Roj teeb Peev Xwm Degradation Mechanism yog dab tsi?
Hloov hauv cov khoom siv
Cov khoom siv cathode tam sim no feem ntau suav nrog cov qauv hexagonal txheej ntawm LiMO2 (qhov twg M=Co, Ni, Mn), cov qauv spinel ntawm LiMn2O4, thiab cov qauv olivine ntawm LiFePO4. Tsis hais txog ntawm cov qauv, thaum lithium ions deintercalate los ntawm cathode, kom tswj tau cov hluav taws xob hauv cov khoom siv, cov khoom siv hlau yog inevitably oxidized mus rau lub xeev siab dua, uas yog nrog los ntawm cov txheej txheem hloov mus rau theem. Kev hloov pauv feem ntau ua rau cov theem hloov pauv, yog li lithium ions txuas ntxiv txuas ntxiv thiab deintercalate hauv cov khoom, cov theem hloov mus txuas ntxiv, thiab ntev mus, nws yuav ua rau muaj kev hem thawj rau cov khoom siv lead ua. Piv nrog rau cov anode, qhov tsis sib npaug ntawm qhov rov qab muaj peev xwm tshwm sim los ntawm kev hloov pauv theem thiab kev hloov pauv ntawm cov qauv ntawm cov khoom siv cathode muaj qhov cuam tshuam loj rau lub roj teeb lub neej. Graphite muaj txheej txheej txheej. Thaum nws yog ob peb khaubncaws sab nraud povtseg, lithium ions intercalate rau hauv lub interlayers thaum lub sij hawm lub roj teeb them thiab ua ke nrog electrons thauj los ntawm sab nraud Circuit Court los ua lithiated graphite, thiab lub interlayer spacing nce nyob rau lub sij hawm no; Thaum lub sij hawm tso tawm, lithium ions tawm hauv graphite interlayers thiab tso cov hluav taws xob mus rau sab nraud Circuit Court, tab tom ua rau deintercalation thiab oxidation cov tshuaj tiv thaiv, thiab cov interlayer spacing txo nyob rau lub sij hawm no.
Dissolution ntawm Active Khoom
Lub dissolution ntawm cov khoom cathode yog hais txog cov txheej txheem uas cov khoom siv maj mam txo qis vim yog corrosion hauv electrolyte. Kev tawg ntawm cov khoom siv cathode ntawm qhov kub thiab txias yog ib qho ntawm cov laj thawj rau lub roj teeb muaj peev xwm lwj, tshwj xeeb tshaj yog muaj kev cuam tshuam ntau dua rau kev ua haujlwm ntawm lub voj voog thiab kev cia khoom ntawm cov roj teeb ntawm qhov kub thiab txias. Kev tawg ntawm cov hlau hloov pauv nyob rau hauv qee yam kev mob yog ib qho teeb meem uas muaj nyob rau hauv tag nrho cov ntaub ntawv LiMO2 cathode. Cov laj thawj tseem ceeb vim li cas qhov kev sib cais ntawm cov khoom nquag ua rau lub roj teeb tsis zoo yog: $\\textcircled{1}$ Kev tawg ntawm cov khoom hlau ncaj qha ua rau txo cov khoom siv hluav taws xob, ua rau lub roj teeb poob; $\\textcircled{2}$ Lub dissolution ntawm cathode cov ntaub ntawv ua rau degradation ntawm cov khoom qauv thiab tsim ntawm chemically inactive tshuaj nyob rau saum npoo ntawm cov khoom, uas cuam tshuam kev thauj ntawm lithium ions nyob rau hauv cov khoom siv electrode; $\\textcircled{3}$ Cov solvated hlau ions muaj nyob rau hauv cov electrolyte tsiv mus rau lub anode nyob rau hauv lub electrolyte thiab tso rau ntawm lub anode nto nyob rau hauv daim ntawv ntawm hlau los yog ntsev nyob rau hauv uas tsis muaj peev xwm, thiab cov deposits inevitably cuam tshuam lub stability thiab thickness ntawm SEI zaj duab xis nyob rau hauv lub anode nto, ua rau kom electrode nto polarization thiab muaj zog roj teeb nyob rau hauv tsis kam. Yog li ntawd, cov nyhuv ntawm cov khoom siv hluav taws xob tawg ntawm cov electrolyte tsis tsuas yog los ntawm kev tawg, tab sis kuj los ntawm kev cuam tshuam ntau ntxiv los ntawm kev tawg ntawm cov hlau hloov pauv.
Kev siv cov lithium ions
Hauv kev tsim cov roj teeb lithium-ion roj teeb, lub peev xwm ntawm lub roj teeb feem ntau yog me ntsis ntau dua li ntawm cov cathode, thiab cov lithium ions rov ua dua tau muab los ntawm cathode. Yog li ntawd, qhov thim rov qab intercalation thiab deintercalation ntawm lithium ions ntawm cathode thiab anode txiav txim siab lub peev xwm roj teeb. Thaum lub sij hawm thawj tus nqi thiab tawm cov txheej txheem, ib zaj duab xis SEI yog tsim rau ntawm qhov chaw anode. Cov khoom tseem ceeb ntawm zaj duab xis passivation no yog ntau yam inorganic tshuaj xws li Li2CO3, LiF, Li2O, LiOH thiab ntau yam organic Cheebtsam xws li ROCO2Li, ROLi, thiab (ROCO2) 2Li. Yog li, qee qhov lithium ions tau noj, thiab qhov kev poob peev no tsis tuaj yeem rov qab los. Qhov kev ua tau zoo ntawm cov anode muaj feem xyuam rau cov morphology thiab stability ntawm SEI zaj duab xis, thiab lub peev xwm los tsim ib tug ruaj khov SEI zaj duab xis nyob rau hauv anode nto muaj ib tug tsis muaj kev cuam tshuam rau cov roj teeb kev ua tau zoo. Kev tsim ntawm SEI zaj duab xis siv cov lithium ions tsawg hauv lub roj teeb. Yog tias SEI zaj duab xis raug puas tsuaj tas li thaum lub voj voog, tom qab ntawd cov tshuaj tiv thaiv oxidation ntawm anode / electrolyte interface yuav tshwm sim tsis tu ncua los tsim ib zaj duab xis SEI tshiab. Cov txheej txheem no siv cov lithium ions tsawg uas muab los ntawm cathode hauv lub cev, thiab qhov txo qis ntawm lithium ions ua rau muaj peev xwm lwj. Kev txo qis ntawm lithium ions hauv electrolyte ua rau txo qis ntawm cov electrolyte, thiab qhov poob ntawm lithium ions hauv cov khoom siv cathode ua rau muaj qhov tsis sib xws ntawm ob lub electrodes ntawm lub roj teeb.
Nce hauv Internal Resistance
Thaum lub sij hawm ntev - lub sij hawm caij tsheb kauj vab ntawm lub roj teeb, qhov nce hauv kev tiv thaiv sab hauv kuj yog ib qho laj thawj tseem ceeb rau lub peev xwm lwj. Muaj ntau qhov laj thawj rau kev nce hauv kev tiv thaiv sab hauv, feem ntau yog los ntawm ob yam: $\\textcircled{1}$ Cov tshuaj tiv thaiv oxidation tshwm sim ntawm electrode / electrolyte interface hauv electrolyte ua rau muaj kev nce hauv cov yeeb yaj kiab tiv thaiv ntawm electrode, thiab qhov tsis ruaj khov ntawm anode SEI zaj duab xis, txuas ntxiv tsim cov yeeb yaj kiab tshiab hauv lub voj voog, thiab lwm yam, tag nrho cov roj teeb muaj zog; $\\textcircled{2}$ Cov yaj ntawm cov hlau ions hauv cathode rau hauv cov electrolyte, thiab cov yaj ionized hlau ions tsiv mus rau lub anode los ntawm electrolyte thiab tso rau ntawm qhov chaw anode nyob rau hauv daim ntawv ntawm hlau los yog ntsev, ua rau muaj zog electrode polarization. Tsis tas li ntawd, kev tshawb fawb kuj tau ua pov thawj tias qhov corrosion ntawm cov khoom siv tam sim no kuj tuaj yeem ua rau muaj kev cuam tshuam sab hauv, tab sis cov nyhuv no kuj me me nyob rau hauv qhov chaw ntawm pretreatment ntawm cov khoom tam sim no. Qhov nce hauv kev tiv thaiv sab hauv ua rau txo qis zog thiab muaj peev xwm, tshwj xeeb tshaj yog rau cov anode, cov tshuaj tiv thaiv tshwm sim ntawm electrode / electrolyte interface yog qhov laj thawj tseem ceeb rau anode aging.
