CN109437902A - The method for preparing porous electrode material - Google Patents

The method for preparing porous electrode material Download PDF

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Publication number
CN109437902A
CN109437902A CN201811562386.XA CN201811562386A CN109437902A CN 109437902 A CN109437902 A CN 109437902A CN 201811562386 A CN201811562386 A CN 201811562386A CN 109437902 A CN109437902 A CN 109437902A
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China
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temperature
electrode material
pore creating
microcrystalline cellulose
sintering
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CN201811562386.XA
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Chinese (zh)
Inventor
李宝光
张恒
刘良禄
谢偲偲
吴笑婕
李海滨
张诚然
白露
许永姿
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Yunnan University YNU
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Yunnan University YNU
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    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/50—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on rare-earth compounds
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
    • C04B35/63—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B using additives specially adapted for forming the products, e.g.. binder binders
    • C04B35/632—Organic additives
    • C04B35/636—Polysaccharides or derivatives thereof
    • C04B35/6365—Cellulose or derivatives thereof
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/64—Burning or sintering processes
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
    • C04B38/06—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by burning-out added substances by burning natural expanding materials or by sublimating or melting out added substances
    • C04B38/063—Preparing or treating the raw materials individually or as batches
    • C04B38/0635—Compounding ingredients
    • C04B38/0645—Burnable, meltable, sublimable materials
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/327—Iron group oxides, their mixed metal oxides, or oxide-forming salts thereof
    • C04B2235/3279—Nickel oxides, nickalates, or oxide-forming salts thereof
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/96—Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/96—Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
    • C04B2235/9607—Thermal properties, e.g. thermal expansion coefficient

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Inert Electrodes (AREA)

Abstract

The invention discloses a kind of methods for preparing porous electrode material, it specifically includes and mixes electrode powder with pore creating material microcrystalline cellulose, after molding, sintering temperature appropriate is warming up to 2 to 5 degrees Celsius of the rate of heating up per minute to be sintered, pore creating material is by burn off in temperature-rise period, temperature-rise period keeps constant rate, without at a slow speed or the degumming stage of constant temperature, stomata is left in electrode material after sintering, wherein range of the mass ratio of electrode powder and microcrystalline cellulose in 100:15 to 100:25.Method of the invention does not need to set the special degumming stage, improves production efficiency.

Description

The method for preparing porous electrode material
Technical field
The present invention relates to a kind of method for preparing porous electrode material, specifically include electrode powder and pore creating material crystallite is fine Dimension element mixing, after molding, is warming up to sintering temperature appropriate and is sintered, pore creating material is being sintered by burn off in temperature-rise period Stomata is left in electrode material afterwards.
Background technique
Porous electrode is the critical function component of various electrochemical devices.In solid oxide fuel cell, generally with Porous ceramics is its electrod assembly.To obtain porous ceramic structure, commonly a kind of method is to make ceramic powder with appropriate Hole agent mixing, after molding, heating sintering, at a high temperature of certain, pore creating material decomposes or burning, generates gas removal, is being sintered Ceramic body in leave corresponding hole, obtain porous ceramics.
Pore creating material decomposes or the process of combustion gas is referred to as scouring processes, this has bulk gas by forming in the process Ceramic body to outside drain.If scouring processes excessively quickly or acutely, react generation gas can not be successfully from It is excluded in the powder micro gap of type, will lead to pressure raising, ceramic body is cracked, to destroy the structure of sintered body. Therefore, generally during preparing porous ceramics using pore creating material, have one it is special at a slow speed or long-time constant temperature it is de- The glue stage.Such as " addition PMMA pore creating material prepares the method (application number of O-Sialon porous ceramics in Chinese granted patent 201310664869.1) it in ", illustrates to need to keep the temperature 1 to 2 hours at a temperature of degumming.
The prolonged degumming stage causes production efficiency to reduce in porous ceramics preparation process, and energy consumption increases, but mesh Before be still the ceramic material usage of trade use method, preparation be used for solid oxide fuel cell porous ceramic electrode When, if having used pore creating material pore-creating, it all joined the special degumming stage.
Summary of the invention
The technical issues of present invention is directed to is taken off slowly, for a long time when preparing porous ceramic electrode using pore creating material The problem of glue process causes efficiency to reduce, and energy consumption increases.
To solve this problem, the present invention proposes to form after mixing it with electrode powder using microcrystalline cellulose as pore creating material, It is sintered with constant heating rate, is automatically performed scouring processes in the process, do not need that the special degumming stage is arranged. Above-mentioned constant heating rate can be set in 2 degrees Celsius/min to 5 degrees Celsius/min range.
Beneficial effect and principle to illustrate the invention do following comparison by this method and using the method for other pore creating materials It discusses.
To prepare Ce0.8Sm0.2O1.9For/NiO porous anode material, can use widely used starch and graphite for Pore creating material.Fig. 1 show the Ce for being added to the starch of 25% mass fraction0.8Sm0.2O1.9The sintering shrinkage of/NiO anode material is bent Line, heating rate are 5 degrees Celsius/min, it is seen that in the degumming stage of 300 degrees centigrades, apparent wave occurs in shrinkage curve It is dynamic, there is an apparent expansion peak, when decomposing degumming corresponding to starch, a large amount of gas causes sample to expand, and correspondingly makes There is obvious crackle in sample structure.Fig. 2 show the Ce for being added to the graphite of 25% mass fraction0.8Sm0.2O1.9/ NiO anode material The sintering shrinkage curve of material, heating rate are 5 degrees Celsius/min, it is seen that in the degumming stage of 600 degrees centigrades, shrinkage curve Also there is apparent fluctuation, reflect when graphite decomposes degumming, sample size with temperature, which rises, quickly turnover occurs, causes to answer Power generates, and sample cracks, and as a result the mechanical integrity of sintered body is destroyed.Above-mentioned two example explanation is made for being added to The ceramic electrode material of hole agent, if in the degumming stage not using slowly heating or prolonged heat preservation, it will be to sample band Carry out the destruction of structural behaviour, this is also exactly the reason of all using the special degumming stage in currently available technology.
Fig. 3 show the microcrystalline cellulose for being added to 25% mass fraction prepared with the inventive method Ce0.8Sm0.2O1.9The sintering shrinkage curve of/NiO anode material, heating rate are 5 degrees Celsius/min, it is seen that on 350 degrees Celsius of left sides Right microcrystalline cellulose degumming stage, sample shrinkage curve maintain smooth state, apparent size mutation do not occur, burn Sample after knot maintains good structural behaviour, does not crack.Fig. 4 show the crystallite for being added to 25% mass fraction The Ce of cellulose0.8Sm0.2O1.9The sintered body microphoto of/NiO anode material, display wherein have good connected pore channel.This The result shows that can be resistant to the heating rate of 5 degrees Celsius/min using microcrystalline cellulose as pore creating material, be done directly in heating Scouring processes do not need that the special degumming stage is arranged, greatly improve production efficiency.
Microcrystalline cellulose pore creating material can be resistant to the reason of quick scouring processes are caused damage without the structure to sample It is analyzed as follows, because it is strip structure, the connectivity of pore-creating is better than other graininess pore creating materials, and the gas that degumming generates is more It is easy to be smoothly discharged；In addition its decomposable process relative starch and graphite etc. more mitigate, can be within the scope of certain temperature It constantly decomposes, will not concentrate and decompose in a narrow temperature range as graphite as starch, thus when reducing degumming The difficulty that gas excludes.The present invention overcomes the technology prejudice for needing to be arranged the special degumming stage when using pore creating material, mention It has supplied using microcrystalline cellulose as pore creating material, to be up to the method that 5 degrees Celsius of heating rate per minute prepares porous electrode material, Improve production efficiency.
Detailed description of the invention
The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
Fig. 1 is the Ce for being added to the starch of 25% mass fraction0.8Sm0.2O1.9The sintering shrinkage curve of/NiO anode material.
Fig. 2 is the Ce for being added to the graphite of 25% mass fraction0.8Sm0.2O1.9The sintering shrinkage curve of/NiO anode material.
Fig. 3 is the Ce for being added to the microcrystalline cellulose of 25% mass fraction0.8Sm0.2O1.9The sintering shrinkage of/NiO anode material Curve.
Fig. 4 is the Ce for being added to the microcrystalline cellulose of 25% mass fraction0.8Sm0.2O1.9The sintered body of/NiO anode material is aobvious Micro- photo.
Specific embodiment
The present invention is described in detail in embodiment described below.
Embodiment 1
Take 100gCe0.8Sm0.2O1.9/ NiO anode powder, mixes with 15g microcrystalline cellulose, and ball milling mixing 1 is small in the ball mill When, take out mixed powder；Mixed powder is dry-pressing formed in a mold, obtains anode green bodies；Anode green bodies are in air atmosphere with 2 Degree Celsius heating rate constant heating rates sintering to 1300 degrees Celsius be sintered 2 hours, obtain Ce0.8Sm0.2O1.9/ NiO porous anode.It receives Shrinkage 13.8%.Porosity is 45%.
Embodiment 2
Take 100gCe0.8Sm0.2O1.9/ NiO anode powder, mixes with 25g microcrystalline cellulose, and ball milling mixing 1 is small in the ball mill When, take out mixed powder；Mixed powder is dry-pressing formed in a mold, obtains anode green bodies；Anode green bodies are in air atmosphere with 5 Degree Celsius heating rate constant heating rates sintering to 1300 degrees Celsius be sintered 2 hours, obtain Ce0.8Sm0.2O1.9/ NiO porous anode.It receives Shrinkage 14.0%.Porosity is 60%.
The above embodiments are merely illustrative of the technical solutions of the present invention, rather than is limited；Although referring to aforementioned reality Applying example, invention is explained in detail, for those of ordinary skill in the art, still can be to aforementioned implementation Technical solution documented by example is modified or equivalent replacement of some of the technical features；And these are modified or replace It changes, the spirit and scope for claimed technical solution of the invention that it does not separate the essence of the corresponding technical solution.

Claims (3)

1. a kind of method for preparing porous electrode material specifically includes and mixes electrode powder with pore creating material microcrystalline cellulose, at It after type, is warming up to sintering temperature appropriate and is sintered, pore creating material is by burn off in temperature-rise period, electrode material after sintering In leave stomata, which is characterized in that temperature-rise period keeps constant rate, without at a slow speed or the degumming stage of constant temperature.
2. the method for preparing porous electrode material as described in claim 1, which is characterized in that heating rate is controlled per minute The range of 2 to 5 degrees Celsius of heating.
3. the method for preparing porous electrode material as described in claim 1, which is characterized in that electrode powder and microcrystalline cellulose Mass ratio 100:15 to 100:25 range.
CN201811562386.XA 2018-12-20 2018-12-20 The method for preparing porous electrode material Pending CN109437902A (en)

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Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3856708A (en) * 1972-04-10 1974-12-24 Reynolds Metals Co Alumina catalyst support
US4119474A (en) * 1977-07-13 1978-10-10 American Cyanamid Company Microcrystalline cellulose as extrusion aid/combustible filler for alumina
JPS59199023A (en) * 1983-04-26 1984-11-12 Matsushita Electric Ind Co Ltd Nitrogen oxide treating apparatus of burning appliance
CN101510612A (en) * 2009-03-31 2009-08-19 哈尔滨工业大学 Method for preparing stephanoporate anode support body using paper fabric a pore-forming agent
CN102503531A (en) * 2011-10-12 2012-06-20 景德镇陶瓷学院 Method for preparing SOFC (Solid Oxide Fuel Cell) anode by adopting spherical and fibrous composite pore forming agent
CN103113129A (en) * 2013-01-31 2013-05-22 华南理工大学 Preparation method and application of hierarchical porous bioactive ceramic
US20130211147A1 (en) * 2011-09-02 2013-08-15 Michael Cheiky Low pressure dimethyl ether synthesis catalyst
CN104876638A (en) * 2015-04-13 2015-09-02 河南工程学院 Pore-forming agent for nanoscale porous ceramics as well as preparation method and application of pore-forming agent
CN106215854A (en) * 2016-09-30 2016-12-14 东莞深圳清华大学研究院创新中心 A kind of coal ash for manufacturing is for the method for ceramic adsorbent articles
CN107266112A (en) * 2017-06-20 2017-10-20 安徽省含山瓷业股份有限公司 A kind of preparation method for the daily porous ceramics for adding composite pore-forming agent
TW201838712A (en) * 2017-03-08 2018-11-01 美商巴地斯公司 Isomerization catalysts

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3856708A (en) * 1972-04-10 1974-12-24 Reynolds Metals Co Alumina catalyst support
US4119474A (en) * 1977-07-13 1978-10-10 American Cyanamid Company Microcrystalline cellulose as extrusion aid/combustible filler for alumina
JPS59199023A (en) * 1983-04-26 1984-11-12 Matsushita Electric Ind Co Ltd Nitrogen oxide treating apparatus of burning appliance
CN101510612A (en) * 2009-03-31 2009-08-19 哈尔滨工业大学 Method for preparing stephanoporate anode support body using paper fabric a pore-forming agent
US20130211147A1 (en) * 2011-09-02 2013-08-15 Michael Cheiky Low pressure dimethyl ether synthesis catalyst
CN102503531A (en) * 2011-10-12 2012-06-20 景德镇陶瓷学院 Method for preparing SOFC (Solid Oxide Fuel Cell) anode by adopting spherical and fibrous composite pore forming agent
CN103113129A (en) * 2013-01-31 2013-05-22 华南理工大学 Preparation method and application of hierarchical porous bioactive ceramic
CN104876638A (en) * 2015-04-13 2015-09-02 河南工程学院 Pore-forming agent for nanoscale porous ceramics as well as preparation method and application of pore-forming agent
CN106215854A (en) * 2016-09-30 2016-12-14 东莞深圳清华大学研究院创新中心 A kind of coal ash for manufacturing is for the method for ceramic adsorbent articles
TW201838712A (en) * 2017-03-08 2018-11-01 美商巴地斯公司 Isomerization catalysts
CN107266112A (en) * 2017-06-20 2017-10-20 安徽省含山瓷业股份有限公司 A kind of preparation method for the daily porous ceramics for adding composite pore-forming agent

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
DHRUBA PANTHI等: "Performance enhancement of strontium-doped lanthanum manganite cathode by developing a highly porous microstructure", 《J APPL ELECTROCHEM》 *
ZHI-PENG LI等: "Mutual Diffusion Occurring at the Interface between La0.6Sr0.4Co0.8Fe0.2O3 Cathode and Gd-doped Ceria Electrolyte during IT-SOFC Cell Preparation", 《ACS APPLIED MATERIALS & INTERFACES》 *

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