Kodi electrolyte mu batri ya lithiamu ndi chiyani?

Kodi electrolyte mu batri ya lithiamu ndi chiyani?

electrolyte

Ma electrolyte mu batri ya lithiamu-ndi yomwe imanyamula ma ayoni mu batire. Nthawi zambiri amapangidwa ndi mchere wa lithiamu, zosungunulira za organic, ndi zowonjezera, monga momwe zikusonyezedwera pa Chithunzi 7-4. Elekitiroliti imagwira ntchito yofunika kwambiri pochititsa ma ion pakati pa ma elekitirodi abwino ndi opanda ma elekitirodi a batri ya lithiamu-, kuonetsetsa ubwino wake monga magetsi okwera kwambiri ndi mphamvu zenizeni. Ma elekitiroliti amapangidwa mosiyanasiyana malinga ndi mmene zinthu zilili komanso mochuluka kuchokera ku-zosungunulira zoyera, mchere wa lifiyamu, ndi zowonjezera zofunika. Ngakhale zida za electrode zimatsimikizira kuchuluka kwa mphamvu ya batri, ma electrolyte amatsimikizira moyo wake wozungulira, kutentha kwambiri komanso kutsika, komanso chitetezo. Zolemba zazikulu za electrolyte zimakhalabe zosasinthika; luso makamaka lagona pakupanga buku la mchere wa lithiamu ndi zowonjezera, komanso kumvetsetsa mozama za njira zamakina ophatikizika ndi njira zomwe zimakhudzidwa ndi mabatire a lithiamu-ion.

Pali mitundu yambiri ya mchere wa lifiyamu, monga momwe zasonyezedwera pa Chithunzi 7-5, koma ndi ochepa kwambiri amene amagwiritsidwa ntchito m'mabatire a lithiamu-ion omwe amapezeka pamalonda. Mchere wabwino wa lithiamu uyenera kukhala ndi zinthu zotsatirazi:

1) Digiri yocheperako yolumikizana, yosungunuka mosavuta mu zosungunulira za organic, kuwonetsetsa kuti ma electrolyte ali ndi ma ionic apamwamba.

2) Anions ndi antioxidant ndi kuchepetsa kukana; zinthu zochepetsera zimathandizira kupanga filimu yokhazikika, yotsika-yotsutsa ya SEI.

3) Kukhazikika kwamankhwala kwabwino, osayambitsa zoyipa zoyipa ndi zida zama electrode, ma electrolyte, kapena zolekanitsa.

4) Njira yosavuta yokonzekera, yotsika mtengo, yopanda-yopanda poizoni ndi kuipitsa{2}}kwaulere.

LiPF6 ndiye mchere wa lithiamu womwe umagwiritsidwa ntchito kwambiri. Ngakhale mawonekedwe ake pawokha sakhala opambana kwambiri, amawonetsa magwiridwe antchito abwino kwambiri mu ma electrolyte osakanikirana a carbonate. LiPF6 ili ndi maubwino otsatirawa:

1) Kusungunuka koyenera ndi kupangika kwa ayoni kwambiri muzosungunulira zosakhala-zamadzi.

2) Iwo akhoza kupanga khola passivation filimu padziko zotayidwa zojambulazo otolera panopa.

3) Iwo synergistically amapanga khola SEI filimu pa graphite elekitirodi pamwamba ndi zosungunulira carbonate.

Komabe, LiPF6 ilibe kukhazikika kwamafuta ndipo imakonda kuwonongeka. Zomwe zimapangidwira zimatha kuwononga filimu ya SEI pamtunda wa elekitirodi, kusungunula ma elekitirodi abwino, ndikupangitsa kuwonongeka kwa mphamvu panthawi yanjinga.

LiBF ndiwowonjezeranso mchere wa lithiamu. Poyerekeza ndi LiPF6, LiBF ili ndi kutentha kwina kochulukira, -kukhazikika kokhazikika, komanso kutsika kwambiri-kutsika kwambiri. LiBF ili ndi ma conductivity apamwamba, zenera lalikulu la electrochemical, komanso kukhazikika kwamafuta. Ubwino wake waukulu wagona pakupanga filimu{6}} yake, chifukwa imatha kutenga nawo gawo popanga filimu ya SEI.

Kapangidwe kake, LiDFOB ili ndi theka la-mamolekyu a LiBOB ndi LiBF, kuphatikiza ubwino wa filimu yabwino-kupanga katundu wa LiBOB ndi -kutsika kwa kutentha kwa LiBF4. Poyerekeza ndi LiBOB, LiDFOB ili ndi kusungunuka kwapamwamba muzitsulo zosungunulira za carbonate komanso ma electrolyte apamwamba kwambiri. Kutentha kwake-kutsika ndi kutsika-ndibwinoko kuposa LiPF4, ndipo imagwirizana bwino ndi batire ya cathode, kupanga filimu yodutsa pamwamba pa aluminiyumu yojambulapo ndi kulepheretsa electrolyte oxidation.

Magulu a CF₃SO₂ mu dongosolo la LiTFSI ali ndi mphamvu yochotsa ma elekitironi-, zomwe zimakulitsa kutsika kwa mtengo woyipa ndikuchepetsa kuphatikizika kwa ion, zomwe zimapangitsa kuti mcherewo ukhale wosungunuka kwambiri. Kuphatikiza apo, LiTFSI ili ndi mphamvu yamagetsi yamagetsi, kutentha kwapang'onopang'ono kwapang'onopang'ono, ndipo sikumapangidwa ndi hydrolyzed; komabe, idzawononga kwambiri otolera amakono a aluminiyamu pamagetsi opitilira 3.7V.

Ma atomu a fluorine mu molekyu ya LiFSI ali ndi ma elekitironi amphamvu{{0}ochotsa zinthu, zomwe zimachititsa kuti maatomu asokonezeke pa N, zomwe zimapangitsa kuti ma ion asamayende bwino komanso kupatukana kwa Li+, motero kumapangitsa kuti pakhale kusinthasintha kwakukulu.

LiPO2F2 imawonetsa kutsika kwabwino-kutsika komanso imawongolera-kutentha kwapamwamba kwa electrolyte. Monga chowonjezera, imatha kupanga filimu ya SEI yolemera mu LixPOyFz ndi LiF pamtunda woipa wa electrode, womwe umathandizira kuchepetsa kusakanikirana kwa batri ndikuwongolera kayendedwe ka batri. Komabe, LiPO2F2 imakhalanso ndi kusungunuka kochepa.

Chigawo chachikulu chamadzi electrolytendi organic zosungunulira, amene amasungunula mchere lithiamu ndi kupereka chonyamulira kwa lithiamu ayoni. Chosungunulira chabwino cha batri la lithiamu{1}} cha electrolyte cha ion chiyenera kukwaniritsa zinthu izi:

1) Kutha kwamphamvu kwa dielectric komanso kusungunuka kwamphamvu kwa mchere wa lithiamu.

2) Malo osungunuka otsika ndi malo otentha kwambiri, kusunga madzi pa kutentha kwakukulu.

3) Kukhuthala kochepa, kumathandizira mayendedwe a lithiamu-ion.

4) Kukhazikika kwamankhwala abwino, sikuwononga ma elekitirodi abwino kapena oyipa kapena kusungunula zinthu zabwino ndi zoyipa zama elekitirodi.

5) Kung'anima kwapamwamba, chitetezo chabwino, mtengo wotsika,{{1}zopanda poizoni komanso{2}}zosaipitsa.

Zosungunulira zomwe zimagwiritsidwa ntchito mu lithiamu-ma electrolyte a batri ya ion amagawidwa makamaka kukhala zosungunulira za carbonate ndi organic ether solvents, monga momwe zikusonyezera Chithunzi 7-6. Kuti mupeze -elekitiloti ya batri ya lithiamu-ion yogwira ntchito kwambiri, nthawi zambiri imagwiritsidwa ntchito chosungunulira chokhala ndi zosungunulira ziwiri kapena kuposerapo, zomwe zimawathandiza kuti azithandizana komanso azigwira bwino ntchito. Maonekedwe a zosungunulira za carbonate wamba akuwonetsedwa mu Table 7-1.

Tebulo 7-1 Katundu Wakuthupi Wazosungunulira Za Carbonate Wamba

Zosungunulira za organic ether makamaka zimaphatikiza ma etha a unyolo monga 1,2-dimethoxypropane (DMP), dimethoxymethane (DMM), ndi ethylene glycol dimethyl ether (DME), ndi ma cyclic ether monga tetrahydrofuran (THF) ndi 2-methyltetra-Methyl furan (2-). Pazitsulo zosungunulira unyolo wa ether, utali wa carbon chain, umakhala wokhazikika bwino wa mankhwala, koma kukwezeka kwa mamasukidwe amphamvu komanso kutsika kwa lifiyamu-ion migration rate. Ethylene glycol dimethyl ether imatha kupanga chelate yokhazikika (LiPF6·DME) yokhala ndi lithiamu hexafluorophosphate, kuwonetsa mphamvu yosungunuka ya mchere wa lithiamu ndikupangitsa kuti ma electrolyte apangidwe kwambiri. Komabe, DME ili ndi kusakhazikika bwino kwamankhwala ndipo silingapange filimu yokhazikika yokhazikika pamwamba pa zinthu zopanda ma elekitirodi.

Zosungunulira za carbonate zimaphatikizapo ma cyclic carbonates monga propylene carbonate (PC) ndi ethylene carbonate (EC), ndi ma chain carbonates monga dimethyl carbonate (DMC), diethyl carbonate (DEC), ndi methyl ethyl carbonate (EMC). Ma cyclic carbonates amakhala ndi dielectric pafupipafupi, zomwe zimapangitsa kuti mchere wa lifiyamu usungunuke, komanso umakhala ndi kukhuthala kwakukulu, zomwe zimapangitsa kuti ma lithiamu{1}}atsika amasamuka. Ma chain carbonates amakhala ndi dielectric yocheperako komanso yofooka ya mchere wa lithiamu, koma kukhathamira kochepa komanso kuyenda bwino, kumathandizira kusamuka kwa lithiamu{3}}.

Mitundu ya flame-zowonjezera zotsalira za lithiamu{1}}ion electrolyte ikuwonetsedwa pa Chithunzi 7-7. Zowonjezera, zomwe zimagwiritsidwa ntchito pang'ono, zimakhala ndi mphamvu zambiri ndipo ndi njira yochepetsera ndalama komanso yothandiza yowongolerera magwiridwe antchito a mabatire a lithiamu{5}}ion. Powonjezera kachulukidwe kakang'ono ka ma electrolyte a lithiamu-mabatire a ion, mawonekedwe ena a batri amatha kuwongoleredwa, monga mphamvu yosinthira, kuyenderana ndi ma elekitirodi/electrolyte, kayendedwe kake, kuchuluka kwa magwiridwe antchito, ndi magwiridwe antchito achitetezo, kuchita mbali yofunika kwambiri mu mabatire a lithiamu{8}. Chowonjezera chabwino cha lithiamu-ion batire electrolyte chiyenera kukhala ndi makhalidwe anayi awa:

1) Kusungunuka kwakukulu mu zosungunulira za organic.

2) Zochepa zimatha kusintha kwambiri mawonekedwe amodzi kapena angapo.

3) Palibe zoyipa zomwe zimachitika ndi zida zina za batri zomwe zimakhudza magwiridwe antchito a batri.

4) Zotsika mtengo, zopanda-zopanda poizoni kapena poizoni.

Kutengera ndi momwe zimagwirira ntchito, zowonjezera zitha kugawidwa m'magulu owonjezera, zowonjezera zoteteza kuchulukitsitsa, zoletsa moto, filimu ya SEI-kupanga zowonjezera, zoteteza ma cathode, zolimbitsa thupi za LiPF6, ndi zina zowonjezera.

Zowonjezera ma conductive amathandizira kuti mabatire a lithiamu{0}}agwire ntchito bwino polumikizana ndi ayoni a electrolyte, kulimbikitsa kusungunuka kwa mchere wa lifiyamu, ndi kuonjezera mphamvu ya electrolyte. Chifukwa zowonjezera zowonjezera zimagwira ntchito pogwiritsa ntchito machitidwe ogwirizanitsa, amatchedwanso ligand additives, ndipo amagawidwa kukhala anionic ligands, cationic ligands, ndi mitsempha yopanda ndale kutengera ion yolumikizana.

Zowonjezera zotetezera zochulukira zimateteza kuchulukirachulukira kapena kukulitsa kulolerana ndi kuchulukirachulukira. Amagawidwa m'magulu a redox ndi zowonjezera za monomer. Pakadali pano, zowonjezera za redox makamaka ndi mndandanda wa anisole, womwe uli ndi kuthekera kwakukulu kwa redox komanso kusungunuka kwabwino. Zowonjezera za monomer zimakumana ndi ma polymerization pansi pa voteji yayikulu, kutulutsa mpweya, ndipo ma polima amayala pamwamba pa cathode, kusokoneza kulipiritsa. Zowonjezera za monomer makamaka zimaphatikizapo mankhwala onunkhira monga xylene ndi phenylcyclohexane.

Zowonjezera zobwezeretsanso moto zimagwira ntchito pokweza poyatsira ma electrolyte kapena kuletsa ma free radical chain reaction omwe amaletsa kuyaka. Mitundu yawo ikuwonetsedwa pachithunzi 7-8. Kuonjezera zoletsa moto ndi imodzi mwa njira zofunika kwambiri zochepetsera kuyaka kwa electrolyte, kukulitsa kutentha kwa mabatire a lithiamu-ion, ndikuwongolera magwiridwe antchito awo. Njira zopangira zowonjezera zowonjezera moto zimakhala ziwiri:

1) Popanga gawo lotsekereza pakati pa gawo la gasi ndi gawo lofupikitsidwa, amaletsa kuyaka m'magawo onse okhazikika komanso gasi.

2) Amagwira ma radicals aulere panthawi yamoto, ndikuthetsa machitidwe owopsa a unyolo omwe amalepheretsa kuyaka pakati pa magawo a mpweya.