Vim li cas lub roj teeb lithium hlau phosphate poob?

Kev nkag siab txog qhov ua rau lossis kev ua haujlwm tsis ua haujlwm ntawm cov roj teeb lithium hlau phosphate yog qhov tseem ceeb heev rau kev txhim kho cov roj teeb kev ua haujlwm thiab nws cov khoom loj thiab siv. Kab lus no tham txog qhov cuam tshuam ntawm impurities, tsim txoj hauv kev, cia tej yam kev mob, rov ua dua, overcharge, thiab over-discharge ntawm roj teeb tsis ua hauj lwm.

1. Ua tsis tiav hauv cov txheej txheem tsim khoom

Hauv cov txheej txheem tsim khoom, cov neeg ua haujlwm, cov khoom siv, cov khoom siv raw, cov txheej txheem, thiab ib puag ncig yog qhov tseem ceeb uas cuam tshuam rau cov khoom zoo. Hauv cov txheej txheem tsim khoom ntawm LiFePO4 cov roj teeb hluav taws xob, cov neeg ua haujlwm thiab cov khoom siv tau koom nrog kev tswj hwm, yog li peb feem ntau tham txog peb qhov cuam tshuam kawg.

Lub impurity nyob rau hauv cov khoom siv electrode ua rau lub roj teeb tsis ua haujlwm.

Thaum lub sij hawm synthesis ntawm LiFePO4, yuav muaj ib tug me me ntawm impurities xws li Fe2O3 thiab Fe. Cov impurities no yuav raug txo nyob rau saum npoo ntawm qhov tsis zoo electrode thiab tej zaum yuav tho lub diaphragm thiab ua rau ib tug luv luv Circuit Court. Thaum LiFePO4 raug rau huab cua ntev, noo noo yuav deteriorate lub roj teeb. Nyob rau hauv thaum ntxov theem ntawm kev laus, amorphous hlau phosphate yog tsim nyob rau saum npoo ntawm cov khoom. Nws cov qauv hauv zos thiab cov qauv zoo ib yam li LiFePO4 (OH); Nrog rau kev nkag ntawm OH, LiFePO4 tau noj tas li, tshwm sim raws li qhov nce hauv ntim; tom qab recrystallized maj mam tsim LiFePO4 (OH). Li3PO4 impurity hauv LiFePO4 yog electrochemically inert. Qhov siab dua cov ntsiab lus impurity ntawm graphite anode, ntau dua qhov tsis muaj peev xwm poob.

Qhov tsis ua hauj lwm ntawm lub roj teeb los ntawm txoj kev tsim

Lub irreversible poob ntawm active lithium ions yog thawj pom nyob rau hauv lub lithium ions noj thaum tsim cov khoom electrolyte interfacial membrane. Cov kev tshawb fawb tau pom tias qhov nce qhov kub thiab txias yuav ua rau muaj kev poob qis dua lithium ions. Thaum qhov kub ntawm qhov tsim tau nce, qhov kev faib ua feem ntawm inorganic Cheebtsam hauv SEI zaj duab xis yuav nce. Cov roj tso tawm thaum lub sij hawm hloov pauv ntawm cov organic ib feem ROCO2Li mus rau inorganic tivthaiv Li2CO3 yuav ua rau ntau yam tsis xws luag hauv SEI zaj duab xis. Ib tug loj tus naj npawb ntawm lithium ions daws los ntawm cov teeb meem no yuav embedded nyob rau hauv qhov tsis zoo graphite electrode.

Thaum lub sij hawm tsim, muaj pes tsawg leeg thiab tuab ntawm SEI zaj duab xis tsim los ntawm cov nqi qis tam sim no yog ib yam tab sis siv sijhawm ntev; Kev them nyiaj tam sim no yuav ua rau muaj kev cuam tshuam ntau ntxiv, uas ua rau muaj kev cuam tshuam tsis zoo lithium-ion poob thiab qhov tsis zoo electrode interface impedance kuj yuav nce, tab sis nws txuag lub sijhawm. Lub sij hawm; Niaj hnub no, kev tsim hom me me tsis tu ncua tam sim no-loj tam sim no tsis tu ncua thiab qhov hluav taws xob tsis tu ncua yog siv ntau zaus kom nws tuaj yeem coj qhov zoo ntawm ob qho tib si rau hauv tus account.

Roj teeb tsis ua hauj lwm tshwm sim los ntawm noo noo nyob rau hauv qhov chaw tsim khoom

Hauv kev tsim khoom tiag tiag, lub roj teeb yuav inevitably hu rau huab cua vim tias cov ntaub ntawv zoo thiab tsis zoo yog feem ntau micron lossis nano-loj hais, thiab cov kuab tshuaj molecules hauv electrolyte muaj cov electronegative carbonyl pawg loj thiab metastable carbon-carbon ob daim ntawv cog lus. Txhua yam yooj yim nqus dej noo hauv huab cua.

Cov dej molecules reacts nrog lithium ntsev (tshwj xeeb tshaj yog LiPF6) nyob rau hauv lub electrolyte, uas decomposes thiab noj cov electrolyte (decomposes rau PF5) thiab tsim cov acidic HF. Ob leeg PF5 thiab HF yuav rhuav tshem SEI zaj duab xis, thiab HF tseem yuav txhawb nqa qhov corrosion ntawm LiFePO4 cov khoom nquag. Cov dej molecules tseem yuav delithiate lithium-intercalated graphite tsis zoo electrode, tsim lithium hydroxide nyob rau hauv qab ntawm SEI zaj duab xis. Tsis tas li ntawd, O2 yaj nyob rau hauv cov electrolyte tseem yuav ua kom cov laus ntawm LiFePO4 roj teeb.

Hauv cov txheej txheem tsim khoom, ntxiv rau cov txheej txheem tsim khoom uas cuam tshuam rau lub roj teeb kev ua tau zoo, lub ntsiab tseem ceeb uas ua rau tsis ua haujlwm ntawm LiFePO4 lub zog roj teeb suav nrog cov impurities hauv cov khoom siv raw (xws li dej) thiab cov txheej txheem tsim, yog li cov purity ntawm cov khoom siv raw. cov khoom siv, kev tswj ntawm ib puag ncig cov av noo, txoj kev tsim, thiab lwm yam. Cov khoom tseem ceeb heev.

2. Ua tsis tiav hauv txee

Thaum lub sij hawm kev pab cuam lub neej ntawm lub hwj chim roj teeb, feem ntau ntawm nws lub sij hawm nyob rau hauv lub xeev ntawm txee. Feem ntau, tom qab lub sijhawm ua haujlwm ntev, lub roj teeb kev ua haujlwm yuav txo qis, feem ntau qhia tias muaj kev tiv thaiv sab hauv, txo qhov voltage, thiab txo qhov muaj peev xwm tawm. Ntau yam ua rau muaj kev puas tsuaj ntawm cov roj teeb ua haujlwm, ntawm qhov kub, lub xeev ntawm tus nqi, thiab lub sijhawm yog qhov cuam tshuam zoo tshaj plaws.

Kassem et al. txheeb xyuas qhov kev laus ntawm LiFePO4 lub zog roj teeb nyob rau hauv cov xwm txheej sib txawv. Lawv ntseeg hais tias cov txheej txheem kev laus feem ntau yog cov tshuaj tiv thaiv sab ntawm cov electrodes zoo thiab tsis zoo. Cov electrolyte (piv rau sab cov tshuaj tiv thaiv ntawm qhov zoo electrode, sab cov tshuaj tiv thaiv ntawm qhov tsis zoo graphite electrode yog hnyav dua, feem ntau tshwm sim los ntawm cov kuab tshuaj decomposition, kev loj hlob ntawm SEI zaj duab xis) noj lithium ions nquag. Nyob rau tib lub sijhawm, tag nrho impedance ntawm lub roj teeb nce, qhov poob ntawm cov lithium ions nquag ua rau lub roj teeb kev laus thaum nws tawm mus. Lub peev xwm poob ntawm LiFePO4 roj teeb lub zog nce nrog qhov nce ntawm qhov kub thiab txias. Nyob rau hauv sib piv, raws li lub xeev cia ntawm tus nqi nce, lub peev xwm poob yog ntau me.

Grolleau et al. kuj tau mus txog tib qhov kev txiav txim siab: qhov ntsuas kub cia muaj qhov cuam tshuam loj dua rau kev laus ntawm LiFePO4 roj teeb lub zog, ua raws li lub xeev cia ntawm tus nqi, thiab cov qauv yooj yim yog npaj. Nws tuaj yeem kwv yees lub peev xwm poob ntawm LiFePO4 lub zog roj teeb raws li qhov muaj feem xyuam nrog lub sijhawm cia (kub thiab lub xeev ntawm tus nqi). Nyob rau hauv ib lub xeev SOC tshwj xeeb, raws li lub sij hawm txee nce, lub lithium nyob rau hauv lub graphite yuav diffuse mus rau lub ntug, tsim ib tug complex compound nrog cov electrolyte thiab electrons, uas ua rau ib tug nce nyob rau hauv qhov kev faib ua feem ntawm irreversible lithium ions, thickening ntawm SEI, thiab conductivity. Qhov nce ntawm impedance tshwm sim los ntawm qhov txo qis (cov khoom siv tsis muaj zog nce ntxiv, thiab qee qhov muaj lub sijhawm rov ua kom rov ua dua) thiab qhov txo qis ntawm cov electrode nto ua haujlwm ua ke ua rau lub roj teeb muaj kev laus.

Txawm hais tias lub xeev them nyiaj lossis lub xeev tso tawm, qhov sib txawv scanning calorimetry tsis pom muaj cov tshuaj tiv thaiv ntawm LiFePO4 thiab cov electrolytes sib txawv (cov electrolyte yog LiBF4, LiAsF6, lossis LiPF6) nyob rau hauv qhov kub ntawm chav tsev kub txog 85 ° C. Txawm li cas los xij, thaum LiFePO4 yog immersed nyob rau hauv cov electrolyte ntawm LiPF6 rau lub sij hawm ntev, nws tseem yuav pom cov reactivity tshwj xeeb. Vim hais tias cov tshuaj tiv thaiv los tsim cov kev sib tshuam ntev, tseem tsis muaj zaj duab xis passivation ntawm LiFePO4 los tiv thaiv cov tshuaj tiv thaiv ntxiv nrog cov electrolyte tom qab immersing rau ib hlis.

Nyob rau hauv lub xeev txee, tsis zoo cia tej yam kev mob (siab kub thiab siab lub xeev ntawm tus nqi) yuav ua rau kom lub degree ntawm tus kheej-tso tawm ntawm lub LiFePO4 lub hwj chim roj teeb, ua rau lub roj teeb aging ntau pom tseeb.

3. Ua tsis tiav hauv kev rov ua dua tshiab

Cov roj teeb feem ntau tso cov cua sov thaum siv, yog li qhov kub ntawm qhov ntsuas kub yog qhov tseem ceeb. Tsis tas li ntawd, txoj kev, kev siv, thiab qhov kub thiab txias yuav muaj qhov sib txawv.

Kev poob ntawm cov lithium ions feem ntau ua rau lub peev xwm poob ntawm LiFePO4 roj teeb lub zog thaum caij tsheb kauj vab. Dubarry et al. qhia tau hais tias kev laus ntawm LiFePO4 roj teeb lub zog thaum caij tsheb kauj vab yog vim muaj cov txheej txheem kev loj hlob uas siv cov lithium-ion SEI zaj duab xis ua haujlwm. Nyob rau hauv cov txheej txheem no, qhov poob ntawm active lithium ions ncaj qha txo tus nqi tuav ntawm lub roj teeb muaj peev xwm; kev loj hlob tsis tu ncua ntawm SEI zaj duab xis, ntawm ib sab, ua rau muaj kev nce hauv polarization tsis kam ntawm lub roj teeb. Nyob rau tib lub sijhawm, lub thickness ntawm SEI zaj duab xis yog tuab heev, thiab electrochemical kev ua tau zoo ntawm graphite anode. Nws yuav ua rau qee qhov tsis ua haujlwm.

Thaum lub caij kub kub, Fe2+ hauv LiFePO4 yuav yaj mus rau ib qho twg. Txawm hais tias tus nqi ntawm Fe2 + yaj tsis muaj qhov cuam tshuam loj rau lub peev xwm ntawm qhov zoo electrode, qhov kev sib cais ntawm Fe2 + thiab nag lossis daus ntawm Fe ntawm qhov tsis zoo graphite electrode yuav ua lub luag haujlwm catalytic hauv kev loj hlob ntawm SEI zaj duab xis. . Tan quantitatively soj ntsuam qhov twg thiab qhov twg cov active lithium ions tau ploj thiab pom tias feem ntau ntawm cov active lithium ions tshwm sim nyob rau saum npoo ntawm qhov tsis zoo graphite electrode, tshwj xeeb tshaj yog thaum lub sij hawm kub-kub cycles, uas yog, lub high-temperature voj voog muaj peev xwm poob. yog sai dua, thiab cov ntsiab lus ntawm SEI zaj duab xis Muaj peb yam sib txawv ntawm kev puas tsuaj thiab kho:

1. Cov electrons hauv graphite anode dhau los ntawm SEI zaj duab xis kom txo cov lithium ions.
2. Kev tawg thiab rov tsim dua tshiab ntawm qee cov khoom ntawm SEI zaj duab xis.
3. Vim lub ntim hloov ntawm graphite anode, SEI membrane yog tshwm sim los ntawm rupture.

Ntxiv nrog rau qhov poob ntawm cov lithium ions nquag, ob qho tib si zoo thiab tsis zoo cov ntaub ntawv yuav deteriorate thaum rov ua dua. Qhov tshwm sim ntawm cov kab nrib pleb hauv LiFePO4 electrode thaum rov ua dua yuav ua rau cov electrode polarization nce ntxiv thiab cov khoom siv hluav taws xob thiab cov khoom siv hluav taws xob lossis cov khoom siv tam sim no txo ​​qis. Nagpure siv Scanning Extended Resistance Microscopy (SSRM) mus rau ib nrab-quantitatively kawm cov kev hloov ntawm LiFePO4 tom qab laus thiab pom tias coarsening ntawm LiFePO4 nanoparticles thiab nto deposits uas tsim los ntawm tej yam tshuaj tiv thaiv ua ke ua rau ib tug nce nyob rau hauv lub impedance ntawm LiFePO4 cathodes. Tsis tas li ntawd, qhov txo qis ntawm qhov chaw ua haujlwm thiab exfoliation ntawm graphite electrodes tshwm sim los ntawm kev poob ntawm cov khoom siv graphite kuj suav tias yog qhov ua rau lub roj teeb aging. Lub instability ntawm graphite anode yuav ua rau lub instability ntawm SEI zaj duab xis thiab txhawb kev noj ntawm active lithium ions.

Lub roj teeb uas muaj peev xwm ua tau zoo tuaj yeem muab lub zog tseem ceeb rau lub tsheb fais fab; uas yog, qhov zoo dua qhov kev ua tau zoo ntawm cov roj teeb fais fab, qhov zoo dua qhov kev ua haujlwm nrawm ntawm lub tsheb fais fab. Cov txiaj ntsig tshawb fawb ntawm Kim et al. qhia tau hais tias cov txheej txheem kev laus ntawm LiFePO4 zoo electrode thiab graphite tsis zoo electrode yog txawv: nrog rau qhov nce ntawm qhov paug tawm, lub peev xwm poob ntawm qhov zoo electrode nce ntau dua li qhov tsis zoo electrode. Kev poob ntawm cov roj teeb muaj peev xwm thaum lub caij qis qis yog feem ntau yog vim kev noj cov lithium ions nyob rau hauv qhov tsis zoo electrode. Nyob rau hauv sib piv, lub hwj chim poob ntawm lub roj teeb thaum lub sij hawm high-rate cycling yog vim lub nce nyob rau hauv lub impedance ntawm lub zoo electrode.

Txawm hais tias qhov tob ntawm qhov tso tawm ntawm lub hwj chim roj teeb hauv kev siv yuav tsis cuam tshuam rau lub peev xwm poob, nws yuav cuam tshuam rau nws lub zog poob: qhov ceev ntawm lub zog poob nce nrog qhov nce ntawm qhov tob ntawm qhov paug. Qhov no yog vim qhov nce hauv impedance ntawm SEI zaj duab xis thiab qhov nce hauv impedance ntawm tag nrho cov roj teeb. Nws yog ncaj qha ntsig txog. Txawm hais tias tus txheeb ze rau qhov poob ntawm cov lithium ions, qhov kev txwv sab saud ntawm qhov kev them nqi hluav taws xob tsis muaj qhov cuam tshuam rau lub roj teeb tsis ua haujlwm, qhov qis qis lossis siab dhau ntawm qhov kev them nqi hluav taws xob yuav ua rau qhov cuam tshuam cuam tshuam ntawm LiFePO4 electrode: qis qis. txwv voltage yuav tsis ua haujlwm zoo. Cov zaj duab xis passivation yog tsim nyob rau hauv av, thiab ib tug dhau-high voltage txwv yuav ua rau cov oxidative decomposition ntawm cov electrolyte. Nws yuav tsim ib yam khoom uas tsis tshua muaj conductivity nyob rau saum npoo ntawm LiFePO4 electrode.

Lub peev xwm tawm ntawm LiFePO4 lub zog hluav taws xob roj teeb yuav poob sai sai thaum qhov kub thiab txias, feem ntau yog vim qhov txo qis ntawm ion conductivity thiab qhov nce ntawm qhov cuam tshuam cuam tshuam. Li tau kawm LiFePO4 cathode thiab graphite anode cais thiab pom tias lub ntsiab tswj cov yam ntxwv uas txwv qhov kub-kub kev ua haujlwm ntawm anode thiab anode sib txawv. Qhov txo qis hauv ionic conductivity ntawm LiFePO4 cathode yog qhov tseem ceeb, thiab qhov nce hauv qhov cuam tshuam cuam tshuam ntawm graphite anode yog qhov laj thawj tseem ceeb.

Thaum siv, qhov degradation ntawm LiFePO4 electrode thiab graphite anode thiab kev loj hlob tsis tu ncua ntawm SEI zaj duab xis yuav ua rau lub roj teeb tsis ua hauj lwm sib txawv. Tsis tas li ntawd, ntxiv rau cov yam ntxwv uas tsis tuaj yeem tswj tau xws li cov xwm txheej hauv txoj kev thiab qhov kub thiab txias, kev siv lub roj teeb tsis tu ncua yog qhov tseem ceeb, suav nrog qhov tsim nyog them hluav taws xob, qhov tsim nyog qhov tob ntawm kev tawm, thiab lwm yam.

4. tsis ua hauj lwm thaum lub sij hawm them thiab tso tawm

Lub roj teeb feem ntau inevitably overcharged thaum siv. Muaj tsawg tshaj tawm. Lub tshav kub tso tawm thaum lub sij hawm overcharge los yog over-discharge yog feem ntau yuav tsub kom nyob rau hauv lub roj teeb, ntxiv rau lub roj teeb kub. Nws cuam tshuam rau lub roj teeb lub neej kev pab cuam thiab ua rau muaj hluav taws kub los yog tawg ntawm cua daj cua dub. Txawm tias nyob rau hauv kev them nyiaj thiab tso tawm tsis tu ncua, raws li tus lej ntawm lub voj voog nce, lub peev xwm tsis sib xws ntawm tib lub hlwb hauv lub roj teeb yuav nce ntxiv. Lub roj teeb uas muaj peev xwm qis tshaj plaws yuav dhau los ua cov txheej txheem ntawm kev them nqi thiab tshaj tawm tawm.

Txawm hais tias LiFePO4 muaj qhov zoo tshaj plaws thermal stability piv rau lwm cov khoom siv hluav taws xob zoo nyob rau hauv cov xwm txheej sib txawv, kev them nyiaj ntau dhau tuaj yeem ua rau muaj kev pheej hmoo tsis zoo hauv kev siv roj teeb LiFePO4. Nyob rau hauv lub xeev overcharged, cov kuab tshuaj nyob rau hauv cov organic electrolyte yog ntau oxidative decomposition. Ntawm cov feem ntau siv cov kuab tshuaj organic, ethylene carbonate (EC) yuav nyiam mus rau oxidative Decomposition ntawm qhov zoo electrode. Txij li thaum lub lithium insertion muaj peev xwm (piv rau lithium muaj peev xwm) ntawm qhov tsis zoo graphite electrode yog ntiav, lithium nag lossis daus yog qhov muaj feem cuam tshuam rau qhov tsis zoo graphite electrode.

Ib qho ntawm cov laj thawj tseem ceeb rau lub roj teeb tsis ua haujlwm nyob rau hauv cov xwm txheej overcharged yog qhov luv luv Circuit Court tshwm sim los ntawm lithium siv lead ua ceg tho lub diaphragm. Lu et al. soj ntsuam qhov tsis ua hauj lwm mechanism ntawm lithium plating ntawm graphite opposing electrode nto tshwm sim los ntawm overcharge. Cov txiaj ntsig tau pom tias tag nrho cov qauv ntawm qhov tsis zoo graphite electrode tsis tau hloov pauv, tab sis muaj lithium siv lead ua cov ceg ntoo thiab zaj duab xis nto. Cov tshuaj tiv thaiv ntawm lithium thiab electrolyte ua rau cov zaj duab xis saum npoo nce ntxiv, uas siv lithium ntau dua thiab ua rau lithium diffuse rau hauv graphite. Qhov tsis zoo electrode ua ntau nyuaj, uas yuav ntxiv dag zog rau lithium deposition nyob rau saum npoo ntawm qhov tsis zoo electrode, uas ua rau ib tug ntxiv txo nyob rau hauv lub peev xwm thiab coulombic efficiency.

Tsis tas li ntawd, hlau impurities (tshwj xeeb tshaj yog Fe) feem ntau suav hais tias yog ib qho ntawm cov laj thawj tseem ceeb rau roj teeb overcharge tsis ua hauj lwm. Xu et al. systematically kawm qhov tsis ua hauj lwm mechanism ntawm LiFePO4 fais fab roj teeb nyob rau hauv overcharge tej yam kev mob. Cov txiaj ntsig tau pom tias qhov redox ntawm Fe thaum lub sij hawm dhau los / tawm lub voj voog yog qhov ua tau, thiab cov tshuaj tiv thaiv tau muab. Thaum overcharge tshwm sim, Fe yog thawj oxidized rau Fe2 +, Fe2 + ntxiv deteriorates rau Fe3 +, thiab ces Fe2 + thiab Fe3 + raug tshem tawm ntawm lub zoo electrode. Ib sab diffuses rau sab tsis zoo electrode, Fe3+ thaum kawg txo rau Fe2+, thiab Fe2+ yog ntxiv txo rau daim ntawv Fe; Thaum lub sij hawm dhau los / tawm mus, Fe siv lead ua cov ceg ntoo yuav pib ntawm qhov zoo thiab qhov tsis zoo ntawm electrodes tib lub sijhawm, tho qhov sib cais los tsim Fe txuas hniav, ua rau cov roj teeb me me luv luv, qhov tshwm sim tshwm sim uas nrog lub roj teeb lub micro luv luv Circuit Court yog qhov txuas ntxiv. nce kub tom qab overcharge.

Thaum overcharge, lub peev xwm ntawm qhov tsis zoo electrode yuav nce sai. Qhov muaj peev xwm nce ntxiv yuav rhuav tshem SEI zaj duab xis nyob rau saum npoo ntawm qhov tsis zoo electrode (ib feem nplua nuj nyob rau hauv inorganic compounds nyob rau hauv SEI zaj duab xis yog feem ntau yuav oxidized), uas yuav ua rau ntxiv decomposition ntawm cov electrolyte, uas ua rau poob ntawm lub peev xwm. Qhov tseem ceeb tshaj, cov khoom tsis zoo tam sim no Cu ntawv ci yuav raug oxidized. Hauv SEI zaj duab xis ntawm qhov tsis zoo electrode, Yang li al. kuaj pom Cu2O, cov khoom oxidation ntawm Cu foil, uas yuav ua rau kom lub roj teeb lub zog sab hauv thiab ua rau lub peev xwm poob ntawm cua daj cua dub.

Nws et al. tau kawm txog cov txheej txheem tshaj tawm ntawm LiFePO4 cov roj teeb fais fab kom ntxaws. Cov txiaj ntsig tau pom tias cov khoom tsis zoo tam sim no Cu ntawv ci tuaj yeem oxidized rau Cu + thaum tshaj tawm, thiab Cu + yog ntxiv oxidized rau Cu2 +, tom qab ntawd lawv diffuse mus rau qhov zoo electrode. Kev txo cov tshuaj tiv thaiv tuaj yeem tshwm sim ntawm qhov zoo electrode. Nyob rau hauv txoj kev no, nws yuav tsim cov ceg ntoo siv lead ua nyob rau sab zoo electrode, tho qhov sib cais thiab ua rau lub voj voog luv luv hauv lub roj teeb. Tsis tas li ntawd, vim kev tso tawm ntau dhau, lub roj teeb kub yuav nce ntxiv.

Overcharge ntawm LiFePO4 fais fab roj teeb yuav ua rau oxidative electrolyte decomposition, lithium evolution, thiab tsim Fe siv lead ua ceg; Tshaj tawm tuaj yeem ua rau SEI puas tsuaj, ua rau muaj peev xwm degradation, Cu foil oxidation, thiab txawm zoo li Cu siv lead ua ceg.

5. lwm yam ua tsis tiav

Vim yog qhov tsis tshua muaj conductivity ntawm LiFePO4, morphology thiab qhov loj ntawm cov khoom nws tus kheej thiab cov teebmeem ntawm cov khoom siv hluav taws xob thiab cov ntawv khi tau yooj yim tshwm sim. Gaberscek thiab al. tau tham txog ob qhov tsis sib xws ntawm qhov loj me thiab cov txheej txheem carbon thiab pom tias cov electrode impedance ntawm LiFePO4 tsuas yog cuam tshuam rau qhov nruab nrab particle loj. Kev tiv thaiv qhov chaw tsis xws luag hauv LiFePO4 (Fe nyob hauv Li qhov chaw) yuav muaj kev cuam tshuam tshwj xeeb rau kev ua haujlwm ntawm lub roj teeb: vim tias kev sib kis ntawm lithium ions hauv LiFePO4 yog ib qho, qhov tsis zoo no yuav cuam tshuam kev sib txuas lus ntawm lithium ions; vim qhov kev taw qhia ntawm high valence xeev Vim yog qhov ntxiv electrostatic repulsion, qhov tsis xws luag kuj tuaj yeem ua rau qhov tsis ruaj khov ntawm LiFePO4 qauv.

Cov khoom loj ntawm LiFePO4 tsis tuaj yeem txaus siab rau qhov kawg ntawm kev them nyiaj; nano-structured LiFePO4 tuaj yeem txo qhov kev hloov pauv tsis xws luag, tab sis nws lub zog siab saum npoo yuav ua rau nws tus kheej tawm. PVDF yog cov khoom siv feem ntau siv tam sim no, uas muaj qhov tsis zoo xws li cov tshuaj tiv thaiv ntawm qhov kub thiab txias, kev sib cais hauv cov dej tsis muaj dej, thiab tsis muaj zog txaus. Nws muaj kev cuam tshuam tshwj xeeb rau lub peev xwm poob thiab lub neej voj voog ntawm LiFePO4. Tsis tas li ntawd, cov khoom siv tam sim no, diaphragm, electrolyte muaj pes tsawg leeg, cov txheej txheem tsim khoom, tib neeg cov yam ntxwv, kev co sab nraud, kev poob siab, thiab lwm yam, yuav cuam tshuam rau lub roj teeb kev ua tau zoo rau ntau qib.

Reference: Miao Meng et al. "Kev Tshawb Fawb Txog Kev Ua Haujlwm ntawm Lithium Iron Phosphate Fais Fab Kev Ua Haujlwm."