Dɛn Ne Battery cell?
Nkwammoaa Nhyehyɛe
Battery biako a wɔsan frɛ no "cell" yɛ battery nhyehyɛe mu ade ketewaa bi. Ɛyɛ cathode (Cathode Electrode), anode (Anode Electrode), electrolyte (Electrolyte), separator (Separator), ne case (Case) titiriw, sɛnea wɔakyerɛ wɔ Mfonini 7-1 mu no.
Wobetumi akyekyɛ electrode krataa a ɛwɔ lithium-ion cell mu no mu sɛ ade a wɔabom ayɛ, titiriw no, ɛwɔ afã anan:
1)Active nneɛma asinasin a intercalate anaasɛ deintercalate lithium ions; cathode asinasin na ɛma lithium fibea no, bere a anode nneɛma nketenkete gye lithium ions.
2)The conductive phase (carbon gel phase) a wɔde afrafra conductive agent ne mprempren collector, a binder som bonding adwuma; ade a wɔde kata so no de ɛlɛtrɔnik fa mprempren boaboafo ne ade a ɛma nsu fa mu no so.
3)Pores a electrolyte ahyɛ mu ma, a ɛyɛ akwan a wɔfa so de lithium-ion fa electrode krataa no mu.
4)Mprempren ɔboaboafo.
Wɔ electrochemical adeyɛ no mu no, electrode coating no fa akwan 4 a edidi so yi ho titiriw:
1)Ɛlektrɔnik akwantuo.
2)Ion akwantuo.
3)Charge nsakrae wɔ electrolyte / electrode abɔde nketenkete ntam, kyerɛ sɛ, electrochemical adeyɛ.
4)Lithium ions a ɛtrɛw wɔ ade a ɛyɛ den no mu. Wɔ microstructure a ɛwɔ electrode krataa no mu no, abɔdeɛ nketenkete kɛseɛ ne ne nkyekyɛmu nya lithium-ion diffusion kwan ne electrochemical reaction no soro beaeɛ pɔtee; pore kɛse ne ne kyekyɛ ka electrolyte no akwantu nhyehyɛe; porosity nya nneɛma a ɛyɛ adwuma dodow ne electrochemical reaction no ani fã pɔtee no so nkɛntɛnso. Saa microstructural su ahorow yi nyinaa awiei koraa no nya battery no adwumayɛ so nkɛntɛnso.
Cathode Nhyehyɛe a Wɔde Yɛ Adwuma
Nkwammoaa mu cathode no yɛ cathode nneɛma te sɛ LiCoO2, conductive agent, binder (PVDF), ne current collector (aluminium a wɔde ayɛ krataa), sɛnea wɔakyerɛ wɔ Mfonini 7-2 mu no.
Wɔ lithium-ion batere ho no, cathode current collector no taa yɛ aluminium foil na anode current collector no yɛkɔbere a wɔde ayɛ krataa. Sɛnea ɛbɛyɛ a mprempren collector no bɛgyina pintinn wɔ battery no mu no, ɛsɛ sɛ abien no nyinaa ahotew boro 98%. Nea enti a lithium-ion battery de aluminium foil di dwuma ma cathode ne kɔbere foil ma anode ne nsɛm 3 a edidi so yi:
1)Kɔbere ne aluminium wɔ anyinam ahoɔden conductivity pa, soft texture, ne bo a ɛba fam. Adwumayɛ nnyinasosɛm a ɛwɔ lithium-ion battery mu yɛ anyinam ahoɔden afiri a ɛdannan nnuru ahoɔden ma ɛbɛyɛ anyinam ahoɔden. Wɔ saa adeyɛ yi mu no, wohia ade bi a ɛbɛma nnuru ahoɔden no akɔ anyinam ahoɔden mu, na ɛno hwehwɛ sɛ wɔde ade a ɛma anyinam ahoɔden kɔ mu. Wɔ nneɛma a wɔtaa de di dwuma mu no, dade na ɛwɔ anyinam ahoɔden a ɛsen biara, na wɔ dade mu no, kɔbere ne aluminium ma ɛyɛ adwuma yiye na ne bo yɛ mmerɛw koraa wɔ kɔbere krataa ne aluminium ntama mu. Wɔ lithium-ion batere mu no, akwan abien titiriw na wɔfa so yɛ adwuma: winding ne stacking. Sɛ wɔde toto stacking ho a, winding hwehwɛ sɛ electrode nkratafa a wɔde siesie batere no nya ahoɔden pɔtee bi de hwɛ hu sɛ electrode nkratafa no rensɛe anaasɛ ɛremmu bere a wɔretwitwa no. Wɔ dade nneɛma mu no, kɔbere ne aluminium ntama yɛ mmerɛw, kɔbere/aluminum ntama a ɛyɛ den kakra no bo yɛ den, kɔbere ne aluminium ntama bo nyɛ den koraa, na kɔbere ne aluminium nneɛma dɔɔso wɔ wiase nyinaa.
2)Kɔbere ne aluminium foils nso yɛ nea ɛyɛ den kakra wɔ mframa mu. Ɛnyɛ den sɛ aluminium ne oxygen a ɛwɔ mframa mu no bɛyɛ adwuma wɔ nnuru mu ma ayɛ oxide film a ɛyɛ den wɔ soro, na ɛmma aluminium no ntumi nyɛ adwuma bio. Saa oxide film a kɔbere/aluminum ayɛ yi nso ma ahobammɔ bi wɔ aluminium a ɛwɔ electrolyte no mu no so. Kɔbere ankasa gyina mframa mu yiye na ne titiriw no, ɛnyɛ nnuru a ɛyɛ adwuma wɔ mframa a ɛyɛ kusuu mu.
3)Cathode ne anode tumi a ɛwɔ lithium-ion battery mu no kyerɛ sɛ wɔde aluminium foil di dwuma ma cathode ne kɔbere foil ma anode, na wontumi nsan wɔn akyi. Cathode tumi no yɛ kɛse, na ɛnyɛ den sɛ kɔbere foil no oxidized wɔ tumi kɛse mu, bere a aluminium wɔ oxidation tumi kɛse ne oxide film a ɛyɛ den wɔ ne soro layer so, a ɛno nso ma ahobammɔ pa ma aluminium a ɛwɔ mu no.
Wɔ dade aluminium ahwehwɛ lattice mu no, kɔbere ne aluminium wɔ akɛse te sɛ Li na ɛnyɛ den sɛ wobetumi ne Li te sɛ LiAl ayɛ dade ntam nneɛma. Li ne Al ntumi nyɛ aduru a ɛwɔ nnuru a wɔde yɛ LiAl nko, na mmom ebetumi nso ayɛ Li2Al4,Li3Al2,Li1Al ne Li2Al afrafrade layers. Saa alloy layers yi di Li dodow bi na ɛsɛe Al ankasa nhyehyɛe ne ne nsɛso, enti wontumi mfa nni dwuma sɛ anode current collector a ɛwɔ lithium-ion batteries mu; bere a Cu ntumi nsɛe pii bere a battery rebɔ-discharge na ɛkura structure ne electrochemical stability mu, na ɛma ɛfata sɛ anode current collector ma lithium-ion battery. Wɔ kɔbere foil a ɛwɔ 3.5V ho no, polarization current no fi ase kɔ soro kɛse na ɛkɔ soro linearly, a oxidation a emu yɛ den ka ho, a ɛkyerɛ sɛ Cu nso fi ase petepete battery no mu; bere a wɔ aluminium foil wɔ polarization tumi kwan no nyinaa so no, polarization current no sua na ɛyɛ pintinn, a wonhu corrosion phenomena biara a ɛda adi pefee, na ɛma electrochemical stability kɔ so. Esiane sɛ Al dodow a ɛpete wɔ cathode tumi kwan a ɛwɔ lithium-ion batere mu no sua koraa na wobetumi akura electrochemical stability mu nti, ɛfata sɛ cathode current collector ma lithium-ion battery.
Oxide a ɛwɔ kɔbere/aluminum ani no yɛ semiconductors dea na ɛde electron kɔ; sɛ oxide layer no yɛ kɛse dodo a, impedance no yɛ kɛse; bere a aluminium oxide a ɛwɔ aluminium no ani no yɛ ade a ɛma anyinam ahoɔden nkɔ mu na entumi nkɔ anyinam ahoɔden, nanso esiane sɛ ɛyɛ teateaa yiye nti, ɛnam tunneling effect no so nya ɛlɛtrɔnik a ɛkɔ mu; sɛ oxide a ɛwɔ mu no yɛ den a, kɔbere/aluminum foil no ntumi nkɔ mu yiye anaasɛ ɛmma mframa nkɔ mu mpo. Mpɛn pii no, ɛsɛ sɛ wɔhohoro kɔbere/aluminum krataa no ho fi oxide a ɛwɔ mu no ho ansa na wɔde adi dwuma de ayi ngo wɔ ɔfã biako ne oxide a ɛyɛ den wɔ ɔfã foforo. Cathode tumi no yɛ kɛse, na aluminium oxide layer no yɛ den yiye, a ebetumi asiw oxidation a ɛwɔ mprempren collector no ano. Oxide layers a kɔbere/nickel ne nea ɛkeka ho no yɛ nea ɛyɛ mmerɛw kakra, ɛnyɛ den sɛ esiw mprempren collector no ano na ɛma battery no yɛ adwuma yiye. Bere koro no ara mu no, anode tumi a ɛwɔ lithium-ion battery mu no sua, na kɔbere/nickel bɛfa oxidation reactions mu, a oxidation/copper/de-lithiation reactions bɛkɔ so wɔ kɔbere/nickel ani, bere a aluminium fa LiAl alloying mu wɔ tumi a ɛkorɔn mu.
Mprempren nea ɔboaboa ano no hwehwɛ sɛ wɔhyehyɛ nneɛma a ɛho tew. Efĩ a ɛwɔ Al mu no bɛma soro film no ayɛ den pii na ama pitting corrosion aba, na nea emu yɛ den mpo no, ɔfasu film no sɛe no ma LiAl alloy ba.
Mprempren nea ɔboaboa ano no hwehwɛ sɛ wɔhyehyɛ nneɛma a ɛho tew. Efĩ a ɛwɔ Al mu no bɛma sini a ɛwɔ soro no ayɛ nea ɛnyɛ den pii, na ɛde pitting corrosion aba, na nea enye koraa no, sini a ɛwɔ soro no sɛe no ma LiAl aduru no ba.
Wɔ lithium-ion batere ho no, wɔatew cathode aluminium foil no so afi 16μm akodu 14μm, afei akɔ 12μm, na mprempren 10μm aluminum foil no reyɛ kɛse dedaw, a ebinom mpo de 8μm di dwuma; wɔ anode kɔbere foil no ho no, ɛnam ne awosu mu a ɛtumi yɛ nsakraeɛ yie nti, wɔatew ne kɛseɛ so afiri 12μm a atwam no so akɔ 10μm, afei akɔ 8μm, na mprempren wɔde 6μm na ɛyɛ batere no fã kɛseɛ no dodoɔ-, berɛ a wɔn a wɔyɛ no binom reyɛ 5μm/4μm a ɛtumi nso tumi de di dwuma. Esiane sɛ lithium-ion batere wɔ ahotew a ɛkorɔn ahwehwɛde ma kɔbere foil a wɔde di dwuma no nti, nneɛma no density titiriw wɔ dodow koro no ara mu. Bere a ne kɛse a wɔreyɛ no so tew no, mpɔtam hɔ density no so tew sɛnea ɛfata, na batere no mu duru fi awosu mu yɛ hare na ɛyɛ hare, na ɛno di lithium-ion batere a wɔhwehwɛ no ho dwuma.
Wɔ mprempren boaboafoɔ fam no, wɔ wɔn kɛseɛ ne wɔn mu duru a ɛka lithium-ion batere akyi no, mprempren boaboafoɔ no ani nso nya nkɛntɛnsoɔ kɛseɛ wɔ batere a wɔyɛ ne ne dwumadie so. Titiriw wɔ anode current collector no fam no, esiane sintɔ ahorow a ɛwɔ ahosiesie mfiridwuma mu nti, kɔbere foils a ɛwɔ gua so no yɛ nea wɔayɛ no roughened a ɛwɔ afã biako, nea wɔayɛ no afã abien-afã abien, ne afã abien-afã abien a wɔayɛ no mmerɛw. Saa asymmetric two-afã nhyehyɛe yi bɛma asymmetric contact resistance a anode coating no wɔ afã abien no nyinaa, na ɛnam so asiw uniform release anode tumi wɔ afã abien no nyinaa; bere koro no ara mu no, asymmetry a ɛwɔ afã abien no nyinaa nso bɛma anode coating no adhesion ahoɔden a ɛnkɔ so pɛpɛɛpɛ aba, na ɛde charge-discharge cycle nkwa nna a ɛnkari pɛ kɛse aba wɔ anode coating no mu wɔ afã abien no nyinaa, a ɛno nso ma battery no tumi porɔw ntɛmntɛm.
Cathode a wɔde yɛ nkwammoaa biako no ne mfiridwuma titiriw a ɛwɔ nkwammoaa no mu. Nhwɛso bi wɔ ase ha:
1)LiCoO2 (10μm): 96.0% na ɛwɔ hɔ.
2)Ade a ɛma nsuo fa nsuo mu (Carbon ECP): 2.0%.
3)Ade a wɔde kyekyere nneɛma (PVDF 761): 2.0%.
4)Adhesion promoter (NMP): Nneɛma a ɛyɛ den no mu duru bɛyɛ 810:1496.
Ahwɛyiye a wɔde yɛ cathode aduru:
1)Cathode slurry viscosity control wɔ 6000cP (1cP=1mPa · s) (ɔhyew 25 digrii ).
2)Ɛsɛ sɛ wɔsesa NMP mu duru no yiye ma ɛne viscosity ahwehwɛde no hyia.
3)Hwɛ nkɛntɛnso titiriw a ɔhyew ne ɔhyew nya wɔ viscosity so.
Cathode ade lithium cobalt oxide: Cathode ade a ɛyɛ adwuma, lithium ion fibea, ma lithium fibea ma batere no. Adeɛ a ɛnyɛ-polar, ne nsɛsoɔ a ɛntene, abɔdeɛ nketenkete kɛseɛ D50 taa yɛ 6-8μm, nsuo a ɛwɔ mu no nnu anaa ɛne 0.2% yɛ pɛ, ɛtaa yɛ alkaline, pH 10-11.
Cathode ade lithium manganese oxide: Adeɛ a ɛnyɛ-polar, ne nsɛsoɔ nyɛ pɛpɛɛpɛ, ne kɛseɛ yɛ D50 mpɛn pii no 5-7μm, nsuo a ɛwɔ mu no nnu anaa ɛyɛ pɛ 0.2%, ɛtaa yɛ alkaline a ɛyɛ mmerɛ, pH bɛyɛ 8.
Conductive agent: Nkɔnsɔnkɔnsɔn-te sɛ ade, nsuo a ɛwɔ mu<1%, particle size generally 1~5um.Superconductive carbon black with excellent conductivity is usually used, such as KetjenblackCarbon ECP and ECP600JD. lts function is to improve the conductivity of the cathode material,compensate for the electronic conductivity of the cathode active material; increase the electrolyteabsorption of the cathode sheet, expand the reaction interface, and reduce polarization.
Binder (PVDF): Adeɛ a ɛnyɛ-polar, ɛte sɛ nkɔnsɔnkɔnsɔn-, molecule mu duru firi 300000 kɔsi3000000; molecule mu duru so tew bere a nsu atwe akyi, na ɛma ɛbata ho yiye. lt wɔde di dwuma de bond lithium cobalt oxide, conductive agent, ne aluminium foil anaa aluminum mesh togethelAdhesion promoter (NMP): Nsu a ɛyɛ mmerɛw a ɛyɛ polar, a wɔde yɛ PVDF a ɛporɔw/ɛhonhon na bere koro no ara mu yɛ slurry no.
Mprempren collector (cathode tab): Wɔde aluminium foil anaa aluminium strip na ɛyɛe.
Anode Nhyehyɛe
Nkwammoaa anode nhyehyɛe no yɛ graphite ade, conductive agent, thickener (CMC), binder (SBR), ne current collector (kɔbere foil), sɛnea wɔakyerɛ wɔ Mfonini 7-3 mu no.
Anode a wɔyɛ wɔ nkwammoaa biako mu nso yɛ nkwammoaa no mfiridwuma atitiriw no mu biako, mpɛn pii no sɛnea edidi so yi:
1)Anode nneɛma (graphite): 94.5%.
2)Ade a ɛma nsuo fa nsuo mu (Carbon ECP): 1.0% (Ketjenblack).
3)Binder (styrene-butadiene rɔba latex, SBR): 2.25%.
4)Nea ɛma ɛyɛ den (carboxymethyl cellulose, CMC): 2.25%.
5)Nsuo: Nneɛma a ɛyɛ den no mu duru yɛ 1600:1417.5.
Ahwɛyiye a wɔde yɛ anode:
1)Anode slurry viscosity control wɔ 5000-6000cP (ɔhyew 25 digrii ).
2)Ɛsɛ sɛ wɔyɛ nsakrae wɔ nsu mu duru mu sɛnea ɛfata na ama wɔadi viscosity ahwehwɛde no ho dwuma.
3)Hwɛ nkɛntɛnso titiriw a ɔhyew ne ɔhyew nya wɔ viscosity so.
Graphite: Anode active material, ade titiriw a ɛyɛ anode reaction, a wɔakyekyɛ mu titiriw ayɛ no akuw atitiriw abien: abɔde mu graphite ne artificial graphite. Nneɛma a ɛnyɛ-polar, a ɛnyɛ den sɛ nneɛma a ɛnyɛ-polar bɛgu ho fĩ, ɛnyɛ den sɛ ɛbɛpete nneɛma a ɛnyɛ -polar mu; ɛnyɛ mmerɛw sɛ wɔbɛtwe nsu, na saa ara nso na ɛnyɛ mmerɛw sɛ wɔbɛpete wɔ nsu mu. Graphite a efĩ wom, bere a wɔapete wɔ nsu mu akyi no, ɛtaa san-agglomerate. Nneɛma nketenkete no kɛse D50 bɛyɛ 20μm. Nneɛma nketenkete no nsusuwii gu ahorow na ne fã kɛse no ara nyɛ nea ɛkɔ so daa, titiriw no ɛyɛ kurukuruwa, ɛyɛ mmerɛw, ɛyɛ nhama, ne nea ɛkeka ho.
Dwumadi ahorow a conductive agent yɛ:
1)Ntu mpɔn conductivity anode krataa no na compensate ɛlɛtrɔnik conductivity anode active ade.
2)Nkɔanim reaction bun ne utilization rate.
3)Siw dendrites awo ntoatoaso ano.
4)Fa nsu-absorbing tumi a conductive nneɛma ma nkɔanim reaction interface na ɛtew polarization (betumi de aka ho anaasɛ ɛnte saa sɛnea graphite particle kɛse kyekyɛ).
Nneɛma a wɔde ka ho: Tew nneyɛe a wontumi nsakra so, ma ahoɔden a ɛkyekyere ne slurry viscosity kɔ soro, na esiw slurry sedimentation ano.
Thickener/anti-settling agent (CMC): Molekyule a ɛkorɔn, ɛnyɛ den sɛ ɛbɛtumi akɔ nsuo ne polar solvents mu.
Isopropanol: Ade a ɛyɛ mmerɛw a ɛwɔ polar; bere a wɔde aka ho akyi no, ebetumi atew polarity a ɛwɔ binder solution no so, ama nhyiam a ɛda graphite ne binder solution ntam no atu mpɔn; wɔ tumi a emu yɛ den a ɛma ɛyɛ fĩ; ɛnyɛ den sɛ ɛbɛma cross-linking a ɛwɔ binder network mu no ayɛ kɛse na ɛma bonding ahoɔden tu mpɔn.
Ethanol: Ade a ɛyɛ mmerɛw a ɛwɔ polar; bere a wɔde aka ho akyi no, ebetumi atew polarity a ɛwɔ binder solution no so, ama nhyiam a ɛda graphite ne binder solution ntam no atu mpɔn; wɔ tumi a emu yɛ den a ɛma ahurututu yɛ frɔmfrɔm; ɛnyɛ den sɛ ɛma linear cross-linking of binder yɛ kɛse na ɛma bonding ahoɔden tu mpɔn (isopropanol ne ethanol dwumadi ahorow no yɛ pɛ titiriw; bere a mass-yɛ no, wobetumi asusuw ɛka ho nneɛma ho de apaw nea wɔde bɛka ho).
Nsu-based binder (SBR): Ɛkyekyere graphite, conductive agent, additives, ne kɔbere foil anaa kɔbere mesh bom; linear chain emulsion molecule, a ɛyɛ den yiye wɔ nsu ne polar solvents mu.
Nsu a wɔayi ion afi mu (anaasɛ nsu a wɔayam): Nsu a wɔde hyɛ mu, a wɔde ka ho dodow a ɛfata no betumi asesa sɛnea nsu a wɔde ayɛ aduru no mu nsu no.
Anode tab: Wɔde kɔbere krataa anaa kɔbere a wɔde abɔ so na ɛyɛe.
