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KR-102962924-B1 - Process for manufacturing highly activated, monolithic mesh-shaped biochar electrodes

KR102962924B1KR 102962924 B1KR102962924 B1KR 102962924B1KR-102962924-B1

Abstract

A method for manufacturing a highly active, highly porous, and highly electrically conductive mesh-shaped monolithic electrode for use in electric energy storage devices including ultracapacitors, pseudocapacitors, and batteries, or in electric power generation devices such as fuel cells, or in gas generation devices such as hydrogen generators or oxygen generators.

Inventors

  • 파비타, 디노
  • 첸, 타오
  • 분, 에릭 피.

Assignees

  • 컨트롤에이매틱스 코포레이션

Dates

Publication Date
20260512
Application Date
20200330
Priority Date
20190329

Claims (20)

  1. A method for producing an electrode used in an ultracapacitor, a pseudo-capacitor, a battery, or a fuel cell, a. (i) a step of formulating a biomass blend having biomass of different particle sizes; (ii) a step of wetting the biomass blend in an aqueous precursor solution other than a binder or adhesive, wherein the aqueous precursor solution softens the surface of lignin, hemicellulose, and cellulose associated with the biomass blend, and the wetted biomass blend has a density of 0.5 g/ cm³ to 4 g/ cm³ ; (iii) a step of casting or molding the biomass blend in a press plate mold in an oven press in the presence of a self-coupled precursor compound and in the absence of a binder material to form a pre-net-shaped biomass wafer, wherein a portion of the biomass blend is deformed during casting or molding by the presence of the self-coupled precursor compound or is re-bonded to another portion of the biomass blend, and (iv) a step of forming one or more biochar electrodes by carbonizing the pre-net-shaped biomass wafer in a furnace to form a net-shaped biochar electrode; and b. A method comprising the step of combining the above-described mesh-shaped biochar electrode with one or more charge collectors, separators, and one or more electrolytes.
  2. A method according to claim 1, wherein, prior to the wetting step, the biomass blend is mechanically converted to a size range of 20 microns to 2 millimeters at its longest dimension through milling, hammer milling, grinding or cutting or alternative milling/grinding operations.
  3. A method according to claim 1, wherein the self-coupled precursor compound comprises an acid, a basic salt, a neutral salt, or a solvent.
  4. A method according to claim 3, wherein the self-bonding precursor compound comprises an acid selected from the group consisting of formic acid, performic acid, acetic acid, peracetic acid, boric acid, nitric acid, or any blend thereof, or hydrogen peroxide.
  5. A method according to paragraph 3, wherein the self-coupled precursor compound comprises a basic salt selected from the group consisting of potassium hydroxide, sodium hydroxide and other metal salts or any blend thereof.
  6. A method according to claim 3, wherein the self-coupled precursor compound comprises a solvent which is water or an organic solvent, and the organic solvent is selected from the group consisting of ethanol, toluene, dimethyl-formamide, or any blend thereof.
  7. A method according to claim 3, wherein the self-coupled precursor compound is applied to the biomass blend at a level of 5 to 91 wt% with respect to the mass of the biomass blend.
  8. In claim 1, the casting or molding of the biomass blend is performed at an elevated temperature according to the following conditions: a. Temperature range of 80°C to 250°C.
  9. A method according to claim 1, further comprising the step of applying a mold release compound for coating the press plate mold associated with the oven press.
  10. In claim 9, the method wherein the mold isoform compound is an organic compound compatible with the biomass blend.
  11. In claim 10, the mold release compound is applied by wetting and coating or by spraying application.
  12. A method according to claim 1, wherein the carbonization occurs in a purged furnace to convert the pre-net-shaped biomass wafer into the net-shaped biochar electrode.
  13. A method according to claim 12, wherein the carbonization temperature is in the range of 700°C to 1100°C and is achieved at a ramp rate of 5 to 20°C/min.
  14. A method according to claim 1, wherein a holder made of ceramic or metal holds the pre-net-shaped biomass wafer during carbonization.
  15. A method according to claim 14, wherein a screen mesh is inserted between the interface between the holders and the pre-mesh-shaped biomass wafer so that gas is discharged from the pre-mesh-shaped biomass wafer while inside the furnace.
  16. A method according to claim 15, further comprising the step of introducing an activating gas into the furnace, wherein the screen mesh allows the activating gas to penetrate the entire surface of at least one of the pre-mesh-shaped biomass wafer and the mesh-shaped biochar electrode.
  17. A method according to claim 1, wherein an inert purge gas is introduced into the furnace at a flow rate of 0.01 to 0.2 ft³ /hour/gram biomass blend while the furnace is at an elevated carbonization temperature.
  18. A method according to claim 1, wherein an activating gas is introduced into the furnace or from a separate furnace during or after carbonization to further activate the mesh-shaped biochar electrode.
  19. A method according to claim 18, wherein the activation gas is superheated steam or carbon dioxide and is introduced into the furnace at a spatial flow rate of 0.001 to 0.1 ft³ /hour/gram biomass blend.
  20. A method according to claim 1, wherein the net-shaped biochar electrode is removed from the furnace and ultrasonically treated in a liquid solvent to remove loose particles.

Description

Process for manufacturing highly activated, monolithic mesh-shaped biochar electrodes 1. Cross-reference to related applications This application claims priority to the provisional application titled “Process for producing highly activated, monolithic mesh-shaped biomass electrodes for use in ultracapacitors, pseudocapacitors, batteries or fuel cells,” filed on March 29, 2019, and assigned serial number 62/826,005. The entire contents of the aforementioned provisional application are incorporated herein by reference. 2. Field of Invention The present disclosure relates to the manufacture of electrodes for electrical storage devices and electrical production devices, and to methods for producing hydrogen gas and oxygen gas, the methods comprising the steps of: formulating a favorable synthetic biomass blend; impregnating the biomass with a pre-activator and/or precursor; casting or molding the impregnated biomass blend to form a pre-net-shaped monolithic biomass wafer or pellet (hereinafter simply referred to as "wafer"); and carbonizing the wafer in a furnace to produce a net-shaped electrically conductive monolithic carbonaceous biochar electrode having hierarchical pores and channels. The present disclosure also relates to the use of monolithic electrodes produced according to the disclosed method in ultracapacitors, pseudocapacitors, batteries and fuel cells, and electrolysis-based gas generators. The processing of "uncarbonized" biomass into a precursor wafer and the pre-net formation do not use a binder. The pre-net-shaped monolithic wafer is subsequently carbonized at high temperature to reduce its size and produce a monolithic net-shaped high-surface-area active biochar carbon electrode containing hierarchical channels and pores. The fabrication of biomass-source carbonaceous monolithic electrodes does not use binders. These mesh-shaped biochar monolithic electrodes can be further shaped and activated before final assembly into ultracapacitors, pseudocapacitors, batteries, or fuel cells, and are used as electrodes for electrolysis-based gas generators to produce hydrogen or oxygen. As global energy consumption and demand increase, there is a growing demand for renewable, sustainable, and clean energy sources, as well as for new, diverse, and scalable energy storage systems. Particularly regarding electrical storage, batteries have been the focus due to their high energy density. However, ultracapacitors and pseudocapacitors have emerged as promising electrochemical energy storage devices due to their high power density, low cost, excellent charge/discharge performance, long cycle life, and environmental benefits. Fuel cells do not store electricity; instead, they provide an energy-efficient method of directly converting chemically stored energy found in hydrogen and hydrocarbon fuels into electricity both on and within the electrodes. Using fuel cells to generate electricity contrasts with conventional power plants, which use combustion fuels to generate steam for subsequent turbine power. In general, batteries are widely used in many applications in daily life. However, batteries have many limitations that restrict their widespread application as sustainable energy storage devices. For example, the extensive use of batteries in cellular devices or automobiles requires massive amounts of lithium, nickel, manganese, and cobalt; since each of these must be harvested from the Earth, the reserves of these natural metals are being depleted. Sustainability is highly limited because these materials are not renewable after extraction. As the demand for these non-renewable metals increases, their prices also rise. While there has been some success in recycling these specific lithium battery-related materials from used batteries, costs and repurification presents many challenges. As disclosed herein, unlike their battery counterparts, ultracapacitors and pseudocapacitors can be manufactured with electrodes made from renewable resources, such as biomass materials (such as wood, grass, and other botanical plants), which can be made less expensive and more environmentally friendly than conventional alkaline or lithium-ion batteries. Additionally, ultracapacitors can charge and discharge at much faster rates and have longer life cycles with minimal performance degradation compared to batteries, due to the fact that energy is stored electrostatically in ultracapacitors and pseudocapacitors rather than chemically as in battery technology. With fast charge-discharge and longer life cycles, ultracapacitors operate better and last longer, providing utility in other applications that require these capabilities. A major disadvantage of typical ultracapacitors is their much lower energy density compared to batteries, which is generally less than 20:1 for ultracapacitors versus lithium-ion batteries. Pseudocapacitors can be simply described as a hybridization of ultracapacitors and batteries. As mentioned above, ultracapac