Raws li tus neeg muag khoom ntawm graphite bipolar daim hlau, kuv tau pom ua ntej txog kev sib raug zoo ntawm kev laus thiab kev ua haujlwm ntawm cov khoom tseem ceeb no. Graphite bipolar daim hlau yog qhov tseem ceeb hauv cov roj hlwb, ua qhov sib cuam tshuam ntawm cov electrodes thiab sab nraud Circuit Court thaum txhawb kev faib cov roj reactant thiab tshem tawm cov khoom. Kev nkag siab txog qhov cuam tshuam ntawm kev laus ntawm graphite bipolar daim hlau yog qhov tseem ceeb rau kev ua kom lub sijhawm ntev - kev ntseeg tau thiab kev ua haujlwm ntawm cov roj cell.
Lub cev thiab tshuaj hloov pauv thaum laus
Ib qho ntawm cov teebmeem tseem ceeb ntawm kev laus ntawm graphite bipolar daim hlau yog kev hloov pauv hauv lawv lub cev. Sij hawm dhau mus, raug rau cov kev ua haujlwm hnyav hauv cov roj cell tuaj yeem ua rau kev loj hlob ntawm microcracks thiab pores hauv cov khoom siv graphite. Cov kev hloov ntawm lub cev no feem ntau yog los ntawm thermal cycling, mechanical stress, and chemical reactions. Piv txwv li, qhov rov nthuav dav thiab kev cog lus ntawm cov graphite vim qhov kub thiab txias thaum lub sijhawm ua haujlwm ntawm tes tuaj yeem ua rau muaj kev ntxhov siab sab hauv uas thaum kawg ua rau tawg tsim.
Chemically, kev laus kuj tuaj yeem ua rau muaj kev hloov pauv hauv graphite bipolar daim hlau. Ib puag ncig acidic nyob rau hauv proton- pauv membrane roj cell (PEMFC), feem ntau muaj sulfuric acid los yog phosphoric acid, tuaj yeem hnov mob nrog graphite nto. Qhov no tuaj yeem ua rau oxidation ntawm graphite, tsim graphite oxides. Qhov tsim ntawm cov oxides no tsis tsuas yog hloov cov chemistry ntawm lub phaj bipolar tab sis kuj cuam tshuam rau nws cov hluav taws xob conductivity. Oxidized graphite muaj qhov ua haujlwm siab dua piv rau cov graphite ntshiab, uas tuaj yeem txo qhov kev ua tau zoo ntawm cov roj cell.
Kev cuam tshuam rau hluav taws xob conductivity
Hluav taws xob conductivity yog ib qho tseem ceeb ntawm cov graphite bipolar daim hlau. Raws li daim hlau hnub nyoog, lawv cov hluav taws xob conductivity yuav txo qis. Cov microcracks thiab pores tsim thaum lub sij hawm laus tuaj yeem cuam tshuam txoj hauv kev txuas mus ntxiv hauv cov graphite. Tsis tas li ntawd, qhov tsim ntawm graphite oxides nyob rau saum npoo ntxiv impedes cov ndlwg ntawm electrons. Kev txo qis hauv hluav taws xob conductivity tuaj yeem ua rau muaj kev nce ntxiv hauv cov hluav taws xob sab hauv ntawm cov roj hluav taws xob, uas ua rau txo cov hluav taws xob tso tawm. Qhov no yog qhov teeb meem tshwj xeeb hauv cov ntawv thov uas yuav tsum muaj siab - lub zog ceev, xws li hauv cov tshuab roj hluav taws xob hauv tsheb.
Txhawm rau piav qhia txog qhov no, cia peb xav txog cov roj cell pawg nrog cov hnub nyoog graphite bipolar daim hlau. Qhov kev tiv thaiv ntau ntxiv nyob rau hauv daim phiaj bipolar ua rau lub zog poob thoob plaws hauv pawg, uas txhais tau hais tias muaj hluav taws xob tsawg dua rau kev siv sab nraud. Qhov no tsis tsuas yog txo qhov ua haujlwm ntawm cov roj hluav taws xob xwb tab sis kuj tuaj yeem ua rau overheating, vim tias lub zog ntau dhau yog dissipated li cua sov. Overheating tuaj yeem ua kom cov txheej txheem kev laus ntawm cov phaj bipolar thiab lwm yam roj ntawm tes, tsim kom muaj lub voj voog tsis zoo.
Kev cuam tshuam ntawm Gas Permeability
Lwm qhov txiaj ntsig tseem ceeb ntawm kev laus ntawm graphite bipolar daim hlau yog qhov hloov pauv ntawm cov pa permeability. Nyob rau hauv ib lub cell roj, lub bipolar daim hlau yog lub luag hauj lwm rau distributing reactant gases (xws li hydrogen thiab oxygen) tusyees thoob plaws electrodes. Txawm li cas los xij, raws li lub hnub nyoog daim hlau, qhov tsim ntawm microcracks thiab pores tuaj yeem ua rau kom cov pa permeability. Qhov no yog ib qho kev txhawj xeeb vim tias nws tuaj yeem ua rau cov roj hluav taws xob sib txuas, qhov twg cov roj reactant los ntawm ib sab ntawm cov roj cell mus rau lwm qhov.
Gas crossover muaj ob peb yam tsis zoo. Ua ntej, nws txo qhov ua tau zoo ntawm cov roj cell los ntawm nkim cov roj reactant. Qhov thib ob, nws tuaj yeem ua rau muaj kev sib xyaw ua ke ntawm cov khoom siv hluav taws xob, uas tuaj yeem ua rau cov txheej txheem catalyst thiab txo lawv cov haujlwm. Nyob rau hauv qhov xwm txheej hnyav, cov roj hluav taws xob tuaj yeem ua rau qhov hluav taws kub ntawm cov roj reactant, ua rau muaj kev nyab xeeb.
Mechanical Integrity
Cov neeg kho tshuab kev ncaj ncees ntawm graphite bipolar daim hlau kuj cuam tshuam los ntawm kev laus. Txoj kev loj hlob ntawm microcracks thiab pores tsis muaj zog ntawm cov qauv ntawm daim hlau. Qhov no tuaj yeem ua rau lawv muaj kev cuam tshuam rau cov neeg kho tshuab tsis ua haujlwm, xws li kev tawg lossis deformation, nyob rau hauv cov kev ntxhov siab ntawm cov khoom siv thaum lub sij hawm sib dhos roj, kev ua haujlwm, thiab kev thauj mus los.
Piv txwv li, thaum lub sij hawm sib dhos ntawm cov roj cell pawg, cov phaj bipolar feem ntau compressed ntawm cov electrodes thiab lwm yam khoom. Yog tias cov hlau tsis muaj zog los ntawm kev laus, lawv tuaj yeem tawg lossis tawg hauv lub zog compression. Ib yam li ntawd, kev vibrations thiab shocks thaum lub sij hawm thauj mus los kuj tuaj yeem ua rau muaj kev puas tsuaj rau cov laus bipolar daim hlau.
Nto Wettability
Deg wettability yog ib qho khoom tseem ceeb ntawm graphite bipolar daim hlau, vim nws cuam tshuam rau kev tswj dej hauv cov roj cell. Dej yog cov khoom siv los ntawm cov tshuaj electrochemical hauv cov roj cell, thiab kev tswj dej kom zoo yog qhov tseem ceeb rau kev tswj xyuas qhov ua haujlwm ntawm tes. Raws li graphite bipolar daim hlau muaj hnub nyoog, lawv cov dej ntub dej tuaj yeem hloov pauv.
Lub oxidation ntawm graphite nto thaum lub sij hawm laus tuaj yeem ua rau kom muaj hydrophilicity ntawm daim hlau. Txawm hais tias qee qhov qib ntawm hydrophilicity muaj txiaj ntsig zoo rau kev tshem tawm cov dej, kev siv dej ntau dhau tuaj yeem ua rau dej nyab hauv cov pa roj. Cov dej nyab tuaj yeem thaiv qhov ntws ntawm cov roj reactant, txo qhov ua haujlwm ntawm cov roj cell. Ntawm qhov tod tes, yog tias qhov chaw dhau los ua hydrophobic vim muaj cov kab mob sib kis thaum lub sijhawm laus, cov tee dej yuav tsis tuaj yeem raug tshem tawm ntawm qhov chaw zoo, kuj ua rau muaj teeb meem kev ua haujlwm.
Mitigating Cov teebmeem ntawm Kev Laus
Raws li tus neeg muag khoom ntawm graphite bipolar daim hlau, peb niaj hnub tshawb nrhiav thiab tsim cov tswv yim los txo cov teebmeem ntawm kev laus. Ib txoj hauv kev yog siv siab - cov ntaub ntawv zoo graphite nrog kev ua haujlwm zoo dua rau oxidation thiab mechanical stress. Piv txwv li, Graphite Chuck thiab Graphite Base Susceptors ua los ntawm cov khoom siv graphite siab heev tuaj yeem muab kev ua tau zoo thiab ua haujlwm ntev.
Kev kho deg kuj tuaj yeem siv rau daim phiaj bipolar los txhim kho lawv cov kev tiv thaiv kev laus. Txheej graphite nto nrog txheej tiv thaiv tuaj yeem tiv thaiv oxidation thiab txo qhov tsim ntawm microcracks. Tsis tas li ntawd, kev txhim kho cov qauv ntawm cov phaj bipolar tuaj yeem pab txo cov kev ntxhov siab uas lawv tau ntsib thaum ua haujlwm. Piv txwv li, kev siv tus qauv hloov tau yooj yim tuaj yeem ua kom haum rau thermal expansion thiab contraction yam tsis muaj kev ntxhov siab ntau dhau.
Qhov tseem ceeb ntawm kev saib xyuas tsis tu ncua
Kev saib xyuas tsis tu ncua ntawm graphite bipolar daim hlau yog qhov tseem ceeb rau kev kuaj pom cov tsos mob thaum ntxov ntawm kev laus. Los ntawm kev saib xyuas cov tsis xws li hluav taws xob conductivity, roj permeability, thiab txhua yam kev ncaj ncees, nws muaj peev xwm kwv yees thaum twg daim hlau yuav tsum tau hloov. Qhov kev tiv thaiv zoo no tuaj yeem pab tiv thaiv kev ua tsis tiav thiab ua kom lub sijhawm ntev - kev ntseeg siab ntawm cov roj cell.
Xaus
Hauv kev xaus, kev laus muaj qhov cuam tshuam loj heev ntawm graphite bipolar daim hlau, cuam tshuam rau lawv cov hluav taws xob conductivity, gas permeability, mechanical kev ncaj ncees, thiab deg wettability. Cov kev hloov no tuaj yeem txo qhov kev ua tau zoo thiab kev ntseeg siab ntawm cov roj cell tshuab. Raws li tus neeg muag khoom, peb tau cog lus tias yuav muab siab - zoo graphite bipolar daim hlau thiab tsim cov kev daws teeb meem los txo cov teebmeem ntawm kev laus.
Yog tias koj txaus siab rau kev yuav graphite bipolar daim hlau los yog sib tham txog yuav ua li cas los daws cov teeb meem kev laus hauv koj cov roj cell, peb zoo siab tos txais koj hu rau peb rau kev yuav khoom thiab kev sib tham ntxiv. Peb pab pawg kws tshaj lij tau npaj los muab cov kev daws teeb meem zoo tshaj plaws rau koj raws li koj cov kev xav tau tshwj xeeb.
Cov ntaub ntawv
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Zhang, J., & Zhao, TS (2007). Kev tswj dej hauv proton exchange membrane roj hlwb. Phau ntawv Journal of Power Sources, 167(2), 484 - 494.