Amabhethri e-lithium-ion athuthuka kakhulu ngokuya ngamandla aphezulu. Ezingeni lokushisa legumbi, izinto ze-electrode ezingembi ezisekelwe ku-silicon zihlanganiswa ne-lithium ukukhiqiza umkhiqizo we-lithium-rich Li3.75Si phase, onekhono elithile elingafika ku-3572 mAh/g, eliphakeme kakhulu kunomthamo othize we-graphite negative electrode engu-372 mAh/g. Kodwa-ke, ngesikhathi senqubo yokushaja nokukhipha okuphindaphindiwe kwezinto ze-electrode ezingembi ezisekelwe ku-silicon, ukuguqulwa kwesigaba se-Si ne-Li3.75Si kungakhiqiza ukwanda okukhulu kwevolumu (cishe ngo-300%), okuzoholela ekufakweni kwe-powder kwesakhiwo kwezinto ze-electrode kanye nokwakheka okuqhubekayo kwefilimu ye-SEI, futhi ekugcineni kubangele ukuthi amandla ehle ngokushesha. Imboni ithuthukisa kakhulu ukusebenza kwezinto ze-electrode ezingembi ezisekelwe ku-silicon kanye nokuzinza kwamabhethri asekelwe ku-silicon ngokusebenzisa ubukhulu be-nano, i-carbon coating, ukwakheka kwama-pore kanye nobunye ubuchwepheshe.
Izinto zekhabhoni zinokuqhuba kahle komoya, izindleko eziphansi, kanye nemithombo ebanzi. Zingathuthukisa ukuqhutshwa komoya kanye nokuqina kobuso bezinto ezisekelwe ku-silicon. Zisetshenziswa ngokukhethekile njengezithasiselo zokuthuthukisa ukusebenza kwama-electrode angemihle asekelwe ku-silicon. Izinto ze-silicon-carbon ziyisiqondiso esiyinhloko sokuthuthukiswa kwama-electrode angemihle asekelwe ku-silicon. Ukugqoka kwekhabhoni kungathuthukisa ukuzinza kobuso bezinto ezisekelwe ku-silicon, kodwa ikhono layo lokuvimbela ukwanda komthamo we-silicon livamile futhi alikwazi ukuxazulula inkinga yokwanda komthamo we-silicon. Ngakho-ke, ukuze kuthuthukiswe ukuzinza kwezinto ezisekelwe ku-silicon, izakhiwo ezinezimbobo kudingeka zakhiwe. Ukugaya ibhola kuyindlela yezimboni yokulungiselela izinto ze-nanomaterials. Izithasiselo ezahlukene noma izingxenye zezinto zingafakwa ku-slurry etholakala ngokugaya ibhola ngokwezidingo zomklamo wezinto ezihlanganisiwe. I-slurry isakazwa ngokulinganayo ngama-slurry ahlukahlukene bese yomiswa nge-spray. Ngesikhathi senqubo yokomisa ngokushesha, ama-nanoparticles nezinye izingxenye ku-slurry zizokwakha izici zesakhiwo ezinezimbobo ngokuzenzakalelayo. Leli phepha lisebenzisa ubuchwepheshe bokugaya ibhola obusezingeni eliphezulu nobunobungani nemvelo kanye nokomisa nge-spray ukulungiselela izinto ezisekelwe ku-silicon ezinezimbobo.
Ukusebenza kwezinto ezisekelwe ku-silicon kungathuthukiswa ngokulawula isimo sezinto kanye nezici zokusatshalaliswa kwezinto ezisetshenziswa ku-silicon nanomaterials. Njengamanje, izinto ezisekelwe ku-silicon ezinezinhlobo ezahlukene zezinto kanye nezici zokusatshalaliswa sezilungisiwe, njenge-silicon nanorods, i-porous graphite embedded nanosilicon, i-nanosilicon esatshalaliswa kuma-carbon sphere, izakhiwo ezinamaphiko ze-silicon/graphene array, njll. Ngesilinganiso esifanayo, uma kuqhathaniswa nezinhlayiya ezincane, ama-nanosheet angacindezela kangcono inkinga yokuchotshozwa ebangelwa ukwanda kwevolumu, futhi izinto zinobuningi obukhulu bokuxinana. Ukufakwa okungahlelekile kwama-nanosheet nakho kungakha isakhiwo esinamaphiko. Ukujoyina iqembu lokushintshana kwe-silicon negative electrode. Nikeza isikhala se-buffer sokwandiswa kwevolumu yezinto ezisetshenziswa ku-silicon. Ukwethulwa kwama-carbon nanotubes (ama-CNT) akugcini nje ngokuthuthukisa ukuhanjiswa kwezinto, kodwa futhi kukhuthaze ukwakheka kwezakhiwo ezinamaphiko zezinto ngenxa yezici zayo zesimo se-single-dimensional. Azikho imibiko ngezakhiwo ezinamaphiko ezakhiwe ama-silicon nanosheet nama-CNT. Leli phepha lisebenzisa indlela yokugaya ibhola, ukugaya nokusabalalisa ezimbonini, ukomisa nge-spray, izindlela zokufaka i-carbon pre-coating kanye ne-calcination, futhi lethula abagqugquzeli be-porous enqubweni yokulungiselela ukulungiselela izinto ze-electrode ezi-negative ezisekelwe ku-silicon ezimboziwe ezakhiwe ngokuzihlanganisa kwama-silicon nanosheets nama-CNT. Inqubo yokulungiselela ilula, inobungani nemvelo, futhi akukho uketshezi olungcolile noma insalela yemfucuza ekhiqizwayo. Kunemibiko eminingi yezincwadi mayelana nokufakwa kwe-carbon kwezinto ezisekelwe ku-silicon, kodwa kunezingxoxo ezimbalwa ezijulile ngomphumela wokufakwa kwe-coating. Leli phepha lisebenzisa i-asphalt njengomthombo we-carbon ukuphenya imiphumela yezindlela ezimbili zokufakwa kwe-carbon, ukufakwa kwe-liquid phase kanye nokufakwa kwe-solid phase, kumphumela wokufakwa kwe-coating kanye nokusebenza kwezinto ze-electrode ezisekelwe ku-silicon.
1 Ukuhlolwa
1.1 Ukulungiselela izinto
Ukulungiswa kwezinto ezihlanganisiwe ze-silicon-carbon ezinezimbobo kuhlanganisa kakhulu izinyathelo ezinhlanu: ukugaya ibhola, ukugaya nokusabalalisa, ukomisa nge-spray, ukufaka i-carbon pre-coating kanye ne-carbonization. Okokuqala, kala u-500 g wempuphu ye-silicon yokuqala (yasekhaya, ubumsulwa obungu-99.99%), engeza u-2000 g we-isopropanol, bese wenza ukugaya ibhola okumanzi ngesivinini sokugaya ibhola esingu-2000 r/min amahora angama-24 ukuze uthole i-silicon slurry enama-nano-scale. I-silicon slurry etholakele idluliselwa ethangini lokudlulisa ukuhlakazeka, futhi izinto zengezwa ngokwesilinganiso sobuningi be-silicon: i-graphite (ekhiqizwa eShanghai, ibanga lebhethri): ama-carbon nanotubes (akhiqizwa eTianjin, ibanga lebhethri): i-polyvinyl pyrrolidone (ekhiqizwa eTianjin, ibanga lokuhlaziya) = 40:60:1.5:2. I-Isopropanol isetshenziselwa ukulungisa okuqukethwe okuqinile, futhi okuqukethwe okuqinile kuklanyelwe ukuba ngu-15%. Ukugaya nokuhlakazeka kwenziwa ngesivinini sokuhlakazeka esingu-3500 r/min amahora ama-4. Elinye iqembu lama-slurry ngaphandle kokufaka ama-CNT liyaqhathaniswa, kanti ezinye izinto ziyafana. I-slurry ehlakazekile etholakele ibe isidluliselwa ethangini lokudla lokomisa ngokufutha, bese ukomisa ngokufutha kwenziwa endaweni evikelwe yi-nitrogen, kanti amazinga okushisa okungena nokuphuma angu-180 no-90 °C, ngokulandelana. Kwabe sekuqhathaniswa izinhlobo ezimbili ze-carbon coating, i-solid phase coating kanye ne-liquid phase coating. Indlela ye-solid phase coating yile: i-powder eyomisiwe ngokufutha ixutshwa ne-20% asphalt powder (eyenziwe eKorea, i-D50 ingu-5 μm), ixutshwe ku-mechanical mixer imizuzu eyi-10, kanti isivinini sokuxuba singama-2000 r/min ukuthola i-pre-coated powder. Indlela ye-liquid phase coating yile: i-powder eyomisiwe ngokufutha ingezwa kwisisombululo se-xylene (eyenziwe eTianjin, ibanga lokuhlaziya) equkethe i-20% asphalt encibilikisiwe ku-powder ngokuqukethwe okuqinile okungu-55%, bese i-vacuum ivuselelwa ngokulinganayo. Bhaka kuhhavini ongenalutho ku-85℃ amahora ama-4, ufake kumshini wokuxuba osebenza ngomshini ukuze uxube, isivinini sokuxuba singama-2000 r/min, kanti isikhathi sokuxuba singama-10 min ukuthola i-powder efakwe ngaphambili. Ekugcineni, i-powder efakwe ngaphambili yafakwa kuhhavini ojikelezayo ngaphansi kwesimo sezulu se-nitrogen ngesilinganiso sokushisa esingu-5°C/min. Yaqala yagcinwa ekushiseni okungaguquki okungu-550°C amahora ama-2, yabe isiqhubeka nokushisa kufika ku-800°C futhi yagcinwa ekushiseni okungaguquki amahora ama-2, yabe isipholiswa ngokwemvelo ibe ngaphansi kuka-100°C bese ikhishwa ukuze kutholakale izinto ezihlanganisiwe ze-silicon-carbon.
1.2 Izindlela zokubhala izinhlamvu
Ukusatshalaliswa kosayizi wezinhlayiya zezinto kwahlaziywa kusetshenziswa umhloli wosayizi wezinhlayiya (inguqulo ye-Mastersizer 2000, eyenziwe e-UK). Izinhlayiya ezitholwe esinyathelweni ngasinye zahlolwa ngokuskena i-electron microscopy (Regulus8220, eyenziwe eJapan) ukuhlola isimo nosayizi wezinhlayiya. Isakhiwo sesigaba sezinto sahlaziywa kusetshenziswa i-X-ray powder diffraction analyzer (D8 ADVANCE, eyenziwe eJalimane), kanti ukwakheka kwezinto kwahlaziywa kusetshenziswa i-energy spectrum analyzer. Izinto ezihlanganisiwe ze-silicon-carbon ezitholwe zasetshenziswa ukwenza inkinobho yesigamu-seli semodeli ye-CR2032, kanye nesilinganiso sobuningi be-silicon-carbon: SP: CNT: CMC: SBR sasingu-92:2:2:1.5:2.5. I-electrode yekhawuntara iyishidi le-lithium lensimbi, i-electrolyte iyi-electrolyte yezentengiselwano (imodeli 1901, eyenziwe eKorea), kusetshenziswa i-diaphragm ye-Celgard 2320, ububanzi be-voltage yokushaja nokukhipha buyi-0.005-1.5 V, i-charge nokukhipha ugesi kungu-0.1 C (1C = 1A), kanti i-discharge cut-off current ingu-0.05 C.
Ukuze kuqhutshekwe nokuphenywa kokusebenza kwezinto ezihlanganisiwe ze-silicon-carbon, kwenziwa ibhethri elincane elithambile elinomshini wokunamathisela i-laminated 408595. I-electrode enhle isebenzisa i-NCM811 (eyenziwe eHunan, ibanga lebhethri), kanti i-graphite ye-electrode engemihle ifakwe izinto ze-silicon-carbon ezingu-8%. Ifomula ye-slurry ye-electrode enhle ingu-96% NCM811, i-1.2% polyvinylidene fluoride (PVDF), i-2% conductive agent SP, i-0.8% CNT, kanti i-NMP isetshenziswa njengesihlanzi; ifomula ye-slurry ye-electrode engemihle ingu-96% wezinto ezihlanganisiwe ze-electrode engemihle, i-1.3% CMC, i-1.5% SBR 1.2% CNT, kanti amanzi asetshenziswa njengesihlanzi. Ngemva kokuxubha, ukumboza, ukugoqa, ukusika, ukunamathisela, ukushisela amathebhu, ukupakisha, ukubhaka, ukujova uketshezi, ukwakheka kanye nokwahlukaniswa kwamandla, kwalungiswa amabhethri e-soft pack amancane angu-408595 anomthamo olinganiselwe ongu-3 Ah. Ukusebenza kwezinga lika-0.2C, 0.5C, 1C, 2C kanye no-3C kanye nokusebenza komjikelezo wokushaja okungu-0.5C kanye nokukhishwa okungu-1C kuhlolwe. Ububanzi be-voltage yokushaja kanye nokukhishwa kwakungu-2.8-4.2 V, ukushaja kwamanje okungaguquki kanye nokukhishwa kwamanje okungaguquki, kanye nomshini wokusika kwakungu-0.5C.
2 Imiphumela kanye nengxoxo
Impuphu ye-silicon yokuqala yabonwa ngokuskena i-electron microscopy (SEM). Impuphu ye-silicon yayingajwayelekile ngosayizi wezinhlayiya ezingaphansi kuka-2μm, njengoba kuboniswe kuMfanekiso 1(a). Ngemva kokugaya ibhola, usayizi wempuphu ye-silicon wehliswa kakhulu waba cishe yi-100 nm [Isithombe 1(b)]. Ukuhlolwa kosayizi wezinhlayiya kubonise ukuthi i-D50 yempuphu ye-silicon ngemuva kokugaya ibhola yayingu-110 nm kanti i-D90 yayingu-175 nm. Ukuhlolwa ngokucophelela kwesimo sempuphu ye-silicon ngemuva kokugaya ibhola kukhombisa isakhiwo esiqhekekile (ukwakheka kwesakhiwo esiqhekekile kuzoqinisekiswa kabanzi kusukela ku-SEM enqamulayo kamuva). Ngakho-ke, idatha ye-D90 etholwe ekuhlolweni kosayizi wezinhlayiya kufanele ibe ubukhulu bobude be-nanosheet. Uma ihlanganiswe nemiphumela ye-SEM, kungahlulelwa ukuthi usayizi we-nanosheet etholiwe uncane kunenani elibalulekile lika-150 nm lokuphuka kwempuphu ye-silicon ngesikhathi sokushaja nokukhipha okungenani ubukhulu obulodwa. Ukwakheka kokwakheka okuqhekekile kungenxa yamandla ahlukene okuhlukaniswa kwezindiza zekristalu ze-silicon ekristalu, phakathi kwazo indiza ye-silicon {111} enamandla okuhlukaniswa aphansi kunezindiza zekristalu {100} kanye {110}. Ngakho-ke, le ndiza yekristalu incishiswa kalula ngokugaya ibhola, futhi ekugcineni yakha isakhiwo esiqhekekile. Isakhiwo esiqhekekile sivumela ukuqongelela kwezakhiwo ezikhululekile, sigcina isikhala sokwanda kwevolumu ye-silicon, futhi sithuthukisa ukuzinza kwezinto.
I-slurry equkethe i-nano-silicon, i-CNT kanye ne-graphite yafuthwa, kanti i-powder ngaphambi nangemva kokufuthwa yahlolwa yi-SEM. Imiphumela iboniswe ku-Figure 2. I-graphite matrix engezwe ngaphambi kokufuthwa iyisakhiwo esijwayelekile se-flake esinobukhulu obungu-5 kuya ku-20 μm [Isithombe 2(a)]. Ukuhlolwa kokusabalalisa kosayizi wezinhlayiya ze-graphite kukhombisa ukuthi i-D50 ingu-15μm. I-powder etholwe ngemva kokufuthwa inokwakheka okuyisiyingi [Isithombe 2(b)], futhi kungabonakala ukuthi i-graphite imbozwe ungqimba lokumboza ngemva kokufuthwa. I-D50 ye-powder ngemva kokufuthwa ingu-26.2 μm. Izici ze-morphological zezinhlayiya zesibili zabonwa yi-SEM, zibonisa izici zesakhiwo esikhululekile esinezimbobo esiqoqwe yi-nanomaterials [Isithombe 2(c)]. Isakhiwo esinezimbobo sakhiwe ngama-silicon nanosheets nama-CNT axhumene [Isithombe 2(d)], kanti indawo ethile yokuhlola (i-BET) iphakeme njengo-53.3 m2/g. Ngakho-ke, ngemva kokufutha, ama-silicon nanosheet nama-CNT ayazihlanganisa ukuze akhe isakhiwo esinezimbobo.
Ingqimba enezimbobo iphathwe nge-liquid carbon coating, kwathi ngemva kokufaka i-carbon coating precursor pitch kanye ne-carbonization, kwenziwa ukubonwa kwe-SEM. Imiphumela iboniswe ku-Figure 3. Ngemva kwe-carbon pre-coating, ubuso bezinhlayiya zesibili buba bushelelezi, ngengqimba yokumboza esobala, futhi i-coating iphelele, njengoba kuboniswe ku-Figures 3(a) kanye no-(b). Ngemva kwe-carbonization, ingqimba yokumboza ebusweni igcina isimo esihle sokumboza [Figure 3(c)]. Ngaphezu kwalokho, isithombe se-SEM esinqamulelayo sibonisa ama-nanoparticles anomucu [Figure 3(d)], ahambisana nezici ze-morphological zama-nanosheet, okuqinisekisa ukwakheka kwama-silicon nanosheet ngemva kokugaya ibhola. Ngaphezu kwalokho, i-Figure 3(d) ikhombisa ukuthi kukhona ama-filler phakathi kwamanye ama-nanosheet. Lokhu kungenxa yokusetshenziswa kwendlela yokumboza yesigaba soketshezi. Isixazululo se-asphalt sizongena ezintweni, ukuze ubuso bama-silicon nanosheet angaphakathi buthole ingqimba yokuvikela ye-carbon coating. Ngakho-ke, ngokusebenzisa i-liquid phase coating, ngaphezu kokuthola umphumela we-secondary particle coating, umphumela we-double carbon coating we-primary particle coating nawo ungatholakala. I-carbonized powder ihlolwe yi-BET, futhi umphumela wokuhlolwa wawungu-22.3 m2/g.
Impuphu ekhabhoniwe yahlolwa nge-cross-sectional energy spectrum (EDS), futhi imiphumela iboniswe ku-Figure 4(a). I-core enobukhulu be-micron iyi-C component, ehambisana ne-graphite matrix, kanti i-coating yangaphandle iqukethe i-silicon ne-oxygen. Ukuze kuhlolwe kabanzi ngesakhiwo se-silicon, kwenziwa ukuhlolwa kwe-X-ray diffraction (XRD), futhi imiphumela iboniswe ku-Figure 4(b). Izinto zokwakha zakhiwe kakhulu nge-graphite ne-single-crystal silicon, ezingenazo izici ezicacile ze-silicon oxide, okubonisa ukuthi ingxenye ye-oxygen yokuhlolwa kwe-energy spectrum ivela kakhulu ekushiseni kwemvelo kobuso be-silicon. Izinto ezihlanganisiwe ze-silicon-carbon ziqoshwe njenge-S1.
Izinto ze-silicon-carbon ezilungisiwe i-S1 zihlolwe ukukhiqizwa kweseli eliyi-button-type kanye nokuhlolwa kokukhishwa kweshaja. Ijika lokuqala lokukhishwa kweshaja liboniswe ku-Figure 5. Umthamo othize oguquguqukayo ungu-1000.8 mAh/g, kanti ukusebenza kahle komjikelezo wokuqala kuphakeme njengo-93.9%, okuphakeme kunokusebenza kahle kokuqala kwezinto eziningi ezisekelwe ku-silicon ngaphandle kwe-pre-lithiation ebikwe ezincwadini. Ukusebenza kahle kokuqala okuphezulu kubonisa ukuthi izinto ezihlanganisiwe ze-silicon-carbon ezilungisiwe zinokuzinza okuphezulu. Ukuze kuqinisekiswe imiphumela yesakhiwo esinezimbobo, inethiwekhi eqhubayo kanye nokuhlanganiswa kwe-carbon ekuzinzeni kwezinto ze-silicon-carbon, izinhlobo ezimbili zezinto ze-silicon-carbon zalungiswa ngaphandle kokwengeza i-CNT futhi ngaphandle kokuhlanganiswa kwe-carbon okuyinhloko.
Ukwakheka kwempuphu ekhabhoni yezinto ezihlanganisiwe ze-silicon-carbon ngaphandle kokwengeza i-CNT kukhonjisiwe kuMfanekiso 6. Ngemva kokumbozwa kwesigaba soketshezi kanye nokufakwa kwe-carbon, ungqimba lokumboza lungabonakala ngokucacile ebusweni bezinhlayiya zesibili kuMfanekiso 6(a). I-SEM yesigaba esinqamulelayo sezinto ezihlanganisiwe iboniswe kuMfanekiso 6(b). Ukufakwa kwama-nanosheet e-silicon kunezici ezimbozwayo, kanti ukuhlolwa kwe-BET kungu-16.6 m2/g. Kodwa-ke, uma kuqhathaniswa necala le-CNT [njengoba kuboniswe kuMfanekiso 3(d), ukuhlolwa kwe-BET kwempuphu yayo ekhabhoni kungu-22.3 m2/g], ubuningi bokufakwa kwe-nano-silicon buphakeme, okubonisa ukuthi ukungezwa kwe-CNT kungakhuthaza ukwakheka kwesakhiwo esimbozwayo. Ngaphezu kwalokho, izinto azinayo inethiwekhi yokuqhuba enezinhlangothi ezintathu eyakhiwe yi-CNT. Izinto ezihlanganisiwe ze-silicon-carbon ziqoshwe njenge-S2.
Izici zesimo sezinto ezihlanganisiwe ze-silicon-carbon ezilungiselelwe yi-solid-phase carbon coating ziboniswe ku-Figure 7. Ngemva kwe-carbonization, kukhona ungqimba olubonakalayo lwe-coating ebusweni, njengoba kuboniswe ku-Figure 7(a). I-Figure 7(b) ikhombisa ukuthi kunezinhlayiya ezincane ezimise okwemicu esigabeni esiphambeneyo, okuhambisana nezici ze-morphological zama-nanosheet. Ukuqongelela kwama-nanosheet kwakha isakhiwo esinezimbobo. Akukho okugcwala okusobala ebusweni bama-nanosheet angaphakathi, okubonisa ukuthi i-solid-phase carbon coating yakha kuphela ungqimba lwe-carbon coating olunesakhiwo esinezimbobo, futhi akukho ungqimba lwangaphakathi lwe-silicon nanosheet. Le nto ehlanganisiwe ye-silicon-carbon iqoshwe njenge-S3.
Ukuhlolwa kokushaja kwesigamu seseli kanye nokukhishwa kwegesi kwenziwa ku-S2 naku-S3. Umthamo othize kanye nokusebenza kahle kokuqala kwe-S2 kwakungu-1120.2 mAh/g kanye no-84.8%, ngokulandelana, kanti umthamo othize kanye nokusebenza kahle kokuqala kwe-S3 kwakungu-882.5 mAh/g kanye no-82.9%, ngokulandelana. Umthamo othize kanye nokusebenza kahle kokuqala kwesampula ye-S3 eboshwe ngesigaba esiqinile kwakuyinto ephansi kakhulu, okubonisa ukuthi kuphela ukuhlanganiswa kwekhabhoni kwesakhiwo esinezimbobo okwenziwe, kanti ukuhlanganiswa kwekhabhoni kwama-nanosheet e-silicon angaphakathi akwenziwanga, okwakungakwazi ukunikeza ukudlala okugcwele kumthamo othize wezinto ezisekelwe ku-silicon futhi kwakungenakuvikela ubuso bezinto ezisekelwe ku-silicon. Ukusebenza kahle kokuqala kwesampula ye-S2 ngaphandle kwe-CNT nakho kwakuphansi kunokwezinto ezihlanganisiwe ze-silicon-carbon eziqukethe i-CNT, okubonisa ukuthi ngesisekelo sesendlalelo esihle sokufaka, inethiwekhi yokuhambisa kanye nezinga eliphakeme lesakhiwo esinezimbobo kusiza ekuthuthukiseni ukusebenza kahle kokushaja kanye nokukhishwa kwento ye-silicon-carbon.
Izinto ze-S1 silicon-carbon zasetshenziswa ukwenza ibhethri elincane eligcwele iphakethe elithambile ukuhlola ukusebenza kwezinga kanye nokusebenza komjikelezo. Ijika lezinga lokukhipha liboniswe kuMfanekiso 8(a). Amandla okukhipha angu-0.2C, 0.5C, 1C, 2C kanye no-3C angama-2.970, 2.999, 2.920, 2.176 kanye no-1.021 Ah, ngokulandelana. Izinga lokukhipha elingu-1C liphezulu njengo-98.3%, kodwa izinga lokukhipha elingu-2C lehla laya ku-73.3%, kanti izinga lokukhipha elingu-3C lehla laya ku-34.4%. Ukuze ujoyine iqembu lokushintshana kwe-silicon negative electrode, sicela ungeze i-WeChat: shimobang. Ngokuphathelene nezinga lokushaja, amandla okushaja angu-0.2C, 0.5C, 1C, 2C kanye no-3C angama-3.186, 3.182, 3.081, 2.686 kanye no-2.289 Ah, ngokulandelana. Izinga lokushaja le-1C lingu-96.7%, kanti izinga lokushaja le-2C lisafinyelela ku-84.3%. Kodwa-ke, uma sibheka ijika lokushaja kuMfanekiso 8(b), ipulatifomu yokushaja ye-2C inkulu kakhulu kunepulatifomu yokushaja ye-1C, futhi umthamo wayo wokushaja we-voltage engaguquki ubalwa kakhulu (55%), okubonisa ukuthi i-polarization yebhethri elishajayo le-2C selivele likhulu kakhulu. Izinto ze-silicon-carbon zinokusebenza okuhle kokushaja nokukhipha ku-1C, kodwa izici zesakhiwo sezinto zidinga ukuthuthukiswa ukuze kufezwe ukusebenza okuphezulu kwezinga. Njengoba kuboniswe kuMfanekiso 9, ngemva kwemijikelezo engu-450, izinga lokugcina umthamo lingu-78%, okubonisa ukusebenza okuhle komjikelezo.
Isimo sobuso be-electrode ngaphambi nangemva komjikelezo sihlolwe yi-SEM, futhi imiphumela iboniswe kuMfanekiso 10. Ngaphambi komjikelezo, ubuso bezinto ze-graphite kanye ne-silicon-carbon bucacile [Isithombe 10(a)]; ngemva komjikelezo, kusobala ukuthi kukhiqizwa ungqimba lokumboza phezu kobuso [Isithombe 10(b)], okuyifilimu ejiyile ye-SEI. Ubulukhuni befilimu ye-SEI Ukusetshenziswa kwe-lithium esebenzayo kuphezulu, okungavumeli ukusebenza komjikelezo. Ngakho-ke, ukukhuthaza ukwakheka kwefilimu ye-SEI ebushelelezi (njengokwakhiwa kwefilimu ye-SEI yokwenziwa, ukwengeza izithasiselo ze-electrolyte ezifanele, njll.) kungathuthukisa ukusebenza komjikelezo. Ukubonwa kwe-SEM kwezingxenye ze-silicon-carbon izinhlayiya ngemva komjikelezo [Isithombe 10(c)] kukhombisa ukuthi izinhlayiya ze-silicon nanoparticles zokuqala ezimise okwesiqeshana sezibe ziqinile futhi isakhiwo esinezimbobo sesisusiwe ngokuyisisekelo. Lokhu kungenxa yokwanda okuqhubekayo kwevolumu kanye nokufinyela kwezinto ze-silicon-carbon phakathi nomjikelezo. Ngakho-ke, isakhiwo esinezimbobo sidinga ukuthuthukiswa ukuze kunikezwe isikhala esanele se-buffer sokwandiswa kwevolumu kwezinto ezisekelwe ku-silicon.
3 Isiphetho
Ngokusekelwe ekunwetshweni kwevolumu, ukuhanjiswa kwegesi okungekuhle kanye nokuqina kwesikhombikubona okungekuhle kwezinto ze-electrode ezingekuhle ezisekelwe ku-silicon, leli phepha lenza ukuthuthuka okuqondiwe, kusukela ekubunjweni kwe-silicon nanosheets, ukwakhiwa kwesakhiwo esinezimbobo, ukwakhiwa kwenethiwekhi yokuhambisa umoya kanye nokufakwa kwe-carbon okuphelele kwezinhlayiya zesibili, ukuthuthukisa ukuzinza kwezinto ze-electrode ezingekuhle ezisekelwe ku-silicon iyonke. Ukuqongelela kwama-silicon nanosheets kungakha isakhiwo esinezimbobo. Ukwethulwa kwe-CNT kuzothuthukisa ukwakheka kwesakhiwo esinezimbobo. Izinto ezihlanganisiwe ze-silicon-carbon ezilungiselelwe nge-liquid phase coating zinomphumela wokumboza we-carbon kabili kunalowo olungiselelwe nge-solid phase coating, futhi zibonisa amandla athile aphezulu kanye nokusebenza kahle kokuqala. Ngaphezu kwalokho, ukusebenza kahle kokuqala kwezinto ezihlanganisiwe ze-silicon-carbon eziqukethe i-CNT kuphakeme kunalokho okungenazo i-CNT, okubangelwa kakhulu izinga eliphezulu lekhono lesakhiwo esinezimbobo lokunciphisa ukwanda kwevolumu yezinto ezisekelwe ku-silicon. Ukwethulwa kwe-CNT kuzokwakha inethiwekhi yokuhambisa umoya enezinhlangothi ezintathu, kuthuthukise ukuhanjiswa kwegesi kwezinto ezisekelwe ku-silicon, futhi kubonise ukusebenza okuhle kwesilinganiso ku-1C; futhi izinto zibonisa ukusebenza okuhle komjikelezo. Kodwa-ke, isakhiwo sezinto ezinezimbobo sidinga ukuqiniswa ngokwengeziwe ukuze kunikezwe isikhala esanele sokwandisa umthamo we-silicon, futhi kukhuthazwe ukwakheka komoya obushelelezi.kanye nefilimu ye-SEI ebanzi ukuze kuthuthukiswe ukusebenza komjikelezo wezinto ezihlanganisiwe ze-silicon-carbon.
Siphinde sinikeze imikhiqizo ye-graphite ne-silicon carbide ehlanzekile kakhulu, esetshenziswa kabanzi ekucubungulweni kwe-wafer njenge-oxidation, diffusion, kanye ne-annealing.
Yamukela noma yimaphi amakhasimende avela emhlabeni wonke ukuthi asivakashele ukuze sixoxe kabanzi!
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Isikhathi sokuthunyelwe: Novemba-13-2024