Iibhetri zeLithium-ion ziphuhliswa ikakhulu kwicala loxinano lwamandla aphezulu. Kwiqondo lobushushu begumbi, izinto ze-electrode ezingasebenzi kakuhle ezisekelwe kwisilicon zixutywa ne-lithium ukuvelisa imveliso ye-lithium-rich Li3.75Si phase, enomthamo othile ofikelela kwi-3572 mAh/g, ongaphezulu kakhulu kunomthamo othile wethiyori we-graphite negative electrode 372 mAh/g. Nangona kunjalo, ngexesha lenkqubo yokutshaja nokukhupha izinto ze-electrode ezingasebenzi kakuhle ezisekelwe kwisilicon, utshintsho lwesigaba seSi kunye neLi3.75Si lunokuvelisa ukwanda okukhulu komthamo (malunga ne-300%), okuya kukhokelela ekufakweni komgubo wesakhiwo sezinto ze-electrode kunye nokwakheka okuqhubekayo kwefilimu ye-SEI, kwaye ekugqibeleni kubangele ukuba amandla ehle ngokukhawuleza. Eli shishini liphucula kakhulu ukusebenza kwezinto ze-electrode ezingasebenzi kakuhle ezisekelwe kwisilicon kunye nokuzinza kweebhetri ezisekelwe kwisilicon ngokusebenzisa ubungakanani be-nano, i-carbon coating, ukwakheka kwe-pore kunye nezinye iiteknoloji.
Izinto zekhabhoni zinomoya oqhuba kakuhle, zibiza kancinci, kwaye zibanzi. Zinokuphucula umbane kunye nokuzinza komphezulu wezinto ezisekwe kwi-silicon. Zisetyenziswa ngokukhethekileyo njengezongezo zokuphucula ukusebenza kwee-electrode ezingezizo ezisekwe kwi-silicon. Izinto ze-silicon-carbon ziyindlela ephambili yophuhliso lwee-electrode ezingezizo ezisekwe kwi-silicon. Ukwaleka kwekhabhoni kunokuphucula ukuzinza komphezulu wezinto ezisekwe kwi-silicon, kodwa amandla ayo okuthintela ukwanda komthamo we-silicon aqhelekile kwaye akanakuyisombulula ingxaki yokwanda komthamo we-silicon. Ke ngoko, ukuze kuphuculwe ukuzinza kwezixhobo ezisekwe kwi-silicon, kufuneka kwakhiwe izakhiwo ezineembobo. Ukusila ibhola yindlela yemizi-mveliso yokulungiselela izinto ezincinci. Izongezo ezahlukeneyo okanye izinto eziphathekayo zingongezwa kwi-slurry efunyenwe ngokusila ibhola ngokweemfuno zoyilo lwezinto ezidityanisiweyo. I-slurry isasazwa ngokulinganayo kwii-slurry ezahlukeneyo kwaye yomiswe nge-spray. Ngexesha lenkqubo yokomisa kwangoko, ii-nanoparticles kunye nezinye izinto ezikwi-slurry ziya kwenza iimpawu zesakhiwo ezineembobo ngokuzenzekelayo. Eli phepha lisebenzisa iteknoloji yokusila ibhola kunye nokomisa nge-spray esekwe kwimizi-mveliso kunye neyokusingqongileyo ukulungiselela izinto ezisekwe kwi-silicon ezineembobo.
Ukusebenza kwezinto ezisekwe kwisilicon kunokuphuculwa ngokulawula imo kunye neempawu zokusasazwa kwezinto ze-silicon nanomaterials. Okwangoku, izinto ezisekwe kwisilicon ezineemo ezahlukeneyo kunye neempawu zokusasazwa sele zilungisiwe, ezifana ne-silicon nanorods, i-porous graphite embedded nanosilicon, i-nanosilicon esasazwa kwi-carbon spheres, izakhiwo ze-silicon/graphene array porous, njl. Kwisikali esifanayo, xa kuthelekiswa ne-nanoparticles, ii-nanosheets zinokuyicinezela ngcono ingxaki yokutyumza ebangelwa kukwanda kwevolumu, kwaye izinto zinoxinano oluphezulu lokuxinana. Ukufakwa okungacwangciswanga kwee-nanosheets nako kunokwenza isakhiwo se-porous. Ukujoyina iqela le-silicon negative electrode exchange. Nika indawo ye-buffer yokwandiswa kwevolumu yezinto ze-silicon. Ukungeniswa kwee-carbon nanotubes (CNTs) akunakuphucula kuphela ukuhanjiswa kwezinto, kodwa kukwakhuthaza ukwakheka kwezakhiwo ze-porous zezinto ngenxa yeempawu zazo ze-modeological ezinemilinganiselo enye. Akukho ngxelo kwizakhiwo ze-porous ezakhiwe zii-silicon nanosheets kunye nee-CNTs. Eli phepha lisebenzisa indlela yokugaya ibhola esebenzayo kwimizi-mveliso, ukugaya kunye nokusasazwa, ukomisa nge-spray, iindlela zokufaka i-carbon pre-coating kunye ne-calcination, kwaye lazisa abakhuthazi abaneembobo kwinkqubo yokulungiselela ukulungiselela izixhobo ze-electrode ezineembobo ezisekelwe kwi-silicon ezenziwe ngokuzihlanganisa kwe-silicon nanosheets kunye ne-CNTs. Inkqubo yokulungiselela ilula, inobuhlobo nokusingqongileyo, kwaye akukho manzi okanye inkunkuma ephumayo. Kukho iingxelo ezininzi zoncwadi malunga nokufakwa kwe-carbon kwezinto ezisekelwe kwi-silicon, kodwa zimbalwa iingxoxo ezinzulu malunga nesiphumo sokufakwa kwe-coating. Eli phepha lisebenzisa i-asphalt njengomthombo we-carbon ukuphanda iziphumo zeendlela ezimbini zokufakwa kwe-carbon, ukufakwa kwe-liquid phase kunye nokufakwa kwe-solid phase, kwisiphumo sokufakwa kwe-coating kunye nokusebenza kwezixhobo ze-electrode ezineembobo ezisekelwe kwi-silicon.
1 Uvavanyo
1.1 Ukulungiswa kwezinto
Ukulungiswa kwezinto ezidityanisiweyo ze-silicon-carbon ezinemingxuma kubandakanya ikakhulu amanyathelo amahlanu: ukugaywa kwebhola, ukugaya nokusasazwa, ukomisa nge-spray, ukugquma ikhabhoni ngaphambi kokufaka i-carbon kunye ne-carbonization. Okokuqala, linganisa i-500 g yomgubo we-silicon wokuqala (wasekhaya, ubumsulwa obuyi-99.99%), yongeza i-2000 g ye-isopropanol, kwaye wenze ukugaywa kwebhola emanzi ngesantya sokugaywa kwebhola esiyi-2000 r/min iiyure ezingama-24 ukuze ufumane i-silicon slurry enama-nano-scale. I-silicon slurry efunyenweyo idluliselwa kwitanki yokudlulisa ukusasazeka, kwaye izixhobo zongezwa ngokomlinganiselo wobunzima be-silicon: i-graphite (eveliswe eShanghai, inqanaba lebhetri): ii-carbon nanotubes (eveliswe eTianjin, inqanaba lebhetri): i-polyvinyl pyrrolidone (eveliswe eTianjin, inqanaba lohlalutyo) = 40:60:1.5:2. I-Isopropanol isetyenziselwa ukulungisa umxholo oqinileyo, kwaye umxholo oqinileyo wenzelwe ukuba yi-15%. Ukusila nokusasazwa kwenziwa ngesantya sokusasazeka se-3500 r/min kangangeeyure ezi-4. Elinye iqela le-slurry ngaphandle kokongeza ii-CNTs liyathelekiswa, kwaye ezinye izinto ziyafana. I-slurry esasazekileyo efunyenweyo emva koko idluliselwa kwitanki yokomisa ngokufutha, kwaye ukomisa ngokufutha kwenziwa kwindawo ekhuselweyo yi-nitrogen, kunye namaqondo obushushu okungena kunye nokuphuma angama-180 kunye nama-90 °C, ngokulandelelana. Emva koko kwathelekiswa iintlobo ezimbini ze-carbon coating, i-solid phase coating kunye ne-liquid phase coating. Indlela ye-solid phase coating yile: i-spray-dryed powder ixutywe ne-20% asphalt powder (eyenziwe eKorea, i-D50 yi-5 μm), ixutywe kwi-mechanical mixer imizuzu eli-10, kwaye isantya sokuxuba yi-2000 r/min ukufumana i-pre-coated powder. Indlela ye-liquid phase coating yile: i-spray-dryed powder yongezwa kwisisombululo se-xylene (eyenziwe eTianjin, i-analytical grade) equlethe i-20% asphalt enyibilikiswe kwi-powder kumxholo oqinileyo we-55%, kwaye i-vacuum ivuselelwe ngokulinganayo. Bhaka kwi-oven ene-vacuum kwi-85℃ kangangeeyure ezi-4, ufake kwi-mixer yomatshini ukuze uxube, isantya sokuxuba yi-2000 r/min, kwaye ixesha lokuxuba yimizuzu eli-10 ukuze ufumane umgubo ogqunywe kwangaphambili. Ekugqibeleni, umgubo ogqunywe kwangaphambili wafakwa kwi-oven ejikelezayo phantsi kwe-nitrogen atmosphere ngesantya sokufudumala se-5°C/min. Waqala wagcinwa kubushushu obungaguqukiyo be-550°C kangangeeyure ezi-2, emva koko waqhubeka nokufudumala ukuya kuthi ga kwi-800°C waza wagcinwa kubushushu obungaguqukiyo kangangeeyure ezi-2, waza emva koko wapholiswa ngokwendalo ukuya kuthi ga kwi-100°C waza wakhutshwa ukuze kufunyanwe izinto ezidityanisiweyo ze-silicon-carbon.
1.2 Iindlela zokuchonga abalinganiswa
Ukusasazwa kobungakanani bezinto ezisetyenzisiweyo kuhlalutywe kusetyenziswa isixhobo sokuvavanya ubungakanani bezinto ezisetyenzisiweyo (iMastersizer 2000 version, eyenziwe e-UK). Iipowder ezifunyenweyo kwinqanaba ngalinye zivavanyiwe ngokuskena i-electron microscopy (Regulus8220, eyenziwe eJapan) ukuze kuhlolwe imo kunye nobukhulu beepowder. Ulwakhiwo lwesigaba sezinto ezisetyenzisiweyo luhlalutywe kusetyenziswa i-X-ray powder diffraction analyzer (D8 ADVANCE, eyenziwe eJamani), kwaye ukwakheka kwezinto ezisetyenzisiweyo kuhlalutywe kusetyenziswa i-energy spectrum analyzer. Izinto ezifunyenweyo ze-silicon-carbon composite zisetyenziselwe ukwenza iqhosha lesiqingatha seseli yemodeli ye-CR2032, kwaye umlinganiselo wobunzima be-silicon-carbon: SP: CNT: CMC: SBR yayingu-92:2:2:1.5:2.5. I-electrode yekhawuntara yiphepha le-lithium yesinyithi, i-electrolyte yi-electrolyte yorhwebo (imodeli ka-1901, eyenziwe eKorea), kusetyenziswa i-diaphragm yeCelgard 2320, uluhlu lwe-charge kunye ne-discharge voltage yi-0.005-1.5 V, i-charge kunye ne-discharge current yi-0.1 C (1C = 1A), kwaye i-discharge cut-off current yi-0.05 C.
Ukuze kuphandwe ngakumbi ukusebenza kwezinto ezidityanisiweyo ze-silicon-carbon, kwenziwe ibhetri encinci ethambileyo ene-laminated 408595. I-electrode elungileyo isebenzisa i-NCM811 (eyenziwe eHunan, inqanaba lebhetri), kwaye i-graphite ye-electrode engalunganga ifakwe i-8% ye-silicon-carbon material. Ifomula ye-electrode echanekileyo ye-slurry yi-96% NCM811, i-1.2% ye-polyvinylidene fluoride (PVDF), i-2% ye-conductive agent SP, i-0.8% CNT, kwaye i-NMP isetyenziswa njenge-dispersant; ifomula ye-slurry ye-electrode engalunganga yi-96% ye-composite negative electrode material, i-1.3% CMC, i-1.5% SBR 1.2% CNT, kwaye amanzi asetyenziswa njenge-dispersant. Emva kokuxubha, ukugquma, ukuqengqa, ukusika, i-lamination, ukuwelda kwethebhu, ukupakisha, ukubhaka, i-liquid injection, ukwakheka kunye nokwahlulahlula umthamo, kwalungiswa iibhetri ze-408595 ezincinci ze-laminated ezinomthamo olinganiselweyo we-3 Ah. Kuvavanywe ukusebenza kwezinga le-0.2C, 0.5C, 1C, 2C kunye ne-3C kunye nokusebenza komjikelo wetshaja ye-0.5C kunye ne-1C discharge. Uluhlu lwe-charge kunye ne-discharge voltage yayiyi-2.8-4.2 V, i-constant current kunye ne-constant voltage charging, kwaye i-cut-off current yayiyi-0.5C.
2 Iziphumo kunye nengxoxo
Umgubo wokuqala we-silicon wabonwa ngokuskena i-electron microscopy (SEM). Umgubo we-silicon wawune-granular engacwangciswanga enobukhulu be-particle obungaphantsi kwe-2μm, njengoko kubonisiwe kuMfanekiso 1(a). Emva kokusila ibhola, ubungakanani bomgubo we-silicon bancitshiswa kakhulu baba malunga ne-100 nm [Umfanekiso 1(b)]. Uvavanyo lobungakanani be-particle lubonise ukuba i-D50 yomgubo we-silicon emva kokusila ibhola yayiyi-110 nm kwaye i-D90 yayiyi-175 nm. Uvavanyo olucokisekileyo lwe-morphology yomgubo we-silicon emva kokusila ibhola lubonisa isakhiwo esiqhekekileyo (ukwakheka kwesakhiwo esiqhekekileyo kuya kuqinisekiswa ngakumbi kwi-SEM enqamlezileyo kamva). Ke ngoko, idatha ye-D90 efunyenwe kuvavanyo lobungakanani be-particle kufuneka ibe bubungakanani bobude be-nanosheet. Idityaniswe neziphumo ze-SEM, kunokugwetywa ukuba ubungakanani be-nanosheet efunyenweyo buncinci kunexabiso elibalulekileyo le-150 nm yokuqhekeka komgubo we-silicon ngexesha lokutshaja nokukhupha ubuncinane kumlinganiselo omnye. Ukwakheka kwemo ye-flaky morphology kubangelwa ngamandla ahlukeneyo okuhlukana kwe-crystal planes ye-crystalline silicon, apho i-plane ye-silicon {111} inamandla okuhlukana aphantsi kune-plane ye-crystal {100} kunye ne-110}. Ke ngoko, le plane ye-crystal incitshiswa lula ngokusila ibhola, kwaye ekugqibeleni yenza isakhiwo esiqhekekileyo. Isakhiwo esiqhekekileyo silungele ukuqokelelana kwezakhiwo ezikhululekileyo, sigcina indawo yokwandisa umthamo we-silicon, kwaye siphucula uzinzo lwezinto.
I-slurry equlethe i-nano-silicon, i-CNT kunye ne-graphite yatshizwa, kwaye umgubo ngaphambi nasemva kokutshizwa wahlolwa yi-SEM. Iziphumo ziboniswe kuMfanekiso 2. I-graphite matrix eyongeziweyo ngaphambi kokutshizwa sisakhiwo esiqhelekileyo se-flake esinobukhulu obuyi-5 ukuya kwi-20 μm [Umfanekiso 2(a)]. Uvavanyo lokusasazwa kobungakanani be-particle lwe-graphite lubonisa ukuba i-D50 yi-15μm. Umgubo ofunyenwe emva kokutshizwa une-spherical morphology [Umfanekiso 2(b)], kwaye kunokubonwa ukuba i-graphite igqunywe ngumaleko wokugquma emva kokutshizwa. I-D50 yomgubo emva kokutshizwa yi-26.2 μm. Iimpawu ze-morphological zee-secondary particles zabonwa yi-SEM, zibonisa iimpawu zesakhiwo esikhululekileyo esine-porous esiqokelelwe yi-nanomaterials [Umfanekiso 2(c)]. Isakhiwo esine-porous senziwe ngama-silicon nanosheets kunye ne-CNTs ezidityaniswe [Umfanekiso 2(d)], kwaye indawo ethile yovavanyo (BET) iphezulu njenge-53.3 m2/g. Ngoko ke, emva kokutshiza, ii-silicon nanosheets kunye nee-CNT ziyazihlanganisa ngokwazo ukuze zenze isakhiwo esineembobo.
Umaleko onemingxuma uphathwe nge-liquid carbon coating, kwaye emva kokongeza i-carbon coating precursor pitch kunye ne-carbonization, kwenziwa uqwalaselo lwe-SEM. Iziphumo ziboniswe kuMfanekiso 3. Emva kokufakwa kwe-carbon pre-coating, umphezulu wee-secondary particles uba mpuluswa, kunye nomaleko ocacileyo wokugquma, kwaye uqweqwe lugqityiwe, njengoko kubonisiwe kwiMifanekiso 3(a) kunye (b). Emva kokufakwa kwe-carbonization, umaleko wokugquma umphezulu ugcina imeko entle yokugquma [Umfanekiso 3(c)]. Ukongeza, umfanekiso we-SEM onqamlezileyo ubonisa ii-nanoparticles ezimile njenge-strip [Umfanekiso 3(d)], ezihambelana neempawu ze-morphological zee-nanosheets, eziqinisekisa ngakumbi ukwakheka kwee-silicon nanosheets emva kokusila ibhola. Ukongeza, uMfanekiso 3(d) ubonisa ukuba kukho izizalisi phakathi kwezinye ii-nanosheets. Oku kungenxa yokusetyenziswa kwendlela yokugquma yesigaba solwelo. Isisombululo se-asphalt siya kungena kwizinto, ukuze umphezulu wee-silicon nanosheets zangaphakathi ufumane umaleko okhuselayo wokugquma ikhabhoni. Ngoko ke, ngokusebenzisa i-liquid phase coating, ukongeza ekufumaneni i-secondary particle coating effect, i-double carbon coating effect ye-primary particle coating nayo ingafumaneka. I-carbonized powder ivavanywe yi-BET, kwaye iziphumo zovavanyo yayiyi-22.3 m2/g.
Umgubo wecarbonized uhlolwe nge-cross-sectional energy spectrum analysis (EDS), kwaye iziphumo ziboniswe kuMfanekiso 4(a). I-micron-size core yi-C component, ehambelana ne-graphite matrix, kwaye i-coating yangaphandle ine-silicon kunye ne-oxygen. Ukuze kuphandwe ngakumbi ngesakhiwo se-silicon, kwenziwe uvavanyo lwe-X-ray diffraction (XRD), kwaye iziphumo ziboniswe kuMfanekiso 4(b). Le nto yenziwe kakhulu yi-graphite kunye ne-single-crystal silicon, engenazo iimpawu ze-silicon oxide ezicacileyo, nto leyo ebonisa ukuba i-oxygen component yovavanyo lwe-energy spectrum ivela kakhulu kwi-oxidation yendalo yomphezulu we-silicon. Izinto ezidityanisiweyo ze-silicon-carbon zirekhodwe njenge-S1.
Izinto ze-silicon-carbon ezilungisiweyo i-S1 zifakwe uvavanyo lokuveliswa kwesiqingatha seseli kunye novavanyo lokukhupha itshaja. I-curve yokuqala yokukhupha itshaja iboniswe kuMfanekiso 5. Umthamo othile oguqukayo yi-1000.8 mAh/g, kwaye ukusebenza kakuhle komjikelo wokuqala kuphezulu njenge-93.9%, okungaphezulu kokusebenza kakuhle kokuqala kwezinto ezininzi ezisekwe kwi-silicon ngaphandle kwe-pre-lithiation echazwe kwiincwadi. Ukusebenza okuphezulu kokuqala kubonisa ukuba izinto ezidityanisiweyo ze-silicon-carbon zizinzile kakhulu. Ukuze kuqinisekiswe imiphumo yesakhiwo esineembobo, inethiwekhi yokuqhuba kunye nokufakwa kwekhabhoni ekuzinzeni kwezinto ze-silicon-carbon, iintlobo ezimbini zezinto ze-silicon-carbon zalungiswa ngaphandle kokongeza i-CNT kwaye ngaphandle kokufakwa kwekhabhoni yokuqala.
Imo yepowder eyenziwe ngekhabhoni yezinto ezidityanisiweyo zesilicon-carbon ngaphandle kokongeza i-CNT iboniswe kuMfanekiso 6. Emva kokugqunywa kwesigaba solwelo kunye nekhabhoni, umaleko wokugqunywa ungabonakala ngokucacileyo kumphezulu wee-particles zesibini kuMfanekiso 6(a). I-SEM yecandelo elinqamlezileyo lezinto ezidityanisiweyo iboniswe kuMfanekiso 6(b). Ukufakwa kwee-nanosheets ze-silicon kuneempawu ezidityanisiweyo, kwaye uvavanyo lwe-BET yi-16.6 m2/g. Nangona kunjalo, xa kuthelekiswa nemeko ye-CNT [njengoko kubonisiwe kuMfanekiso 3(d), uvavanyo lwe-BET lwepowder yayo eyenziwe ngekhabhoni yi-22.3 m2/g], uxinano lwangaphakathi lwe-nano-silicon stacking luphezulu, nto leyo ebonisa ukuba ukongezwa kwe-CNT kunokukhuthaza ukwakheka kwesakhiwo esidityanisiweyo. Ukongeza, izinto azinayo inethiwekhi yokuqhuba enemilinganiselo emithathu eyakhiwe yi-CNT. Izinto ezidityanisiweyo ze-silicon-carbon zirekhodwe njenge-S2.
Iimpawu zesimo sezinto ezidityanisiweyo ze-silicon-carbon ezilungiselelwe yi-carbon coating yesigaba esiqinileyo ziboniswe kuMfanekiso 7. Emva kwe-carbonization, kukho umaleko wokugquma ocacileyo phezu komphezulu, njengoko kubonisiwe kuMfanekiso 7(a). Umfanekiso 7(b) ubonisa ukuba kukho ii-nanoparticles ezimile njengemigca kwicandelo elinqamlezileyo, elihambelana neempawu zesimo se-nanosheets. Ukuqokelelana kwee-nanosheets kwenza isakhiwo esineembobo. Akukho sigcwalisi sicacileyo kumphezulu wee-nanosheets zangaphakathi, nto leyo ebonisa ukuba i-carbon coating yesigaba esiqinileyo yenza kuphela umaleko wokugquma we-carbon onesakhiwo esineembobo, kwaye akukho maleko wokugquma wangaphakathi wee-silicon nanosheets. Le nto idityanisiweyo ye-silicon-carbon irekhodwe njenge-S3.
Uvavanyo lwe-half-cell charge kunye ne-discharge lwenziwe kwi-S2 kunye ne-S3. Umthamo othile kunye nokusebenza kakuhle kokuqala kwe-S2 yayiyi-1120.2 mAh/g kunye ne-84.8%, ngokwahlukeneyo, kwaye umthamo othile kunye nokusebenza kakuhle kokuqala kwe-S3 yayiyi-882.5 mAh/g kunye ne-82.9%, ngokwahlukeneyo. Umthamo othile kunye nokusebenza kakuhle kokuqala kwesampulu ye-S3 egqunywe yi-solid-phase yayiyeyona iphantsi, nto leyo ebonisa ukuba kuphela uqweqwe lwekhabhoni lwesakhiwo esineembobo olwenziweyo, kwaye uqweqwe lwekhabhoni lwe-nanosheets zangaphakathi ze-silicon alwenziwanga, nto leyo eyayingenakukwazi ukunika amandla apheleleyo kwisixhobo esisekelwe kwi-silicon kwaye ayizange ikwazi ukukhusela umphezulu wesixhobo esisekelwe kwi-silicon. Ukusebenza kakuhle kokuqala kwesampulu ye-S2 ngaphandle kwe-CNT nako kwakuphantsi kunokwezinto ezidityanisiweyo ze-silicon-carbon eziqulethe i-CNT, nto leyo ebonisa ukuba ngokusekelwe komaleko olungileyo wokwaleka, inethiwekhi yokuqhuba kunye nenqanaba eliphezulu lesakhiwo esineembobo zinceda ekuphuculeni ukusebenza kakuhle kwetshaja kunye nokusebenza kakuhle kwesixhobo se-silicon-carbon.
Izinto ze-silicon-carbon ze-S1 zisetyenziselwe ukwenza ibhetri encinci ethambileyo epheleleyo ukuhlola ukusebenza kwesantya kunye nokusebenza komjikelo. I-curve yesantya sokukhupha iboniswe kuMfanekiso 8(a). Amandla okukhupha i-0.2C, 0.5C, 1C, 2C kunye ne-3C yi-2.970, 2.999, 2.920, 2.176 kunye ne-1.021 Ah, ngokwahlukeneyo. Amandla okukhupha i-1C aphezulu njenge-98.3%, kodwa izinga lokukhupha i-2C liyehla liye kwi-73.3%, kwaye izinga lokukhupha i-3C liyehla liye kwi-34.4%. Ukuze ujoyine iqela lokutshintshiselana nge-silicon negative electrode, nceda wongeze i-WeChat: shimobang. Ngokuphathelele izinga lokutshaja, amandla okutshaja e-0.2C, 0.5C, 1C, 2C kunye ne-3C yi-3.186, 3.182, 3.081, 2.686 kunye ne-2.289 Ah, ngokwahlukeneyo. Izinga lokutshaja le-1C liyi-96.7%, kwaye izinga lokutshaja le-2C lisafikelela kwi-84.3%. Nangona kunjalo, xa sijonga i-charging curve kuMfanekiso 8(b), iqonga lokutshaja le-2C likhulu kakhulu kuneqonga lokutshaja le-1C, kwaye amandla alo okutshaja e-constant voltage abandakanya uninzi (55%), nto leyo ebonisa ukuba i-polarisation yebhetri ye-2C etshajayo sele inkulu kakhulu. Izinto ze-silicon-carbon zisebenza kakuhle ekutshajeni nasekukhupheni kwi-1C, kodwa iimpawu zesakhiwo sezinto kufuneka ziphuculwe ngakumbi ukuze kufezekiswe ukusebenza okuphezulu. Njengoko kubonisiwe kuMfanekiso 9, emva kwemijikelo engama-450, izinga lokugcina amandla yi-78%, ebonisa ukusebenza kakuhle kwemijikelo.
Imeko yomphezulu we-electrode ngaphambi nasemva komjikelo iphandwe yi-SEM, kwaye iziphumo ziboniswe kuMfanekiso 10. Ngaphambi komjikelo, umphezulu we-graphite kunye nezinto ze-silicon-carbon ucacile [Umfanekiso 10(a)]; emva komjikelo, umaleko wokugquma uyabonakala ukuba uvela kumphezulu [Umfanekiso 10(b)], oyifilimu etyebileyo ye-SEI. Uburhabaxa befilimu ye-SEI Ukusetyenziswa kwe-lithium esebenzayo kuphezulu, okungahambelaniyo nokusebenza komjikelo. Ke ngoko, ukukhuthaza ukwenziwa kwefilimu ye-SEI egudileyo (njengokwakhiwa kwefilimu ye-SEI yokwenziwa, ukongeza izongezo ze-electrolyte ezifanelekileyo, njl.njl.) kunokuphucula ukusebenza komjikelo. Ukujongwa kwe-SEM yecandelo elinqamlezileyo lamasuntswana e-silicon-carbon emva komjikelo [Umfanekiso 10(c)] ubonisa ukuba ii-nanoparticles ze-silicon ezimile njenge-strip ziye zaba nzima kwaye isakhiwo se-porous sisusiwe ngokusisiseko. Oku kungenxa yokwanda okuqhubekayo komthamo kunye nokucutheka kwezinto ze-silicon-carbon ngexesha lomjikelo. Ke ngoko, isakhiwo se-porous kufuneka siphuculwe ngakumbi ukubonelela ngendawo eyaneleyo ye-buffer yokwandiswa komthamo wezinto ezisekwe kwi-silicon.
3 Isiphelo
Ngokusekelwe ekwandeni komthamo, ukuqhuba kakubi kombane kunye nokuzinza okungalunganga kojongano lwezinto ze-electrode ezingasebenziyo ezisekelwe kwi-silicon, eli phepha lenza uphuculo olujoliswe kulo, ukusuka ekubunjweni kwe-morphology yee-nanosheets ze-silicon, ukwakhiwa kwesakhiwo esine-porous, ukwakhiwa kwenethiwekhi yokuqhuba kunye nokufakwa ngokupheleleyo kwekhabhoni kwamasuntswana esibini, ukuphucula ukuzinza kwezinto ze-electrode ezingasebenziyo ezisekelwe kwi-silicon iyonke. Ukuqokelelwa kwee-nanosheets ze-silicon kunokwenza isakhiwo esine-porous. Ukungeniswa kwe-CNT kuya kukhuthaza ngakumbi ukwakheka kwesakhiwo esine-porous. Izinto ezidityanisiweyo ze-silicon-carbon ezilungiselelwe nge-liquid phase coating zinefuthe lokugquma kabini kunezo zilungiselelwe yi-solid phase coating, kwaye zibonisa amandla athile aphezulu kunye nokusebenza kakuhle kokuqala. Ukongeza, ukusebenza kakuhle kokuqala kwezinto ezidityanisiweyo ze-silicon-carbon eziqulethe i-CNT kuphezulu kunoko ngaphandle kwe-CNT, okubangelwa ikakhulu kubuchule obuphezulu besakhiwo esine-porous bokunciphisa ukwanda komthamo wezinto ezisekelwe kwi-silicon. Ukungeniswa kwe-CNT kuya kwakha inethiwekhi yokuqhuba enemilinganiselo emithathu, kuphucule ukuqhuba kakuhle kwezixhobo ezisekelwe kwi-silicon, kwaye kubonise ukusebenza okuhle kwesantya kwi-1C; kwaye izinto zibonisa ukusebenza kakuhle komjikelo. Nangona kunjalo, ulwakhiwo olunemingxuma yezinto kufuneka luqiniswe ngakumbi ukuze kubonelelwe ngendawo eyaneleyo yokwandisa umthamo we-silicon, kwaye kukhuthazwe ukwakheka komoya ogudileyo.kunye nefilimu ye-SEI exineneyo ukuphucula ngakumbi ukusebenza komjikelo wezinto ezidityanisiweyo ze-silicon-carbon.
Sikwabonelela ngeemveliso zegrafiti kunye ne-silicon carbide ezicocekileyo kakhulu, ezisetyenziswa kakhulu ekucubunguleni i-wafer efana ne-oxidation, diffusion, kunye ne-annealing.
Wamkelekile nabathengi abavela kwihlabathi liphela ukuba basityelele ukuze sixoxe ngakumbi!
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Ixesha leposi: Novemba-13-2024