Iyini Iseli Yebhethri?
Isakhiwo Seseli
Ibhethri elilodwa, elaziwa nangokuthi "iseli", iyunithi encane yesistimu yebhethri. Ngokuyinhloko yakhiwa i-cathode (i-Cathode Electrode), i-anode (i-Anode Electrode), i-electrolyte (i-Electrolyte), isihlukanisi (Isihlukanisi), kanye necala (Ikesi), njengoba kuboniswe ku-Figure 7-1.
Ishidi le-electrode leseli ye-ion ye-lithium- lingahlukaniswa njengento eyinhlanganisela, ikakhulukazi ehlanganisa izingxenye ezine:
1)Izinhlayiya zezinto ezisebenzayo ezihlanganisa noma ezihlukanisa i-lithium ion; izinhlayiya ze-cathode zinikeza umthombo we-lithium, kuyilapho izinhlayiya ze-anode zamukela i-lithium ion.
2)Isigaba se-conductive (isigaba sejeli ye-carbon) esakhiwe ingxube ye-ejenti eqhubayo kanye nomqoqi wamanje, ne-binder esebenza umsebenzi wokuhlanganisa; i-coating iqhuba ama-electron ngokusebenzisa umqoqi wamanje kanye ne-agent conductive.
3)Izimbotshana ezigcwele i-electrolyte, esebenza njengeziteshi zokuthutha i-lithium-ze-ion ngaphakathi kweshidi le-electrode.
4) Umqoqi wamanje.
Ngesikhathi senqubo ye-electrochemical, ukunamathela kwe-electrode kuhilela ikakhulukazi izinqubo ezi-4 ezilandelayo:
1)Ezokuthutha nge-electron.
2)Izokuthutha ze-ion.
3) Shaja ukushintshanisa ku-electrolyte/electrode particle interface, okungukuthi, ukusabela kwe-electrochemical.
4) Ukusatshalaliswa kwe-lithium ion ngaphakathi kwesigaba esiqinile. Ku-microstructure yeshidi le-electrode, usayizi wezinhlayiyana nokusabalalisa kuthinta i-lithium{2}}indlela yokusabalalisa ion kanye nendawo ethile yokusabela kwe-electrochemical; usayizi we-pore nokusabalalisa kuthinta inqubo yokuthutha ye-electrolyte; I-porosity ithinta inani lezinto ezisebenzayo kanye nendawo ethile yokusabela kwe-electrochemical. Zonke lezi zici ze-microstructural ekugcineni ziba nomthelela ekusebenzeni kwebhethri.
Isakhiwo se-Cathode
I-cell cathode ikakhulukazi yakhiwe ngezinto ze-cathode ezifana ne-LiCoO₂, i-agent conductive, i-binder (PVDF), kanye nomqoqi wamanje (i-aluminium foil), njengoba kuboniswe kuMfanekiso 7-2.
Kumabhethri e-lithium-ion, i-cathode current collector ivamise ukuba yi-aluminium foil kanye ne-anode current collectorucwecwe lwethusi. Ukuqinisekisa ukuqina komqoqi wamanje ngaphakathi kwebhethri, ubumsulwa bakho bobabili kufanele bube ngaphezu kwama-98%. Izizathu zokuthi kungani amabhethri e-lithium-i-ion asebenzisa i-aluminium foil ye-cathode ne-copper foil ye-anode amaphuzu angu-3 alandelayo:
1) I-Copper ne-aluminium zinokusebenza kahle kukagesi, ukuthungwa okuthambile, kanye nenani eliphansi. Umgomo wokusebenza webhethri le-lithium{2}}i-ion idivayisi ye-electrochemical eguqula amandla amakhemikhali abe amandla kagesi. Kule nqubo, i-medium iyadingeka ukuze kudluliselwe amandla ekhemikhali kumandla kagesi, okudinga into eqhubayo. Phakathi kwezinto ezivamile, izinsimbi zine-conductivity kagesi engcono kakhulu, futhi phakathi kwezinsimbi, ithusi ne-aluminium zinikeza kokubili ukuqhutshwa okuhle kakhulu kanye nentengo ephansi ngendlela ye-foil yethusi ne-aluminium foil. Kumabhethri e-lithium-ion, kunezindlela ezimbili zokucubungula: ukusonga nokupakisha. Uma kuqhathaniswa nokunqwabelanisa, ukujikajika kudinga amashidi e-electrode asetshenziselwa ukulungisa ibhethri ukuze abe nokuguquguquka okuthile ukuze kuqinisekiswe ukuthi amashidi e-electrode awabi brittle noma aphuke ngesikhathi sokusongwa. Phakathi kwezinto zensimbi, ucwecwe lwethusi ne-aluminium luthambile, ucwecwe oluqinile lwethusi/i-aluminium luyabiza, ucwecwe lwethusi ne-aluminium lushibhile uma kuqhathaniswa, kanti izinsiza zethusi ne-aluminium ziningi emhlabeni jikelele.
2) Izicwecwe zethusi ne-aluminium nazo azinzile emoyeni. I-Aluminiyamu ibhekana kalula namakhemikhali nomoya-mpilo osemoyeni ukuze yakhe ifilimu eliminyene le-oxide ngaphezulu, ivimbele ukusabela okwengeziwe kwe-aluminium. Le filimu ye-oxide yethusi/i-aluminium iphinde inikeze umphumela othile wokuvikela ku-aluminium ku-electrolyte. Ithusi ngokwalo lizinzile emoyeni futhi empeleni alihlangani namakhemikhali emoyeni owomile.
3)Amandla e-cathode kanye ne-anode yamabhethri e-lithium-e-ion anquma ukuthi i-aluminium foil isetshenziselwa i-cathode ne-copper foil ye-anode, futhi ayikwazi ukuhlehliswa. Amandla e-cathode aphakeme, futhi i-foil yethusi ifakwa kalula nge-oxidized lapho inamandla aphezulu, kuyilapho i-aluminium inamandla aphezulu oksijini kanye nefilimu ye-oxide eminyene kungqimba lwawo olungaphezulu, olunikeza nokuvikela okuhle kwe-aluminium yangaphakathi.
Ku-crystal lattice ye-aluminiyamu yensimbi, ithusi ne-aluminium kunosayizi abafana no-Li futhi kungakha kalula izinhlanganisela ze-intermetallic no-Li njenge-LiAl. U-Li no-Al abakwazi nje ukwakha ingxubevange ngefomula yamakhemikhali ethi LiAl, kodwa bangase bakhe izendlalelo zengxubevange ye-Li₉Al₄, Li₃Al₂, Li₅Al kanye ne-Li₂Al. Lezi zendlalelo ze-alloy zisebenzisa inani elikhulu le-Li futhi zilimaza ukwakheka ne-morphology ye-Al ngokwayo, ngakho ayikwazi ukusetshenziswa njengomqoqi wamanje we-anode wamabhethri e-lithium{2}}i-ion; kuyilapho i-Cu ihlakazeka kancane kakhulu phakathi nokushajwa kwebhethri-ikhipha futhi igcina ukuqina kwesakhiwo kanye ne-electrochemical, iyenze ifaneleke njengesiqoqi samanje se-anode samabhethri e-lithium{4}}e-ion. Ukuze uthole i-foil yethusi ku-3.5V, i-polarization current iqala ukwanda kakhulu futhi ikhuphuka ngokulandelana, nge-oxidation eqinile, ebonisa ukuthi i-Cu nayo iqala ukuhlakazeka ebhethri; kuyilapho kucwecwe lwe-aluminium kulo lonke uhla olunamandla lwe-polarization, i-polarization yamanje incane futhi izinzile, akukho zenzakalo ezicacile zokugqwala ezibonwayo, ezigcina ukusimama kwe-electrochemical. Njengoba inani lokuqedwa le-Al ebangeni elinamandla le-cathode lamabhethri e-lithium{8}}i-ion lilincane kakhulu futhi ukuqina kwe-electrochemical kungagcinwa, ifaneleka njengeqoqo lamanje le-cathode lamabhethri e-lithium{9}}e-ion.
Isendlalelo se-oxide ezindaweni zethusi/ze-aluminium singesama-semiconductors futhi siqhuba ama-electron; uma ungqimba lwe-oxide likhulu kakhulu, i-impedance inkulu; kuyilapho ungqimba lwe-aluminium oxide endaweni ye-aluminium luyi-insulator futhi alukwazi ukuqhuba ugesi, kodwa ngenxa yokuthi luncane kakhulu, ukuqhutshwa kwe-electron kufinyelelwa ngomphumela womhubhe; uma ungqimba lwe-oxide luwugqinsi, ukuqhutshwa kwe-copper/aluminium foil kumpofu noma ngisho nokuvikela. Ngokuvamile, i-copper/aluminium foil idinga ukuhlanzwa kungqimba lwe-oxide ngaphambi kokusetshenziswa ukususa uwoyela ngakolunye uhlangothi kanye nezingqimba ze-oxide eziwugqinsi ngakolunye. Amandla e-cathode aphezulu, futhi ungqimba lwe-aluminium oxide luminyene kakhulu, olungavimbela i-oxidation yomqoqi wamanje. Izendlalelo ze-oksidi zethusi/ze-nickel njll. azikhululekile, zivimbela kalula isiqoqili samanje futhi zinikeza ukusebenza okungcono kwebhethri. Ngesikhathi esifanayo, amandla e-anode amabhethri e-lithium{5}}e-ion aphansi, futhi i-copper/nickel izobhekana ne-oxidation, nge-oxidation/copper/de-lithiation reactions ezenzeka endaweni yethusi/nickel, kuyilapho i-aluminium idlula i-LiAl alloying ngamandla aphezulu.
Umqoqi wamanje udinga ukwakheka okumsulwa. Ukungcola ku-Al kuzokwenza ifilimu engaphezulu ingabi minyene futhi ibangele ukugqwala komgodi, futhi nakakhulu, ukucekelwa phansi kwefilimu engaphezulu kuholela ekwakhekeni kwe-LiAl alloy.
Umqoqi wamanje udinga ukwakheka okumsulwa. Ukungcola ku-Al kuzobangela ukuthi ifilimu engaphezulu ingabi minyene, okuholela ekugxumeni kwemigodi, futhi okubi nakakhulu, ukucekelwa phansi kwefilimu engaphezulu kuphumela ekwakhekeni kwe-LiAl alloy.
Kumabhethri e-lithium-i-ion, i-cathode aluminium foil yehlisiwe isuka ku-16μm yaya ku-14μm, yabese yaya ku-12μm, futhi manje i-aluminium foil engu-10μm isivele ikhiqizwa ngobuningi, kanti abanye basebenzisa ngisho no-8μm; kucwecwe lethusi le-anode, ngenxa yokuguquguquka okungcono ngokwemvelo, ukujiya kwalo kwehlisiwe kusukela ku-12μm kuya ku-10μm yangaphambilini, bese kuya ku-8μm, futhi okwamanje ingxenye enkulu yamabhethri ayisisindo-akhiqizwa kusetshenziswa u-6μm, kuyilapho abanye abakhiqizi benza u-5μm/4μm nawo okungenzeka asebenziseke. Njengoba amabhethri e-lithium{14}}i-ion anezidingo zokuhlanzeka okuphezulu kwe-foil yethusi esetshenzisiwe, ukuminyana kwezinto ngokuyisisekelo kusezingeni elifanayo. Njengoba ubukhulu obungaphansi kokuthuthukiswa kuncipha, ukuminyana kwe-aal kuncipha ngokufanele, futhi isisindo sebhethri siya siba lula ngokukhanya, okuhlangabezana nesidingo samabhethri e-lithium{16}}ion.
Kubaqoqi bamanje, ngaphezu kogqinsi nesisindo sabo esithinta amabhethri e-lithium-ion, izici ezingaphezulu zesiqoqi samanje nazo zinomthelela omkhulu ekukhiqizweni kwebhethri nokusebenza. Ikakhulukazi kumqoqi wamanje we-anode, ngenxa yokukhubazeka kobuchwepheshe bokulungisa, ama-copper foil emakethe ikakhulukazi anezinhlangothi ezingawodwa-alukhuni,{3}}enziwe rough emaceleni akabili, kanye{4}}nezinhlobo ezimahhala ezikabili. Lesi sakhiwo esinezinhlangothi ezimbili ezi-asymmetric{6}}sizoholela ekuphikisweni kokuthintana kwe-anode ezinhlangothini zombili, ngaleyo ndlela kuvimbele ukukhululwa okufanayo komthamo we-anode nhlangothi zombili; ngesikhathi esifanayo, i-asymmetry kuzo zombili izinhlangothi izophinda ibangele amandla okunamathela angahambisani we-anode coating, okuholela ekushajweni okungalinganiseli kakhulu{7}}impilo yomjikelezo wokukhipha we-anode coating nhlangothi zombili, okubuye kusheshise ukubola komthamo webhethri.
Ukwakhiwa kwe-cathode yeseli eyodwa kuwukhiye oyinhloko wobuchwepheshe beseli. Ngezansi isibonelo:
1)LiCoO₂ (10μm): 96.0%.
2)I-ejenti eqhubayo (i-Carbon ECP): 2.0%.
3)Isibopho (PVDF 761): 2.0%.
4) Umgqugquzeli wokunamathela (NMP): Isilinganiso sesisindo sezinto eziqinile cishe singu-810:1496.
Izinyathelo zokuqapha ukwakheka kwe-cathode:
1)I-Cathode slurry viscosity control ku-6000cP (1cP=1mPa · s) (izinga lokushisa elingu-25 degree).
2)Isisindo se-NMP kufanele silungiswe ngokufanelekile ukuze sihlangabezane nemfuneko ye-viscosity.
3)Naka ngokukhethekile ithonya lokushisa nomswakama ku-viscosity.
I-Cathode material lithium cobalt oxide: I-Cathode esebenzayo, umthombo we-lithium ion, inikeza umthombo we-lithium webhethri. Okungeyona{{1}i-polar, umumo ongajwayelekile, usayizi wezinhlayiyana D50 ngokuvamile u-6-8μm, okuqukethwe komswakama Ngaphansi noma okulingana no-0.2%, ngokuvamile i-alkaline, i-pH 10-11.
I-Cathode impahla ye-lithium manganese oxide: Okungeyona-into ye-polar, umumo ongajwayelekile, usayizi wezinhlayiyana D50 ngokuvamile u-5-7μm, okuqukethwe komswakama Ngaphansi noma okulingana no-0.2%, ngokuvamile i-alkaline ebuthaka, i-pH cishe ngo-8.
I-ejenti eqhubayo: Uchungechunge-njengento, okuqukethwe komswakama<1%, particle size generally 1~5um.Superconductive carbon black with excellent conductivity is usually used, such as KetjenblackCarbon ECP and ECP600JD. lts function is to improve the conductivity of the cathode material,compensate for the electronic conductivity of the cathode active material; increase the electrolyteabsorption of the cathode sheet, expand the reaction interface, and reduce polarization.
I-Binder (PVDF): Okungelona-into ye-polar, iketango-elifana, nesisindo semolekyuli esisuka ku-300000 ukuya ku-3000000; isisindo samangqamuzana siyancipha ngemva kokumuncwa kwamanzi, okubangela ukunamathela okumpofu. Isetshenziselwa ukuhlanganisa i-lithium cobalt oxide, i-ejenti eqhubayo, ne-aluminium foil noma i-aluminium mesh togetherI-Adhesion Promotor (NMP): Uketshezi olupholile olubuthaka, olusetshenziselwa ukuncibilikisa/ukukhukhumeza i-PVDF futhi ngasikhathi sinye kuhlambuluke udaka.
Umqoqi wamanje (ithebhu ye-cathode): Yenziwe nge-aluminium foil noma umugqa we-aluminium.
Isakhiwo se-Anode
Isakhiwo se-anode yeseli siqukethe izinto ze-graphite, i-agent conductive, i-thickener (CMC), i-binder (SBR), kanye nomqoqi wamanje (i-foil yethusi), njengoba kuboniswe kuMfanekiso 7-3.
Ukwakhiwa kwe-anode yeseli elilodwa nakho kungenye yobuchwepheshe obuyinhloko beseli, ngokuvamile obulandelayo:
1) Izinto ze-anode (graphite): 94.5%.
2)I-ejenti eqhubayo (i-Carbon ECP): 1.0% (Ketjenblack).
3)I-Binder (styrene-butadiene rubber latex, SBR): 2.25%.
4) Thickener (carboxymethyl cellulose, CMC): 2.25%.
5) Amanzi: Isilinganiso sesisindo sezinto eziqinile yi-1600: 1417.5.
Izinyathelo zokuqapha ukwakheka kwe-anode:
1) Ukulawulwa kwe-anode slurry viscosity ku-5000-6000cP (izinga lokushisa elingu-25 degree).
2) Isisindo samanzi sidinga ukulungiswa ngokufanele ukuze sihlangabezane nemfuneko ye-viscosity.
3)Naka ngokukhethekile ithonya lokushisa nomswakama ku-viscosity.
I-graphite: I-anode esebenzayo, into eyinhloko eyenza ukusabela kwe-anode, ihlukaniswe kakhulu izigaba ezimbili ezinkulu: i-graphite yemvelo kanye ne-graphite yokwenziwa. Okungeyona{{1}into emhlophe, engcoliswa kalula{2}}yizinto ezingezona ezimhlophe, ezihlakazeka kalula{3}}ezintweni ezingezona ezimhlophe; akulula ukumunca amanzi, futhi akulula ukuwahlakaza emanzini. I-graphite engcolile, ngemva kokuhlakazwa emanzini, ijwayele ukuphinda-i-agglomerate. Usayizi wezinhlayiyana ojwayelekile D50 uzungeze u-20μm. Izimo zezinhlayiya ziyahlukahluka futhi ngokuvamile azifani, ngokuyinhloko ziyindilinga, zigqagqene, zine-fibrous, njll.
Imisebenzi ye-ejenti conductive:
1) Thuthukisa ukuqhutshwa kweshidi le-anode futhi unxephezele ukuqhutshwa kwe-elekthronikhi kwezinto ezisebenzayo ze-anode.
2) Khulisa ukujula kokusabela kanye nezinga lokusebenzisa.
3) Vimbela ukukhiqizwa kwama-dendrites.
4)Sebenzisa uketshezi-umthamo wokumunca wezinto eziphathwayo ukuze ukhuphule isixhumi esibonakalayo futhi unciphise i-polarization (ingangezwa noma cha ngokuya ngokusabalalisa usayizi wezinhlayiyana zegraphite).
Izithasiselo: Yehlisa ukusabela okungenakulungiseka, yandise amandla okubopha kanye ne-viscosity e-slurry, futhi ivimbele ukuvela kwe-slurry sedimentation.
I-Thickener/anti{0}}settling agent (CMC): Inhlanganisela yamamolekyuli aphezulu, ancibilika kalula emanzini nasezincibilikisini ezipholile.
I-Isopropanol: Into ebuthakathaka e-polar; ngemuva kokwengeza, inganciphisa i-polarity yesisombululo se-binder, ithuthukise ukuhambisana phakathi kwesisombululo se-graphite ne-binder; inomphumela onamandla wokukhipha amagwebu; ivuselela kalula-ukuxhumanisa inethiwekhi ye-binder futhi ithuthukise amandla okubopha.
I-Ethanol: Into ye-polar ebuthakathaka; ngemuva kokwengeza, inganciphisa i-polarity yesisombululo se-binder, ithuthukise ukuhambisana phakathi kwesisombululo se-graphite ne-binder; inomphumela onamandla wokukhipha amagwebu; ivuselela kalula i-linear cross-ukuxhumanisa kwe-binder futhi ithuthukise amandla okubopha (imisebenzi ye-isopropanol ne-ethanol iyafana ngokuyinhloko; lapho{1}}ikhiqizwa ngobuningi, izici zezindleko zingacatshangelwa ukuthi zikhethe ukuthi iyiphi ozoyengeza).
-I-binder esekelwe emanzini (SBR): Amabhondi e-graphite, i-conductive agent, izithasiselo, ne-copper foil noma i-copper mesh ndawonye; i-linear chain emulsion molecule, inyibilika kakhulu emanzini nasezincibilikisini ze-polar.
Amanzi ane-deionized (noma amanzi ancibilikisiwe): I-Diluent, engezwe ngenani elifanele, ingashintsha uketshezi lwe-slurry.
Ithebhu ye-anode: Yenziwe nge-foil yethusi noma umugqa wethusi.
