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 In Hyuk Son Jong Hwan Park Soonchul Kwon Seongyong Park Mark H. Rümmeli Alicja Bachmatiuk Hyun Jae Song Junhwan Ku Jang Wook Choi Jae-man Choi Seok-Gwang Doo Hyuk Chang Abstrak Sililikoni elandolwe ngokuqiniseka njengempahla esebenzayo yama-anode ebhethri elandelayo ye-lithium-ion ngenxa ye-capacity yayo engalingani. Noma kunjalo, ivolumu enkulu yesilicon ngaphezu kwemijikelezo ye-charge–discharge yehlisa ukuncintisana kwayo ku-volumetric energy density nasekuphileni komjikelezo. Lapha sibika ukukhula okuqondile kwe-graphene phezu kwama-nanoparticle wesilicon ngaphandle kokwakheka kwe-silicon carbide. Izendlalelo ze-graphene eziboshwe phezu kobuso besilicon zivumela ukwanda kwevolumu yesilicon ngokusebenzisa inqubo yokushelela phakathi kwezendlalelo ze-graphene eziseduze. Lapho ihlanganiswa ne-cathode ye-lithium cobalt oxide evamile, isigqoko se-graphene esingenayo i-silicon carbide sivumela iseli eligcwele ukuba lifinyelele ku-volumetric energy densities engu-972 kanye no-700 Wh l−1 ku-cycle yokuqala kanye ne-200, ngokulandelana, 1.8 kanye no-1.5 izikhathi eziphakeme kunezo zamabhethri ajwayelekile e-lithium-ion. Le ngqondo ibonisa ukuthi ubujamo obungamasendlalelo amabili e-graphene kanye nokuhlanganiswa kwayo okungenayo i-silicon carbide nesilicon kungasebenza njengesibonelo ekuphumeleliseni ama-anode esilicon kube ubuchwepheshe obusebenziseka kalula. Isingeniso I-theoretical gravimetric capacity yesilicon (Si) ifinyelela cishe ku-4,000 mAh g−1. Le nombolo engalingani isikhuthaze umphakathi webhethri ukuthi ubeke imizamo emikhulu yocwaningo ngoba i-high gravimetric capacity ivumela ukuthi kwandiswe kakhulu amandla amandla ama-lithium-ion batteries (LIBs), futhi ngaleyo ndlela kulethwe izicelo ze-LIB ezizayo, njengezimoto zikagesi, zibe yiqiniso , , , , . Edekade elidlulile, izakhiwo ezahlukahlukene ze-electrode ezithuthukisiwe , , , , , , , , , ,  kanye nemiklamo yezibopho , ,  kwakhiwa ukuxazulula izinkinga zokungasebenzi kahle kwe-capacity okuvela ekwandeni kwevolumu okukhulu kwe-Si, okuholela ekusebenzeni okuthuthukisiwe komjikelezo ngisho nangaphezu kwezinkulungwane zemijikelezo . Naphezu kwe-gravimetric value ethembisayo kanye nentuthuko ebalulekile ekuphileni komjikelezo, ama-anode amaningi e-Si abonisiwe kuze kube manje agxile kakhulu ku-gravimetric capacity kodwa awanikezanga isithembiso esifanayo ku-volumetric capacity yawo ngoba imiklamo ekhona ye-electrode ithembele kusikhala esichaziwe kusengaphambili ukuze silungiselele ukwanda kwevolumu kwe-Si. Kuzicelo eziningi ze-LIB okubandakanya izinto zikagesimolayo, noma kunjalo, i-volumetric energy density kuyisici esibalulekile ekunqumeni ukusebenza kwebhethri. Kanye ne-cycle life ephansi, i-weak volumetric energy density njengamanje iyinqaba enkulu ekufakweni kwama-anode e-Si kumazeli okuthengiswayo. Ukuhlangabezana nale mfuneko ebalulekile, ubuchwepheshe be-Si anode budinga ukubuyekezwa ngemiklamo ehlukene ye-electrode enikeza ukusebenza okuqinile komjikelezo ngenkathi ivolumu ye-electrode incishiswe. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 11 Yize kukhona izimo eziningi ze-Si kanye nezingxube zazo nezinye izinto eziqhuba ugesi ezitholakala njengamanje, ukuze kutholakale isixazululo esiphuthumayo sokwenziwa okwangempela okudinga ukulawulwa kwekhwalithi ephezulu, ukuhlanganiswa okulula nokukalelwayo kwezingxenye ezisebenzayo ze-Si kubalulekile. Ngokombono wesicelo esisebenzayo, phakathi kwezinketho eziningi ezingenzeka, ukusetshenziswa kwe-commercial Si nanoparticles (NPs) ngokugqoko okungalula nokusebenzayo kokuhlanza ubuso kungaba kuhle kakhulu. Izinto eziningi eziqhuba ugesi okubandakanya i-amorphous carbon (AC) ziye zahlanganyelwa njengezinto zokugqoko zama-anode e-Si NP , , . Noma kunjalo, eziningi zazo azikwazi ukunikeza ukusebenza okuzinzile kwesikhathi eside ngoba izinto zokugqoko ezisetshenzisiwe azikwazi ukubhekana nokwanda kwevolumu kwe-Si futhi ngenxa yalokho ziyaqhekeka ngaphezu kwemijikelezo ephindaphindayo. 8 20 21 Ngomzamo wokuxazulula umkhawulo wama-coatings okuqhuba ugesi wangaphambili kanye nokuzuza ukusebenza okuhle komjikelezo nge-volumetric energy density ephakeme kakhulu, kulolu cwaningo, samukela i-graphene ye-multilayer ekhule ngqo phezu kobuso be-Si njengento yokugqoko. Isici esingamasendlalelo amabili (2D) se-graphene sinikeza ukusebenza okuyingqayizivele nokusebenzayo kwama-anode e-Si ngoba i-graphene ye-multilayer ingabhekana nokwanda kwevolumu ye-Si ngokusebenzisa inqubo yokushelela phakathi kwezendlalelo eziseduze ngaphandle kwesidingo sokunikeza isikhala kuqala ku-electrode eyenziwe. Futhi, i-pellet ye-Si NP egqoke i-graphene ibonise i-12.8 S cm−1 ku-graphene content engu-1 wt% ngokusebenzisa inethiwekhi ephezulu ye-percolation. Ngalesi sizathu, sinqoba inkinga yokukhula kwe-graphene ngqo phezu kobuso be-Si ngaphandle kokwakheka kwe-silicon carbide (SiC) ngokuthuthukisa inqubo ye-chemical vapour deposition (CVD) ebandakanya i-oxidant yomlomo. Ukwakheka kwe-SiC kuyabulala ekusebenzeni kwe-Si anode ngoba i-SiC iyinto engaqhuba ugesi enezici ezimbalwa ezimbi. Ngaphezu kwalokho, i-SiC ayisebenzi ekuphenduleni ngama-ion e-Li futhi ngenxa yalokho ivimbela ukungena kwe-Li ion endaweni ye-Si. Ngosizo lwenqubo yokushelela ye-graphene interlayer kanye nokuthuthukiswa kokuqhuba ugesi, ama-Si NP agqoke i-graphene afikela ku-2,500 mAh cm−3 (vs 550 mAh cm−3 ye-graphite evamile), inani eliphakeme kakhulu phakathi kwalokho okubikwe kuze kube manje kunoma yimaphi ama-anode e-LIB ngenkathi abonisa ukusebenza okuhle komjikelezo kanye nezinga. Imiphumela Ukukhula kwe-graphene okungenayo i-SiC phezu kwe-Si Ukusetshenziswa okuqondile kwe-graphene esezingeni eliphakeme phezu kwe-Si nge-CVD kuye kwaba yinselele  ngoba izimo ezijwayelekile zokuhlanganiswa kwe-graphene zidinga imvelo yokunciphisa evame ukukhipha ungqimba lwendalo lwe-Si oxide ebusweni be-Si, bese lucindezela ukusabela phakathi kwe-Si kanye neziqalo zekhabhoni ezihlakazekile ukwakha i-SiC . Indlela yethu yokuqala yokusebenzisa i-methane (CH4) njengesiqu somoya wekhabhoni esihlanganiswe ne-H2 yayingakwazi ukuthola ukukhula kwe-graphene ku-Si NPs ( ), ngaleyo ndlela ikhiqiza kuphela i-β-SiC ( ). Ukunqoba le mikhawulo, sifake i-carbon dioxide (CO2), i-oxidant yomlomo, ku-CVD process kanye ne-CH4 (refs  ,  ). Ukufakwa kwe-CO2 kuvumela ukugwema ukwakheka kwe-SiC futhi kunciphise izinga lokushisa lokukhula uma kuqhathaniswa nokukhula kwe-graphene okwaziwayo ebusweni . Esivivinyweni sethu, ku-900 °C, ukukhula kwe-graphene kwakungaphelele noma kungahambisani ( ), ngenkathi ukukhula kwe-graphene ku-1,100 °C kukhiqize izingqimba ze-oxide phezu kobuso be-Si ezazinobukhulu kakhulu ukuze kube nokungena kwe-Li ion ( ). Ku-1,000 °C, amazinga angu-2–10 e-graphene akheke njengoba kukhonjiswa ezithombeni ze-transmission electron microscope (TEM) ( ) abonisa ngokucacile ubujamo obungamasendlalelo kanye nebanga phakathi kwezendlalelo eliseduze kwe-3.4 Å ( , inset). Ukuhlola okuseduze kubonisa ukuthi izendlalelo ngazinye ziboshwe ngqo phezu kobuso besikhonkwane se-Si ezindaweni zazo (imicibisholo ebomvu ku- ) futhi zihambisana nobuso be-Si. Lezi zendlalelo ze-graphene ezihlelwe kahle zingagcina ubujamo bazo obungamasendlalelo ngisho nangaleso sikhathi sokubuyisa i-lithium ngokusebenzisa inqubo yokushelela ( ), ngaleyo ndlela zinikeza indlela ehlakaniphile yokubhekana nokwanda kwevolumu kwe-Si. Ukukhula kwe-graphene kuye kwazanywa phezu kobuso be-Si dioxide (SiO2) kusetshenziswa i-CH4 ne-H2 (refs  , ). Noma kunjalo, ukukhula kwe-graphene kulezi zinqubo kwakungephumeleli kakhulu noma akuzange kugweme ukwakheka kwe-SiC. Ukukhula okungaphumeleli kubangelwa izindawo zokubambelela ezinganele phezu kobuso be-SiO2. Ngokuphambene, engozini yethu, ukufakwa kwe-CO2 kwakha izindawo eziningi zokubambelela ngesimo se-SiOx ezinye izinkinga. 22 23 Supplementary Fig. 1 Supplementary Fig. 2 24 25 23 Supplementary Fig. 3 Supplementary Fig. 4 Fig. 1a,b Fig. 1b Fig. 1c Fig. 1d 26 27   ( ) Isithombe se-TEM esiphansi sokusondeza se-Gr–Si NP. ( ) Isithombe se-TEM esiphakeme sokusondeza se-Gr–Si NP efanayo esivela ebhokisini elimhlophe ku- . (Izithombe zangaphakathi) Amaprofayela omugqa avela ebhokisini elibomvu abonisa ukuthi ibanga phakathi kwezendlalelo ze-graphene lingama-∼3.4 Å, livumelana kahle nalawa ezendlalelo ze-graphene ezijwayelekile ezisuselwe ku-van der Waals interaction. ( ) Isithombe se-TEM esiphakeme sokusondeza esibonisa imvelaphi (imicibisholo ebomvu) lapho izendlalelo ze-graphene ngazinye zikhula khona. ( ) Isithombe esichazayo esikhombisa inqubo yokushelela yezendlalelo zokugqoka i-graphene ezikwazi ukubamba ukwanda kwevolumu ye-Si. a b a c d Ukukhula kwe-graphene okungenayo i-SiC kwavunyelwa ngokuhlaziywa okusuka esikalini esikhulu kanye nesingabantu abangabodwana. Amaprofayela e-X-ray photoelectron spectroscopy ebhandeni le-Si 2p ( ) kanye nezi-spectra ze-X-ray diffraction (XRD) ( ) ayibonisi iziqongo ezihambelana ne-SiC ye-graphene-coated Si (Gr–Si), i-AC-coated Si (AC–Si) kanye ne-Si eyimpuphu, ngokuphambene nesampula elawulayo (SiC–Si) elenziwe ngendlela engena-CO2 kusetshenziswa i-CH4 ne-H2. Ngakolunye uhlangothi, ukudweba kwe-TEM kusetshenziswa i-high-angle annular dark field kwabonisa ukuthi i-Si NP inobujamo be-core–shell obunokuqhakaza okuqhakazayo kanye ne-shell emnyama ngokulinganayo ebekelwe i-Si core kanye nokugqoko kwe-oxide ( ). Ama-spectra e-Electron energy loss spectroscopy (EELS) ( ) atholwe ezindaweni eziningi kulo lonke i-NP akubonisa noma yiziphi izimpawu  ebonisa ukwakheka kwe-SiC, kuqinisekisa ukukhula okungenayo i-SiC kwinqubo yokukhula kwamanje. Futhi, izimpawu ze-SiO2 ku-108 eV zazitholakala ezindaweni 1 kanye ne-2 ngamandla kunezinye izindawo phakathi, okubonisa ukuthi ubuso be-SiO2 bungasebenza njengezindawo zokubambelela ekukhuleni kwe-graphene. Ukuba khona okuphikelelayo kwezingqimba zokuqala ze-SiO2 kwavunyelwa futhi ngokuhlaziywa kwe-XRD ( ) kanye ne-EELS ( ). Fig. 2a Supplementary Fig. 2 Fig. 2b Fig. 2c 28 Supplementary Fig. 2 Fig. 2b,c   ( ) Ama-spectra e-X-ray photoelectron spectroscopy ebhandeni le-Si 2p le-Gr–Si, SiC–Si, AC–Si kanye ne-Si eyimpuphu. ( ) Isithombe se-scanning TEM se-Gr–Si NP. ( ) Ama-spectra e-EELS ezindaweni ezikhonjwe ku- . a b c b Ukuhlaziywa kwe-TEM okutholakala ku- in situ Manje sibheka ukusetshenziswa kwe-Gr–Si njengempahla ye-anode kumabhayisikili e-LIB. I-lithiation yama-Gr–Si NPs (1 wt% graphene) yalandelwa ngesikhathi sangempela ngesikhathi sokwanda kwevolumu yayo kusetshenziswa ukuhlaziywa kwe-TEM okutholakala ku- , , , . Esivivinyweni sangempela, amanye ama-Gr–Si nanoparticles abekwe ku-electrode eqiniswe ngegoli (Au). I-electrode yesibili, kodwa eyenziwe ukuhambisa, eno-Li/LiO2 ekupheleni kwayo yayibekwe ukuze ithinte ama-Gr–Si NPs ukuze ayiguqulele ku-lithium ( ). Uma nje ukuthintana ne-electrode yesibili kwenziwa, ama-nanoparticles aqala ukubola ( ). Imininingwane eyengeziwe ngale nqubo ingabonwa ku-  kanye nama-movie apholile we-Supplementary  . Izinhlobo ezimbili zezakhiwo ezibolekayo zabonwa, okungukuthi, ama-nanoparticles angenawo amaphutha kanye nama-nanoparticles anamaphutha njengoba kugqanyiswe ku- . Ezimweni lapho i-graphene igcwalisa ngokuphelele i-nanoparticle futhi ayinazo izindawo ezicacile zamaphutha ( ), ububanzi kwakwanda ngo-∼30% (220% i-volume expansion). Ekupheleni kwe-lithiation, ibanga phakathi kwezendlalelo zezendlalelo ze-graphene likhuphuke laba ngu-3.8 Å libonisa ukufakwa kwe-Li , futhi isici sobujamo be-graphitic coating sagcinwa nxazonke ze-NP ( ), okubonisa inqubo yokushelela phakathi kwezendlalelo njengoba kuchaziwe ku- . Ezimweni lapho kukhona indawo enesici (bona isiyingi esiluhlaza ku- ), lapho ibola, i-nanoparticle yangaphakathi iyachithwa futhi iqhekeke ngendlela enesici ( ). Ukuziphatha okuhlukene kokuqhekeka okubonwayo akunakwenzeka ukuthi kuvele kusuka osayizi we-nanoparticle, njengoba i-nanoparticle egcwele eyayinkudlwana kune-fractured eyayiku-  yephukanga (bona ama-nanoparticles akhonjwe ku-0 kanye no-40 s ku- ). Futhi, ukubona kwakamuva  kubonisa ukuthi uma ingagcwalisiwe, ngisho nama-nanoparticles amancane e-Si (<50 nm) angaphuka ngenxa ye-Li concentration gradient ngaphakathi kwama-nanoparticles anganeka ingcindezi enkulu. Eqinisweni, usayizi obalulekile wokuphuka kwe-nanoparticle ye-Si ungadlulela ku->200 nm (ref.  ). in situ 29 30 31 32 Fig. 3a Fig. 3b Supplementary Fig. 5 1–3 Fig. 3b,c Fig. 3d 33 Fig. 3d Fig. 3c Fig. 3a Fig. 3e Fig. 3 Supplementary Fig. 5 34 35 ">   in situ ( ) Ama-Gr–Si NP anamathele ebusweni be-Au wire kanye ne-electrode yesibili ye-Li/LiO2. ( ) Ama-Gr–Si NP afanayo ngemuva kwe-lithiation. ( ) Isifinyezo esihleliwe sama-Gr–Si NP alithiyathayo womabili angenawo amaphutha kanye anama-phutha egqoke i-graphene. ( , ) Izithombe ze-TEM ezisondeziwe kakhulu ze- ( ) nanoparticle engenawo amaphutha (leyo eboshwe ngomugqa obomvu ku-  kanye no- ) kanye ( ) nanoparticle enesici (leyo eboshwe ngomugqa oluhlaza okwesibhakabhaka ku-  kanye no- ). Ama-EELS spectra kuzo zombili izimo aqinisekisa i-lithiation. Amaprofayela omugqa avela kumabhokisi abomvu kuzo zombili izimo abonisa ukwanda kwezingqimba ze-interlayer cishe ngo-3.8 Å, kubonisa i-lithiation esikhundleni se-graphene interlayer space. a b c d e d a b e a b Ukuhlaziywa kwe-EELS kwendawo ngesikhathi se-lithiation kuqinisekisa i-lithiation ye-Si kuzo zombili izimo ngokusebenzisa i-Li K-edge engacacile eduze kwe-55 eV kanye ne-Si L-edge ku-100 eV ( ; ref.  ). Isendlalelo esiboniswe ebusweni be-graphene ku-  sihambisana nokuthunyelwa kwe-Li/Li2O. Ngokuyisisekelo, izendlalelo ze-graphene zigcina ukuhlanganiswa ne-Si ngokusebenzisa izimpande zazo eziboshwe ngokokhemikhali ebusweni be-Si, futhi ngesikhathi esifanayo, inqubo yokushelela ivumela isigqoko se-graphene esinezendlalelo ezimbalwa ukuba sibheke ukwanda kwevolumu kwe-Si. Kwenye isivivinyo se-TEM se-  ene-Gr–Si LIB electrode, kwabonwa ukuthi isilinganiso senani lezendlalelo ze-graphene ezilinganiswe ezindaweni ezahlukene sehle sisuka ku-9.4 saya ku-5.6 izendlalelo ( ) ngemuva kwe-lithiation yokuqala, iqinisekisa futhi inqubo yokushelela phakathi kwezendlalelo. Fig. 3d,e 36 Fig. 3d ex situ Supplementary Fig. 6 Ukugcwaliswa kwe-graphene kanye nenqubo yokushelela phakathi kwezendlalelo kubangela amandla okubamba asiza ukugcina ubuqotho besikhonkwane se-Si ngesikhathi sokwanda kwevolumu. Noma kunjalo, le ndlela yokubamba ayibonakali ithinta ukungena kwe-Li, njengoba kutholakala amakhono aqinile ezilinganisweni zikagesimolayo. Kubuye kuphawuleke ukuthi ukwanda kwevolumu kwama-nanoparticles, ngaphezu kwakho konke, kwakuhambisana ngazo zonke izinkomba ezifana nezinga noma ngabe indawo yokuxhumana ne-electrode yesibili yalinganiselwe. Lokhu kugqamisa ukuth

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