Raws li lub hauv paus nruab nrab rau lithium - ion thauj hauv lub roj teeb, cov electrolyte plays lub luag haujlwm tseem ceeb ntawm "ion conductor," "electrode interface protector," thiab "them hloov choj." Nws qhov ntau yuav tsum nruj me ntsis sib phim rau lub roj teeb lub electrode loj, porosity, thiab encapsulation ntim kom paub meej txaus ntub dej ntawm cov khoom siv hluav taws xob thiab tsis muaj kev cuam tshuam lithium - ion kev thauj mus los. Tsis txaus electrolyte (xa mus rau hauv kev lag luam raws li "hauv-electrolyte") tsis yog ib qho teeb meem ntawm qhov nruab nrab tsis txaus; nws cuam tshuam lub roj teeb sab hauv electrochemical tshuav nyiaj li cas, ua rau muaj kev cuam tshuam ntawm cov saw hlau ua rau kev ua haujlwm tsis zoo thiab kev nyab xeeb tsis ua haujlwm. Feem ntau ntawm qhov kev puas tsuaj no yog irreversible, heev cuam tshuam lub roj teeb lub neej kev pab cuam thiab kev nyab xeeb. Cov kev ntsuam xyuas hauv qab no, raws li cov qauv kev ua haujlwm tiag tiag ntawm cov roj teeb, qhia txog nws cov kev cuam tshuam tshwj xeeb thiab cov txheej txheem hauv qab.
Txhawm rau kom nkag siab meej, cia peb xub piav qhia qhov tseem ceeb ntawm qhov tseem ceeb: Lub luag haujlwm tseem ceeb ntawm electrolyte yog kom yaj lithium ntsev (xws li LiPF6, LiFSI, thiab lwm yam), muab cov lithium ions txav dawb, thaum tib lub sij hawm ntub cov khoom zoo thiab tsis zoo electrode active cov ntaub ntawv (xws li cov ntaub ntawv ternary, lithium hlau graphite, phosphate, thiab lwm yam). Electrolyte / Electrolyte interface (SEI zaj duab xis, CEI zaj duab xis), ua kom muaj txiaj ntsig zoo thiab ruaj khov lithium ion thauj ntawm qhov zoo thiab tsis zoo electrodes.
I. Muaj Peev Xwm Muaj Peev Xwm Tsis Txaus (Low Peev Xwm)
Qhov cuam tshuam ncaj qha thiab nkag siab zoo tshaj plaws ntawm cov hluav taws xob tsis txaus yog tias lub peev xwm tso tawm ntawm lub roj teeb tau qis dua qhov tsim muaj peev xwm, thiab lub peev xwm poob qis yog qhov tsis muaj peev xwm rov qab los, tsis tu ncua zuj zus ntxiv nrog kev nce mus txog qhov suav. Cov txheej txheem tseem ceeb nyob rau hauv qhov tseeb tias qhov zoo thiab qhov tsis zoo ntawm cov khoom siv hluav taws xob tsis tuaj yeem ua tiav los ntawm cov electrolyte; Tsuas yog ib qho me me ntawm cov khoom siv saum npoo av tuaj yeem koom nrog hauv cov tshuaj tiv thaiv lithium ion / rho tawm, thaum lub sij hawm loj ntawm cov khoom siv sab hauv tseem "tsis ua haujlwm" thiab tsis tuaj yeem ua haujlwm electrochemical.
Los ntawm cov qauv kev xav, ob qho tib si zoo thiab tsis zoo electrodes yog ntxeem tau (nrog rau qhov porosity feem ntau ntawm 30% thiab 50%). Cov electrolyte yuav tsum tau ua kom tiav cov pores kom tso cai rau lithium ions tiv tauj txhua yam khoom siv. Yog hais tias cov electrolyte tsis txaus, ib ntus electrolyte tsis tuaj yeem tsim nyob rau hauv lub qhov hws, thiab lithium ions tuaj yeem txav mus rau hauv thaj tsam txwv ntawm qhov chaw electrode. Qhov no txo qis cov lithium ions uas koom nrog cov tshuaj tiv thaiv electrochemical, tiv thaiv kev tso tawm tag nrho cov tsim muaj peev xwm thaum tawm mus.
Tsis tas li ntawd, nyob rau hauv qis -electrolyte lub xeev, thaum lub sij hawm thawj zaug, ib co unwetted active cov ntaub ntawv yuav tsis tsim ib tug ruaj khov interfacial zaj duab xis. Txawm tias tom qab electrolyte ntxiv, cov khoom siv no tsis zoo li yuav rov ua haujlwm, ua rau muaj peev xwm thim rov qab thiab tiv thaiv kev rov qab los rau tus nqi tsim los ntawm kev them nyiaj.
ACEY-BCT560-64PLithium Battery Capacity Testeryog qhov kev daws teeb meem zoo tshaj plaws rau kev sim thiab ntsuas kev ua haujlwm ntawm lithium{0}}ion roj teeb. Lub xeev no - ntawm-- cov khoom siv kos duab muaj cov cuab yeej siv siab tshaj plaws los ntsuas thiab txheeb xyuas ntau yam tsis xws li voltage, tam sim no, kub thiab ntau dua.
II. Sharp nce hauv roj teeb Internal Resistance
Lub sab hauv tsis kam ntawm lub lithium roj teeb feem ntau muaj peb ntu: ohmic tsis kam, them tus nqi hloov pauv, thiab diffusion kuj. Tsis txaus electrolyte ua rau muaj kev nce ntxiv hauv ob qhov kawg, thaum kawg ua rau muaj kev nce siab hauv tag nrho cov roj teeb sab hauv, uas ua rau muaj kev cuam tshuam rau kev them nqi / tso tawm thiab kev ua haujlwm ntawm cov zis.
Ntawm ib sab, nce nqi hloov pauv tsis kam: Kev them nqi hloov pauv feem ntau tshwm sim ntawm electrode / electrolyte interface, tso siab rau cov yeeb yaj kiab interfacial ruaj khov thiab txaus electrolyte rau kev hloov pauv. Thaum electrolyte tsis txaus, lub electrode nto tsis txaus ntub, thiab cov yeeb yaj kiab interfacial (SEI zaj duab xis, CEI zaj duab xis) tsis tuaj yeem npog tsis sib xws. Qhov kev tiv thaiv rau lithium ion ntxig / rho tawm ntawm lub electrode nto nce, ua rau qeeb nqi hloov pauv thiab ua rau cov nqi hloov pauv kom nce exponentially. Ntawm qhov tod tes, nce diffusion tsis kam: Qhov diffusion tus nqi ntawm lithium ions hauv electrolyte yog ncaj qha cuam tshuam nrog kev txuas ntxiv thiab kev xav ntawm electrolyte. Electrolyte tsis txaus ua rau muaj qhov tsis sib xws ntawm electrolyte concentration, nrog rau qee qhov chaw txawm ua "electrolyte-dawb" thaj chaw dawb. Txoj kev diffusion ntawm lithium ions raug thaiv, qhov diffusion nrug ntev dua, thiab diffusion kuj nce ntau.
III. Tseem ceeb heev deteriorating Cycle Performance
Lub voj voog kev ua tau zoo yog qhov taw qhia tseem ceeb ntawm lithium roj teeb lifespan, xa mus rau lub roj teeb lub peev xwm los tuav lub peev xwm ruaj khov thaum rov them dua - tawm mus. Tsis txaus electrolyte ua rau muaj kev puas tsuaj rau lub voj voog kev ua tau zoo thiab ua rau muaj qhov tshwm sim txawv txav xws li kev poob qis thiab tseem ceeb tom qab ib lub voj voog. Qhov no yog qhov tseem ceeb ntawm lub voj voog vicious tshwm sim los ntawm kev muaj zog sab hauv.
Raws li tau hais ua ntej, tsis txaus electrolyte ua rau muaj zog sab hauv. Qhov laj thawj tseem ceeb ntawm kev tiv thaiv sab hauv yog ua kom muaj cua sov hauv cheeb tsam thaum lub sijhawm them roj teeb thiab tso tawm (raws li Joule txoj cai Q=I²Rt, nrog rau qhov tam sim no, siab dua sab hauv ua rau muaj cua sov ntau dua). Localized overheating accelerates electrolyte decomposition- ntawm qhov kub thiab txias, cov electrolyte tau txais cov tshuaj tiv thaiv redox, tsim cov pa roj xws li CO₂ thiab HF, nrog rau cov tshuaj inert, ntxiv cov electrolyte uas tseem tshuav thiab ua rau cov electrolyte tsis txaus. Nyob rau tib lub sijhawm, qhov kub thiab txias kuj tseem ua rau cov yeeb yaj kiab ruaj khov ntawm electrode / electrolyte interface (SEI zaj duab xis yuav tawg thiab rov tsim dua). Lub ruptured SEI zaj duab xis yuav haus lithium ions thiab electrolyte dua los kho nws tus kheej, ntxiv rau kev them nqi hloov mus.
Lub voj voog tsis zoo no ntawm "qis electrolyte qis → nce hauv kev tiv thaiv → cua sov hauv zos → electrolyte decomposition → exacerbated low electrolyte level" ua rau lub roj teeb muaj peev xwm tsis tu ncua thaum caij tsheb kauj vab, thiab tus nqi poob nrawm dua. Thaum tus naj npawb ntawm cov voj voog mus txog ib theem, cov yeeb yaj kiab interfacial ua tsis tiav, lossis cov electrolyte tas lawm, qhov kev poob qis tseem ceeb tshwm sim. Tsis tas li ntawd, qib qis electrolyte kuj ua rau muaj peev xwm tsis sib xws thaum lub roj teeb caij tsheb kauj vab. Hauv ntau- cell series roj teeb pob, cov hlwb uas tsis tshua muaj electrolyte yuav poob ua ntej, yog li rub cov kev ua tau zoo thiab lub neej ntawm tag nrho cov roj teeb.
IV. Kev tsim hluav taws kub hnyav thaum lub sij hawm them nqi thiab tso tawm
Kev tsim hluav taws xob los ntawm cov hluav taws xob tsis txaus yog qhov tseem ceeb ntawm kev ua haujlwm tsis zoo thiab kev nyab xeeb tsis ua haujlwm. Cov hluav taws xob hluav taws xob feem ntau yog los ntawm ob qhov chaw, uas muaj cov txiaj ntsig zoo, ua rau lub roj teeb kub tsis zoo thiab ua rau muaj kev pheej hmoo ntxov ntawm thermal runaway.
- Catalytic Heat Generation Vim Internal Resistance
Raws li tau hais ua ntej, tsis txaus electrolyte ua rau muaj kev nce ntxiv hauv kev tiv thaiv sab hauv, ua rau Joule cua sov ua rau lub sijhawm them thiab tawm. Tsis tas li ntawd, vim tsis muaj cov electrolyte tsis txaus, nws tus kheej lub peev xwm ntawm cov cua sov kuj tseem txo qis (electrolyte kuj muaj qee yam cua sov dissipation muaj nuj nqi, ua hluav taws xob los ntawm electrodes mus rau lub roj teeb casing).
- Kev tsis zoo tshwm sim thaum tshav kub kub
Tsis txaus electrolyte ua rau instability nyob rau hauv lub electrode interface zaj duab xis, ua rau nws muaj kev cuam tshuam sab. Qhov no tshwm sim raws li qhov kub thiab txias ntawm lub roj teeb thaum lub sij hawm them thiab tso tawm (ib txwm nqi thiab tawm kub yog feem ntau 20-45 degree, tab sis tsis txaus cov roj teeb electrolyte yuav nce siab tshaj 50 degree), tshwj xeeb tshaj yog pom thaum them nyiaj, qee zaum txawm tias "kub kov." Yog hais tias lub roj teeb nyob rau hauv tus nqi siab thiab tso tawm, lub tshav kub tsim yuav ua rau muaj zog ntxiv, muaj peev xwm tshaj qhov kub ntawm electrolyte decomposition (feem ntau siab dua 60 degree), ua kom cov electrolyte decomposition thiab electrode aging, tsim kom muaj kev nyab xeeb kev nyab xeeb rau kev ua tsis tiav tom qab. Tsis tas li ntawd, kev tsim hluav taws xob ntev ntev tuaj yeem ua rau lub roj teeb casing deformation thiab sealant aging, uas yuav ua rau electrolyte to thiab ua rau lub roj teeb tsis zoo.
ACEY-BCT506-512Hroj teeb charge discharge test khoomsiv cov cuab yeej siv hluav taws xob niaj hnub saib xyuas thiab tswj cov khoom siv tsis siv phau ntawv ua haujlwm los saib xyuas qhov tiag - lub sijhawm voltage, tam sim no, muaj peev xwm, lub zog, tsim lub xeev thiab lwm yam tsis muaj kev faib roj teeb hauv lub sijhawm, kuaj xyuas thiab tswj qhov tsis raug, sau thiab txheeb xyuas cov ntaub ntawv cuam tshuam, txhawm rau paub txog qhov tsis muaj neeg saib xyuas thiab kev ua haujlwm hauv cov txheej txheem tsim, Khoos phib tawj tswj software rau hauv nruab nrab saib xyuas thiab kho cov khoom siv.
V. Lithium Plating ntawm qhov tsis zoo electrode, lossis Ignition
Qhov no yog qhov cuam tshuam loj tshaj plaws ntawm cov khoom siv hluav taws xob tsis txaus, cuam tshuam ncaj qha rau roj teeb kev nyab xeeb thiab sawv cev rau ib qho ntawm cov qauv kev ua tsis tiav rau hauv qab -electrolyte roj teeb. Qhov laj thawj tseem ceeb ntawm lithium plating yog: tsis txaus electrolyte ua rau cov dej tsis zoo hauv zos ntawm cov hluav taws xob tsis zoo, ua rau tsis sib xws ntawm SEI zaj duab xis. Lithium ions tsis tuaj yeem ua kom zoo nyob nruab nrab ntawm cov graphite txheej thiab tuaj yeem tso cov hlau lithium rau ntawm qhov tsis zoo electrode (piv txwv li, "lithium plating"), ua rau kev sib cuag ncaj qha ntawm qhov zoo thiab tsis zoo electrodes hauv lub roj teeb, ua rau muaj kev cuam tshuam nrog luv luv.
Ib qho hluav taws xob luv luv hauv hluav taws xob tsim hluav taws xob ntau sai sai, ua rau lub roj teeb kub nce siab heev (instantaneously tshaj 100 degree), ua rau thermal runaway. Qhov kub thiab txias ua rau cov electrolyte decompose hnyav heev, ua rau ntau cov nplaim taws thiab tawg (xws li CO thiab CH4). Lub siab sab hauv ntawm lub roj teeb nce siab, thaum kawg ua rau lub roj teeb casing tawg thiab xau. Yog tias cov roj nkag mus rau hauv kev sib cuag nrog huab cua, lossis yog tias qhov kub ntawm sab hauv mus txog qhov hluav taws xob ntawm cov khoom siv hluav taws xob lossis cov khoom siv hluav taws xob, nws tuaj yeem tawg lossis tawg. Tsis tas li ntawd, txawm tias tsis muaj lub voj voog luv luv, cov khoom siv hlau tso rau hauv lithium yuav hnov mob nrog cov electrolyte, siv ob qho tib si electrolyte thiab lithium ions, ntxiv rau kev ua kom lub roj teeb nrawm dua thiab muaj kev nyab xeeb. Thaum disassembling ib lub roj teeb uas tsis txaus electrolyte, nws yog xim hlau lithium deposits tuaj yeem pom ncaj qha rau ntawm qhov chaw tsis zoo electrode, thiab nws yog ignition.
Cov ntsiab lus
Tsis txaus electrolyte nyob rau hauv cov roj teeb lithium tsis yog "qhov tsis xws luag," tab sis ua rau tsis muaj kev puas tsuaj rau lub roj teeb sab hauv, cuam tshuam rau kev ua haujlwm, kev ua neej, thiab kev nyab xeeb. Nws qhov cuam tshuam tau nthuav tawm cov yam ntxwv "cov tshuaj tiv thaiv kab mob" cov yam ntxwv: tsis txaus electrolyte → ntub dej tsis txaus → obstructed lithium ion thauj → nce kev tiv thaiv sab hauv → nce tshav kub → electrolyte decomposition → ua rau tsis txaus electrolyte → lithium deposition → sab hauv luv luv → hluav taws kub thiab tawg. Hauv kev tsim khoom thiab kev siv tiag tiag, tus nqi ntawm cov electrolyte siv yuav tsum tau tswj nruj me ntsis, feem ntau suav tau meej raws li qhov tsis xws li electrode porosity thiab roj teeb ntim kom tsis txhob muaj teeb meem electrolyte tsis txaus.
Yog hais tias lub roj teeb pom kev txo qis hauv ntau yam (muaj peev xwm lwj ntau tshaj 20%), cua kub txawv txav thaum lub sij hawm them thiab tawm, kev them nqi hluav taws xob ntau dhau, tsis tshua muaj hluav taws xob tawm, lossis lub peev xwm poob qis thaum caij tsheb kauj vab, nws yuav qhia tau tias tsis muaj electrolyte. Kev tshuaj xyuas raws sijhawm thiab kev saib xyuas yog qhov tseem ceeb los tiv thaiv kev puas tsuaj roj teeb ntxiv lossis teeb meem kev nyab xeeb. Rau cov roj teeb loj xws li cov roj teeb hluav taws xob thiab cov roj teeb lub zog, cov khoom siv hluav taws xob tsis txaus kuj tuaj yeem cuam tshuam rau kev ruaj ntseg ntawm tag nrho lub cev, yuav tsum tau ua tib zoo saib xyuas thiab tiv thaiv.
