◆Dab tsi yog aqueous electrolytes?
◆Taw qhia rau Khoom Electrolytes
Cov electrolyte, ib qho tseem ceeb ntawm cov khoomlithium{0}} ion roj teeb, ua lub luag haujlwm tseem ceeb hauv lub roj teeb lub zog - tawm mus.
Nws tsis yog tsuas yog lub luag haujlwm rau kev thauj mus los ntawm lithium ions thiab kev ua haujlwm ntawm tam sim no, tab sis kuj muaj cov khoom siv hluav taws xob hluav taws xob los tiv thaiv cov hluav taws xob ncaj qha ntawm qhov zoo thiab tsis zoo electrodes. Figuratively hais lus, cov electrolyte zoo li "ntshav" hauv lithium- ion roj teeb, ua kom muaj kev sib txuas ntawm cov khoom siv hluav taws xob zoo thiab tsis zoo, yog li lav qhov kev vam meej ntawm tag nrho cov nqi - paug.
Ib qho zoo tagnrho electrolyte rau lithium -ion roj teeb yuav tsum ua tau raws li tsib yam hauv qab no:
(1) High ionic conductivity (>10⁻3S / cm).
(2) Wide electrochemical window (>4.5 V V Li+/Li).
(3) Kev sib raug zoo nrog cov electrodes, tswj qhov qis tshaj qhov ua tau ntawm kev sib tshuam.
(4) Cov thermal thiab tshuaj lom neeg ruaj khov zoo heev, ua rau lub roj teeb ua haujlwm zoo tshaj qhov kub thiab txias.
(5) Tus nqi qis, tsis muaj tshuaj lom, thiab ib puag ncig zoo.
Nrog rau qhov puas tau -kev xav tau ntau ntxiv rau roj teeb lub zog ceev thiab lub zog ceev, roj teeb thev naus laus zis tau txhim kho sai, thiab cov khoom siv hluav taws xob tau ua tiav zoo heev. Nyob rau hauv sib piv, txoj kev loj hlob ntawm electrolyte systems tau lagged qab. Tam sim no, txoj kev loj hlob ntawm lithium- ion roj teeb electrolytes tuaj yeem muab faib ua peb hom: non-aqueous solvent electrolytes, aqueous electrolytes, thiab solid-state electrolytes.
Tsis yog -aqueous solvent electrolyte
Tsis yog -aqueous kuab electrolytes nyob rau hauv lithium{1}} ion roj teeb hais txog cov tshuab electrolyte uas tsis muaj dej, feem ntau muaj cov kuab tshuaj, cov kuab tshuaj (feem ntau yog lithium ntsev), thiab cov khoom ntxiv. Cov no tsis yog - cov kuab tshuaj aqueous feem ntau yog cov kuab tshuaj organic, tsis yog cov kuab tshuaj aqueous, kom tsis txhob muaj cov dej electrolysis los yog cov tshuaj tsis zoo nrog cov khoom siv electrode. Lithium ntsev yog cov khoom tseem ceeb rau kev thauj khoom lithium-ion thauj, cov kuab tshuaj ua haujlwm raws li kev sib cais, kev sib cais, thiab kev txhawb nqa rau lithium ntsev, thiab cov khoom ntxiv ua haujlwm feem ntau los txhim kho cov khoom siv hluav taws xob lossis kev nyab xeeb ntawm lithium- ion roj teeb.
Cov khoom lag luam muaj electrolytes (piv txwv li, kua electrolytes) siv hauv lithium- ion roj teeb feem ntau yog tsim los ntawm ib lossis ntau dua lithium ntsev yaj hauv ob lossis ntau dua cov kuab tshuaj organic; electrolytes tsim los ntawm ib qho hnyav hnyav yog tsawg heev. Qhov laj thawj ntawm kev siv ntau cov kuab tshuaj yog qhov tiag - cov roj teeb hauv ntiaj teb muaj qhov sib txawv, txawm tias qhov tsis sib xws, cov kev cai uas nyuaj rau kev siv ib qho hnyav. Piv txwv li, electrolytes yuav xav tau fluidity siab thaum tseem muaj lub siab dielectric tas li; Yog li ntawd, cov kuab tshuaj nrog cov khoom sib txawv physicochemical feem ntau siv ua ke, nthuav tawm cov yam ntxwv sib txawv ib txhij. Tsis tas li ntawd, lithium ntsev feem ntau tsis siv tib lub sijhawm vim tias kev xaiv cov roj lithium ntsev tsawg, thiab lawv qhov zoo tsis yooj yim pom.
Qhov zoo tshaj plaws organic solvents yuav tsum muaj cov yam ntxwv tseem ceeb hauv qab no: Ua ntej, lawv xav tau lub siab dielectric tas li kom ntseeg tau tias muaj kev sib cais zoo ntawm lithium ntsev; thib ob, lawv yuav tsum muaj qhov tsis tshua muaj melting point thiab kub kub taw tes kom nthuav dav cov kev khiav hauj lwm kub ntawm cov electrolyte; thib peb, tsawg viscosity pab txhawb kev tsiv teb tsaws ntawm lithium ions hauv nruab nrab; thiab thaum kawg, cov kuab tshuaj no yuav tsum pheej yig thiab muaj toxicity tsawg (tseem ceeb tsis yog - lom). Carbonate tebchaw, raws li ib tug ntawm cov ntxov tshaj plaws thiab feem ntau lug siv organic solvents nyob rau hauv lub lithium{2}} ion roj teeb kev lag luam, nyob rau hauv ib tug tseem ceeb txoj hauj lwm nyob rau hauv lub teb ntawm roj teeb electrolytes.
Tam sim no, hom hnyav no feem ntau suav nrog ob hom qauv: cyclic thiab saw. Cov lus hauv qab no piav qhia txog qhov cuam tshuam ntawm lub cev ntawm ob peb feem ntau siv tsis yog -aqueous solvents, electrolytes, thiab organic solvents.
| Qeb | Hom | Qauv | Melting Point (zeeg) | Kub Point (degree) | Tus kheej Vapor Siab (25 degree) | Relative Density (25 degree) / (mPa·s) |
|---|---|---|---|---|---|---|
| Ethylene Carbonate (EC) | Cyclic | 36.4 | 248 | 89,780 | 1.904 (40 degree) | |
| Propylene Carbonate (PC) | Cyclic | -48.4 | 242 | 64,920 | 2.53 | |
| Carbonates | Butylene Carbonate (BC) | Cyclic | -54.0 | 240 | 53,000 | 3.20 |
| Dimethyl Carbonate (DMC) | Tawm | 4.6 | 91 | 3,107 | 0.59 | |
| Diethyl Carbonate (DEC) | Tawm | -74.3 | 126 | 2,805 | 0.75 | |
| Ethyl Methyl Carbonate (EMC) | Tawm | -53.0 | 110 | 2,958 | 0.65 |
Tam sim no, cov kuab tshuaj alkyl carbonate tau siv dav hauv electrolytes. Cov kuab tshuaj no muaj oxidation zoo thiab muaj kev ruaj ntseg zoo nyob rau hauv high voltage tej yam kev mob. Cyclic carbonates, xws li ethylene carbonate thiab propylene carbonate, paub txog lawv cov dielectric siab tas li, txhais tau tias lawv tuaj yeem yaj lithium ntsev zoo dua; Txawm li cas los xij, vim muaj zog intermolecular rog, cov kuab tshuaj no muaj viscosity siab, uas ua rau qeeb zog ntawm lithium ions hauv lawv. Nyob rau hauv sib piv, saw carbonates, xws li dimethyl carbonate thiab diethyl carbonate, thaum muaj qis viscosity, kuj muaj cov dielectric tsis tu ncua, uas ua rau cov dissolution tsis zoo rau lithium ntsev. Yog li ntawd, txhawm rau npaj cov kev daws teeb meem nrog kev ua tau zoo ionic conductivity, ntau hom kuab tshuaj feem ntau sib xyaw, xws li PC + DEC lossis EC + DMC kev sib txuas. Lithium ntsev, raws li lub hauv paus ntawm lithium ions hauv electrolyte, ua lub luag haujlwm tseem ceeb hauv lithium- ion ion thauj thaum lub sijhawm them thiab tso tawm ntawm lithium - ion roj teeb. Their performance directly affects many aspects of lithium-ion batteries, including energy density, power density, operating voltage range, cycle life, and safety. Tam sim no, nyob rau hauv kev tshawb fawb thiab kev lag luam xyaum, lithium ntsev nrog loj anionic radii thiab siab redox stability feem ntau yog xaiv. Raws li lawv cov tshuaj muaj pes tsawg leeg, lithium ntsev tuaj yeem muab faib ua ob pawg: inorganic lithium ntsev thiab organic lithium ntsev. Ntau cov ntsev lithium inorganic tau tsim, suav nrog LiPF6, LiClO4, LIBF, thiab LIASF. Nyob rau hauv sib piv, feem ntau siv organic lithium ntsev nyob rau hauv lithium{17}} ion roj teeb yog tsim los ntawm kev ntxiv electron - rho pab pawg mus rau cov anions ntawm cov inorganic lithium ntsev, xws li lithium dioxalato -borate (LiBOB), lithium difluorooxalatoborate{20} difluorosulfonylimide (LiFSI), thiab lithium ditrifluoromethylsulfonylimide (LTFSI). Cov lus hauv qab no qhia txog cov khoom siv hluav taws xob muaj feem cuam tshuam ntawm ntau cov roj ntsha lithium uas nquag siv hauv lithium - ion roj teeb.
| Qeb | Lithium ntsev | Molecular Luj (g / mol) | Soluble hauv Carbonates? | Soluble hauv dej? | Hluav taws xob conductivity (1 mol / L, EC / DMC, 20 degree) (mS / cm) |
|---|---|---|---|---|---|
| Inorganic Lithium ntsev | LiPF ₆ | 151.91 | Yog lawm | Yog lawm | 10.00 |
| LiBF ₄ | 93.74 | Yog lawm | Yog lawm | 4.50 | |
| LiClO₄ | 106.40 | Yog lawm | Yog lawm | 9.00 | |
| Organic Lithium ntsev | LiTFSI | 287.08 | Yog lawm | Yog lawm | 6.18 |
| LiFSI | 187.07 | Yog lawm | Yog lawm | 10.40 | |
| LiBOB | 193.79 | Yog lawm | Yog lawm | 0.65 |
Cov khoom siv ntxiv yog cov khoom ntxiv rau cov electrolyte hauv qhov tsis tshua muaj siab (feem ntau tsis pub ntau tshaj 10% los ntawm huab hwm coj) uas muaj cov haujlwm tshwj xeeb thiab tuaj yeem txhim kho cov yam ntxwv electrochemical ntawm lub roj teeb. Raws li lawv txoj haujlwm, cov khoom siv ntxiv no tuaj yeem muab faib ua ntau pawg: zaj duab xis- tsim cov khoom siv ntxiv, cov nplaim hluav taws xob, thiab cov khoom siv ntxiv los tiv thaiv overcharging. Tsis tas li ntawd, muaj cov additives siv los txhim kho conductivity, optimize kev ua tau zoo nyob rau hauv qis - kub tej yam kev mob, los yog tswj tus nqi thiab HF concentrations nyob rau hauv cov tshuaj electrolyte.