CA2450679C

CA2450679C - Nano-composite electrodes and method of making the same

Info

Publication number: CA2450679C
Application number: CA2450679A
Authority: CA
Inventors: Matthew M. Seabaugh; Scott L. Swartz
Original assignee: Nextech Materials Ltd
Current assignee: Nextech Materials Ltd
Priority date: 2001-06-29
Filing date: 2002-06-28
Publication date: 2010-08-31
Anticipated expiration: 2022-06-28
Also published as: WO2004013882A2; US7595127B2; US20030027033A1; CA2450679A1; WO2004013882A3; AU2002368052A1; AU2002368052A8; EP1527486A2; EP1527486A4

Abstract

A method of making ceramic electrode materials comprising intimate mixtures of two or more components, including at least one nanoscale ionically conducting ceramic electrolyte material (e.g., yttrium-stabilized zirconia, gadolinium-doped ceria, samarium-doped ceria. etc.) and at least one powder of an electrode material, which may be an electrically conducting ceramic electrode material (e.g , lanthanum strontium manganite, praseodymium strontium manganese iron oxide, lanthanum strontitum ferrite, lanthanum strontium cobalt ferrite, etc.) or a precursor of a metallic electrode material (e.g., nickel oxide, copper oxide, etc.). The invention also includes anode and cathode coatings and substrates for solid oxide fuel cells prepared by this method.

Description

NA.NO-C01~FOSITE ~LECTItQpFS AND h'IFTHOp OF MAICiNG TH1; S~MF
RELATFi~ APFLEC 4TLUN
This dpplicat~on claims the benef t of L3.S, provisiQr~al pacerit application No.
60/30?_159. filed tune z9. ?UQ1.
FIELD OF THE INVENTION
ThG invention relates to a method of making ceramic electrode ~nat~rials comprising mixrerres of two or more compor~enrs, including at least otte rcanoscale ioctically conducting ceramic electrolyte material (e.g., yrc~iurn-stabilised zirconia, gadolinium-doped ceria.
samarium-doped ceria, etc.) and at least otte powder of an electrode rns~terial, which may be an electrically cpnduczing ceramic electrode material (e.g , lwchaaum strontium manganite_ praseodymium strontium rna~ganese imn oxide, l~utthar~uri~ strontium ferrite, lanthanum scrorrtium cobalt ferrite, etc.) or a precursor ctf a metallic electrode material (e.g , aiekel oxide, copper oxide, etc.~, as well as electrode products prepared by this method.
Such nana-composi'e electrodes are useful for several electmeherntcal system applications, such as solid oxide fuel cells. ceramic oxygen generation systems, gas sensors, ceramic rnerr~hra.ne aeacrocs, and ceramic electrochei»ical gas separation systems.
v3 ~t~CKGRt)T~p OF THE INVENTION
Fuel cells are envir4nrneutally clean, quiet, and highly efficient devices for generating elecrricitv and heal from hydrogen, natural gas, methanol, propane, at~d ocher hydrocarbon fuels. Fuel cells convert the energy of a fuel directly into energy -electricity and heat - by an elecrrochemtcal process, ~:::hout combustion or moving parts. t~dvama.ges iaciude high U-S. express Mail Receipt No. ~V 07565>4S US
~f~~a ~u~~ zx, ?oQz efficiency and very low release of poilutln~ gages (e g.. N~X) Into the aimosphere_ Of the various types of feet cells, tlse solid oxide fuel cell (SOFC) offers advantages of h,gh efficiency. low materials cost, minimal mairatcnancc, and direct utilization of c=arious hydrocarbon fuels without extensive mformittg. S~FC systems operating with natural gas as a fact can. achieve power generatson effieiesteies In the range of 40 to a5 percent, and even higher efficiencies are possible with hybrid systetxss. Fower is gerserated in a solid oxidt fuel cell by the transport of oxygen eons (from air) tluough a. crrarnic eleerrolyte membrane where hydrogen and carbon monoxide from a hydrocarbon (e.g., nanual gas) are consumed to form waL2r atld carhan d;oxide. The ceramte electrolyte rt'tembrane is sandwiched between electrodes where the power-gettera~ittg aleetrochemieal reactions occur.
Oxygen molecules from air are converted to oxygen ions at the air electrode (cathode), and these oxygen ions react with hydrogen and carbon monoxide to fomt water and carbon dioxide at the fuel electrode (anode).
The sarne types Af matxtials at'e used in most of the SOFC systems currently under development. Compositions used for the ceramic electrolyte membrane material include yttrium-stabilized zit'cotua (YS~), gadolinium-doped czria (GI7C), and samarium-doped cena (S1~C), among otltet~. The air electrode (cathode) is a ceramic material having compositions such as lanthanum suontium manganite (l.Slvl). lantharsutn strontium ferrite (LSF1, tatZthanurn strontium cobalt ferrite (~SCF), samarium strontium cobaitite (S5C), praseodyrntum strorstium mangariite (FSM), and praseodytrsium strontium manganese irons oxide (1'SMF), among others.
The feet el2ctror~e (anode) is a eortsposite (eerrttet) mixture of a ceramic electrolyte material (~.~;., YSZ, GDC or SDC) arsd a metal (e. g., stickel or copper). The anode material typically is produced as a mixture of the electrolyte material (c g , YSZ an GDC) arid the oxide of the metal (nickel oxide or copper oxide); prior to operation of the SOFC, the oxide 1n the composite anode is cedt~ced to the corresponding metal.
Currently, most developtnenta! SOFC systems operate at relatively high temperatures (e e_, 1304 to 954°C~. ~t these high ter;tperaturrs, the electrode trEateriais provide suitable performance using conventional means of preparaiior~ , hioweuer, at these high terrtperatures.
with current an4de materials, hydrocarbon fuels must first be converted to a mixture of hydrogen and carbon monoxide (for example, by reacting the hydrocarbon with stearti): the mixture of hydrogen and carbon m~atcoxide is then delivered Io the SOFC where power is generated. Without this exxerztal "reforming" step, carbon would deposit onto the anodes of the S4FC and pzrformance would degrade rapidly. Operation of SQFCs at lowCr tem~ranues (65o to 75Q°C) would allow internal informing at the anode without carboy deposition. thus reducing size and cost Qf the system and increasing overall officiency. Lower operating tetttperatures also wiil minimize adverse cheraical reactions between component materials, minimize adverse effects of thermal expansion mismatches between component materials.
reduce cost by allowing less expensive metals to be used for interconnects and gas manifolds, and reduce the size and weight of the SQFC power getreraxion system by lessening reRuirements 4n lxeax exchangers and thermal insulation.
However, it 1'tas been diffcutt to achieve high SOFC Power densities at lore temperatures in solid oxide fuel cells because of increased etrfitrolyte resistance and ineffGiency of the electrode tnateriais_ it has been demonstrated that reducing tile thickness of electrolyte membranes lowers electrolyte resistance. This has been achieved in SoFCs with planar gromecries by usir;g one of the porous elecuades (rypicaiiy the anode) as the bulk 5trl~CIUraI support tal?out one millimeter thick). de~siting a dense thin fzlm (about ten microns) of the electrolyte material on the porous anode substrate> and subsequently depositiryg the opposite electroc#e (cathode) as a porous ~tlm (about #°ifty microns) on the elecuatyte film surface_ Very high SOFC power densities have been achieved at temperatures of 7S0 to 800°C
with planar SOFCs produced with this type of configuration. However, even better SOFC
performance and lower temperature opeaaiiort will be achieved by etsmg ~mprovad elecrrode (cathode arrd anode) materials.
Two approaches have been demonstrated for irnprovmS low-temperature performance of cathodes in solid oxide fuel cells. Tltc first approach involves replacement of lanthanum strnneiurca mangat~ite (>-SM), which conducts electricity solely via electron transport, wish rt3ixed-conducting; ceramic electrode materials, c,e., materials that conduct electricity via transport of both oxygen ions and electrons. l=awrrtples of mined-conducting eiecerocle materials include (La,Sr)(Mn,Ca)03 (hSMC), (Fr,Sr)Mn03 (PSM), (Pr,Sr)(Mn,Ca)o~
(PSMC), f La.Sr)Fe03 (LSF), and (f.a,Sr)(Co,Fe)~3 (LSCF). The second approach to improving low-temperature cathode performance involves addition a~ electrolyte rnateria! is the electrode material. This imprnvexnent is due to inereasintg the ~rolt,tme of triple-point (airleleccrndelelectrolyte) regiaus where electrochemical reacnorts accuz.
This enhancement is mast effective is LSM when ceri3-based electrolytes (SDC or Gl;3C) are added or when she partacle size of the componen= (electrolyte annd electrode) materials is reduced. This composite cathode approach also his been shaven to provide enhartcemertts for mixed-canductin~
electrode materials such as I;SF and LSCF.
In order eo irrtpsove anode performance, regardless of operating temperature.
it is desired to reduce ehe respective particle sizes of the metallic and cerartsic components of the cermea anode material. The particle size reduction results in an increase in the volume of triple-po'stxt (gaslnickci~elcctrotyte) regions wltece elecerochrmical reactions occur. When operation via intemsl reforming ~s desired. recta-loosed elecualytes may be preferred over YS2.

:~ccordittgly, there is a need in the an for processes for pFeparir~g improved powder mixtures of ceramic ztactrotyte and elecuode rnatenals, and tcigh-performance anode and cathode materials for solid o~cide fuel cells prepared usi~.g such processes.
Specifically. by achieving these powder mixtures on a tianoseale (e g , less than 100 nm in dimension f.
improved electrode perfortttance will be obtained. Ottrer applications where advanced ClCCtrodr materials are needed include ceramic elecuochetnical gas separation systems. gas sensors. and ceramic ar:embrarse reactors, SuIVIMA~tY ~3F'F~~ ~N'Vrl~°~I4N
One embodiment of the present inventiotl provides a method of malting a ceramic electrode material, including the steps of providing a nanoseale electrolyte powder having a surface area ? ?Q mngram, provsdiag an etecrrode powder, Irtlxlllg the nariC~SCah ~1C'CtratyTe powder with the electrode powder by a mixing method selected from acuitiorx cr~illing and bal!
milling, and calcinirtg the utilled powder mixture. Preferably, Ghe tzanoscale electrolyte powder has a surface area ~ SO rrn/graua, arid more preferably, ? l00 m~/gram. The methAd also may include the step of milling the calcirted powder t'~ixctue or the step of calcining the eiectxoiyte powder before mixing. The mixing step m&y include the steps of milling the electraly~e powder and the electrode powder iti the presence of a surfactartr, dying the milted powder mixture, and sieving the milled powder mixture.
The nanascale elecuolyte powder may be ytuittnn-stabilized zireonia, a doped ceria electrolyte material, bairium xireonate, seandiutrb-dflped zirconia, a lantlsattum gallaEe based ceramic electrolyte material. a bisnttttlt c~x~de based electrolyte material, or a cors~bination xhe-~of ~"he eteeFrode powder may be (1) an etectricatly conducting ceramic material, or ('_') a powder precursor to a metal selected from nickel, copper, and combinations thereof.

V~'hzn the electrode powder is an electricatly conducting ceramic material.
vhe powder mtrtuxe pref=erably comprises ?0 to a~ volume percent of the el2ctcolyte matcrial_ The zlectrodc powder may be a perovskite ceramic electrode material that satisfies the formula t~.,.
~8.~)(C,.YDy)O3_2, where :q. is a lar~thanidc element, I3 is an alE:alirie earth element. and C and D arc trattsitipp elements, preferably lasithant~ttt strontitem martganite, praseodymium strontium mar<ganese iron oxide, lanthanum suattciurn ferrite, lattth~anum strontium cobalt ferrite, lanthanum calcium manga~-tie, Ianthatmm calcitarn cs~balt ferrite, praseodymium strontium mariganitc, praseodymitun strontium ferrite, samarium strontium cobaltite. pr cotttbinations T~l~rG4~.
When the electrode powder is a powder precursor to a metal. the powder tnixrure preferably corstprises 3U to 7~ volume percent of the electrolyte matezial.
ThG trieml precursor may be nickel oxide, nickel carbonate, nickel nitrate, nickel hydroxide, copper oxide, copper carbonate, copper citrate, or combinatic~tts thereof.
Another ernttodinnent of the ittrrention provides a method of rnatcirtg a ceramic elecuode maternal, including the steps of providing a a~scale eiectrolytr powder having a Surface area > _'0 m"gram, providing an electt~de powder comprising oat eiecttically conducting ceramic material, and rttixing the nanoscale eiecuolyte powder with the electrode ppwder by a method selected Pram attrition milling aztd bail milling; and r~lcinirt~ the ttailied powder mixture_ Preferably, the na~oscale electrolyte powder has a surface area > 50 mz~grRm, and more preferably, ? ii30 m°~$ram. The method also may include the step of milling the calc~ned powder mixture or the step of calcining the electrolyte powder befs~re rtaixing. The mixing step may it~ciude the steps of zatihirig the electrolyte powder and the electrode powder in the presence s~f a surfactant, drying the milled powder mixture, arid sieving the milled powder ~nixtt~rc_ .,~ ~ ~ , x ~~__.~._ .. _. _ __~... ~ ..___-_. ___ ' The rcanoscaIe electrolyte pourder may be ytaraatm-stabilized zirconia, a doped corm electrolyte material, barium zirconate, seandiurz -doted zireania, a iaachanstm gallate used ceratztac elecuolyae material. a bisrttuth oxide based eiecrrolyte rrtateriaa, or a combwation tYaereof The powder mi~cture preferably cottcprtses 21~ so S~ volume perceaa elecuolytr powder.
The elecatode powder tttay be a perovskite ce>~atriic electrode maserial that saaisfies the formula (A.,_x8x~(Ci.YDY)~~~, where A is a lanthanide eletteertt, 8 is oat alkaline earth efemena.
arid C and A are arattsiaipn elements, greferably, lattthatmm strontium ananganite.
praseodymitam suonaium ananganese iron oxide, lanthanEuti strontium ferrite.
Ianthapum strontium cobalt ferrite. lantttaaum calcium manganite, Ianaltanutrt calcium cobalt ferrite.
praseodymium stranatum anattgartiae, praseadyt~iual~ stroatium fetriae, samarium suontium cobataite, and combinations thereof The invention alsr~ encompasses a catFtode coating far a solid oxide furl cell in which the coating comprises a ceratrtic electrode tnateriaJ prepared by the above-described process and a cathode subsarate fur a solid oxide fueD cell is which alts substrate comprises a ceramic electrode material giepated by the above-described process.
Yet another eatbodittseni of ahe invention provides a met~tod of making a ceramic elertrocte anaaCrial, ittcludiatg the steps of providing a nauoscale electrolyte powder having a surfare area > ?0 rtazlgram, providing an electrode powder comprising a powr~er precursor to a metal selected from nickel, copper, and combinations thereof, mixing the rtaaaoscalr electrolyte powder with the elecarode powder by a methnd selected from atarition milling and ball milling.
and calcia7ing the milled powder mixaure. Preferably, the r~artoscaie elecuolyte powder has a surface ar$a >_ S~1 rt~'~gram, $nd more pretet~abiy, >_ 100 tatzlgram~ The method also may mcDude the step of milling the calcined pawde~ rtzixaure or the step of ca~eining the electrolyte powder before mixing. The mixing stop m,ay include the steps 4f milling the electrolyte powder and the g electrode powder in the presence of a surfactant, drying the milled powder rniY~ure_ and s~emnT~
the milled powder mixture.
The aanoscale electrolyte powder may ~ yttrium-stabilized zirconia, a eloped eerie ztectrolytr material, barium zirconate, scandiuzra-doped zirconia, a lanthanum galiate based ceramic electrolyte material, a bismuth oxide based electrolyte material, or a combination thereof. Preferably, tile powder mixture comprises 30 to 70 vs~t~e pcreet~t electrolyte powder-The metal precursor taay he nickel oxide, nickel carbonate, nickel nitrate, nickel hydroxide.
copper oxide. copper carbonate, copper niuaie, or combinations thereof The invention also encompasses an anode coating for a solid oxide fuel cell in which the coating comgrisex a ceramic elecuoda material prepared by the above-drscribed process and ats anode subatrate for a solid oxide fuel cell in which the substrate comprises a ceramic electrode material prepared by the above-described grocers.
Another ernhodiment of the ittverttion provides a trsethod of making a.
ceramic electrode material, including the steps of providing a ttanoscale eieclzplyte powder comprising a doped eerie electrolyte tt~aterial having a surface area? 100 tclgiatxt. providing an electr4de powf;er comprising lattthartum strotuittm ferrite, atxi mixing the doped eerie electrolyte aZaterial with the t$rtchant~ strontium ferrite powder by atuition milling or ball milling to form a mixture comprising 20 to 50 volume percent doped eerie electrolyte material. The method also ntay include the step of calcining the milled powder mixture at a temperature of at least 850°C.
Yet another emhoditrtent of the illventiott provides a rriethod of making a ceramic electrode material, inckuding the steps of providing a t:auoscale electrolyte powder comprising a doped eerie electrolyte material having a surface area ? 100 rc~'~grarn~
providing an electrode powder cotxtgrising lanthanum strt~ntium cobalt ferrite. attd mixing the doped eerie electrolyte material with the lat~thanmtl strontium cobalt ferrite powder by attrition milling or Mali ttttlling to form a mixture comprising about ?0 to SQ volume percent doped ceria electrolyze material.
Preferably, the mixing seep as The method also my irsciude the sxep of caicining the milted powder mixture ac a tetttperature of at least g5t3°~.
Still another emhoditrtent of the invention provide a method of cooling a cer3m~e electrode material, inciudi.ng the steps of providing a nanoseaie electrolyte powder havtag a surface area > ?0 m2~~ram, dispersing the electrolyte powder irt water having an adjusted pH <
7, dissolving ati electrode powder in the dispersion, the electrode powder being a water soluble precursor to a metal selected from tiickeh copper, silver, arid cQu~bisiatians thereof adding an aqueous solution of a base to the dispersion to cause precipitation o~the metal precursor on the sacrface of the ttaxwscaie electrolyte powder, need caicitting the precipitated solids. The nanASCale Clectrolyte powder preferably has a surface area ? 50 m2igratrt, and more preferably.
> 100 m''igrarrt. Preferably, the preciptrated solids corriprise 30 to TO
volume percent of tire electrolyte material. The nanascale electrolyte powder cony be ytttrum-stabilised ztrconia. a doped ceria eleccrolyrx material. barium zircanase, scandium-doped zirconia, a IantMaaum gallate based ceramic eiectrplyts tt'tatariah a bismuth oxide based electrolyte rnatrrial. or combinations thereof.
The invention also ertGAmpasses an arcade coating for a solid oxide fuel cell iri which the coating comprises a ceramic electrode material prepared by the ai~Ve-described precipitation prot:ess and an arcade substrate for a solid oxide fuel cell in which the sufastrate comprises a ceramic eleeuode material prepared by this process-Froan the foregoing disclosure and the following ra4re detailed description of various preferred emboditxtertts it will be apparent to those skilled in the art that the present invencaon provides a sigttificattt advance itt the technology and art of ceratriic cathode arid anode materials for solid oxide fuel cells, and other electrochemical device applicatiaos. Particularly .. .. . _.. .,-.~ _...n. ~~ ~, .s, ~ ~ .... _ .
.. . .~
.. rv ._ . . ., r~ a~.w ~u .5<f~ ., ~ ~ ,e. , .W

Sifl7if1C~17t i~ this regard is the pptential the invention affords for improving performance of solid oxide fuel cells, reducing the operating temperature of solid oxide fuel cells. airdfor allowing efficient operation of solid oxide fuel cells with internal reforming of hydrocarbon fuels. Addiciot~I feanues and advattia~es of various prrferred etrtbodirnrnts will be better understood itt view of the detailed descriptit~n provided below.
~RI~F pESCItIP'TIQN tyF TFIE pF~WI~IGS
Figure 1 is an Arrhenius plot showing temperattue decadence of manic conductivtiy for GI~C ceramic electrolyte mai~3ls prepared as described under Example 3 Figure 2 is an Arrhersitas plat shav,~ing cernprrature dcpendeocc of ionic conductivity of perovskite electrode maxerials prepared as deserihed in E~catuple 4.
F~gtue 3 is a Wing electron rntcroscope (SEM) micragraplt of as-produced ziano-corttposite Ni~~YSZ anode powdar prepared as described under Example 6.
Figure 4 is ati SEM micrograph of naao-composite NitJIYSZ anode powder prepared as described under Example 6 and caleitted alt 92S°C for one hour.
Figure 5 is an SEM mierograplz of composire NiOiYSZ anode powder prepared as desczibed citidei Comparative Example 8.
Figure b is an SAM rtiicrograph of rtanascale sintered composite NiO/YSZ anode prepared as described under Example 9.
Figure 7 is art SEM micragtaph of sintered composite NiU~YSZ at~odz prepared as described under Example 9. using powder from Cornpartative Example 8.
Figure 8 is an X-ray dtffractiptt tXRIa) paaern from coclaposite NifJIYS~
anode powder prc~a:~;d as descrihed etndcr ExatrtpIe 1 t.

Figure 9 as an XRD pattern from composite LSF-4AlGDC-30°/a cathode po~.der prepared as described under ~xampte 19.
Figure 10 is an XRI3 pattern from composite LSF-~iU/GDC-40% cathode powder prepared as described under Comparative Example ?0.
Fyure 11 is an XRI3 pattern from composite ~,SF-4t~IGLIC-SO% anode powder prepared as descnl~d under Comparative Example 2 i .
Figure I2 is an X~tp pattern from eorripesite LSF-~fi/GDC-5A% cathode powder prepared as descriia~d under example Z?.
Figure i3 is art ~RD paxteztt frortp cotriposate LSF-2~llGDC-30°!o cathodr powder prepared as described under Exampte 23.
Figure 14 is an XRD pattern from composite LSCF1GDC-3Q°to cathode powder prepared as described under Exampte ?4.
Figure 15 is a plo' stror~ing the effect of calcination terregerattue oa the specific electrode resistance at 800aC for naz~,Q-composite eleCaodes prepared as descri~l under Fxarnples 2Q throu8h ~5.
Figure ifi is $n A;rhetZius plot sltawing temperature dependence of specific electrode res~star~ce of sin~ie-ptaase LSF-4tl electrpdes of Cornpa~ative Example I $, coarse-corapoaite 1_.SF~G~1C electrodes (40 vol% GDC) of Comparative &xatnple 19~ and nano-composite .s 1_S~~fiDC elecuodes (4~1 volp/o GDC) ofExampte 21.
Figure 17 is an Arrhen~us plot showitrg tecz:perature depeadet~ce aF specific elcctr4de resistance of ~~aCF electrodes of Comparative Example 18, and naria-cam.posite LSCF~GDC
electrad2s (30 vol% GDC) of Example ?4.

l7 D~TAa~.il~i~ nES~F~tPTW N ~1F ~~I~ PF~RR~n >E;1~SD~cMErrT~s) Thr present invention inclcidrs processes far preparing intimate mixtures of eeramYc electrolyte and ceramic electrode (cathode or anode) materials comprising a nattoscate powder of an electrolyte material and a powder of an electrode (cathode or anode) material by maxtng thrse two powders in such a way that the eeraxrtic electrolyte powder becomes iaurnately mixed with the electrode powder. The present invention also includes the nalto-.composite electrode (calllode or anode) materials produced by the various processes described iY~
this disclosure.
The nanoscaie electrolyte powder (e.g., Y'SZ or CrDC) has a high surface area > 30 m'Igram, preferably > 50 m°fgram, and more prsferabiy > P QO mzogram.
The nanoscalc electrolyte powder tnay he pxepared by ttydrarhecmaD synthesis or other ~Yetl~ods know to chase skilled irl the art. The rsanoscale electrolyte powder may be a combination of electrolyte powders. The powder electrode materials preferably are micron-sized (or sub-micron svzed), atthQUgh other powder particle sizes also may be used. The powder electrode materials may be a combinat;on of powder electrode rc~mrials.
For a nano-ectmpc~site cathode material, zhe eleetrolytE powder is ct~ixed with an electrode powder that can be arY electrically conducting ceramic eDectrode materiah preferably a pero~sklte ceramic electrode material (e.g., LSM, PSM, pSMF, ~.SF, or LSCF), made by conventional processes of haD1 milling and caDcination, by clYemicaD methods such as the glycitze-nitrate process, or by other means known to those sDcilled itY the art. For a nano-compQSite cermet anode, the electrolyte powder IS mYxed w;th a precursor to the rrYecaf component of thr rermet anode (e.g.. nickel oAYde, nickel carbnnatc). These precursors typically can ire purchased from vattious chemical suppliers as relatively coarsC powders and then reduced in particle size by meehods such as Bali milling or actritic~n milling. .~,lterttativety, cherrttcal tneahods may be used to prrpase preci,trsor tnctal oxides or solid solutions of nickel oxide with other metal oxides, depending ott the desired anode formulation.
The processes used to prepare tiarto-composite cathode tnacerials Qf this invention may include the steps af_ (1) providing a nanoscale electrolyte (e g.. YSZ or GhC) powder, and.
optionally, calcinitig the ztattflscale electrolyte powder to tailor its surface area; t?) preparing an electrode powder (e.~ , LSM, PSMF, f.SF, or LSCF) by lsall milling stoichiotnetric amounts of carbonate andtor oxide precursors, dtyirig and sieving the milled prec~or powder, calcinirig the dried precursor powder mixture to forrri the perovskite crystalline phase, bal! milling or atuition milling of perovskite electrode powder, followed by drying and sieving the milled p~rovskue electrode powder; (3) preparing an intimate mixture of nanascale electrolyte and perovskite elecuade powders by ball milling or attricioa trolling of the electrolyte and electrode powders, optionally with the addition of a suitable surfactant, followed by drying and sieving the nnilled composite powder; and (~4) optionally. calcining the electtolytereirctrode powder mixture at an elevated temperature to tailAr the surface area to that desired for the specific ceramic fabrication method (e g-, tape casting or screen printing) used for making the cathode layers of SOFC electients. Preferably, the resi,eltittg powder mixture cotriprises 20 to 50 volume percent elecualyte material.
The tnethad of making nano-eo~posite anode materials of this invention may include the SI~ps of: (I) preparing a nanoscale electrolyte (e.g., YSZ or GpC) powder arid. optionally.
calcining the nanascale electrolyte powder to tailor its sarf'ace area; (2) obtaining a powder precursor to a metallic electrode tnateriai (e g , nickel oxide or nickel carbonate); 3) optionally.
bail millir;g or atuition milling the precursor powder to reduce its particle size, followed by drying and sieving the milled nickel precursflr powder: (a) preparing an intimate mixture of nanascale electrolyte and nickel precursor powders bye ball tniilitxg or atuition rnillittg of the 1~
_:
elzctrotyte and nickel precursor powders, optionally with the addition of a suiuablc surfactanr_ followed by drying and SlC1Ii11~ of the milled compositr powder: and (5) opuonatly. calcining.
the mixture of electrolyte and nickei precursor powders at an elevated temperature to reducr surface area to that desired for the specific ceramic fabrication method te~g.. tape casting ar screen panting) used for making tl~e anode layers of SUFC elemenrs.
Preferably, the resulting powder mixture comprises 3Q to 70 volume percent electrolyte rrkacerial_ AlEernatiVely, the present method of making nano-composite anode materials may include the steps of ( 1 ) providing a nat~oscale electrolyte powder: (~) dispersing Fhe electrolye powder in water, optionally wash ac~ustment 4f the p1-$ to be ~ 7; (3 ) dissolving an electrode powder in the dispersic~tt, the electrode powder being a water salublr precursor to a metal 1e g., nickel, copper, or silver): (4) adding the dispersion to an aqueous solution of a base (e.g..
ammonium hydroxide or teas methyl ammonium hYdcoxide) to cause precipitation of the metal precursor on the surface of the nanoscale electrolyte powder; and (j) calcming thr precepitared solid product after sepamiir:g .the solid from the suspension.
T'he examples describe preparation of noYel cathode powders based oft ~tar~o-composite mirtures of ceramrc electmlyte material, yttrium-stahili~ed zirconia (YSZ) or gadolinium-doped ceria (ADC). and perovskite ceramic electrode materials, lanthanum strontium mangan~te (LSM) praseodymiurrt strontium manganese ferrite (P~MF)~ lanthanum suonfium ferrite (LSF), and lanthattunr strontium cobalt ferrite (f.SCF), anti novel anode materials based on aano-eQmpasitt rtlixtures of elecualyte material (YSZ or GpC) and nici~el oxide. The ' Cxan~ple rtano-eornposite cathode and anode powders are produced wish surface areas tailored for ceramic fabrication processes (e.g.. tape casting and screen printing) that are commpnly used during she manufacture of planar solid oxide fuel cell elements. 1-lowever, the disclosed processes and nano-composite cathode and anode materials are applicablr to other 1~
comlainauons of ceramic electrolyte and electrode matertals, for applications in solid omde rue!
cells. cerattaie oxygen gcneratiott systems, gas separation systems, ceramic membrane reactors.
and sensors. hurther, Cllr nano-comgasite Electrode powders prepamd as described under the examples can be tailored for use in otl?er types of ceramic fabrication methods, including dry presslrlg, 150Sta;IC pressing, exta~zsion, injeetiori molding, gel casting, and other raerhods know»
In the art.
The terms cathode said anode are used with reference to a SOFC to describe the electrodes of certain preferred embodiuttnts of the invention. Those of ordinary skill in the art will recogni2e that electrodes of tile present ittverttion that fuatctiorl as a cathode or anode, respectively, of a SOFC may have a different function in a different electrochemical system.
These terms are tried for itlusuative purposes anly and trot intended to limit the scope of the invention_ In addition to YSZ and GpC electrolyte materials used for preparing rite example nano-composite cathode and anode raaterials, oar suitable elzctrolyte materials may be used.
These include order doped csria materials (e.g , samarium-doped ceri~, yttrium-doped ceria.
calcium-doped ceria, barium carafe, and ceria~ doped with trnultifrle dopants), barium Zirconate.
scandiurrt-doped zirdpnia, taasthanusrl g~llate based ceramifi eieeaolYte materials, arid bismuth oxide based eleetr4lyre materials.
In addition to LSM, PSMF, LSF, and LSCF electrode materials cased for preparing the exarrlple n~no-corttposite cathode materials. atMGr perovskite electrode materials may be used ill the practice of the present invention. These include lanthanum calcium maatganite (LCM).
lantktsasum calcium cobalt ferrite (LCCF), praseodymitun strontium manganite (PSM), praseodymium Strontium ferrite tl'SF), salnaritlm strontium cobaltite (SSC), or other perovskue clectrsadr marterials having the fnrmtrla (A;.X~x)(C;~YDY)Q~-z> where A is a lanthanide element t6 (e g., Iwa, Pr, Sm, Nd, rrd, Y, etc.), Z3 is an alkaline earth elennenr (e ~., Ca, Sr, or 8ak. and C
and FJ are irar;sitipn elements (e.~,~., lVtrc, Fe, Co. Ni, or Tip. Outer eiectncally condwci,n~
ceramic electrode materials, not mentioned above, also ran be used to prepare nano-composite cathode material using the tnethpds disclosed hetean_ In addition to nickel oxide used far preparing the example nano-composite anode materials, other porsntial metals and~ar metal oxide precursors catzld be used. For nickel-based anodes, potential alternatives to nickel oxide precursors include nickel carbonate, nickel nitrate, and rttckr! hydroxide, among others. For certafat applications, for example, where direct utilization of hydrocarbons is thG preferred SQFC aperatiorsal rr~ode, it might be desired to utilize copper in the anode tttateriats prepared by the subjecE processes;
poEential precursors for copper metal tray include copper oxide copper carrbonate, and copper nitrate, among others. In some instances, improved anode perfortttartce tnay be ot~tained when multiple metals are inrorparared into the anode. In such cases, imvould be beneficial to fast prepare a solid solution of the metal hydroxides (by chemical coprecipitation) or solid solntmn oxides (by coprecipitatiorl followed by calcination) and then co utilize these solid solution precursors wizl~it~ the processes of this invention. In yet other applications, it cony be desired to irrcr~rporace a scnali arnuttnt flf a precious mera.t (e.g., paltadiura.
ruthenium, platinum. or rhodium) into the cerrrtet anoc(e. In these cases, the precious metals vwould be incorporated as precious metal snits at the time when the nanoseale electrolyte material is milled with the primary metal precrtrsor powder.
i~Iowever, as derailed hcrrin, appropriate ac~justmcnts ro the various composinons.
synthesis conduions, processing methods can result in nano~eomposite powder mixturzs than will have utility for solid oxide fuel cell, and otltrr electrochemical device applications.

EXr~Nt~'LE 1 This exarrrple described the preparation of a nanoscale ytutt,uti-doped zrrconta (YSZ) material shat was used in the preparation of nario-composite anodo formulations described w I=xarriples S-7 arid 9-12. Multiple batches of ~arioscaic YSZ material were prepared to prepare thzs2 example anode formula~iott5_ An aqueous suspension of nanoscale, crystalline YSZ ($ mol% Y~43) powder was prepared by coprecipitatiar; to form a hydrous zirconium-yttriunn hydroxide precursor, followed by hydrcrthermal crystallization in an autoclave. A sample of this aqueous YSZ
suspension was dried. and its measured suxface $rea. was i25 m~~gtaan. The product YSZ
suspension was subjected to cross-flow filtratiflrt to remove residual salts and to exchange the water solvent in the slurry with isopropyl alcohol. This Il''a~ slurry of nartoscale YS2 powder was used to make nano-composite anode formulations, as described under Examples S-fi_ Some of this IPA
suspension was dried arrd the resulting narloscale YSZ powder was sieved through a ?QO-mesh scmetz and used for the preparation of nan~-composite anode fcnrtulations described to examples 9-12.
ti'A suspensions of YSZ powder were prepared as described above, arid then dried to a powder. sieved through a 204-mesh screen, and ealeined at 7S0°C for octe hour. Tlte ealcinatiott treatment reduced the surface arra to 75 mZ~gratre. An aalueatts slurry was prepared by adding 75f1 gran~u of caleirted YSZ powder to 300 grams of distilled water, the pH of this slurry was increased to i2.1 by adding 44.75 gtarras of?5% tetramethyl ammonium hydroxide.
and 7.5 grams of citric acid was added as a surfactant. The YSZ slurry then was placed in an attruion mill with about 2500 grains of 3-tom diameter YSZ grinding media. and the mixture was attrition milled for eight hours, dried arsd sieved through a 100-mesh screen. This calcined !~
and attrFnon-milted YSZ powder was uxd ro make namo-composite anode formulations. as described under Example 7.
EXAIv~~~G.~ 3 Th's exacrtple describes the processing of nickel oxide powder that was used for the preparation of narfo-composite anode formulations described in Examples 6, 7, and I ~ _ 1 Q00 grams of as-received nickel Qxide powder (GFS, Lot #~L~i~2152) was aarition mihad for tight with about 2500 grams of 3-xntn diameter YS~ anedia attd about I ~0 groans of isopropyl alcohol. The attritior$-milled slurry was collected, and additiotzal 1~'A was added to reduce the solids contrnt to about 50 wt°io. A sample of this 1PA slurry was dried, arid the surface area of the milled NiU powder was ~.7 m2~gratn (compared to ~.5 m~~gram far tltG NiU
powder prier to milling.
EXa~MpLE 3 This example describes the preparation of naztQSCale gadolinium-doped ceria f~DC) material chat was used for the preparation of ctano-ct~tnposite anode forrctulations descaibed in Examples 13 and 14, and natty-composite c~rtlode fOrfiulaiioc~s of examples 15-24. Multiple batches of narwscale GF~ material were prepared to prepare these example anode and cathode fonnulations_ An aqueous s~spensiot~ of naru~sea,le, crystalline GDC ( 10 rnAlQ~d Gd=tJ3) powder was prepared by coprecipitatron to form ~ hydrous cerium-gadolinium hydroxide precursor.
followed by hydrothertnal crystallization ~~ an autoclave_ The product GDC
suspension was washed in water to remove residual salts. and thcrt in isopropyl alcohol to exchange the solvent.
Thr washing arid solvent exchange was aslaieved by repeating the steps of centrifugation, decantation. solvent addition, and high-shear mixing. Two w.3sh cycles wrr~c performed with water being added after decantation. and three cyctes were performed with isopropyl alcohol being added after decatttataon. A sample of this suspettsi4n was dried, and the surface area of the resulttstg GpC powder was 162 rtZ''Igratrt. This If A slurry was used for nano-compoaitC
anode Iorrnulatiotts described irt ~xamptes 13 and l~.
Art aqueous suspension of rtanoscaie. crystalline (fsDC 10 rnol°~° Cd~G;7 powder was prepared by coprecipitation to form a hydrous Zirconium-yttritvm hydroxide preceusor. followed by hydrathermal crystallization in an auwclave. The pradtzct CrDC suspension was subjected to cross-flow riltratioa to remove residual salts and to Exchangz the vsrazer solvent in the slurry with isopropyl alcohol. This IPA slrtrry was there dried to produce a nanoscaie GDC powder wish a surface area of 15Q rn'Igram, and then used to titake nano-eotnpositc cathode formulati4tis, as described tinder Exarrtples I5, and 2025.
A pottiarr of the aanascale C~i~C powder was ea~lcitted at 793°C for one hour, attritioct milled in ethas:ol for four itoa,trs, arid them dried and sieved through a ?(?0-mesh screen. The surface area of this ealcit~d attd atttitian-naillrd GDC powder was 25 tn~/grawp, arid this powder was used cc ttFahe nanQ-corttposim cathode farmulariotts, as described under Exampie-16-17.
Another portipu of the aanoscale GDC powder was calcified at 80(I°C far 4 hours, attrition milled in isopropyl alcohol with Zireonia grinding trtedia (~-mm cylinders) for b hours.
and than dr;ed and sieved through a 20D-mesh scxeer;. 'The surface area of this coarse GDC
powder was 36.2 tn2~gram, and this powder was used to tttske coarse-cornposize ~iecrrode powders and coatings, as described in Comparative 1=xatnpie 19.
Ce~-atnic samples of the GDC electrolyte trtaterial were made from the above-described GpC powder that was ealcined at 7R3°C. attrition milled, dried and sieved. Two saes of ceramic disc samples were made by isostatically pressing discs (both 3-cm and S-crn irt diameter). and sirtteriog the discs at a temperature of 1375°C far two hours, which grovidC a density of greater than 5~5 percent of theoretical. Bar-shaped specimens of about a-cm in lzngth 7~
,, and 0.?S ctn= in cross-sectional area were cut from the large GDC discs. and these bars ~bere used for sonic conductivuy measurements. hlrctrica! cpntacts were made and stiver lead L~irrs were attached to the GpC bars using platinum ink. Iwlectrical resistance measurements mere made at differ~t temperaeures betwrett 4A0 to x00°C using a digital voltmeter; a constant currant of a few milliamps was applied tlu4ttgh lead wires attached to the ettd of the bars, and the resulting voltage was measured at lead wires in the interior of the bars.
The ionic conductivity was calculated from the measured resistance and the geometry of the test .
specimens. These conductivity data are presented is Figure 1. The measured ionic conductivity ~s among the highest reported in the literettare for GL~C
ceramics of the same composition, which confirms that the GGC ~terial has ~igb quality. A number of GpC
electrolyte discs were made wirh dimensions of about 2-ctrl diameter. aoch faces of these discs were machined flapped) so chat the thiekrtesses were exactly 300 rttiera~.
These discs were used as substrates for screen priutitig ref slrtgle-phase electrode coatizigs (Comparative Example 1$), coarse-carupostce coatings (Corrtpaxative Example 19), ~ca-cc~tnpn~ite elecuade coatings (Examples 20-2S), and subsequent electrical me&suretraents descrii~ed in Example 26.
EXAMP~.~
This example describes the prepazation of praseodym.itun strontium rnaxtganese ferrite (PSI~tF), lantharrurn strontium maregartite (LSM), lanthan~ strontium cobalt ferrite (1.SCF) and t~rttha~nuxtz strontium ferrite (~Sfi) powders chat were used to make nana-composite cathode formulations described irt Examples 1~-Z?. PSMF powder (Example ~.a.) of the composEtiaa (Pro,~,,Srp._fl)(Mt~o;cFe~"~)Q~ was prepared as follows.
~acoichiotrtecric amounts Af praseadytnium carbonate, straatturn carbonate, mang~rtese carbatt~te auid iron oxtdC were bale milled with zirconia grinding media isopropyl alcohol far Z4 hours. The ball-milled slurry was dried and sieved thr4ugh a b0-mesh screen, and then calcified at l~tlQ°C for four hours. The . m. . _ _ _..._._ .,. ,, ..3..a~ ~ ~~._~.w. _.

'~ 1 calcined PSMF powder was then attrition rrMled in isopropyl alcohol far eight fours K ich ;-mm diameter ztrconia gsindittg media, and then dried and sieved through a 1 Qa-mesh screen.
The surface area of this PSMF powder was ~_t3 m~lgracrt. This PSMF powder was used to naal<e nano-composite electrode powders, as dexribed in Fxamples 1S and 1s.
LSM powder of the composition (Lao.~~Src~ es)l~it~3 (~xarnpte 48) was prepared as follows. Stoicltiotnetric amounts of lanthanum carbonate. scronriurn carbonate and manganese carbonate were ball milled with zirconia grinding a~nedia isopropyl alcohol for 2~ hours. The ball rrcilled slurry was dried and sieved through a~ 6Q-mesh screen, and then calcined at 1000 C
far eight hours. The calcirted LSM powder was then attrition mailed in isopropyl alcohol for eight hours with 3-mm diameter zirconia grinding media, azid then= dried and sieved through a 10Q-mesh screen. The surface area of this L.SM powder was 9.S m~/grarri. This 1.SM powder was used to make nano-composite electrode powder, as described in Example 17.
LSF-2Q powder of the composition (~..aq ~pSFp.2~)~~~3 (Example 4C) and LSF-40 powder of the composition (Lao saSrn.~o3Fe43 (example 4D) were prepared as follows.
Staichiometric amounts c~f iartthanttm carbon$te, strontium carbonate and cobalt carbonate and iron oxide were attrition milled with z'trcottia grinding medi$ (3-rnm diameter) and isopropyl alcohol for 6 hours. The attuition~milled slurry was dried and sieved thrr~ugh a. 60-mesh screen, and then calc~ned at 700°C for eight hours. The calcined LSF powders were then attrition milled in isopropyl alcohol for 6 hours with 3-mm diameter zirconia grinding media, and then dried and sieved through a 100-mesh screen. The powder was then re-caicined at ~Sa°C for 8 hours. and attrition milled again for 6 hours to produced a fine LSF powder. The surface areas of the LSF-24 and LSF-40 powders were 9.~Z and 13.9 tr~'-yram, respectively. The ~-SF-20 powder was used to prepare nano-composite electrode powders and coatings, as described in Example ? 3.

The I_SF-&0 powder was used for t~se preparattsaa of single-phase riectrode comings as described in Comparative Example I8, coarse-composite eiectrodr powders and eoatin~s as described m Cortiparative Example 19, and naao-composite electrode powders and coaeinga as described in 3=xamples ? I -23.
LSCF powder of the composition (L.aosasra.ao)(CoozoFeoso)C3 (Example 4F) was prepared as follows_ Stoichiometric amounts of lanthanum carbonate, sus~ntium carbonate and cobalt carbonate and iron oxide were attrition milled with zircoxsia grinding media (3-mm diameter) and isopropxi alcohol for b hours. The attritiQtt-milled slurry was dried and sieved through a b0-mesh screen, and then calciised at 9tlOQC for eight hotus_ Thr calcined LSCF
powder was then atuitiozr milled is isopropyl alcohai for b bolus with 3-riuu diameter urconia grinding media. and then dried arid sieved through a 104--mesh semen. Tile surface area of this LSCF powder was $.9 m2fgrattt. This LSCF powder was used to make single~phase electrode coatings as described iti Corrigarative Exarrriple I8, arid na~tt~-cor3tposim e~Icctrodc Powders and coatings as described in Exarngles 24.25. -Ceramic specimens of the GSM, LSF-2~, 1_SF.4Q attt3 LSCF pemvskite electrode compositions prepared as desctilQed above were made by iso9~cically pressing discs (S-crn in diameter) from the electrode powders, sintering the samples at temperatures of 120 to t-~0o°C, __ eo achieve densities greater than about ~(1 percent of theoretical. far-shaped specimens, about 4-cm itt length and 0.25 ctri~ in cross-sectional area. we;e cut from the discs, and these bars were used for electrical conductivity measurements. !electrical cantact$ were made and Sliver lead wires were artached to the bars using platiatun ittk. Electrical resistance measurements were made at differet;t temperatures between 4Qfl to 800°C acing a digital ~Qitmeter; a censtaat cuTi'cnt of a few rr3i11iaixips was applied through lead wires attached to the end of the bars, and tl~e resuftirlg voltage was rileasured at lead wires in staC iritertol of the bars. The iotzic conductivity was calculated from the measured resistaaice arid the geometry of the test specimens. These conductivity data fur the prrovskite electrode triaterials are presented in Figure ?. ~'he measured electricaf conducttviry far each of these materials is consistent with that reported in the literature for similar eorrtpasitions, which conf rats that these perovskitC
electrode materials were prepared wit~t high quality.
1_xarnples S, 6, arid 1 describe the preparation of a nano-composite an4de fors~ulation based on a mixture of nickel oxide (Ni0) arid yttrium-ssabilized zircoziia (corresponding to a nickel metal content of 43 voiturie percent afrer reduction of Ni0 to Ni merat), with controlled surface areas.
EXA~VIPI.te S
282.5 grams of the !PA slurry frsxm Example 1 (containing 99.5 grains of nanoscalc Y5Z powder). 1~~.14 grants of as-received nickel oxide powder (IFS. 1_ot #i.40? f 6Z). and about 50 ml of additional isopropyl alcohol was pfaced in an attrition mill with alsaut 3300 grams of 3-mm diameter 2irconia grinding media. This starry was attrition milled for eight hours and then dried and sieved through a Z00-mesh screen. Pows~er samples (?-3 grams) were then caicined at various temperatures and surface areas were measured. polo for surface area versus calcirtation tQrnperature are provided in Table 1. eased on those data.
100 grams of tlZia mixed powder was calcined at 800°C for one hour. and l3S grams of powder was ealcined as ~?S°C far one hour. resulting in surface areas of 19.~ and 19,1 m~igram, respectively T'ahle 1.
Surface areas (in units of tn'~gram) for c~ctned ti~t>O-c4CtlpoSiiE' ~leccrode powders calcmed ac different temgeramres_ T (C) Ex. 5 Ex. 6 E~- 7 Ex. I3 Ex. 14 Ex. 1~

?S --- 49.1 3I.6 64.0 --- 65.3 ~,pp ___ ___ ~_ ___ ___ ?7.8 7D0 ___ ___ 37.m :;9.5 ___ 18.8 X50 2~i.3 ?b.4 __- 19.5 24.2 __ 80p 23.0 21.1 I9.5 16.1 17.19 _--850 ___ ,__ ___ ___ ___ 8.D

9QQ I3.8 13.9 1~.4 8.5 --- ---925 8.5 9.$ 12.I1 _-- ___ S.p 9Sa 7.8 9_ 1 6.5 ___ I ~ .S ___ 1 pp~ ___ 7.1 S.3 5. ( ___ ___ EXANfFi.E 6 290 grams of IPA slurry of rtanosca;e Y5Z powder (froth ~xarripEe 1, containing 204.25 gams of YSZ) and 5$3 grains of the attrition-milled IPA slurry (from Exat~plC ?.
containing ?95.75 grains of ~fi0) was placed irt a four-Iiter naigene jar with 6300 BramS of zireonia ~rindiag media (~-tnm and 10-mm Cylinders). This combined slurry was ball rra~fled far 24 hours. dried, and then sieved through a 20~-mesh screen. The surface area pf this nano-composite anode powder was 49. t rta'-lgratn. ~'owder samples (~-3 grams) were then calcined at various temperatures and surface areas were rrteasured. Data for surface area versus calcirtatton temperature ate provided in Table 1. used on these data, ID~
grams of dais rntxed powder was calcined at SOD°C for one hour. arid 20t3 grams of powder was caicined at 9?a°C

for one hnur. resulting in surface areas of 19.9 and 9-8 m'/grarrt, respectively. SW1 rsticragraphs showjpg the morphology of as-dried and calcirled nano-c~mposire powders of rhw example are shown i~1 Figures 3 arid A. These rnicrc~gra~hs show chat the nanoscale YSZ
material has corned the surfaces of the coarser aickrl oxide particles, and that this coatcd-powdcr rrtorphotogy ~s rerairaed as ~e materials is ealcined w 925°C.

SSS.3 grams of the attritipn-milled IPA sleury {frorxt Example 2. containing 295.75 grams o f Ni~) and 2t74.2S grams of calGined Grad atuitiQrt~milled YSZ powder (frora Example 1 ) was placed in a one-Iiter nalgene jar with ZIOp gi-$ms of zirconia grindizag media (S-trim and 1 Q-cm cylinders}. This powder mia..nue was ball milled for 24 hours, dried, and rhea sieved through a 2~0-mESh screetz. The surFace area of this rtana-cQm,posite anpde pewder was 31.56 tru/gram. Powder samples (2~3 grams) were ~ben c$lcined at various terriperatures and surface areas were measured. Data fox surface area versus calcirtat#ot~ temperature are provided is Table 1 based on these data, 1 (34 grams of this r~na-cot~posiie mode powder was calcined at 7St!°C faF one hotu, and ?Q0 gtarns c~f powder was ealcined at 925°C for one hour. resulting in surface areas of 2~.0 and 8.9 rnzlgrarn, respectively.
CC1M~~.RATIV~~~CAMPLE 8 This example iltusuates the corlventioraal approach fo making anode (NiOIYSZ) fprmuta~iart, which involves bail milting of relatively coarse YSZ and Ni0 raw material powders. The anade formulauoa prepared was hatched to have a cc~uipnsision corresponding to 59,1 ~F weight gercrr~j ctickel oxidr (which correspor4ds rca 43 volume percent nickel resent afrer reducuonofleti(~ to Ni cnera.p,). ?9_S7 grams of nickel oxide (GFS. Lot #L4fl21b3, Q.5 rn'igram) and 20.14 grams of YSZ (Tosoh, Lat # 28096aP, 10.7 m-'~gram) were ball milled with zirconia grinding media isoprs~pyl alcohol far ? 1 hours. The bail-milled slurry was dried and sieved .. ~. ~ ~,.. ,. ~,._ . ~ .M . r . . .*.. ~: ,~.. -. _ ._..._ .

7~
:z througtl a ?00-mesh screen This anode m~xmre had a surface area of powder was 6.60 m'yram. Atz SEM rtticrograph of thrs powder (sl3own ire Figure S) shows that two disnncc phases are evident, including a coarse nickel oxide panicle attd agglomerates of fitte~scaie YSZ
powder. r~ very poor distribution of NiCa and YSZ phases is evident, compared ca the SE~1 micrographs of harm-camposxte anode powder of ~xarr~ple 6 the were presented in Figures 3 and 4.
E MP~,9 11 ! .0i grams of r~anoscale YSZ, with a surface area of 135.33 m~lgrarci, was dry milled with ! 88.99 g of NiC3 (Novamet High Purity Green Ni(3-Citade F) t4 achieve a homogeneous mixture with a target Ni metal content of ~? vnltune percent. The resulting mixture was then placed in a I liter attrition mill container with apprflximately 25U0 grams of ~-mm diameter ceria-stabilized zireauia media and 2E30 ml of issxptopyl alcohol. The material was milted far 6 hours to achieve inuxnate mixing. The powder was removed aszd dried at room temperature, then sieved through 1~0 mesh prior to calcirtatiott. The Surface area of the as-milled powder was 41.75 m'Igratn. 'flte surface ,tea was tailored for tape castitxg by calcining the as-milled powder for 4 hams at 900RC to achieve a surface area of 9_S m~lgram. Using a commercial binder systerrt9 a slurry was prepared containing i3.~ vfllume percent NiC?-YSZ cornposi~e powder, and S.7 valtame percent maitodextria (Pure pent B-83fl, Grain Processing Corporat,on) to produce a ceramic body with intercannectcd porosity upon casting and sintering. The tape was slowly heated to 600°C to remove border and then sintered at 1275°C for orte hour to densify the cnatenal. The resulting cntcrostrtrcture is shown in Figtue 4. A
microstructure of a cape prepared using material synthesized by the process described in Comparative Example 8 is shown in Figt;re ?. This material was sintered at l4t~A°C foe I hour to achieve a ~imiiar ?7 y sintered density (5~°~° p",) The difference ~n relative grain sizes of the nickel and YSZ phases is clearly zvident from the micrographs. and irtZpCrwed anode performance wrould be expected for the finrr-scale mierostrucxure achieved using the nano-cortlpositc approach of this exarttple.
The difference i~ sintering performance can be directly aarihttted to the surface area of the natiascale material its relation to the comparative material. This cotnpositc powder is also suitable for the developt:zent of screen printing inks.
~xA s ~o,~, Example 1Q decaiis the synthesis of a nanoscaie precursor powder by an acrd-base preeipicacian_ This maEeriai is further processed to snake YSZ-Ni0 composite powders in Examples l I aad 12.
EXaMPGE 10 18.73 grams of nanocrystalline YSZ powder, with a surface area of l 35.33 m''yram_ was dispcracd in water and pH adjusttedd ca 3 usi~ nitric acid. To This suspet~sian, 125.2 grams of nici;ei nicrare was added" lo produce 47 voiuzrie percent nickel upon reduction of the resttiting powder. The z:itrateloxide suspettsio~ was tittated into a 2 moral solution of tetrarrcethylammonium hydroxide; the final pH of the reaction prade~ct was 13.9. The resuhing preclp~tate, comprised of natia~crystaiiisze YSZ coated with an amorphous rttckel hydroxide phase, was segregated from the supernatant by centrifugitkg the suspension at 3000 RPM far 13 minutes. The t~rsulting cake$ were divided and processed as de~scrihed in h~camples 1 l and l?.
E;~
Material from hxanap~e 10 was redispersed its lOtlp tttl of isopropyl alcohol isy shear mtxmg at ?000 RPM for eve minutes. The suspension was Fhcn centrifuged again and the supcrnatam discarded. The process ,was repefried a second time, to complete the removal of 7~
zxcess sails and water. After the third centrifu~atioa~ step, the product w a~
dried in a convection oven ac 60QC for lb hours. then ground and sieved through ?00 mesh pnor io catcmauon. The ~owdrr was cat~ined at 400-1004°C to canve~ the amorphous nickel hydroxide unto nickel oxide and to remove arty residual organic groups. X-ray diffraction.was perfarmed to ascertain the crysrat str;tctttre of the materials; ttte resulting patterns as shown in Figure 8. The surface area of the poEVCler afrer caleiaiation at X00°C
was a9.OS mngram.
Fu~fter modi~catio~zs to surface area were made by increasing ilae caicination certiperaeure:
these dar$ are retarded i~ Table 2.
Taste 2. Surface a~as (ire units of m2lgra~) For calcined nano-c~rnposite electrode powders calcined at different ceuigeratures.

Temp (C) 11 13 ;5 ib 17 2Q Z1 ax 3~ 24 2S

23 59.0 .-- 65.3 1$.l 18.~i 76.$ 97.3 b7.6 120.3 52.9 60tf ~S.2 --. 2'7.x ---. ___ _._ __. _. ___ ___ 7pp 37.6 ___ 18.$ --- .__ ___ ___ ___ ___ ___ ___ 7gp ___ 22.4 ___ ___ ___ ~_ __ ___ ___ _._ ___ $A4 26.9 17.2 --_ __. ___ ___ ~_ ~ _M

83t1 _-- _-- 8.0 .__ __,. g,6 _,_ ~_ 9.3 10.3 -__ 9~1(! 22.9 ___ ___ ~ ___ ___ 6.6 7.4 7.7 5.6 6.9 7.8 92g ~_ .__ 3_0 ___ ___ _w _~ ___ ___ ___ _,_ 9Sp ___ t l .S ~_ ___ ___ 7.2 7.1 6.4 4.6 b.7 6.7 lp4p _~ ___ __, __, ___ S.l 3.0 4.7 3.6 4.$ ~.6 lp5p ~ ___ ~_ ~_ ___ __ ~ ___ ~.3 ~ 3.8 ~ ___ 3..~
~ ---?9 .., EX~ivI I~"~?
~iatetial fi-stn Example I~ was redispersed in 1040 m1 of act aqueous solution of tetrarstethyl amrt~oniurn hydroxide (pH-12) by shear tttixing of ?~00 ~"M for five minutes- The suspension was rhea ceasrifuged again arid the supernatant discarded. The process was rrpeated a second time, to cntnplete the removal of excess salts. After the third eentFifugacion step, the product was redispersed a fttai tune itt I L of water and placed in a ttydrothermai reactor for 1 hour at ?4t1°C. Tire crystallization reaeti4n toots place under autogeneous prassure and continuous agitation. ~'he resuitirtg product seated lay cstttrifugation and dried in a convection oven at 1 ~t1°C for 16 hours. The resultistg powder was sie~red through ?00 mesh and evaluated by XRII:? and surface area analysis. X-ray diffrartiort cottfirnaed that crystatlinc nickel hydroxide fQt~ned during the hydrothetmal reactinn. which was converted to nickel oxide as the material was ealcined at higher tesrsperattues.
~~'L~13 $~
~xatztples 13 arid 14 describr ehe preparation of a Santa-composite strode Formulation based ost a mixture of nickel oxide (NiQ) and gadoliniuttt-doped ceria~
(corresponding to a nickel metal content of 43 volume percent after reduction of Nz0 to Ni mescal), with controlied surface areas.
EXA1~~'~~E 13 137 grasps of an 1PA slurry of nanoscale GDC powder (from Exampie 3, containing _'2&.63 grarsts of GEC) arid X34 grams of the attrition-actillcd 1PA slurry (from example ?.
contatttittg 21.35 gear's of hliQ) was placed in a ~out~~liter nalge~ne tar with 6340 grams of zirconia grinding trtedia (Q.~S-inch and U.~-inch eylinders). This combined slurry was ball mined far ?4 hours, dried. and rhea sievrd through a 2DU-mesh screen. The surface area of This nasxo-composite anode powder was 6..45 trsngxa:m- Powder samples (?-3 grams) mere c~ccn calcincd ac variclttS Ceeriperatures end surface areas were rr~easured. Data far surface area versus calctnation temperature are provided iri Table t Based on these dataa 1U0 grams of this nano-composite anode powder was calcinect aE 75U°C for one troetr, tesulur2g in a surface area of '_'?.-i snZlgrarrr.
EXAMFI_1= 14~
3U~.3U grams of the IP.~ slurry frorr~ Example 3 ~cantaining I00.2 grams of naaoscale GDC pawde;), l 1x.93 grams of as-recei~cd nicleel oxide gciwder (GFS, Lot ~L40216?) and about !U0 ml of additional isopropyl alcohol were placed ia. ~ attcitiou mill with about 35UQ
gams of 3-men diarneEer zirconia grinding media. 'this slurry was attrition milled for eighe hours and then dried and sieved through a 200-mesh screen. 'Fhe surface area of this r~arlo-composEte hIiGIGDC anode powder was 80.7 raei2~gram- Powder samples (~-3 grams) were then calcincd at various temperatures and sw~face areas were measured.. Data for surface area versus calcination temperature ate provided in Table I. Based on these data., i00 grams of this r~ano-composite anode powder was calcitied at 750°C for one hour, resulting irl a surface area of 2~.7 mngram_ EXAIV1,~L~S ~,~-?2 l;xamples 1 ~-22 descrsbe the preparation of a nar<o-composite cathode formulations based ors a mixtures of perovskite electrode materials (PSMF. I-SNI, LSCF, and LSFI and gadolinaurtx-dapeGi ratio (correspc~uding co a CaDC conrera of 30 oc 40 volume percent>, with space areas 5-34 tr~2lgraFn iwhich are suuabte for screen prituiag).
EXAIviFLt~ 15 287.6 gracrls of PSMF powder (from l;xampte 4) and ? 12.4 grams of naaascale GDC
powder (fmm 1<xarnple 31 were glared in an attrition mill with about 2500 graters of 3-mm ~1 diameter ztrcoma grinding media and about 2~U mt of ~sopropyi alcohol. This slurry uas attrition spilled for eight .hours and then dried and sieved through a 200-mesh screen. The surface area of this nano-carrtposite catt~odr powder was 18.1 m'~gratr;-Powder samples (?-.i grams) were then calcined at various temperatures and surface areas were measured. pate for surface area versus calcination tempetaturc are provitted in Table 1. used on these data. l d0 grart3s of this na~to-cnmpostte cathode powder was calcitted m b35pC far one hour, resultittb in a surface area of 2~.1 m2~grarn.
EXA ~ 16 ?87.6 grains of PSIwIF powder (from Exarzlpie ~A) anti 212.4 grams of calcined and attrition-trilled ~iDC powder (from Example 3 ) were placed in an aiu'ition rr3i11 with about ,~~DO
grams of 3-mm diameter zircotiia gtittding media and about 2~0 ml of isopropyl alcohol. This slurry was a~tia~ milled far eight hours anr3 then dried atld sieved through $
204-mesh screen.
The surface area of this -cornposixe cathode powder was 18.1 m'/.
E~~PL E 17 ? 1 ~.$7 grams of LSIv~ powder (frotrt Fxat~ple 413) and l 5,25 grates of calcined and attritiorx-milled GDS powder (froth Example 3) were pieced itt an attricio~, mill with about 2500 grains of 3-mm diameter ureottia grinding tttedia and about 2t14 ml of isopropyl alcohol_ This slut~y was attrition rtiklled for eight ltotus and then dried and sieved through a f0-mesh screen.
TIZe surface area of this nann-composite cathode powder was l8.fi mzlgratrl.
coMy.~~'~vF.~~I~~P~'~ 1$
Samples for elecuica! testing were prepared using single-phase perovskite electrode powders, itsrludirig ~-SF-~Q (Exarttpie ~3D) and 1_5CF (Fxatnple 4E)_ Screen-printing inks were prepared by dispersing 7 grams of LSF-4D or ~.S~F powder info a commercial terpineoi-based ink vehicle (~eraeus, No. V-Ot)b)> using a three-rflit trill. 'fire solids content of the inks was j7 about ?~ ~roiurne percent. anti the viscosity was about 19 Pa-sec at D;s''.
Cueular patterns (D.?7 erra diameter) were deposited by screen printing onto opposite faces of the 3Q0-micron GD3C discs from Example ~. The electrode-coated CrDC discs were then anrteaDed at 950°C for 1 hours so chat the electrodes adhered to the GDC discs. After annealing, thicknesses oi' the electrode coatings were about SO txticrons for both samples. hlectrical testing of these sampizs was perforated, as described under Example ~E:.
CGMPARATI~tI~ EXAM~'~ 19 9o.~ grams of coarse GDC powder that was calci~ed at ~OOpC and ball sxtilled (front >rxample 3) were combined with 82.09 grams of I ~F-~~ powder from Example aD
to form a ~0 volume percent GDC powder ttiixture. The pourders were mixed by ball tnillit~g with zirconia grinding media arad isopropyl alcohol. The ball-milled slurry was dried and sieved through a 100-mesh screezi. All XRD pat~errl from the resulting powder is shown in Figure 9.
'fhe mixed powder was calcin~d at 1040°C w proddee a composite powder with a surface area of 4.? ltl-tgram. t~ sereerl-prinrin~ ink was prepared by dispersing 5 gams of composite powder into a. cotrunercial terpttreol-based ink vehicle (I-~eraeus, No_ V-006) using a three-roll mill. The solids contem of ttze inks was atmul 3t~ volume percerst and the viscosity was about 2U Pa-sec at ! 3 s' ~ . C ircular paiterris ( I -?7 em diameter) were deposited by screen printing onto opposite faces of the 300-tt~icran GDC dies fxom Example 3. The electrode-cQatecl GDC disc was then annealed a19~0°C for 1 hours so that the electrodes adhered to the GDC discs. After annealing. thielcr;esses of the electrode coatings were about 50 microns.
Elecuical testing of this sample was performed, as described under ExampDe ?~.

J.1 EXANIPLp ?0 304.4? grams of LSF-~0 powder (froth Exartiple 4A) and 95.8 grams of narsoscale GDC powder (fsam Example 3) were rttixed to form a 30 volume percent GhC
mixture. -the powder was placed gn an attrition null with about 2500 grams of 3-mm diameter zireonia grinding media and about 200 mi of isopropyl alcohol- This slurry was attrition mired for six hours and than dried arid sieved tluough a 200-mesh screen. The surface area of this nano-composite e'eccrac3e powder was 52.94 m~lgram- ~~~n paccem ft4m r.tie rrsuhing powder is shown in >=igure 10. Powder samples ( t ~~20 grams) were Then calcined ac various temperatures and surface areas were rrteasured. Data for surface area versus calcinatiors temperature are pro'~~ded its Table 2- Screen-prinntig inks were prepared for nanc~-cotraposiie electrode powders caleinec~ as 854, 9U0, 950, and I X10°C. These inks were prepared by dispersirxg 5 grams of composite powder into a comtxaeseiai terpincol-based ink dehiela (Heraeus, Ielo. V-p061 Using a three-roll rrxiIl. The solids corrterit of Ghe irtics was about 30 volume gercenx arid the viscosity was about 20 Pa-sec at i3 s';. Circular pactems (1.27 ctxa di~meeer) were deposited lsy screen printing ~nro opposite faces of ci?e 304-rnicrAn GDC discs from Exaszipie 3.
The electrode-coated G~3C disc was tlnea~ annealed ac 9S0°C for ~ hours so that the eiec'rodes adhered to the GhC discs. After annealing, thicknesses of the electrode cQacings were about a0 microns.
~irctrieal testing of this sample Was performed, as described under &xansple ?6.
EX~~,~I_E 21 I7a.? grams of ~SF-40 powder (from Exarasple ~i3) arid 127.1 grams of nanascalc GAC
powder (from Example 3) were mixed to form a 40 volume perceatt GI~C mixture.
The powder was placed in an aterition rrsill with about 3500 grams of 3-mrn diameter zirconia grinding media artd about ?AO ml of isopropyl alcohol. This slurry was ,atxri~ion milled far six hours arid a~
thin dried a.nd saeved throc~gh a 200-mesh screen. 'fhe surface area of this nano-carnpos~~z eleezroc3e powder was ~b.76 mZ~grarrt. An 3CRL~ pacrem froth the resulting powder is showc~ a Figure 11. Powder samples ( I S-2U grams) were clan catcined a~ various cemperarures and surface areas were measured Bata for surface arCa versus calcinarion temperature are promded in Table ?. Screen-printing arks were prepared for nano-coruposite elecuade powders caic~ned at 854, 900, 9gfl, and 1000°C. These inks wefie prepared by dispersing S grams of cocrlposiie powder mro a commercial zerpi~ol-bawd irk veluclr (Heraeus, No. V-p05) using a three-roll mill. The solids conrenr of the inks was about 3p volume percem acrd Ehe viscosity was atom ?D Pa-sec aE 13 s {. Circular patterns t 1.27 crci diameter) were deposited by screen printing a~trr~
opposcze faces of clte 300-rr~icron GDC discs from l;xample 3. The elrccrode-caared. GDC disc was then annealed at 950°C for 1 hears so tl3at the electrodes adhered to the GDC discs. Aver aru~eaiirtg, rhicknesses of the electrode coatings were about 50 microns.
FIectrical testing of this sample was perForttmd, as described tinder Example 26.

I4~i. l 9 grains of LSF-40 powder (from Eacart~lple 4I3) and I 56.03 graTt~s of nanoscale GDC powder (from Example 3 ) were mixed ro form a SO volume percei;t GDC
mixture. The powder was placed in an attrition trill with about 3500 grams of 3-mm diameter zircania grinding media and about ?00 ml of isopropyl alcohol. This Slurry was aiuiiion milled for six hours and then dried and sieved rhraugh a 200-mesh screen. ArA XItD pattern from she resttljing powder is shown in Figure I2. The surface aces of rltis t~ano-composite electrode pow-der was 97.29 src-Igram. Powder samples E 1 S-20 grarris) were then calcined at various temperatures and surface areas were measured. L)ata for surface area versus ealcina~ion temperature are provided in Table 2. Screen-pcic~iing inks were prepared for horn-composite electrode powders calcined at 850. X40, 950, and 1000°C. These inks were prepared b.
dispersing 5 grams of conipos;te powder into a commercial tecpineolrhased ink vehicle (Heraeus, No. v-00~) using a three,roll rrtill. 'fhe solids cont~eat of the inks was about 3D
volume percent at~d the viscosity was about 20 Pa-sec at 13 s ~. Circular patterns ( 1.?7 cm diameter) were deposited by screen priarai~g onto oppostte faces of the 300-micron GDC discp from Irxample 3, The electrode-coated CrDC disc was then aruiealed at 9~0°C for 1 hours so that clte electrodes adhered to the GDC discs. After annealing, dticlaoesses of she electrode coatings were alaout ~0 microns. ElecErical Eestirtg of this sample was performed, as described under Fxatnple ?f.
EXAlV~PLp ~3 ?04.42 grams of LSF-20 powder (from, lExarttple 4C) and 95.5$ grams of nanoscale GDC powder (from ~xample 3) were mixed to form a 30 vo3ume percent GDC
mixture. The powder was placed in art rtttxitiort mill with about 2500 gas of 3-mnt.
diarr~;er zircania grinding media and about 20D ml of isopropyl alcohol. 'this slum was attrition milled for six hours arid then dried and sieved through a 2D0-tttesh screen. Act XRD pattern from the resulting powder is shown in Pigtere i3. Powder samples f IS-?0 grams) were then calcined at various temperatures and surface areas were measured. Bata for surface area versus calcirtaoion temperature are pravidCd itt Taktle 3. Scceerz-pritttittg inks were prepared for nano-corrtpos,te electrode powders ':a)cined at X50, 900, 9$0, and 1004°C. These inks were prepared by dispersing 5 grams of cotrxposite powder into a eorsutyereial tecpineol-based irttc vehicle (1-leraeus, No. v-006) using a three-roll mill. The solids content of the inks was about 30 voiurcie percent and the viscosity was about 20 Pa-sec at 13 s '. Circular patterns ( 1.37 cm diameter) were deposited by screen printing onto opposite faces of the 300-micron GpC discs _s from example 3_ The elecuodr-coated GDC disc was then annealed at 9~0°C
for 1 hour, ;o that the elecuodes adhered to the GpC discs. after atlnealirlg, thieknesse~s of the electrode coatings were about 50 microns. ~lectncal testit:g of this sample v~ras performed, as described under Example 26.
~xAM~~LE ~~ .
202_g? groans of LSCF powder (from ~xairaple 4E) and 9?.08 grams of zlanoscale GAC
powder f from ~xatttple 3) wens tztixed to farm a 3D voiuttt$ percent GpC
mixture. The powder was placed is an attritiotl rni31 with about 350Q 8rurls of 3-enm diameter zirconia gendln~
media arid about ?00 ml of isopropyl alcohol. This starry was attrition tnilletl far six hours arid then dried aid saeved throc~8h a 200-thesh screen. ~l.n, XR.p portent from the resuEting powder is shpwn in Figure 14. T11G surface area of this narlo-cornpasite c$thode powder was 67.56 m'~gt~am. Powder samptes ( 15-20 grams) were then calcined at Various temperatures anc3 surface areas were meastued. pata for surface area versus calcination temperature are provided itt Table 2. Screett-printing !irks were prrpared fox natto-corr:posite electrode powders calcined at 8~0, 900, 950. and 100U°C. These inks wrre prepared by d~spersing ~
grams of composite powder into a comtnet'cial terpitteoi-leased iitlEc vrhicle (Hetaeus, No_ V-oOC~) usinS .a chrrc-roll mall- The solids content of the itvks was abauT 30 volume percent and the viscosity was about 30 Pa-szc at 33 s t. Circular gatterits ( 1 _?7 em diameterf were deposited by screen printing onto opposite faces of the 300-micron G13C discs from Exa3rtpie ~. 'f he aleettode-coated GDC disc was then ~ntlealed at 9S0°C for 1 hours so that the electrodes adhered to the GDC discs. After annealing, thicknesses of the elecuAde coatings were about s0 microns.
~lECtrical testing of this sample was performed. as described under Example 26 aa~.. ___ ~ ._ ,.;
_ ___ ___._ _.___..~. ~~ ~_ " ~ ~ ._ _...n_._._._ E'C~.M~~1= ~5 131.7b grates of L5C'~ powder (from ~xampie 4E) and 15824 grams of nanoscale GDC powder (from hxatttple 3) were mixed to form a 50 volume percent CrDC
mixture. The powder was placed ira an attrition rraiii with abattt 25Q0 grattas of 3-mm diameter ~irconta grinding rr~edia arid about 200 tnl of isopropyl alcoltAl. TElis slurry was atrxtuara milled far six hours and Then dried and sieved through a 204-mes#t screen. T'he surface area of this nana composite cathode powder was 13(1.34 m''~gratat. Powder satrtples ( i 5-20 grams) were then calcirsed ai various temperatures Grad surface areas wee mrasutrd. pz~ta for surface area versus calcanation temperature are provided in Table ?. Screed-printing inks were prepared ft~r ttana composite electrode powders calcined at 850, 900, 950, and 1000°C.
These inks were prepared by dispersing 5 grates of composite powder into a commercial terpine4l-based ink vehicle (Heraeu', No. ~l-X46) using a three-roEl mill. The solids content of the inks was about 30 volume percens and the viscosity was about 20 Pa-sec at i 3 s '. Circular patterns ( 1.27 crrt diameret) were deposited by screen printing onto opposite faces of the 3Q0-micron GDC discs frartt Example 3. The elee~ode-coated GDC disc was then atutealed at 95G°C far 1 hours so chat the electrodes adhered eo the GDC discs. After annealing thicl~nesses of the electrode coattrags were about 50 microns. hlnetrical testing of this sample was perfatTnrd. as describzd s~ under example 26.
Ex~lvt~~
The GpC discs with eEectrodr coatings, prepared as described in ~,xampEes 18-25, were subjected to electrical testrztg to verify the beneficial effects obtained by using the nano-composite eleetrndes and methods far preparing these naua-cbtnposite electrodes. The same measurement protocol was used far all samples. Silver paste was applied to the elecuode surfaces. and two silver lead wires were attached to each electrode face. :~
digual volcmeter was used to measure the resistance of the electrode GL7C discs at temperatures between ~t00 and SOA°C. ~°wo resistance measurements were made ax each temperature iwith oppasEte polarities), the average of the two resistance measurements was determined and recorded. This resistar:ce corresponds to the fatal of the ohmic resistance ofthe GI3C
eleetralyte, the resistance associa;ed with the ariLerfaCes between the electroiyce arid eiectrodes (where elecuochemtcai reactions take place), and Fhe ohmie resistance of the eiecuodes themselves (which is negligible)- The resistartee assQCiated with the GDC elecrrQl3'te was calculated from the specimen geometry using ionic Conductivity dava obtained an GU~C ceramics as described cinder example ~ (see Figure 1 ). A.feer subtFacting thG electrolyte component. the resulting resistance value was assumed to be the resistance associated with the elecuodes. which was primarily due to interfacial resistance. the specific elecuode resistance (or normalized to the electrode area) value was calculated by multiplying by the electrode area ( l .?67 cm' ) and divtdit~g by two (the number of electrodes per s mple). For mast applications, target values for speci#'tc electrode resistance are about A.15 S3-cm~ or Iower at the operating temperature.
Results ofthe electrical tneastaretnents are summarized by data presented in Figures iS.
16. and 17. It is vety apparent that the nana-composite apprr~aeh> when proper caleinatiort COtldltlonS are used prior to preparaiiott of screen-pnrzting inks, provides significant pcrfonnance advantages cotrtpared to either the sirtgle~-phase peravslCite elecerode materials (sez Figures I S and 16), or coarse-COmpo~iie electrode materials tree Figure 16).
The importance of using a high surface area G1~C electrolyte powder aa~ coaiunctaora with the process for rnakmg nana-compasete electrodes is clearly shown by eiecuode resistance data obtained far Examples 19 and ? 1 tree Figure 16). Nazfo-cotr~posite 1_SF~GDC electrodes prepared from a GDC

powdzr with a surface area of abam 36 cra°igsam (Fxaanple 19) had much higher ekeearadc resutances than nano-corrsposite I-SFWDC electrodes prepared from a GI3C
powder with a surface area of about 150 m2/gtam (1=xarnple 31 ) R!k of the electrode materials reared showed the wane type of temperature dependence.
warh a~ change in slope of Arrhenius plots, correslsortding ro higher activation energy at lower temperatures and tower activation energy at higher teanpcratutes. This can ire explained on the basis of electrode performance being limited by poiarWion (i.e_, charge crat~sfer) at lower temperatures and by mast trarispc~rt (e.e . conductivity) at higher temperatures. The nano~
comgosire approach irnprovcs electrode performance aver the ettrire temperature range of the measurCaneaats, but this effect was mo,t pronot~raced at lower tempeaatures iaa the gotarazatian-daanireated regime.
As shown in Figure 17. it is critical that the proper ea.~einatic~n temperature is used after mixiatg of the eiecaalyte and electrode powders in order to ac<lieve the lowest ekectrode resistance. 'Fhe perfatzttance of etch of the narto-cotnpflsne electrode formulation is anodulared try the starting surface areas of the ce~mponcm materials, the relative volume fraeaions of each catnponent. and the calcination rearapet'arua'e used after mixing and before preparatipn of scr een-printing inks. ~f the Cak~nadors temperature is too high, then performance can be degraded rather by a'eacrian between the two phases or due to loss of active surface area far reaction.
When the ealeinatian teanperature is too low. the performance can be degraded due to poor particle-to-panicle contact (and toss of electrical conductivity) in the highly conducaave pzrpvskcitc phase. The opramum calctnation ternperarure depends on specifics of tic formulation (e.g, relative volurrta fractiAns of tacit phase. and the starait~g particle size and surface area of each phase, the degree of niixedness achieved prier to caleinauon, and the surface area of the nano-composite powder after calciraation. ~y fakiawing the teachings of this patznt, one east descgn an optimum nano-eomposate electrode material for a Pmen set uC en~i-member composttians.
ThroughQUt this speca~casion, when a range of conditions or a gror~p of substances is defined wuh respect eo a particular characteristic (e ,~_, temperature, time, and the like) of clue presena invention, the present invention relates to and explicitly incorporates each and every specific member and combination of sub-r~~es or sub-groups therein. Any specified range or group is to be understood as a shorthand way of referring tc~ each and every member of a range Qr group individually as well as each and every possible sub-range arid sub-group encompassed therein; and similartY with respect to any sub-ranges oz sufa-groups ihemin.
Thus. for example.
a time of 10 to I S mFt~utes is to be understood as specifically incorporating each and every individual time, as well as sui~-range, such as, far example, I I minutes, I2 minutes, la to I3 minutes, I 0.~ to 15 minutes, I O to 1 ~ rtzinutes, etc.
From the foregoing disclosure anal detailed description of certain prefezxed embodiments, a will be apparcttt =hat various modifications, additions and other alternative embodiments are possible without departing front the scope and spirit of the present invention. The embodiments discussed v~ere ctec~sen and described to provide the best illusuation of the principles of the present invention and its practical application to thereby enable one of ordinary shill in the art to use the invention itt various embodiments and with various rt;odifications as are suited tc~ the particular use cQntempiaced. All such modifications and variations are withizt the scope of the present invention as determined by the appended claims when interpreted in accordance with the benefit to rv~hich whey are fairly, legally, and zquitabiy entitled. The descriptions and disclosures herein are intended solely for purposes of illustration and should not be construed as limiting the Scope of the present invention which is described by the following claims.

Claims

WHAT IS CLAIMED IS:

1. A method of making a ceramic electrode material, comprising the steps of:
providing a nanoscale electrolyte powder having a surface area ~ 20 m2/gram;
providing an electrode powder; mixing the nanoscale electrolyte powder with the electrode powder by a mixing method selected from attrition milling and ball milling; and calcining the milled powder mixture.

2. The method of claim 1, wherein the nanoscale electrolyte powder has a surface area ~ 50 m2/gram.

3. The method of claim 1, wherein the nanoscale electrolyte powder has a surface area ~ 100 m2/gram.

4. The method of claim 1, further comprising rite step of:
milling the calcined powder mixture.

5. The method of claim 1, wherein the mixing step comprises the steps of:
milling the electrolyte powder and she electrode powder in the presence of a surfactant;
drying the milled powder mixture; and sieving the milled powder mixture.

6. The method of claim 1, further comprising the step of:
calcining the electrolyte powder.

7. The method of claim 1, wherein the nanoscale electrolyte powder is selected from yttrium-stabilized zirconia, a doped ceria electrolyte material, barium zirconate, scandium-doped zirconia, a lanthanum gallate based ceramic electrolyte material, a bismuth oxide based electrolyte material, and combinations thereof.

8. The method of claim 1, wherein the electrode powder is selected from (1) an electrically conducting ceramic material, and (2) a powder precursor to a metal selected from nickel, copper, and combinations thereof.

9. The method of claim 8, wherein the electrode powder comprises an electrically conducting ceramic material and the powder mixture comprises 20 to 50 volume percent of the electrolyte material.

10. The method of claim 8, wherein the electrode powder comprises a powder precursor to a metal and the powder mixture comprises 30 to 70 volume percent of the electrolyte material.

11. The method of claim 8, wherein the precursor to a metal as selected from nickel oxide, nickel carbonate, nickel nitrate, nickel hydroxide, copper oxide, copper carbonate, copper nitrate, and combinations thereof.

12. The method of claim 8, wherein the electrode powder is a perovskite ceramic electrode material that satisfies the formula (A1-x B x)(C1-y D y)O3-Z, where A is a lanthanide element, B is an alkaline earth element, and C and D are transition elements.

13. The method of claim 12. wherein the perovskite ceramic electrode material is selected from lanthanum strontium manganite, praseodymium strontium manganese iron oxide, lanthanum strontium ferrite, lanthanum strontium cobalt ferrite, lanthanum calcium manganite, lanthanum calcium cobalt ferrite, praseodymium strontium manganite, praseodymium strontium ferrite, samarium strontium cobaltite, and combinations thereof.

14. A method of making a ceramic electrode material, comprising the steps of:
providing a nanoscale electrolyte powder having a surface area ~ 20 m2/gram:
providing an electrode powder comprising an electrically conducting ceramic material:
mixing the nanoscale electrolyte powder with the electrode powder by a method selected from attrition milling and ball milling; and calcining the milled powder mixture.

15. The method of claim 14. wherein the nanoscale electrolyte powder has a surface area ~ 54 m2/gram.

16. The method of claim 15, wherein the nanoscale electrolyte powder has a surface area ~ 100 m2/gram.

17. The method of claim 14, further comprising the step of:
milling the calcined powder mixture.

18. The method of claim 14, wherein the mixing step comprises the steps of milling the electrolyte powder and the electrode powder in the presence of a surfactant:
drying the milled powder mixture; and sieving the milled powder mixture.

19. The method of claim 14, further comprising the step of:
calcining the electrolyte powder.

20. The method of claim 14, wherein the nanoscale electrolyte powder is selected from yttrium-stabilized zirconia, a doped ceria electrolyte material, barium zirconate, scandium-doped zirconia, a lanthanum gallate based ceramic electrolyte material, a bismuth oxide based electrolyte material and combinations thereof.

21. The method of claim 14, wherein the powder mixture comprises 20 to 50 volume percent of the electrolyte powder.

22. The method of claim 14, wherein the electrode powder is a perovskite ceramic electrode material that satisfies the formula (A1-X B X)(C1-Y D Y)3-Z, where A
is a lanthanide element. B is an alkaline earth element, and C and D are transition elements.

23. The method of claim 22. wherein the perovskite ceramic electrode material is selected from lanthanum strontium manganite, praseodymium strontium manganese iron oxide, lanthanum strontium ferrite, lanthanum strontium cobalt ferrite, lanthanum calcium manganite.

lanthanum calcium cobalt ferrite, praseodymium strontium manganite, praseodymium strontium ferrite, samarium strontium cobaltite, and combinations thereof.

24. An cathode coating for a solid oxide fuel cell, the coating comprising a ceramic electrode material prepared by the process of claim 14.

25. An cathode substrate for a solid oxide fuel cell, the substrate comprising a ceramic electrode material prepared by the process of claim 14.

26. A method of making a ceramic electrode material, comprising the steps of:
providing a nanoscale electrolyte powder having a surface area ~ 20 m2/gram;
providing an electrode powder comprising a powder precursor to a metal selected form nickel, copper, and combinations thereof;
mixing the nanoscale electrolyte powder with the electrode powder by a method selected from attrition milling and ball milling; and calcining the milled powder mixture.

27. The method of claim 26, wherein the nanoscale electrolyte powder has a surface area ~ 50 m2/gram.

28. The method of claim 27, wherein the nanoscale electrolyte powder has a surface area ~ 100 m2/gram.

29. The method of claim 26, further comprising the step of:
milling the calcined powder mixture.

30. The method of claim 26, wherein the mixing step comprises the steps of:
milling the electrolyte powder and the electrode powder in the presence if a surfactant;
drying the milled powder mixture; and sieving the milled powder mixture.

31. The method of claim 26, further comprising the step of:
calcining the electrolyte powder.

32. The method of claim 26, wherein the nanoscale electrolyte powder is selected from yttrium-stabilized zirconia, a doped ceria electrolyte material, barium zirconate, scandium-doped zirconia, a lanthanum gallate based ceramic electrolyte material, a bismuth oxide based electrolyte material, and combinations thereof.

33. The method of claim 26, wherein the powder mixture comprises 30 to 70 volume percent of the electrolyte powder.

34. The method of claim 26, wherein the powder precursor to a metal is selected from nickel oxide, nickel carbonate, nickel nitrate, nickel hydroxide, copper oxide, copper carbonate, copper nitrate, and combinations thereof.

35. An anode coating for a solid oxide fuel cell, the coating comprising a ceramic electrode material prepared by the process of claim 26.

36. An anode substrate for a solid oxide fuel cell, the substrate comprising a ceramic electrode material prepared by the process of claim 26.

37. A method of making a ceramic electrode material, comprising the steps of:
providing a nanoscale electrolyte powder comprising a doped ceria electrolyte material having a surface area ~ 100 m2/gram:
providing an electrode powder comprising lanthanum strontium ferrite; and mixing the doped ceria electrolyte material with the lanthanum strontium ferrite powder to form a mixture comprising 20 to 50 volume percent doped ceria electrolyte material, the mixing method being selected from attrition milling and ball milling.

38. The method of claim 37, further comprising the step of:
calcining the milled powder mixture at a temperature of at least 850°C.

39. The method of claim 38, further comprising the step of:
milling the calcining powder mixture.

40. A method of making a ceramic electrode material, comprising the steps of:
providing a nanoscale electrolyte powder comprising a doped ceria electrolyte material having a surface area ~ 100 m2/gram:
providing an electrode powder comprising lanthanum strontium cobalt ferrite and mixing the doped ceria electrolyte material with the lanthanum strontium cobalt ferrite powder to form a mixture comprising about 20 to 50 volume percent doped ceria electrolyte material, the mixing method being selected from attrition milling and ball milling.

41. The method of claim 40, further comprising the step of:
calcining the milled powder mixture at a temperature of at least 850°C.

42. The method of claim 41, further comprising the step of:
milling the calcined powder mixture.

43. A method of making a ceramic electrode material, comprising the steps of:
providing a nanoscale electrolyte powder having a surface area ~ 20 m2/gram;
dispersing the electrolyte powder in water having an adjusted pH < 7;
dissolving an electrode powder in the dispersion, the electrode powder being a water soluble precursor to a metal selected from nickel, copper, silver, and combinations thereof;
adding the dispersion to an aqueous solution of a base to cause precipitation of the metal precursor on the surface of the nanoscale electrolyte powder; and calcining the precipitate solids.

44. The method of claim 43, wherein the nanoscale electrolyte powder has a surface area ~ 50 m2/gram.

45. The method of claim 43, wherein the nanoscale electrolyte powder has a surface area ~ 100 m2/gram.

46. The method of claim 43, wherein the nanoscale electrolyte powder is selected from yttrium-stabilized zirconia, a doped ceria electrolyte material, barium zirconate, scandium-doped zirconia, a lanthanum gallate based ceramic electrolyte material, a bismuth oxide based electrolyte material, and combinations thereof.

47. The method of claim 43, wherein precipitated solids comprise 30 to 70 volume percent of the electrolyte material.

48. An anode coating for a solid oxide fuel cell, the coating composing a ceramic electrode material prepared by the process of claim 43.

49. An anode substrate for a solid oxide fuel cell, the substrate comprising a ceramic electrode material prepared by the process of claims 43.