◆Li-electrolyte tse nang le metsi ke eng?
◆Selelekela ho Solid Electrolytes
Electrolyte, karolo ea bohlokoa ealithium{0}}libetri tsa ion, e bapala karolo ea bohlokoa ho tjhajang ha betri-nakong ya ho ntsha betri.
Ha e ikarabelle feela bakeng sa ho tsamaisa li-ion tsa lithium le ho tsamaisoa ha hona joale, empa hape e na le thepa ea ho kenya lisebelisoa tsa elektronike ho thibela ka katleho phallo e tobileng ea elektronike pakeng tsa li-electrode tse ntle le tse mpe. Ka puo ea tšoantšetso, electrolyte e tšoana le "mali" ka har'a betri ea lithium-ion, e netefatsang khokahanyo lipakeng tsa lisebelisoa tsa elektrode tse ntle le tse mpe, kahoo e netefatsa tsoelo-pele e ntle ea ho tjhaja{2}}mokhoa oa ho ntša motlakase.
Electrolyte e loketseng bakeng sa betri ea lithium{0}}ion e tlameha ho fihlela litlhoko tse latelang tse hlano:
(1) High ionic conductivity (>10⁻3S/cm).
(2) Wide electrochemical window (>4.5 V vs. Li+/Li).
(3) Ho lumellana hantle le li-electrode, ho boloka khanyetso e tlase ka ho fetisisa ea sefahleho.
(4) Botsitso bo botle ba mocheso le lik'hemik'hale, bo nolofalletsang betri ho sebetsa ka mokhoa o sireletsehileng holim'a mocheso o pharaletseng.
(5) Theko e tlase, chefo e tlase, le tikoloho.
Ka litlhoko tse ntseng li eketseha- tsa matla a betri le matla a matla, theknoloji ea betri e ntse e tsoela pele ka potlako, 'me lisebelisoa tsa li-electrode li hatetse pele haholo. Ka lehlakoreng le leng, nts'etsopele ea litsamaiso tsa electrolyte e salletse morao. Hajoale, nts'etsopele ea li-electrolyte tsa betri tsa lithium-ion li ka aroloa ka mefuta e meraro: -li-electrolyte tse qhibilihang ka metsi, li-electrolyte tse nang le metsi, le{5}}li-electrolyte tse tiileng.
Electrolyte e seng-ea aqueous solvent
Li-electrolyte tseo e seng-li-aqueous solvent electrolyte ka har'a libetri tsa lithium-ion li bua ka lisebelisoa tsa electrolyte tse se nang metsi, haholo-holo tse entsoeng ka metsoako, solutes (hangata ke matsoai a lithium), le metsoako. Litlhapi tsena tseo e seng- tse nang le metsi hangata ke lihlapolli tsa tlhaho, ho e-na le lihlapolli tse nang le metsi, ho qoba electrolysis ea metsi kapa liphetoho tse mpe ka lisebelisoa tsa electrode. Matsoai a lithium ke tsona tse tsamaisang lithium-lipalangoang tsa ion, lihlapolli li sebetsa e le ho qhala, ho hasa, le ho tšehetsa matsoai a lithium, 'me li-additives li sebetsa ho ntlafatsa tšebetso ea electrochemical kapa polokeho ea libeteri tsa lithium{6}}.
Li-electrolyte tse fumanehang khoebong (ke hore, li-electrolyte tse metsi) tse sebelisoang ka har'a lithium-libetri tsa ion li entsoe haholo-holo ka letsoai la lithium le le leng kapa a mangata a qhibilihang ka har'a lihlapolli tse peli kapa ho feta; li-electrolyte tse entsoeng ka motsoako o le mong li fumaneha seoelo haholo. Lebaka la ho sebedisa tse hlapollang tse ngata ke hore- dibetri tsa nnete tsa lefatshe di na le ditlhoko tse fapaneng, esita le tse hanyetsanang, tseo ho leng thata ho di fihlela ha o sebedisa sehlapi se le seng. Ka mohlala, li-electrolyte li ka 'na tsa hloka metsi a mangata ha li ntse li e-na le boemo bo phahameng ba dielectric; ka hona, li-solvents tse nang le lisebelisoa tse fapaneng tsa physicochemical li atisa ho sebelisoa hammoho, li bonts'a litšobotsi tse fapaneng ka nako e le 'ngoe. Ho feta moo, letsoai la lithium ka kakaretso ha le sebelisoe ka nako e le 'ngoe hobane khetho ea letsoai la lithium e lekanyelitsoe,' me melemo ea bona ha e bonahale habonolo.
Li-solvents tse loketseng tsa manyolo li lokela ho ba le lisebelisoa tse latelang tsa bohlokoa: Taba ea pele, li hloka "dielectric constant" e phahameng ho netefatsa hore letsoai la lithium le qhibiliha hantle; ea bobeli, ba lokela ho ba le ntlha e tlaase ea ho qhibiliha le ntlha e phahameng ea ho bela ho atolosa mocheso oa ho sebetsa oa electrolyte; ea boraro, viscosity e tlase e thusa ho khothaletsa ho falla ha lithium ion bohareng; 'me qetellong, lihlapolli tsena li tlameha ho ba theko e tlase 'me li be le chefo e tlase (ha e le hantle e se{0}} chefo). Metsoako ea carbonate, e le e 'ngoe ea lihlapolli tsa pele-pele tse sebelisoang haholo indastering ea betri ea lithium-, li boemong ba bohlokoa haholo lefapheng la li-electrolyte tsa betri.
Hajoale, mofuta ona oa solvent haholo-holo o kenyelletsa mefuta e 'meli ea meralo: cyclic le ketane. Tafole e ka tlase e akaretsa lintlha tse amehang tsa -li-aqueous solvents, electrolyte, le organic solvents tse sebelisoang hangata.
| Sehlopha | Mofuta | Sebopeho | Melting Point (℃) | Boiling Point (℃) | Khatello ea Mouoane ka Mong (25 degrees) | Boima ba Kamano (25 degrees)/(mPa·s) |
|---|---|---|---|---|---|---|
| Ethylene carbonate (EC) | cyclic | 36.4 | 248 | 89,780 | 1.904 (40 likhato) | |
| Propylene carbonate (PC) | cyclic | -48.4 | 242 | 64,920 | 2.53 | |
| Likhabonete | Butylene carbonate (BC) | cyclic | -54.0 | 240 | 53,000 | 3.20 |
| Dimethyl carbonate (DMC) | Linear | 4.6 | 91 | 3,107 | 0.59 | |
| Diethyl carbonate (DEC) | Linear | -74.3 | 126 | 2,805 | 0.75 | |
| Ethyl Methyl Carbonate (EMC) | Linear | -53.0 | 110 | 2,958 | 0.65 |
Hajoale, li-solvents tsa alkyl carbonate li sebelisoa haholo ho li-electrolyte. Li-solvents tsena li na le khanyetso e ntle ea oxidation mme li bonts'a botsitso bo botle tlasa maemo a phahameng a motlakase. Li-cyclic carbonates, tse kang ethylene carbonate le propylene carbonate, li tsejoa ka maemo a tsona a phahameng a dielectric, ho bolelang hore li ka qhaqha letsoai la lithium ka katleho; leha ho le joalo, ka lebaka la matla a matla a li-intermolecular, li-solvents tsena li na le viscosity e phahameng, e fokotsang ho tsamaea ha li-ion tsa lithium ka hare ho tsona. Ka lehlakoreng le leng, chain carbonates, joalo ka dimethyl carbonate le diethyl carbonate, ha e ntse e e-na le viscosity e tlase, le eona e na le li-contants tse fokolang tsa dielectric, e leng se bakang ts'ebetso e mpe ea ho qhibiliha ha letsoai la lithium. Ka hona, ho lokisa litsamaiso tsa tharollo ka conductivity e phahameng ea ionic, mefuta e fapaneng ea li-solvents hangata e tsoakoa, joalo ka metsoako ea PC + DEC kapa EC + DMC. Matsoai a lithium, joalo ka mohloli oa li-ion tsa lithium ka har'a electrolyte, a bapala karolo e kholo ho lipalangoang tsa li-ion tsa lithium-nakong ea ho tjhaja le ho ntša libeteri tsa lithium{8}}ion. Ts'ebetso ea bona e ama ka kotloloho likarolo tse ngata tsa libeteri tsa lithium{10}}ion, ho kenyeletsoa ho teteana ha matla, ho teteana ha motlakase, mefuta ea motlakase ea ho sebetsa, nako ea potoloho le polokeho. Hajoale, lipatlisisong tsa laboratori le ts'ebetsong ea indasteri, matsoai a lithium a nang le radii e kholo ea anionic le botsitso bo phahameng ba redox hangata a khethoa. Ho ipapisitsoe le sebopeho sa bona sa lik'hemik'hale, letsoai la lithium le ka aroloa ka mekhahlelo e 'meli: matsoai a inorganic lithium le letsoai la organic lithium. Ho entsoe matsoai a mangata a inorganic lithium, ho kenyeletsoa LiPF6, LiClO4, LIBF, le LIASF. Ka lehlakoreng le leng, matsoai a lithium a sebelisoang hangata a lithium-libetri tsa ion a etsoa ka ho kenya li-electron{18}}lihlopha tsa ho ntša li-anion tsa matsoai ana a inorganic lithium, joalo ka lithium dioxalato-borate (LiBOB), lithium difluorooxalato{{20}DFBrolimide lithium difluode] (LiFSI), le lithium ditrifluoromethylsulfonylimide (LTFSI).Lethathamo le ka tlase le bontša likarolo tse amehang tsa physicochemical tsa matsoai a mangata a sebelisoang hangata ka har'a libeteri tsa lithium{22}}.
| Sehlopha | Letsoai la lithium | Boima ba Molek'hule (g/mol) | E qhibiliha ka carbonates? | E qhibilihang ka Metsing? | Tsamaiso ea Motlakase (1 mol/L, EC/DMC, 20℃) (mS/cm) |
|---|---|---|---|---|---|
| Inorganic Lithium Letsoai | LiPF₆ | 151.91 | Ee | Ee | 10.00 |
| LiBF₄ | 93.74 | Ee | Ee | 4.50 | |
| LiClO₄ | 106.40 | Ee | Ee | 9.00 | |
| Matsoai a Organic Lithium | LiTFSI | 287.08 | Ee | Ee | 6.18 |
| LiFSI | 187.07 | Ee | Ee | 10.40 | |
| LiBOB | 193.79 | Ee | Ee | 0.65 |
Li-additives ke lintho tse kenyellelitsoeng ho electrolyte maemong a tlase (hangata ha li fete 10% ka boima) tse nang le mesebetsi e itseng 'me li ka ntlafatsa haholo litšobotsi tsa electrochemical tsa betri. Ho ipapisitsoe le mesebetsi ea bona, li-additives li ka aroloa ka mekhahlelo e mengata: filimi{2}}e etsa li-additives, li-flame retardants, le li-additives ho thibela ho tjhaja ho feta tekano. Ho feta moo, ho na le litlatsetso tse sebelisetsoang ho ntlafatsa tšebetso, ho ntlafatsa ts'ebetso ka tlas'a{4}}maemo a mocheso a tlase, kapa ho laola palo le likhakanyo tsa HF mothapong oa electrolyte.