◆Wanem samting em ol 'aqueous electrolytes'?
◆Tok i go pas long ol strongpela 'electrolytes'
Electrolyte, em i wanpela bikpela samting bilonglithium-ion bateri, i save mekim bikpela wok long taim bilong 'charge-discharge bilong bateri.
Em i no inap long karim gut ol 'lithium ions' na 'conduction' bilong 'current' tasol, em i gat ol 'electronic insulation' samting tu long pasim ol 'electron' long ron namel long ol 'positive' na 'negative' 'electrodes'. Long tok piksa, 'electrolyte' i olsem "blut" insait long wanpela 'lithium-ion' bateri, na i save mekim wok namel long ol 'positive' na 'negative' 'electrode' samting i pas gut wantaim, na dispela i save mekim wok bilong 'charge-discharge i ron gut.
Wanpela gutpela 'electrolyte' bilong wanpela 'lithium-ion' bateri i mas inapim ol dispela 5-pela samting:
(1) High ionic conductivity (>10⁻3S/cm).
(2) Wide electrochemical window (>4.5 V egensim Li+/Li).
(3) Gutpela wok wantaim ol 'electrodes', na holim liklik 'interfacial resistance'.
(4) Gutpela 'thermal' na 'chemical stability', na dispela i mekim na bateri i ken wok gut long kain kain tempereja.
(5) I no gat bikpela pe, i no gat planti marasin nogut long en, na i no bagarapim envairomen.
Wantaim ol askim we i wok long kamap bikpela long 'battery energy density' na 'power density', 'battery technology' i wok long kamap hariap tru, na ol samting bilong wokim ol 'electrode' i kamap gutpela tru. Tasol, wok bilong kamapim ol 'electrolyte' sistem i stap bihain. Nau yet, wok bilong kamapim ol 'lithium-ion battery electrolytes' i ken bruk i go long tripela kain: ol non-aqueous solvent electrolytes, ol aqueous electrolytes, na ol solid-state electrolytes.
Non-aqueous solvent electrolyte
Ol 'non-aqueous solvent electrolytes insait long ol 'lithium-ion' bateri i makim ol 'electrolyte' sistem we i no gat wara, we planti bilong ol i gat ol 'solvents', 'solutes' (planti taim ol 'lithium salts'), na ol 'additives'. Ol dispela 'non-aqueous solvents em ol i save kamap olsem ol 'organic solvents', na i no ol 'aqueous solvents', bilong abrusim 'electrolysis' bilong wara o ol hevi we i kamap wantaim ol samting bilong 'electrode'. Ol sol bilong 'lithium' em ol nambawan samting bilong karim 'lithium-ion', ol 'solvent' i save wok olsem 'dissolution', 'dispersion', na sapot bilong 'lithium salts', na ol 'additives' i save wok long helpim ol 'electrochemical performance' o sefti bilong ol 'lithium{6}}ion' bateri.
Ol 'electrolytes' we ol i save salim long stua (olsem, 'liquid electrolytes') we ol i save yusim long ol 'lithium-ion' bateri em ol i save wokim long wanpela o moa 'lithium salts' we i tanim insait long tupela o moa 'organic solvents'; ol 'electrolytes' we i gat wanpela 'solvent' tasol i no save kamap planti. As bilong yusim planti 'solvent' em olsem ol 'real-bateri bilong wol i gat ol narapela narapela, na i no wankain, ol samting we i hat long inapim sapos yu yusim wanpela 'solvent' tasol. Olsem, ol 'electrolytes' i nidim bikpela 'fluidity' na tu i gat bikpela 'dielectric constant'; olsem na, ol i save yusim ol 'solvent' wantaim ol narapela narapela 'physicochemical properties' wantaim, na ol i save soim ol narapela narapela pasin wantaim. Na tu, ol i no save yusim ol 'lithium salts' wantaim bikos ol i no save makim planti 'lithium salts', na ol gutpela samting bilong ol i no isi long luksave long en.
Ol gutpela 'organic solvents' i mas gat ol dispela bikpela samting: Namba wan, ol i mas i gat bikpela 'dielectric constant' bilong mekim ol 'lithium salts' i kapsait gut; namba tu, ol i mas gat liklik melting poin na bikpela boiling poin long mekim 'operating temperature range' bilong 'electrolyte' i go bikpela; namba tri, liklik 'viscosity' i helpim long promotim gutpela 'migration' bilong ol 'lithium ions' insait long 'medium'; na laspela, ol dispela solvent i no gat bikpela pe na i no gat planti posin (gutpela sapos i no gat -toksik). Ol 'carbonate compounds', olsem wanpela bilong ol namba wan na planti 'organic solvents' we ol i save yusim insait long 'lithium-ion' bateri indastri, i gat bikpela wok insait long 'field' bilong ol 'battery electrolytes'.
Nau yet, dispela kain solvent i gat tupela kain: 'cyclic' na 'chain'. Tebol aninit i soim ol 'physical parameters' bilong sampela 'non-aqueous solvents', 'electrolytes', na 'organic solvents' we ol i save yusim planti taim.
| Kategori | Taip | Straksa | Melting Point (digri) | Boiling Point (digri) | Presa bilong wanwan steam (25 digri) | Relative Density (25℃)/(mPa·s) |
|---|---|---|---|---|---|---|
| Ethylene Carbonate (EC) | Saiklik | 36.4 | 248 | 89,780 | 1.904 (40 digri) | |
| Propylene Carbonate (PC) | Saiklik | -48.4 | 242 | 64,920 | 2.53 | |
| Kabonet | Butylene Carbonate (BC) | Saiklik | -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 |
Nau yet, ol i save yusim planti 'alkyl carbonate solvents' insait long ol 'electrolytes'. Ol dispela 'solvent' i gat gutpela 'oxidation resistance' na i soim gutpela 'stability' aninit long ol 'high voltage' kondisen. Ol 'cyclic carbonatees', olsem 'ethylene carbonate' na 'propylene carbonate', ol i save long ol i gat bikpela 'dielectric constants', na dispela i min olsem ol inap long rausim ol 'lithium salts' gut moa; tasol, bikos long strongpela 'intermolecular forces', ol dispela 'solvent' i gat bikpela 'viscosity', we i save daunim muvmen bilong ol 'lithium ions' insait long ol. Tasol, ol 'chain carbonate', olsem 'dimethyl carbonate' na 'diethyl carbonate', maski ol i gat liklik 'viscosity', ol i gat liklik 'dielectric constants' tu, na dispela i mekim na ol 'lithium salts' i no inap long tanim gut. Olsem na, long redim ol solusen sistem we i gat gutpela 'ionic conductivity', ol i save miksim kain kain solvent, olsem PC+DEC o EC+DMC kombinesen. Ol sol bilong 'lithium', olsem as bilong ol 'lithium ions' insait long 'electrolyte', i save mekim bikpela wok long 'lithium-ion' trenspot long taim bilong sasim na rausim ol 'lithium-ion' bateri. Pefomens bilong ol i save afektim planti samting bilong ol 'lithium-ion' bateri, olsem 'energy density', 'power density', 'operating voltage range', 'cycle life', na sefti. Nau yet, long wok painimaut long laboratori na indastriel wok, ol i save makim ol sol bilong 'lithium' we i gat bikpela 'anionic radii' na bikpela 'redox stability'. Long lukluk long kemikel komposisen bilong ol, ol i ken brukim ol litiam sol i go long tupela lain: ol inorganik litiam sol na ol oganik litiam sol. Ol i bin kamapim sampela 'inorganic lithium salts', olsem LiPF6, LiClO4, LIBF, na LIASF. Tasol, ol i save yusim ol 'organic lithium salts' insait long ol 'lithium-ion' bateri long rot bilong putim ol 'electron-withdrawing groups long ol anions bilong ol dispela 'inorganic lithium salts', olsem 'lithium dioxalato-borate (LiBOB), lithium difluorooxalato-borate ({2}}, O difluorosulfonylimide (LiFSI), na lithium ditrifluoromethylsulfonylimide (LTFSI). Tebol aninit i soim ol 'physicochemical' samting bilong sampela 'lithium salts' we ol i save yusim planti taim insait long ol 'lithium-ion' bateri.
| Kategori | Litiam Sol | Molecular Weight (g/mol) | Em inap long tanim insait long ol 'carbonates'? | Em inap long kapsait long wara? | Electrical Conductivity (1 mol/L, EC/DMC, 20℃) (mS/cm) |
|---|---|---|---|---|---|
| Inogenik Litiam Sol | LiPF₆ | 151.91 | Yes | Yes | 10.00 |
| LiBF₄ | 93.74 | Yes | Yes | 4.50 | |
| LiClO₄ | 106.40 | Yes | Yes | 9.00 | |
| Ol 'organic lithium solts' | LiTFSI | 287.08 | Yes | Yes | 6.18 |
| LiFSI | 187.07 | Yes | Yes | 10.40 | |
| LiBOB | 193.79 | Yes | Yes | 0.65 |
Ol 'additives' em ol samting we ol i save putim long 'electrolyte' long liklik mak (planti taim i no winim 10% long hevi bilong en) we i gat ol wok bilong en na inap long helpim gut ol 'electrochemical' pasin bilong bateri. Long wok bilong ol, ol dispela aditiv i ken bruk i go long planti lain: ol aditiv bilong wokim piksa, ol samting bilong pasim paia, na ol aditiv bilong stopim 'overcharging'. Na tu, i gat ol samting we ol i save yusim long strongim 'conductivity', mekim wok i kamap gut aninit long 'low-temperature kondisen, o bosim ol liklik mak na HF konsentresen insait long 'electrolyte solution'.