Electrolytes a ɛyɛ den wɔ mfaso pii sen electrolytes a ɛyɛ nsu. Sɛ nhwɛso no, wobetumi abrɛ electrode a ɛsakra bere a wɔrebɔ charge ne discharge no ase, na ama ahobammɔ atu mpɔn. Wɔn nso wɔ gyinabea a ɛkyɛn so, ɛnyɛ den sɛ wɔbɛyɛ ho adwuma, na wonyinlithium a wɔde yɛ adwumadendrites betumi ayɛ ketewaa bi wɔ solvent-free solid polymer electrolytes mu.
Nhwehwɛmu a wɔyɛe wɔ polymer electrolytes ho fii ase wɔ 1973 mu tɔnn, bere a Fenton ne afoforo. hui sɛ polyethylene oxide (PEO) a wɔde alkali dade ayɛ no tumi ma ions kɔ. Efi saa bere no, polymer electrolytes atwetwe adwene kɛse.
Wɔ afe 1978 mu no, Oduruyɛfo Armand hyɛɛ nkɔm sɛ ebia wɔde PEO-based solid-state polymer electrolytes bedi dwuma sɛ electrolytes ama batere.
Wɔ mfeɛ aduonu a ɛdi hɔ no mu no, nhwehwɛmufoɔ de mmɔdenbɔ kɛseɛ suaa ɔkwan a ion fa so kɔ ne abɔdeɛ mu nneɛma a ɛwɔ electrolyte-electrode hyeɛ a ɛwɔ batere no mu no ho adeɛ, na wɔnya nkɔsoɔ pa.
Lithium-ion batere a wɔde solid polymer electrolytes di dwuma no betumi asiw ɔhaw ahorow a ɛfa nsu a ɛtwetwe a ɛbata nsu electrolytes ho no ano.
Ɛnyɛ den sɛ wɔbɛyɛ polymers ho adwuma na wobetumi ayɛ no nketenkete. Esiane sɛ ɛyɛ plasticity a ɛkorɔn nti, wobetumi nso de polymers ayɛ batere a ɛyɛ teateaa-film. Wobetumi de polymer electrolytes ayɛ batere nhyehyɛe ahorow de adi dwumadie ahwehwɛdeɛ ahodoɔ ho dwuma. Bio nso, polymer electrolytes ma nnuru, electrochemical, ne ɔhyew a ɛkorɔn a ɛyɛ den sɛ wɔde toto nsu electrolytes ho a, na ɛne electrode ahorow no nyɛ adwuma wɔ afã kakraa bi na ɛma ɔhyew a ɛtrɛw wɔ adwumayɛ mu. Polymer electrolytes a ɛyɛ mmerɛw no betumi asiw nsakrae a ɛba electrode ahorow no mu bere a wɔde charge ne discharge rebɔ no ano, na ama battery nhyehyɛe no agyina. Enti, bere a wɔde nsu-ion batere adi gua akyi no, lithium-ion batere mfiridwuma a egyina polymer electrolytes so no bɛkɔ so ntɛmntɛm na wɔanya aguadi a edi mu.
Akwan pii wɔ hɔ a wɔfa so kyekyɛ polymer electrolytes mu, na gyinapɛn ahorow no gu ahorow. Mprempren, wɔda nsow titiriw wɔ polymer electrolytes a ɛyɛ den mu sɛnea polymer ko a wɔde di dwuma te, te sɛ polyether-based polyethylene oxide (PEO) a agye din sen biara, ne polymethyl methacrylate (PMMA) ne polyacrylonitrile (PAN) nso. Sɛ yɛbɛka no ɔkwan biara so a, ɛsɛ sɛ polymer electrolytes di tebea horow a edidi so yi ho dwuma na ama wɔde adi dwuma ankasa wɔ lithium-ion batere mu.
Ionic conductivity a ɛkorɔn
Lithium-ion a wɔde kɔ baabi foforo nɔma a wosusuw ho
Mfiri ahoɔden pa
Mfɛnsere a ɛtrɛw a ɛfa anyinam ahoɔden ho
Nnuru ne ɔhyew a ɛma ɛyɛ den yiye
Wɔ mprempren polymer electrolyte nhyehyɛe ahorow mu no, polymers da ahwehwɛ kɛse adi wɔ dan mu hyew mu, na ɛno na ɛkyerɛkyerɛ nea enti a polymer electrolytes a ɛyɛ den no tumi a ɛkɔ dan mu hyew mu no sua koraa sen nsu electrolyte de no mu. Ahwehwɛ dodow no ara a ɛwɔ polymers mu no yɛ spherulites, na mmeae a ɛnyɛ nsɛ wɔ wɔn ntam. Wɔtaa gye di sɛ lithium-ion a ɛkɔ no ba titiriw wɔ saa mmeae a ɛnyɛ nsɛ yi.
Enti, nteaseɛ a ɛfa phase structure a ɛwɔ polymers mu no boa ma adesua a ɛfa lithium-ion conduction mechanism ho.
Wɔ binary polymer electrolyte nhyehyɛe ahorow ho no, phase nhyehyɛe no titiriw yɛ ahorow abien: crystalline mpɔtam ne amorphous mpɔtam. Crystalline mpɔtam a wɔhyehyɛ no yɛ kinetically driven na ɛne ahosiesie tebea pɔtee ne bere wɔ abusuabɔ tẽẽ. Sɛ yɛbɛka no katee a, esiane sɛ ahwehwɛ mmeae a ɛwɔ polymer nhyehyɛe no mu, ne nsakrae kɛse a ɛwɔ mmeae yi a ɛwɔ tebea horow mu nti, sɛ wɔde toto sɛnea polymer electrolytes ahorow no tumi fa mu no ho a, ɛnyɛ nyansahu mu ade kɛse. Nanso, wɔ tebea horow bi mu no, sɛ ahwehwɛ mmeae nyin brɛoo na ionic conductivity mu deviation no wɔ baabi a wogye tom a, conductivity a wɔde toto ho no yɛ nea wogye tom. Eyi nti na yɛtaa de nneɛma ahorow a efi mu ba toto ho no.
Esiane sɛ spherulites nyin wɔ polymer no mu no gyina bere- so nti, ionic conductivity a ɛwɔ ɔhyew a ɛba fam sen polymer no nwene no nso gyina bere- so. Bio nso, lithium-ion conductivity a ɛwɔ polymer electrolytes mu no ne ɔhyew dodow, onwini dodow, ne bere a wɔde gye wɔn ahome no wɔ abusuabɔ. Sɛ nhwɛso no, bere tenten a wɔde gye wɔn ahome no ma polymer ahwehwɛ nhyehyɛe a edi mũ ne ahwehwɛ a ɛkorɔn, na ɛma ionic conductivity so tew nkakrankakra kodu nea ɛba fam koraa bere a bere a wɔde gye wɔn ahome no kɔ soro no. Saa ara nso na onwini a ɛyɛ brɛoo no ma ɛyɛ ahwehwɛ a edi mũ, na ionic conductivity a ɛne no hyia no nso bɛtew nkakrankakra akodu nea ɛba fam koraa.
Sɛ yɛfa binary solid polymer electrolyte a ɛwɔ PEO ne LiCIO4 sɛ nhwɛso a, saa nhyehyɛe yi kura phase nhyehyɛe ahorow pii. Nea edi kan no, LiClO4 ne PEO tumi yɛ nneɛma ahorow a ɛyɛ den, a PEO6-LiCIO4, PEO3-LiCIO4, PEO2-LiCIO4, ne PEO-LiClO4 ka ho. Wɔn mu bi ne sɛ, sɛ O:Li=10:1 a, PEO6-LiCIO4 tumi ne PEO yɛ eutectic, a ne melting point yɛ 50℃. Nea ɛka ho no, sɛ wɔma ɔhyew no kɔ soro kodu digrii 160 , wobetumi ayɛ eutectic kɛse bi. Bere a wɔreyɛ onwini no, eutectic kɛse no bɛma spherulites ahorow abiɛsa aba: nea edi kan no nwene boro digrii 120 na nkyene pii wom; nea ɛto so abien no nwene digrii 45 kosi 60 , nkyene nni mu, na ɛyɛ nkakrankakra; nea ɛto so abiɛsa no wɔ nea ɛyɛ hyew a ɛba fam kakra sen host polymer no na ɛyɛ ntɛmntɛm. Nhwehwɛmu ne nhwehwɛmu kyerɛ sɛ: ɛbɛyɛ sɛ spherulite a edi kan ne PEO3-LiCIO4; nea ɛto so abien no betumi ayɛ PEO-LiCIO4 ne PEO3-LiCIO4 afrafra; na nea ɛto so abiɛsa no ne PEO ankasa hyia. Bio nso, lithium nkyene a ɛwɔ mu ne ɔhyew a wɔde yɛ no nyinaa betumi ama nsakrae aba nhyehyɛe mu.
Polymer electrolytes yɛ polymer nneɛma a ɛyɛ adwuma a ɛwɔ ionic conductivity a ɛkorɔn, a ɛnam complexation reactions a ɛda polymers ne metal salts ntam a wɔde polymers di dwuma sɛ matrix no so na ɛba. Ɛgyina polymer matrix so no, polymer electrolytes a wɔtaa de di dwuma no bi ne PEO-based polymer electrolytes, PVDE-based polymer electrolytes, PMMA-based polymer electrolytes, ne afoforo. Nea ɛnte sɛ inorganic solid-state electrolytes no, polymer electrolytes yɛ hare, ɛyɛ den, na ɛyɛ den. Te sɛ inorganic solid-state electrolytes no, ɛnyɛ sɛ polymer electrolytes de ions kɔ lithium-ion batere mu nko na mmom ɛyɛ adwuma sɛ battery separators nso. Polymer electrolytes titiriw wɔ mfaso horow a edidi so yi:
Ebetumi adi ɔhaw a ɛfa lithium dendrite a ɛba wɔ lithium-ion batere mu no ho dwuma yiye
Ɛbɛtumi ayɛ nsakraeɛ yie wɔ deformation no mu bere a wɔrebɔ lithium-ion batere no charge ne discharge
Ebetumi atew nnuru a ɛkɔ so wɔ electrolyte ne electrode nneɛma a ɛwɔ lithium-ion batere mu no so anaasɛ ayi afi hɔ mpo
Ɛwɔ ahobammɔ adwumayɛ a ɛkorɔn
Nneɛma a ɛyɛ den a lithium nkyene ahorow (a LBF4, LIPF6, LiCFSO4, ne LiASF6 ka ho) ne PEO yɛ no te sɛ nea LiCIO4 na ɛyɛ no titiriw, a ɛkyerɛ sɛ lithium nkyene ko no nni nkɛntɛnso biara tẽẽ wɔ nkyene ko a wɔde PEO ayɛ no so. Titiriw no, LiBF betumi ne PEO ayɛ nsɛnnennen abien: PEO4-LIBF ne PEO,S-LiBF. Sɛ O/Li ratio no yɛ 16 ne 20 a, PEO2.5-LIBF4 betumi ne PEO ayɛ eutectic. LPF6 nso tumi ne PEO yɛ complex abien: PEO6-LiPF6 ne PEO:-LiPF6. Nneɛma abien a LiASF6 ne PEO ayɛ no te sɛ LiPF6 de no, nanso ɛwɔ nsunsuanso a ɛkorɔn kakra. Anion lithium nkyene akɛse nso betumi ne PEO ayɛ complexes, nanso kinetics no yɛ brɛoo kɛse. Bio nso, nhyɛso no nso ka ahwehwɛ nyin kodu baabi. Nhyɛso a ɛkɔ soro ma spherulite nyin, ɛtew beae a ɛnyɛ nsɛ no so, na sɛnea ɛne no hyia no, ɛtew lithium-ion a ɛkɔ nipadua no mu no so.