C. for at least 0.5 h to obtain conductive carbon.

[0146] Raw carbon refers to a carbon material that has not been processed by this application, that is, the raw carbon is the carbon material before the above-mentioned heat treatment. Raw carbon includes but is not limited to Super P, acetylene black, Ketjen black, carbon nanofiber, etc. It is understandable that the raw carbon and the final conductive carbon are of the same type, and heat treatment does not change their types, that is, the raw carbon is acetylene black, and the conductive carbon obtained by heat treatment is also acetylene black. The raw carbon can be purchased directly on the market or prepared by itself. For example, the preparation steps of raw carbon include but are not limited to: the raw material containing the carbon source (such as petroleum asphalt, natural rubber, coal, polymer, etc.) is subjected to pre-treatment processes such as odor removal, dehydration, filtration, and drying, and then placed in an electric furnace or kiln, heated to 500°C-900°C for heat preservation and pyrolysis, and the carbon black obtained after the pyrolysis is used as the raw carbon.

[0147] ID1 is the peak intensity of the D peak in the Raman spectrum of the conductive carbon, and IG1 is the peak intensity of the G peak in the Raman spectrum of the conductive carbon. It can be understood that the above-mentioned high-temperature heat treatment can effectively reduce the degree of surface defects, that is, the ID1 / IG1 value and ID2 / IG2 value of the conductive carbon are greater than the ID1 / IG1 value and ID2 / IG2 value of the raw carbon before the high-temperature heat treatment of the conductive carbon.

[0148] Inert atmospheres include nitrogen and / or argon.

[0149] Controlling the raw carbon to be heat-treated at 1000°C-3000°C for at least 0.5h under an inert atmosphere is beneficial for controlling the defect level of the conductive carbon within a reasonable range. When the conductive carbon is used as a conductive agent in the negative electrode of an olivine-structured transition metal phosphate battery, it can reduce the active lithium consumption of the entire negative electrode, thereby improving the battery storage life. Exemplarily, the heat treatment temperature is any value of 1000°C, 1150°C, 1300°C, 1500°C, 1700°C, 2000°C, 2300°C, 2500°C, 2800°C, 3000°C, or between any two values.

[0150] In summary, the preparation method provided in the present application is simple and controllable to operate. The defect degree of the conductive carbon can be effectively controlled by the above method, so that when it is used as a conductive agent in the negative electrode of the olivine-structured transition metal phosphate battery, the active lithium consumption of the entire negative electrode can be reduced, thereby improving the battery storage life.

[0151] It can be understood that the conductive carbon prepared by the preparation method provided in the present application can effectively reduce the defects, oxygen-containing functional groups and dangling bonds of the conductive carbon through high-temperature heat treatment, and inactivate the raw carbon, thereby reducing the active lithium consumption of the entire negative electrode when it is used in an olivine-structured transition metal phosphate battery. Therefore, its true density is lower than that of the corresponding raw carbon, and its tap density is higher than that of the corresponding raw carbon.

[0152] It should be noted that the preparation method of the conductive carbon includes but is not limited to the above-mentioned heat treatment method, and can also be laser radiation heat treatment and other methods.

[0153] According to some embodiments of the present application, the specific surface area of ​​the raw carbon is 50m 2 / g-65m 2 / g, ID1 / IG1 value is 1.02-1.45.

[0154] The specific surface area of ​​the raw carbon within the above range is conducive to controlling the specific surface area of ​​the conductive carbon to meet relevant requirements through heat treatment, and can also mitigate significant changes in wettability caused by significant changes in specific surface area, which can affect the electrochemical performance of the battery. Furthermore, the ID1 / IG1 value of the raw carbon within the above range is also conducive to controlling defects in the conductive carbon to meet relevant requirements through heat treatment.

[0155] In some optional embodiments, the heat treatment time is 0.5h-6h.

[0156] Controlling the heat treatment temperature and / or time within the above range is beneficial to controlling the defects of the conductive carbon and the required energy consumption within a reasonable range, so that when it is used as a conductive agent in the negative electrode sheet of an olivine-structured transition metal phosphate battery, it is beneficial to reduce the active lithium consumption of the entire negative electrode sheet and improve the battery storage life.

[0157] If the heat treatment time is too short, the defects of the raw carbon cannot be effectively improved. If the heat treatment time is too long, the production cost will increase. Therefore, controlling the heat treatment time to 0.5h-6h is beneficial to controlling the defects of the conductive carbon and keeping the required energy consumption within a reasonable range. For example, the heat treatment time is any value of 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h or between any two values.

[0158] Some specific embodiments are listed below to better illustrate the present application.

[0159] Example 1

[0160]

Raw carbon

[0161] Super P, with a specific surface area of ​​61.4m 2 / g, ID1 / IG1 value is 1.02, ID2 / IG2 value is 2.01, and true density is 1.978g / cm 3 , the tap density is 0.07g / cm 3 .

[0162]

Conductive carbon

[0163] In a nitrogen atmosphere, the raw carbon was kept at 1150°C for 4 hours and naturally cooled to obtain conductive carbon.

[0164]

Positive electrode

[0165] Lithium iron phosphate, conductive agent carbon black (Super P, the above-mentioned raw carbon), and binder PVDF were thoroughly stirred and mixed in an appropriate amount of N-methylpyrrolidone (NMP) at a weight ratio of 97.2:0.7:2.1 to form a uniform positive electrode slurry; the positive electrode slurry was applied to the surface of the positive electrode current collector aluminum foil, and then dried, cold pressed, slit, and cut to obtain the positive electrode sheet. The compacted density of the positive electrode sheet is 2.45g / cm 3 , the surface density is 21.68mg / cm 2 .

[0166]

Negative electrode

[0167] The negative electrode active material artificial graphite, the above-mentioned conductive carbon, the thickener sodium carboxymethyl cellulose (CMC), and the binder were mixed in a mass ratio of 96.82:0.53:0.7:1.95, and deionized water was added as a solvent. The mixture was stirred under the action of a vacuum mixer until the system was uniform. The mixture was evenly coated on both surfaces of a negative electrode current collector copper foil with a thickness of 6 μm, and dried at 110°C for 20 min. After drying, the electrode was cold pressed to obtain a coating weight of 10.71 mg / cm2 and a compaction density of 1.4 g / cm 3 , the negative electrode plate has a thickness of 159um.

[0168]

Isolation film

[0169] A polyethylene film with a thickness of 12 μm was selected as the isolation film.

[0170] [Electrolyte]

[0171] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1 to obtain an organic solvent. Fully dried lithium salt LiPF6 is dissolved in the organic solvent to a concentration of 1 mol / L. The mixture is mixed evenly to obtain an electrolyte.

[0172] Lithium-ion battery

[0173] The positive electrode sheet, separator, and negative electrode sheet prepared above are stacked in sequence, with the separator placed between the positive and negative electrodes to play an isolating role, and then wound to obtain an electrode assembly; the electrode assembly is placed in an outer package, injected with the prepared electrolyte and packaged, and a lithium-ion battery is obtained through a process of formation, degassing, and trimming.

[0174] Examples 2-8 and Comparative Examples 1-2

[0175] The only differences between each embodiment and comparative example and embodiment 1 are shown in Table 1.

[0176] In comparative example 1, untreated raw carbon was directly used as conductive carbon.

[0177] The only difference between Comparative Example 2 and Example 1 is that the raw carbon is heat treated at 500° C. for 1 h.

[0178] Test example

[0179] The conductive carbon and the battery in each embodiment and comparative example 1 were tested, wherein the testing method is as follows:

[0180] 1. Specific surface area test method:

[0181] The specific surface area is tested using the national standard: GB / T19587-2004, "Determination of specific surface area of ​​solid substances by gas adsorption BET method".

[0182] 2. Test methods for ID2 / IG2 and ID1 / IG1:

[0183] Conductive carbon was placed on a glass slide. An area of ​​140 μm × 140 μm was selected on the surface of the conductive carbon layer. The particles within the area were scanned using a laser microconfocal Raman spectrometer (Raman, HR Evolution, HORIBA Scientific Instruments Division). The D peak and G peak of all particles within the area were obtained, where the D peak appeared at 1328-1359 cm -1 ; G peak appears at 1578-1585cm -1 ; The data were processed using LabSpec software to obtain the peak intensities of the D peak and G peak of each particle, which were ID1 and IG1 respectively. The data were processed using LabSpec software to obtain the peak areas of the D peak and G peak of each particle, which were ID2 and IG2 respectively. The frequencies of ID2 / IG2 and ID1 / IG1 were counted with a step size of 0.02 to obtain a normal distribution graph. The average value of ID2 / IG2 was calculated to be the area ratio of the D peak to the G peak of the active material, ID2 / IG2. The average value of ID1 / IG1 was calculated to be the intensity ratio of the D peak to the G peak of the active material, ID1 / IG1. The laser wavelength of the Raman spectrometer can be in the range of 532nm to 785nm.

[0184] 3. True density

[0185] The GB / T 24586-2009 true density test standard is adopted, and the gas displacement method is used to test the true density of conductive carbon. The Archimedean principle (density = mass / volume) is applied. By detecting the pressure of the gas in the sample chamber and the expansion chamber, according to Bohr's law (PV = nRT), the true volume of the conductive carbon is measured to obtain its true density.

[0186] 4. Tap density

[0187] Weigh 50g of negative electrode material powder and place it entirely into a graduated cylinder. The cylinder, then mounted on the instrument, vibrates for a set number of times before stopping. After the vibrations are complete, read the volume based on the powder surface height and calculate the tap density. The test equipment used is a Dandong Better BT-301.

[0188] 5. Storage capacity retention rate:

[0189] Allow the lithium-ion battery to rest at 25°C for 5 minutes; charge to 3.65V at 0.33C, then charge to 0.05C at 3.65V; allow to rest for 5 minutes; discharge to 2V at 0.33C, recording the capacity at this point as Cz (the capacity of the cell at this step after storage is the reversible capacity, marked as Ct, where t is the storage time). Charge to 3.65V at 0.33C, then charge to 0.05C at 3.65V; at this point the cell is fully charged (SOC = 100%).

[0190] Step 2: Place the fully charged secondary battery in a 60°C environment and store it for a period of time t. Then take out the battery cell and test it according to the process of the first step. Then place the fully charged secondary battery in a 60°C environment and repeat the above operations to calculate the reversible capacity retention rate F2, F2 = Ct ÷ Cz * 100%.

[0191] The results are shown in Table 1 and Figure 3 shown.

[0192] Table 1 Distinguishing parameters and test results

[0193]

[0194]

[0195] According to Table 1, the conductive carbon provided in Examples 1-8 of the present application, compared with Comparative Examples 1 and 2, can effectively improve the battery's energy storage capacity retention rate after 15 days of full charge at 60°C and the energy storage capacity retention rate after 70 days of full charge at 60°C by adding conductive carbon with an ID1 / IG1 value of 0.2-1.01 and an ID2 / IG2 value of 0.3-1.99 to the negative electrode plate of the lithium iron phosphate battery, thereby effectively improving the battery storage life.

[0196] According to Examples 1, 2, and 6, under the condition that the ID1 / IG1 values ​​of the conductive carbon are the same, the ID2 / IG2 values ​​are not fixed and affect the storage life of the battery.

[0197] Figure 4 1 is a storage capacity retention rate change curve of the lithium-ion batteries in Examples 1, 4 and Comparative Example 1.

[0198] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A battery, characterized in that: The conductive carbon comprises conductive carbon, wherein the ID1 / IG1 value of the conductive carbon is 0.2-1.01, and the ID2 / IG2 value of the conductive carbon is 0.3-1.99; Among them, ID1 is the peak intensity of the D peak in the Raman spectrum of the conductive carbon, IG1 is the peak intensity of the G peak in the Raman spectrum of the conductive carbon, ID2 is the peak area of ​​the D peak in the Raman spectrum of the conductive carbon, and IG2 is the peak area of ​​the G peak in the Raman spectrum of the conductive carbon.

2. The battery according to claim 1, characterized in that The conductive carbon satisfies at least one of (a1) to (a5): (a1) The specific surface area of ​​the conductive carbon is 50m 2 / g-65m 2 / g; (a2) The true density of the conductive carbon is 1.90 g / cm 3 -1.98g / cm 3 ; (a3) The tap density of the conductive carbon is 0.09 g / cm 3 -0.15g / cm 3 ; (a4) the conductive carbon has an ID1 / IG1 value of 0.3-1.01 and an ID2 / IG2 value of 0.3-1.95; (a5) The conductive carbon includes at least one of Super P, acetylene black and Ketjen black.

3. The battery according to claim 1 or 2, characterized in that The battery comprises a positive electrode sheet and a negative electrode sheet, wherein the positive electrode sheet comprises a positive electrode active material, wherein the positive electrode active material comprises a transition metal phosphate with an olivine structure, and the negative electrode sheet comprises a negative electrode active material and conductive carbon; Optionally, the negative electrode active material includes graphite and / or silicon carbon.

4. The battery according to claim 3, characterized in that The olivine-structured transition metal phosphate includes Li α Fe β M 1-β PO4, 0<α≤1.1, 0≤β≤1, M includes one or more of Ti, Mg, Mn, V, Cr, Zr, Nb, and W.

5. The battery according to claim 3, characterized in that The olivine-structured transition metal phosphate includes LiFePO 4 , LiMnPO 4 and a solid solution thereof.

6. An electrical device, characterized in that: The battery comprises the battery according to any one of claims 1 to 5, wherein the battery is used to provide electrical energy to the electrical device.

7. A conductive carbon, characterized in that The specific surface area of ​​conductive carbon is 50m 2 / g-65m 2 / g, ID1 / IG1 value is 0.2-1.01, ID2 / IG2 value is 0.3-1.99; Among them, ID1 is the peak intensity of the D peak in the Raman spectrum of the conductive carbon, IG1 is the peak intensity of the G peak in the Raman spectrum of the conductive carbon, ID2 is the peak area of ​​the D peak in the Raman spectrum of the conductive carbon, and IG2 is the peak area of ​​the G peak in the Raman spectrum of the conductive carbon.

8. The conductive carbon according to claim 7, characterized in that The conductive carbon satisfies at least one of (b1) to (b3): (b1) The true density of the conductive carbon is 1.90 g / cm 3 -1.98g / cm 3 ; (b2) The tap density of the conductive carbon is 0.09 g / cm 3 -0.15g / cm 3 ; (b3) The ID1 / IG1 value of the conductive carbon is 0.3-1.01, and the ID2 / IG2 value is 0.3-1.

95.

9. The conductive carbon according to claim 7 or 8, characterized in that The conductive carbon comprises at least one of Super P, acetylene black and Ketjen black; Optionally, the conductive carbon is Super P.

10. The method for preparing conductive carbon according to any one of claims 7 to 9, characterized in that: include: In an inert atmosphere, the raw carbon is heat-treated at 1000° C.-3000° C. for at least 0.5 h to obtain the conductive carbon.

11. The preparation method according to claim 10, characterized in that: The specific surface area of ​​the raw carbon is 50m 2 / g-65m 2 / g, ID1 / IG1 value is 1.02-1.

45.

12. The preparation method according to claim 10 or 11, characterized in that: The heat treatment time is 0.5h-6h.

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