Yuav Ua Li Cas Zoo Cov Hluav Taws Xob thiab Thermal Conductivities ntawm Carbon Nanotubes? Kev Tshawb Fawb Txog Kev Ua Haujlwm Zoo Raws li cov ntaub ntawv
Hauv cov ntaub ntawv tshawb fawb, ob peb yam khoom tau ntxim nyiam cov kws tshawb fawb tau ntau xyoo zoo li carbon nanotubes. Cov qauv tubular no, muaj tag nrho cov pa roj carbon atoms thiab ntsuas tsuas yog ib kaum -txheej txoj kab uas hla ntawm tib neeg cov plaub hau, suav nrog yuav luag txhua qhov kev cia siab rau tom ntej - tiam supermaterials. Thaum sib tham nrog cov neeg muas zaub, ib lo lus nug invariably tshwm sim: tsuas yog zoo npaum li cas yog cov hluav taws xob thiab thermal conductivity ntawm carbon nanotubes? Niaj hnub no, peb yuav teb cov lus nug no nrog cov ntaub ntawv thiab qhov tseeb.
1. Hluav taws xob conductivity: Electrons sib tw hauv "Superhighway"
Txhawm rau nkag siab txog kev ua haujlwm hluav taws xob ntawm CNTs, ib tus yuav tsum ua ntej txaus siab rau lawv cov qauv. Cov pa roj carbon atoms daim ntawv cog lus ntawm sp² hybridization- ntawm cov tshuaj muaj zog tshaj plaws paub. Hauv qhov kev teeb tsa no, cov khoom siv hluav taws xob tuaj yeem txav tau nrawm ntawm lub raj phab ntsa uas tsis muaj kev cuam tshuam, ib qho tshwm sim hu ua ballistic electron thauj.
1.1 Tus naj npawb Striking: Kaum txhiab zaus uas yog tooj liab
Ob qho tib si theoretical thiab kev sim ua tau zoo heev: raws li cov lus qhia tshwj xeeb, CNTs tuaj yeem nthuav tawm hluav taws xob conductivitieskaum txhiab npaug siab dua tooj liab. Ntawm chav tsev kub, hluav taws xob conductivity ntawm SWCNTs tuaj yeem ncav cuag li 10³ S / cm. Qhov no txhais li cas? Yog tias cov xov hlau zoo ib yam li txoj hauv kev hauv lub tebchaws uas cov hluav taws xob tawm tsam txav mus los, CNTs zoo li yim- txoj kab tsheb loj uas tso cai rau cov hluav taws xob tsis muaj zog.
Ib qho meta- kev tshuaj ntsuam xyuas hauv University of Cambridge tau tshuaj xyuas 1,304 cov ntaub ntawv cov ntsiab lus los ntawm 266 tus phooj ywg- cov ntaub ntawv tshuaj xyuas. Cov kev tshawb pom tau qhia tias doped, ua raws ob peb-walled CNTs (FWCNTs) sawv cev rau qhov zoo tshaj plaws -kev ua haujlwm qeb, nrog cov kua qaub-spun fibers uas qhia tshwj xeeb tshaj yog cov hluav taws xob conductivity. Txawm hais tias cov hluav taws xob conductivity ntawm macroscopic CNT cov rooj sib tham tseem tsis tau ua tiav tag nrho cov tooj liab (tam sim no txog ib qho - thib rau ntawm tooj liab), txiav txim siab tias CNTs tsuas muaj ib feem ntawm qhov ntom ntom ntawm cov hlau, lawv cov conductivity tshwj xeeb (conductivity- rau- qhov sib piv qhov ntom) twb qhia tau hais tias.
1.2 Vim li cas CNTs thiaj li coj tau zoo?
Cov lus piav qhia yog nyob rau hauv quantum mechanics. Nyob rau hauv cov pa conductors, electrons tsis tu ncua sib tsoo thaum lawv txav mus, ua kom muaj zog. Hauv CNTs, vim lawv qhov loj me me thiab cov qauv zoo meej, cov khoom siv hluav taws xob tuaj yeem mus "ballistically" uas yuav luag tsis muaj cua sov. Lub sp² hybridization ntawm C-C daim ntawv cog lus tso cai rau cov hluav taws xob ntawm CNT nto txav ntawm qhov nrawm mus txog 1/300 ntawm qhov ceev ntawm lub teeb, nrog electron txav mus txog 20,000 cm² / (V·s).
Tsis tas li ntawd, nyob ntawm lawv lub siab nyiam, CNTs tuaj yeem nthuav qhia tus cwj pwm ntawm cov xim hlau lossis semiconducting. Cov yam ntxwv tunable no qhib qhov muaj peev xwm loj rau lawv daim ntawv thov hauv cov khoom siv hluav taws xob. Nyob rau hauv 2013, Stanford University tau ua tiav ib qho qauv hauv nruab nrab ua haujlwm tsim los ntawm CNTs. Txawm hais tias nws qhov kev ua haujlwm zaus tsuas yog 1 kHz thaum lub sijhawm, nws tau ua pov thawj qhov ua tau ntawm txoj hauv kev no.
2. Thermal Conductivity: Tshaj Pob Zeb Diamond
Yog tias qhov hluav taws xob conductivity tau ua rau CNTs txaus nyiam rau cov khoom siv hluav taws xob, lawv qhov kev ua haujlwm thermal tau zoo siab rau cov kws tshaj lij hauv kev tswj xyuas thermal.
2.1 Theoretical Limit: 5800 W/(m·K)
Kev kwv yees kwv yees qhia tau hais tias CNTs yuav muaj cov thermal conductivity ntau dua li pob zeb diamond, uas ua rau lawv yog cov khoom siv thermally tshaj plaws hauv ntiaj teb. Cov lej tshwj xeeb yog dab tsi? SWCNTs tuaj yeem ncav cuag thermal conductivity ntawm5800 W/(m·K), thaum MWCNTs ncav cuag 3000 W / (m·K). Rau kev sib piv, pob zeb diamond-qhov zoo tshaj plaws tshwm sim thermal conductor- muaj cov thermal conductivity ntawm kwv yees li 2200 W / (m·K). Hauv lwm lo lus, CNTs tuaj yeem ua cua sov ntau dua peb zaug zoo dua li pob zeb diamond.
2.2 Los ntawm Txoj Kev mus rau Kev Xyaum
Tau kawg, ntsuas qhov thermal conductivity ntawm ib tus neeg CNT yog qhov nyuaj heev. Kev ntsuas thaum ntxov ntawm ib tus neeg MWCNT tau txais txiaj ntsig ib puag ncig 3000 W / (m·K), ua raws li kev kwv yees theoretical.
Ib qho tseem ceeb kom paub meej yog tias thaum CNTs tau sib sau ua ke rau hauv cov ntaub ntawv macroscopic xws li cov yeeb yaj kiab lossis fibers, tag nrho cov thermal conductivity txo qis. Qhov laj thawj yog qhov yooj yim: tube-rau- cov kab sib txuas thiab cov voids hauv cov khoom cuam tshuam cov cua sov. Piv txwv li, thaum SWCNTs raug nias rau hauv ib daim ntawv loj, chav ntsuas -kub thermal conductivity tsuas yog kwv yees li 35 W / (m·K). Qhov no tsis txhais hais tias CNTs lawv tus kheej ua haujlwm tsis zoo; es, nws tseem ceeb tias kev hloov pauv cov khoom tshwj xeeb nanoscale rau cov rooj sib txoos macroscopic tseem yog qhov nyuaj rau kev lag luam.
2.3 Thermal Conduction Mechanism: Lub luag hauj lwm ntawm Phonons
Thermal conduction hauv CNTs feem ntau yog tswj hwm los ntawm phonons. Kev tshawb fawb qhia tau hais tias txoj kev dawb huv ntawm phonons hauv CNTs yog kwv yees li 0.5-1.5 μm. Cov qauv sp² txhawb nqa phonon thauj, muab CNTs nrog lawv cov khoom zoo thermal. Qhov no muaj peev xwm ua kom sov dissipation tau pom kev siv tau. Cov kws tshawb fawb ntawm US National Institute of Standards and Technology (NIST) tau tsim ib qho MWCNT-raws li txheej uas txo cov nplaim taws ntawm polyurethane ua npuas ncauj los ntawm 35%, ua tsaug rau cov cua kub sai sai ntawm CNTs thiab tsim cov txheej txheem tiv thaiv char nyob rau hauv huab cua kub heev.
3. Cov cuab yeej no ua tau li cas hauv kev xyaum?
Cov ntaub ntawv theoretical zoo siab yuav tsum tau muab txhais ua cov ntaub ntawv siv tau. Kev siv CNTs ua cov khoom siv ntxiv hauv lithium- ion roj teeb yog qhov zoo- piv txwv.
3.1 Conductive Network hauv Lithium-Ion roj teeb
Hauv lithium- ion roj teeb cathode cov ntaub ntawv, CNT thauj khoom ntawm kwv yees li 1.5% tuaj yeem ua tiav tib yam li 3% ntawm cov pa roj carbon dub. Qhov tseem ceeb tshaj, CNTs tsim ib qhopeb-sib nqus conductive network. Ib qho -seem CNTs, ua ke nrog cov khoom nquag, tsim lub 3D network uas muaj txiaj ntsig zoo rau kev thauj mus los ntawm cov khoom siv hluav taws xob thiab cov khoom siv tam sim no. Piv txwv li, nrog lithium manganese oxide (LiMn₂O₄) cov khoom, ntxiv MWCNTs ua rau muaj peev xwm tuav tau 99% tom qab 20 cycles, piv rau 90% ntawm cov khoom ntshiab xwb.
Kev ua haujlwm hauv lithium cobalt oxide (LiCoO₂) tshuab yog qhov zoo sib xws. Ntawm 2C tus nqi, LiCoO₂ / MWCNT cov hlwb qhia qhov muaj peev xwm tsawg tsawg, thaum cov hlwb uas muaj cov pa roj carbon dub lossis carbon fibers pom muaj peev xwm poob ntawm 10% thiab 30%, feem, tom qab 20 lub voj voog. Yog vim li cas yog ncaj nraim: lub network conductive tsim los ntawm CNTs tswj kev them nqi thiab txo impedance.
3.2 Tshaj Lithium-Ion roj teeb
Tshaj li cov roj teeb, CNTs tau nkag mus rau ntau qhov chaw:
Aerospace: CNT zaj duab xis tsim los ntawm MIT tuaj yeem ua kom sov thiab kho cov ntaub ntawv sib xyaw, siv tsuas yog 1% ntawm lub zog xav tau los ntawm ib txwm siv autoclaves thaum tsim cov khoom sib piv.
Electronics: CNT-raws li transistors yog me dua thiab ntau dua conductive, muaj peev xwm ua tau zoo silicon.
Zog Cia thiab Thermal Management: Cov ntawv thov tshiab hauv supercapacitors, cov khoom siv thermal interface, thiab lwm qhov chaw tau tshwm sim sai heev.
4. Shandong Tanfeng hauv Kev Lag Luam Kev Lag Luam
Tom qab sib tham txog cov ntaub ntawv theoretical thiab txiav- cov ntawv thov ntug, cia peb rov qab mus rau qhov tseeb tiag. Txawm hais tias cov khoom siv zoo npaum li cas, yog tias nws tsis tuaj yeem tsim los ntawm qhov ntsuas lossis muab kev ntseeg siab, nws tseem yog qhov tsis zoo rau kev lag luam.
Shandong Tanfeng Tshiab Khoom Technology Co., Ltd.yog ib tug tseem ceeb koom nyob rau hauv lub domestic CNT kev lag luam txheej txheem. Raws li kev siv thev naus laus zis- kev lag luam taw qhia rau R&D, kev tsim khoom, thiab kev muag khoom ntawm CNTs, Shandong Tanfeng cov khoom lag luam suav nrog MWCNT hmoov, SWCNT hmoov, CNT conductive paste, CNT conductive masterbatch, thiab silicon - cov ntaub ntawv carbon anode.
Lub tuam txhab tuav ntau tshaj kaum tawm patents ntsig txog CNTs, silicon - cov khoom siv carbon anode, thiab cov khoom siv ntse tsim khoom. Cov patented technologies no ua kom muaj kev ntseeg tau los ntawm kev tsim kho hauv chav kuaj mus rau ntau lawm. Tam sim no, Shandong Tanfeng cov khoom siv dav siv nyob rau hauv xya qhov loj: tsheb tshiab, cov khoom siv polymer siab heev, elastomers, aerospace, tsheb thauj mus los, kev tsim hluav taws xob, thiab hydrogen zog cia.
Rau CNT hmoov, Shandong Tanfeng tau tsim ntau qib, suav nrog TF-210, TF-300, TF-400, thiab TF-500, nrog purity Ntau dua lossis sib npaug li 99% thiab ntev li ntawm 5 txog 15 μm, ua tau raws li cov txheej txheem ntawm cov neeg siv khoom sib txawv. Txawm hais tias ib tus xav tau MWCNTs nrog qhov sib piv siab lossis SWCNTs rau qhov ua tau zoo tshaj plaws, cov kev daws teeb meem tsim nyog muaj.
Tsis zoo li cov neeg muag khoom uas tsuas yog muab cov hmoov, Shandong Tanfeng tseem muab CNT conductive pastes, pab cov neeg siv khoom qis kom tsis txhob muaj cov txheej txheem tshawb nrhiav feem ntau xav tau rau kev tawg. Qhov no yog qhov tseem ceeb tshwj xeeb tshaj yog rau cov tuam txhab roj teeb lithium-ion roj teeb, vim tias kev sib cais CNTs rau hauv slurries tseem yog ib qho kev sib tw hauv kev lag luam. Leveraging nws nyob rau hauv -lub tsev tsim dispersion technology, Shandong Tanfeng xyuas kom meej batch zoo, tso cai rau cov neeg muas zaub tiag tiag "siv tawm ntawm lub hnab."
5. Kev Pom Zoo: Ntawm Kev Ua Tau Zoo thiab Kev Muaj Peev Xwm
Raws li cov ntaub ntawv kws tshawb fawb thiab engineers, peb yuav tsum ceev peb lub qhov muag ntawm ob lub hnub qub thiab hauv av. Cov hluav taws xob thiab thermal conductivities ntawm CNTs yog qhov tseeb theoretical "ceilings," tab sis ob peb qhov tseeb yuav tsum tau lees paub hauv kev siv tswv yim:
Ua ntej, nanoscale zog tsis sib npaug macroscopic zog.Ib tus neeg CNT tuaj yeem muaj qhov thermal conductivity ntawm 5800 W / (m·K), tab sis macroscopic zaj duab xis ua los ntawm CNTs tuaj yeem ua tiav ob peb kaum. Qhov no tsis yog vim muaj qhov tsis txaus hauv CNTs lawv tus kheej, tab sis yog rau lub raj - cov kab mob thiab cov voids hauv macroscopic cov rooj sib tham uas qhia txog cov thermal kuj tseem ceeb.
Qhov thib ob, dispersion tseem yog ib qho kev sib tw tas li.CNTs muaj thaj chaw siab thiab muaj zog van der Waals, ua rau lawv yooj yim rau agglomeration. Yog tias tsis muaj kev cuam tshuam zoo, txawm tias qhov hluav taws xob siab tshaj plaws tsis tuaj yeem ua tiav. Cov khoom ua ntej- cov khoom sib cais uas muab los ntawm Shandong Tanfeng yog lub hom phiaj meej los hais txog qhov mob no.
Thib peb, xaiv cov khoom siv yuav tsum ua kom haum rau daim ntawv thov.Cov kev xav tau rau cov khoom siv ntxiv sib txawv ntawm lithium hlau phosphate (LFP) roj teeb thiab nickel -cobalt-manganese (NCM) roj teeb, nrog rau ntawm silicon -carbon anodes thiab graphite anodes. Rau cov pa hluav taws xob- hom hlwb, MWCNTs muab tus nqi zoo tshaj - ua tau zoo. Rau kev ceev- them lossis silicon-anode systems, SWCNTs yuav xav tau. Shandong Tanfeng's multi{10}}qib khoom matrix yog tsim los muab cov neeg siv khoom yooj yim xaiv raws li lawv xav tau.
Ob peb xyoos dhau los, ntawm kev lag luam exhibition, ib tug engineer tuav CNT qauv thiab nug kuv, "Cov ntaub ntawv rau cov khoom no zoo li impressive. Vim li cas peb tsis tuaj yeem ua tiav cov txiaj ntsig zoo nrog nws?" Thaum lub sijhawm, kuv teb tias: "Cov khoom ntawm cov khoom siv thiab kev ua tau zoo ntawm cov khoom yog ob yam sib txawv. Cov qub nyob ntawm qhov muaj peev xwm; qhov kawg yog nyob ntawm kev txawj ntse."
Kuv tseem tuav qhov kev xav ntawd niaj hnub no. Lub peev xwm tseem ceeb ntawm CNTs yog qhov tsis txaus ntseeg -lawv ua hluav taws xob zoo dua tooj liab thiab cua sov zoo dua pob zeb diamond. Tab sis kev hloov pauv qhov muaj peev xwm ua tau zoo rau cov khoom lag luam ruaj khov, txhim khu kev qha yuav tsum muaj cov tuam txhab xws li Shandong Tanfeng- nrog cov cuab yeej siv patented, kev tsim khoom, thiab kev txawj ntse hauv daim ntawv thov ntau ntxiv - kom hloov "muaj peev xwm" mus rau "kev txawj ntse."
Yog tias koj tab tom nrhiav rau tus neeg muag khoom txhim khu kev qha ntawm CNT hmoov lossis cov khoom siv hluav taws xob, lossis xav tshawb xyuas seb CNTs yuav siv li cas hauv koj cov khoom, thov hu rau Shandong Tanfeng New Material Technology Co., Ltd.