Cov roj teeb lithium-ion feem ntau yog tsim nyob rau hauv cov kev taw qhia ntawm lub zog siab ceev. Nyob rau hauv chav tsev kub, silicon-raws li tsis zoo electrode cov ntaub ntawv alloy nrog lithium los tsim lithium-nplua nuj cov khoom Li3.75Si theem, nrog ib tug tshwj xeeb muaj peev xwm txog li 3572 mAh / g, uas yog ntau dua li theoretical muaj peev xwm ntawm graphite tsis zoo electrode 372. mAh/g. Txawm li cas los xij, thaum lub sij hawm rov qab them thiab tshem tawm cov txheej txheem ntawm silicon-raws li tsis zoo electrode cov ntaub ntawv, cov theem hloov ntawm Si thiab Li3.75Si tuaj yeem tsim cov ntim loj loj (kwv yees li 300%), uas yuav ua rau cov txheej txheem hmoov ntawm cov khoom siv hluav taws xob thiab kev tsim tawm tas li. SEI zaj duab xis, thiab thaum kawg ua rau lub peev xwm poob sai. Kev lag luam feem ntau txhim kho kev ua haujlwm ntawm silicon-raws li tsis zoo electrode cov ntaub ntawv thiab kev ruaj ntseg ntawm silicon-raws li roj teeb los ntawm nano-sizing, carbon txheej, pore tsim thiab lwm yam technologies.
Cov khoom siv carbon muaj qhov ua tau zoo, tus nqi qis, thiab qhov chaw dav. Lawv tuaj yeem txhim kho cov conductivity thiab kev ruaj ntseg ntawm cov khoom siv silicon. Lawv nyiam siv los ua kev txhim kho kev ua haujlwm ntxiv rau silicon-raws li tsis zoo electrodes. Silicon-carbon cov ntaub ntawv yog lub ntsiab kev loj hlob ntawm silicon-raws li tsis zoo electrodes. Cov pa roj carbon txheej tuaj yeem txhim kho qhov kev ruaj ntseg ntawm cov khoom siv silicon, tab sis nws lub peev xwm los inhibit silicon ntim nthuav dav dav thiab tsis tuaj yeem daws qhov teeb meem ntawm silicon ntim expansion. Yog li ntawd, txhawm rau txhim kho kev ruaj ntseg ntawm cov khoom siv silicon, cov qauv ntxeem tau yuav tsum tau ua. Pob milling yog ib qho kev lag luam rau kev npaj nanomaterials. Cov khoom sib txawv lossis cov khoom siv sib txawv tuaj yeem muab ntxiv rau cov slurry tau los ntawm pob milling raws li cov qauv tsim ntawm cov khoom sib xyaw. Lub slurry yog tusyees dispersed los ntawm ntau yam slurries thiab tshuaj tsuag-qhuav. Thaum lub sijhawm ziab sai sai, nanoparticles thiab lwm yam khoom siv hauv slurry yuav ua rau tus yam ntxwv ntawm cov txheej txheem ntxeem tau. Daim ntawv no siv cov khoom lag luam thiab ib puag ncig tus phooj ywg pob milling thiab tshuaj tsuag ziab tshuab los npaj cov khoom siv silicon porous.
Kev ua tau zoo ntawm cov ntaub ntawv silicon tuaj yeem txhim kho los ntawm kev tswj cov morphology thiab faib cov yam ntxwv ntawm silicon nanomaterials. Tam sim no, silicon-raws li cov ntaub ntawv uas muaj ntau yam morphologies thiab faib cov yam ntxwv tau npaj, xws li silicon nanorods, ntxeem tau graphite embedded nanosilicon, nanosilicon faib nyob rau hauv carbon spheres, silicon / graphene array ntxeem tau qauv, thiab lwm yam. Nyob rau tib lub teev, piv nrog nanoparticles. , nanosheets tuaj yeem ua kom zoo dua qhov teeb meem crushing tshwm sim los ntawm ntim nthuav dav, thiab cov khoom muaj ntau dua compaction ceev. Kev tsis sib haum xeeb ntawm nanosheets tuaj yeem tsim cov qauv ntxeem tau. Txhawm rau koom nrog silicon tsis zoo electrode pauv pawg. Muab qhov chaw tsis rau qhov ntim nthuav dav ntawm cov khoom siv silicon. Kev taw qhia ntawm cov pa roj carbon nanotubes (CNTs) tuaj yeem tsis tsuas yog txhim kho cov khoom siv hluav taws xob, tab sis kuj txhawb kev tsim cov txheej txheem ntxeem tau ntawm cov khoom vim nws cov yam ntxwv ntawm ib sab morphological. Tsis muaj cov ntaub ntawv qhia txog cov qauv ntxeem tau tsim los ntawm silicon nanosheets thiab CNTs. Daim ntawv no siv cov khoom siv pob zeb milling, sib tsoo thiab dispersion, tshuaj tsuag kom qhuav, carbon pre-txheej txheej thiab calcination txoj kev, thiab qhia porous txhawb nyob rau hauv cov txheej txheem npaj los npaj porous silicon-raws li tsis zoo electrode cov ntaub ntawv uas tsim los ntawm nws tus kheej-assembly ntawm silicon nanosheets thiab CNTs. Cov txheej txheem kev npaj yog yooj yim, ib puag ncig tus phooj ywg, thiab tsis muaj cov kua khib nyiab los yog cov khoom pov tseg raug tsim tawm. Muaj ntau cov ntaub ntawv qhia txog cov pa roj carbon txheej ntawm cov khoom siv silicon, tab sis muaj qee qhov kev sib tham tob txog cov nyhuv ntawm txheej. Daim ntawv no siv asphalt raws li cov pa roj carbon monoxide los tshawb xyuas cov teebmeem ntawm ob txoj kev txheej txheej carbon, kua theem txheej thiab txheej txheej txheej, ntawm txheej txheej thiab kev ua haujlwm ntawm cov khoom siv tsis zoo silicon-based electrode.
1 Kev sim
1.1 Kev npaj khoom siv
Kev npaj ntawm cov khoom ntxeem tau silicon-carbon composite feem ntau suav nrog tsib kauj ruam: pob milling, sib tsoo thiab dispersion, tshuaj tsuag kom qhuav, carbon pre-coating thiab carbonization. Ua ntej, hnyav 500 g ntawm thawj zaug silicon hmoov (hauv tsev, 99.99% purity), ntxiv 2000 g ntawm isopropanol, thiab ua cov pob ntub dej ntawm lub pob milling ceev ntawm 2000 r / min rau 24 teev kom tau txais nano-scale silicon slurry. Cov tau txais silicon slurry yog pauv mus rau lub dispersion hloov tank, thiab cov ntaub ntawv yog ntxiv raws li loj piv ntawm silicon: graphite (tsim nyob rau hauv Shanghai, roj teeb qib): carbon nanotubes (tsim nyob rau hauv Tianjin, roj teeb qib): polyvinyl pyrrolidone (tsim nyob rau hauv Tianjin, analytical qib) = 40:60:1.5:2. Isopropanol yog siv los kho cov ntsiab lus khoom, thiab cov ntsiab lus ntawm cov khoom yog tsim los ntawm 15%. Sib tsoo thiab dispersion yog ua nyob rau ntawm ib tug ceev dispersion ntawm 3500 r / min rau 4 h. Lwm pawg ntawm slurries tsis ntxiv CNTs yog muab piv, thiab lwm yam ntaub ntawv yog tib yam. Tom qab ntawd cov slurry uas tau txais dispersed yog muab xa mus rau lub tshuab ziab khaub ncaws, thiab cov tshuaj tsuag kom qhuav yog ua nyob rau hauv ib qho chaw tiv thaiv nitrogen, nrog rau qhov kub thiab txias ntawm qhov hluav taws xob yog 180 thiab 90 ° C, feem. Tom qab ntawd ob hom carbon txheej tau muab sib piv, txheej txheej txheej thiab kua theem txheej. Cov txheej txheem txheej txheej txheej yog: cov hmoov qhuav qhuav yog tov nrog 20% asphalt hmoov (ua hauv Kaus Lim Kauslim, D50 yog 5 μm), tov rau hauv lub tshuab tov khoom rau 10 min, thiab kev sib xyaw ceev yog 2000 r / min kom tau txais pre-coated hmoov. Cov txheej txheem ua kua theem yog: cov tshuaj tsuag-qhuav hmoov ntxiv rau cov tshuaj xylene (ua hauv Tianjin, qib tshuaj ntsuam xyuas) uas muaj 20% asphalt yaj hauv cov hmoov ntawm cov ntsiab lus ntawm 55%, thiab lub tshuab nqus tsev stirred tusyees. Ci hauv lub tshuab nqus tsev qhov cub ntawm 85 ℃ rau 4h, muab tso rau hauv lub tshuab tov khoom rau kev sib tov, qhov sib tov ceev yog 2000 r / min, thiab lub sij hawm sib tov yog 10 min kom tau cov hmoov ua ntej coated. Thaum kawg, cov hmoov ua ntej coated tau calcined nyob rau hauv ib lub qhov cub rotary nyob rau hauv ib qho chaw nitrogen ntawm qhov cua kub ntawm 5 ° C / min. Nws yog thawj zaug khaws cia ntawm qhov ntsuas kub tsis tu ncua ntawm 550 ° C rau 2h, tom qab ntawd txuas ntxiv mus txog 800 ° C thiab khaws cia ntawm qhov kub thiab txias rau 2h, thiab tom qab ntawd txias txias kom qis dua 100 ° C thiab tawm mus kom tau txais silicon-carbon. cov khoom sib xyaw.
1.2 Cov txheej txheem ua cim
Qhov loj me me ntawm cov khoom siv tau raug tshuaj xyuas los ntawm kev ntsuas particle loj (Mastersizer 2000 version, ua hauv UK). Cov hmoov uas tau txais hauv txhua kauj ruam tau raug kuaj los ntawm kev tshuaj ntsuam xyuas electron microscopy (Regulus8220, ua nyob rau hauv Nyiv) los tshuaj xyuas cov morphology thiab qhov loj ntawm cov hmoov. Cov txheej txheem theem ntawm cov khoom raug tshuaj xyuas siv lub X-ray hmoov diffraction analyzer (D8 ADVANCE, ua nyob rau hauv lub teb chaws Yelemees), thiab lub ntsiab muaj pes tsawg leeg ntawm cov khoom raug soj ntsuam siv lub zog spectrum analyzer. Cov khoom siv silicon-carbon composite tau siv los ua ib lub pob ib nrab ntawm cov qauv CR2032, thiab qhov sib piv ntawm silicon-carbon: SP: CNT: CMC: SBR yog 92: 2: 2: 1.5: 2.5. Lub txee electrode yog cov ntawv hlau lithium, cov electrolyte yog cov khoom lag luam electrolyte ( qauv 1901, ua nyob rau hauv Kauslim), Celgard 2320 diaphragm yog siv, tus nqi thiab tawm voltage ntau yog 0.005-1.5 V, tus nqi thiab tawm tam sim no yog 0.1 C. (1C = 1A), thiab qhov tso tawm tam sim no yog 0.05 C.
Txhawm rau txhawm rau tshawb xyuas qhov ua tau zoo ntawm cov khoom siv silicon-carbon sib xyaw, laminated me me mos-pob roj teeb 408595 tau ua. Qhov zoo electrode siv NCM811 (ua hauv Hunan, qib roj teeb), thiab qhov tsis zoo electrode graphite yog doped nrog 8% silicon-carbon khoom. Qhov zoo electrode slurry mis yog 96% NCM811, 1.2% polyvinylidene fluoride (PVDF), 2% conductive tus neeg saib xyuas SP, 0.8% CNT, thiab NMP yog siv los ua dispersant; Cov mis tsis zoo electrode slurry yog 96% cov khoom siv tsis zoo electrode, 1.3% CMC, 1.5% SBR 1.2% CNT, thiab dej yog siv los ua dispersant. Tom qab nplawm, txheej, dov, txiav, lamination, tab welding, ntim, ci, kua tshuaj, tsim thiab muaj peev xwm faib, 408595 laminated me me mos pob roj teeb uas muaj peev xwm ntawm 3 Ah tau npaj. Qhov kev ua tau zoo ntawm 0.2C, 0.5C, 1C, 2C thiab 3C thiab lub voj voog kev ua haujlwm ntawm 0.5C them thiab 1C tawm tau raug kuaj. Tus nqi them thiab tawm qhov hluav taws xob yog 2.8-4.2 V, qhov tam sim no thiab qhov hluav taws xob tsis tu ncua, thiab qhov txiav tawm tam sim no yog 0.5C.
2 Cov txiaj ntsig thiab kev sib tham
Thawj thawj zaug silicon hmoov tau pom los ntawm kev siv tshuab electron microscopy (SEM). Cov hmoov silicon yog irregularly granular nrog ib tug particle loj ntawm tsawg tshaj li 2μm, raws li qhia nyob rau hauv daim duab 1(a). Tom qab lub pob milling, qhov loj ntawm silicon hmoov tau txo qis mus txog 100 nm [Daim duab 1(b)]. Qhov ntsuas particle loj pom tau tias D50 ntawm silicon hmoov tom qab pob milling yog 110 nm thiab D90 yog 175 nm. Kev ua tib zoo tshuaj xyuas ntawm cov morphology ntawm silicon hmoov tom qab lub pob milling qhia cov qauv flaky (qhov tsim ntawm cov qauv flaky yuav raug txheeb xyuas ntxiv los ntawm cov hla ntu SEM tom qab). Yog li, cov ntaub ntawv D90 tau los ntawm qhov ntsuas particle loj yuav tsum yog qhov ntev ntawm nanosheet. Ua ke nrog cov txiaj ntsig SEM, nws tuaj yeem txiav txim siab tias qhov loj ntawm cov nanosheet tau yog me dua li qhov tseem ceeb ntawm 150 nm ntawm kev tawg ntawm silicon hmoov thaum them thiab tawm hauv qhov tsawg kawg nkaus ib qhov ntev. Qhov tsim ntawm lub flaky morphology feem ntau yog vim qhov sib txawv ntawm lub zog sib txawv ntawm cov dav hlau siv lead ua ntawm crystalline silicon, ntawm cov {111} dav hlau ntawm silicon muaj qis zog dissociation dua li {100} thiab {110} siv lead ua dav hlau. Yog li ntawd, lub dav hlau siv lead ua no yooj yim dua thinned los ntawm pob milling, thiab thaum kawg tsim cov qauv flaky. Cov qauv flaky yog qhov tsim nyog rau kev sib sau ntawm cov qauv xoob, tseg qhov chaw rau lub ntim nthuav dav ntawm silicon, thiab txhim kho kev ruaj ntseg ntawm cov khoom.
Cov slurry uas muaj nano-silicon, CNT thiab graphite tau txau, thiab cov hmoov ua ntej thiab tom qab txau tau tshuaj xyuas los ntawm SEM. Cov txiaj ntsig tau pom hauv daim duab 2. Cov graphite matrix ntxiv ua ntej txau yog cov qauv flake uas muaj qhov loj ntawm 5 txog 20 μm [Daim duab 2(a)]. Qhov ntsuas particle loj ntawm graphite qhia tau tias D50 yog 15μm. Cov hmoov tau txais tom qab tshuaj tsuag muaj ib tug kheej kheej morphology [Daim duab 2(b)], thiab nws yuav pom tau tias cov graphite yog coated los ntawm txheej txheej tom qab txau. D50 ntawm cov hmoov tom qab txau yog 26.2 μm. Cov yam ntxwv morphological ntawm cov khoom thib ob tau soj ntsuam los ntawm SEM, qhia cov yam ntxwv ntawm cov qauv xoob xoob uas tau sau los ntawm nanomaterials [Daim duab 2(c)]. Cov qauv ntxeem tau yog tsim los ntawm silicon nanosheets thiab CNTs intertwined nrog ib leeg [Daim duab 2(d)], thiab qhov ntsuas qhov chaw tshwj xeeb (BET) yog siab li 53.3 m2 / g. Yog li ntawd, tom qab txau, silicon nanosheets thiab CNTs nws tus kheej sib sau ua ke los tsim cov qauv ntxeem tau.
Cov txheej ntxeem tau raug kho nrog cov kua roj carbon txheej, thiab tom qab ntxiv cov pa roj carbon txheej precursor pitch thiab carbonization, SEM kev soj ntsuam tau ua tiav. Cov txiaj ntsig tau pom nyob rau hauv daim duab 3. Tom qab cov pa roj carbon pre-txheej txheej, qhov saum npoo ntawm cov khoom thib ob yuav du, nrog cov txheej txheem txheej txheej, thiab txheej txheej tiav, raws li pom hauv daim duab 3(a) thiab (b). Tom qab cov pa roj carbonization, cov txheej txheej txheej txheej tuav lub xeev txheej zoo [Daim duab 3(c)]. Tsis tas li ntawd, daim duab SEM cross-sectional qhia tau hais tias strip-shaped nanoparticles [Daim duab 3(d)], uas sib haum rau cov yam ntxwv morphological ntawm nanosheets, ntxiv txheeb xyuas qhov tsim ntawm silicon nanosheets tom qab pob milling. Tsis tas li ntawd, daim duab 3(d) qhia tau hais tias muaj cov fillers ntawm ib co nanosheets. Qhov no feem ntau yog los ntawm kev siv cov kua theem txheej txheej txheem. Cov tshuaj asphalt yuav nkag mus rau hauv cov khoom siv, kom lub ntsej muag sab hauv silicon nanosheets tau txais cov pa roj carbon txheej tiv thaiv txheej. Yog li ntawd, los ntawm kev siv cov txheej txheem ua kua, ntxiv rau kom tau txais cov nyhuv thib ob txheej txheej, cov txheej txheem ob txheej ntawm cov txheej txheem tseem tuaj yeem tau txais. Cov hmoov carbonized tau raug kuaj los ntawm BET, thiab qhov ntsuas tau yog 22.3 m2 / g.
Cov hmoov carbonized tau raug kuaj xyuas qhov sib txawv ntawm lub zog (EDS), thiab cov txiaj ntsig tau pom hauv daim duab 4(a). Cov tub ntxhais micron loj yog C tivthaiv, sib haum rau graphite matrix, thiab txheej txheej muaj silicon thiab oxygen. Txhawm rau tshawb xyuas cov qauv ntawm silicon ntxiv, kev kuaj X-ray diffraction (XRD) tau ua, thiab cov txiaj ntsig tau pom hauv daim duab 4(b). Cov khoom siv feem ntau yog tsim los ntawm graphite thiab ib leeg-crystal silicon, tsis muaj cov yam ntxwv ntawm silicon oxide, qhia tias cov pa oxygen ntawm lub zog spectrum kuaj feem ntau yog los ntawm ntuj oxidation ntawm silicon nto. Cov khoom siv silicon-carbon composite yog sau ua S1.
Cov khoom siv silicon-carbon tau npaj S1 tau raug rau cov khawm-hom ib nrab-cell ntau lawm thiab kev kuaj nqi-tso tawm. Thawj qhov kev them nyiaj-kho tawm nkhaus yog qhia hauv daim duab 5. Lub peev xwm thim rov qab yog 1000.8 mAh / g, thiab thawj lub voj voog ua haujlwm tau siab li 93.9%, uas yog siab dua thawj qhov ua tau zoo ntawm cov khoom siv silicon feem ntau yam tsis muaj pre- lithiation qhia nyob rau hauv cov ntaub ntawv. Thawj qhov ua tau zoo tshaj plaws qhia tau hais tias cov khoom siv silicon-carbon sib xyaw muaj kev ruaj ntseg siab. Txhawm rau txhawm rau txheeb xyuas qhov cuam tshuam ntawm cov qauv ntxeem tau, kev sib txuas sib txuas thiab cov pa roj carbon txheej ntawm kev ruaj ntseg ntawm cov khoom siv silicon-carbon, ob hom silicon-carbon cov ntaub ntawv tau npaj yam tsis ntxiv CNT thiab tsis muaj cov pa roj carbon txheej txheem.
Lub morphology ntawm carbonized hmoov ntawm silicon-carbon composite cov ntaub ntawv uas tsis ntxiv CNT yog qhia nyob rau hauv daim duab 6. Tom qab ua kua theem txheej thiab carbonization, txheej txheej yuav pom meej meej nyob rau saum npoo ntawm cov khoom thib ob hauv daim duab 6(a). Qhov hla-sectional SEM ntawm cov khoom siv carbonized yog pom hauv daim duab 6(b). Lub stacking ntawm silicon nanosheets muaj cov yam ntxwv ntxeem tau, thiab BET xeem yog 16.6 m2 / g. Txawm li cas los xij, piv nrog cov ntaub ntawv nrog CNT [raws li qhia hauv daim duab 3(d), BET kev sim ntawm nws cov hmoov carbonized yog 22.3 m2 / g], sab hauv nano-silicon stacking ceev yog siab dua, qhia tias qhov sib ntxiv ntawm CNT tuaj yeem txhawb nqa. tsim ntawm ib tug ntxeem tau qauv. Tsis tas li ntawd, cov khoom siv tsis muaj peb-dimensional conductive network tsim los ntawm CNT. Cov khoom siv silicon-carbon composite yog sau ua S2.
Cov yam ntxwv morphological ntawm silicon-carbon composite cov ntaub ntawv npaj los ntawm cov khoom-theem carbon txheej yog qhia nyob rau hauv daim duab 7. Tom qab carbonization, muaj ib tug pom tseeb txheej txheej nyob rau saum npoo, raws li qhia nyob rau hauv daim duab 7(a). Daim duab 7(b) qhia tau hais tias muaj strip-zoo li tus nanoparticles nyob rau hauv tus ntoo khaub lig seem, uas sib haum mus rau lub morphological yam ntxwv ntawm nanosheets. Kev sib sau ntawm nanosheets tsim cov qauv ntxeem tau. Tsis muaj qhov pom tseeb muab tso rau saum npoo ntawm cov nanosheets sab hauv, qhia tias cov khoom siv-theem carbon txheej tsuas yog tsim cov txheej txheej carbon nrog cov qauv ntxeem tau, thiab tsis muaj txheej txheej sab hauv rau silicon nanosheets. Cov khoom siv silicon-carbon composite no tau sau ua S3.
Lub pob-hom ib nrab-cell nqi thiab kev kuaj tawm tau ua tiav ntawm S2 thiab S3. Lub peev xwm tshwj xeeb thiab thawj qhov ua tau zoo ntawm S2 yog 1120.2 mAh / g thiab 84.8%, feem, thiab lub peev xwm tshwj xeeb thiab thawj qhov ua tau zoo ntawm S3 yog 882.5 mAh / g thiab 82.9%, feem. Lub peev xwm tshwj xeeb thiab thawj qhov ua tau zoo ntawm cov khoom siv-theem coated S3 qauv yog qhov qis tshaj plaws, qhia tias tsuas yog cov pa roj carbon txheej ntawm cov txheej txheem ntxeem tau ua tiav, thiab cov pa roj carbon txheej ntawm sab hauv silicon nanosheets tsis tau ua, uas tsis tuaj yeem muab kev ua si tag nrho. mus rau lub peev xwm tshwj xeeb ntawm cov khoom siv silicon thiab tsis tuaj yeem tiv thaiv qhov chaw ntawm cov khoom siv silicon. Thawj qhov ua tau zoo ntawm cov qauv S2 yam tsis muaj CNT kuj tseem qis dua li ntawm cov khoom siv silicon-carbon composite uas muaj CNT, qhia tias nyob rau hauv lub hauv paus ntawm txheej txheej zoo, cov khoom siv hluav taws xob thiab qib siab dua ntawm cov qauv ntxeem tau zoo rau kev txhim kho. ntawm tus nqi thiab tso tawm efficiency ntawm cov khoom siv silicon-carbon.
Cov khoom siv silicon-carbon S1 tau siv los ua lub pob me me uas muaj roj teeb puv los tshuaj xyuas qhov kev ua tau zoo thiab lub voj voog kev ua haujlwm. Txoj kev tawm tus nqi nkhaus yog qhia hauv daim duab 8(a). Lub peev xwm tawm ntawm 0.2C, 0.5C, 1C, 2C thiab 3C yog 2.970, 2.999, 2.920, 2.176 thiab 1.021 Ah, feem. 1C tso tawm tus nqi yog siab li 98.3%, tab sis 2C paug tus nqi poob mus rau 73.3%, thiab 3C paug tus nqi poob ntxiv mus rau 34.4%. Txhawm rau koom nrog silicon tsis zoo electrode pauv pawg, thov ntxiv WeChat: shimobang. Nyob rau hauv cov nqe lus ntawm kev them nqi, 0.2C, 0.5C, 1C, 2C thiab 3C them peev xwm yog 3.186, 3.182, 3.081, 2.686 thiab 2.289 Ah, feem. 1C them tus nqi yog 96.7%, thiab 2C them tus nqi tseem nce mus txog 84.3%. Txawm li cas los xij, soj ntsuam qhov kev them nyiaj nkhaus hauv daim duab 8(b), 2C them lub platform yog qhov loj dua li 1C them lub platform, thiab nws qhov kev them nyiaj tsis tu ncua rau feem ntau (55%), qhia tias polarization ntawm 2C rechargeable roj teeb yog xa loj heev. Cov khoom siv silicon-carbon muaj kev them nyiaj zoo thiab kev ua haujlwm tawm ntawm 1C, tab sis cov yam ntxwv ntawm cov khoom yuav tsum tau txhim kho ntxiv kom ua tiav qhov kev ua tau zoo dua. Raws li pom hauv daim duab 9, tom qab 450 lub voj voog, lub peev xwm tuav tau yog 78%, uas qhia txog kev ua haujlwm zoo.
Qhov saum npoo ntawm lub electrode ua ntej thiab tom qab lub voj voog tau tshawb xyuas los ntawm SEM, thiab cov txiaj ntsig tau pom hauv daim duab 10. Ua ntej lub voj voog, cov ntaub ntawv ntawm cov graphite thiab silicon-carbon yog qhov tseeb [Daim duab 10(a)]; Tom qab lub voj voog, txheej txheej txheej yog pom tseeb tsim tawm ntawm qhov chaw [Daim duab 10(b)], uas yog cov yeeb yaj kiab SEI tuab. SEI zaj duab xis roughnessThe active lithium noj yog siab, uas tsis conducive rau lub voj voog kev ua tau zoo. Yog li ntawd, txhawb kev tsim cov yeeb yaj kiab SEI du (xws li kev tsim kho SEI zaj duab xis, ntxiv cov khoom siv hluav taws xob tsim nyog, thiab lwm yam) tuaj yeem txhim kho lub voj voog kev ua haujlwm. Kev soj ntsuam ntawm SEM hla ntu ntawm silicon-carbon hais tom qab lub voj voog [Daim duab 10(c)] qhia tau hais tias tus thawj strip-shaped silicon nanoparticles tau dhau los ua coarser thiab cov qauv ntxeem tau raug tshem tawm. Qhov no feem ntau yog vim qhov nruam ntim expansion thiab contraction ntawm cov khoom siv silicon-carbon thaum lub voj voog. Yog li ntawd, cov qauv ntxeem tau yuav tsum tau txhim kho ntxiv kom muaj qhov chaw tsis txaus rau qhov ntim nthuav dav ntawm cov khoom siv silicon.
3 Kev xaus
Raws li lub ntim expansion, tsis zoo conductivity thiab tsis zoo interface stability ntawm silicon-raws li tsis zoo electrode cov ntaub ntawv, daim ntawv no ua rau lub hom phiaj kev txhim kho, los ntawm lub morphology shaping ntawm silicon nanosheets, ntxeem tau qauv tsim, conductive network tsim thiab ua tiav cov pa roj carbon txheej ntawm tag nrho cov theem nrab particles. , txhawm rau txhim kho kev ruaj ntseg ntawm silicon-raws li cov khoom tsis zoo electrode tag nrho. Kev sib sau ntawm silicon nanosheets tuaj yeem tsim cov qauv ntxeem tau. Kev taw qhia ntawm CNT yuav txhawb ntxiv tsim cov qauv ntxeem tau. Cov khoom siv silicon-carbon composite npaj los ntawm cov kua theem txheej muaj ob txheej txheej carbon ntau tshaj qhov uas tau npaj los ntawm cov txheej txheem txheej, thiab nthuav tawm ntau dua qhov tshwj xeeb thiab thawj qhov ua tau zoo. Tsis tas li ntawd, thawj qhov ua tau zoo ntawm cov khoom siv silicon-carbon composite uas muaj CNT yog siab dua qhov uas tsis muaj CNT, uas yog vim qhov siab dua ntawm cov qauv porous lub peev xwm los txo qhov ntim ntawm cov khoom siv silicon. Kev taw qhia ntawm CNT yuav tsim ib qho kev sib txuas ntawm peb-dimensional conductive, txhim kho cov conductivity ntawm silicon-raws li cov ntaub ntawv, thiab qhia tus nqi zoo ntawm 1C; thiab cov ntaub ntawv qhia txog kev ua haujlwm zoo. Txawm li cas los xij, cov qauv ntxeem tau ntawm cov khoom siv yuav tsum tau ntxiv dag zog los muab qhov chaw tsis txaus rau lub ntim nthuav dav ntawm silicon, thiab txhawb kev tsim ntawm tus du.thiab ntom SEI zaj duab xis los txhim kho lub voj voog kev ua haujlwm ntawm cov khoom siv silicon-carbon composite.
Peb kuj muab high-purity graphite thiab silicon carbide khoom, uas dav siv nyob rau hauv wafer ua xws li oxidation, diffusion, thiab annealing.
Txais tos txhua tus neeg muas zaub los ntawm thoob plaws lub ntiaj teb tuaj xyuas peb rau kev sib tham ntxiv!
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Post lub sij hawm: Nov-13-2024