Anode material for hybrid supercapacitors using marine biomass and its manufacturing method

Abstract

The present invention provides a method for manufacturing a negative electrode material for a hybrid supercapacitor using marine biomass, comprising the steps of: pre-treating marine biomass to form a precursor in powder form; hydrothermally treating the powder precursor in the presence of a nitrogen-containing compound to form nitrogen-doped hydrothermal carbon; carbonizing the hydrothermal carbon in an inert atmosphere to form porous carbon; and introducing lithium ions into the porous carbon; and a negative electrode material for a hybrid supercapacitor using marine biomass, comprising a porous carbon material derived from marine biomass, wherein the porous carbon material comprises a carbon matrix containing nitrogen heteroatoms; and lithium ions chemically or physically bonded to surface functional groups of the carbon matrix. The present invention has the effect of improving electrolyte wettability due to enhanced compatibility at the electrode-electrolyte interface. In particular, the present invention has the effect of improving ion diffusion and charge transfer rates within the porous carbon structure. Furthermore, the present invention has the effect of increasing specific capacitance and power density, and securing stable electrochemical cycling performance suitable for use in high-power supercapacitors. In addition, the present invention has the effect of utilizing marine biomass as a sustainable and high-value-added resource.

Description

Technology Field

[0001] The present invention relates to a cathode material for a hybrid supercapacitor using marine biomass and a method for manufacturing the same. More specifically, the invention relates to a cathode material for a hybrid supercapacitor using marine biomass and a method for manufacturing the same, which enables the production of a cathode material for a hybrid supercapacitor having high power density and improved interfacial performance through a hydrothermal synthesis method using marine biomass. Background Technology

[0003] In general, supercapacitors are a type of energy storage system capable of storing electrical energy through physical means. Due to their fast charging speeds and high power output density, they are attracting attention in the market for products requiring high power consumption, such as hybrid and electric vehicles.

[0004] In particular, supercapacitors are continuing to grow due to their expanded application in various fields (automotive, renewable energy, smart grids, etc.), and with the increasing demand for future small power devices, their utility is also increasing due to the strengths of energy stability and fire safety, driven by the requirements for high-speed response, miniaturization, and high safety.

[0005] Furthermore, as the eco-friendly energy market expands due to stricter global environmental regulations, the demand for supercapacitors, which are emerging as a key future energy storage device in the renewable energy sector, is increasing every year.

[0006] These supercapacitors are classified into electric double-layer capacitors and pseudocapacitors, and there are also hybrid capacitors, which are asymmetric systems combining electric double-layer capacitors and pseudocapacitors.

[0007] Here, the electric double layer capacitor has a structure in which an electrolyte is filled between two electrodes, and when the two electrodes become oppositely charged due to a potential difference, electrolyte ions separate and adsorb onto the electrode surfaces, thereby electrostatically storing electrical energy.

[0008] Therefore, electric double-layer capacitors use porous materials with a high specific surface area, particularly porous carbon materials, to increase capacitance, as a larger specific surface area of ​​the electrode allows more electrolyte ions to be adsorbed onto the electrode surface.

[0009] However, although the development of Hybrid Super Capacitors (HSCs) with high energy density is underway by adopting the principles of secondary batteries such as lithium-ion batteries, research is being conducted to address the drawbacks of secondary batteries, such as low power density, which still appear in Hybrid Super Capacitors.

[0010] In addition, large seaweeds such as *Seaweed*, *Kelp*, *Sargassum*, and *Ulva* are utilized as marine (seaweed) biomass resources.

[0011] By removing elements other than C and N from C, H, N, O, and S, which are the basic constituent elements of proteins contained in such marine biomass, naturally derived nitrogen-doped porous carbon that does not require nitrogen doping can be obtained.

[0012] However, while marine biomass is utilized in some industrial sectors, it has become difficult to find methods and conduct research for its use as a cathode material for supercapacitors. Prior art literature

[0014] Korean Registered Patent Publication No. 10-1166696 (July 19, 2012) Korean Published Patent Publication No. 10-2013-0014796 (February 12, 2013) Korean Published Patent Publication No. 10-2015-0124716 (November 6, 2015) International Publication WO2016 / 210107 (December 29, 2016) Korean Registered Patent Publication No. 10-1734822 (May 12, 2017) Korean Published Patent Publication No. 10-2019-0046003 (May 7, 2019) Korean Registered Patent Publication No. 10-2021049 (September 11, 2019) Korean Published Patent Publication Korean Published Patent Application No. 10-2022-0049723 (April 22, 2022) Korean Registered Patent Application No. 10-2025-0069024 (May 19, 2025) Korean Registered Patent Application No. 10-2916039 (January 21, 2026) The problem to be solved

[0015] Therefore, the present invention has been devised to solve the aforementioned conventional problems, and

[0016] The present invention aims to provide a cathode material for a hybrid supercapacitor using marine biomass and a method for manufacturing the same, wherein a porous cathode material can be produced by carbonizing and activating marine biomass through a hydrothermal synthesis method. means of solving the problem

[0018] The method for manufacturing a cathode material for a hybrid supercapacitor using marine biomass according to the present invention to achieve the above objective is,

[0019] A step of pre-treating marine biomass to form a precursor in powder form;

[0020] A step of hydrothermally treating the above powder precursor in the presence of a nitrogen-containing compound to form nitrogen-doped hydrothermal carbon;

[0021] A step of forming porous carbon by carbonizing the above hydrothermal carbon in an inert atmosphere; and

[0022] It is characterized by including the step of introducing lithium ions into the porous carbon.

[0023] Here, the above hydrothermal treatment is characterized by being performed at 180 to 230°C for 6 to 12 hours.

[0024] In particular, the above nitrogen-containing compound is characterized by using any one of urea, melamine, ammonium salt, or amino acid-containing compounds.

[0025] In addition, the carbonization is characterized by being performed at 600 to 900°C in a nitrogen or argon atmosphere.

[0026] The method is further characterized by including the step of mixing the nitrogen-doped porous carbon with KOH in a mass ratio of 1:1 to 1:4 and activating it at 700 to 850°C for 1 to 2 hours.

[0027] Meanwhile, the above lithium ion is characterized by using one of LiOH, Li₂CO₃, and LiNO₃.

[0028] At this time, the lithium ions are based on the total weight percentage of porous carbon. It is characterized by using 0.1 to 5 weight percent.

[0029] In addition, the cathode material for a hybrid supercapacitor using marine biomass according to the present invention for achieving the above objective is,

[0030] As a porous carbon material derived from marine biomass,

[0031] It is characterized by comprising: a carbon matrix containing nitrogen heteroatoms; and lithium ions chemically or physically bonded to surface functional groups of the carbon matrix.

[0032] Here, the above nitrogen heteroatom is characterized by using one of pyridine nitrogen, pyrrole nitrogen, or graphite nitrogen. Effects of the invention

[0034] The present invention has the effect of improving electrolyte wettability due to improved compatibility at the electrode-electrolyte interface.

[0035] In particular, the present invention has the effect of improving ion diffusion and charge transfer rates within a porous carbon structure.

[0036] In addition, the present invention has the effect of increasing specific capacitance and power density, and securing stable electrochemical cycling performance suitable for use in high-power supercapacitors.

[0037] In addition, the present invention has the effect of utilizing marine biomass as a sustainable and high-value-added resource. Specific details for implementing the invention

[0039] The cathode material for a hybrid supercapacitor using marine biomass and the method for manufacturing the same according to the present invention, for achieving the above-mentioned purpose, are described step-by-step as follows.

[0040] The present invention

[0041] A step of pre-treating marine biomass to form a precursor in powder form;

[0042] A step of hydrothermally treating the above powder precursor in the presence of a nitrogen-containing compound to form nitrogen-doped hydrothermal carbon;

[0043] A step of forming porous carbon by carbonizing the above hydrothermal carbon in an inert atmosphere; and

[0044] It includes the step of introducing lithium ions into the porous carbon.

[0045] The raw materials used in the present invention are,

[0046] Marine biomass (carbon precursor);

[0047] Nitrogen-containing compound (using any one of urea, melamine, ammonium salt, or amino acid-containing compound);

[0048] Lithium ion source (using any one of LiOH, Li₂CO₃, and LiNO₃);

[0049] Activator (use any one of KOH, ZnCl₂, or H₃PO₄);

[0050] Solvent (deionized water);

[0051] <Stage 1: Hybrid Hydrothermal Carbonization Using Nitrogen Doping>

[0052] First, the marine biomass is washed and dried, then ground into a fine powder of 100 μm or less.

[0053] The pulverized powder precursor and deionized water are mixed in a mass ratio of 1:3 to 1:6 to form a slurry.

[0054] Here, 5 to 30 weight percent of a nitrogen-containing compound (such as urea) is added relative to the weight of the marine biomass.

[0055] In particular, the above mixture is hydrothermally treated in an autoclave at a temperature of 180 to 230°C and a pressure of 2 to 6 MPa for 6 to 12 hours.

[0056] During this process, the organic structure of the biomass collapses and partial carbonization proceeds, while indirect thermal doping occurs as nitrogen atoms derived from nitrogen compounds penetrate into the carbon matrix.

[0057] This is a key process that determines the electrical conductivity and electrolyte affinity of the final material.

[0058] <Stage 2: Carbonization and Pore Formation>

[0059] The product treated with hydrothermal heat in the first step above is separated and dried, then introduced into a kiln under a nitrogen or argon atmosphere.

[0060] 2 to 5℃ / min -1 It is heated to 600 to 900°C at a slow heating rate and carbonized for 1 to 3 hours.

[0061] At this stage, volatile components are removed and the carbon skeleton is stabilized, while the nitrogen components introduced during the hydrothermal stage are fixed as chemically stable pyridine-type, pyrrole-type, or graphite-type nitrogen to form a porous carbon structure.

[0062] <Step 3: Chemical Activation>

[0063] In order to maximize the specific surface area of ​​the carbonized sample in the second step above, it is mixed with an activator such as KOH in a mass ratio of 1:1 to 1:4.

[0064] This is heated in an inert atmosphere at 700 to 850°C for 1 to 2 hours.

[0065] During this activation process, micropores and mesopores develop on the carbon surface, and after the reaction, the residual potassium component is completely removed by washing with a 1M HCl solution and deionized water to obtain a high-purity porous carbon material.

[0066] <Phase 4: Lithium Ion Introduction>

[0067] Wet impregnation is performed by immersing the porous carbon material activated in the third step above in an aqueous solution of a lithium ion source (LiOH, etc.) with a concentration of 0.05 to 1.0 M.

[0068] At this time, the amount of lithium loaded is adjusted to be 0.1 to 5.0 weight percent relative to the total weight of the carbon material.

[0069] Afterward, it is dried at 80 to 120°C and then subjected to a final heat treatment at 300 to 500°C in an inert atmosphere.

[0070] In this process, instead of being inserted into the carbon lattice, lithium ions are chemically / physically bonded to nitrogen-doped sites and oxygen functional groups on the surface, improving lithium ion affinity during hybrid supercapacitor operation.

[0071] In order to compare the physical properties and confirm the electrochemical performance of the cathode material for a hybrid supercapacitor using marine biomass according to the present invention, tests were conducted through the following examples and comparative examples.

[0072] Ingredients: Seaweed or kelp powder

[0073] Process: Addition of 20 wt% urea (nitrogen source), hydrothermal treatment at 200℃ / 4MPa for 8 hours,

[0074] After carbonization at 800℃, activate with KOH in a 1:3 ratio at 800℃ for 1 hour,

[0075] Heat treatment at 400°C after introducing 2.0 wt% lithium using a 0.5M LiOH solution.

[0076] <Comparative Example 1> Nitrogen-free and lithium-free

[0077] The same seaweed or kelp powder as in Example 1 was used, but without adding urea during hydrothermal treatment and by omitting the lithium ion introduction process.

[0078] <Comparative Example 2> No lithium introduced after nitrogen doping

[0079] Nitrogen doping and activation were performed in the same manner as in Example 1, but the final lithium ion introduction process (Step 4) was omitted.

[0080] <Comparative Example 3> Simple Lithium Mixture (Heat Treatment Omitted)

[0081] Manufactured in the same manner as Example 1, but with the final heat treatment at 400°C after lithium impregnation omitted and only simple drying performed.

[0082]

[0083] The results of the comparison of physical properties through surface area analysis (BET), elemental analysis (EA), and pore structure analysis for Example 1 and Comparative Examples 1, 2, and 3 are shown in Table 1 above. Example 1 secured the highest specific surface area through the addition of a nitrogen-containing compound (urea) and KOH activation during hydrothermal treatment, and showed that lithium ions were stably fixed to the carbon surface through final heat treatment (300 to 500°C). On the other hand, Comparative Example 3 omitted heat treatment, resulting in lithium loss during the washing process and a low content.

[0084]

[0085] The results of the electrochemical performance evaluation for Example 1 and Comparative Examples 1, 2, and 3 are shown in Table 2 above, and Example 1 shows a capacity increase of about 45% or more compared to Comparative Example 2 (lithium not introduced).

[0086] This confirms that lithium ions coupled with nitrogen-doped sites provide additional pseudocapacity while simultaneously improving the wettability of the carbon surface.

[0087] Here, Comparative Example 3 has a high initial capacity, but as the cycle is repeated, lithium ions leach into the electrolyte, causing the lifespan to rapidly decrease, whereas Example 1 showed a high retention rate of over 97% thanks to the strong chemical bond formed by heat treatment at 500°C.

[0088] Therefore, by sequentially applying nitrogen doping and lithium ion introduction to carbon derived from marine biomass, the embodiment of the present invention can overcome the low capacity limitation of conventional activated carbon anodes and simultaneously secure high capacity at the level of lithium-ion batteries and high power characteristics of supercapacitors.

[0089] Although the embodiments of the present invention have been described in detail as above, the scope of the present invention is not limited thereto, and it is obvious that configurations within a scope substantially equivalent to the embodiments of the present invention are included within the scope of the present invention.

Claims

Claim 1 A step of pre-treating marine biomass to form a precursor in powder form; a step of hydrothermally treating the powder precursor in the presence of a nitrogen-containing compound to form nitrogen-doped hydrothermal carbon; and a step of carbonizing the hydrothermal carbon in an inert atmosphere to form porous carbon. and a step of introducing lithium ions into the porous carbon; wherein the hydrothermal treatment comprises washing and drying the marine biomass, grinding it into a fine powder of 100 μm or less, mixing the ground powder precursor with deionized water in a mass ratio of 1:3 to 1:6 to form a slurry, adding 5 to 30 weight% of a nitrogen-containing compound relative to the weight of the marine biomass, and performing the treatment for 6 to 12 hours in a high-pressure steam sterilizer at a temperature of 180 to 230°C and a pressure of 2 to 6 MPa, wherein the nitrogen-containing compound uses any one of urea, melamine, ammonium salt, or an amino acid-containing compound, and the carbonization comprises separating and drying the hydrothermally treated product, then introducing it into a calcination furnace under a nitrogen or argon atmosphere at 2 to 5°C / min -1 The method further comprises the step of heating to 600 to 900°C at a heating rate for 1 to 3 hours, mixing the nitrogen-doped porous carbon with KOH in a mass ratio of 1:1 to 1:4, and activating at 700 to 850°C for 1 to 2 hours, wherein the lithium ion is one of LiOH, Li₂CO₃, and LiNO₃, and the lithium ion is based on the total weight% of the porous carbon A method for manufacturing a negative electrode material for a hybrid supercapacitor using marine biomass, characterized by controlling to support 0.1 to 5 weight% of lithium, drying at 80 to 120°C, and finally heat treating at 300 to 500°C in an inert atmosphere. Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 delete Claim 6 delete Claim 7 delete Claim 8 A porous carbon material derived from marine biomass, manufactured by the method for manufacturing a cathode material for a hybrid supercapacitor using marine biomass according to claim 1, characterized by comprising: a carbon matrix containing nitrogen heteroatoms; and lithium ions chemically or physically bonded to surface functional groups of the carbon matrix. Claim 9 A cathode material for a hybrid supercapacitor using marine biomass according to claim 8, characterized in that the nitrogen heteroatom uses one of pyridine nitrogen, pyrrole nitrogen, or graphite nitrogen.

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