Iibhetri zeLithium-ion ziphuhliswa ikakhulu kwicala lokuxinana kwamandla aphezulu. Kwiqondo lobushushu begumbi, i-silicon-based negative electrode materials alloy ne-lithium ukuvelisa i-lithium-rich product Li3.75Si isigaba, enomthamo othile ukuya kuthi ga kwi-3572 mAh/g, engaphezulu kakhulu kwethiyori ethile ye-graphite negative electrode 372 mAh/g. Nangona kunjalo, ngexesha lokutshaja ngokuphindaphindiweyo kunye nenkqubo yokukhupha izinto ze-silicon-based negative electrode, ukuguqulwa kwesigaba se-Si kunye ne-Li3.75Si kunokuvelisa ukwanda kwevolumu enkulu (malunga ne-300%), okuya kukhokelela kumgubo wesakhiwo sezinto ze-electrode kunye nokwakhiwa okuqhubekayo Ifilimu ye-SEI, kwaye ekugqibeleni ibangele ukuba amandla ehle ngokukhawuleza. Ishishini ikakhulu liphucula ukusebenza kwe-silicon-based negative electrode materials kunye nokuzinza kwe-silicon-based battery ngokusebenzisa i-nano-size, i-carbon coating, i-pore formation kunye nobunye ubuchwepheshe.
Izixhobo zekhabhoni zinokuqhuba kakuhle, ixabiso eliphantsi, kunye nemithombo ebanzi. Bangakwazi ukuphucula i-conductivity kunye nokuzinza kwendawo yezinto ezisekelwe kwi-silicon. Zisetyenziswa ngokukhethekileyo njengezongezo zokuphucula ukusebenza kwe-silicon-based negative electrode. Izinto ze-silicon-carbon zezona ziphambili zophuhliso lwe-silicon-based negative electrode. Ukugquma kwekhabhoni kunokuphucula ukuzinza komphezulu wezinto ezisekelwe kwi-silicon, kodwa ukukwazi ukuthintela ukwanda kwevolumu ye-silicon kuqhelekileyo kwaye akunakuyisombulula ingxaki yokwandiswa kwevolumu ye-silicon. Ngoko ke, ukwenzela ukuba kuphuculwe ukuzinza kwezinto ezisekelwe kwi-silicon, izakhiwo ze-porous kufuneka zakhiwe. Ukugaya ibhola yindlela yoshishino yokulungiselela ama-nanomaterials. Izongezo ezahlukeneyo okanye izinto eziphathekayo zingongezwa kwi-slurry efunyenwe ngokugaya ibhola ngokweemfuno zoyilo lwezinto ezidibeneyo. I-slurry isasazwe ngokulinganayo ngeendlela ezahlukeneyo ze-slurries kunye ne-spray-yomisiwe. Ngethuba lokumisa ngokukhawuleza, i-nanoparticles kunye nezinye izinto kwi-slurry ziya kwenza ngokuzenzekelayo iimpawu zesakhiwo se-porous. Eli phepha lisebenzisa ushishino kunye nokusingqongileyo ibhola lokusila kunye neteknoloji yokutshiza yokutshiza ukulungisa izinto ezisekelwe kwi-silicon.
Ukusebenza kwezinto ezisekelwe kwi-silicon nazo zingaphuculwa ngokulawula i-morphology kunye neempawu zokusabalalisa i-silicon nanomaterials. Okwangoku, izinto ezisekelwe kwi-silicon ezine-morphologies ezahlukahlukeneyo kunye neempawu zokusabalalisa zilungiselelwe, ezifana ne-silicon nanorods, i-graphite edibeneyo efakwe kwi-nanosilicon, i-nanosilicon isasazwe kwi-carbon spheres, i-silicon / i-graphene array array porous structures, njl. Kwinqanaba elifanayo, xa kuthelekiswa ne-nanoparticles , i-nanosheets inokuthi icinezele ngakumbi ingxaki yokutyumza okubangelwa ukwanda komthamo, kwaye izinto eziphathekayo zinezinga eliphezulu lokuxinana. Ukupakishwa okungacwangciswanga kwee-nanosheets kunokwenza ubume be-porous. Ukujoyina iqela le-silicon negative electrode exchange. Nikezela ngesithuba sesithinteli sokwandisa umthamo wezinto zesilicon. Ukuqaliswa kwe-carbon nanotubes (i-CNTs) ayikwazi nje ukuphucula ukuqhutyelwa kwezinto eziphathekayo, kodwa nokukhuthaza ukubunjwa kwezakhiwo ze-porous eziphathekayo ngenxa yeempawu ze-morphological one-dimensional. Akukho ngxelo malunga nezakhiwo ze-porous ezakhiwe nge-silicon nanosheets kunye ne-CNTs. Eli phepha lamkela ukugaya ibhola, ukugawula kunye nokusasazwa, ukutshiza, ukutshiza, ukuthambisa i-carbon pre-coating kunye neendlela zokubala, kwaye lazisa abakhuthazi be-porous kwinkqubo yokulungiselela ukulungiselela izixhobo ze-electrode ezimbi ezisekelwe kwi-silicon ezenziwe ngokuzidibanisa kwe-silicon nanosheets kunye CNTs. Inkqubo yokulungiselela ilula, ihambelana nokusingqongileyo, kwaye akukho nkunkuma yolwelo okanye inkunkuma eyenziwayo. Kukho iingxelo ezininzi zoncwadi malunga nokufakwa kwekhabhoni yezinto ezisekelwe kwi-silicon, kodwa kukho iingxoxo ezimbalwa ezinzulu malunga nomphumo wokugquma. Eli phepha lisebenzisa i-asphalt njengomthombo wekhabhoni ukuphanda imiphumo yeendlela ezimbini zokugqoka i-carbon, i-liquid phase coating and solid phase coating, kwi-coating effect kunye nokusebenza kwe-silicon-based negative electrode materials.
1 Linge
1.1 Ukulungiswa kwezinto
Ukulungiswa kwezixhobo ezidibeneyo ze-silicon-carbon-carbon composite ikakhulu kubandakanya amanyathelo amahlanu: ukugaya ibhola, ukugaya kunye nokusabalalisa, ukutshiza ukutshiza, i-carbon pre-coating kunye ne-carbonization. Okokuqala, linganisa i-500 g ye-silicon powder yokuqala (yasekhaya, i-99.99% yococeko), yongeza i-2000 g ye-isopropanol, kwaye wenze i-milling yebhola emanzi kwi-speed yokugaya ibhola ye-2000 r / min kwi-24 h ukufumana i-nano-scale silicon slurry. I-silicon slurry efunyenweyo ikhutshelwa kwitanki yokudlulisa i-dispersion, kwaye izinto zongezwa ngokomlinganiselo we-silicon: igraphite (eveliswe eShanghai, ibakala lebhetri): i-carbon nanotubes (eveliswe eTianjin, ibakala lebhetri): i-polyvinyl pyrrolidone (eveliswayo eTianjin, ibakala lokuhlalutya) = 40:60:1.5:2. I-Isopropanol isetyenziselwa ukulungelelanisa umxholo oqinileyo, kwaye umxholo oqinileyo wenzelwe ukuba ube yi-15%. Ukugaya kunye nokusabalalisa kwenziwa kwisantya sokusasazeka kwe-3500 r / min kwi-4 h. Elinye iqela le-slurries ngaphandle kokongeza i-CNTs lithelekiswa, kwaye ezinye izinto ziyafana. Udaka olufunyenweyo olusasaziweyo luthi ke ludluliselwe kwitanki yokomisa isitshizi, kwaye ukomiswa ngesitshizi kwenziwa kwiatmosfera ekhuselwe yinitrogen, kunye namaqondo obushushu okungena nokuphuma abe yi-180 kunye ne-90 °C, ngokulandelelanayo. Emva koko kwathelekiswa iindidi ezimbini zokwaleka kwekhabhoni, ukwaleka kwesigaba esiqinileyo kunye nokwaleka kwesigaba solwelo. Indlela yokwaleka yesigaba esiqinileyo yile: i-spray-dried powder ixutywe kunye ne-20% ye-asphalt powder (eyenziwe eKorea, i-D50 yi-5 μm), ixutywe kumxube womatshini we-10 min, kunye nesantya sokuxuba i-2000 r / min ukufumana. umgubo oqatywe ngaphambili. Indlela yokwaleka yesigaba solwelo yile: umgubo otshisiweyo owomileyo wongezwa kwisisombululo sexylene (eyenziwe eTianjin, ibakala lohlalutyo) equlethe i-20% yeasphalt enyibilikiswe kumgubo kumxholo oqinileyo we-55%, kunye ne-vacuum evuselelwe ngokulinganayo. Bhaka kwi-oven vacuum kwi-85 ℃ ye-4h, ubeke kwi-mixer mechanical yokuxuba, isantya sokuxuba si-2000 r / min, kwaye ixesha lokuxuba liyi-10 min ukufumana ipowder efakwe ngaphambili. Ekugqibeleni, i-powder yangaphambili ifakwe i-calcined kwi-kiln ejikelezayo phantsi kwe-nitrogen emoyeni kwiqondo lokushisa kwe-5 ° C / min. Yayigcinwa kuqala kwiqondo lokushisa elingaguqukiyo le-550 ° C nge-2h, emva koko yaqhubeka ishushu ukuya kuma-800 ° C kwaye igcinwe kwiqondo lokushisa elingaguqukiyo i-2h, kwaye emva koko ipholile ngokwemvelo ukuya ngaphantsi kwe-100 ° C kwaye ikhutshwe ukuze ifumane i-silicon-carbon. imathiriyeli edibeneyo.
1.2 Iindlela zokulinganisa abalinganiswa
Ukusabalalisa ubungakanani bezinto eziphathekayo kuhlalutywe kusetyenziswa i-particle size tester (i-Mastersizer 2000 version, eyenziwe e-UK). Iipowders ezifunyenwe kwinqanaba ngalinye zavavanywa ngokuskena i-electron microscopy (i-Regulus8220, eyenziwe eJapan) ukuhlola i-morphology kunye nobukhulu bee powders. Isakhiwo sesigaba sezinto eziphathekayo sahlalutywa kusetyenziswa i-X-ray powder diffraction analyzer (i-D8 ADVANCE, eyenziwe eJamani), kwaye ukubunjwa kwezinto eziphathekayo kwahlalutywa kusetyenziswa i-analyzer ye-spectrum yamandla. Izinto ezifunyenweyo ze-silicon-carbon ezidibeneyo zisetyenziselwa ukwenza iqhosha le-half-cell yemodeli ye-CR2032, kunye nomlinganiselo wobunzima be-silicon-carbon: SP: CNT: CMC: SBR yi-92: 2: 2: 1.5: 2.5. I-electrode ye-counter yintsimbi ye-lithium sheet, i-electrolyte yi-electrolyte yorhwebo (imodeli ye-1901, eyenziwe eKorea), i-Celgard 2320 diaphragm isetyenzisiweyo, i-charge and discharge voltage range yi-0.005-1.5 V, intlawulo kunye nokukhutshwa ngoku yi-0.1 C. (1C = 1A), kunye nokukhutshwa okunqunyulwayo okwangoku ngu-0.05 C.
Ukuze uqhubele phambili ukuphanda ukusebenza kwe-silicon-carbon-composite materials, ibhetri encinci ye-soft-pack ye-408595 yenziwe. I-electrode efanelekileyo isebenzisa i-NCM811 (eyenziwe kwi-Hunan, ibakala lebhetri), kunye ne-graphite ye-electrode engafanelekanga i-doped kunye ne-8% yezinto ze-silicon-carbon. I-electrode positive slurry formula yi-96% NCM811, 1.2% polyvinylidene fluoride (PVDF), 2% i-agent conductive SP, 0.8% CNT, kunye ne-NMP isetyenziswa njenge-dispersant; i-electrode negative slurry formula yi-96% composite negative electrode material, 1.3% CMC, 1.5% SBR 1.2% CNT, kwaye amanzi asetyenziswa njenge dispersant. Emva kokuvuselela, ukugquma, ukuqengqeleka, ukusika, i-lamination, i-welding ye-tab, ukupakishwa, ukubhaka, inaliti yolwelo, ukubunjwa kunye nokwahlulahlula, i-408595 i-laminated encinci yeebhetri ezithambileyo ezinomthamo olinganisiweyo we-3 Ah zalungiswa. Ukusebenza kwezinga le-0.2C, 0.5C, 1C, 2C kunye ne-3C kunye nokusebenza komjikelo we-0.5C yokuhlawula kunye nokukhutshwa kwe-1C kwavavanywa. Uluhlu lwe-voltage ye-charge and discharge luyi-2.8-4.2 V, i-voltage eqhubekayo kunye ne-voltage eqhubekayo, kunye ne-cut-off current yi-0.5C.
2 Iziphumo kunye neNgxoxo
Ipowder yokuqala ye-silicon yabonwa ngokuskena i-electron microscopy (SEM). Ipowder ye-silicon yayingekho ngokungaqhelekanga i-granular kunye nesayizi ye-particle engaphantsi kwe-2μm, njengoko kuboniswe kuMfanekiso 1 (a). Emva kokugaya ibhola, ubukhulu be-silicon powder buncitshiswe kakhulu malunga ne-100 nm [Umfanekiso 1 (b)]. Uvavanyo lwesayizi ye-particle lubonise ukuba i-D50 ye-silicon powder emva kokugaya ibhola yayiyi-110 nm kwaye i-D90 yayiyi-175 nm. Uvavanyo olucokisekileyo lwe-morphology ye-silicon powder emva kokugaya ibhola kubonisa isakhiwo esiqhekezayo (ukubunjwa kwesakhiwo esiqhekezayo kuya kuqinisekiswa ngakumbi kwi-SEM ye-cross-sectional kamva). Ngoko ke, idatha ye-D90 efunyenwe kuvavanyo lwesayizi ye-particle kufuneka ibe ubude bobude be-nanosheet. Ukudibanisa neziphumo ze-SEM, kunokugwetywa ukuba ubungakanani be-nanosheet efunyenweyo buncinci kunexabiso elibalulekileyo le-150 nm yokuphulwa kwe-silicon powder ngexesha lokutshaja kunye nokukhupha ubuncinci kwi-dimension enye. Ukubunjwa kwe-flaky morphology kungenxa ye-dissociation yamandla ahlukeneyo e-crystal planes ye-crystalline silicon, phakathi kwayo i- {111} i-plane ye-silicon inamandla aphantsi okuqhawula kune- {100} kunye {110} ne-crystal planes. Ngoko ke, le planethi yekristale iyancipha ngokulula ngokugaya ibhola, kwaye ekugqibeleni yenza isakhiwo esinqabileyo. Ubume be-flaky buhambelana nokuqokelela kwezakhiwo ezikhululekile, zigcina indawo yokwandisa umthamo we-silicon, kunye nokuphucula ukuzinza kwezinto.
I-slurry equkethe i-nano-silicon, i-CNT kunye ne-graphite yafafazwa, kwaye i-powder ngaphambi nangemva kokutshiza ihlolwe yi-SEM. Iziphumo ziboniswe kuMzobo 2. I-matrix yegraphite eyongeziweyo ngaphambi kokutshiza isakhiwo se-flake esiqhelekileyo kunye nobukhulu be-5 ukuya kwi-20 μm [Umfanekiso 2 (a)]. Uvavanyo lokusabalalisa ubungakanani besuntswana legraphite lubonisa ukuba i-D50 yi-15μm. Umgubo ofunyenwe emva kokutshiza une-morphology ye-spherical [Figure 2 (b)], kwaye kunokubonwa ukuba igraphite igqunywe ngumaleko wokugquma emva kokutshiza. I-D50 yomgubo emva kokutshiza i-26.2 μm. Iimpawu ze-morphological ze-particle zesibini zabonwa yi-SEM, ebonisa iimpawu zesakhiwo se-porous esikhululekile esiqokelelwe ngama-nanomaterials [Umfanekiso 2 (c)]. Ulwakhiwo lwe-porous luqulunqwe nge-silicon nanosheets kunye ne-CNTs ezidityanisiweyo kunye [Umfanekiso 2 (d)], kunye nommandla othile wovavanyo (BET) uphezulu njenge-53.3 m2 / g. Ngoko ke, emva kokutshiza, i-silicon nanosheets kunye ne-CNTs i-self-assess ukuze yenze isakhiwo se-porous.
Umaleko we-porous waphathwa nge-carbon coating engamanzi, kwaye emva kokongeza i-carbon coating precursor pitch kunye ne-carbonization, ukuqwalaselwa kwe-SEM kwenziwa. Iziphumo ziboniswe kuMzobo 3. Emva kwe-carbon pre-coating, ubuso beengqungquthela zesibini buba bushelelezi, kunye nomgangatho ocacileyo wokugquma, kwaye ukugubungela kuphelile, njengoko kuboniswe kwiMifanekiso 3 (a) kunye (b). Emva kwe-carbonization, umaleko wokugquma komhlaba ugcina imo yokwambathisa elungileyo [Umfanekiso 3 (c)]. Ukongezelela, umfanekiso we-SEM we-cross-sectional ubonisa i-nanoparticles ene-striped-shaped nanoparticles [Umfanekiso 3 (d)], ohambelana neempawu ze-morphological ze-nanosheets, ngokuqhubekayo uqinisekisa ukubunjwa kwe-silicon nanosheets emva kokugaya ibhola. Ukongeza, uMzobo 3 (d) ubonisa ukuba kukho izihluzi phakathi kwezinye iinanosheets. Oku kungenxa yokusetyenziswa kwendlela yokwaleka kwesigaba solwelo. Isisombululo se-asphalt siya kungena kwizinto eziphathekayo, ukwenzela ukuba umphezulu we-silicon yangaphakathi nanosheets ufumane i-carbon coating layer protective. Ngoko ke, ngokusebenzisa i-liquid phase coating, ukongeza ekufumaneni isiphumo sesibini se-particle coating effect, i-double carbon coating effect ye-primary particle coating ingafumaneka. I-powder carbonized yavavanywa yi-BET, kwaye umphumo wokuvavanya wawuyi-22.3 m2 / g.
I-powder carbonized yayiphantsi kohlalutyo lwe-spectrum yamandla e-cross-sectional (EDS), kwaye iziphumo ziboniswe kuMzobo 4 (a). I-core ye-micron-size core yi-C component, ehambelana ne-graphite matrix, kwaye i-coating yangaphandle iqukethe i-silicon kunye ne-oxygen. Ukuqhubela phambili uphando ngesakhiwo se-silicon, uvavanyo lwe-X-ray diffraction (XRD) lwenziwa, kwaye iziphumo ziboniswe kuMzobo 4 (b). Izinto eziphathekayo ubukhulu becala zenziwe nge-graphite kunye ne-crystal-crystal silicon, ngaphandle kweempawu ezicacileyo ze-silicon oxide, ezibonisa ukuba inxalenye ye-oksijini yovavanyo lwe-spectrum yamandla ikakhulu ivela kwi-oxidation yendalo ye-silicon surface. Izinto ezihlanganisiweyo ze-silicon-carbon zirekhodwa njenge-S1.
I-silicon-carbon material elungiselelwe i-S1 yayiphantsi kweqhosha-uhlobo lwe-half-cell production kunye neemvavanyo zokukhutshwa kwentlawulo. I-curve yokuqala yokukhupha i-curve iboniswe kwi-Figure 5. Umthamo ochanekileyo oguqulwayo ngu-1000.8 mAh / g, kunye nokusebenza komjikelo wokuqala kuphezulu njenge-93.9%, ephezulu kunokusebenza kokuqala kwezinto ezininzi ezisekelwe kwi-silicon ngaphandle kwe-pre- lithiation ingxelo kuncwadi. Ukusebenza okuphezulu kokuqala kubonisa ukuba izinto ezilungiselelwe i-silicon-carbon composite inozinzo oluphezulu. Ukuze kuqinisekiswe imiphumo yesakhiwo se-porous, inethiwekhi ye-conductive kunye ne-carbon coating ekuzinzeni kwezinto ze-silicon-carbon, iintlobo ezimbini ze-silicon-carbon materials zalungiselelwa ngaphandle kokongeza i-CNT kwaye ngaphandle kwekhabhoni yokuqala.
I-morphology ye-carbonized powder ye-silicon-carbon composite material ngaphandle kokongeza i-CNT iboniswe kuMzobo 6. Emva kokugquma kwesigaba se-liquid kunye ne-carbonization, i-coating layer ingabonakala ngokucacileyo phezu kweengqungquthela zesibini kwi-Figure 6 (a). I-SEM ye-cross-sectional ye-carbonized material iboniswe kwi-Figure 6 (b). Ukupakishwa kwe-silicon nanosheets kuneempawu ze-porous, kwaye uvavanyo lwe-BET luyi-16.6 m2 / g. Nangona kunjalo, xa kuthelekiswa nemeko kunye ne-CNT [njengoko kuboniswe kwi-Figure 3 (d), uvavanyo lwe-BET lwepowder carbonized yi-22.3 m2 / g], ubuninzi be-nano-silicon stacking yangaphakathi buphezulu, ebonisa ukuba ukongezwa kwe-CNT kunokukhuthaza. ukubunjwa kwesakhiwo se-porous. Ukongezelela, izinto eziphathekayo azikho inethiwekhi ye-three-dimensional conductive eyakhiwe yi-CNT. Izinto ezihlanganisiweyo ze-silicon-carbon zirekhodwa njenge-S2.
Iimpawu ze-morphological ze-silicon-carbon composite material ezilungiselelwe yi-solid-phase carbon coating ziboniswa kuMzobo 7. Emva kwe-carbonization, kukho umgca ocacileyo wokugubungela phezu komhlaba, njengoko kuboniswe kuMfanekiso 7 (a). Umzobo 7 (b) ubonisa ukuba kukho i-nanoparticles ene-strip-shaped-shaped section in cross section, ehambelana neempawu ze-morphological ze-nanosheets. Ukuqokelela kwee-nanosheets kwenza isakhiwo se-porous. Akukho nto icacileyo yokuzalisa kumphezulu we-nanosheets yangaphakathi, ebonisa ukuba i-carbon-phase-coating eqinile yenza kuphela i-carbon coating layer ene-porous structure, kwaye akukho maleko yangaphakathi yokugquma kwii-silicon nanosheets. Le nto ye-silicon-carbon edibeneyo ibhalwe njenge-S3.
Iqhosha le-half-cell charge kunye novavanyo lokukhutshwa lwenziwa kwi-S2 kunye ne-S3. Umthamo othile kunye nokusebenza kokuqala kwe-S2 kwakuyi-1120.2 mAh / g kunye ne-84.8%, ngokulandelanayo, kunye nomthamo othile kunye nokusebenza kakuhle kokuqala kwe-S3 yi-882.5 mAh / g kunye ne-82.9%, ngokulandelanayo. Umthamo othile kunye nokusebenza kakuhle kokuqala kwesampulu ye-S3 yesigaba esiqinileyo yayiyeyona iphantsi, ebonisa ukuba kuphela i-carbon coating yesakhiwo se-porous eyenziwa, kwaye i-carbon coating ye-silicon nanosheets yangaphakathi ayizange yenziwe, engakwazi ukunika umdlalo opheleleyo. kumthamo othile wezinto ezisekelwe kwi-silicon kwaye ayikwazanga ukukhusela umgangatho wezinto ezisekelwe kwi-silicon. Ukusebenza kokuqala kwesampulu ye-S2 ngaphandle kwe-CNT kwakungaphantsi kwe-silicon-carbon-composite material equkethe i-CNT, ebonisa ukuba ngesiseko somgangatho omhle wokugquma, inethiwekhi ye-conductive kunye neqondo eliphezulu lesakhiwo se-porous luncedo ekuphuculeni. yentlawulo kunye nokukhupha ukusebenza kakuhle kwezinto ze-silicon-carbon.
Isixhobo se-silicon-carbon ye-S1 sasetyenziselwa ukwenza ibhetri encinci ethambileyo egcweleyo ukujonga ukusebenza komyinge kunye nokusebenza komjikelo. Isantya sokukhutshwa kwesantya siboniswe kuMfanekiso 8 (a). Amandla okukhutshwa kwe-0.2C, 0.5C, 1C, 2C kunye ne-3C yi-2.970, 2.999, 2.920, 2.176 kunye ne-1.021 Ah, ngokulandelanayo. Izinga lokukhutshwa kwe-1C liphezulu njenge-98.3%, kodwa izinga lokukhutshwa kwe-2C liyehla ukuya kwi-73.3%, kwaye izinga lokukhutshwa kwe-3C liyancipha ngakumbi kwi-34.4%. Ukuzimanya ne-silicon negative electrode exchange group, nceda wongeze i-WeChat: shimobang. Ngokwezinga lokutshaja, i-0.2C, 0.5C, 1C, 2C kunye ne-3C amandla okutshaja yi-3.186, 3.182, 3.081, 2.686 kunye ne-2.289 Ah, ngokulandelanayo. Izinga lokuhlawula i-1C yi-96.7%, kwaye i-2C yokuhlawula intlawulo isafikelela kwi-84.3%. Nangona kunjalo, ukujonga ijika lokutshaja kwi-Figure 8 (b), iqonga lokutshaja le-2C likhulu kakhulu kuneqonga lokutshaja le-1C, kwaye amandla ayo okutshaja ombane rhoqo athatha uninzi (55%), ebonisa ukuba i-polarization ye-2C yebhetri etshajwayo. sele inkulu kakhulu. Izinto ze-silicon-carbon zinokutshaja kakuhle kunye nokukhupha ukusebenza kwi-1C, kodwa iimpawu zesakhiwo sezinto eziphathekayo kufuneka ziphuculwe ngakumbi ukufezekisa ukusebenza kwezinga eliphezulu. Njengoko kuboniswe kwi-Figure 9, emva kwemijikelezo ye-450, izinga lokugcinwa kwamandla yi-78%, ebonisa ukusebenza kakuhle komjikelo.
Ubume bomgangatho we-electrode ngaphambi nangemva kokuba umjikelezo uphandwe yi-SEM, kwaye iziphumo ziboniswa kuMzobo 10. Ngaphambi komjikelezo, ubuso be-graphite kunye ne-silicon-carbon-carbon materials icacile [Umfanekiso 10 (a)]; emva komjikelo, umaleko wokugquma ngokucacileyo uveliswa kumphezulu [Umfanekiso 10(b)], eyifilimu eshinyeneyo ye-SEI. Ubunzima befilimu ye-SEIUkusetyenziswa kwe-lithium esebenzayo kuphezulu, okungahambelani nokusebenza komjikelo. Ngoko ke, ukukhuthaza ukubunjwa kwefilimu ye-SEI egudileyo (njengokwakhiwa kwefilimu ye-SEI eyenziweyo, ukongeza izongezo ezifanelekileyo ze-electrolyte, njl.) kunokuphucula ukusebenza komjikelo. Ukuqwalaselwa kwe-SEM ye-cross-sectional ye-silicon-carbon particles emva komjikelezo [Umfanekiso we-10 (c)] ubonisa ukuba i-nanoparticles ye-silicon ye-strip yasekuqaleni ibe yinto eninzi kwaye i-porous structure iye yapheliswa ngokusisiseko. Oku kubangelwa ikakhulu ukwanda komthamo oqhubekayo kunye nokucuthwa kwezinto ze-silicon-carbon ngexesha lomjikelo. Ke ngoko, ubume beporous kufuneka buphuculwe ngakumbi ukuze kubonelelwe ngesithuba esaneleyo se-buffer sokwandiswa komthamo wezinto ezisekwe kwisilicon.
3 Isiphelo
Ngokusekwe kukwandiswa komthamo, ukungaqhubi kakuhle kunye nozinzo olulambathayo lonxibelelwano lwe-silicon-based negative electrode materials, eli phepha lenza uphuculo olujoliswe kuyo, ukusuka kwi-morphology shape ye-silicon nanosheets, ukwakhiwa kwesakhiwo se-porous, ukwakhiwa kwenethiwekhi eqhubayo kunye ne-carbon coating epheleleyo yazo zonke iincinci zesibini. , ukuphucula ukuzinza kwe-silicon-based negative electrode materials ngokubanzi. Ukuqokelelwa kwe-silicon nanosheets kunokwenza isakhiwo se-porous. Ukuqaliswa kwe-CNT kuya kukhuthaza ngakumbi ukubunjwa kwesakhiwo se-porous. Izinto ezihlanganisiweyo ze-silicon-carbon ezilungiselelwe ngokugquma kwesigaba solwelo zinefuthe eliphindwe kabini lekhabhoni yokwaleka kunelo lilungiswe ngumgangatho oqinileyo wokugquma, kwaye ubonisa amandla athile aphezulu kunye nokusebenza kakuhle kokuqala. Ukongeza, ukusebenza kakuhle kokuqala kwe-silicon-carbon-composite material equkethe i-CNT iphezulu kunaleyo ingenayo i-CNT, eyona nto ibangelwa yinqanaba eliphezulu le-porous structure ukukwazi ukunciphisa umthamo wokwandiswa kwezinto ezisekelwe kwi-silicon. Ukuqaliswa kwe-CNT kuya kwakha inethiwekhi ye-three-dimensional conductive, ukuphucula ukuqhutyelwa kwezinto ezisekelwe kwi-silicon, kunye nokubonisa ukusebenza kakuhle kwezinga kwi-1C; kunye nezinto ezibonakalayo zibonisa ukusebenza kakuhle komjikelo. Nangona kunjalo, ubume bezinto eziphathekayo kufuneka bomelezwe ngakumbi ukubonelela ngesithuba esaneleyo se-buffer yokwandisa umthamo we-silicon, kunye nokukhuthaza ukubunjwa kwe-silicone egudileyo.kunye nefilimu eshinyeneyo ye-SEI yokuphucula ngakumbi ukusebenza komjikelo wezinto ezihlanganisiweyo ze-silicon-carbon.
Sikwabonelela ngeemveliso zegraphite ezicoceke kakhulu kunye nesilicon carbide, ezisetyenziswa ngokubanzi ekusetyenzweni kwe-wafer njenge-oxidation, i-diffusion, kunye ne-annealing.
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Ixesha lokuposa: Nov-13-2024