Amabhethri e-lithium-ion athuthuka kakhulu ekuqondeni kwamandla aphezulu. Ezingeni lokushisa lasekamelweni, i-silicon-based negative electrode materials alloy ene-lithium ukukhiqiza umkhiqizo ocebile we-lithium Li3.75Si isigaba, esinamandla athile afinyelela ku-3572 mAh/g, ephakeme kakhulu kunomthamo othize wethiyori we-graphite negative electrode 372. mAh/g. Kodwa-ke, phakathi nenqubo yokushaja nokukhipha okuphindaphindiwe kwezinto ze-electrode negative ezisekelwe ku-silicon, ukuguqulwa kwesigaba se-Si ne-Li3.75Si kungaveza ukunwetshwa kwevolumu enkulu (cishe ngo-300%), okuzoholela ekwenzeni impushana yesakhiwo sezinto ze-electrode kanye nokwakheka okuqhubekayo Ifilimu ye-SEI, futhi ekugcineni ibangele amandla ehla ngokushesha. Imboni ikakhulukazi ithuthukisa ukusebenza kwe-silicon-based negative electrode materials kanye nokuzinza kwamabhethri asekelwe ku-silicon ngokusebenzisa i-nano-size, i-carbon coating, ukwakheka kwama-pore nobunye ubuchwepheshe.
Izinto zekhabhoni zine-conductivity enhle, izindleko eziphansi, nemithombo ebanzi. Bangakwazi ukuthuthukisa i-conductivity kanye nokuzinza kwendawo yezinto ezisekelwe ku-silicon. Zisetshenziswa ngokukhethekile njengezithasiselo zokuthuthukisa ukusebenza kwama-electrode amabi asuselwa ku-silicon. Izinto ze-silicon-carbon ziyizikhombisi-ndlela zokuthuthukiswa ezijwayelekile zama-electrode angalungile asuselwa ku-silicon. I-carbon coating ingathuthukisa ukuzinza kwendawo yezinto ezisekelwe ku-silicon, kodwa ikhono layo lokuvimbela ukunwetshwa kwevolumu ye-silicon lijwayelekile futhi alikwazi ukuxazulula inkinga yokwanda kwevolumu ye-silicon. Ngakho-ke, ukuze kuthuthukiswe ukuzinza kwezinto ezisekelwe ku-silicon, izakhiwo ezinama-porous zidinga ukwakhiwa. Ukugaywa kwebhola kuyindlela ethuthukisiwe yokulungiselela ama-nanomaterials. Izithasiselo ezahlukene noma izingxenye zempahla zingangezwa ku-slurry etholwe ngokugaywa kwebhola ngokuvumelana nezidingo zokuklama zezinto ezihlanganisiwe. I-slurry ihlakazeka ngokulinganayo ngokusebenzisa ama-slurries ahlukahlukene futhi yomiswe ngokufuthwa. Phakathi nenqubo yokomisa ngokushesha, ama-nanoparticles nezinye izakhi ku-slurry zizokwakha ngokuzenzakalelayo izici zesakhiwo esinezimbotshana. Leli phepha lisebenzisa ubuchwepheshe bokugaya ibhola obuthuthukisiwe futhi obunobungani bemvelo kanye nobuchwepheshe bokumiswa kwesifutho ukuze kulungiswe izinto ezisekelwe ku-silicon.
Ukusebenza kwezinto ezisekelwe ku-silicon kungabuye kuthuthukiswe ngokulawula i-morphology kanye nezici zokusabalalisa zama-silicon nanomaterials. Njengamanje, izinto ezisekelwe ku-silicon ezine-morphology ehlukahlukene kanye nezici zokusabalalisa sezilungisiwe, njenge-silicon nanorods, i-porous graphite embedded nanosilicon, i-nanosilicon esatshalaliswa kuma-carbon spheres, i-silicon/graphene array array porous structures, njll. Ngesilinganiso esifanayo, uma kuqhathaniswa nama-nanoparticles , ama-nanosheets angakwazi ukucindezela kangcono inkinga yokuchoboza ebangelwa ukukhuliswa kwevolumu, futhi impahla inokuminyana okuphezulu kokuhlanganiswa. Ukupakishwa okungahlelekile kwama-nanosheet nakho kungakha isakhiwo esinezimbotshana. Ukujoyina iqembu le-silicon negative electrode exchange. Nikeza isikhala sebhafa sokunwetshwa kwevolumu yezinto ze-silicon. Ukwethulwa kwe-carbon nanotubes (CNTs) akukwazi nje ukuthuthukisa ukuqhutshwa kwezinto, kodwa futhi kukhuthaze ukwakheka kwezakhiwo ezinama-porous zezinto ngenxa yezimpawu zayo ze-morphological one-dimensional. Ayikho imibiko ngezakhiwo ezinama-porous ezakhiwe ama-silicon nanosheets nama-CNTs. Leli phepha lamukela ukugaya ibhola okusebenzayo ezimbonini, ukugaya kanye nokuhlakazwa, ukomisa isifutho, izindlela ze-carbon pre-coating kanye nezindlela zokubala, futhi lethula abagqugquzeli abanezimbobo ohlelweni lokulungiselela ukulungisa izinto ze-electrode ezimbi ezisekelwe ku-silicon ezakhiwe ngokuzihlanganisa kwama-silicon nanosheets kanye CNTs. Inqubo yokulungiselela ilula, ihambisana nemvelo, futhi akukho ketshezi olulahlwayo noma izinsalela zemfucuza ezikhiqizwayo. Kunemibiko eminingi yezincwadi mayelana ne-carbon coating yezinto ezisekelwe ku-silicon, kodwa kunezingxoxo ezimbalwa ezijulile ngomphumela wokumboza. Leli phepha lisebenzisa i-asphalt njengomthombo wekhabhoni ukuze liphenye imiphumela yezindlela ezimbili zokumboza i-carbon, i-liquid phase coating kanye ne-solid phase coating, emthelela wokugcoba kanye nokusebenza kwe-silicon-based negative electrode materials.
1 Isilingo
1.1 Ukulungiselela impahla
Ukulungiswa kwezinto ezinezimbobo ze-silicon-carbon eyinhlanganisela ikakhulukazi kuhlanganisa izinyathelo ezinhlanu: ukugaya ibhola, ukugaya nokuhlakazeka, ukomisa isifutho, i-carbon pre-coating kanye ne-carbonization. Okokuqala, kala u-500 g we-silicon powder yokuqala (yasekhaya, 99.99% ubumsulwa), engeza u-2000 g we-isopropanol, futhi wenze ukugaya ibhola elimanzi ngesivinini sokugaya ibhola esingu-2000 r/min amahora angu-24 ukuze uthole i-nano-scale silicon slurry. I-silicon slurry etholiwe idluliselwa ethangini lokudlulisa ukuhlakazeka, futhi izinto zokwakha zengezwa ngokwesilinganiso esikhulu se-silicon: i-graphite (ekhiqizwe e-Shanghai, ibanga lebhethri): ama-carbon nanotubes (akhiqizwe e-Tianjin, ibanga lebhethri): i-polyvinyl pyrrolidone (ekhiqiziwe e-Tianjin, ibanga lokuhlaziya) = 40:60:1.5:2. I-Isopropanol isetshenziselwa ukulungisa okuqukethwe okuqinile, futhi okuqukethwe okuqinile kuklanyelwe ukuba kube ngu-15%. Ukugaya nokusabalalisa kwenziwa ngesivinini sokuhlakazeka esingu-3500 r/min ngamahora angu-4. Elinye iqembu lama-slurries ngaphandle kokwengeza ama-CNT liyaqhathaniswa, kanti ezinye izinto ziyafana. Udaka oluhlakaziwe olutholiwe lube seludluliselwa ethangini lokomisa isifutho, futhi ukomiswa kwesifutho kwenziwa endaweni evikelwe nge-nitrogen, lapho izinga lokushisa lokungenisa nokuphuma libe ngu-180 no-90 °C, ngokulandelana. Kwase kuqhathaniswa izinhlobo ezimbili zokumbozwa kwekhabhoni, ukumbozwa kwesigaba esiqinile kanye nokumbozwa kwesigaba se-liquid. Indlela yokugqoka yesigaba esiqinile yile: i-powder eyomisiwe ixutshwe ne-20% asphalt powder (eyenziwe eKorea, i-D50 i-5 μm), ixutshwe ku-mixer engumshini imizuzu eyi-10, futhi isivinini sokuxuba singama-2000 r/min ukuthola. i-powder efakwe ngaphambili. Indlela yokwemboza yesigaba se-liquid ithi: impushana eyomisiwe isifutho yengezwa kwisixazululo sexylene (eyenziwe e-Tianjin, ibanga lokuhlaziya) eliqukethe i-asphalt engu-20% encibilikiswe kumpushana ngokuqukethwe okuqinile okungama-55%, futhi i-vacuum inyakaziswa ngokulinganayo. Bhaka kuhhavini we-vacuum ku-85 ℃ amahora angu-4, ufake ku-mixer engumshini ukuze uxube, isivinini sokuxuba singama-2000 r/min, futhi isikhathi sokuxuba siyimizuzu eyi-10 ukuze uthole impushana efakwe ngaphambili. Ekugcineni, i-powder eboshwe ngaphambili yancishiswa kuhhavini elijikelezayo ngaphansi komkhathi we-nitrogen ngezinga lokushisa elingu-5°C/min. Yaqale yagcinwa ekushiseni okungaguquki okungu-550°C amahora angu-2, bese iqhubeka nokushisa kufika ku-800°C futhi igcinwe ezingeni lokushisa elingashintshi amahora angu-2, bese ipholiswa ngokwemvelo ibe ngaphansi kuka-100°C bese ikhishwa ukuze ithole i-silicon-carbon. impahla eyinhlanganisela.
1.2 Izindlela zokulinganisa izinhlamvu
Ukusatshalaliswa kosayizi wezinhlayiyana kokuqukethwe kwahlaziywa kusetshenziswa isihloli sosayizi wezinhlayiyana (inguqulo ye-Mastersizer 2000, eyenziwe e-UK). Izimpushana ezitholakala esinyathelweni ngasinye zihlolwe ngokuskena i-electron microscopy (Regulus8220, eyenziwe eJapane) ukuze kuhlolwe i-morphology nobukhulu bezimpushana. Isakhiwo sesigaba sezinto ezibonakalayo sahlaziywa kusetshenziswa i-X-ray powder diffraction analyzer (i-D8 ADVANCE, eyenziwe eJalimane), futhi ukwakheka okuyisisekelo kwezinto kwahlaziywa kusetshenziswa i-energy spectrum analyzer. Izinto ezihlanganisiwe ze-silicon-carbon zisetshenziswe ukwenza inkinobho uhhafu weseli yemodeli engu-CR2032, kanye nesilinganiso sesisindo se-silicon-carbon: SP: CNT: CMC: SBR yayingu-92:2:2:1.5:2.5. I-counter electrode iyishidi le-lithium yensimbi, i-electrolyte iyi-electrolyte yokuhweba (imodeli 1901, eyenziwe eKorea), i-Celgard 2320 diaphragm isetshenziswa, uhla lwe-voltage lokushaja nokukhishwa luyi-0.005-1.5 V, ukushaja nokukhipha okwamanje ngu-0.1 C. (1C = 1A), kanti amandla okunqanyulwa kokukhishwa ngu-0.05 C.
Ukuze kuqhutshekwe nophenyo ngokusebenza kwezinto eziyinhlanganisela ye-silicon-carbon, kwenziwa ibhethri elincane le-soft-pack 408595 elamiwe. I-electrode enhle isebenzisa i-NCM811 (eyenziwe e-Hunan, ibanga lebhethri), futhi i-graphite ye-electrode engalungile ifakwe ku-8% we-silicon-carbon material. Ifomula ye-electrode slurry enhle ingu-96% NCM811, 1.2% polyvinylidene fluoride (PVDF), 2% i-ejenti conductive SP, 0.8% CNT, kanye ne-NMP isetshenziswa njenge-dispersant; i-electrode negative slurry formula yi-96% eyinhlanganisela eyinhlanganisela ye-electrode material, 1.3% CMC, 1.5% SBR 1.2% CNT, futhi amanzi asetshenziswa njengesihlakazeka. Ngemva kokunyakazisa, ukugoqa, ukugoqa, ukusika, i-lamination, ukushisela ithebhu, ukupakisha, ukubhaka, umjovo we-liquid, ukwakheka kanye nokuhlukaniswa kwamandla, amabhethri ephakethe amancane angama-408595 ane-laminate enamandla alinganiselwe we-3 Ah. Ukusebenza kwezinga le-0.2C, 0.5C, 1C, 2C ne-3C kanye nokusebenza komjikelezo wokushaja okungu-0.5C nokukhishwa okungu-1C kuhloliwe. Ibanga le-voltage yokushaja nokukhipha lalingu-2.8-4.2 V, ukushaja okungaguquki kwamandla kagesi kanye nokushaja okungaguquki, kanti amandla akhona anqanyuliwe ayengu-0.5C.
2 Imiphumela Nezingxoxo
I-silicon powder yokuqala yabonwa ngokuskena i-electron microscopy (SEM). I-silicon powder yayine-granular ngokungavamile enosayizi wezinhlayiyana ezingaphansi kwe-2μm, njengoba kuboniswe kuMfanekiso 1 (a). Ngemva kokugaya ibhola, usayizi we-silicon powder wehliswa kakhulu waba ngu-100 nm [Umfanekiso 1(b)]. Ukuhlolwa kosayizi wezinhlayiyana kubonise ukuthi i-D50 ye-silicon powder ngemuva kokugaya ibhola yayiyi-110 nm futhi i-D90 yayingu-175 nm. Ukuhlolwa ngokucophelela kwe-morphology ye-silicon powder ngemuva kokugaya ibhola kubonisa isakhiwo esingenalutho (ukwakheka kwesakhiwo esingenalutho kuzoqinisekiswa ngokuqhubekayo kusukela ku-SEM ye-cross-sectional kamuva). Ngakho-ke, idatha ye-D90 etholwe ekuhlolweni kosayizi wezinhlayiyana kufanele ibe ubude bobude be-nanosheet. Kuhlanganiswe nemiphumela ye-SEM, kungahlulelwa ukuthi ubukhulu be-nanosheet etholiwe buncane kunenani elibalulekile le-150 nm yokuphuka kwe-silicon powder ngesikhathi sokushaja nokukhipha okungenani ubukhulu obulodwa. Ukwakheka kwe-flaky morphology ngokuyinhloko kungenxa yamandla ahlukene okuhlukanisa amaplanethi e-crystalline crystalline silicon, phakathi kwawo {111} indiza ye-silicon inamandla aphansi okuhlukanisa {100} kanye {110} nezindiza zekristalu. Ngakho-ke, le ndiza yekristalu incitshwa kalula ngokugaywa kwebhola, futhi ekugcineni yakha isakhiwo esithambile. Isakhiwo esithambile sivumela ukunqwabelana kwezakhiwo ezixekethile, sigcine isikhala sokunwetshwa kwevolumu ye-silicon, futhi sithuthukisa ukuqina kwento.
I-slurry equkethe i-nano-silicon, i-CNT ne-graphite yafuthwa, futhi impushana ngaphambi nangemva kokufutha yahlolwa yi-SEM. Imiphumela ikhonjiswe ku-Figure 2. I-matrix ye-graphite eyengezwe ngaphambi kokufafaza isakhiwo se-flake esivamile esinosayizi we-5 kuya ku-20 μm [Umdwebo 2 (a)]. Isivivinyo sokusabalalisa usayizi wezinhlayiyana zegraphite sibonisa ukuthi i-D50 ingu-15μm. Impushana etholwe ngemva kokufafaza ine-morphology eyindilinga [Figure 2(b)], futhi kungabonakala ukuthi i-graphite imbozwe ungqimba lokumboza ngemva kokufafaza. I-D50 yempushana ngemva kokufafaza ingu-26.2 μm. Izici ze-morphological zezinhlayiya zesibili zabonwa yi-SEM, ebonisa izici zesakhiwo esinezimbotshana ezivulekile eziqoqwe ama-nanomaterials [Umfanekiso 2(c)]. Isakhiwo esinezimbotshana sakhiwe ngama-silicon nanosheet kanye nama-CNT ahlanganiswe namanye [Umfanekiso 2(d)], futhi indawo eqondile yokuhlola (BET) iphezulu njengo-53.3 m2/g. Ngakho-ke, ngemva kokufafaza, ama-silicon nanosheets kanye nama-CNT ayazihlanganisa ukuze akhe isakhiwo esinezimbotshana.
Isendlalelo se-porous saphathwa nge-liquid carbon coating, futhi ngemva kokwengeza i-carbon coating precursor pitch kanye ne-carbonization, ukubhekwa kwe-SEM kwenziwa. Imiphumela iboniswa ku-Figure 3. Ngemuva kokugcoba i-carbon pre-coating, ubuso bezinhlayiya zesibili buba bushelelezi, bube nesendlalelo esicacile sokugqoka, futhi ukugqoka kuqedile, njengoba kuboniswe ku-Figure 3 (a) no (b). Ngemuva kwe-carbonization, ungqimba olungaphezulu lokugqoka lugcina isimo esihle sokugqoka [Umfanekiso 3(c)]. Ukwengeza, isithombe se-SEM esiphambanweni sibonisa ama-nanoparticles amise okwe-strip [Umfanekiso 3(d)], ohambisana nezici ze-morphological zama-nanosheets, ngokuqhubekayo eqinisekisa ukwakheka kwama-silicon nanosheets ngemva kokugaya ibhola. Ngaphezu kwalokho, Umfanekiso 3(d) ubonisa ukuthi kukhona okugcwalisa phakathi kwama-nanosheet athile. Lokhu kubangelwa ikakhulukazi ukusetshenziswa indlela liquid isigaba enamathela. Isixazululo se-asphalt sizongena ezintweni, ukuze ubuso be-silicon nanosheets bangaphakathi buthole isendlalelo sokuzivikela se-carbon coating. Ngakho-ke, ngokusebenzisa i-liquid phase coating, ngaphezu kokuthola umphumela we-particle yesibili yokugqoka, umphumela we-carbon double coating we-primary particle coating ungabuye utholakale. Impushana eyenziwe ngekhabhoni yahlolwa yiBET, futhi umphumela wokuhlolwa wawungu-22.3 m2/g.
I-carbonized powder yafakwa ekuhlaziyweni kwe-spectrum yamandla e-cross-sectional (EDS), futhi imiphumela iboniswa kuMfanekiso 4 (a). I-micron-size core iyincenye engu-C, ehambisana ne-graphite matrix, futhi uqweqwe lwangaphandle luqukethe i-silicon nomoya-mpilo. Ukuze kuqhutshekwe kuphenywe ukwakheka kwe-silicon, kwenziwa ukuhlolwa kwe-X-ray diffraction (XRD), futhi imiphumela iboniswa kuMfanekiso 4(b). Izinto ezisetshenziswayo ikakhulukazi zakhiwe nge-silicon ye-graphite ne-single-crystal, engenazo izici ezicacile ze-silicon oxide, okubonisa ukuthi ingxenye ye-oksijini yokuhlolwa kwe-spectrum yamandla ngokuyinhloko ivela ku-oxidation yemvelo yendawo ye-silicon. I-silicon-carbon composite material ibhalwe njenge-S1.
I-silicon-carbon material S1 elungisiwe yafakwa ngaphansi kokukhiqizwa kwe-half cell cell kanye nokuhlolwa kokushaja. Ijika lokuqala lokushaja liboniswa kuMfanekiso 5. Umthamo othize obuyisele emuva u-1000.8 mAh/g, futhi ukusebenza kahle komjikelezo wokuqala kuphezulu njengo-93.9%, okungaphezulu kokusebenza kahle kokuqala kwezinto eziningi ezisekelwe ku-silicon ngaphandle kwe-pre- lithiation kubikwe ezincwadini. Ukusebenza kahle kokuqala okuphezulu kukhombisa ukuthi izinto ezihlanganisiwe ze-silicon-carbon zinokuzinza okuphezulu. Ukuze uqinisekise imiphumela yesakhiwo se-porous, inethiwekhi ye-conductive kanye ne-carbon coating ekuzinzeni kwezinto ze-silicon-carbon, izinhlobo ezimbili zezinto ze-silicon-carbon zalungiswa ngaphandle kokungeza i-CNT futhi ngaphandle kwe-carbon coating eyinhloko.
I-morphology ye-carbonized powder ye-silicon-carbon composite material ngaphandle kokwengeza i-CNT iboniswa ku-Figure 6. Ngemuva kokufakwa kwesigaba se-liquid kanye ne-carbonization, isendlalelo sokugqoka singabonakala ngokucacile ebusweni bezinhlayiya zesibili ku-Figure 6 (a). I-SEM ye-cross-sectional ye-carbonized material ikhonjiswe kuMfanekiso 6(b). Ukupakishwa kwama-silicon nanosheets kunezici ezimbotshana, kanti ukuhlolwa kweBET kungu-16.6 m2/g. Kodwa-ke, uma kuqhathaniswa necala ne-CNT [njengoba kuboniswe ku-Figure 3 (d), ukuhlolwa kwe-BET kwe-powder yayo ye-carbonized yi-22.3 m2 / g], ukuminyana kwangaphakathi kwe-nano-silicon stacking kuphezulu, okubonisa ukuthi ukungezwa kwe-CNT kungakhuthaza. ukwakheka kwesakhiwo esinezimbotshana. Ngaphezu kwalokho, i-material ayinayo inethiwekhi ye-conductive ye-three-dimensional eyakhiwe yi-CNT. I-silicon-carbon composite material ibhalwe njenge-S2.
Izici ze-morphological ze-silicon-carbon composite material ezilungiselelwe yi-solid-phase carbon coating ziboniswa ku-Figure 7. Ngemuva kwe-carbonization, kukhona ungqimba olubonakalayo olubonakalayo ebusweni, njengoba kuboniswe ku-Figure 7 (a). Umfanekiso 7(b) ubonisa ukuthi kukhona ama-nanoparticles amise okwe-strip esigabeni esiphambanayo, ahambisana nezici ze-morphological zama-nanosheet. Ukuqoqwa kwama-nanosheet kwakha isakhiwo esinezimbotshana. Asikho isigcwalisi esisobala ebusweni bama-nanosheet angaphakathi, okubonisa ukuthi i-solid-phase carbon coating yakha kuphela ungqimba lwe-carbon coating olunesakhiwo esinezimbotshana, futhi asikho isendlalelo sangaphakathi sokumboza sama-silicon nanosheets. Le nto eyinhlanganisela ye-silicon-carbon ibhalwe njenge-S3.
Ukuhlolwa kohlobo lwenkinobho ye-half cell charge kanye nokukhishwa kwenziwa ku-S2 naku-S3. Umthamo othize kanye nokusebenza kahle kokuqala kwe-S2 bekuyi-1120.2 mAh/g no-84.8%, ngokulandelana, futhi umthamo othize nokusebenza kahle kokuqala kwe-S3 bekungama-882.5 mAh/g no-82.9%, ngokulandelana. Umthamo othize kanye nokusebenza kahle kokuqala kwesampula ye-S3 ehlanganiswe nesigaba esiqinile bekungaphansi kakhulu, okubonisa ukuthi kuphela ukumbozwa kwekhabhoni yesakhiwo esinezimbotshana ezenziwe, futhi ukumbozwa kwekhabhoni kwama-silicon nanosheets angaphakathi akuzange kwenziwe, okungakwazi ukunikeza umdlalo ogcwele. kumthamo othize wezinto ezisekelwe ku-silicon futhi ayikwazanga ukuvikela ubuso bezinto ezisekelwe ku-silicon. Ukusebenza kahle kokuqala kwesampula ye-S2 ngaphandle kwe-CNT nakho kwakuphansi kunaleyo yezinto ezihlanganisiwe ze-silicon-carbon equkethe i-CNT, okubonisa ukuthi ngesisekelo sesendlalelo esihle sokumboza, inethiwekhi ye-conductive kanye nezinga eliphakeme lesakhiwo se-porous kulungele ukuthuthukisa. wokushaja nokusebenza kahle kokukhipha i-silicon-carbon material.
Okubalulekile kwe-silicon-carbon ye-S1 kwasetshenziswa ukwenza ibhethri elincane elinephakethe elithambile eligcwele ukuhlola ukusebenza kwezinga nokusebenza komjikelezo. Ijika lezinga lokukhishwa liboniswa kuMfanekiso 8(a). Amandla okukhipha we-0.2C, 0.5C, 1C, 2C kanye ne-3C yi-2.970, 2.999, 2.920, 2.176 kanye ne-1.021 Ah, ngokulandelanayo. Izinga lokukhishwa kwe-1C liphezulu njenge-98.3%, kodwa izinga lokukhishwa kwe-2C lehla laya ku-73.3%, futhi izinga lokukhishwa kwe-3C lehla liye ku-34.4%. Ukuze ujoyine iqembu le-silicon negative electrode exchange, sicela ungeze i-WeChat: shimobang. Ngokwezinga lokushaja, amandla okushaja angu-0.2C, 0.5C, 1C, 2C kanye ne-3C angu-3.186, 3.182, 3.081, 2.686 kanye no-2.289 Ah, ngokulandelana. Izinga lokushaja le-1C lingama-96.7%, kanti izinga lokushaja le-2C lisafinyelela ku-84.3%. Kodwa-ke, uma ubheka ijika lokushaja kuMfanekiso 8(b), iplathifomu yokushaja engu-2C inkulu kakhulu kuneplathifomu yokushaja engu-1C, futhi umthamo wayo wokushaja wamandla kagesi ubiza kakhulu (55%), okubonisa ukuthi ukuhlukaniswa kwebhethri elingashajwa elingu-2C vele inkulu kakhulu. Impahla ye-silicon-carbon inokusebenza okuhle kokushaja nokukhipha ku-1C, kodwa izici zesakhiwo zezinto ezibonakalayo zidinga ukuthuthukiswa ngokwengeziwe ukuze kuzuzwe ukusebenza kwezinga eliphezulu. Njengoba kuboniswe kuMfanekiso 9, ngemva kwemijikelezo engu-450, izinga lokugcinwa kwamandla lingama-78%, okubonisa ukusebenza kahle komjikelezo.
Isimo esingaphezulu se-electrode ngaphambi nangemva komjikelezo waphenywa yi-SEM, futhi imiphumela iboniswa kuMfanekiso 10. Ngaphambi komjikelezo, ingaphezulu le-graphite ne-silicon-carbon materials icacile [Umfanekiso 10 (a)]; ngemva komjikelezo, ungqimba olunamathelayo ngokusobala lukhiqizwa phezulu [Umfanekiso 10(b)], okuyifilimu ewugqinsi ye-SEI. Ubunzima befilimu ye-SEIUkusetshenziswa kwe-lithium esebenzayo kuphezulu, okungakukhuthazi ukusebenza komjikelezo. Ngakho-ke, ukukhuthaza ukwakheka kwefilimu ye-SEI ebushelelezi (njengokwakhiwa kwefilimu ye-SEI yokwenziwa, ukwengeza izithasiselo ezifanele ze-electrolyte, njll.) kungathuthukisa ukusebenza komjikelezo. Ukubuka kwe-SEM okuphambanayo kwezinhlayiya ze-silicon-carbon ngemva komjikelezo [Umdwebo 10(c)] kubonisa ukuthi ama-silicon nanoparticles asekuqaleni amise okwe-strip ase amaholoholo futhi isakhiwo se-porous sesisusiwe ngokuyisisekelo. Lokhu ikakhulukazi ngenxa yokwanda kwevolumu okuqhubekayo kanye nokufinyezwa kwezinto ze-silicon-carbon phakathi nomjikelezo. Ngakho-ke, isakhiwo esinezimbotshana sidinga ukuthuthukiswa ngokwengeziwe ukuze sinikeze isikhala esanele sebhafa sokunwetshwa kwevolumu yezinto ezisekelwe ku-silicon.
3 Isiphetho
Ngokusekelwe ekwandiseni ivolumu, ukungahambi kahle kahle kanye nokungaqini kahle kwesixhumi esibonakalayo sezinto zokwenziwa kwe-silicon-based negative electrode, leli phepha lenza ukuthuthukiswa okuhlosiwe, kusukela ekubunjweni kwe-morphology yama-silicon nanosheets, ukwakhiwa kwesakhiwo se-porous, ukwakhiwa kwenethiwekhi ye-conductive kanye ne-carbon coating ephelele yazo zonke izinhlayiya zesibili. , ukuthuthukisa ukuzinza kwe-silicon-based negative electrode materials iyonke. Ukuqoqwa kwama-silicon nanosheets kungakha isakhiwo esinezimbotshana. Ukwethulwa kwe-CNT kuzothuthukisa ukwakheka kwesakhiwo se-porous. I-silicon-carbon composite material elungiswe yi-liquid phase coating inomphumela ophindwe kabili we-carbon coating kunaleyo elungiselelwe ukunamathela kwesigaba esiqinile, futhi ibonisa umthamo othize ophezulu kanye nokusebenza kahle kokuqala. Ngaphezu kwalokho, ukusebenza kahle kokuqala kwezinto ezihlanganisiwe ze-silicon-carbon equkethe i-CNT kuphakeme kunalokho ngaphandle kwe-CNT, okubangelwa ikakhulukazi izinga eliphakeme lekhono lesakhiwo esinezimbotshana zokunciphisa ukunwetshwa kwevolumu yezinto ezisekelwe ku-silicon. Ukwethulwa kwe-CNT kuzokwakha inethiwekhi ye-conductive ye-three-dimensional, kuthuthukise ukuqhutshwa kwezinto ezisekelwe ku-silicon, futhi kubonise ukusebenza okuhle kwezinga ku-1C; futhi impahla ikhombisa ukusebenza kahle komjikelezo. Kodwa-ke, isakhiwo esinama-porous sezinto ezibonakalayo sidinga ukuqiniswa ngokwengeziwe ukuze kunikeze isikhala esanele se-buffer sokunwetshwa kwevolumu ye-silicon, futhi kukhuthaze ukwakheka kokubushelelezi.kanye nefilimu eminyene ye-SEI ukuze kuthuthukiswe ukusebenza komjikelezo wezinto eziyinhlanganisela ye-silicon-carbon.
Siphinde sihlinzeke ngemikhiqizo ye-high-purity graphite kanye ne-silicon carbide, esetshenziswa kabanzi ekucubunguleni i-wafer efana ne-oxidation, i-diffusion, kanye ne-annealing.
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Isikhathi sokuthumela: Nov-13-2024