Hard carbon negative electrode material, preparation method and application thereof

Abstract

The application relates to the technical field of batteries, in particular to a hard carbon negative electrode material and a preparation method and application thereof. A preparation method of a negative electrode hard carbon material comprises the following steps: carrying out first heat treatment on a mixture of an organic metal catalyst and biomass activated carbon, introducing a gas-phase carbon source and carrying out second heat treatment to obtain first material, and carrying out carbonization treatment and acid pickling treatment on the first material. The method can improve the capacity and initial efficiency of the hard carbon negative electrode material through cooperation of various steps; the method is simple in process and easy to realize large-scale production.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more specifically, to a hard carbon anode material, its preparation method, and its application. Background Technology

[0002] Sodium resources are abundant and widely distributed, which can support the large-scale sustainable development of the industrial chain and ensure energy security. At the same time, sodium-ion batteries have good safety and low-temperature performance, making them an important supplement to lithium-ion batteries.

[0003] Sodium ions have a larger ionic radius than lithium ions. Traditional graphite anode materials have too small an interlayer spacing, making it difficult to accommodate sodium ion insertion and extraction. Therefore, developing carbon materials with larger interlayer spacing and porosity as anode materials is imperative. Hard carbon materials typically have an interlayer spacing of 0.37–0.40 nm, much larger than graphite itself. Their structure exhibits a long-range disordered arrangement, with abundant nanopores formed between micro-regions of different orientations. Therefore, they possess stronger storage capacity and higher sodium storage capacity. Current sodium-ion batteries have an energy density of 80–150 Wh / kg, lower than traditional lithium iron phosphate batteries (150–180 Wh / kg). Current hard carbon anode materials suffer from low reversible specific capacity (below 300 mAh / g) and poor coulombic efficiency, which limits their application in sodium-ion batteries.

[0004] Therefore, developing mass-producible high-capacity hard carbon anode materials has become an urgent problem to be solved in this field.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] One objective of this invention is to provide a method for preparing a hard carbon anode material to solve the technical problems of low reversible capacity and poor coulombic efficiency of existing hard carbon anode materials.

[0007] Another object of the present invention is to provide the aforementioned hard carbon anode material, which has excellent discharge specific capacity and first-efficiency.

[0008] Another object of the present invention is to provide a negative electrode.

[0009] Another object of the present invention is to provide a battery.

[0010] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0011] A method for preparing a negative electrode hard carbon material includes the following steps:

[0012] A mixture of organometallic catalyst and biomass activated carbon is subjected to a first heat treatment, followed by the introduction of a gaseous carbon source and a second heat treatment to obtain a first material. The first material is then subjected to carbonization and acid washing.

[0013] In one embodiment, the biomass activated carbon includes at least one of bamboo charcoal activated carbon, wood charcoal activated carbon, coconut shell activated carbon, and walnut shell activated carbon.

[0014] In one embodiment, the specific surface area of ​​the biomass activated carbon is 1550–2000 m². 2 / g, with a particle size of 5–10 μm.

[0015] In one embodiment, the organometallic catalyst comprises nickel dicenocene.

[0016] In one embodiment, the mass of the organometallic catalyst is 1% to 20% of the mass of the biomass activated carbon.

[0017] In one embodiment, the gaseous carbon source includes at least one selected from methane, ethane, propane, acetylene, ethylene, propylene, and toluene.

[0018] In one embodiment, the gaseous carbon source deposits carbon material in the pores of the biomass activated carbon by gas phase deposition, wherein the mass of the carbon material is 5% to 60% of the mass of the biomass activated carbon.

[0019] In one embodiment, the temperature of the first heat treatment is 140–180°C, and the time of the first heat treatment is 1–3 hours.

[0020] In one embodiment, the first heat treatment is performed under protective gas conditions.

[0021] In one embodiment, the temperature of the second heat treatment is 600–1000°C, and the time of the second heat treatment is 0.5–6 hours.

[0022] In one embodiment, the second heat treatment is performed under protective gas conditions.

[0023] In one embodiment, the heating rate of the second heat treatment is 0.5 to 10 °C / min.

[0024] In one embodiment, the carbonization treatment temperature is 1250–1550°C, and the carbonization treatment time is 2–8 hours.

[0025] In one embodiment, the carbonization process is carried out under protective gas conditions.

[0026] In one embodiment, the heating rate of the carbonization treatment is 0.5 to 10 °C / min.

[0027] In one embodiment, the acid used in the pickling treatment includes at least one of HCl, H2SO4, HNO3, H3PO4, and HClO4.

[0028] In one embodiment, the pickling process takes 2 to 24 hours.

[0029] A hard carbon anode material is prepared by the method described above; the hard carbon anode material has a discharge specific capacity of over 400 mAh / g at a current density of 30 mA / g and an initial efficiency of over 90%.

[0030] A negative electrode sheet comprising a hard carbon negative electrode material prepared by the aforementioned method, or the aforementioned hard carbon negative electrode material.

[0031] A battery comprising the aforementioned negative electrode.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] (1) The catalyst of the present invention can lead to the formation of onion carbon (onion carbon is formed around Ni particles), thereby introducing graphite domains. After acid washing, a large number of self-generated closed nanopores are formed, which can achieve the goal of high first efficiency and charging capacity. The deposition of gaseous carbon source leads to the formation of closed nanopores in biomass activated carbon, while the specific surface area of ​​the prepared hard carbon anode material is small. The method of the present invention, through the coordination of each step, is beneficial to improving the electrochemical performance of hard carbon anode material. The method is simple and easy to scale up.

[0034] (2) The hard carbon anode material obtained by the method of the present invention has a discharge specific capacity of more than 400 mAh / g at a current density of 30 mA / g and an initial efficiency of more than 90%.

[0035] (3) The battery prepared by the hard carbon anode material of the present invention has excellent cycle performance and rate performance. Attached Figure Description

[0036] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0037] Figure 1 This is a graph showing the electrochemical performance of the hard carbon anode material in Example 2 of the present invention. Detailed Implementation

[0038] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0039] According to one aspect of the present invention, the present invention relates to a method for preparing a negative electrode material, comprising the following steps:

[0040] A mixture of organometallic catalyst and biomass activated carbon is subjected to a first heat treatment, followed by the introduction of a gaseous carbon source and a second heat treatment to obtain a first material. The first material is then subjected to carbonization and acid washing.

[0041] The catalyst of this invention can lead to the formation of onion carbon (onion carbon forms around Ni particles), thereby introducing graphite domains. After acid washing, a large number of self-generated closed nanopores are formed, which can achieve the goal of high initial efficiency and charging capacity. Vapor deposition leads to the formation of closed nanopores in biomass activated carbon, while the specific surface area of ​​the prepared hard carbon anode material is small. The method of this invention, through the coordination of each step, is beneficial to improving the electrochemical performance of hard carbon anode materials. The method is simple and easy to scale up.

[0042] In one embodiment, the biomass activated carbon includes at least one of bamboo charcoal activated carbon, wood charcoal activated carbon, coconut shell activated carbon, and walnut shell activated carbon. The biomass activated carbon of the present invention can be selected from one or a combination of at least two of the above, such as a combination of bamboo charcoal activated carbon and wood charcoal activated carbon, a combination of coconut shell activated carbon and walnut shell activated carbon, or a combination of wood charcoal activated carbon, coconut shell activated carbon, and walnut shell activated carbon, etc.

[0043] In one embodiment, the specific surface area of ​​the biomass activated carbon is 1550–2000 m². 2 / g, including but not limited to 1550m 2 / g, 1600m 2 / g、1700m 2 / g、1800m 2 / g、1850m 2 / g、1900m 2 / g、2000m 2 / g, etc. Particle size is 5-10μm, for example 5μm, 5.5μm, 6μm, 7μm, 8μm, 9μm, 10μm, etc.

[0044] In one embodiment, the organometallic catalyst comprises nickel dicerocene. The mass of the organometallic catalyst is 1% to 20% of the mass of the biomass activated carbon, including but not limited to 1%, 2%, 3%, 4%, 5%, 6%, 7%, 10%, 12%, 13%, 15%, 18%, or 20%.

[0045] In one embodiment, the gaseous carbon source includes at least one selected from methane, ethane, propane, acetylene, ethylene, propylene, and toluene. In another embodiment, the gaseous carbon source is selected from any one of the above, or a combination of at least two, such as a combination of methane and ethane, propane and acetylene, ethylene, propylene, and toluene.

[0046] In one embodiment, the gaseous carbon source deposits carbon material in the pores of the biomass activated carbon by gas phase deposition, wherein the mass of the carbon material is 5% to 60% of the mass of the biomass activated carbon, for example, 5%, 10%, 15%, 20%, 30%, 40%, 50%, or 60%.

[0047] In one embodiment, the flow rate of the gaseous carbon source is 0.4 to 1 L / min, for example, 0.4 L / min, 0.5 L / min, 0.6 L / min, 0.7 L / min, 0.8 L / min or 1 L / min.

[0048] In one embodiment, the temperature of the first heat treatment is 140–180°C, including but not limited to 140°C, 145°C, 150°C, 155°C, 160°C, 170°C, and 180°C. The duration of the first heat treatment is 1–3 hours, including but not limited to 1 hour, 1.5 hours, 2 hours, 2.5 hours, or 3 hours. In one embodiment, the first heat treatment is performed under protective gas conditions. The suitable first heat treatment conditions employed in this invention are beneficial for subsequent gaseous carbon source deposition and coating.

[0049] In one embodiment, the temperature of the second heat treatment is 600–1000°C, including but not limited to 600°C, 650°C, 700°C, 750°C, 800°C, 900°C, and 1000°C; the time of the second heat treatment is 0.5–6 hours, including but not limited to 0.5 hours, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, or 6 hours. In one embodiment, the second heat treatment is performed under a protective gas atmosphere; the heating rate of the second heat treatment is 0.5–10°C / min, including but not limited to 0.5°C / min, 1°C / min, 2°C / min, 3°C / min, 5°C / min, 6°C / min, 8°C / min, or 10°C / min. The second heat treatment of the present invention uses appropriate temperature and time to enable the biomass activated carbon to form closed nanopores, ensuring the capacity and coulombic efficiency of the hard carbon anode material.

[0050] In one embodiment, the carbonization temperature is 1250–1550°C, including but not limited to 1250°C, 1280°C, 1300°C, 1320°C, 1350°C, 1380°C, 1400°C, 1420°C, 1450°C, 1480°C, 1500°C, 1520°C, and 1550°C. The carbonization time is 2–8 hours, including but not limited to 2 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, 65 hours, 7 hours, 7.5 hours, and 8 hours. In one embodiment, the carbonization is carried out under a protective gas atmosphere. The heating rate of the carbonization is 0.5–10°C / min, including 0.5°C / min, 1°C / min, 2°C / min, 3°C / min, 5°C / min, 6°C / min, 8°C / min, or 10°C / min. The present invention employs appropriate carbonization temperature and time, which is more conducive to improving the capacity and first coulombic efficiency of hard carbon anode materials.

[0051] In one embodiment, the protective gas involved in this invention includes at least one of N2, Ar, He, CO2, NH3, and H2.

[0052] In one embodiment, the acid used for pickling includes at least one selected from HCl, H₂SO₄, HNO₃, H₃PO₄, and HClO₄, with a concentration of 0.5–1.5 M. In another embodiment, the pickling time is 2–24 hours, including but not limited to 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 8 hours, 10 hours, 12 hours, 15 hours, 18 hours, 20 hours, or 24 hours. This invention employs suitable acid treatment conditions to remove metal elements from the catalyst, forming a hard carbon material.

[0053] According to another aspect of the present invention, the present invention also relates to a hard carbon anode material, prepared by the method for preparing the hard carbon anode material. The hard carbon anode material of the present invention has excellent discharge specific capacity and first-time efficiency; the discharge specific capacity of the anode material at a current density of 30 mA / g is above 400 mAh / g, and the first-time efficiency is greater than 90%.

[0054] According to another aspect of the present invention, the present invention also relates to a negative electrode sheet, comprising a hard carbon negative electrode material prepared by the method for preparing the hard carbon negative electrode material, or the hard carbon negative electrode material described above.

[0055] In one embodiment, the negative electrode sheet includes a negative electrode current collector and a negative electrode material layer disposed on at least one side surface of the negative electrode current collector; the negative electrode material layer contains the aforementioned hard carbon negative electrode material.

[0056] According to another aspect of the invention, the invention also relates to a battery comprising the aforementioned negative electrode.

[0057] In one embodiment, the battery of the present invention includes the aforementioned negative electrode, positive electrode, separator, and electrolyte. The battery of the present invention exhibits excellent cycle performance and rate performance.

[0058] The following explanation, in conjunction with specific embodiments, comparative examples, and accompanying drawings, further clarifies the situation.

[0059] Example 1

[0060] A method for preparing a hard carbon anode material includes the following steps:

[0061] 10g of nickel dicene and 250g of activated carbon (specific surface area 1575m²) were mixed. 2 / g, particle size 6.4μm) was placed in an intermittent kiln, kept at 150℃ for 2h in N2 atmosphere, heated to 700℃ and acetylene gas (1L / min) was introduced, and reacted for 3h to obtain the first material.

[0062] The first material was cooled to room temperature and then placed in a tube furnace under N2 atmosphere. The temperature was increased to 1400℃ at a rate of 1.5℃ / min and held for 3 hours. After cooling, the Ni impurities were removed by reacting with 10M HCl solution for 12 hours to obtain the hard carbon anode material.

[0063] Example 2

[0064] A method for preparing a hard carbon anode material includes the following steps:

[0065] 15g of nickel cadmium and 250g of bamboo charcoal activated carbon (specific surface area 1668m²) were mixed. 2 / g (particle size 8.2μm) was placed in an intermittent kiln, kept at 150℃ for 2h in N2 atmosphere, heated to 950℃ and ethane gas (1L / min) was introduced, and reacted for 4h to obtain the first material.

[0066] The first material was cooled to room temperature and placed in a tube furnace under N2 atmosphere. The temperature was increased to 1450℃ at 2℃ / min and held for 6 hours. After cooling, the Ni impurities were removed by reacting with 8M HCl solution for 18 hours to obtain the hard carbon anode material.

[0067] Example 3

[0068] A method for preparing a hard carbon anode material includes the following steps:

[0069] 10g of nickel dicene and 250g of coconut shell activated carbon (specific surface area 1564m²) were mixed. 2 / g, particle size 8.2μm) was placed in an intermittent kiln, kept at 150℃ for 2h in N2 atmosphere, heated to 950℃ and methane gas (2L / min) was introduced, and reacted for 3h to obtain the first material.

[0070] The first material was cooled to room temperature and placed in a tube furnace under N2 atmosphere. The temperature was increased to 1400℃ at 3℃ / min and held for 3 hours. After cooling, the Ni impurities were removed by reacting with 10M HCl solution for 12 hours to obtain the hard carbon anode material.

[0071] Example 4

[0072] A method for preparing a hard carbon anode material includes the following steps:

[0073] 20g of nickel dicene and 250g of coconut shell activated carbon (specific surface area 1564m²) were mixed. 2 / g, particle size 8.2μm) was placed in an intermittent kiln, kept at 150℃ for 2h in N2 atmosphere, heated to 950℃ and methane gas (2L / min) was introduced, and reacted for 3h to obtain the first material.

[0074] The first material was cooled to room temperature and placed in a tube furnace under N2 atmosphere. The temperature was increased to 1400℃ at 3℃ / min and held for 3 hours. After cooling, the Ni impurities were removed by reacting with 10M HCl solution for 12 hours to obtain the hard carbon anode material.

[0075] Example 5

[0076] A method for preparing a hard carbon anode material includes the following steps:

[0077] 30g of nickel dicene and 250g of coconut shell activated carbon (specific surface area 1564m²) were mixed. 2 / g, particle size 8.2μm) was placed in an intermittent kiln, held at 150℃ for 2 hours in a N2 atmosphere, and then heated to 950℃ before methane gas was introduced.

[0078] (2L / min), react for 3h to obtain the first material.

[0079] The first material was cooled to room temperature and placed in a tube furnace under N2 atmosphere. The temperature was increased to 1400℃ at 3℃ / min and held for 3 hours. After cooling, the Ni impurities were removed by reacting with 10M HCl solution for 12 hours to obtain the hard carbon anode material.

[0080] Example 6

[0081] A method for preparing a hard carbon anode material includes the following steps:

[0082] 40g of nickel dicene and 250g of coconut shell activated carbon (specific surface area 1564m²) were mixed. 2 / g, particle size 8.2μm) was placed in an intermittent kiln, kept at 150℃ for 2h in N2 atmosphere, heated to 950℃ and methane gas (2L / min) was introduced, and reacted for 3h to obtain the first material.

[0083] The first material was cooled to room temperature and placed in a tube furnace under N2 atmosphere. The temperature was increased to 1400℃ at 3℃ / min and held for 3 hours. After cooling, the Ni impurities were removed by reacting with 10M HCl solution for 12 hours to obtain the hard carbon anode material.

[0084] Example 7

[0085] A method for preparing a hard carbon anode material includes the following steps:

[0086] 50g of nickel dicene and 250g of coconut shell activated carbon (specific surface area 1564m²) were mixed. 2 / g, particle size 8.2μm) was placed in an intermittent kiln, kept at 150℃ for 2h in N2 atmosphere, heated to 950℃ and methane gas (2L / min) was introduced, and reacted for 3h to obtain the first material.

[0087] The first material was cooled to room temperature and placed in a tube furnace under N2 atmosphere. The temperature was increased to 1400℃ at 3℃ / min and held for 3 hours. After cooling, the Ni impurities were removed by reacting with 10M HCl solution for 12 hours to obtain the hard carbon anode material.

[0088] Example 8

[0089] A method for preparing a hard carbon anode material includes the following steps:

[0090] 20g of nickel dicene and 250g of coconut shell activated carbon (specific surface area 1564m²) were mixed. 2 / g, particle size 8.2μm) was placed in an intermittent kiln, held at 150℃ for 2 hours in a N2 atmosphere, and then heated to 600℃ before ethylene gas was introduced.

[0091] (1L / min), react for 2.5h to obtain the first material.

[0092] The first material was cooled to room temperature and placed in a tube furnace under N2 atmosphere. The temperature was increased to 1400℃ at 2.5℃ / min and held for 3 hours. After cooling, Ni impurities were removed by reacting with 6M HCl solution for 12 hours to obtain hard carbon anode material.

[0093] Example 9

[0094] A method for preparing a hard carbon anode material includes the following steps:

[0095] 20g of nickel dicene and 250g of coconut shell activated carbon (specific surface area 1564m²) were mixed. 2 / g, particle size 8.2μm) was placed in an intermittent kiln, held at 150℃ for 2 hours in a N2 atmosphere, and then heated to 600℃ before acetylene gas was introduced.

[0096] (1L / min), react for 2.5h to obtain the first material.

[0097] The first material was cooled to room temperature and placed in a tube furnace under N2 atmosphere. The temperature was increased to 1400℃ at 2.5℃ / min and held for 3 hours. After cooling, Ni impurities were removed by reacting with 6M HCl solution for 12 hours to obtain hard carbon anode material.

[0098] Example 10

[0099] A method for preparing a hard carbon anode material includes the following steps:

[0100] 20g of nickel dicene and 250g of coconut shell activated carbon (specific surface area 1564m²) were mixed. 2 / g, particle size 8.2μm) was placed in an intermittent kiln, held at 150℃ for 2 hours in a N2 atmosphere, and then heated to 950℃ before ethane gas was introduced.

[0101] (1L / min), react for 2.5h to obtain the first material.

[0102] The first material was cooled to room temperature, and the composite material was placed in a tube furnace under N2 atmosphere. The temperature was increased to 1400℃ at 2.5℃ / min and held for 3 hours. After cooling, the Ni impurities were removed by reacting with 6M HCl solution for 12 hours to obtain the hard carbon anode material.

[0103] Example 11

[0104] A method for preparing a hard carbon anode material includes the following steps:

[0105] 20g of nickel dicene and 250g of coconut shell activated carbon (specific surface area 1564m²) were mixed. 2 / g, particle size 8.2μm) was placed in an intermittent kiln, held at 150℃ for 2 hours in a N2 atmosphere, and then heated to 950℃ before methane gas was introduced.

[0106] (2L / min), react for 2.5h to obtain the first material.

[0107] The first material was cooled to room temperature and placed in a tube furnace under N2 atmosphere. The temperature was increased to 1400℃ at 2.5℃ / min and held for 3 hours. After cooling, Ni impurities were removed by reacting with 6M HCl solution for 12 hours to obtain hard carbon anode material.

[0108] Example 12

[0109] A method for preparing a hard carbon anode material includes the following steps:

[0110] 20g of nickel dicene and 250g of coconut shell activated carbon (specific surface area 1872m²) were mixed. 2 / g, particle size 7.2μm) was placed in an intermittent kiln, held at 150℃ for 2 hours in a N2 atmosphere, and then heated to 950℃ before methane gas was introduced.

[0111] (2L / min), react for 2.5h to obtain the first material.

[0112] The first material was cooled to room temperature and placed in a tube furnace under an Ar atmosphere. The temperature was increased to 1450℃ at a rate of 1.5℃ / min and held for 3 hours. After cooling, the Ni impurities were removed by reacting with an 8M H2SO4 solution for 12 hours, and the hard carbon anode material was obtained.

[0113] Example 13

[0114] A method for preparing a hard carbon anode material includes the following steps:

[0115] 20g of nickel dicene and 250g of coconut shell activated carbon (specific surface area 1789m²) were mixed. 2 / g, particle size 6.3μm) was placed in an intermittent kiln, held at 150℃ for 2 hours in a N2 atmosphere, and then heated to 950℃ before methane gas was introduced.

[0116] (2L / min), react for 2.5h to obtain the first material.

[0117] The first material was cooled to room temperature and placed in a tube furnace under an Ar atmosphere. The temperature was increased to 1450℃ at a rate of 1.5℃ / min and held for 3 hours. After cooling, the Ni impurities were removed by reacting with an 8M H2SO4 solution for 12 hours, and the hard carbon anode material was obtained.

[0118] Example 14

[0119] A method for preparing a hard carbon anode material includes the following steps:

[0120] 20g of nickel dicene and 250g of coconut shell activated carbon (specific surface area 1564m²) were mixed. 2 / g, particle size 8.2μm) is placed in an intermittent kiln, kept at 150℃ for 2h in N2 atmosphere, heated to 600℃ and ethylene gas (1L / min) is introduced, and reacted for 2h to obtain the first material.

[0121] The first material was cooled to room temperature and placed in a tube furnace under N2 atmosphere. The temperature was increased to 1300℃ at 2.5℃ / min and held for 3 hours. After cooling, Ni impurities were removed by reacting with 6M HCl solution for 12 hours to obtain hard carbon anode material.

[0122] Example 15

[0123] A method for preparing a hard carbon anode material includes the following steps:

[0124] 20g of nickel dicene and 250g of coconut shell activated carbon (specific surface area 1564m²) were mixed. 2 / g (particle size 8.2μm) was placed in an intermittent kiln, kept at 150℃ for 2h in N2 atmosphere, heated to 600℃ and ethylene gas (1L / min) was introduced, and reacted for 3h to obtain the first material.

[0125] The first material was cooled to room temperature and placed in a tube furnace under N2 atmosphere. The temperature was increased to 1400℃ at 2.5℃ / min and held for 3 hours. After cooling, Ni impurities were removed by reacting with 6M HCl solution for 12 hours to obtain hard carbon anode material.

[0126] Example 16

[0127] A method for preparing a hard carbon anode material includes the following steps:

[0128] 20g of nickel dicene and 250g of coconut shell activated carbon (specific surface area 1564m²) were mixed. 2 / g, particle size 8.2μm) was placed in an intermittent kiln, kept at 150℃ for 2h in N2 atmosphere, heated to 600℃ and ethylene gas (1L / min) was introduced, and reacted for 4h to obtain the first material.

[0129] The first material was cooled to room temperature and placed in a tube furnace under N2 atmosphere. The temperature was increased to 1400℃ at 2.5℃ / min and held for 3 hours. After cooling, Ni impurities were removed by reacting with 6M HCl solution for 12 hours to obtain hard carbon anode material.

[0130] Example 17

[0131] A method for preparing a hard carbon anode material includes the following steps:

[0132] 20g of nickel dicene and 250g of coconut shell activated carbon (specific surface area 1564m²) were mixed. 2 / g (particle size 8.2μm) was placed in an intermittent kiln, kept at 150℃ for 2h in N2 atmosphere, heated to 600℃ and ethylene gas (1L / min) was introduced, and reacted for 5h to obtain the first material.

[0133] The first material was cooled to room temperature and placed in a tube furnace under N2 atmosphere. The temperature was increased to 1400℃ at 2.5℃ / min and held for 3 hours. After cooling, Ni impurities were removed by reacting with 6M HCl solution for 12 hours to obtain hard carbon anode material.

[0134] Example 18

[0135] A method for preparing a hard carbon anode material includes the following steps:

[0136] 20g of nickel dicene and 250g of coconut shell activated carbon (specific surface area 1564m²) were mixed. 2 / g, particle size 8.2μm) was placed in an intermittent kiln, kept at 150℃ for 2h in N2 atmosphere, heated to 600℃ and ethylene gas (1L / min) was introduced, and reacted for 6h to obtain the first material.

[0137] The first material was cooled to room temperature and placed in a tube furnace under N2 atmosphere. The temperature was increased to 1300℃ at 2.5℃ / min and held for 3 hours. After cooling, Ni impurities were removed by reacting with 6M HCl solution for 12 hours to obtain hard carbon anode material.

[0138] Example 19

[0139] A method for preparing a hard carbon anode material includes the following steps:

[0140] 20g of nickel dicene and 250g of coconut shell activated carbon (specific surface area 1564m²) were mixed. 2 / g (particle size 8.2μm) was placed in an intermittent kiln, kept at 150℃ for 2h in N2 atmosphere, heated to 600℃ and ethylene gas (1L / min) was introduced, and reacted for 3h to obtain the first material.

[0141] The first material was cooled to room temperature and placed in a tube furnace under N2 atmosphere. The temperature was increased to 1350℃ at 2.5℃ / min and held for 3 hours. After cooling, Ni impurities were removed by reacting with 6M HCl solution for 12 hours to obtain hard carbon anode material.

[0142] Example 20

[0143] A method for preparing a hard carbon anode material includes the following steps:

[0144] 20g of nickel dicene and 250g of coconut shell activated carbon (specific surface area 1564m²) were mixed. 2 / g (particle size 8.2μm) was placed in an intermittent kiln, kept at 150℃ for 2h in N2 atmosphere, heated to 600℃ and ethylene gas (1L / min) was introduced, and reacted for 3h to obtain the first material.

[0145] The first material was cooled to room temperature and placed in a tube furnace under N2 atmosphere. The temperature was increased to 1400℃ at 2.5℃ / min and held for 3 hours. After cooling, Ni impurities were removed by reacting with 6M HCl solution for 12 hours to obtain hard carbon anode material.

[0146] Example 21

[0147] A method for preparing a hard carbon anode material includes the following steps:

[0148] 20g of nickel dicene and 250g of coconut shell activated carbon (specific surface area 1564m²) were mixed. 2 / g (particle size 8.2μm) was placed in an intermittent kiln, kept at 150℃ for 2h in N2 atmosphere, heated to 600℃ and ethylene gas (1L / min) was introduced, and reacted for 3h to obtain the first material.

[0149] The first material was cooled to room temperature, and the composite material was placed in a tube furnace under N2 atmosphere. The temperature was increased to 1450℃ at 2.5℃ / min and held for 3 hours. After cooling, the Ni impurities were removed by reacting with 6M HCl solution for 12 hours to obtain the hard carbon anode material.

[0150] Example 22

[0151] A method for preparing a hard carbon anode material includes the following steps:

[0152] 20g of nickel dicene and 250g of coconut shell activated carbon (specific surface area 1564m²) were mixed. 2 / g (particle size 8.2μm) was placed in an intermittent kiln, kept at 150℃ for 2h in N2 atmosphere, heated to 600℃ and ethylene gas (1L / min) was introduced, and reacted for 3h to obtain the first material.

[0153] The first material was cooled to room temperature and placed in a tube furnace under N2 atmosphere. The temperature was increased to 1500℃ at 2.5℃ / min and held for 3 hours. After cooling, Ni impurities were removed by reacting with 6M HCl solution for 12 hours to obtain hard carbon anode material.

[0154] Example 23

[0155] A method for preparing a hard carbon anode material includes the following steps:

[0156] 20g of nickel dicene and 250g of coconut shell activated carbon (specific surface area 1564m²) were mixed.2 / g, particle size 8.2μm) was placed in an intermittent kiln and kept at 150℃ for 2h in N2 atmosphere. Then it was heated to 600℃ and methane-ethylene gas (flow rates of 1L / min (methane) and 0.5L / min (ethylene)) was introduced. The reaction was carried out for 3h to obtain the first material.

[0157] The first material was cooled to room temperature and placed in a tube furnace under N2 atmosphere. The temperature was increased to 1400℃ at 2.5℃ / min and held for 3 hours. After cooling, Ni impurities were removed by reacting with 6M HCl solution for 12 hours to obtain hard carbon anode material.

[0158] Example 24

[0159] A method for preparing a hard carbon anode material includes the following steps:

[0160] 20g of nickel dicene and 250g of walnut shell activated carbon (specific surface area 1578m²) were mixed. 2 / g, particle size 6μm) was placed in an intermittent kiln and kept at 150℃ for 2h in N2 atmosphere. Then it was heated to 950℃ and methane-acetylene gas (flow rates of 1L / min (methane) and 0.5L / min (acetylene) respectively) was introduced. The reaction was carried out for 2h to obtain the first material.

[0161] The first material was cooled to room temperature and placed in a tube furnace under N2 atmosphere. The temperature was increased to 1400℃ at 0.5℃ / min and held for 3 hours. After cooling, the Ni impurities were removed by reacting with 5M HNO3 solution for 18 hours to obtain the hard carbon anode material.

[0162] Comparative Example 1

[0163] The preparation method of hard carbon anode material is the same as in Example 12, except that nickel dicerocene is not added.

[0164] Experimental Example

[0165] Sodium-ion batteries were prepared using the negative electrode materials obtained in each embodiment and comparative example, specifically including:

[0166] Preparation of hard carbon electrode: Hard carbon negative electrode material (94%), conductive agent SP (2%), binder CMC (1.5%), SBR (2.5%) and deionized water (solid content 40%) were mixed and stirred, and uniformly coated on aluminum foil. The water was removed under vacuum at 100°C. The dried electrode was punched to obtain hard carbon electrode. In a glove box, a button cell was assembled with hard carbon electrode as negative electrode and sodium sheet as positive electrode. The electrolyte was 1M NaFP6 dissolved in EC:DMC (volume ratio 1:1). The separator was Celgard 2400, and electrochemical tests were performed.

[0167] The batteries obtained from the negative electrode materials of each embodiment and comparative example at 30 mA g-1 The test results of the initial discharge specific capacity and initial efficiency at current density are shown in Table 1. The electrochemical performance diagram of the negative electrode material in Example 2 is shown in... Figure 1 As shown.

[0168] Table 1 Test Results

[0169]

[0170]

[0171] As shown in Table 1, the battery prepared by further processing the hard carbon anode material obtained by the method of the present invention has excellent discharge specific capacity and first-time efficiency, which are superior to the discharge specific capacity and first-time efficiency of the battery prepared by the anode material in Comparative Example 1.

[0172] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a hard carbon anode material, characterized in that, Includes the following steps: A mixture of organometallic catalyst and biomass activated carbon is subjected to a first heat treatment, then a gaseous carbon source is introduced and a second heat treatment is performed to obtain a first material. The first material is then subjected to carbonization and acid washing. The organometallic catalyst includes nickel dicerocene; The mass of the organometallic catalyst is 1% to 20% of the mass of the biomass activated carbon; The temperature of the first heat treatment is 140~180℃, and the time of the first heat treatment is 1~3h; The carbonization treatment temperature is 1250~1550℃, and the carbonization treatment time is 2~8h.

2. The method for preparing the hard carbon anode material according to claim 1, characterized in that, It includes at least one of the following features (1) to (2): (1) The biomass activated carbon includes at least one of bamboo charcoal activated carbon, wood charcoal activated carbon, coconut shell activated carbon and walnut shell activated carbon; (2) The specific surface area of ​​the biomass activated carbon is 1550~2000 m². 2 / g, with a particle size of 5~10μm.

3. The method for preparing the hard carbon anode material according to claim 1, characterized in that, It includes at least one of the following features (1) to (2): (1) The gaseous carbon source includes at least one of methane, ethane, propane, acetylene, ethylene, propylene and toluene; (2) The gaseous carbon source deposits carbon material in the pores of the biomass activated carbon by gas phase deposition, and the mass of the carbon material is 5% to 60% of the mass of the biomass activated carbon.

4. The method for preparing the hard carbon anode material according to claim 1, characterized in that, The first heat treatment was carried out under protective gas conditions.

5. The method for preparing the hard carbon anode material according to claim 1, characterized in that, It includes at least one of the following features (1) to (3): (1) The temperature of the second heat treatment is 600~1000℃, and the time of the second heat treatment is 0.5~6h; (2) The second heat treatment is carried out under protective gas conditions; (3) The heating rate of the second heat treatment is 0.5~10℃ / min.

6. The method for preparing the hard carbon anode material according to claim 1, characterized in that, It includes at least one of the following features (1) to (2): (1) The carbonization process is carried out under protective gas conditions; (2) The heating rate of the carbonization process is 0.5~10℃ / min.

7. The method for preparing the hard carbon anode material according to claim 1, characterized in that, It includes at least one of the following features (1) to (2): (1) The acid used in the pickling treatment includes at least one of HCl, H2SO4, HNO3, H3PO4 and HClO4; (2) The pickling time is 2~24h.

8. A hard carbon anode material, characterized in that, The hard carbon anode material is prepared by the method described in any one of claims 1 to 7. The hard carbon anode material has a discharge specific capacity of over 400 mAh / g at a current density of 30 mA / g, and an initial efficiency of over 90%.

9. A negative electrode sheet, characterized in that, The hard carbon anode material prepared by the method of any one of claims 1 to 7, or the hard carbon anode material as described in claim 8.

10. A battery, characterized in that, Includes the negative electrode sheet as described in claim 9.

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