Petroleum coke-based sodium negative electrode material, application thereof and sodium-ion secondary battery

Abstract

The application provides a petroleum coke-based sodium electric negative electrode material and application and a sodium ion secondary battery, and belongs to the technical field of electrode materials.The petroleum coke-based sodium electric negative electrode material is prepared from petroleum coke material through solid alkali activation treatment, washing and sintering in sequence; the true density of the petroleum coke-based sodium electric negative electrode material is 1.6-1.8 g / cm 3 , the specific surface area is 5-30 m 2 / g, and the intensity ratio I D / I G of the scattering peak in the Raman spectrum is 1.00-1.25.The petroleum coke-based sodium electric negative electrode material is prepared from petroleum coke material, has low cost, and has excellent electrochemical performance, and is suitable for being used as a sodium ion secondary battery negative electrode material.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of electrode materials, in particular to a petroleum coke-based sodium negative electrode material and application thereof and a sodium-ion secondary battery. BACKGROUND

[0002] Since the beginning of the 21st century, due to the overexploitation and utilization of fossil energy such as coal and petroleum by human beings in the early stage, energy shortage and environmental pollution have become two serious problems faced by the world, which urgently requires people to find sustainable and renewable new energy to replace traditional energy. In this context, the development of renewable energy has become a top priority for all countries. Solar energy, wind energy, tidal energy, geothermal energy, ocean energy and hydrogen energy have gradually attracted people's attention. In recent years, in the world, renewable energy such as wind energy and solar energy has developed rapidly, and the installed capacity has also increased year by year. Taking photovoltaic power generation as an example, about 81GW of photovoltaic power was newly installed in the world in 2017, and the cumulative installed capacity was about 390GW, which was roughly equivalent to the global nuclear power installed capacity. However, renewable energy such as wind energy and solar energy is greatly affected by weather and climate, and its energy output has problems such as discontinuity and instability, which brings great challenges to its grid connection and grid integration. At present, renewable energy such as wind energy and solar energy cannot be directly connected to the grid, which has caused the frequent phenomenon of abandoned wind and light in recent years, resulting in great energy waste and serious economic losses.

[0003] Large-capacity energy storage technology is the most effective method to solve such problems. For a long time, the electrochemical energy storage system represented by lithium ion batteries has been unique in the field of energy storage due to its high working voltage, large energy density and power density, good safety performance and other advantages, and has been widely used in portable electronic products and electric vehicles. However, the limited reserves and uneven distribution of lithium make the price of lithium ion batteries relatively high, and frequent charging and discharging can easily reduce the service life, resulting in high overall investment cost; more seriously, the price of lithium resources has been rising in recent years, and the price of lithium ion batteries has also soared, making it difficult to be the main force in the future large-scale energy storage field. The alkali metal element sodium, which is homologous with lithium, has similar properties to lithium, and is abundant in reserves and low in cost. In addition, the current collector of the negative electrode of the sodium-ion battery can be replaced by aluminum foil instead of the high-cost copper foil, further reducing the cost, so the sodium-ion battery has great advantages in resources and cost, and has greater application potential in the field of large-scale energy storage.

[0004] The radius of sodium ion (0.102 nm) is larger than that of lithium ion (0.069 nm), so the practical lithium ion battery negative electrode material graphite cannot be directly used as a sodium ion battery negative electrode material: lithium ions can be embedded into graphite interlayers to form a first-order intercalation compound LiC6 and have good electrochemical performance, but graphite cannot de-embed sodium ions. Therefore, finding a suitable negative electrode material has become the key to the development of sodium ion batteries. Specifically, an excellent sodium ion negative electrode should meet the following requirements: (1) the sodium de-embedding potential is low, which is beneficial to matching with high potential positive electrode materials to achieve high energy density; (2) the sodium de-embedding polarization is small, which is beneficial to large current charging and discharging; (3) the chemical properties in the electrolyte remain stable, and the structural stability is good in the electrochemical reaction process, so that a long cycle life can be achieved; (4) there is an advantage of resource and cost, and the material resource is abundant and the price is low. From the current research, hard carbon material has a good application prospect as a sodium ion battery negative electrode material, but the existing hard carbon material is mainly biomass hard carbon material, which has a high cost. SUMMARY

[0005] The petroleum coke-based sodium battery negative electrode material and the sodium ion secondary battery provided by the application have low cost and excellent electrochemical performance, and are suitable for use as a sodium ion secondary battery negative electrode material.

[0006] In order to achieve the above-mentioned application purposes, the application provides the following technical solutions.

[0007] The petroleum coke-based sodium battery negative electrode material is prepared from petroleum coke material through solid alkali activation treatment, washing and sintering in sequence. 3 The true density of the petroleum coke-based sodium battery negative electrode material is 1.6-1.8 g / cm 2 The specific surface area is 5-30 m D / g, and the intensity ratio I G / I

[0008] Preferably, the petroleum coke material includes one or more of needle coke, shot coke, spherical coke, sponge coke and powder coke.

[0009] Preferably, the mass ratio of the petroleum coke material to the solid alkali in the solid alkali activation treatment process is 1:(1-20).

[0010] Preferably, the solid alkali is an alkali metal hydroxide and / or an alkaline earth metal hydroxide.

[0011] Preferably, the temperature of the solid alkali activation treatment is 500-900℃, and the holding time is 2-10 h.

[0012] Preferably, the washing comprises one or more of neutral solvent washing, acid washing and alkali washing.

[0013] Preferably, the sintering temperature is 1000-1600 DEG C, and the holding time is 2-10 h.

[0014] Preferably, the petroleum coke-based sodium electric negative electrode material has a carbon layer spacing of 0.34-0.42 nm.

[0015] The application provides application of the petroleum coke-based sodium electric negative electrode material in a sodium ion secondary battery negative electrode material.

[0016] The application provides a sodium ion secondary battery, wherein the negative electrode material of the sodium ion secondary battery is the petroleum coke-based sodium electric negative electrode material.

[0017] The application provides a petroleum coke-based sodium electric negative electrode material, which is prepared by sequentially subjecting petroleum coke material to solid alkali activation treatment, washing and sintering. 3 The petroleum coke-based sodium electric negative electrode material has a true density of 1.6-1.8 g / cm 2 , a specific surface area of 5-30 m D / g, and a ratio of scattering peak intensity I G / I D of 1.00-1.25. The petroleum coke-based sodium electric negative electrode material has a high reversible capacity, and the charge-discharge curve is "slope+platform", and both the slope capacity and the platform capacity are high. Meanwhile, compared with the biomass hard carbon material, the method provided by the application uses petroleum coke material as raw material, which is cheap, and the tap density and the compacted density of the petroleum coke material are higher than those of the biomass raw material, which is beneficial to application in the sodium ion secondary battery. In addition, the petroleum coke-based sodium electric negative electrode material provided by the application has a mature preparation process and equipment, and is suitable for large-scale production. The results of the examples show that the petroleum coke-based sodium electric negative electrode material provided by the application has a high initial reversible capacity and initial coulombic efficiency, and in the sodium ion battery test system, the initial reversible capacity is 255-306 mAh / g, and the initial coulombic efficiency is 79-90%; moreover, the petroleum coke-based sodium electric negative electrode material is relatively stable in the rate cycle process, and the coulombic efficiency fluctuation is small; with the increase of the sintering temperature, the I G / I of the petroleum coke-based sodium electric negative electrode material decreases.The small amorphous carbon has reduced disorder degree, reduced specific surface area and increased closed pores; compared with the petroleum coke-based sodium electric negative electrode material without solid alkali activation treatment and washing, the petroleum coke-based sodium electric negative electrode material provided by the application has reduced ramp capacity and increased platform capacity, wherein the ramp capacity is 153-173 mAh / g, and the platform capacity is 102-150 mAh / g, which indicates that the sodium storage capacity in the ramp region of the amorphous carbon comes from the adsorption of sodium ions at defect positions, and the sodium storage performance of the petroleum coke-based sodium electric negative electrode material is improved to a certain extent. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 SEM image (30000x) of the petroleum coke-based sodium electric negative electrode material prepared for Example 1;

[0019] Figure 2 SEM image (10000x) of the petroleum coke-based sodium electric negative electrode material prepared for Example 1;

[0020] Figure 3 XRD image of the petroleum coke-based sodium electric negative electrode material prepared for Example 1. DETAILED DESCRIPTION

[0021] The application provides a petroleum coke-based sodium electric negative electrode material, which is prepared from a petroleum coke material through solid alkali activation treatment, washing and sintering in sequence; the true density of the petroleum coke-based sodium electric negative electrode material is 1.6-1.8 g / cm 3 , the specific surface area is 5-30 m 2 / g, the intensity ratio I D / I G of the scattering peak in the Raman spectrum is 1.00-1.25.

[0022] The petroleum coke material is subjected to solid base activation treatment to obtain an activated carbon material. In the present application, the petroleum coke material preferably comprises one or more of needle coke, shot coke, spheroidal coke, sponge coke and powder coke, more preferably needle coke or shot coke. In the present application, the solid base used in the solid base activation treatment is preferably an alkali metal hydroxide and / or an alkaline earth metal hydroxide, the alkali metal hydroxide is preferably one or more of sodium hydroxide, lithium hydroxide and potassium hydroxide, and the alkaline earth metal hydroxide is preferably calcium hydroxide. In the present application, the mass ratio of the petroleum coke material to the solid base is preferably 1:(0.5-20), more preferably 1:(0.5-5), and further preferably 1:(0.5-1). In the present application, the petroleum coke material is preferably passed through a 325 mesh screen before being mixed with the solid base. In the present application, the petroleum coke material and the solid base are preferably mixed by adding the petroleum coke material and the solid base into a small steel mill, crushing and mixing for 10 minutes in three times, to obtain a mixture; the particle size D50 of the mixture is preferably 3-15 μm. In the present application, the temperature of the solid base activation treatment is preferably 500-900℃, more preferably 600-850℃, further preferably 750-850℃, and more preferably 810-850℃; the holding time is preferably 2-10 h, more preferably 2-6 h, and further preferably 2-3 h. In the present application, the solid base activation treatment can be carried out in an oxygen-containing atmosphere or in an oxygen-free atmosphere; the gas providing the oxygen-containing atmosphere can be air or a mixture of air and protective gas; the gas providing the oxygen-free atmosphere is preferably a protective gas; the protective gas preferably comprises nitrogen, helium, neon or argon; the gas flow rate of the protective gas is preferably ≤200 mL / min, and more preferably 100-200 mL / min; when the solid base activation treatment is carried out in a mixture of air and protective gas, the volume ratio of the air to the protective gas is preferably 1:(1-10), and more preferably 1:(5-10). In the present application, the petroleum coke material and the solid base are preferably mixed in a graphite crucible, and then transferred to a tube furnace or a box furnace for solid base activation treatment. In the present application, during the solid base activation treatment, the solid base can destroy the microstructure of the petroleum coke, introduce more open pore structures in the carbon layer structure, and after washing and sintering at high temperature, hinder the ordered rearrangement of the aromatic structure of the petroleum coke material, form more closed pores in the carbon layer structure, and use the obtained petroleum coke-based sodium negative electrode material as a sodium ion secondary battery negative electrode material, which has a high reversible capacity.

[0023] After the solid base activation treatment, the activated carbon material is washed to obtain a purified carbon material. In the present application, the washing preferably comprises one or more of neutral solvent washing, acid washing and alkali washing, and can specifically be alkali washing, neutral solvent washing and acid washing in sequence, or neutral solvent washing, acid washing and neutral solvent washing in sequence. In the present application, the neutral solvent used in the neutral solvent washing preferably comprises one or more of water, anhydrous ethanol and isopropyl alcohol, and the water is preferably pure water. In the present application, the acid washing solution used in the acid washing is preferably one or more of hydrofluoric acid, sulfurous acid, phosphoric acid, nitrous acid, sulfuric acid, hydrochloric acid and nitric acid, and is more preferably hydrochloric acid or nitric acid; when two acid washing solutions are used, the volume ratio of the two acid washing solutions is preferably (1-20):(1-20); and the concentration of the acid washing solution is preferably 0.5-5 mol / L, and is more preferably 1-2 mol / L. In the present application, the alkali washing solution used in the alkali washing is preferably one or more of sodium hydroxide solution, lithium hydroxide solution, calcium hydroxide solution and potassium hydroxide solution; when two alkali washing solutions are used, the volume ratio of the two alkali washing solutions is preferably (1-20):(1-20); and the concentration of the alkali washing solution is preferably 0.5-5 mol / L, and is more preferably 1-2 mol / L.

[0024] Preferably, the activated carbon material obtained after the solid base activation treatment is quickly poured into a neutral solvent, and first neutral solvent washing is performed under stirring, then solid-liquid separation is performed, the obtained solid material is washed with a second neutral solvent until the pH value is less than 9 to obtain a neutral solvent washed carbon material; the neutral solvent washed carbon material is mixed with an acid reagent, and acid washing is performed under heating, then solid-liquid separation is performed to obtain an acid washed carbon material; the acid washed carbon material is washed with a third neutral solvent until the pH value is greater than 6, and finally dried to obtain a purified carbon material. In the present application, the stirring is preferably magnetic stirring, and the stirring time is preferably 50-70 min, and is more preferably 60 min; and the solid-liquid separation is preferably filtration. In the present application, the heating temperature is preferably 75-85℃, and is more preferably 80℃; and the heating time is preferably 1-3 h, and is more preferably 2 h. In the present application, the drying temperature is preferably 75-85℃, and is more preferably 80℃; the drying time is preferably 10-15 h, and is more preferably 12 h; and the drying is preferably performed in a blast drying oven. The present application can better open the pores through washing, which is conducive to the formation of closed pores in the subsequent sintering step.

[0025] After obtaining the purified carbon material, the present invention sintersulates the purified carbon material to obtain a petroleum coke-based sodium electrode anode material. In the present invention, the sintering temperature is preferably 1000–1600℃, more preferably 1200–1400℃; the sintering holding time is preferably 2–10 h, more preferably 3–8 h, and even more preferably 3–4 h. In the present invention, the heating rate to the required sintering temperature is preferably 2–4℃ / min, more preferably 3℃ / min. In the present invention, the sintering can be carried out in an oxygen-containing atmosphere or an oxygen-free atmosphere; the gas providing the oxygen-containing atmosphere can be air or a mixture of air and a protective gas; the gas providing the oxygen-free atmosphere is preferably a protective gas; the protective gas preferably includes nitrogen, helium, neon, or argon; the flow rate of the protective gas is preferably ≤200 mL / min, more preferably 30–60 mL / min. After sintering, the present invention preferably cools the material to 600°C at a rate of 2-4°C / min (more preferably 3°C / min), and then allows it to cool naturally to room temperature to obtain a petroleum coke-based sodium-ion battery anode material. The present invention preferably performs sintering under the above conditions to form closed pores in the carbon layer structure of the obtained petroleum coke-based sodium-ion battery anode material, reducing the specific surface area. Using the obtained petroleum coke-based sodium-ion battery anode material as a sodium-ion secondary battery anode material can improve reversible capacity and initial coulombic efficiency, giving the sodium-ion secondary battery better cycle performance.

[0026] In this invention, the true density of the petroleum coke-based sodium electrode material is 1.6–1.8 g / cm³. 3 The preferred value is 1.61–1.78 g / cm³. 3 More preferably, it is 1.62–1.76 g / cm³. 3 More preferably, it is 1.63–1.75 g / cm³. 3 Specific surface area is 5–30 m² 2 / g, preferably 6.5~20m 2 / g, more preferably 10–15.5m 2 / g. In this invention, the intensity of the scattering peak in the Raman spectrum of the petroleum coke-based sodium electrode material is higher than that of I. D / I G Preferably, it is 1.00 to 1.25, more preferably 1.02 to 1.23, and even more preferably 1.11 to 1.18; in this invention, in the Raman spectrum of the petroleum coke-based sodium electrode material after separation and measurement, the petroleum coke-based sodium electrode material at 1300 cm⁻¹... -1 With 1580cm -1 The scattering peak at this point corresponds to the Raman characteristic peaks D-peak and G-peak of C atomic crystal, and the intensity ratio of the two is denoted as I. D / I GIn the present application, the carbon layer spacing of the petroleum coke-based sodium electric negative electrode material is preferably 0.34-0.42 nm, more preferably 0.35-0.40 nm, and further preferably 0.36-0.38 nm; and the particle size D50 is preferably 3-1000 μm, and more preferably 3-15 μm. In the present application, the content of carbon element in the petroleum coke-based sodium electric negative electrode material is preferably 95 wt% or more, and more preferably 99 wt%; and the petroleum coke-based sodium electric negative electrode material further comprises a small amount of other elements, such as Si, O, Ca, etc.

[0027] The present application provides the application of the petroleum coke-based sodium electric negative electrode material in the negative electrode material of a sodium ion secondary battery.

[0028] The present application provides a sodium ion secondary battery, wherein the negative electrode material of the sodium ion secondary battery is the petroleum coke-based sodium electric negative electrode material. The present application does not have special limitations on the specific composition and structure of the sodium ion secondary electrode, and the composition and structure known to those skilled in the art can be used.

[0029] The technical solutions in the present application will be clearly and completely described below in combination with the embodiments in the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0030] Embodiment 1

[0031] 200 g of petroleum coke (specifically, shot coke, passing through a 325 mesh screen) and 100 g of potassium hydroxide were added to a small steel mill, and were pulverized and mixed for 10 min in 3 times of cumulative crushing, to obtain a mixture (particle size D50 of 3-15 μm); 50 g of the mixture was weighed and placed in a graphite crucible, and was transferred to a tube furnace, argon was passed at a flow rate of 200 mL / min, and the temperature was raised from room temperature (25℃) to 850℃ at a temperature raising rate of 3℃ / min, and was kept for 2 h for solid alkali activation treatment, and then was naturally cooled to room temperature, and was discharged from the tube furnace, to obtain an activated carbon material;

[0032] The activated carbon material after discharging was quickly poured into 500 mL of pure water, and was magnetically stirred for 1 h, and then was suction filtered, and the obtained solid material was washed with pure water until the pH value of the filtrate was <9, and the obtained water-washed material was placed in a beaker, 200 mL of hydrochloric acid with a concentration of 2 mol / L was added, and was magnetically stirred for 10 min, and then was transferred into an oil bath, and was kept for 2 h at 80℃ for acid treatment, and then was suction filtered, and the obtained solid material was washed with pure water until the pH value of the filtrate was >6, and the obtained water-washed material was transferred into a blast drying oven, and was dried at 80℃ for 12 h, to obtain a purified carbon material;

[0033] 20 g of the purified carbon material was weighed into a graphite crucible and transferred to a tube furnace. Argon was passed at a flow rate of 60 mL / min, and the temperature was raised from room temperature to 1200°C at a rate of 3°C / min. Sintering was performed at 1200°C for 3 h, and then the temperature was lowered to 600°C at a rate of 3°C / min. Finally, the temperature was lowered to room temperature naturally. A petroleum coke-based sodium electric negative electrode material was obtained, which was designated as sample 1.

[0034] Example 2

[0035] A petroleum coke-based sodium electric negative electrode material was prepared according to the method of Example 1, except that the sintering temperature was 1000°C. The final petroleum coke-based sodium electric negative electrode material was designated as sample 2.

[0036] Example 3

[0037] A petroleum coke-based sodium electric negative electrode material was prepared according to the method of Example 1, except that the sintering temperature was 1400°C. The final petroleum coke-based sodium electric negative electrode material was designated as sample 3.

[0038] Example 4

[0039] A petroleum coke-based sodium electric negative electrode material was prepared according to the method of Example 1, except that the sintering temperature was 1600°C. The final petroleum coke-based sodium electric negative electrode material was designated as sample 4.

[0040] Comparative Example 1

[0041] Petroleum coke (specifically, shot coke, which was passed through a 325 mesh screen) was directly sintered. Specifically, the petroleum coke was placed in a graphite crucible and transferred to a tube furnace. Argon was passed at a flow rate of 60 mL / min, and the temperature was raised from room temperature to 1200°C at a rate of 3°C / min. Sintering was performed at 1200°C for 3 h, and then the temperature was lowered to 600°C at a rate of 3°C / min. Finally, the temperature was lowered to room temperature naturally. The petroleum coke-based sodium electric negative electrode material obtained was designated as sample 5.

[0042] Comparative Example 2

[0043] A petroleum coke-based sodium electric negative electrode material was prepared according to the method of Example 1, except that no washing was performed. Specifically, the activated carbon material after being discharged from the furnace was directly sintered. The final petroleum coke-based sodium electric negative electrode material was designated as sample 6.

[0044] Comparative Example 3

[0045] 200g petroleum coke (specifically, shot coke, passed through a 325 mesh screen) was mixed with 1L of a 10% by mass potassium hydroxide aqueous solution, soaked at room temperature for 2h, and then subjected to solid-liquid separation. The obtained solid material was dried and then placed in a graphite crucible, transferred to a tube furnace, and subjected to sintering at 850℃ for 2h at a temperature increase rate of 3℃ / min from room temperature (25℃) under argon gas flow of 200mL / min. After the sintering, the tube furnace was naturally cooled to room temperature, and the activated carbon material was discharged from the tube furnace.

[0046] The activated carbon material was used to prepare a petroleum coke-based sodium battery negative electrode material according to the method of Example 1, and is referred to as sample 7.

[0047] Characterization and performance testing

[0048] The petroleum coke-based sodium battery negative electrode material prepared in Example 1 was characterized, as follows.

[0049] Figure 1 The SEM image (30000x) of the petroleum coke-based sodium battery negative electrode material prepared in Example 1 is shown in Figure 1. Figure 1 As can be seen, the surface of the petroleum coke-based sodium battery negative electrode material obtained by treating petroleum coke according to the method of the present application is relatively rough.

[0050] Figure 2 The SEM image (10000x) of the petroleum coke-based sodium battery negative electrode material prepared in Example 1 is shown in Figure 2. Figure 2 As can be seen, the petroleum coke-based sodium battery negative electrode material has good particle uniformity.

[0051] Figure 3 The XRD pattern of the petroleum coke-based sodium battery negative electrode material prepared in Example 1 is shown in Figure 3. Figure 3 As can be seen, the D(002) peak of the carbon material prepared in Example 1 is about 23.9, which is a hard carbon structure.

[0052] The petroleum coke-based sodium battery negative electrode materials prepared in Examples 1-4 and Comparative Examples 1-2 were subjected to electrochemical performance testing, as follows.

[0053] The electrochemical performance testing was performed using a CR2032 button half-cell. Specifically, the petroleum coke-based sodium battery negative electrode material, SuperP and PVDF were mixed at a mass ratio of 90:5:5, and then stirred in N-methyl pyrrolidone (NMP) to form a slurry. The slurry was coated on an aluminum foil, dried, and then punched into a circular electrode with a diameter of 12mm. The loading amount of the petroleum coke-based sodium battery negative electrode material was 2mg / cm 2The sodium ion CR2032 button half-cell is assembled by using the pole piece, the voltage range is 0-2V, and in the 0.1C small rate cycle process, after discharging to the cut-off voltage, 10min is kept, then discharged to 0V at the rate of 0.02C, and then 0.1C charging process is carried out.

[0054] Table 1 is the characterization results and electrochemical performance test results of the petroleum coke-based sodium electric negative electrode materials prepared in examples 1-4 and comparative examples 1-2, wherein, I D / I G According to the Raman calculation, the slope capacity and the platform capacity are obtained according to the charge-discharge curve of the sodium ion CR2032 button half-cell. As shown in Table 1, compared with comparative example 1, the petroleum coke-based sodium electric negative electrode material prepared by using the solid alkali activation treatment technology to treat the petroleum coke in the examples of the application is used in the sodium ion CR2032 button half-cell, the capacity retention rate of the first 50 cycles and the reversible capacity retention rate relative to 0.1C are improved; and the data of the examples of the application show that, with the increase of the sintering temperature, the I D / I G of the petroleum coke-based sodium electric negative electrode material becomes smaller, the disorder degree of the amorphous carbon is reduced, the specific surface area is reduced, and the closed pores are increased; at the same time, compared with comparative example 1, the slope capacity of the petroleum coke-based sodium electric negative electrode material in the examples of the application is reduced, and the platform capacity is increased, which indicates that the sodium storage capacity in the slope region of the amorphous carbon comes from the adsorption of sodium ions in the defect position, and the sodium storage performance of the petroleum coke-based sodium electric negative electrode material is improved to a certain extent. In addition, compared with comparative example 2, the first coulombic efficiency of the petroleum coke-based sodium electric negative electrode material in the examples of the application is greatly improved, and the cycle performance is obviously better; compared with comparative example 3, the first reversible capacity, the first coulombic efficiency and the capacity retention rate relative to 0.1C of the reversible capacity and other cycle effects of the petroleum coke-based sodium electric negative electrode material in the examples of the application are greatly improved, the solid alkali in the examples of the application can be directly mixed with the petroleum coke material for high-temperature treatment, which is convenient to operate and does not obviously damage the particle structure, and the reaction is mild; however, if the liquid alkali is used for treatment, it will penetrate into the particles in the aqueous solution by using the concentration gradient, which will damage the particle surface and affect the performance of the finally obtained petroleum coke-based sodium electric negative electrode material, and the treatment by using the liquid alkali is also destructive to the equipment. Table 1 is the characterization results and electrochemical performance test results of the petroleum coke-based sodium electric negative electrode materials prepared in examples 1-4 and comparative examples 1-3

[0055]

[0056] The above only describes the preferred embodiments of the application, and it should be pointed out that, for ordinary skilled persons in the art, some improvements and refinements can be made without departing from the principles of the application, and these improvements and refinements should also be regarded as the protection scope of the application.

Claims

1. A petroleum coke-based sodium electric negative electrode material, which is prepared by sequentially subjecting a petroleum coke material to solid alkali activation treatment, washing, and sintering; the solid alkali is potassium hydroxide, and the mass ratio of the petroleum coke material to the solid alkali during the solid alkali activation treatment is 1: (0.5-1); the sintering temperature is 1000-1600℃, and the holding time is 2-10h. The petroleum coke-based sodium negative electrode material has a true density of 1.6-1.8 g / cm 3 , a specific surface area of 5-30 m 2 / g, and an intensity ratio I D / I G of the scattering peaks in the Raman spectrum of 1.00-1.

25.

2. The petroleum coke-based sodium negative electrode material according to claim 1, characterized in that, The petroleum coke material comprises one or more of needle coke, spherical coke, sponge coke, and powder coke.

3. The petroleum coke-based sodium negative electrode material according to claim 1, characterized in that, The solid alkali activation treatment temperature is 500-900℃, and the holding time is 2-10h.

4. The petroleum coke-based sodium negative electrode material of claim 1, wherein, The washing comprises one or more of neutral solvent washing, acid washing, and alkali washing.

5. The petroleum coke-based sodium negative electrode material of claim 1, wherein, The interlayer spacing of the carbon layer of the petroleum coke-based sodium electric negative electrode material is 0.34-0.42nm.

6. Use of the petroleum coke-based sodium electric negative electrode material according to any one of claims 1-5 in a sodium-ion secondary battery negative electrode material.

7. A sodium-ion secondary battery, characterized by, The negative electrode material is the petroleum coke-based sodium electric negative electrode material according to any one of claims 1-5.

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