Iyini Indlela Yokwehliswa Komthamo Webhethri?
Ushintsho Kusakhiwo Sezinto
Izinto zamanje ze-cathode ezisetshenziswa kakhulu ikakhulukazi zifaka ukwakheka kwe-LiMO2 enezingqimba eziyi-hexagonal (lapho i-M=Co, Ni, Mn), ukwakheka kwe-spinel ye-LiMn2O4, kanye nesakhiwo se-olivine se-LiFePO4. Kungakhathaliseki ukuthi isakhiwo sinjani, lapho i-lithium ion ihlukana ne-cathode, ukuze kugcinwe isimo sikagesi endabeni, i-metal element i-oxidized nakanjani ibe yi-valence ephakeme, ehambisana nenqubo yokuguqulwa kwesigaba. Ukuguqulwa kwesigaba kuvame ukuholela ekushintsheni kwesigaba, ngakho-ke njengoba i-lithium ion iqhubeka ihlangana futhi ihlukanisa phakathi kwezinto, ukuguqulwa kwesigaba kuyaqhubeka, futhi ngokuhamba kwesikhathi, kuzobeka usongo ekuzinzeni kwekristalu. Uma kuqhathaniswa ne-anode, umthamo ongalingani obuyiselekayo obangelwa ukushintsha kwesigaba kanye nezinguquko kusakhiwo senqwaba yezinto ezisetshenziswayo ze-cathode kunomthelela omkhulu empilweni yebhethri. I-graphite inesakhiwo esinezingqimba. Uma iwugqinsi izingqimba eziningana, ama-ion e-lithium ahlangana phakathi kwezihlanganisi ngesikhathi sokushajwa kwebhethri futhi ahlanganiswe nama-electron ahanjiswa esuka kumjikelezo wangaphandle ukuze akhe i-lithiated graphite, futhi ukuhlukana kwe-interlayer kuyanda ngalesi sikhathi; ngesikhathi sokukhishwa, ama-ion e-lithium ashiya ama-graphite interlayers futhi akhulule ama-electron kumjikelezo wangaphandle, abhekana nokuphendula kwe-deintercalation kanye ne-oxidation, futhi isikhala se-interlayer siyancipha ngalesi sikhathi.
Ukuqedwa Kwezinto Ezisebenzayo
Ukuhlakazwa kwe-cathode material kubhekisela enqubweni lapho into esebenzayo iyancipha kancane kancane ngenxa yokugqwala ku-electrolyte. Ukuhlakazwa kwempahla ye-cathode emazingeni okushisa aphezulu kungesinye sezizathu zokubola kwamandla ebhethri, ikakhulukazi okunomthelela omkhulu ekusebenzeni komjikelezo nokusebenza kokugcinwa kwamabhethri emazingeni okushisa aphezulu. Ukuhlakazwa kwezinsimbi eziguqukayo ngaphansi kwezimo ezithile kuyinkinga ekhona kuzo zonke izinto ze-cathode ze-LiMO2. Izizathu eziyinhloko zokuthi kungani ukuhlakazwa kwezinto ezisebenzayo kuholela ekulimaleni kokusebenza kwebhethri yilezi: $\\textcircled{1}$ Ukuhlakazwa kwezinto zensimbi kuholela ngokuqondile ekuncishisweni kwezinto ezisebenzayo, okubangela ukulahlekelwa amandla ebhethri; $\\textcircled{2}$ Ukuqedwa kwezinto ze-cathode kubangela ukuwohloka kwesakhiwo sezinto ezibonakalayo kanye nokwakheka kwezinto ezingasebenzi ngamakhemikhali ebusweni bezinhlayiya, okuvimbela ukuthuthwa kwe-lithium ion ku-electrode material; $\\textcircled{3}$ Ama-ion ensimbi ancibilikisiwe aqukethwe ku-electrolyte athuthela ku-anode ku-electrolyte futhi abeke endaweni ye-anode ngendlela yensimbi noma usawoti ngaphansi kwamandla aphansi, futhi lezi zidiphozithi zithinta ngokungenakugwenywa ukuzinza nokujiya kwefilimu ye-SEI endaweni ye-anode, okuholela ekukhuleni kwe-electrode surface polarization kanye nokwanda kokumelana nebhethri kwangaphakathi. Ngakho-ke, umthelela wokuhlakazeka kwezinto ezisebenzayo ku-electrolyte awuveli nje kuphela ekuhlakazweni kodwa futhi uvela emiphumeleni emibi kakhulu elethwa ukuhlakazwa kwezinsimbi eziguqukayo.
Ukusetshenziswa kwe-Lithium ions
Edizayini yamabhethri e-lithium-i-ion, umthamo webhethri uvamise ukuba ngaphezudlwana kwawe-cathode, futhi ama-ion e-lithium asebenziseka kabusha ahlinzekwa yi-cathode. Ngakho-ke, ukuhlangana okubuyiselekayo emuva kanye nokuhlukaniswa kwe-lithium ion phakathi kwe-cathode ne-anode kunquma umthamo webhethri. Phakathi nenqubo yokuqala yokushaja nokukhipha, kwakheka ifilimu ye-SEI endaweni ye-anode. Izingxenye eziyinhloko zale filimu ye-passivation yizinto ezihlukahlukene ze-inorganic ezifana ne-Li2CO3, i-LiF, i-Li2O, i-LiOH kanye nezingxenye ezihlukahlukene ze-organic ezifana ne-ROCO2Li, i-ROLi, ne-(ROCO2)2Li. Ngakho-ke, amanye ama-ion e-lithium ayasetshenziswa, futhi lokhu kulahlekelwa umthamo akunakuhlehliswa. Ukusebenza kwe-anode kuhlobene kakhulu ne-morphology nokuzinza kwefilimu ye-SEI, kanye nekhono lokwenza ifilimu ye-SEI ezinzile endaweni ye-anode inomthelela{12}ongenakuqhathaniswa nokusebenza kwebhethri. Ukwakhiwa kwefilimu ye-SEI kudla ama-ion e-lithium alinganiselwe ebhethrini. Uma ifilimu ye-SEI ilimala ngokuqhubekayo phakathi nomjikelezo, khona-ke ukusabela kwe-oxidation kusixhumi esibonakalayo se-anode/electrolyte kuzokwenzeka ngokuqhubekayo ukuze kwakhe ifilimu entsha ye-SEI. Le nqubo idla ama-ion e-lithium alinganiselwe anikezwe i-cathode ohlelweni, futhi ukuncishiswa kwe-lithium ion esebenzayo kuholela ekuboleni kwamandla. Ukuncishiswa kwe-lithium ion ku-electrolyte kuholela ekwehleni kokusebenza kwe-electrolyte, futhi ukulahleka kwe-lithium ion ku-cathode material kubangela ukungalingani phakathi kwama-electrode amabili ebhethri.
Khuphula Ukumelana Kwangaphakathi
Phakathi-nokuhamba ngebhayisikili kwesikhathi eside kwebhethri, ukwenyuka kokumelana kwangaphakathi nakho kuyisizathu esibalulekile sokubola kwamandla. Kunezizathu eziningi zokwenyuka kokungazweli kwangaphakathi, ikakhulukazi ezicini ezimbili: $\\textcircled{1}$ Ukusabela kwe-oxidation okwenzeka kusixhumi esibonakalayo se-electrode/electrolyte ku-electrolyte kuholela ekwenyukeni kokumelana nefilimu engaphezulu kwe-electrode, kanye nokungaqini kwefilimu ye-anode SEI, kwakheka amafilimu amasha angaphezulu phakathi nomjikelezo, njll. $\\textcircled{2}$ Ukuncibilika kwama-ion ensimbi ku-cathode ku-electrolyte, futhi ama-ion ensimbi e-ionized encibilikile athuthele ku-anode nge-electrolyte futhi afake endaweni ye-anode ngendlela yensimbi noma usawoti, okuholela ekwandeni kwe-electrode polarization. Ngaphezu kwalokho, ucwaningo luye lwafakazela nokuthi ukugqwala komqoqi wamanje nakho kungaholela ekwandeni kokumelana kwangaphakathi, kodwa lo mphumela uncane kakhulu ngaphansi kwesisekelo sokuphathwa kwangaphambili komqoqi wamanje. Ukwenyuka kokumelana kwangaphakathi kuholela ekwehleni kokuqina kwamandla namandla, ikakhulukazi ku-anode, ukusabela okwenzeka ku-interface ye-electrode/electrolyte yisizathu esiyinhloko sokuguga kwe-anode.
