Mabatire a Lithium-ion akukula kwambiri m'njira yamphamvu kwambiri. Pa kutentha kwa chipinda, zinthu za electrode yochokera ku silicon zimasakanikirana ndi lithiamu kuti zipange gawo la Li3.75Si lolemera mu lithiamu, lomwe limakhala ndi mphamvu yokwana 3572 mAh/g, yomwe ndi yayikulu kwambiri kuposa mphamvu yeniyeni ya graphite negative electrode 372 mAh/g. Komabe, panthawi yobwerezabwereza kuyitanitsa ndi kutulutsa zinthu za electrode yochokera ku silicon, kusintha kwa gawo la Si ndi Li3.75Si kumatha kupanga kukula kwakukulu (pafupifupi 300%), zomwe zingayambitse kupangika kwa electrode ndi kupangika kosalekeza kwa filimu ya SEI, ndipo pamapeto pake zimapangitsa kuti mphamvuyo itsike mwachangu. Makampaniwa makamaka amawongolera magwiridwe antchito a zinthu za electrode yochokera ku silicon komanso kukhazikika kwa mabatire ochokera ku silicon kudzera mu nano-size, carbon coating, pore formation ndi ukadaulo wina.
Zipangizo za kaboni zili ndi mphamvu yoyendetsa bwino, mtengo wotsika, komanso magwero ambiri. Zitha kusintha mphamvu yoyendetsa ndi kukhazikika pamwamba pa zinthu zopangidwa ndi silicon. Zimagwiritsidwa ntchito makamaka ngati zowonjezera zowongolera magwiridwe antchito a ma electrode opanda mphamvu ochokera ku silicon. Zipangizo za silicon-carbon ndiye njira yayikulu yopangira ma electrode opanda mphamvu ochokera ku silicon. Kuphimba kwa kaboni kumatha kusintha kukhazikika pamwamba pa zinthu zopangidwa ndi silicon, koma kuthekera kwake kuletsa kukulira kwa kuchuluka kwa silicon ndi kwachisawawa ndipo sikungathe kuthetsa vuto la kukulira kwa kuchuluka kwa silicon. Chifukwa chake, kuti zinthu zopangidwa ndi silicon ziwongolere kukhazikika, nyumba zokhala ndi mapokoso ziyenera kupangidwa. Kupera mpira ndi njira yopangidwa ndi mafakitale yokonzekera zinthu zopangidwa ndi nanomaterials. Zowonjezera zosiyanasiyana kapena zigawo zazinthu zitha kuwonjezeredwa ku slurry yomwe imapezeka popera mpira malinga ndi zofunikira pakupanga kwa zinthu zopangidwa ndi composite. Slurry imafalikira mofanana kudzera mu slurry zosiyanasiyana ndikuumitsidwa ndi spray. Panthawi youma nthawi yomweyo, tinthu tating'onoting'ono ndi zigawo zina mu slurry zimapanga mawonekedwe a pokoso. Pepalali limagwiritsa ntchito ukadaulo wa mafakitale komanso wosamalira chilengedwe wopera mpira ndi spray drying kuti likonzekere zinthu zopangidwa ndi silicon zokhala ndi mapokoso.
Kugwira ntchito kwa zinthu zopangidwa ndi silicon kungathenso kukonzedwa mwa kuwongolera mawonekedwe ndi mawonekedwe a kugawa kwa zinthu zopangidwa ndi silicon nanomaterials. Pakadali pano, zinthu zopangidwa ndi silicon zokhala ndi mawonekedwe osiyanasiyana ndi mawonekedwe ogawa zakonzedwa, monga silicon nanorods, porous graphite embedded nanosilicon, nanosilicon yogawidwa mu carbon spheres, silicon/graphene array porous structures, ndi zina zotero. Pamlingo womwewo, poyerekeza ndi nanoparticles, nanosheets zimatha kuletsa bwino vuto lophwanyika lomwe limayambitsidwa ndi kukula kwa voliyumu, ndipo zinthuzo zimakhala ndi kuchuluka kwakukulu kwa compaction. Kusakhazikika kwa nanosheets kumathanso kupanga kapangidwe ka porous. Kuti mulowe nawo gulu la silicon negative electrode exchange. Perekani malo osungira kuti kuchuluka kwa zinthu zopangidwa ndi silicon kukulire. Kuyambitsa ma carbon nanotubes (CNTs) sikungongowonjezera kuyendetsa bwino kwa zinthuzo, komanso kumalimbikitsa mapangidwe a mapangidwe a porous a zinthuzo chifukwa cha mawonekedwe ake amtundu umodzi. Palibe malipoti okhudza nyumba za porous zopangidwa ndi silicon nanosheets ndi CNTs. Pepalali likugwiritsa ntchito njira zogayira mipira, kugayira ndi kufalitsa, kuumitsa kwa spray, kupopera kaboni ndi njira zophikira calcium, ndikuyambitsa zolimbikitsira zokhala ndi mapokoso mu njira yokonzekera kuti akonze zinthu zopanga ma electrode opanda ma pokoso okhala ndi silicon zomwe zimapangidwa ndi kudzipangira ma silicon nanosheets ndi ma CNT. Njira yokonzekerayi ndi yosavuta, yosamalira chilengedwe, ndipo palibe zinyalala kapena zotsalira za zinyalala zomwe zimapangidwa. Pali malipoti ambiri okhudza kuphimba kaboni kwa zinthu zopangidwa ndi silicon, koma pali zokambirana zochepa zakuya za momwe kuphimba kumakhudzira. Pepalali limagwiritsa ntchito phula ngati gwero la kaboni kuti lifufuze zotsatira za njira ziwiri zophimba kaboni, kuphimba gawo lamadzimadzi ndi kuphimba gawo lolimba, pa zotsatira zophimba ndi momwe zinthu zopangidwa ndi silicon zimagwirira ntchito.
Kuyesera 1
1.1 Kukonzekera zinthu
Kukonzekera zinthu zopangidwa ndi silicon-carbon composite kumaphatikizapo magawo asanu: kupukuta mpira, kupukuta ndi kufalitsa, kuumitsa kwa spray, kuphimba kaboni ndi carbonization. Choyamba, yesani 500 g ya ufa woyamba wa silicon (wapakhomo, 99.99% kuyera), onjezerani 2000 g ya isopropanol, ndikuchita kupukuta mpira wonyowa pa liwiro la kupukuta mpira la 2000 r/min kwa maola 24 kuti mupeze slurry ya silicon ya nano-scale. Slurry ya silicon yomwe yapezeka imasamutsidwira ku thanki yosinthira kufalikira, ndipo zinthuzo zimawonjezedwa malinga ndi kuchuluka kwa silicon: graphite (yopangidwa ku Shanghai, kalasi ya batri): ma nanotubes a carbon (opangidwa ku Tianjin, kalasi ya batri): polyvinyl pyrrolidone (yopangidwa ku Tianjin, kalasi yowunikira) = 40:60:1.5:2. Isopropanol imagwiritsidwa ntchito kusintha zomwe zili zolimba, ndipo zomwe zili zolimba zimapangidwa kuti zikhale 15%. Kupera ndi kufalitsa kumachitika pa liwiro la kufalikira la 3500 r/min kwa maola 4. Gulu lina la slurry popanda kuwonjezera CNTs limayerekezeredwa, ndipo zipangizo zina ndizofanana. Slurry yomwe yapezeka imasamutsidwira ku thanki yodyetsera yopopera, ndipo kupopera kumachitidwa mumlengalenga wotetezedwa ndi nayitrogeni, ndipo kutentha kwa kulowa ndi kutuluka kumakhala 180 ndi 90 °C, motsatana. Kenako mitundu iwiri ya carbon coating inayerekezeredwa, solid phase coating ndi liquid phase coating. Njira yopopera yolimba ndi iyi: ufa wopopera umasakanizidwa ndi 20% asphalt powder (yopangidwa ku Korea, D50 ndi 5 μm), yosakanizidwa mu makina osakanizira kwa mphindi 10, ndipo liwiro losakaniza ndi 2000 r/min kuti mupeze ufa wopopera kale. Njira yopopera yamadzi ndi iyi: ufa wopopera umawonjezeredwa ku xylene solution (yopangidwa ku Tianjin, analytical grade) yokhala ndi 20% asphalt yosungunuka mu ufa pamlingo wolimba wa 55%, ndipo vacuum imasunthidwa mofanana. Kuphika mu uvuni wa vacuum pa 85℃ kwa maola 4, kuyika mu makina osakanizira kuti musakanize, liwiro losakaniza ndi 2000 r/min, ndipo nthawi yosakaniza ndi mphindi 10 kuti mupeze ufa wothira kale. Pomaliza, ufa wothira kale unayikidwa mu uvuni wozungulira pansi pa mpweya wa nayitrogeni pa kutentha kwa 5°C/min. Choyamba unasungidwa kutentha kosasintha kwa 550°C kwa maola awiri, kenako unapitirira kutentha mpaka 800°C ndikusungidwa kutentha kosasintha kwa maola awiri, kenako unaziziritsidwa mwachilengedwe mpaka pansi pa 100°C ndikutulutsidwa kuti mupeze zinthu zopangidwa ndi silicon-carbon composite.
1.2 Njira zofotokozera makhalidwe
Kugawa kwa tinthu tating'onoting'ono kwa zinthuzo kunafufuzidwa pogwiritsa ntchito chida choyesera kukula kwa tinthu tating'onoting'ono (Mastersizer 2000 version, yopangidwa ku UK). Ufa womwe unapezedwa mu gawo lililonse unayesedwa pofufuza maikulosikopu ya electron (Regulus8220, yopangidwa ku Japan) kuti awone mawonekedwe ndi kukula kwa ufawo. Kapangidwe ka gawo la zinthuzo kanafufuzidwa pogwiritsa ntchito X-ray powder diffraction analyzer (D8 ADVANCE, yopangidwa ku Germany), ndipo kapangidwe ka zinthuzo kanafufuzidwa pogwiritsa ntchito energy spectrum analyzer. Zinthu zomwe zinapezedwa za silicon-carbon composite zinagwiritsidwa ntchito kupanga batani la theka la selo la chitsanzo cha CR2032, ndipo chiŵerengero cha kulemera kwa silicon-carbon: SP: CNT: CMC: SBR chinali 92:2:2:1.5:2.5. Electrode yotsutsana ndi pepala lachitsulo la lithiamu, electrolyte ndi electrolyte yogulitsa (chitsanzo 1901, chopangidwa ku Korea), diaphragm ya Celgard 2320 imagwiritsidwa ntchito, mphamvu yamagetsi ndi mphamvu yotulutsa ndi 0.005-1.5 V, mphamvu ndi mphamvu yotulutsa ndi 0.1 C (1C = 1A), ndipo mphamvu yochotsera ndi 0.05 C.
Pofuna kufufuza bwino momwe zinthu zopangidwa ndi silicon-carbon composite zimagwirira ntchito, batire yaying'ono yofewa yopangidwa ndi laminated 408595 inapangidwira. Electrode yabwino imagwiritsa ntchito NCM811 (yopangidwa ku Hunan, batire ya grade), ndipo graphite ya electrode yoipa imaphatikizidwa ndi 8% ya silicon-carbon. Fomula ya electrode yabwino ndi 96% NCM811, 1.2% polyvinylidene fluoride (PVDF), 2% conductive agent SP, 0.8% CNT, ndipo NMP imagwiritsidwa ntchito ngati dispersant; fomula ya electrode yoipa ndi 96% ya composite negative electrode material, 1.3% CMC, 1.5% SBR 1.2% CNT, ndipo madzi amagwiritsidwa ntchito ngati dispersant. Pambuyo posakaniza, kuphimba, kupukuta, kudula, lamination, kulumikiza ma tabo, kulongedza, kuphika, jakisoni wamadzimadzi, kugawa ndi mphamvu, mabatire a 408595 a laminated soft pack okhala ndi mphamvu ya 3 Ah adakonzedwa. Kugwira ntchito kwa 0.2C, 0.5C, 1C, 2C ndi 3C komanso kugwira ntchito kwa cycle ya 0.5C charge ndi 1C discharge zinayesedwa. Mphamvu ya charge ndi discharge inali 2.8-4.2 V, constant current ndi constant voltage charge, ndipo cut-off current inali 0.5C.
2 Zotsatira ndi Kukambirana
Ufa woyamba wa silicon unawonedwa pogwiritsa ntchito scanning electron microscopy (SEM). Ufa wa silicon unali wosakhazikika bwino ndi kukula kwa tinthu tosakwana 2μm, monga momwe zasonyezedwera pa Chithunzi 1(a). Pambuyo pogaya mpira, kukula kwa ufa wa silicon kunachepetsedwa kwambiri kufika pa 100 nm [Chithunzi 1(b)]. Kuyesa kwa kukula kwa tinthu kunawonetsa kuti D50 ya ufa wa silicon pambuyo pogaya mpira inali 110 nm ndipo D90 inali 175 nm. Kufufuza mosamala mawonekedwe a ufa wa silicon pambuyo pogaya mpira kukuwonetsa kapangidwe kosweka (mapangidwe a kapangidwe kosweka adzatsimikiziridwanso kuchokera ku SEM yodutsa pambuyo pake). Chifukwa chake, deta ya D90 yomwe idapezeka kuchokera ku mayeso a kukula kwa tinthu iyenera kukhala kutalika kwa nanosheet. Kuphatikiza ndi zotsatira za SEM, zitha kuweruzidwa kuti kukula kwa nanosheet yomwe yapezeka ndi yocheperako kuposa mtengo wofunikira wa 150 nm wa kusweka kwa ufa wa silicon panthawi yoyatsira ndi kutulutsa mu gawo limodzi. Kupangidwa kwa mawonekedwe osweka kumachitika makamaka chifukwa cha mphamvu zosiyanasiyana zolekanitsa za mapulaneti a kristalo a silicon yonyezimira, yomwe pakati pake mapulaneti a silicon {111} ali ndi mphamvu zochepa zolekanitsa kuposa mapulaneti a kristalo {100} ndi {110}. Chifukwa chake, mapulaneti a kristalo awa amachepetsedwa mosavuta ndi kugaya mpira, ndipo pamapeto pake amapanga kapangidwe kosweka. Kapangidwe kosweka kamakhala kothandiza kuti mapangidwe osasunthika asonkhanitsidwe, kumasunga malo oti silicon ikule, ndikuwonjezera kukhazikika kwa zinthuzo.
Dothi lokhala ndi nano-silicon, CNT ndi graphite linapopedwa, ndipo ufawo usanapopedwe ndi SEM unayesedwa ndi SEM. Zotsatira zake zikuwonetsedwa mu Chithunzi 2. Graphite matrix yomwe yawonjezeredwa musanapopedwe ndi kapangidwe ka flake kamene kali ndi kukula kwa 5 mpaka 20 μm [Chithunzi 2(a)]. Kuyesa kwa kukula kwa tinthu tating'onoting'ono kwa graphite kukuwonetsa kuti D50 ndi 15μm. Ufa womwe umapezeka mutapopedwa uli ndi mawonekedwe ozungulira [Chithunzi 2(b)], ndipo zitha kuwoneka kuti graphite yaphimbidwa ndi wosanjikiza wokutira mutapopedwa. D50 ya ufa mutapopedwa ndi 26.2 μm. Makhalidwe a tinthu tachiwiri adawonedwa ndi SEM, kuwonetsa mawonekedwe a kapangidwe kotayirira kamene kamasonkhanitsidwa ndi zinthu zina [Chithunzi 2(c)]. Kapangidwe ka matope kamapangidwa ndi ma nanosheet a silicon ndi ma CNT olumikizana [Chithunzi 2(d)], ndipo malo enieni a mayeso (BET) ndi okwera kufika 53.3 m2/g. Chifukwa chake, pambuyo popopera, ma silicon nanosheets ndi ma CNT amadzisonkhanitsa okha kuti apange kapangidwe kokhala ndi mabowo.
Gawo lokhala ndi mapovu linakonzedwa ndi utoto wa kaboni wamadzimadzi, ndipo pambuyo powonjezera utoto wa kaboni woyambirira ndi kaboni, SEM idawonedwa. Zotsatira zake zikuwonetsedwa mu Chithunzi 3. Pambuyo popaka utoto wa kaboni, pamwamba pa tinthu tachiwiri timakhala tosalala, ndi utoto wowonekera bwino, ndipo utotowo umatha, monga momwe zasonyezedwera mu Zithunzi 3(a) ndi (b). Pambuyo popaka utoto, utoto wozungulira pamwamba umasunga mawonekedwe abwino a utoto [Chithunzi 3(c)]. Kuphatikiza apo, chithunzi cha SEM chodutsa mbali imodzi chikuwonetsa tinthu tating'onoting'ono tokhala ngati mizere [Chithunzi 3(d)], zomwe zimagwirizana ndi mawonekedwe a nanosheets, zomwe zimatsimikiziranso kupangidwa kwa ma nanosheets a silicon pambuyo pogaya mpira. Kuphatikiza apo, Chithunzi 3(d) chikuwonetsa kuti pali zodzaza pakati pa ma nanosheets ena. Izi makamaka chifukwa cha kugwiritsa ntchito njira yopaka utoto wamadzimadzi. Yankho la asphalt lidzalowa m'zinthuzo, kotero kuti pamwamba pa ma nanosheets amkati a silicon amapeza utoto woteteza utoto wa kaboni. Chifukwa chake, pogwiritsa ntchito utoto wamadzimadzi, kuwonjezera pa kupeza utoto wachiwiri wa tinthu tating'onoting'ono, utoto wa kaboni kawiri wa utoto woyamba ungapezenso. Ufa wopangidwa ndi kaboni unayesedwa ndi BET, ndipo zotsatira za mayeso zinali 22.3 m2/g.
Ufa wopangidwa ndi kaboni unayesedwa kusanthula mphamvu ya spectrum (EDS), ndipo zotsatira zake zikuwonetsedwa mu Chithunzi 4(a). Pakati pa micron ndi gawo la C, lofanana ndi graphite matrix, ndipo chophimba chakunja chili ndi silicon ndi oxygen. Kuti apitirize kufufuza kapangidwe ka silicon, mayeso a X-ray diffraction (XRD) adachitika, ndipo zotsatira zake zikuwonetsedwa mu Chithunzi 4(b). Zipangizozo zimapangidwa makamaka ndi graphite ndi silicon ya kristalo imodzi, yopanda mawonekedwe omveka bwino a silicon oxide, zomwe zikusonyeza kuti gawo la oxygen la mayeso a energy spectrum limachokera makamaka ku okosijeni wachilengedwe pamwamba pa silicon. Zipangizo zophatikizika za silicon-carbon zalembedwa ngati S1.
Zinthu zopangidwa ndi silicon-carbon S1 zokonzedwa zinayesedwa kupanga theka la selo ndi mayeso otulutsa mphamvu. Mzere woyamba wotulutsa mphamvu ukuwonetsedwa mu Chithunzi 5. Mphamvu yeniyeni yosinthika ndi 1000.8 mAh/g, ndipo mphamvu yoyamba yogwira ntchito ndi 93.9%, zomwe ndi zapamwamba kuposa mphamvu yoyamba ya zinthu zambiri zopangidwa ndi silicon popanda pre-lithiation yomwe yanenedwa m'mabuku. Mphamvu yoyamba ikuwonetsa kuti zinthu zopangidwa ndi silicon-carbon zomwe zakonzedwa zili ndi kukhazikika kwakukulu. Pofuna kutsimikizira zotsatira za kapangidwe ka ma porous, conductive network ndi carbon coating pa kukhazikika kwa zinthu za silicon-carbon, mitundu iwiri ya zinthu zopangidwa ndi silicon-carbon zinakonzedwa popanda kuwonjezera CNT komanso popanda carbon coating yoyamba.
Kapangidwe ka ufa wopangidwa ndi kaboni wa zinthu zopangidwa ndi silicon-carbon popanda kuwonjezera CNT kakuwonetsedwa mu Chithunzi 6. Pambuyo pa kuphimba ndi kuyika kaboni pa gawo lamadzimadzi, wosanjikiza wokutira ukhoza kuwoneka bwino pamwamba pa tinthu tachiwiri mu Chithunzi 6(a). SEM yopingasa ya zinthu zopangidwa ndi kaboni ikuwonetsedwa mu Chithunzi 6(b). Kuyika kwa ma nanosheets a silicon kuli ndi mawonekedwe obowola, ndipo mayeso a BET ndi 16.6 m2/g. Komabe, poyerekeza ndi nkhani ya CNT [monga momwe zasonyezedwera mu Chithunzi 3(d), mayeso a BET a ufa wake wopangidwa ndi kaboni ndi 22.3 m2/g], kuchuluka kwa nano-silicon stacking mkati ndi kwakukulu, zomwe zikusonyeza kuti kuwonjezera kwa CNT kungathandize kupanga kapangidwe ka ma porous. Kuphatikiza apo, zinthuzo zilibe netiweki yoyendetsera ma conductive atatu yopangidwa ndi CNT. Zinthu zopangidwa ndi silicon-carbon zimalembedwa ngati S2.
Makhalidwe a kapangidwe ka zinthu zopangidwa ndi silicon-carbon zomwe zimapangidwa ndi solid-phase carbon coating akuwonetsedwa mu Chithunzi 7. Pambuyo pa carbonization, pali wosanjikiza woonekera bwino pamwamba, monga momwe zasonyezedwera mu Chithunzi 7(a). Chithunzi 7(b) chikuwonetsa kuti pali tinthu tating'onoting'ono tomwe timaoneka ngati mizere m'gawo lopingasa, zomwe zikugwirizana ndi mawonekedwe a nanosheets. Kusonkhanitsa kwa nanosheets kumapanga kapangidwe ka matope. Palibe chodzaza chowonekera pamwamba pa nanosheets zamkati, zomwe zikusonyeza kuti solid-phase carbon coating imangopanga wosanjikiza wa carbon coating wokhala ndi kapangidwe ka matope, ndipo palibe wosanjikiza wamkati wa silicon nanosheets. Zinthu zopangidwa ndi silicon-carbon izi zalembedwa ngati S3.
Mayeso a batani la theka la selo ndi kuyeretsa adachitika pa S2 ndi S3. Mphamvu yeniyeni ndi mphamvu yoyamba ya S2 inali 1120.2 mAh/g ndi 84.8%, motsatana, ndipo mphamvu yeniyeni ndi mphamvu yoyamba ya S3 inali 882.5 mAh/g ndi 82.9%, motsatana. Mphamvu yeniyeni ndi mphamvu yoyamba ya chitsanzo cha S3 chokhala ndi gawo lolimba ndizo zinali zochepa kwambiri, zomwe zikusonyeza kuti kaboni yokha ndi yophimba kapangidwe ka maporous, ndipo kaboni yophimba ya ma nanosheet amkati a silicon sinachitike, zomwe sizikanatha kupereka mphamvu yonse ya zinthu zopangidwa ndi silicon ndipo sizikanatha kuteteza pamwamba pa zinthu zopangidwa ndi silicon. Mphamvu yoyamba ya chitsanzo cha S2 popanda CNT inalinso yotsika kuposa ya zinthu zopangidwa ndi silicon-carbon zomwe zili ndi CNT, zomwe zikusonyeza kuti pamaziko a wosanjikiza wabwino wophimba, netiweki yoyendetsa ndi kapangidwe kapamwamba ka maporous zimathandiza kuti mphamvu ya mphamvu ndi kutulutsa mphamvu kwa zinthu zopangidwa ndi silicon-carbon ziwonjezeke.
Zipangizo za S1 silicon-carbon zinagwiritsidwa ntchito kupanga batire yaying'ono yofewa kuti ione momwe liwiro limagwirira ntchito komanso momwe limagwirira ntchito. Mzere wa liwiro la kutulutsa ukuwonetsedwa pa Chithunzi 8(a). Mphamvu zotulutsira za 0.2C, 0.5C, 1C, 2C ndi 3C ndi 2.970, 2.999, 2.920, 2.176 ndi 1.021 Ah, motsatana. Mphamvu zotulutsira za 1C ndi zapamwamba kwambiri mpaka 98.3%, koma mphamvu zotulutsira za 2C zimatsika kufika pa 73.3%, ndipo mphamvu zotulutsira za 3C zimatsika kwambiri kufika pa 34.4%. Kuti mulowe nawo gulu la kusinthana kwa ma electrode opanda silicon, chonde onjezani WeChat: shimobang. Ponena za kuchuluka kwa kutchaja, mphamvu zotulutsira za 0.2C, 0.5C, 1C, 2C ndi 3C ndi 3.186, 3.182, 3.081, 2.686 ndi 2.289 Ah, motsatana. Chiwongola dzanja cha 1C ndi 96.7%, ndipo chiwongola dzanja cha 2C chikufikirabe 84.3%. Komabe, poona momwe chongola dzanja chimakhalira mu Chithunzi 8(b), nsanja yochapira ya 2C ndi yayikulu kwambiri kuposa nsanja yochapira ya 1C, ndipo mphamvu yake yochapira yamagetsi yosasintha imakhala yambiri (55%), zomwe zikusonyeza kuti polarization ya batri yochapiranso ya 2C ndi yayikulu kale. Zipangizo za silicon-carbon zili ndi mphamvu yabwino yochapira ndi kutulutsa mphamvu pa 1C, koma mawonekedwe a zinthuzo ayenera kukonzedwanso kuti zigwire ntchito bwino kwambiri. Monga momwe zasonyezedwera mu Chithunzi 9, pambuyo pa ma cycle 450, chiwongola dzanja chosungira mphamvu ndi 78%, kusonyeza kuti chiwongola dzanja chikugwira ntchito bwino.
Mkhalidwe wa pamwamba pa electrode isanayambe komanso itatha kuzungulira unafufuzidwa ndi SEM, ndipo zotsatira zake zawonetsedwa mu Chithunzi 10. Isanafike kuzungulira, pamwamba pa zinthu za graphite ndi silicon-carbon zimakhala zomveka bwino [Chithunzi 10(a)]; pambuyo pa kuzungulira, wosanjikiza wokutira umapangidwa bwino pamwamba [Chithunzi 10(b)], womwe ndi filimu yokhuthala ya SEI. Kuuma kwa filimu ya SEI Kugwiritsa ntchito lithiamu yogwira ntchito ndikokwera, komwe sikuthandiza kuti kuzungulira kuyende bwino. Chifukwa chake, kulimbikitsa kupangidwa kwa filimu yosalala ya SEI (monga kapangidwe ka filimu yopangira ya SEI, kuwonjezera zowonjezera zoyenera za electrolyte, ndi zina zotero) kungathandize kuti kuzungulira kuyende bwino. Kuwona kwa SEM kwa tinthu ta silicon-carbon pambuyo pa kuzungulira [Chithunzi 10(c)] kukuwonetsa kuti tinthu ta silicon tomwe timakhala ngati mzere tayamba kukhala tolimba ndipo kapangidwe kake kamakhala ndi mapokoso kachotsedwa kwenikweni. Izi makamaka chifukwa cha kukula kosalekeza kwa voliyumu ndi kupindika kwa zinthu za silicon-carbon panthawi ya kuzungulira. Chifukwa chake, kapangidwe ka mapokoso kayenera kuwonjezeredwa kuti kapereke malo okwanira osungira kuti kuchuluka kwa zinthu zopangidwa ndi silicon kukule.
3 Mapeto
Kutengera kukula kwa voliyumu, kusinthasintha kwa mpweya komanso kukhazikika kwa ma electrode opanda mphamvu ochokera ku silicon, pepalali limapanga kusintha kolunjika, kuyambira pakupanga mawonekedwe a ma silicon nanosheets, kapangidwe ka ma porous structure, kapangidwe ka ma conductive network ndi kuphimba kwathunthu kwa carbon kwa tinthu tating'onoting'ono ta secondary, kuti zinthu zonse za silicon-based negative electrode zikhale zokhazikika. Kusonkhanitsa ma silicon nanosheets kumatha kupanga kapangidwe ka porous. Kuyambitsa CNT kudzalimbikitsanso kupangidwa kwa kapangidwe ka porous. Zinthu za silicon-carbon composite zomwe zimapangidwa ndi madzi zimakhala ndi double carbon coating effect kuposa zomwe zimapangidwa ndi solid phase coating, ndipo zimawonetsa mphamvu yayikulu komanso magwiridwe antchito oyamba. Kuphatikiza apo, kugwira ntchito koyamba kwa zinthu za silicon-carbon composite zomwe zili ndi CNT ndikokwera kuposa komwe kulibe CNT, komwe kumachitika makamaka chifukwa cha kuchuluka kwa mphamvu ya kapangidwe ka porous yochepetsera kuchuluka kwa zinthu zochokera ku silicon. Kuyambitsa CNT kudzapanga netiweki yoyendetsera zinthu ya magawo atatu, kukonza kusinthasintha kwa zinthu zochokera ku silicon, ndikuwonetsa magwiridwe antchito abwino pa 1C; ndipo zinthuzo zikuwonetsa magwiridwe antchito abwino a cycle. Komabe, kapangidwe ka mapoko a zinthuzo kayenera kuwonjezeredwa kuti pakhale malo okwanira osungira kuti silicon ikule, ndikulimbikitsa kupangika kwa chitsulo chosalala.ndi filimu yokhuthala ya SEI kuti ipititse patsogolo magwiridwe antchito a zinthu zopangidwa ndi silicon-carbon.
Timaperekanso zinthu za graphite ndi silicon carbide zoyera kwambiri, zomwe zimagwiritsidwa ntchito kwambiri pokonza ma wafer monga oxidation, diffusion, ndi annealing.
Takulandirani makasitomala ochokera padziko lonse lapansi kuti adzatichezere kuti tikambirane zambiri!
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Nthawi yotumizira: Novembala-13-2024