Cov roj teeb lithium-ion feem ntau yog tsim los ntawm kev siv zog ntau. Thaum sov chav, cov khoom siv electrode tsis zoo uas siv silicon sib xyaw nrog lithium los tsim cov khoom lithium-nplua nuj Li3.75Si theem, nrog lub peev xwm tshwj xeeb txog li 3572 mAh / g, uas siab dua li lub peev xwm tshwj xeeb theoretical ntawm graphite negative electrode 372 mAh / g. Txawm li cas los xij, thaum lub sijhawm rov them thiab tso tawm ntawm cov khoom siv electrode tsis zoo uas siv silicon, kev hloov pauv theem ntawm Si thiab Li3.75Si tuaj yeem tsim cov ntim loj heev (kwv yees li 300%), uas yuav ua rau cov hmoov av ntawm cov khoom siv electrode thiab kev tsim cov yeeb yaj kiab SEI tas mus li, thiab thaum kawg ua rau lub peev xwm poob sai. Kev lag luam feem ntau txhim kho kev ua tau zoo ntawm cov khoom siv electrode tsis zoo uas siv silicon thiab kev ruaj khov ntawm cov roj teeb silicon los ntawm nano-sizing, carbon coating, pore tsim thiab lwm yam thev naus laus zis.
Cov ntaub ntawv carbon muaj cov conductivity zoo, pheej yig, thiab dav qhov chaw. Lawv tuaj yeem txhim kho qhov conductivity thiab qhov ruaj khov ntawm cov ntaub ntawv silicon. Lawv feem ntau yog siv ua cov khoom siv txhim kho kev ua tau zoo rau cov electrodes tsis zoo silicon. Cov ntaub ntawv silicon-carbon yog cov kev taw qhia tseem ceeb ntawm cov electrodes tsis zoo silicon. Cov txheej txheem carbon tuaj yeem txhim kho qhov ruaj khov ntawm cov ntaub ntawv silicon, tab sis nws lub peev xwm los tiv thaiv kev nthuav dav ntawm silicon yog dav dav thiab tsis tuaj yeem daws qhov teeb meem ntawm kev nthuav dav ntawm silicon. Yog li ntawd, txhawm rau txhim kho qhov ruaj khov ntawm cov ntaub ntawv silicon, cov qauv porous yuav tsum tau tsim. Kev sib tsoo pob yog ib txoj hauv kev lag luam rau kev npaj cov ntaub ntawv nano. Cov khoom ntxiv sib txawv lossis cov khoom siv tuaj yeem ntxiv rau cov slurry tau los ntawm kev sib tsoo pob raws li qhov xav tau tsim ntawm cov khoom sib xyaw. Cov slurry yog sib npaug los ntawm ntau yam slurries thiab tsuag-qhuav. Thaum lub sijhawm ziab tam sim ntawd, cov nanoparticles thiab lwm yam khoom hauv cov slurry yuav tsim cov yam ntxwv porous. Daim ntawv no siv cov khoom lag luam thiab ib puag ncig zoo milling pob thiab tshuaj tsuag tshuab ziab los npaj cov ntaub ntawv porous silicon.
Kev ua tau zoo ntawm cov ntaub ntawv silicon-based kuj tseem tuaj yeem txhim kho los ntawm kev tswj hwm cov morphology thiab kev faib tawm ntawm silicon nanomaterials. Tam sim no, cov ntaub ntawv silicon-based nrog ntau yam morphology thiab kev faib tawm tau npaj, xws li silicon nanorods, porous graphite embedded nanosilicon, nanosilicon faib rau hauv carbon spheres, silicon / graphene array porous qauv, thiab lwm yam. Ntawm tib qhov ntsuas, piv nrog nanoparticles, nanosheets tuaj yeem txo qhov teeb meem crushing los ntawm kev nthuav dav ntim, thiab cov khoom muaj qhov ceev compaction siab dua. Kev sib sau ua ke ntawm nanosheets kuj tseem tuaj yeem tsim cov qauv porous. Koom nrog silicon negative electrode pauv pawg. Muab qhov chaw buffer rau qhov ntim nthuav dav ntawm cov ntaub ntawv silicon. Kev qhia txog carbon nanotubes (CNTs) tsis tuaj yeem tsuas yog txhim kho qhov conductivity ntawm cov khoom siv, tab sis kuj txhawb kev tsim cov qauv porous ntawm cov khoom siv vim nws cov yam ntxwv morphological ib-dimensional. Tsis muaj kev tshaj tawm txog cov qauv porous tsim los ntawm silicon nanosheets thiab CNTs. Daim ntawv no siv cov pob zeb milling, sib tsoo thiab dispersion uas siv tau hauv kev lag luam, tshuaj tsuag kom qhuav, carbon pre-coating thiab calcination methods, thiab qhia txog cov porous promoters hauv cov txheej txheem npaj los npaj cov khoom siv electrode tsis zoo uas tsim los ntawm kev sib sau ua ke ntawm silicon nanosheets thiab CNTs. Cov txheej txheem npaj yog yooj yim, zoo rau ib puag ncig, thiab tsis muaj cov kua pov tseg lossis cov khib nyiab pov tseg. Muaj ntau cov ntawv qhia txog kev txheej carbon ntawm cov ntaub ntawv silicon, tab sis muaj ob peb qhov kev sib tham tob txog cov nyhuv ntawm kev txheej. Daim ntawv no siv asphalt ua cov pa roj carbon los tshawb nrhiav cov nyhuv ntawm ob txoj kev txheej carbon, txheej kua theem thiab txheej khoom theem, ntawm cov nyhuv txheej thiab kev ua haujlwm ntawm cov ntaub ntawv electrode tsis zoo uas ua los ntawm silicon.
1 Kev Sim
1.1 Kev npaj khoom siv
Kev npaj cov khoom siv sib xyaw ua ke silicon-carbon feem ntau muaj tsib kauj ruam: kev sib tsoo pob, kev sib tsoo thiab kev sib cais, kev ziab tshuaj tsuag, kev txheej ua ntej carbon thiab kev ua kom carbonization. Ua ntej, hnyav 500 g ntawm cov hmoov silicon pib (hauv tebchaws, 99.99% purity), ntxiv 2000 g ntawm isopropanol, thiab ua kev sib tsoo pob ntub ntawm qhov ceev ntawm kev sib tsoo pob ntawm 2000 r / min rau 24 teev kom tau txais nano-scale silicon slurry. Cov silicon slurry tau txais raug xa mus rau lub tank hloov pauv dispersion, thiab cov ntaub ntawv raug ntxiv raws li qhov sib piv ntawm silicon: graphite (tsim nyob rau hauv Shanghai, qib roj teeb): carbon nanotubes (tsim nyob rau hauv Tianjin, qib roj teeb): polyvinyl pyrrolidone (tsim nyob rau hauv Tianjin, qib analytical) = 40: 60: 1.5: 2. Isopropanol yog siv los kho cov ntsiab lus khov, thiab cov ntsiab lus khov yog tsim los ua 15%. Kev sib tsoo thiab kev sib cais yog ua tiav ntawm qhov ceev ntawm kev sib cais ntawm 3500 r / min rau 4 teev. Lwm pawg ntawm cov slurries tsis ntxiv CNTs raug piv, thiab lwm cov ntaub ntawv zoo ib yam. Cov slurry dispersed tau txais ces raug xa mus rau lub tank pub kom qhuav, thiab kev ziab tsuag yog ua tiav hauv huab cua tiv thaiv nitrogen, nrog rau qhov kub thiab txias ntawm qhov nkag thiab qhov tawm yog 180 thiab 90 ° C, feem. Tom qab ntawd ob hom carbon txheej tau piv, txheej txheej khoom thiab txheej kua. Txoj kev txheej txheej khoom yog: cov hmoov qhuav tsuag yog sib xyaw nrog 20% asphalt hmoov (ua nyob rau hauv Kauslim Teb, D50 yog 5 μm), sib xyaw rau hauv lub tshuab sib tov rau 10 feeb, thiab qhov ceev sib tov yog 2000 r / min kom tau txais cov hmoov ua ntej coated. Txoj kev txheej txheej kua yog: cov hmoov qhuav tsuag yog ntxiv rau cov kua xylene (ua nyob rau hauv Tianjin, qib analytical) uas muaj 20% asphalt yaj hauv cov hmoov ntawm cov khoom khov ntawm 55%, thiab nqus tsev sib tov sib npaug. Ci hauv lub qhov cub nqus tsev ntawm 85 ℃ rau 4 teev, muab tso rau hauv lub tshuab sib tov rau kev sib tov, qhov ceev sib tov yog 2000 r / min, thiab lub sijhawm sib tov yog 10 feeb kom tau txais cov hmoov ua ntej coated. Thaum kawg, cov hmoov ua ntej coated tau calcined hauv lub qhov cub rotary hauv qab huab cua nitrogen ntawm qhov kub ntawm 5 ° C / feeb. Nws tau khaws cia ua ntej ntawm qhov kub tas li ntawm 550 ° C rau 2 teev, tom qab ntawd txuas ntxiv mus rau cua sov txog 800 ° C thiab khaws cia ntawm qhov kub tas li rau 2 teev, thiab tom qab ntawd txias ntuj kom qis dua 100 ° C thiab tso tawm kom tau txais cov khoom siv silicon-carbon composite.
1.2 Cov txheej txheem piav qhia txog tus cwj pwm
Kev faib tawm ntawm cov khoom me me ntawm cov khoom siv tau raug tshuaj xyuas siv lub tshuab ntsuas qhov loj me ntawm cov khoom me me (Mastersizer 2000 version, ua nyob rau hauv UK). Cov hmoov uas tau txais hauv txhua kauj ruam tau raug kuaj los ntawm kev ntsuas hluav taws xob microscopy (Regulus8220, ua nyob rau hauv Nyiv) los tshuaj xyuas cov morphology thiab qhov loj ntawm cov hmoov. Cov qauv theem ntawm cov khoom siv tau raug tshuaj xyuas siv lub tshuab ntsuas X-ray hmoov diffraction (D8 ADVANCE, ua nyob rau hauv lub teb chaws Yelemees), thiab cov khoom sib xyaw ntawm cov khoom siv tau raug tshuaj xyuas siv lub tshuab ntsuas hluav taws xob. Cov khoom siv silicon-carbon composite tau txais tau siv los ua lub pob ib nrab-cell ntawm tus qauv CR2032, thiab qhov sib piv ntawm silicon-carbon: SP: CNT: CMC: SBR yog 92: 2: 2: 1.5: 2.5. Lub electrode counter yog ib daim ntawv hlau lithium, lub electrolyte yog ib lub electrolyte lag luam (qauv 1901, ua nyob rau hauv Kauslim Teb), siv Celgard 2320 diaphragm, qhov voltage ntawm charge thiab discharge yog 0.005-1.5 V, qhov tam sim no charge thiab discharge yog 0.1 C (1C = 1A), thiab qhov tam sim no discharge cut-off yog 0.05 C.
Yuav kom tshawb nrhiav ntxiv txog kev ua tau zoo ntawm cov khoom siv sib xyaw silicon-carbon, lub roj teeb me me uas tau ua los ntawm cov khoom siv laminated 408595 tau ua tiav. Lub electrode zoo siv NCM811 (ua nyob rau hauv Hunan, qib roj teeb), thiab lub electrode graphite tsis zoo yog doped nrog 8% silicon-carbon khoom. Cov mis slurry electrode zoo yog 96% NCM811, 1.2% polyvinylidene fluoride (PVDF), 2% conductive agent SP, 0.8% CNT, thiab NMP yog siv ua dispersant; cov mis slurry electrode tsis zoo yog 96% cov khoom siv sib xyaw tsis zoo electrode, 1.3% CMC, 1.5% SBR 1.2% CNT, thiab dej yog siv ua dispersant. Tom qab do, txheej, dov, txiav, lamination, tab vuam, ntim khoom, ci, kua txhaj tshuaj, tsim thiab faib peev xwm, 408595 laminated me me pob roj teeb nrog lub peev xwm ntsuas ntawm 3 Ah tau npaj. Cov kev ua tau zoo ntawm 0.2C, 0.5C, 1C, 2C thiab 3C thiab kev ua tau zoo ntawm 0.5C them thiab 1C tso tawm tau raug sim. Qhov ntau ntawm qhov them thiab tso tawm voltage yog 2.8-4.2 V, tam sim no tas li thiab qhov hluav taws xob tas li them, thiab tam sim no txiav tawm yog 0.5C.
2 Cov Txiaj Ntsig thiab Kev Sib Tham
Cov hmoov silicon thawj zaug tau pom los ntawm kev siv lub tshuab ntsuas hluav taws xob (SEM). Cov hmoov silicon yog cov hmoov tsis sib xws nrog qhov loj me me dua 2μm, raws li pom hauv Daim Duab 1 (a). Tom qab pob milling, qhov loj me ntawm cov hmoov silicon tau txo qis mus txog li 100 nm [Daim Duab 1 (b)]. Kev sim qhov loj me ntawm cov hmoov silicon tau qhia tias D50 ntawm cov hmoov silicon tom qab pob milling yog 110 nm thiab D90 yog 175 nm. Kev tshuaj xyuas zoo ntawm cov qauv ntawm cov hmoov silicon tom qab pob milling qhia txog cov qauv flaky (kev tsim ntawm cov qauv flaky yuav raug txheeb xyuas ntxiv los ntawm SEM cross-sectional tom qab). Yog li ntawd, cov ntaub ntawv D90 tau los ntawm kev sim qhov loj me ntawm cov khoom yuav tsum yog qhov ntev ntawm nanosheet. Ua ke nrog cov txiaj ntsig SEM, nws tuaj yeem txiav txim siab tias qhov loj me ntawm cov nanosheet tau txais yog me dua qhov tseem ceeb ntawm 150 nm ntawm kev tawg ntawm cov hmoov silicon thaum lub sijhawm them thiab tso tawm hauv tsawg kawg ib qho. Qhov kev tsim cov qauv flaky yog vim muaj ntau yam sib txawv ntawm cov dav hlau siv lead ua ntawm crystalline silicon, ntawm cov uas {111} dav hlau ntawm silicon muaj zog dissociation qis dua li {100} thiab {110} dav hlau siv lead ua. Yog li ntawd, cov dav hlau siv lead ua no yooj yim dua los ntawm kev sib tsoo pob, thiab thaum kawg tsim cov qauv flaky. Cov qauv flaky yog qhov zoo rau kev sib sau ua ke ntawm cov qauv xoob, khaws qhov chaw rau qhov ntim nthuav dav ntawm silicon, thiab txhim kho kev ruaj khov ntawm cov khoom siv.
Cov slurry uas muaj nano-silicon, CNT thiab graphite tau raug txau, thiab cov hmoov ua ntej thiab tom qab txau tau raug tshuaj xyuas los ntawm SEM. Cov txiaj ntsig tau pom hauv Daim Duab 2. Lub graphite matrix ntxiv ua ntej txau yog cov qauv flake ib txwm muaj nrog qhov loj ntawm 5 txog 20 μm [Daim Duab 2 (a)]. Qhov kev xeem faib qhov loj me ntawm graphite qhia tau tias D50 yog 15μm. Cov hmoov tau txais tom qab txau muaj lub cev kheej kheej [Daim Duab 2 (b)], thiab nws tuaj yeem pom tias graphite tau 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 me me thib ob tau pom los ntawm SEM, qhia txog cov yam ntxwv ntawm cov qauv xoob porous sau los ntawm nanomaterials [Daim Duab 2 (c)]. Cov qauv porous yog tsim los ntawm silicon nanosheets thiab CNTs intertwined nrog ib leeg [Daim Duab 2 (d)], thiab qhov kev xeem tshwj xeeb nto cheeb tsam (BET) yog siab txog 53.3 m2 / g. Yog li ntawd, tom qab txau, silicon nanosheets thiab CNTs sib sau ua ke los ua ib qho qauv porous.
Cov txheej porous tau kho nrog cov kua 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 hauv Daim Duab 3. Tom qab carbon pre-coating, qhov chaw ntawm cov khoom me me thib ob ua du, nrog rau cov txheej txheej pom tseeb, thiab cov txheej txheej tiav, raws li pom hauv Daim Duab 3 (a) thiab (b). Tom qab carbonization, cov txheej txheej saum npoo tswj hwm lub xeev txheej zoo [Daim Duab 3 (c)]. Tsis tas li ntawd, daim duab SEM cross-sectional qhia cov nanoparticles zoo li strip [Daim Duab 3 (d)], uas sib raug rau cov yam ntxwv morphological ntawm nanosheets, ntxiv xyuas qhov tsim ntawm silicon nanosheets tom qab pob milling. Tsis tas li ntawd, Daim Duab 3 (d) qhia tias muaj cov khoom sau ntawm qee cov nanosheets. Qhov no feem ntau yog vim siv cov txheej txheem kua theem txheej. Cov kua asphalt yuav nkag mus rau hauv cov khoom, yog li ntawd qhov chaw ntawm sab hauv silicon nanosheets tau txais cov txheej txheej tiv thaiv carbon txheej. Yog li ntawd, los ntawm kev siv cov kua txheej, ntxiv rau kev tau txais cov nyhuv txheej txheej thib ob, cov nyhuv txheej txheej ob npaug ntawm cov txheej txheej thawj zaug kuj tuaj yeem tau txais. Cov hmoov carbonized tau sim los ntawm BET, thiab qhov tshwm sim ntawm kev xeem yog 22.3 m2 / g.
Cov hmoov carbonized tau raug rau kev tshuaj xyuas lub zog spectrum cross-sectional (EDS), thiab cov txiaj ntsig tau pom hauv Daim Duab 4 (a). Lub plawv micron-sized yog C Cheebtsam, sib raug rau graphite matrix, thiab txheej sab nraud muaj silicon thiab oxygen. Txhawm rau tshawb nrhiav ntxiv txog cov qauv ntawm silicon, kev sim X-ray diffraction (XRD) tau ua tiav, 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 silicon oxide pom tseeb, qhia tias cov khoom siv oxygen ntawm kev sim lub zog spectrum feem ntau los ntawm kev oxidation ntuj ntawm qhov chaw silicon. Cov khoom siv silicon-carbon composite tau kaw ua S1.
Cov khoom siv silicon-carbon S1 uas tau npaj tseg tau raug rau kev tsim ib nrab ntawm lub hlwb thiab kev sim them-tso tawm. Qhov nkhaus them-tso tawm thawj zaug tau qhia hauv Daim Duab 5. Lub peev xwm tshwj xeeb rov qab tau yog 1000.8 mAh / g, thiab thawj lub voj voog ua haujlwm tau siab txog 93.9%, uas yog siab dua li thawj qhov ua haujlwm ntawm feem ntau cov khoom siv silicon uas tsis muaj kev ua ntej lithiation tau tshaj tawm hauv cov ntaub ntawv. Qhov ua haujlwm thawj zaug siab qhia tau tias cov khoom siv silicon-carbon composite uas tau npaj tseg muaj kev ruaj khov siab. Txhawm rau txheeb xyuas cov teebmeem ntawm cov qauv porous, conductive network thiab carbon txheej rau kev ruaj khov ntawm cov khoom siv silicon-carbon, ob hom khoom siv silicon-carbon tau npaj yam tsis ntxiv CNT thiab tsis muaj thawj carbon txheej.
Cov morphology ntawm cov hmoov carbonized ntawm cov khoom siv silicon-carbon composite yam tsis ntxiv CNT tau qhia hauv Daim Duab 6. Tom qab cov kua theem txheej thiab carbonization, ib txheej txheej tuaj yeem pom tseeb ntawm qhov chaw ntawm cov khoom me me hauv Daim Duab 6 (a). SEM hla-sectional ntawm cov khoom siv carbonized tau qhia hauv Daim Duab 6 (b). Kev sib sau ua ke ntawm silicon nanosheets muaj cov yam ntxwv porous, thiab qhov kev xeem BET yog 16.6 m2 / g. Txawm li cas los xij, piv nrog cov ntaub ntawv nrog CNT [raws li tau qhia hauv Daim Duab 3 (d), qhov kev xeem BET ntawm nws cov hmoov carbonized yog 22.3 m2 / g], qhov ceev ntawm nano-silicon sab hauv yog siab dua, qhia tias kev ntxiv ntawm CNT tuaj yeem txhawb kev tsim cov qauv porous. Tsis tas li ntawd, cov khoom siv tsis muaj lub network conductive peb-seem tsim los ntawm CNT. Cov khoom siv silicon-carbon composite tau sau tseg ua S2.
Cov yam ntxwv morphological ntawm cov khoom siv silicon-carbon composite uas npaj los ntawm cov txheej txheem carbon-theem khov kho tau qhia hauv Daim Duab 7. Tom qab carbonization, muaj ib txheej txheej pom tseeb ntawm qhov chaw, raws li tau qhia hauv Daim Duab 7 (a). Daim Duab 7 (b) qhia tau hais tias muaj cov nanoparticles zoo li strip-puab hauv seem hla, uas sib raug rau cov yam ntxwv morphological ntawm nanosheets. Kev sib sau ua ke ntawm nanosheets tsim cov qauv porous. Tsis muaj qhov sau pom tseeb ntawm qhov chaw ntawm cov nanosheets sab hauv, qhia tias cov txheej txheem carbon-theem khov kho tsuas yog tsim cov txheej txheej carbon nrog cov qauv porous, thiab tsis muaj txheej txheej sab hauv rau cov nanosheets silicon. Cov khoom siv silicon-carbon composite no tau sau tseg ua S3.
Qhov kev sim them thiab tso tawm ib nrab ntawm lub pob khawm tau ua rau S2 thiab S3. Lub peev xwm tshwj xeeb thiab thawj qhov ua tau zoo ntawm S2 yog 1120.2 mAh / g thiab 84.8%, raws li, thiab lub peev xwm tshwj xeeb thiab thawj qhov ua tau zoo ntawm S3 yog 882.5 mAh / g thiab 82.9%, raws li. Lub peev xwm tshwj xeeb thiab thawj qhov ua tau zoo ntawm cov qauv S3 uas tau txheej txheem khov kho yog qhov qis tshaj plaws, qhia tias tsuas yog cov txheej txheem carbon ntawm cov qauv porous tau ua tiav, thiab cov txheej txheem carbon ntawm cov nanosheets sab hauv silicon tsis tau ua tiav, uas tsis tuaj yeem muab kev ua si tag nrho rau lub peev xwm tshwj xeeb ntawm cov khoom siv silicon thiab tsis tuaj yeem tiv thaiv qhov chaw ntawm cov khoom siv silicon. Qhov ua tau zoo thawj zaug ntawm cov qauv S2 tsis muaj CNT kuj qis dua li ntawm cov khoom siv silicon-carbon composite uas muaj CNT, qhia tias ntawm lub hauv paus ntawm cov txheej txheem zoo, lub network conductive thiab qib siab dua ntawm cov qauv porous yog qhov zoo rau kev txhim kho qhov ua tau zoo ntawm cov khoom siv silicon-carbon.
Cov khoom siv S1 silicon-carbon tau siv los ua lub roj teeb me me uas muaj cov khoom mos mos los tshuaj xyuas qhov ua tau zoo ntawm tus nqi thiab kev ua haujlwm ntawm lub voj voog. Cov kab nkhaus ntawm qhov tso tawm tau pom hauv Daim Duab 8 (a). Lub peev xwm tso tawm ntawm 0.2C, 0.5C, 1C, 2C thiab 3C yog 2.970, 2.999, 2.920, 2.176 thiab 1.021 Ah, raws li. Qhov tso tawm ntawm 1C yog siab txog 98.3%, tab sis qhov tso tawm ntawm 2C poob qis mus rau 73.3%, thiab qhov tso tawm ntawm 3C poob qis ntxiv mus rau 34.4%. Txhawm rau koom nrog pawg pauv hluav taws xob silicon tsis zoo, thov ntxiv WeChat: shimobang. Hais txog qhov them nqi, qhov them nqi ntawm 0.2C, 0.5C, 1C, 2C thiab 3C yog 3.186, 3.182, 3.081, 2.686 thiab 2.289 Ah, raws li. Tus nqi them 1C yog 96.7%, thiab tus nqi them 2C tseem ncav cuag 84.3%. Txawm li cas los xij, kev soj ntsuam cov kab them hauv Daim Duab 8 (b), lub platform them 2C loj dua li lub platform them 1C, thiab nws lub peev xwm them hluav taws xob tas li feem ntau (55%), qhia tias qhov polarization ntawm lub roj teeb rechargeable 2C twb loj heev lawm. Cov khoom siv silicon-carbon muaj kev them thiab tso tawm zoo ntawm 1C, tab sis cov yam ntxwv ntawm cov khoom siv 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, tus nqi khaws cia peev xwm yog 78%, qhia txog kev ua tau zoo ntawm lub voj voog.
Lub xeev ntawm qhov 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, qhov chaw ntawm cov ntaub ntawv graphite thiab silicon-carbon yog qhov tseeb [Daim Duab 10 (a)]; tom qab lub voj voog, ib txheej txheej yog pom tseeb tsim rau ntawm qhov chaw [Daim Duab 10 (b)], uas yog ib zaj duab xis SEI tuab. SEI zaj duab xis roughnessQhov kev siv lithium nquag yog siab, uas tsis zoo rau kev ua haujlwm ntawm lub voj voog. Yog li ntawd, kev txhawb nqa kev tsim ntawm ib zaj duab xis SEI du (xws li kev tsim cov yeeb yaj kiab SEI dag, ntxiv cov khoom siv electrolyte tsim nyog, thiab lwm yam) tuaj yeem txhim kho kev ua haujlwm ntawm lub voj voog. Kev soj ntsuam SEM hla-sectional ntawm cov khoom me me silicon-carbon tom qab lub voj voog [Daim Duab 10 (c)] qhia tau hais tias cov nanoparticles silicon zoo li daim kab xev qub tau dhau los ua coarser thiab cov qauv porous tau raug tshem tawm. Qhov no yog vim qhov ntim txuas ntxiv thiab kev cog lus ntawm cov khoom siv silicon-carbon thaum lub voj voog. Yog li ntawd, cov qauv porous yuav tsum tau txhim kho ntxiv kom muab qhov chaw buffer txaus rau qhov ntim nthuav dav ntawm cov khoom siv silicon.
3 Xaus Lus
Raws li qhov ntim nthuav dav, kev coj ua tsis zoo thiab kev ruaj khov ntawm cov khoom siv hluav taws xob tsis zoo uas siv silicon, daim ntawv no ua rau muaj kev txhim kho tshwj xeeb, los ntawm kev tsim cov duab ntawm silicon nanosheets, kev tsim cov qauv porous, kev tsim cov network conductive thiab kev txheej carbon tag nrho ntawm tag nrho cov khoom me me, los txhim kho kev ruaj khov ntawm cov khoom siv hluav taws xob tsis zoo uas siv silicon tag nrho. Kev sib sau ua ke ntawm silicon nanosheets tuaj yeem tsim cov qauv porous. Kev qhia txog CNT yuav txhawb nqa kev tsim cov qauv porous. Cov khoom siv sib xyaw silicon-carbon uas npaj los ntawm cov txheej txheej kua muaj cov nyhuv txheej carbon ob npaug dua li cov uas npaj los ntawm cov txheej txheej khoom khov, thiab muaj peev xwm tshwj xeeb dua thiab ua haujlwm tau zoo dua. Tsis tas li ntawd, qhov ua haujlwm tau zoo thawj zaug ntawm cov khoom siv sib xyaw silicon-carbon uas muaj CNT siab dua li tsis muaj CNT, uas yog vim muaj qib siab dua ntawm cov qauv porous muaj peev xwm los txo qhov ntim nthuav dav ntawm cov khoom siv silicon. Kev qhia txog CNT yuav tsim cov network conductive peb-seem, txhim kho kev coj ua ntawm cov khoom siv silicon, thiab qhia txog kev ua tau zoo ntawm 1C; thiab cov khoom siv qhia txog kev ua haujlwm zoo ntawm lub voj voog. Txawm li cas los xij, cov qauv porous ntawm cov khoom siv yuav tsum tau ua kom muaj zog ntxiv kom muab qhov chaw buffer txaus rau qhov ntim nthuav dav ntawm silicon, thiab txhawb kev tsim ntawm duthiab zaj duab xis SEI ntom ntom kom txhim kho kev ua haujlwm ntawm cov khoom siv silicon-carbon composite ntxiv.
Peb kuj muab cov khoom siv graphite thiab silicon carbide uas muaj cov khoom purity siab, uas siv dav hauv kev ua wafer xws li oxidation, diffusion, thiab annealing.
Txais tos cov neeg siv khoom los ntawm thoob plaws lub ntiaj teb tuaj xyuas peb rau kev sib tham ntxiv!
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Lub sijhawm tshaj tawm: Kaum Ib Hlis-13-2024