Conductive carbon and preparation method therefor, and battery and electric apparatus

Abstract

Conductive carbon and a preparation method therefor, and a battery and an electric apparatus, which relate to the field of batteries. The battery comprises conductive carbon, wherein an ID1 / IG1 value of the conductive carbon is 0.2 to 1.01, and an ID2 / IG2 value thereof is 0.3 to 1.99; and ID1 is the peak intensity of a D peak in a Raman spectrum of the conductive carbon, IG1 is the peak intensity of a 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. When the conductive carbon is applied, as a conductive agent, to a negative electrode sheet of an olivine-structured transition metal phosphate-based battery, the ID1 / IG1 and ID2 / IG2 of the conductive carbon are controlled within the ranges to effectively control the degree of a defect of the conductive carbon, thereby reducing the consumption of active lithium in the whole negative electrode sheet, improving the storage capacity retention rate of the battery, and prolonging the storage life.

Description

Conductive carbon, preparation method thereof, battery and electric device

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese Patent Application No. 202410445709.6, filed on April 12, 2024, entitled "Conductive carbon, preparation method thereof, battery and electric device", the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to the field of batteries, in particular, to a conductive carbon, a preparation method thereof, a battery and an electric device. BACKGROUND

[0004] In recent years, lithium ion batteries are widely used in energy storage power systems such as hydraulic, thermal, wind and solar power stations, and in many fields such as electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc., so higher requirements are put forward for the storage life of lithium ion batteries.

[0005] Taking a lithium ion battery whose positive active material includes an olivine-structured transition metal phosphate salt (referred to as an olivine-structured transition metal phosphate battery) as an example, it has good thermal stability and excellent charge-discharge cycle performance, but it has the problem of short storage life during use, which limits its further development.

[0006] SUMMARY

[0007] In view of the above problems, the present application provides a conductive carbon, a preparation method thereof, a battery and an electric device, which can improve the technical problem of short battery storage life.

[0008] In a first aspect, the embodiments of the present application provide a battery, which includes a conductive carbon, the ID1 / IG1 value of the conductive carbon is 0.2-1.01, and the ID2 / IG2 value is 0.3-1.99.

[0009] Wherein, 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.

[0010] The battery provided by the present application can effectively control the defect degree of the conductive carbon by applying the above-mentioned conductive carbon as a conductive agent to the negative electrode sheet of the olivine-structured transition metal phosphate battery, thereby reducing the active lithium consumption of the entire negative electrode sheet, improving the storage capacity retention rate of the battery, and prolonging the storage life.

[0011] In some embodiments, the conductive carbon satisfies at least one of (a1)-(a5):

[0012] (a1) the specific surface area of the conductive carbon is 50 m 2 / g-65 m 2 / g;

[0013] (a2) the true density of the conductive carbon is 1.90 g / cm 3 -1.98 g / cm 3 ;

[0014] (a3) the tap density of the conductive carbon is 0.09 g / cm 3 -0.15 g / cm 3 ;

[0015] (a4) the ID1 / IG1 value of the conductive carbon is 0.3-1.01, and the ID2 / IG2 value is 0.3-1.95;

[0016] (a5) the conductive carbon comprises at least one of Super P, acetylene black and Ketjen black.

[0017] By controlling the parameters and components of the conductive carbon to be selected within the above ranges, when the conductive carbon is applied as a conductive agent in the negative electrode sheet of the olivine-structured transition metal phosphate battery, not only can the active lithium consumption of the entire negative electrode sheet be reduced to improve the battery storage capacity retention rate, but also the other electrochemical performance of the battery can be further improved.

[0018] According to some embodiments of the present application, the battery comprises a positive electrode sheet and a negative electrode sheet, the positive electrode sheet comprises a positive electrode active material, the positive electrode active material comprises an olivine-structured transition metal phosphate salt, and the negative electrode sheet comprises a negative electrode active material and a conductive carbon. Since the main problem leading to the short storage life of the olivine-structured transition metal phosphate battery originates from the negative electrode side, by adding the conductive carbon to the negative electrode sheet of the olivine-structured transition metal phosphate battery, the active lithium consumption of the entire negative electrode sheet can be reduced, thereby effectively improving the storage life of the olivine-structured transition metal phosphate battery.

[0019] Optionally, the negative electrode active material comprises graphite and / or silicon-carbon.

[0020] In some embodiments, the olivine-structured transition metal phosphate salt comprises Li α Fe β M 1-βPO4, 0<α≤1.1, 0≤β≤1, M comprises one or more of Ti, Mg, Mn, V, Cr, Zr, Nb, W. When the above phosphotransition metal salt with olivine structure is used as the positive active material in the lithium ion battery, and the conductive carbon provided by the application is used as the conductive agent in the negative electrode sheet, the active lithium consumption of the whole negative electrode sheet can be reduced, thereby effectively improving the storage life of the battery.

[0021] In some embodiments, the phosphotransition metal salt with olivine structure is LiFePO4, LiMnPO4, and a solid solution of the two. LiFePO4 and LiMnPO4 or the solid solution formed by mixing them are safe and inexpensive, and can make the battery have high cycle performance and high stability when applied to the battery. Therefore, the battery using the above phosphotransition metal salt with olivine structure as the positive active material can have high cycle performance, high stability, and high storage life.

[0022] In a second aspect, the application provides a power utilization device comprising the battery in the above embodiments, and the battery is used to provide electric energy.

[0023] In a third aspect, the application further provides a conductive carbon, wherein the specific surface area of the conductive carbon is 50m 2 / g-65m 2 , the ID1 / IG1 value is 0.2-1.01, and the ID2 / IG2 value is 0.3-1.99.

[0024] 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.

[0025] In the technical scheme of the embodiments of the application, by controlling the specific surface area of the conductive carbon to be 50m 2 / g-65m 2 , and the ID1 / IG1 and ID2 / IG2 of the conductive carbon being within the above ranges, the defect degree of the conductive carbon can be effectively controlled. When the conductive carbon is applied to the negative electrode sheet of the phosphotransition metal salt battery with olivine structure as the conductive agent, the active lithium consumption of the whole negative electrode sheet can be reduced, thereby improving the storage capacity retention rate of the battery and prolonging the storage life.

[0026] In some embodiments, the conductive carbon satisfies at least one of (b1)-(b3):

[0027] (b1) the true density of the conductive carbon is 1.90g / cm 3 -1.98g / cm 3 .

[0028] (b2) The tap density of conductive carbon is 0.09 g / cm 3 -0.15g / cm 3 ;

[0029] (b3) The ID1 / IG1 value of conductive carbon is 0.3-1.01, and the ID2 / IG2 value is 0.3-1.95.

[0030] 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.

[0031] 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.

[0032] Optionally, the conductive carbon is Super P.

[0033] In a fourth aspect, the present application provides a method for preparing the conductive carbon in the above embodiment, comprising:

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] The above description is only a summary of the technical solutions of the present application. In order to make the technical means of the present application more clearly understood and implemented according to the content of the description, and in order to make the above and other purposes, characteristics and advantages of the present application more obvious and easy to understand, the following specific embodiments of the present application are described. BRIEF DESCRIPTION OF DRAWINGS

[0039] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a better understanding of the preferred embodiments, and are not to be considered as limiting of the present application. Moreover, in the drawings, like reference numerals denote same or similar components. In the drawings:

[0040] FIG. 1 is a structural schematic diagram of a vehicle according to some embodiments of the present application;

[0041] FIG. 2 is an exploded structural schematic diagram of a battery according to some embodiments of the present application;

[0042] FIG. 3 is an exploded structural schematic diagram of a battery cell according to some embodiments of the present application;

[0043] FIG. 4 is a storage capacity change curve diagram of lithium ion batteries in Examples 1-3 and Comparative Example 1.

[0044] Reference signs in the detailed description are as follows:

[0045] 1000 - vehicle;

[0046] 100 - battery; 200 - controller; 300 - motor;

[0047] 10 - case; 11 - first part; 12 - second part;

[0048] 20 - battery cell; 21 - housing; 22 - electrode assembly; 23 - electrode terminal; 24 - pressure relief structure;

[0049] 211 - housing; 212 - cover. DETAILED DESCRIPTION

[0050] The embodiments of the technical solutions of the present application will be described in detail below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application; the use of the terms "including," "comprising," or "having" and variations thereof herein is intended to be broad and encompass the terms "consisting of" and "consisting essentially of" and variations thereof. Unless otherwise required by context, singular terms shall include pluralities and vice versa. Unless otherwise required by context, the use herein of the singular is also to be construed as a reference to the plural and vice versa.

[0052] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise explicitly and specifically limited.

[0053] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearance of the phrase in various places in the specification is not necessarily all referring to the same embodiment, or to a particular embodiment, or to a particular set of embodiments. It will be explicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0054] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " herein generally represents an "or" relationship between the front and rear associated objects.

[0055] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two), and similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0056] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and therefore cannot be understood as limiting the embodiments of the present application, which do not indicate or imply that the indicated devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the embodiments of the present application.

[0057] In the description of the embodiments of the present application, unless otherwise explicitly specified and limited, the technical terms "mounting", "connection", "linking", "fixing" and the like should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integral; can be mechanical connection, can also be electrical connection; can be direct connection, can also be indirect connection through an intermediate medium, can be internal communication of two elements or interaction relationship between two elements. For those skilled in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0058] In recent years, lithium ion batteries are widely used, for example, batteries with positive active materials including olivine-structured transition metal phosphate salts (hereinafter referred to as olivine-structured transition metal phosphate salt batteries) have good thermal stability and excellent charge-discharge cycle performance, but have the problem of short storage life during use, which limits their further development.

[0059] Among them, the main problem leading to the short storage life of olivine-structured transition metal phosphate salt batteries comes from the negative electrode side, so the current improvement direction for the storage life of olivine-structured transition metal phosphate salt batteries mainly includes (1) modification of negative active materials, (2) artificial SEI, and (3) modification of electrolyte.

[0060] Considering that the negative electrode sheet includes not only negative active materials but also conductive carbon and adhesives, and the specific surface area of the conductive carbon is 20-60 times that of general negative active materials such as graphite (specific surface area ~ 1-3 m 2 / g), that is, compared with graphite, the conductive carbon has abundant pores, and the more abundant the pores of the carbon material, the more defects and oxygen-containing functional groups exist, which leads to the consumption of more active lithium during the storage of the battery, thereby affecting the storage life of the battery.

[0061] Therefore, based on the above considerations, in order to improve the problem of short storage life of the battery, the present application provides a battery including 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;

[0062] 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.

[0063] The battery provided in the application can effectively control the defect degree of the conductive carbon by controlling the ID1 / IG1 and ID2 / IG2 of the conductive carbon within the above range when the conductive carbon is applied to the negative electrode sheet of the olivine structure phosphoric acid transition metal salt battery as a conductive agent, thereby reducing the active lithium consumption of the entire negative electrode sheet, improving the storage capacity retention rate of the battery, and prolonging the storage life.

[0064] The battery disclosed in the embodiments of the application can be a power battery or an energy storage battery. The application scenarios of the power battery include, but are not limited to, vehicles, ships, aircraft, spacecraft, electric tools, electric toys, various mobile terminals, and the like. The application scenarios of the energy storage battery include, but are not limited to, solar power generation systems, hydroelectric power generation systems, wind power generation systems, and the like. All of them are beneficial to alleviate and improve the performance of the battery, and are beneficial to improve the storage life of the olivine structure phosphoric acid transition metal salt battery.

[0065] The embodiments of the application provide a power consumption device using a battery as a power supply. The power consumption device can be, but is not limited to, a mobile phone, a tablet computer, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric car, a ship, a spacecraft, and the like. The electric toy can include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, an electric plane toy, and the like. The spacecraft can include an airplane, a rocket, a space shuttle, a spacecraft, and the like.

[0066] The following embodiments are described by taking a power consumption device in an embodiment of the application as a vehicle 1000 for convenience of description.

[0067] Please refer to FIG. 1, which is a structural schematic diagram of a vehicle 1000 provided in some embodiments of the application. The vehicle 1000 can be a fuel automobile, a gas automobile, or a new energy automobile. The new energy automobile can be a pure electric automobile, a hybrid electric automobile, or a range extended automobile, etc. The vehicle 1000 is internally provided with a battery 100. The battery 100 can be arranged at the bottom, the head, or the tail of the vehicle 1000. The battery 100 can be used for power supply of the vehicle 1000, for example, the battery 100 can be used as an operating power supply of the vehicle 1000. The vehicle 1000 can further include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to supply power to the motor 300, for example, to meet the working power demand of the vehicle 1000 during starting, navigation, and driving.

[0068] In some embodiments of the application, the battery 100 can not only be used as an operating power supply of the vehicle 1000, but also be used as a driving power supply of the vehicle 1000, instead of or partially instead of fuel or natural gas to provide driving power for the vehicle 1000.

[0069] In the present application, the battery 100 refers to a single physical module including one or more battery monomers 20 to provide a certain voltage and capacity, which can be in the form of a battery pack, a battery module, etc. The battery 100 can also include a box 10 for packaging one or more battery monomers 20, which can avoid the influence of liquid or other foreign matters on the charging or discharging of the battery monomer 20.

[0070] Please refer to FIG. 2, which is an exploded view of the battery 100 provided by some embodiments of the present application. The battery 100 includes the box 10 and the battery monomer 20, and the battery monomer 20 is contained in the box 10. Among them, the box 10 is used to provide a containing space for the battery monomer 20, and the box 10 can adopt various structures. In some embodiments, the box 10 can include a first part 11 and a second part 12, and the first part 11 and the second part 12 are mutually covered. The first part 11 and the second part 12 jointly define a containing space for containing the battery monomer 20. The second part 12 can be a hollow structure with one end open, and the first part 11 can be a plate-shaped structure, which is covered on the open side of the second part 12 to make the first part 11 and the second part 12 jointly define the containing space. The first part 11 and the second part 12 can also be hollow structures with one side open, and the open side of the first part 11 is covered on the open side of the second part 12. Of course, the box 10 formed by the first part 11 and the second part 12 can have various shapes, such as a cylinder, a cuboid, etc.

[0071] In the battery 100, the battery monomer 20 can be multiple, and the multiple battery monomers 20 can be connected in series, in parallel, or in a mixed connection. The mixed connection means that there are both series and parallel connections among the multiple battery monomers 20. The multiple battery monomers 20 can be directly connected in series, in parallel, or in a mixed connection, and then the whole of the multiple battery monomers 20 is contained in the box 10. Of course, the battery 100 can also be that the multiple battery monomers 20 are first connected in series, in parallel, or in a mixed connection to form a battery module, and then the multiple battery modules are connected in series, in parallel, or in a mixed connection to form a whole, which is contained in the box 10. The battery 100 can also include other structures, for example, the battery 100 can also include a busbar component for realizing the electrical connection between the multiple battery monomers 20.

[0072] The battery monomer 20 refers to the smallest unit that constitutes the battery 100.

[0073] Please refer to FIG. 3, which is an exploded structural schematic view of the battery monomer 20 provided by some embodiments of the present application. As shown in FIG. 3, the battery monomer 20 can include a shell 21, an electrode assembly 22, and an electrolyte, and the electrode assembly 22 and the electrolyte are contained in the shell 21.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] The positive current collector can be a metal foil or a composite current collector. For example, the material of the positive current collector and the positive tab can be aluminum. The composite current collector can 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 can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer material base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0080] In some embodiments, the positive active material layer optionally further includes a binder. As an example, the binder can 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 acrylic ester resin.

[0081] In some embodiments, the positive active material layer optionally further includes a conductive agent. As an example, the conductive agent can include at least one of super conductive carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0082] The separator film is between the positive electrode tab and the negative electrode tab and serves to separate them. The type of the separator film is not particularly limited in the embodiments of the present application, and any known porous structure separator film having good chemical stability and mechanical stability can be used.

[0083] In some embodiments, the material of the separator film can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator film can be a single-layer film or a multi-layer composite film, and is not particularly limited. When the separator film is a multi-layer composite film, the materials of the layers can be the same or different, and are not particularly limited.

[0084] The negative electrode tab includes a negative current collector, a negative tab, and a negative active material layer. The negative active material layer is disposed on at least one side of the negative current collector, and includes a negative active material. A primer layer or the like can be further disposed between the negative current collector and the negative active material layer. The negative tab protrudes from the negative current collector, and is located at one end or opposite ends of the negative current collector, for example.

[0085] 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 can 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 can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer material base layer (such as a base layer of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0086] In some embodiments, the negative active material layer optionally further includes a conductive agent. As an example, the conductive agent can include at least one of acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, and carbon nanofibers.

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

[0088] In some embodiments, the negative active material layer optionally further includes other auxiliary agents, such as a thickening agent (e.g., sodium carboxymethyl cellulose (CMC-Na), etc.

[0089] According to some embodiments of the present application, the battery includes conductive carbon having an ID1 / IG1 value of 0.2-1.01 and an ID2 / IG2 value of 0.3-1.99.

[0090] 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.

[0091] Both the D peak and the G peak are Raman characteristic peaks of carbon atom crystals. The D peak is a scattering peak with a Raman shift of 1328-1359 cm -1 The G peak is a scattering peak with a Raman shift of 1578-1585 cm -1 ID1 / IG1 and ID2 / IG2 both represent the degree of defects of the conductive carbon. The greater the ratio of ID1 / IG1 and ID2 / IG2, the greater the degree of defects.

[0092] The battery provided in the application, when the above conductive carbon is applied as a conductive agent in the negative electrode sheet of the olivine structure phosphoric acid transition metal salt battery, the defect degree of the conductive carbon is effectively controlled by controlling ID1 / IG1 and ID2 / IG2 within the above range, thereby reducing the active lithium consumption of the entire negative electrode sheet, improving the battery storage capacity retention rate, and prolonging the storage life.

[0093] 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 cracking black.

[0094] According to some embodiments of the application, the conductive carbon satisfies at least one of (a1)-(a5):

[0095] (a1) The specific surface area of the conductive carbon is 50 m 2 / g-65 m 2 / g.

[0096] Since the conductive carbon has a porous structure, it can have a certain adsorption effect on the electrolyte, and 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, further controlling the specific surface area of the conductive carbon within the above range can further control the pore structure of the conductive carbon by controlling the specific surface area of the conductive carbon within the above range, so that when the conductive carbon is applied as a conductive agent in the negative electrode sheet of the olivine structure phosphoric acid transition metal salt battery, not only the battery storage life can be improved, but also the wettability of the electrolyte can be improved, indirectly improving the transmission rate of lithium ions and improving the electrochemical performance of the battery.

[0097] Exemplarily, the specific surface area of the conductive carbon is any value or between any two values in 50 m 2 / g, 55 m 2 / g, 60 m 2 / g, 65 m 2 / g.

[0098] Alternatively, the specific surface area of the conductive carbon is 53 m 2 / g-65 m 2 / g.

[0099] Exemplarily, the specific surface area of the conductive carbon is any value or between any two values in 53 m 2 / g, 55 m 2 / g, 57 m 2 / g, 60 m 2 / g, 63 m 2 / g, 65 m 2 / g.

[0100] (a2) the true density of the conductive carbon is 1.90 g / cm 3 -1.98 g / cm 3 ;

[0101] 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, controlling the true density thereof within the above range makes the conductive carbon have better electrical conductivity and specific surface area while improving surface defects, which is beneficial to improving the electrochemical performance of the battery.

[0102] Illustratively, the true density of the conductive carbon is any value in 1.900 g / cm 3 , 1.910 g / cm 3 , 1.920 g / cm 3 , 1.925 g / g / cm 3 , 1.930 g / cm 3 , 1.935 g / cm 3 , 1.940 g / cm 3 , 1.945 g / cm 3 , 1.950 g / g / cm 3 , 1.960 g / cm 3 , 1.970 g / cm 3 , 1.980 g / cm 3 or between any two values.

[0103] (a3) the tap density of the conductive carbon is 0.09 g / cm 3 -0.15 g / cm 3 ;

[0104] Controlling the tap density within the above range, the conductive carbon particles have a certain porosity, so that when it is applied to the battery as a conductive agent, it can promote the movement of ions in the electrolyte between the electrodes, thereby improving the electrochemical performance of the battery.

[0105] Illustratively, the tap density of the conductive carbon is any value in 0.09 g / cm 3 , 0.10 g / cm 3 , 0.11 g / cm 3 , 0.12 g / g / cm 3 , 0.15 g / cm 3 or between any two values.

[0106] (a4) the ID1 / IG1 value of the conductive carbon is 0.3-1.01 and the ID2 / IG2 value is 0.3-1.95;

[0107] The ID1 / IG1 value and the ID2 / IG2 value of the conductive carbon are controlled within the above range, which is beneficial to control the defect degree of the surface of the conductive carbon, so that when the conductive carbon is applied to the negative electrode sheet of the olivine-structured transition metal phosphate battery as a conductive agent, the active lithium consumption of the whole negative electrode sheet can be reduced, thereby improving the storage capacity retention rate of the battery and prolonging the storage life.

[0108] (a5) The conductive carbon includes at least one of Super P, acetylene black and ketjen black.

[0109] The conductive carbon has good conductivity and a wide range of applications, can directly participate in constructing a short-range and long-range conductive network in a lithium ion battery, and significantly improves the electrical performance of the battery. In addition, the conductive carbon also has a high specific surface area, which can improve the wettability of the electrolyte and indirectly improve the transmission rate of lithium ions, thereby improving the electrical performance of the battery.

[0110] Optionally, the conductive carbon is Super P.

[0111] The Super P has good conductivity, is easy to obtain and has high cost performance, and can reduce the preparation cost.

[0112] 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 salt, and the negative electrode sheet includes a negative electrode active material and a conductive carbon.

[0113] Since the main problem causing the short storage life of the olivine-structured transition metal phosphate battery is from the negative electrode side, by adding the conductive carbon to the negative electrode sheet of the olivine-structured transition metal phosphate battery, the active lithium consumption of the whole negative electrode sheet can be reduced, thereby effectively improving the storage life of the olivine-structured transition metal phosphate battery.

[0114] Optionally, the negative electrode active material includes graphite and / or silicon-carbon.

[0115] The negative electrode active material has high safety and is easy to industrialize, and has a much smaller specific surface area than the conductive carbon, which can alleviate the consumption of active lithium during storage.

[0116] According to some embodiments of the present application, the olivine-structured transition metal phosphate salt includes Li α Fe β M 1-β PO4, 0 < a ≤ 1.1, 0 ≤ β ≤ 1, and M includes one or more of Ti, Mg, Mn, V, Cr, Zr, Nb and W.

[0117] When the above phosphotransition metal salt with olivine structure is used as the positive active material in the lithium ion battery, and the conductive carbon provided by the application is used as the conductive agent in the negative electrode sheet, the consumption of active lithium in the whole negative electrode sheet is reduced, thereby effectively improving the storage life of the battery.

[0118] It should be noted that the above phosphotransition metal salt with olivine structure includes but is not limited to the components shown in the above examples.

[0119] It should be noted that the battery will be accompanied by Li deintercalation and consumption during charging and discharging, and the molar content of Li is different when the battery is discharged to different states. In the application, the molar content of Li in the list of phosphotransition metal salt with olivine structure is the initial state of the material, i.e. the state before feeding. After the phosphotransition metal salt with olivine structure is applied to the battery system and undergoes charging and discharging cycles, the molar content of Li will change. In the application, the molar content of O in the list of phosphotransition metal salt with olivine structure is only the theoretical state value. The release of oxygen from the crystal lattice will cause the molar content of oxygen to change, and the actual molar content of O will fluctuate.

[0120] According to some embodiments of the application, the phosphotransition metal salt with olivine structure is LiFePO4, LiMnPO4, and a solid solution of the two.

[0121] The solid solution of LiFePO4 and LiMnPO4 refers to LiFe α M 1-α PO4 (lithium manganese iron phosphate, LMFP).

[0122] The solid solution of LiFePO4 and LiMnPO4 or their mixture is safe and inexpensive, and can make the battery have high cycle and high stability after being applied to the battery. Therefore, the battery using the above phosphotransition metal salt with olivine structure as the positive active material can have high cycle, high stability and high storage life.

[0123] According to some embodiments of the application, the application further provides a power consumption device, which comprises the battery of any of the above schemes, and the battery is used to provide electric energy for the power consumption device.

[0124] The power consumption device can be the device or system of any of the above applications.

[0125] According to some embodiments of the application, the application further provides a conductive carbon, wherein the specific surface area of the conductive carbon is 50m 2 / g-65m 2 / g, the ID1 / IG1 value is 0.2-1.01, and the ID2 / IG2 value is 0.3-1.99.

[0126] ID1 / IG1 and ID2 / IG2 are both indicative of the defect degree of the conductive carbon, the greater the ratio of ID1 / IG1, ID2 / IG2, the greater the defect degree.

[0127] Both D peak and G peak are Raman characteristic peaks of carbon atom crystal, D peak is a scattering peak with Raman shift of 1328-1359 cm -1 -1 G peak is a scattering peak with Raman shift of 1578-1585 cm 2 ID1 / IG1 and ID2 / IG2 are both indicative of the defect degree of the conductive carbon, the greater the ratio of ID1 / IG1, ID2 / IG2, the greater the defect degree.

[0128] The specific surface area is the meaning known in the art, which can be measured by instruments and methods known in the art, for example, can be tested by nitrogen adsorption specific surface area analysis test method, and calculated by BET method.

[0129] The conductive carbon provided in the present application controls the ID1 / IG1 and ID2 / IG2 of the conductive carbon with specific surface area of 50 m 2 / g-65 m 2 / g within the above range, effectively controls the defect degree of the conductive carbon, so that it can be directly applied to the negative electrode sheet of the olivine structure phosphoric acid transition metal salt battery as a conductive agent, can reduce the active lithium consumption of the whole negative electrode sheet, thereby improving the battery storage capacity retention rate and prolonging the storage life.

[0130] Illustratively, the specific surface area of the conductive carbon is any value or between any two values in 50 m 2 / g, 53 m 2 / g, 55 m 2 / g, 58 m 2 / g, 60 m 2 / g, 63 m 2 / g, 65 m 2 / g. 2 / g.

[0131] Illustratively, the ID1 / IG1 value of the conductive carbon is any value or between any two values in 0.2, 0.3, 0.5, 0.7, 1.0, 1.01.

[0132] Illustratively, the ID2 / IG2 value of the conductive carbon is any value or between any two values in 0.3, 0.5, 0.7, 1.0, 1.2, 1.5, 1.98, 1.99.

[0133] ​In some optional embodiments, the conductive carbon satisfies at least one of (b1)-(b3):

[0134] (b1) the true density of the conductive carbon is 1.90 g / cm 3 -1.98 g / cm 3 ;

[0135] 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, controlling the true density thereof within the above range makes the conductive carbon have better conductivity and specific surface area while improving surface defects, which is beneficial to improving the electrochemical performance of the battery.

[0136] Illustratively, the true density of the conductive carbon is any value in 1.900 g / cm 3 , 1.920 g / cm 3 , 1.925 g / g / cm 3 , 1.930 g / cm 3 , 1.935 g / cm 3 , 1.940 g / cm 3 , 1.945 g / cm 3 , 1.950 g / g / cm 3 , 1.980 g / cm 3 , or between any two values.

[0137] (b2) the tap density of the conductive carbon is 0.09 g / cm 3 -0.15 g / cm 3 ;

[0138] Controlling the tap density within the above range makes the conductive carbon have a certain porosity between particles, so that when it is applied to the battery as a conductive agent, it can promote the movement of ions in the electrolyte between electrodes, thereby improving the electrochemical performance of the battery.

[0139] Illustratively, the tap density of the conductive carbon is any value in 0.09 g / cm 3 , 0.10 g / cm 3 , 0.11 g / cm 3 , 0.12 g / g / cm 3 , 0.15 g / cm 3 , or between any two values.

[0140] (b3) the ID1 / IG1 value of the conductive carbon is 0.3-1.01, and the ID2 / IG2 value is 0.3-1.95.

[0141] The ID1 / IG1 value and the ID2 / IG2 value of the conductive carbon are controlled within the above range, which is beneficial to control the defect degree of the surface of the conductive carbon, so that when the conductive carbon is applied to the negative electrode sheet of the olivine structure phosphoric acid transition metal salt battery as a conductive agent, the active lithium consumption of the whole negative electrode sheet can be reduced, thereby improving the storage capacity retention rate of the battery and prolonging the storage life.

[0142] 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 cracking black.

[0143] In some optional embodiments, the conductive carbon includes at least one of Super P, acetylene black and ketjen black.

[0144] The conductive carbon has good conductivity and wide application range, can directly participate in constructing a short-range and long-range conductive network in a lithium ion battery, and significantly improves the electrical performance of the battery; and the conductive carbon also has a high specific surface area, can improve the infiltration of electrolyte, indirectly improves the transmission rate of lithium ions, and improves the electrical performance of the battery.

[0145] Optionally, the conductive carbon is Super P.

[0146] Super P has good conductivity, is easy to obtain and has high cost performance, and can reduce the preparation cost.

[0147] According to some embodiments of the present application, the present application also provides a preparation method of the above conductive carbon, which includes:

[0148] The raw carbon is heat-treated at 1000-3000℃ for at least 0.5h in an inert atmosphere to obtain the conductive carbon.

[0149] The raw carbon refers to carbon material that is not treated according to the present application, that is, the raw carbon is carbon material before the above heat treatment. The raw carbon includes but is not limited to Super P, acetylene black, ketjen black, carbon nanofiber, etc. It can be understood that the type of the raw carbon is the same as that of the final conductive carbon, and the heat treatment does not change the type, 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 directly purchased on the market, or can be prepared by itself. For example, the preparation steps of the raw carbon include but are not limited to: after the raw material containing a carbon source (such as petroleum pitch, natural rubber, coal, polymer, etc.) is subjected to odor removal, dehydration, filtration, drying and other pretreatment processes, it is placed in an electric furnace or a kiln, heated to 500-900℃ for heat preservation pyrolysis, and the carbon black obtained after the pyrolysis is completed is used as the raw carbon.

[0150] 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, it can be understood that the degree of surface defects can be effectively reduced by the above high-temperature heat treatment, that is, the ID1 / IG1 value and the ID2 / IG2 value of the conductive carbon are both greater than the ID1 / IG1 value and the ID2 / IG2 value of the raw material carbon before the conductive carbon is high-temperature heat-treated.

[0151] The inert atmosphere includes nitrogen and / or argon.

[0152] The raw material carbon is heat-treated at 1000-3000℃ for at least 0.5h in an inert atmosphere, which is beneficial to control the defect degree of the conductive carbon within a reasonable range, so that when the conductive carbon is applied as a conductive agent in the negative electrode sheet of the olivine structure phosphoric acid transition metal salt battery, the active lithium consumption of the entire negative electrode sheet can be reduced, thereby improving the battery storage life. Exemplarily, the heat treatment temperature is any value or between any two values in 1000℃, 1150℃, 1300℃, 1500℃, 1700℃, 2000℃, 2300℃, 2500℃, 2800℃, 3000℃.

[0153] In summary, the preparation method provided in the present application is simple and controllable, and the defect degree of the conductive carbon can be effectively controlled by the above method, so that when the conductive carbon is applied as a conductive agent in the negative electrode sheet of the olivine structure phosphoric acid transition metal salt battery, the active lithium consumption of the entire negative electrode sheet can be reduced, thereby improving the battery storage life.

[0154] 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 material carbon, thereby reducing the active lithium consumption of the entire negative electrode when the raw material carbon is applied in the olivine structure phosphoric acid transition metal salt battery, so that the true density of the conductive carbon is lower than that of the corresponding raw material carbon, and the tap density of the conductive carbon is higher than that of the corresponding raw material carbon.

[0155] It should be noted that the preparation method of the conductive carbon includes but is not limited to the above heat treatment method, and can also be a laser radiation heat treatment method.

[0156] According to some embodiments of the present application, the specific surface area of the raw material carbon is 50m 2 / g-65m 2 / g, and the ID1 / IG1 value is 1.02-1.45.

[0157] The specific surface area of the raw material carbon is in the above range, which is beneficial to control the specific surface area of the conductive carbon by heat treatment to meet the relevant requirements, and can slow down the significant change of the infiltration performance due to the significant change of the specific surface area, which affects the electrochemical performance of the battery. At the same time, the ID1 / IG1 value of the raw material carbon in the above range is also beneficial to control the defects of the conductive carbon by heat treatment to meet the relevant requirements.

[0158] In some optional embodiments, the heat treatment time is 0.5h-6h.

[0159] Controlling the heat treatment temperature and / or time in the above range is beneficial to control the defects of the conductive carbon and the required energy consumption within a reasonable range, so that when it is applied as a conductive agent in the negative electrode sheet of the olivine structure phosphoric acid transition metal salt battery, it is beneficial to reduce the active lithium consumption of the entire negative electrode sheet and improve the battery storage life.

[0160] The heat treatment time is too short to effectively improve the defects of the raw material carbon, and the heat treatment time is too long to increase the production cost, therefore, controlling the heat treatment time to be 0.5h-6h is beneficial to control the defects of the conductive carbon and the required energy consumption within a reasonable range. Exemplarily, the heat treatment time is any one value or between any two values in 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h.

[0161] Some specific embodiments are listed below to better illustrate the present application.

[0162] Embodiment 1

[0163]

Raw material carbon

[0164] Super P, the specific surface area of which is 61.4m 2 / g, the ID1 / IG1 value is 1.02, the ID2 / IG2 value is 2.01, the true density is 1.978g / cm 3 , and the tap density is 0.07g / cm 3 .

[0165]

Conductive carbon

[0166] The raw material carbon is heat-treated at 1150℃ for 4h in a nitrogen atmosphere, and then naturally cooled to obtain the conductive carbon.

[0167]

Positive electrode sheet

[0168] Lithium iron phosphate, conductive agent carbon black (Super P, raw material carbon described above), binder PVDF were mixed in a weight ratio of 97.2:0.7:2.1 in an appropriate amount of N-methyl pyrrolidone (NMP) and stirred sufficiently to form a uniform positive electrode slurry. The positive electrode slurry was coated on the surface of a positive electrode current collector aluminum foil, and after drying, cold pressing, slitting, and cutting, a positive electrode tab was obtained. The tap density of the positive electrode tab was 2.45 g / cm 3 , and the area density was 21.68 mg / cm 2 .

[0169]

Negative electrode tab

[0170] The negative electrode active material artificial graphite, the conductive carbon described above, the thickening agent sodium carboxymethyl cellulose (CMC), and the binder were mixed in a mass ratio of 96.82:0.53:0.7:1.95, deionized water was added, and the system was stirred to be uniform under the action of a vacuum stirrer. The system was uniformly coated on both surfaces of a negative electrode current collector copper foil with a thickness of 6 μm, dried at 110°C for 20 min, and after drying, the tab was cold pressed to obtain a negative electrode tab with a coating weight of 10.71 mg / cm2, a tap density of 1.4 g / cm 3 , and a tab thickness of 159 μm.

[0171]

Separator

[0172] A polyethylene film with a thickness of 12 μm was selected as the separator.

[0173]

Electrolyte

[0174] Vinyl carbonate (EC), methyl ethyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain an organic solvent, and the lithium salt LiPF6 was dissolved in the organic solvent to obtain an electrolyte. The concentration of the lithium salt was 1 mol / L.

[0175]

Lithium ion battery

[0176] The positive electrode tab, the separator, and the negative electrode tab prepared above were stacked in order, with the separator between the positive and negative electrodes to play a separating role, and were wound to obtain an electrode assembly. The electrode assembly was placed in an outer package, electrolyte was injected, and the package was sealed. After formation, degassing, and edge cutting processes, a lithium ion battery was obtained.

[0177] Examples 2-8 and Comparative Examples 1-2

[0178] The only difference between the examples and comparative examples and Example 1 is shown in Table 1.

[0179] In Comparative Example 1, the untreated raw material carbon was directly used as the conductive carbon.

[0180] Comparative Example 2 differs from Example 1 only in that the raw carbon was heat treated at 500°C for 1 h.

[0181] Test Example

[0182] The conductive carbon and batteries in each example and Comparative Example 1 were tested, and the testing methods were as follows:

[0183] 1. Specific surface area testing method:

[0184] The specific surface area was tested using the national standard GB / T 19587-2004, “Determination of the specific surface area of solid materials by gas adsorption, BET method”.

[0185] 2. ID2 / IG2 and ID1 / IG1 testing method:

[0186] The conductive carbon was placed on a glass slide, and an area of 140 pm x 140 pm was selected on the surface of the conductive carbon layer. A laser confocal Raman microscope (Raman, HR Evolution, HORIBA Scientific) was used to scan the particles in the area, and the D peak and G peak of all the particles in the area were obtained, wherein: the D peak appeared at 1328-1359 cm -1 ; the G peak appeared at 1578-1585 cm -1 ; the LabSpec software was used to process the data to obtain the peak intensity of the D peak and G peak of each particle, which were ID1 and IG1, respectively. The LabSpec software was used to process the data to obtain the peak area of the D peak and G peak of each particle, which were ID2 and IG2, respectively. The frequency of ID2 / IG2 and ID1 / IG1 was counted with a step size of 0.02 to obtain a normal distribution graph. The mean value of ID2 / IG2 was calculated, which was the D peak to G peak area ratio ID2 / IG2 of the active material. The mean value of ID1 / IG1 was calculated, which was the D peak to G peak intensity ratio ID1 / IG1 of the active material. The laser wavelength of the Raman spectrometer could be in the range of 532 nm to 785 nm.

[0187] 3. True density

[0188] The true density of the conductive carbon was tested using the gas displacement method according to the GB / T 24586-2009 true density testing standard. The Archimedes principle (density = mass / volume) was applied, and the pressures of the gas in the sample chamber and the expansion chamber were detected. According to Boyle's law (PV = nRT), the true volume of the conductive carbon was measured, and thus the true density was obtained.

[0189] 4. Tapped density

[0190] Weigh 50 g of negative electrode material powder, all into the measuring cylinder, then fix the measuring cylinder containing the powder to the instrument and vibrate, reach the set number of times, stop vibrating. After the vibration, read the volume according to the height of the powder surface, then calculate the tap density. The test equipment is Dandong Bit BT-301.

[0191] 5. Storage capacity retention rate:

[0192] The lithium ion battery is placed at 25℃ for 5 minutes; charged to 3.65V at 0.33C0, 3.65V constant voltage charging to 0.05C0; stand for 5 minutes; discharge to 2V at 0.33C, record the capacity at this time as Cz (the capacity of the battery after storage at this step is the reversible capacity, marked as Ct, t is the storage time). Charged to 3.65V at 0.33C0, 3.65V constant voltage charging to 0.05C0, at this time the battery is full charged (SOC = 100%).

[0193] Second step: put the full charged secondary battery into 60℃ environment, after a period of time t, take out the battery and test according to the first step, then put the full charged secondary battery into 60℃ environment, repeat the above operation, calculate the reversible capacity retention rate F2, F2 = Ct ÷ Cz * 100%.

[0194] The results are shown in Table 1 and Figure 3.

[0195] Table 1: Different parameters and test results

[0196]

[0197] According to Table 1, the conductive carbon provided by Examples 1-8 can effectively improve the 60℃ full charge 15 day energy storage capacity retention rate and the 60℃ full charge 70 day energy storage capacity retention rate of the battery, and effectively improve the storage life of the battery, by adding the conductive carbon with ID1 / IG1 value of 0.2-1.01 and ID2 / IG2 value of 0.3-1.99 to the negative electrode sheet of the lithium iron phosphate battery.

[0198] According to Examples 1, 2 and 6, under the condition that the ID1 / IG1 value of the conductive carbon is the same, the ID2 / IG2 value is not fixed and affects the storage life of the battery.

[0199] Figure 4 is a storage capacity retention rate change curve diagram of the lithium ion battery in Examples 1, 4 and Comparative Example 1.

[0200] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than limit them. Although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some or all of the technical features can be replaced equivalently. Such modifications or replacements do not change the essence of the corresponding technical solutions, which should be covered in the scope of the present application. In particular, the technical features mentioned in each embodiment can be combined in any manner as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery, wherein: 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, wherein 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, wherein 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, wherein 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, wherein The olivine-structured transition metal phosphate includes LiFePO 4 , LiMnPO 4 and a solid solution thereof.

6. An electrical device, wherein: 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, wherein: 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, wherein 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, wherein 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, wherein: 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, wherein 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, wherein The heat treatment time is 0.5h-6h.

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