Resin-based hard carbon material, method for preparing the same, and battery

Abstract

This invention provides a resin-based hard carbon material, its preparation method, and a battery. The resin-based hard carbon material has a porous structure, including micropores and ultramicropores; the pore size distribution of the ultramicropores is <0.7 nm, and the pore size distribution of the micropores is 0.7–2 nm (excluding 2 nm); zinc is also attached to the pore walls. The resin-based hard carbon provided by this invention has narrow, uniform, and dense pores, possessing both micropores and abundant ultramicropores, which is beneficial for lithium-ion storage. Furthermore, the ultramicropores isolate the entry of electrolyte, avoiding excessive side reactions and irreversible capacity buildup while achieving lithium-ion storage. It also retains the high-rate performance characteristics of hard carbon materials. The zinc in the pores also has a lithiophilic effect, further attracting lithium ions into the pores, thus achieving the goal of improving the capacity and first-time efficiency of hard carbon materials while maintaining high-rate performance.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, and relates to a resin-based hard carbon material, its preparation method, and a battery, particularly to a resin-based hard carbon material more suitable for lithium-ion batteries, its preparation method, and a lithium-ion battery. Background Technology

[0002] Batteries, as crucial energy storage devices, have become ubiquitous in various applications, from small electronic devices to large electric vehicles and heavy equipment. The continued growth of the electric vehicle market has reduced greenhouse gas emissions, but this also places higher demands on battery performance. Currently, lithium-ion batteries dominate these applications, and commercially available graphite anodes, which determine their performance, possess high energy density and cycle life. However, graphite anodes have reached their theoretical capacity, limiting their ability to further improve electric vehicle range. Furthermore, graphite's rate performance is poor, failing to achieve ideal charging speeds. The main bottleneck lies in graphite's slow intercalation kinetics, increased polarization at high current densities, and slow lithium-ion diffusion, hindering rapid and stable charging and discharging and impeding its application in high-power and high-energy-density energy storage systems. Therefore, extensive research is currently focused on developing alternatives to address graphite's shortcomings.

[0003] Current research indicates that hard carbon materials possess a disordered structure and large interlayer spacing. The randomly stacked layers also generate nanopores, enabling efficient lithium-ion storage and rapid diffusion. However, for lithium-ion batteries, hard carbon, when used as an anode, suffers from low initial efficiency and high irreversible capacity, hindering effective lithium storage and requiring further capacity improvement. Therefore, while hard carbon materials exhibit high rate performance, their low initial coulombic efficiency necessitates manipulation of their structure and pore size to enhance ion diffusion efficiency and reduce irreversible capacity generation. Current research shows that lithium-ion storage in hard carbon primarily occurs through edge and defect adsorption, interlayer intercalation, and pore filling. Thus, the pore structure of hard carbon is crucial.

[0004] Depending on the type of raw materials, hard carbon can be divided into biomass-based hard carbon, pitch-based hard carbon, and resin-based hard carbon. Among them, the molecular structure of resin-based precursors is relatively simple and controllable, and the relevant molecular structure can be designed as needed to precisely construct adjustable pore structures and active sites at the molecular level, resulting in better rate capability and cycle stability of hard carbon materials. However, due to the long resin curing process, pore-forming agents are prone to sedimentation, making it difficult to form uniform and dense pores.

[0005] Therefore, improving the pore size uniformity of hard carbon materials and enhancing their practicality in batteries is an important research direction at present. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a resin-based hard carbon material, its preparation method, and a battery thereof. The resin-based hard carbon provided by the present invention has narrow, uniform, and dense pores, possessing a microporous and abundant ultramicroporous structure, which is beneficial for lithium-ion storage. Furthermore, the ultramicropores isolate the entry of electrolyte, avoiding excessive side reactions and irreversible capacity buildup while achieving lithium-ion storage. It also retains the high-rate performance characteristics of hard carbon materials. The zinc element within the pores has a lithiophilic effect, further attracting lithium ions into the pores. Thus, the resin-based hard carbon material achieves improved capacity and first-time efficiency while maintaining high-rate performance.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a resin-based hard carbon material having a porous structure, the porous structure including micropores and ultramicropores; the pore size distribution of the ultramicropores is <0.7nm, the pore size distribution of the micropores is 0.7-2nm and excluding 2nm; and elemental zinc is also attached to the pore walls of the porous structure.

[0009] For example, the pore size of the ultramicropores can be 0.1nm, 0.15nm, 0.2nm, 0.25nm, 0.3nm, 0.35nm, 0.4nm, 0.45nm, 0.5nm, 0.55nm, 0.6nm, 0.65nm, or 0.69nm, etc.; the pore size of the micropores can be 0.7nm, 0.8nm, 0.9nm, 1nm, 1.1nm, 1.2nm, 1.3nm, 1.4nm, 1.5nm, 1.6nm, 1.7nm, 1.8nm, 1.9nm, or 1.99nm, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0010] It should be noted that the definitions of micropores and ultramicropores in this invention are determined according to the standards of the International Union of Pure and Applied Chemistry (IUPAC).

[0011] It should be noted that the porous structure in this application also has elemental zinc attached to the pore walls, which means that elemental zinc is adhered to the pore walls of the porous carbon. It is possible that the pores of the porous carbon also contain elemental zinc.

[0012] The resin-based hard carbon material provided by this invention has a porous structure with narrow pores containing both micropores and ultramicropores, resulting in a relatively uniform pore size distribution. The micropores and abundant ultramicropores provide channels for lithium-ion diffusion, facilitating lithium-ion storage. The uniform ultramicropores do not contact the electrolyte, and the desolvation of solvated lithium ions occurs around the pores rather than within them. This allows lithium ions to enter and form clusters even without electrolyte, reducing the interfacial resistance between the electrolyte and the electrode, increasing capacity while effectively reducing side reactions and improving first-time efficiency. Simultaneously, the presence of ultramicropores preserves the high-rate performance of the hard carbon material. Furthermore, the zinc within the pores further attracts lithium ions for storage, promoting lithium-ion deposition. Therefore, this invention achieves the goal of improving the capacity and first-time efficiency of the resin-based hard carbon material while maintaining its high-rate performance.

[0013] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0014] Preferably, the pore size distribution of the micropores is 0.7 to 1.5 nm, such as 0.7 nm, 0.75 nm, 0.8 nm, 0.85 nm, 0.9 nm, 0.95 nm, 1 nm, 1.05 nm, 1.1 nm, 1.15 nm, 1.2 nm, 1.25 nm, 1.3 nm, 1.35 nm, 1.4 nm, 1.45 nm, or 1.5 nm, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0015] Preferably, the pore size distribution of the micropores is 0.3 to 0.7 nm, excluding 0.7 nm, such as 0.3 nm, 0.35 nm, 0.4 nm, 0.45 nm, 0.5 nm, 0.55 nm, 0.6 nm, 0.65 nm, or 0.69 nm, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0016] In this invention, the pore size distribution of the ultra-micropores is controlled to 0.3-0.7 nm (excluding 0.7 nm), which will not affect the high rate performance of the hard carbon material, but can improve the lithium-ion battery capacity and first-time efficiency of the anode material.

[0017] Preferably, the porosity of the resin-based hard carbon material is 10% to 90%, such as 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0018] Preferably, the distribution rate of the micropores in the pore structure is 60% to 100%, such as 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0019] In this invention, the distribution rate of ultramicropores refers to the cumulative pore volume ratio of ultramicropores among all pore types. Controlling it within the range of 60% to 90% is more conducive to increasing capacity while reducing the occurrence of side reactions, thereby maintaining high initial efficiency.

[0020] Preferably, the pore volume of the hole structure is 0.05–2 cm. 3 / g, for example 0.05cm 3 / g, 0.1cm 3 / g, 0.2cm 3 / g, 0.3cm 3 / g, 0.4cm 3 / g, 0.5cm 3 / g, 0.6cm 3 / g, 0.7cm 3 / g, 0.8cm 3 / g, 0.9cm 3 / g, 1cm 3 / g, 1.1cm 3 / g, 1.2cm 3 / g, 1.3cm 3 / g, 1.4cm 3 / g, 1.5cm 3 / g, 1.6cm 3 / g, 1.7cm 3 / g, 1.8cm 3 / g, 1.9cm 3 / g or 2cm 3 / g, etc., but not limited to the listed values; other unlisted values ​​within this range also apply.

[0021] Preferably, the zinc content in the resin-based hard carbon material is 3000ppm to 9000ppm, such as 3000ppm, 3500ppm, 4000ppm, 4500ppm, 5000ppm, 5500ppm, 6000ppm, 6500ppm, 7000ppm, 7500ppm, 8000ppm, 8500ppm, or 9000ppm, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0022] In this invention, the zinc content in the resin-based hard carbon material is 3000ppm to 9000ppm, which can achieve uniform distribution of zinc in the pores, thus playing a good lithium affinity role, without affecting the lithium storage effect of the pores.

[0023] Preferably, the resin-based hard carbon material has a spherical or near-spherical morphology.

[0024] Secondly, the present invention provides a method for preparing a resin-based hard carbon material, the method comprising the following steps:

[0025] A mixed solution is obtained by mixing zinc salt, liquid thermosetting resin and solvent. The mixed solution is then spray-dried and cured, followed by carbonization treatment to obtain the resin-based hard carbon material.

[0026] The preparation method provided by this invention involves the interaction of the resin with zinc salt during the polymerization process. Zinc salt acts as a catalyst to promote the condensation and curing of the resin solution, allowing the uniformly mixed solution to rapidly solidify into spheres when spray-dried with hot air. This avoids the sedimentation of the pore-forming agent caused by prolonged curing. The hot air, while evaporating the solvent, also catalyzes the resin curing into spherical particles in one step, resulting in a shorter curing time and a more uniform distribution of zinc salts. Further carbonization treatment causes the zinc salts to pyrolyze and generate gas, which is then reduced to zinc oxide and elemental zinc, reacting with carbon to create pores. Simultaneously, high-temperature evaporation creates pores, adjusting the pore structure of the hard carbon material to include abundant ultrapores and some micropores, with some elemental zinc remaining within the pore structure. Rapid curing reduces the cost of curing, resulting in spherical particles, improving material stability and facilitating production. Furthermore, the raw materials and zinc salts are widely and stably sourced, with high yields and a simple, controllable process, making it suitable for large-scale production and promoting the practical application of porous hard carbon materials.

[0027] In this invention, if conventional heating and stirring curing methods are used, it is difficult to achieve high uniformity and instantaneous curing into spheres in a liquid stirring state. Conventional resin-mixed pore-forming agent methods require long-term liquid static drying and curing after stirring. Zinc chloride will slowly catalyze curing and settle and agglomerate. In the subsequent carbothermic reduction, a large number of micropores and mesopores will be formed at the agglomeration sites, which will seriously affect the first efficiency of lithium batteries. In addition, the use of liquid resin as a carbon source in this process is also a requirement for mixing uniformity. When other powders are used as carbon sources and mixed with zinc salt solutions, they cannot be cured and shaped during the drying process, resulting in poorer uniformity and a greater tendency to form mesopores and macropores.

[0028] Preferably, the mass ratio of the zinc salt to the liquid thermosetting resin is (0.5 to 3):1, for example, 0.5:1, 0.8:1, 1:1, 1.3:1, 1.5:1, 1.8:1, 2:1, 2.3:1, 2.5:1, 2.8:1 or 3:1, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0029] In this invention, by adjusting the mass ratio of the zinc salt to the liquid thermosetting resin to (0.5-3):1, the zinc salt can be pyrolyzed in a smaller and more uniform manner to create pores, thereby obtaining more microporous structures, further reducing the amount of micropores, preventing side reactions caused by excessive amounts, and conversely reducing the initial efficiency of hard carbon.

[0030] Preferably, the mixing includes: adding a saturated zinc salt solution to a liquid thermosetting resin solution to obtain a mixed solution.

[0031] In this invention, the saturated zinc salt solution mixed with the liquid thermosetting resin solution is more conducive to the catalytic curing of the resin by the zinc salt and efficient pore formation; and the saturated solution in this invention refers to the saturation achieved at room temperature (20-30℃).

[0032] Preferably, the liquid thermosetting resin includes one or more of phenolic resin, epoxy resin, and polyimide resin.

[0033] In this invention, liquid thermosetting resin can be used as the preparation raw material, and the provided resin raw material does not contain a curing agent, that is, it is a type of resin that does not require the addition of a specific curing agent to cure. It is not limited to a specific type of resin. Resin types that have the above characteristics and can be carbonized to obtain hard carbon materials are all applicable to this invention. At the same time, there is no special limitation on the specific type of zinc salt. Soluble zinc salt types are all applicable to this invention, such as at least one of zinc nitrate, zinc oxalate, zinc chloride, zinc sulfate, or zinc acetate. In addition, the solvent provided by this invention can dissolve the liquid thermosetting resin. It is not limited to any particular type. It can be adaptively selected and adjusted according to the specific type of resin, such as water or ethanol.

[0034] Preferably, the inlet temperature for spray drying and curing is 300-310℃, such as 300℃, 301℃, 302℃, 303℃, 304℃, 305℃, 306℃, 307℃, 308℃, 309℃ or 310℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0035] Preferably, the outlet temperature of the spray drying curing is 180-200°C, such as 180°C, 185°C, 190°C, 195°C or 200°C, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0036] Preferably, the atmosphere for the carbonization treatment includes a protective atmosphere.

[0037] It should be noted that the protective atmosphere in this invention is a conventional carbonization atmosphere, such as a nitrogen atmosphere and / or an inert gas atmosphere, and the inert gas includes, but is not limited to, argon or helium.

[0038] Preferably, the carbonization temperature is 500 to 900°C, such as 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, or 900°C, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0039] At a carbonization temperature of 500–900°C, zinc salts can better activate carbon, resulting in more microporous structures. Furthermore, under the action of carbothermic reduction, zinc oxide and elemental zinc can be formed, achieving activation and pore formation while leaving a portion of elemental zinc in the pore structure.

[0040] Preferably, the carbonization treatment time is 0.5 to 6 hours, such as 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, or 6 hours, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0041] Preferably, the carbonized product is subjected to acid washing and water washing in sequence.

[0042] As a preferred technical solution, the preparation method includes the following steps:

[0043] A saturated zinc salt solution is added to a liquid thermosetting resin solution to obtain a mixed solution. The mass ratio of zinc salt to liquid thermosetting resin is (0.5-3):1.

[0044] The mixed solution is spray-dried and cured. The inlet temperature of the spray-dried curing process is 300-310℃, and the outlet temperature is 180-200℃.

[0045] The spray-dried and cured material is subjected to carbonization treatment at 500–900°C under a protective atmosphere, followed by acid washing and water washing to obtain the resin-based hard carbon material.

[0046] Furthermore, the preparation method provided in the second aspect of the present invention is used to prepare the resin-based hard carbon material as described in the first aspect.

[0047] Thirdly, the present invention also provides a battery comprising a resin-based hard carbon material as described in the first aspect or a resin-based hard carbon material prepared by the preparation method described in the second aspect.

[0048] The resin-based hard carbon material provided by this invention can be used directly as a negative electrode material in batteries. When used as a negative electrode material, it can be used alone as a negative electrode active material to prepare a negative electrode structure; or it can be combined with other materials (such as silicon-based materials) to jointly prepare a negative electrode structure as a negative electrode active material. Those skilled in the art can make adaptive selections and adjustments according to actual needs.

[0049] Preferably, the battery comprises a lithium-ion battery.

[0050] The resin-based hard carbon material provided by this invention is more suitable for lithium-ion batteries, especially liquid lithium-ion batteries, and can better exert the lithium storage effect of ultra-micropores, thereby improving capacity. However, for sodium and potassium ions, due to their large ionic radius, the improvement of their transport and storage effect in ultra-micropores is limited. However, its application in other types of batteries, such as sodium-ion batteries, potassium-ion batteries, or zinc-ion batteries, is not excluded.

[0051] Furthermore, the liquid lithium-ion battery of the present invention includes a positive electrode, a separator, a negative electrode, and an electrolyte; except for the resin-based hard carbon material provided by the present invention contained in the negative electrode, the other raw materials and preparation processes are all conventional technical solutions, and the present invention applies to corresponding technical solutions that can be reasonably known by those skilled in the art.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] (1) The resin-based hard carbon material provided by the present invention has a porous structure with a relatively narrow pore structure containing both micropores and ultramicropores, and a relatively uniform pore size distribution. The micropores and abundant ultramicropore structure provide channels for lithium-ion diffusion, which is beneficial for lithium-ion storage. The uniform ultramicropores do not come into contact with the electrolyte, and the desolvation of solvated lithium ions occurs around the pore size rather than inside the pores. This allows lithium ions to enter and form clusters without electrolyte, reducing the interfacial resistance between the electrolyte and the electrode, improving capacity while effectively reducing side reactions, and achieving improved first-rate performance. At the same time, the presence of ultramicropores also preserves the high rate performance of the hard carbon material. In addition, the zinc element in the pores further attracts lithium ions to enter the pores for storage, which is beneficial for lithium-ion deposition. Thus, the resin-based hard carbon material achieves the goal of improving the capacity and first-rate performance of the hard carbon material while maintaining high rate performance.

[0054] (2) The preparation method provided by the present invention interacts with zinc salt during the resin polymerization process, which can act as a catalyst to promote the condensation and solidification of the resin solution. This allows the uniformly mixed solution to be quickly solidified into spheres when spray-dried with hot air, avoiding the sedimentation of the pore-forming agent caused by long-term solidification. While evaporating the solvent, the hot air also catalyzes the solidification of the resin into spherical particles in one step. The solidification time is short and the zinc salt is more evenly distributed. Further carbonization treatment causes the zinc salt to pyrolyze and generate gas, which is then reduced to zinc oxide and zinc element reacts with carbon to form pores. At the same time, high-temperature evaporation forms pores, adjusting the pore structure in the hard carbon material to be rich in ultra-micropores and some micropores. Some zinc element remains in the pore structure. Rapid solidification reduces the cost required for solidification, and the formed particles are all spherical, which improves the stability of the material and is beneficial to production. At the same time, the raw materials and zinc salts are widely and stably available, with high yield and simple and controllable process, which is suitable for large-scale production and promotes the practical application of porous hard carbon materials. Attached Figure Description

[0055] Figure 1 This is an adsorption curve of the resin-based hard carbon material provided in Example 1 of the present invention.

[0056] Figure 2 The pore size distribution diagram is shown for the adsorption test of the resin-based hard carbon material provided in Example 1 of the present invention.

[0057] Figure 3 This is an EDS diagram showing the dispersion of elemental zinc in the resin-based hard carbon material provided in Example 1 of the present invention. Detailed Implementation

[0058] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0059] 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 limit this application; the terms “comprising” and “having” and any variations thereof in this application are intended to cover non-exclusive inclusion.

[0060] Example 1

[0061] This embodiment provides a spherical resin-based hard carbon material, which has a porous structure including micropores and ultramicropores; zinc element is also attached to the pore walls of the porous structure.

[0062] The D50, porosity, pore volume, pore size distribution of micropores, pore size distribution of ultramicropores, distribution ratio of ultramicropores in the pores, and mass content of zinc in the resin-based hard carbon material are all shown in Table 1.

[0063] The preparation method of the resin-based hard carbon material is as follows:

[0064] At room temperature (25℃), the first-stage phenolic resin is slowly dissolved in deionized water and stirred until dissolved. At the same time, a certain amount of zinc chloride is dissolved in deionized water to form a saturated solution. The saturated solution is added to the resin solution and stirred thoroughly. The mass ratio of zinc chloride to resin is 1.5:1 to obtain a mixed solution.

[0065] The mixed solution is kept under stirring, and the inlet and outlet of the spray dryer are heated to a specified temperature of 310°C. Then, the mixed solution is continuously passed through the spray dryer by a peristaltic pump for spray drying and solidification. The hot air at the inlet can quickly evaporate the solvent, and the outlet temperature is 200°C, resulting in spherical spray-dried particles.

[0066] The spherical spray dryer was placed in a box furnace, and after fully purging the furnace air with argon gas, it was carbonized at 600°C for 3 hours. The carbonized product was then treated with dilute hydrochloric acid and distilled water in sequence, and dried to obtain the resin-based hard carbon material.

[0067] Example 2

[0068] This embodiment provides a spherical resin-based hard carbon material, which has a porous structure including micropores and ultramicropores; zinc element is also attached to the pore walls of the porous structure.

[0069] The D50, porosity, pore volume, micropore pore size distribution, ultramicropore pore size distribution, and zinc content of the resin-based hard carbon material are shown in Table 1.

[0070] The preparation method of the resin-based hard carbon material is as follows:

[0071] The first-stage phenolic resin was slowly dissolved in deionized water and stirred until dissolved. At the same time, a certain amount of zinc chloride was dissolved in deionized water to form a saturated solution. The saturated solution was added to the resin solution and stirred thoroughly. The mass ratio of zinc chloride to resin was 0.5:1 to obtain a mixed solution.

[0072] The mixed solution is kept under stirring, and the inlet and outlet of the spray dryer are heated to a specified temperature of 300°C. Then, the mixed solution is continuously passed through the spray dryer by a peristaltic pump for spray drying and solidification. The hot air at the inlet can quickly evaporate the solvent, and the outlet temperature is 180°C, resulting in spherical spray-dried particles.

[0073] The spherical spray dryer is placed in a box furnace, and after fully purging the air in the furnace with argon gas, it is carbonized at 500°C. The carbonized product is then treated with dilute hydrochloric acid and distilled water in sequence, and dried to obtain the resin-based hard carbon material.

[0074] Example 3

[0075] This embodiment provides a spherical resin-based hard carbon material, which has a porous structure including micropores and ultramicropores; zinc element is also attached to the pore walls of the porous structure.

[0076] The D50, porosity, pore volume, pore size distribution of micropores, pore size distribution of ultramicropores, distribution ratio of ultramicropores in the pores, and mass content of zinc in the resin-based hard carbon material are all shown in Table 1.

[0077] The preparation method of the resin-based hard carbon material is as follows:

[0078] The first-stage phenolic resin was slowly dissolved in deionized water and stirred until dissolved. At the same time, a certain amount of zinc chloride was dissolved in deionized water to form a saturated solution. The saturated solution was added to the resin solution and stirred thoroughly. The mass ratio of zinc chloride to resin was 3:1 to obtain a mixed solution.

[0079] The mixed solution is kept under stirring, and the inlet and outlet of the spray dryer are heated to a specified temperature of 305°C. Then, the mixed solution is continuously passed through the spray dryer by a peristaltic pump for spray drying and solidification. The hot air at the inlet can quickly evaporate the solvent, and the outlet temperature is 190°C, resulting in spherical spray-dried particles.

[0080] The spherical spray dryer is placed in a box furnace, and after fully purging the air in the furnace with argon gas, it is carbonized at 900°C. The carbonized product is then treated with dilute hydrochloric acid and distilled water in sequence, and dried to obtain the resin-based hard carbon material.

[0081] Example 4

[0082] The difference between this embodiment and Embodiment 1 is that the pore size distribution of the ultramicropores in this embodiment is 0.1 to 0.2 nm.

[0083] In the preparation method, the pore-forming agent was changed to zinc oxalate, and the carbonization temperature was changed to 450℃.

[0084] The remaining preparation methods and parameters are consistent with those in Example 1.

[0085] Example 5

[0086] The difference between this embodiment and Embodiment 1 is that in this embodiment, the distribution rate of micropores in the pore structure is 25%.

[0087] In the preparation method, the inlet and outlet of the spray dryer are heated to a specified temperature of 100℃, and the carbonization temperature is 900℃.

[0088] The remaining preparation methods and parameters are consistent with those in Example 1.

[0089] Example 6

[0090] The difference between this embodiment and Embodiment 1 is that in this embodiment, the distribution rate of micropores in the pore structure is 99%.

[0091] In the preparation method, the mass ratio of zinc chloride to resin is 0.25:1, and the carbonization temperature is 500℃.

[0092] The remaining preparation methods and parameters are consistent with those in Example 1.

[0093] Example 7

[0094] The difference between this embodiment and Example 1 is that in the preparation method of this embodiment, the zinc chloride solution is unsaturated and has a concentration of 200 g / L.

[0095] The remaining preparation methods and parameters are consistent with those in Example 1.

[0096] Example 8

[0097] The difference between this embodiment and Embodiment 1 is that in this embodiment, the mass ratio of zinc chloride to resin is 0.1:1.

[0098] The remaining preparation methods and parameters are consistent with those in Example 1.

[0099] Example 9

[0100] The difference between this embodiment and Embodiment 1 is that the mass ratio of zinc chloride to resin in this embodiment is 4:1.

[0101] The remaining preparation methods and parameters are consistent with those in Example 1.

[0102] Example 10

[0103] The difference between this embodiment and Embodiment 1 is that the carbonization temperature in this embodiment is 450°C.

[0104] The remaining preparation methods and parameters are consistent with those in Example 1.

[0105] Example 11

[0106] The difference between this embodiment and Embodiment 1 is that the carbonization temperature in this embodiment is 950℃.

[0107] The remaining preparation methods and parameters are consistent with those in Example 1.

[0108] Comparative Example 1

[0109] The difference between this comparative example and Example 1 is that in this comparative example, the mixed solution is directly heated and stirred at 100°C to solidify, that is, no spray drying treatment is performed.

[0110] The remaining preparation methods and parameters are consistent with those in Example 1.

[0111] Comparative Example 2

[0112] The difference between this comparative example and Example 1 is that the pore-forming agent in this comparative example is KOH.

[0113] The remaining preparation methods and parameters are consistent with those in Example 1.

[0114] Comparative Example 3

[0115] The difference between this comparative example and Example 1 is that the pore size of the pore structure in this comparative example is greater than 0.7 nm, that is, it does not contain an ultramicroporous structure.

[0116] In the preparation method, the resin is cured and crushed, and then mixed with zinc chloride through solid-phase grinding.

[0117] The remaining preparation methods and parameters are consistent with those in Example 1.

[0118] Table 1 shows the D50, porosity, pore volume, pore size distribution of micropores, pore size distribution of ultramicropores, distribution rate of ultramicropores in pores, and mass content of elemental zinc of the resin-based hard carbon materials provided in Examples 1-11 and Comparative Examples 1-3.

[0119] Test method:

[0120] (a) D50 Test: Particle size was measured using Mastersizer 3000 laser diffraction technology. According to the particle size distribution laser diffraction method GB / T19077-2016, the particle size distribution of the modified graphite material sample was measured. D50: The particle size corresponding to a sample when the cumulative particle size distribution percentage reaches 50%. Its physical meaning is that particles larger than D50 account for 50%, and particles smaller than D50 also account for 50%. D50 is also called the median particle size, and the results are recorded in Table 1.

[0121] (b) Porosity, pore volume and micro / mesopore distribution test: The adsorption and desorption properties of porous carbon materials were tested according to GB / T 19587-2004, and the results are recorded in Table 1.

[0122] (c) Test of the pore size distribution of micropores and the proportion of micropores in the pores: The adsorption and desorption properties of porous carbon materials were tested according to GB / T 19587-2004, and the results are recorded in Table 1.

[0123] (d) Test of zinc content: The zinc content in porous carbon was tested by atomic emission spectrometry using an IPC trace element analyzer, and the results are recorded in Table 1.

[0124] Figure 1 The adsorption curve of the resin-based hard carbon material provided in Example 1 of the present invention is shown.

[0125] Figure 2 The diagram shows the pore size distribution of the resin-based hard carbon material provided in Embodiment 1 of the present invention for adsorption testing.

[0126] from Figure 1 It can be seen that the adsorption isotherm is a type I isotherm, indicating that the porous carbon prepared in the example is microporous porous carbon.

[0127] from Figure 2 It can be seen that the resin-based hard carbon material provided in the embodiments has abundant ultraporous and partially microporous structures.

[0128] Figure 3 The following is an EDS diagram showing the dispersion of elemental zinc in the resin-based hard carbon material provided in Example 1 of the present invention. Figure 3 It can be seen that elemental zinc is uniformly distributed within the pores of the material, which helps to attract lithium metal into the pores for deposition.

[0129] Table 1

[0130]

[0131]

[0132]

[0133] Batteries were prepared using the resin-based hard carbon materials provided in Examples 1-11 and Comparative Examples 1-3, and their performance was tested.

[0134] Battery fabrication:

[0135] The resin-based hard carbon materials provided in Examples 1-11 and Comparative Examples 1-3 were used as negative electrode active materials. The negative electrode active material, the binder polyvinylidene fluoride (PVDF) and the conductive acetylene black were mixed in a mass ratio of 80:5:15. 1-methyl-2-pyrrolidone (NMP) was added and stirred evenly to form a slurry. The slurry was then uniformly coated on the surface of copper foil. The electrode sheet was then dried at 80°C for 12 hours. The electrode sheet was pressed by a roller press and then placed in a vacuum oven to dry at 90°C for 8 hours. The electrode sheet was then slit to form the negative electrode sheet for lithium-ion batteries.

[0136] The prepared negative electrode sheet was assembled into a lithium-ion half-cell, with a lithium metal sheet as the counter electrode; the electrolyte was DEC (diethyl carbonate) + EC (ethylene carbonate) containing 1 mol / L LiPF6 (volume ratio DEC:EC = 7:3), and the separator was made of polypropylene Celgard 2300; the battery assembly was completed in a dry glove box with a relative humidity of less than 1%.

[0137] Performance testing:

[0138] (a) Capacity and First-Time Efficiency: The obtained batteries were subjected to constant-current charge-discharge tests using a Blue Electric testing device at 25±2℃. The discharge cutoff voltage was 0.01V, and the charge cutoff voltage was 2.5V. The first-week charge-discharge test was conducted at a current density of 0.1C, and the corresponding charge specific capacity and first-time coulombic efficiency were recorded. First-time coulombic efficiency = first-time charge capacity / first-time discharge capacity × 100%. The results are recorded in Table 2.

[0139] (b) Rate Performance: The obtained batteries were subjected to rate testing using a Blue Electric testing device at 25±2℃. The rate test conditions were as follows: ① 0.1C discharge to 0.01V, rest for 30 min; 0.1C charge to 2.5V, rest for 30 min; ② 1C discharge to 0.01V, rest for 30 min; 1C charge to 2.5V, rest for 30 min; ③ 2C discharge to 0.01V, rest for 30 min; 2C charge to 2.5V, rest for 30 min; ④ 5C discharge to 0.01V, rest for 30 min; 5C charge to 2.5V, rest for 30 min. This allowed for the testing of fast charging performance (5C / 0.1C). The fast charging performance was calculated as the battery's discharge capacity at 5C current / the battery's discharge capacity at 0.1C current × 100%, and the results are recorded in Table 2.

[0140] The test results are shown in Table 2.

[0141] Table 2

[0142]

[0143]

[0144] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A resin-based hard carbon material, characterized in that, The resin-based hard carbon material has a porous structure, which includes micropores and ultramicropores; the pore size distribution of the ultramicropores is <0.7nm, and the pore size distribution of the micropores is 0.7~2nm, excluding 2nm; zinc element is also attached to the pore walls of the porous structure.

2. The resin-based hard carbon material according to claim 1, characterized in that, The pore size distribution of the micropores is 0.7–1.5 nm; Preferably, the pore size distribution of the ultramicropores is 0.3–0.7 nm, excluding 0.7 nm; Preferably, the porosity of the resin-based hard carbon material is 10-90%; Preferably, the distribution rate of the micropores in the pore structure is 60-90%; Preferably, the pore volume of the hole structure is 0.05–2 cm. 3 / g.

3. The resin-based hard carbon material of claim 1, wherein, The zinc content in the resin-based hard carbon material is 3000ppm to 9000ppm by mass. Preferably, the resin-based hard carbon material has a spherical or near-spherical morphology.

4. A method for producing a resin-based hard carbon material, characterized by comprising: The preparation method includes the following steps: A mixed solution is obtained by mixing zinc salt, liquid thermosetting resin and solvent. The mixed solution is then spray-dried and cured, followed by carbonization treatment to obtain the resin-based hard carbon material.

5. The preparation method according to claim 4, characterized in that, The mass ratio of the zinc salt to the liquid thermosetting resin is (0.5-3):1; Preferably, the mixing includes: adding a saturated zinc salt solution to a liquid thermosetting resin solution to obtain a mixed solution; Preferably, the liquid thermosetting resin includes any one or a combination of at least two of phenolic resin, epoxy resin, or polyimide resin.

6. The preparation method according to claim 4, characterized in that, The inlet temperature of the spray drying curing is 300-310℃, and the outlet temperature of the spray drying curing is 180-200℃.

7. The preparation method according to claim 4, characterized in that, The atmosphere for the carbonization treatment includes a protective atmosphere; Preferably, the carbonization temperature is 500–900°C, and the carbonization time is 0.5–6 hours. Preferably, the carbonized product is subjected to acid washing and water washing in sequence.

8. The preparation method according to claim 4, characterized in that, The preparation method includes the following steps: A saturated zinc salt solution is added to a liquid thermosetting resin solution to obtain a mixed solution. The mass ratio of zinc salt to liquid thermosetting resin is (0.5-3):

1. The mixed solution is spray-dried and cured. The inlet temperature of the spray-dried curing process is 300-310℃, and the outlet temperature is 180-200℃. The spray-dried and cured material is subjected to carbonization treatment at 500–900°C under a protective atmosphere, followed by acid washing and water washing to obtain the resin-based hard carbon material.

9. A battery, characterized by The battery comprises the resin-based hard carbon material as described in any one of claims 1-3 or the resin-based hard carbon material prepared by the preparation method as described in any one of claims 4-8.

10. The battery of claim 9, wherein, The battery includes a lithium-ion battery.

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