Preparation and application of lignin phenolic resin-based carbon negative electrode material capable of storing sodium battery

Abstract

The invention relates to preparation and application of a lignin phenolic resin-based carbon negative electrode material capable of storing a sodium battery. The invention provides a lignin phenolic resin-based carbon negative electrode material of a sodium ion battery, the carbon negative electrode material is lignin formaldehyde resin x / phenol formaldehyde resin y, x and y are integers, and x + y = 10. The invention also provides a preparation method of the lignin phenolic resin-based carbon negative electrode material capable of storing the sodium battery, which comprises the following steps: (a) mixing lignin with phenol, adding a catalyst, and carrying out heat treatment to obtain phenolated lignin; (b) mixing the phenolated lignin in the step (a) with formaldehyde, adding a dispersing agent and a catalyst, and performing heat treatment to obtain a lignin phenolic resin-based material; and (c) transferring the lignin phenolic resin-based material in the step (b) into a tubular furnace for carbonization treatment to obtain the lignin phenolic resin-based carbon negative electrode material. The lignin phenolic resin-based carbon negative electrode material capable of storing the sodium battery, prepared by the invention, has high theoretical specific capacity and excellent cycling stability, and also ensures relatively high first coulombic efficiency.

Description

Technical Field

[0001] This invention belongs to the field of battery materials technology. Specifically, it relates to the preparation of a lignin-phenolic resin-based carbon anode material, which can be used in secondary batteries such as lithium / sodium / potassium ion batteries. Background Technology

[0002] With increasing global concern about climate change and fossil fuel use, researchers are actively developing cost-effective alternative energy technologies, including supercapacitors, fuel cells, and various battery systems. These energy storage technologies not only have enormous development potential but have also begun to demonstrate their application value in multiple fields, such as portable electronic devices, hybrid vehicles, and large-scale industrial energy storage facilities. Lithium-ion batteries, with their high energy storage capacity and excellent electrochemical performance, have become leaders in these applications. However, the limited availability of lithium resources, high mining costs, and uneven distribution pose economic challenges for lithium-ion batteries. Sodium-ion batteries (SIBs) are therefore considered a promising alternative technology. The abundant reserves and low cost of sodium, along with its non-reactive alloying properties with aluminum, make the use of more economical materials possible, further reducing costs. Therefore, sodium-ion batteries, due to their low cost, abundant resources, high efficiency, and fast response time, have become an inevitable trend in the development of energy storage-type ion batteries. Among these anode materials, carbon-based materials are considered the most promising candidates by both academia and industry due to their abundant raw materials, low operating potential, suitable reversible capacity, simple synthesis, and low cost. However, the commercialization of carbon-based materials also places higher demands on other parameters, such as ICE (intercalation potential), pellet density, and tap density. In the field of carbon-containing materials, carbon spheres have great potential in addressing some of the current bottlenecks in SIBs (Single Intake Bodies). Summary of the Invention

[0003] Studies have shown that the charge-discharge curves of hard carbon always exhibit a high-pressure ramp region and a low-pressure plateau region, with the former attributed to the simultaneous and continuous storage of sodium ions at defects, interlayers, and pore surfaces. Subsequently, pore filling occurs in the low-pressure plateau region, with increasing metallization as the pore size increases. Therefore, significant efforts have been made to improve the reversible sodium storage capacity, cycle stability, and rate performance of carbon materials by controlling their morphology, structure, and composition. However, the commercialization of carbon-based materials also places higher demands on other parameters, such as ICE (specific capacity), pellet density, and tap density. In the field of carbon-containing materials, carbon spheres have great potential in addressing some of the current bottlenecks in SIBs (Specific Capacity Intake Blocks). The spherical structure enhances its structural stability, and the spherical structure of carbon spheres increases the tap density of carbon materials, ultimately improving the specific capacity of SIBs.

[0004] To address the limitations of current pure phenolic resin carbon anode materials in terms of specific capacity, rate performance, and overall battery energy density, this invention discloses a lignin-phenolic resin-based carbon anode material capable of storing sodium ions, aiming to improve the specific capacity, rate performance, energy density, and cycle performance of phenolic resin carbon anode materials. The lignin-phenolic resin-based carbon anode provided by this invention is composed of lignin, phenol, and formaldehyde, which can effectively regulate the sodium ion storage mechanism, increase sodium storage capacity, and reduce cost and toxicity. Compared to pure phenolic resin carbon anodes, it has a better pore size distribution, abundant defects, and pore structure. Therefore, during the electrochemical reaction process, it functions as a sodium storage tank, enabling the regulation of sodium ion dynamics and significantly improving the specific capacity, rate performance, and cycle performance of the carbon anode.

[0005] This invention provides a lignin-phenolic resin-based carbon anode material for storing sodium batteries, characterized in that the lignin is phenolized into a portion of the phenolic resin. To this end, this invention provides the following preparation method.

[0006] According to the above-mentioned lignin-phenolic resin-based carbon anode material, alkali lignin, phenol and formaldehyde are mixed in proportion and a suspension polymerization process is adopted to obtain a lignin-phenolic resin precursor, which is then subjected to high-temperature heat treatment to obtain a spherical carbon material.

[0007] According to the above-mentioned lignin-phenolic resin-based carbon anode material, the lignin is cellulose, lignin sulfonate, or alkali lignin; preferably, the lignin is alkali lignin.

[0008] According to the above-mentioned lignin-phenolic resin-based carbon anode material, the phenolic lignin is obtained by adjusting the amount of lignin and phenol, with the lignin to phenol mass ratio being 0:10-10:0, preferably 4:6-6:4, and most preferably 5:5.

[0009] According to the above-mentioned lignin-phenolic resin-based carbon anode material, the molecular weight of polyethylene glycol is 200-20000, preferably 1000-8000, more preferably 1500-6000, and most preferably 6000.

[0010] According to the above-mentioned lignin-phenolic resin-based carbon anode material, the carbonization temperature is 600℃-1500℃, preferably 1100℃-1500℃, and most preferably 1300℃.

[0011] According to the above preparation method, a composite electrode is prepared, which is composed of the above-mentioned lignin phenolic resin-based carbon negative electrode material for storing sodium batteries, a conductive agent, and a binder.

[0012] According to the above preparation method, the present invention also provides a lithium / sodium / potassium ion battery, comprising a positive electrode and a negative electrode, wherein the negative electrode is the composite electrode described in claim 6, and the positive electrode material is sodium cobaltate, sodium nickelate, sodium manganate, sodium chromate, sodium nickel iron manganate, sodium nickel manganate, sodium nickel cobalt manganate, sodium nickel iron manganate titanate, sodium copper iron manganate, sodium iron manganate, or tunnel-type sodium manganate (Na₂O₃). 0.44 One or more of the following: MnO2, sodium vanadium phosphate, and sodium iron phosphate, in any proportion.

[0013] In the above-mentioned composite electrode, the binder is preferably CMC and SBR. They are mixed in a mass ratio of 3:2, and the conductive agent is preferably Super-P. The active negative electrode material accounts for 80-90% by mass, preferably 85%.

[0014] In the aforementioned lithium / sodium / potassium ion batteries, the sodium / potassium ion battery separator is preferably a glass fiber separator, and the lithium ion battery separator is preferably a PP separator. The organic electrolyte is an ether-based electrolyte containing a solute, with a solute concentration of 0.5-3M, preferably 0.5-2M, and most preferably 1M. The ether-based electrolyte includes at least one of ethylene glycol (DEG), dimethyl ether (DME), 1,3-dioxolane (DOL), diethylene glycol dimethyl ether (DIGLYME), and ethylene glycol dimethyl ether (DEGDME), preferably ethylene glycol dimethyl ether (DEGDME) (volume ratio 1:1).

[0015] Compared with the current technology, the advantages and beneficial effects of the present invention are as follows:

[0016] The lignin-phenolic resin-based carbon anode material provided by this invention, capable of storing sodium ions in a battery, exhibits an increased lignin content, leading to changes in defects, total micropore volume, and the number of oxygen-containing functional groups. This allows it to function as a sodium storage tank in electrochemical reactions, providing more active sites for sodium ion adsorption and resulting in stronger adsorption capacity. Furthermore, its abundant pore structure and closed pores not only provide better transport channels for sodium ions but also promote the pore-filling mechanism, conforming to the "adsorption-intercalation-pore-filling" model. This anode material also boasts advantages such as simple preparation process, low cost, high specific capacity, and excellent long-cycle stability, making it a promising novel carbon anode material for industrialization. Attached Figure Description

[0017] Figure 1 This is a comparison chart of the rate performance of sodium-ion batteries in Example 1 and Comparative Example 1;

[0018] Figure 2 This is a comparison chart of the rate performance of sodium-ion batteries in Example 2 and Comparative Example 1;

[0019] Figure 3This is a comparison graph of the rate performance of sodium-ion batteries in Example 3 and Comparative Example 1;

[0020] Figure 4 This is a comparison graph of the cycle performance of sodium-ion batteries in Example 1 and Comparative Example 1;

[0021] Figure 5 This is a comparison graph showing the cycle performance of sodium-ion batteries in Example 2 and Comparative Example 1;

[0022] Figure 6 This is a comparison graph showing the cycle performance of sodium-ion batteries in Example 3 and Comparative Example 1;

[0023] Figure 7 The image shows the SEM image of the carbon anode material in Comparative Example 1.

[0024] Figure 8 The image shows the SEM image of the carbon anode material in Example 1.

[0025] Figure 9 Here is a SEM image of the carbon anode material in Example 2;

[0026] Figure 10 Here is a SEM image of the carbon anode material in Example 3; Detailed Implementation

[0027] In order to solve the technical problems of low specific capacity, poor rate performance, poor long-cycle stability, and low initial coulombic efficiency of current phenolic resin-based carbon anodes, the inventors conducted long-term research and experiments. Finally, they surprisingly discovered that if lignin is added to the precursor synthesis process of existing pure phenolic resin-based carbon anode materials, the above-mentioned problems of current phenolic resin-based carbon anodes can be solved. In particular, when one of cellulose, lignin sulfonate, sodium lignin sulfonate, calcium lignin sulfonate, ammonium lignin sulfonate, or alkali lignin is added during the precursor synthesis process of phenolic resin-based carbon anode materials, the technical problems of low specific capacity, poor rate performance, poor long-cycle stability, and low initial coulombic efficiency are readily solved.

[0028] To better understand the present invention, the present invention will be further described in detail below with reference to specific embodiments, but the implementation methods of the present invention are not limited thereto.

[0029] The instrument models and parameter conditions used in the following examples are as follows:

[0030] SEM: Hitachi S8100 and S4800 cold field scanning electron microscopes were used with an accelerating voltage of 10kV.

[0031] Example 1

[0032] A lignin-phenolic resin-based carbon anode material suitable for storing sodium batteries is composed of lignin, phenol, and formaldehyde, with a mass ratio of lignin, phenol, and formaldehyde of 20:30:50. The lignin and phenol are added to a three-necked flask equipped with a mechanical stirrer and a condenser. Sulfuric acid (7wt%) is then added as a catalyst. The mechanical stirrer is started, and the mixture is heated in an oil bath to 140°C for 2 hours. After cooling to room temperature, a liquefied product, namely phenolic lignin, is obtained.

[0033] The phenolic lignin and formaldehyde were added to a three-necked flask equipped with a mechanical stirrer and a condenser. Polyethylene glycol (2.5 wt%) and ammonia (3.0 wt%) were then added as a dispersant. The mechanical stirrer was started, and the mixture was heated in an oil bath to 85°C for 15 hours. Hexamethylenetetramine (5 wt%) was then added as a curing agent, and the temperature was raised to 95°C for 4 hours. The suspension was centrifuged, the lower layer was collected and filtered, and the product was dried in an 80°C oven for 4 hours to obtain the lignin-phenolic resin-based material (LPF-4).

[0034] LPF-4 was placed in an Al2O3 tube furnace and heated to 1300℃ under a N2 atmosphere at a heating rate of 3℃·min. -1 The carbonization time is 2 hours. After carbonization is completed and the temperature is lowered to room temperature, the lignin phenolic resin-based carbon anode material (LPFC-4) can be obtained.

[0035] The above-mentioned lignin-phenolic resin-based carbon anode material (LPFC-4) was mixed with conductive agent (Super-P) and binder (CMC and SBR) at a mass ratio of 85:10:3:2. Deionized water was used as solvent to obtain electrode slurry. The mixture was stirred until homogeneous and then uniformly coated onto the surface of copper foil using an automatic coating machine. The composite electrode was obtained by vacuum drying at 100°C for 12 hours. The composite electrode was then stamped into 13mm circular electrode sheets for sodium-ion battery testing.

[0036] The half-cell was prepared in an argon-filled glove box. The composite electrode sheet was assembled with sodium metal to form a sodium-ion battery. The sodium-ion battery specification was CR2032, the separator was a glass fiber separator, and the electrolyte was 1M NaPF6 DEGDME electrolyte.

[0037] The sodium-ion battery was subjected to constant current charge-discharge test, with the test system being the Wuhan Bluepoint Battery Test System and the test environment temperature being 25℃.

[0038] Example 2

[0039] A lignin-phenolic resin-based carbon anode material suitable for storing sodium batteries is composed of lignin, phenol, and formaldehyde, with a mass ratio of lignin, phenol, and formaldehyde of 25:25:50. The lignin and phenol are added to a three-necked flask equipped with a mechanical stirrer and a condenser. Sulfuric acid (7 wt%) is then added as a catalyst. The mechanical stirrer is started, and the mixture is heated in an oil bath to 140°C for 2 hours. After cooling to room temperature, a liquefied product, namely phenolic lignin, is obtained.

[0040] The phenolic lignin and formaldehyde were added to a three-necked flask equipped with a mechanical stirrer and a condenser. Polyethylene glycol (2.5 wt%) and ammonia (3.0 wt%) were then added as a dispersant. The mechanical stirrer was started, and the mixture was heated in an oil bath to 85°C for 15 hours. Hexamethylenetetramine (5 wt%) was then added as a curing agent, and the temperature was raised to 95°C for 4 hours. The suspension was centrifuged, the lower layer was collected and filtered, and the product was dried in an 80°C oven for 4 hours to obtain the lignin-phenolic resin-based material (LPF-5).

[0041] LPF-5 was placed in an Al2O3 tube furnace and heated to 1300℃ under a N2 atmosphere at a heating rate of 3℃·min. -1 The carbonization time is 2 hours. After carbonization is completed and the temperature is lowered to room temperature, the lignin phenolic resin-based carbon anode material (LPFC-5) can be obtained.

[0042] The above-mentioned lignin-phenolic resin-based carbon anode material (LPFC-5) was mixed with conductive agent (Super-P) and binder (CMC and SBR) at a mass ratio of 85:10:3:2. Deionized water was used as solvent to obtain electrode slurry. The mixture was stirred until homogeneous and then uniformly coated onto the surface of copper foil using an automatic coating machine. The composite electrode was obtained by vacuum drying at 100°C for 12 hours. The composite electrode was then stamped into 13mm circular electrode sheets for sodium-ion battery testing.

[0043] The half-cell was prepared in an argon-filled glove box. The composite electrode sheet was assembled with sodium metal to form a sodium-ion battery. The sodium-ion battery specification was CR2032, the separator was a glass fiber separator, and the electrolyte was 1M NaPF6 DEGDME electrolyte.

[0044] The sodium-ion battery was subjected to constant current charge-discharge test, with the test system being the Wuhan Bluepoint Battery Test System and the test environment temperature being 25℃.

[0045] Example 3

[0046] A lignin-phenolic resin-based carbon anode material suitable for storing sodium batteries is composed of lignin, phenol, and formaldehyde, with a mass ratio of lignin, phenol, and formaldehyde of 30:20:50. The lignin and phenol are added to a three-necked flask equipped with a mechanical stirrer and a condenser. Sulfuric acid (7 wt%) is then added as a catalyst. The mechanical stirrer is started, and the mixture is heated in an oil bath to 140°C for 2 hours. After cooling to room temperature, a liquefied product, namely phenolic lignin, is obtained.

[0047] The phenolic lignin and formaldehyde were added to a three-necked flask equipped with a mechanical stirrer and a condenser. Polyethylene glycol (2.5 wt%) and ammonia (3.0 wt%) were then added as a dispersant. The mechanical stirrer was started, and the mixture was heated in an oil bath to 85°C for 15 hours. Hexamethylenetetramine (5 wt%) was then added as a curing agent, and the temperature was raised to 95°C for 4 hours. The suspension was centrifuged, the lower layer was collected and filtered, and the product was dried in an 80°C oven for 4 hours to obtain the lignin-phenolic resin-based material (LPF-6).

[0048] LPF-6 was placed in an Al2O3 tube furnace and heated to 1300℃ under a N2 atmosphere at a heating rate of 3℃·min. -1 The carbonization time is 2 hours. After carbonization is completed and the temperature is lowered to room temperature, the lignin phenolic resin-based carbon anode material (LPFC-6) can be obtained.

[0049] The above-mentioned lignin-phenolic resin-based carbon anode material (LPFC-6) was mixed with conductive agent (Super-P) and binder (CMC and SBR) at a mass ratio of 85:10:3:2. Deionized water was used as solvent to obtain electrode slurry. The mixture was stirred until homogeneous and then uniformly coated onto the surface of copper foil using an automatic coating machine. The composite electrode was obtained by vacuum drying at 100°C for 12 hours. The composite electrode was then stamped into 13mm circular electrode sheets for sodium-ion battery testing.

[0050] The half-cell was prepared in an argon-filled glove box. The composite electrode sheet was assembled with sodium metal to form a sodium-ion battery. The sodium-ion battery specification was CR2032, the separator was a glass fiber separator, and the electrolyte was 1M NaPF6 DEGDME electrolyte.

[0051] The sodium-ion battery was subjected to constant current charge-discharge test, with the test system being the Wuhan Bluepoint Battery Test System and the test environment temperature being 25℃.

[0052] Comparative Example 1

[0053] A phenolic resin-based carbon anode material for storing sodium batteries is composed of phenol and formaldehyde, wherein the mass ratio of phenol to formaldehyde is 50:50.

[0054] The phenol and formaldehyde were added to a three-necked flask equipped with a mechanical stirrer and a condenser. Polyethylene glycol (2.5 wt%) and ammonia (3.0 wt%) were then added as a dispersant. The mechanical stirrer was started, and the mixture was heated in an oil bath to 85°C for 15 hours. Hexamethylenetetramine (5 wt%) was then added as a curing agent, and the temperature was raised to 95°C for 4 hours. The suspension was centrifuged, the lower layer was collected and filtered, and the product was dried in an 80°C oven for 4 hours to obtain the phenolic resin-based material (PF).

[0055] PF was placed in an Al2O3 tube furnace and heated to 1300℃ under a N2 atmosphere at a heating rate of 3℃·min. -1 The carbonization time is 2 hours. After carbonization is completed and the temperature is lowered to room temperature, phenolic resin-based carbon anode material (PFC) can be obtained.

[0056] The above-mentioned phenolic resin-based carbon anode material (PFC) was mixed with a conductive agent (Super-P) and binders (CMC and SBR) at a mass ratio of 85:10:3:2. Deionized water was used as a solvent to obtain an electrode slurry. The mixture was stirred until homogeneous and then uniformly coated onto the surface of copper foil using an automatic coating machine. The composite electrode was then vacuum dried at 100°C for 12 hours to obtain a composite electrode. This composite electrode was then stamped into 13mm circular electrode sheets for sodium-ion battery testing.

[0057] The half-cell was prepared in an argon-filled glove box. The composite electrode sheet was assembled with sodium metal to form a sodium-ion battery. The sodium-ion battery specification was CR2032, the separator was a glass fiber separator, and the electrolyte was 1M NaPF6 DEGDME electrolyte.

[0058] The sodium-ion battery was subjected to constant current charge-discharge test, with the test system being the Wuhan Bluepoint Battery Test System and the test environment temperature being 25℃.

[0059] Figure 1 This is a comparison chart of the rate performance of sodium-ion batteries in Example 1 and Comparative Example 1. Figure 1 It can be seen that when the mass ratio of lignin, phenol and formaldehyde is 20:30:50, its rate performance is also slightly improved (15.77% improvement in Example 1). Figure 2 This is a comparison chart of the rate performance of sodium-ion batteries in Example 2 and Comparative Example 1. Figure 2 It can be seen that when the mass ratio of lignin, phenol and formaldehyde is 25:25:50, its rate performance is significantly improved (30.96% improvement in Example 2). Figure 3 This is a comparison chart of the rate performance of sodium-ion batteries in Example 3 and Comparative Example 1. Figure 3It can be seen that when the mass ratio of lignin, phenol and formaldehyde is 30:20:50, its rate performance is not much different from that of Comparative Example 1 (Example 3 shows a 9.27% ​​improvement).

[0060] Figure 4 This is a comparison chart of the cycle performance of sodium-ion batteries in Example 1 and Comparative Example 1. Figure 4 It can be seen that when the mass ratio of lignin, phenol and formaldehyde is 20:30:50, its cycle performance is also slightly improved (20.73% improvement in Example 1). Figure 5 This is a comparison graph showing the cycle performance of sodium-ion batteries in Example 2 and Comparative Example 1. Figure 5 It can be seen that when the mass ratio of lignin, phenol and formaldehyde is 25:25:50, its cycle performance is significantly improved (39.53% improvement in Example 2). Figure 6 This is a comparison graph showing the cycle performance of sodium-ion batteries in Example 3 and Comparative Example 1. Figure 6 It can be seen that when the mass ratio of lignin, phenol and formaldehyde is 30:20:50, its cycle performance is not much different from that of Comparative Example 1 (Example 3 improved by 9.42%).

[0061] Figure 7 The image shows the SEM image of the carbon anode material in Comparative Example 1. Figure 7 It can be seen that when the mass ratio of phenol to formaldehyde is 50:50, the material surface is smooth and presents a predominantly large sphere (30μm) distribution. Figure 8 The image shown is a SEM image of the carbon anode material in Example 1. Figure 8 It can be seen that when the mass ratio of lignin, phenol and formaldehyde is 20:30:50, the material exhibits some granular nodules, with medium-sized spheres (22μm) being the most prevalent. Figure 9 The image shown is a SEM image of the carbon anode material in Example 2. Figure 9 It can be seen that when the mass ratio of lignin, phenol and formaldehyde is 25:25:50, more nodules appear on the surface of the material, which are mostly small spheres (14μm). Figure 10 The image shown is a SEM image of the carbon anode material in Example 3. Figure 10 It can be seen that when the mass ratio of lignin, phenol and formaldehyde is 30:20:50, the surface of the material is relatively rough, and it is mostly distributed with small spheres (10μm).

Claims

1. A method for preparing a lignin-phenolic resin-based carbon anode material for sodium-ion batteries, characterized in that, The carbon anode material is lignin-formaldehyde resin x / phenol-formaldehyde resin y, where x and y are both integers, and x+y=10; the preparation method specifically includes the following steps: (a) A mixture of lignin and phenol was heated and stirred using sulfuric acid as a catalyst to obtain phenolic lignin. (b) The phenolic lignin obtained in step (a) is mixed with formaldehyde, and polyethylene glycol is used as a dispersant and ammonia water is used as a catalyst. The mixture is heated to obtain lignin phenolic resin-based material. (c) The lignin-phenolic resin-based material obtained in step (b) is transferred to a tubular furnace and heated and carbonized under protective gas to obtain a lignin-phenolic resin-based carbon anode material.

2. The preparation method according to claim 1, wherein, Lignin can be cellulose, lignin sulfonate, or alkali lignin; the preferred lignin is alkali lignin.

3. The preparation method according to claim 1 or 2, wherein, Phenolic lignin is prepared by mixing lignin and phenol in a mass ratio of 0:10-10:0, preferably 4:6-6:4, and most preferably 5:

5.

4. The preparation method according to claims 1-3, wherein, The molecular weight of polyethylene glycol is 200-20000, preferably 1000-8000, more preferably 1500-6000, and most preferably 6000.

5. The preparation method according to claims 1-4, wherein, The carbonization temperature is 600℃-1500℃, preferably 1100℃-1500℃, and most preferably 1300℃.

6. A composite electrode, which is prepared by using the lignin-phenolic resin-based carbon negative electrode material according to any one of claims 1-5, a conductive agent, and a binder.

7. A lithium / sodium / potassium ion battery, comprising a positive electrode and a negative electrode, wherein, The negative electrode is the composite electrode described in claim 6, and the positive electrode material is sodium cobaltate, sodium nickelate, sodium manganate, sodium chromate, sodium nickel iron manganate, sodium nickel manganate, sodium nickel cobalt manganate, sodium nickel iron manganate titanate, sodium copper iron manganate, sodium iron manganate, or tunnel-type sodium manganate (Na₂O₃). 0.44 One or more of the following: MnO2, sodium vanadium phosphate, and sodium iron phosphate, in any proportion.

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