Iibhetri zeLithium-ion zezona bhetri zesibini ezikhula ngokukhawuleza emva kweebhetri zenickel-cadmium kunye nenickel-hydrogen. Iimpawu zayo eziphezulu zamandla zenza ukuba ikamva layo libonakale liqaqambileyo. Nangona kunjalo, iibhetri ze-lithium-ion azifezekanga, kwaye ingxaki yabo enkulu ukuzinza kwemijikelezo yabo yokukhutshwa kwentlawulo. Eli phepha lishwankathela kwaye lihlalutye izizathu ezinokwenzeka zokuphelelwa amandla kweebhetri ze-Li-ion, kubandakanywa ukugqithisa, ukuchithwa kwe-electrolyte kunye nokuzikhupha.

Iibhetri zeLithium-ion zinamandla ahlukeneyo okunxibelelana xa ukuhlangana kwee-electrode kusenzeka phakathi kwee-electrode ezimbini, kwaye ukuze kufumaneke ukusebenza kakuhle kwebhetri, ubungakanani bomthamo wee-electrodes ezimbini ezibambayo kufuneka zigcine ixabiso elilinganayo.

Kwiibhetri ze-lithium-ion, ibhalansi yomthamo ibonakaliswa njengomlinganiselo wobunzima be-electrode efanelekileyo kwi-electrode engalunganga,

Oko kukuthi: γ=m+/m-=ΔxC-/ΔyC+

Kule fomyula ingentla, i-C ibhekisela kwi-theoretical coulombic capacity ye-electrode, kwaye Δx kunye ne-Δy ibhekisela kwinani le-stoichiometric ye-lithium ion efakwe kwi-electrode engalunganga kunye ne-electrode efanelekileyo, ngokulandelanayo. Inokubonwa kwifomula engentla ukuba umlinganiselo ofunekayo wobunzima beepali ezimbini kuxhomekeke kumthamo weCoulomb ohambelana nezibonda ezimbini kunye nenani leeyoni ze-lithium eziguqulwayo.

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Ngokuqhelekileyo, umlinganiselo omncinci wobunzima ukhokelela ekusebenziseni okungaphelelanga kwezinto ze-electrode ezimbi; umlinganiselo omkhulu wobunzima unokubangela ingozi yokhuseleko ngenxa yokugqithiswa kwe-electrode engalunganga. Ngamafutshane, kumlinganiselo wobunzima olungiselelweyo, ukusebenza kwebhetri yeyona nto ilungileyo.

Kwinkqubo yebhetri ye-Li-ion efanelekileyo, ibhalansi yamandla ayitshintshi ngexesha lokujikeleza kwayo, kwaye umthamo wokuqala kumjikelezo ngamnye ixabiso elithile, kodwa imeko yangempela inzima kakhulu. Nayiphi na indlela yokusabela esecaleni enokuvelisa okanye idle ii-ion ze-lithium okanye ii-electron zingakhokelela kutshintsho kwibhalansi yebhetri. Nje ukuba amandla ebhetri atshintshe imeko, olu tshintsho alunakuguqulwa kwaye lunokuqokelelana ngemijikelo emininzi, okukhokelela ekusebenzeni kwebhetri. Impembelelo enzulu. Kwiibhetri ze-lithium-ion, ngaphezu kweempendulo ze-redox ezenzeka xa i-lithium ion ichithwa, kukho nenani elikhulu leempendulo zecala, ezifana nokuchithwa kwe-electrolyte, ukuchithwa kwezinto ezisebenzayo kunye ne-metallic lithium deposition.

Isizathu 1: Ukutshaja ngaphezulu

1. Ukusabela kwe-overcharge ye-graphite negative electrode:

Xa ibhetri igcwele kakhulu, ii-ion ze-lithium ziyancipha ngokulula kwaye zifakwe kumphezulu we-electrode engalunganga:

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I-lithium egciniweyo igubungela umphezulu we-electrode engalunganga, ivalela ukudityaniswa kwe-lithium. Oku kukhokelela ekunciphiseni ukusebenza kakuhle kokukhutshwa kunye nokulahleka kwamandla ngenxa:

① Ukunciphisa ubungakanani be-lithium enokuphinda isetyenziswe;

②I-lithium yensimbi egciniweyo iphendula kunye ne-solvent okanye i-electrolyte exhasayo ukwenza i-Li2CO3, i-LiF okanye ezinye iimveliso;

③ I-lithium yesinyithi idla ngokuqulunqwa phakathi kwe-electrode engalunganga kunye ne-separator, enokuthi ivimbele ii-pores ze-separator kunye nokwandisa ukuchasana kwangaphakathi kwebhetri;

④ Ngenxa yendalo esebenzayo ye-lithium, kulula ukusabela nge-electrolyte kwaye idle i-electrolyte, okukhokelela ekunciphiseni ukusebenza kakuhle kokukhutshwa kunye nokulahlekelwa kwamandla.

Ukutshaja ngokukhawuleza, ukuxinana kwangoku kukhulu kakhulu, i-electrode engafanelekanga i-polarized kakhulu, kwaye ukubekwa kwe-lithium kuya kubonakala ngakumbi. Oku kunokwenzeka xa izinto ezisebenzayo ze-electrode zigqithise xa zithelekiswa ne-electrode negative esebenzayo. Nangona kunjalo, kwimeko yezinga eliphezulu lokutshaja, i-deposition ye-lithium yensimbi inokuthi yenzeke nangona umlinganiselo wezinto ezisebenzayo kunye nezingalunganga ziqhelekileyo.

2. I-positive electrode reaction reaction

Xa umlinganiselo wezinto ezisebenzayo ze-electrode ukuya kwi-negative electrode esebenzayo uphantsi kakhulu, i-electrode eyakhayo inokuthi yenzeke.

Ukulahlekelwa kwamandla okubangelwa ukugqithiswa kwe-electrode echanekileyo kubangelwa ikakhulu ukuveliswa kwezinto ezingenayo i-electrochemically (ezifana ne-Co3O4, i-Mn2O3, njl.), eyonakalisa ibhalansi yamandla phakathi kwee-electrodes, kwaye ukulahlekelwa kwamandla akunakubuyiselwa.

(1) LiyCoO2

LiyCoO2→(1-y)/3[Co3O4＋O2(g)]＋yLiCoO2 y<0.4

Ngelo xesha, i-oksijeni eyenziwa ngokuchithwa kwezinto ezilungileyo ze-electrode kwibhetri ye-lithium-ion etywiniweyo iqokelela ngexesha elifanayo ngenxa yokuba akukho mpendulo yokubuyisela kwakhona (njengesizukulwana se-H2O) kunye negesi evuthayo eyenziwa yi-decomposition. ye-electrolyte, kwaye iziphumo aziyi kucingelwa.

(2) λ-MnO2

Ukusabela kwe-lithium-manganese kwenzeka xa i-lithium-manganese oxide incinyiwe ngokupheleleyo: λ-MnO2→Mn2O3+O2(g)

3. I-electrolyte i-oxidized xa i-overcharged

Xa uxinzelelo luphezulu kune-4.5V, i-electrolyte iya kuba ne-oxidized ukuvelisa i-insolubles (njenge-Li2Co3) kunye neegesi. Ezi zi-insolubles ziya kuthintela i-micropores ye-electrode kwaye zithintele ukufuduka kwe-lithium ion, okubangela ukulahlekelwa kwamandla ngexesha lokuhamba ngebhayisikili.

Izinto ezichaphazela isantya se-oxidation:

Indawo yomphezulu wezinto ezintle ze-electrode

Imathiriyeli yangoku yomqokeleli

I-ejenti eyongeziweyo (i-carbon black, njl.)

Uhlobo kunye nommandla wekhabhoni emnyama

Phakathi kwe-electrolyte esetyenziswa ngokuqhelekileyo, i-EC/DMC ithathwa njengeyona nto iphezulu yokumelana ne-oxidation. Inkqubo ye-electrochemical oxidation yesisombululo ibonakaliswa ngokubanzi njenge: isisombululo→imveliso ye-oxidation (irhasi, isisombululo kunye nombandela oqinileyo)+ne-

I-oxidation yayo nayiphi na i-solvent iya kwandisa i-electrolyte concentration, iyancipha ukuzinza kwe-electrolyte, kwaye ekugqibeleni ichaphazele umthamo webhetri. Ukucinga ukuba ixabiso elincinci le-electrolyte lisetyenziswa rhoqo xa lihlawuliswa, i-electrolyte eninzi iyafuneka ngexesha lokuhlanganisa ibhetri. Kwisitya esingaguqukiyo, oku kuthetha ukuba inani elincinci lezinto ezisebenzayo lilayishiwe, okubangela ukuhla kwamandla okuqala. Ukongezelela, ukuba kuveliswa imveliso eqinileyo, ifilimu yokugqithisa iya kwenziwa phezu kwendawo ye-electrode, eya kwandisa i-polarization yebhetri kunye nokunciphisa umbane wokukhupha ibhetri.

Isizathu 2: Ukubola kwe-Electrolyte (ukunciphisa)

Ndibolisa kwi-electrode

1. I-electrolyte ibolile kwi-electrode elungileyo:

I-electrolyte ine-solvent kunye ne-electrolyte exhasayo. Emva kokuba i-cathode ichithekile, iimveliso ezingenakunyibilika ezifana ne-Li2Co3 kunye ne-LiF zivame ukubunjwa, ezinciphisa amandla ebhetri ngokuthintela ama-pores e-electrode. Ukusabela kokunciphisa i-electrolyte kuya kuba nefuthe elibi kumthamo kunye nobomi bomjikelezo webhetri. Igesi eveliswa kukunciphisa inokunyusa uxinzelelo lwangaphakathi lwebhetri, olunokubangela iingxaki zokhuseleko.

I-voltage ye-electrode efanelekileyo yokubola idla ngokuba nkulu kune-4.5V (vs. Li/Li +), ngoko ke ayiboli ngokulula kwi-electrode elungileyo. Ngokuchasene noko, i-electrolyte ichithwa ngokulula kwi-electrode engalunganga.

2. I-electrolyte ibolile kwi-electrode engeyiyo:

I-electrolyte ayizinzile kwi-graphite kunye nezinye i-lithium-inserted carbon anode, kwaye kulula ukusabela ukuvelisa umthamo ongenakukwazi ukuguqulwa. Ngethuba lokuqala lokuhlawuliswa kunye nokukhutshwa, ukuchithwa kwe-electrolyte kuya kwenza ifilimu ye-passivation ebusweni be-electrode, kwaye ifilimu ye-passivation ingahlula i-electrolyte kwi-carbon negative electrode ukukhusela ukubola okuqhubekayo kwe-electrolyte. Ngaloo ndlela, ukuzinza kwesakhiwo se-carbon anode kugcinwa. Ngaphantsi kweemeko ezifanelekileyo, ukunciphisa i-electrolyte kunqunyelwe kwisigaba sokwenza ifilimu ye-passivation, kwaye le nkqubo ayinakwenzeka xa umjikelezo uzinzile.

Ukuqulunqwa kwefilimu ye-passivation

Ukunciphisa i-electrolyte salts ithatha inxaxheba ekubunjweni kwefilimu ye-passivation, enenzuzo ekuzinzisweni kwefilimu yokugqithisa, kodwa

(1) Umba ongenakunyibilika oveliswa ngokunciphisa uya kuba nefuthe elibi kwimveliso yokunciphisa i-solvent;

(2) Ukuxinwa kwe-electrolyte kunciphisa xa ityuwa ye-electrolyte iyancipha, ekugqibeleni ikhokelela ekulahlekelweni kwamandla ebhetri (i-LiPF6 iyancitshiswa ukuba yenze i-LiF, i-LixPF5-x, i-PF3O kunye ne-PF3);

(3) Ukuqulunqwa kwefilimu ye-passivation kudla i-lithium ion, okuya kubangela ukungalingani kwamandla phakathi kwee-electrode ezimbini ukunciphisa umthamo othile webhetri yonke.

(4) Ukuba kukho iintanda kwifilimu ye-passivation, iimolekyuli ze-solvent zinokungena kwaye zigqithise ifilimu ye-passivation, engadli nje kuphela i-lithium eninzi, kodwa inokuthintela i-micropores kwi-carbon surface, okubangelwa ukungakwazi ukufakwa kwe-lithium kwaye ikhutshiwe. , okukhokelela ekulahlekelweni kwamandla okungenakuguqulwa. Ukongeza ezinye izongezo ze-inorganic kwi-electrolyte, njenge-CO2, i-N2O, i-CO, i-SO2, njl., inokukhawulezisa ukubunjwa kwefilimu ye-passivation kunye nokuvimbela ukufakwa kunye nokubola kwe-solvent. Ukongezwa kwezithsaba ze-ether organic additives nazo zinefuthe elifanayo. Izithsaba ezili-12 kunye ne-ether ezi-4 zezona zingcono.

Izinto zokulahleka komthamo wefilimu:

(1) Uhlobo lwekhabhoni esetyenzisiweyo kwinkqubo;

(2) Ukwakhiwa kwe-Electrolyte;

(3) Izongezo kwii-electrodes okanye i-electrolytes.

I-Blyr ikholelwa ukuba i-ion exchange reaction iqhubela phambili ukusuka kumphezulu we-particle esebenzayo ukuya kumbindi wayo, isigaba esitsha esakhiweyo singcwaba i-original material esebenzayo, kunye nefilimu ye-passive ene-ionic ephantsi kunye ne-electronic conductivity yenziwa kumphezulu we-particle. i-spinel emva kogcino I-polarization enkulu kunangaphambi kokugcinwa.

U-Zhang wafumanisa ukuba ukuchasana komgangatho we-surface passivation layer kwaye i-interfacial capacitance iyancipha ngokunyuka kwenani lemijikelezo. Ibonisa ukuba ubukhulu bomgca we-passivation buyanda kunye nenani lemijikelo. Ukuchithwa kwe-manganese kunye nokubola kwe-electrolyte kukhokelela ekwakhiweni kweefilimu ze-passivation, kunye neemeko zobushushu obuphezulu zinceda ngakumbi kwinkqubela phambili yezi mpendulo. Oku kuya kwandisa ukuchasana koqhagamshelwano phakathi kwezinto ezisebenzayo kunye nokuxhatshazwa kokufuduka kwe-Li +, ngaloo ndlela kwandisa i-polarization yebhetri, ukutshaja okungaphelelanga kunye nokukhupha, kunye nokunciphisa umthamo.

IINdlela zokuNcitshiswa kwe-Electrolyte

I-electrolyte ihlala iqulethe i-oksijeni, amanzi, i-carbon dioxide kunye nezinye izinto ezingcolileyo, kunye neempendulo ze-redox zenzeka ngexesha lokutshaja kunye nokukhupha ibhetri.

Indlela yokunciphisa i-electrolyte ibandakanya iinkalo ezintathu: ukunciphisa i-solvent, ukunciphisa i-electrolyte kunye nokunciphisa ukungcola:

1. Ukunciphisa isinyibilikisi

Ukuncitshiswa kwePC kunye ne-EC kubandakanya ukusabela kwe-electron enye kunye nenkqubo yokusabela kwee-electron ezimbini, kunye ne-electron reaction reaction form Li2CO3:

Fong et al. wayekholelwa ukuba ngexesha lokuqala lokukhutshwa, xa amandla e-electrode asondele kwi-0.8V (vs. Li / Li +), i-electrochemical reaction ye-PC / EC yenzeke kwigraphite ukuvelisa i-CH = CH = CH3 (g) / CH2 = CH2 ( g) kunye ne-LiCO3(s), ekhokelela kwilahleko yesakhono esingenakujikwa kwii-electrode zegraphite.

Aurbach et al. iqhube uphando olubanzi kwindlela yokunciphisa kunye neemveliso ze-electrolyte ezahlukeneyo kwi-electrode yensimbi ye-lithium kunye ne-carbon-based electrode, kwaye yafumanisa ukuba i-electron reaction mechanism ye-PC ivelisa i-ROCO2Li kunye nepropylene. I-ROCO2Li inovelwano kakhulu ekulandeleni amanzi. Iimveliso eziphambili ziyi-Li2CO3 kunye nepropylene phambi kokulandelela amanzi, kodwa akukho Li2CO3 iveliswa phantsi kweemeko ezomileyo.

Ukubuyiselwa kwe-DEC:

U-Ein-Eli Y wabika ukuba i-electrolyte exutywe ne-diethyl carbonate (DEC) kunye ne-dimethyl carbonate (i-DMC) iya kusabela ngokutshintshiselana kwibhetri ukuvelisa i-ethyl methyl carbonate (EMC), ejongene nokulahlekelwa kwamandla. impembelelo ethile.

2. Ukunciphisa i-Electrolyte

Ukusabela kokunciphisa i-electrolyte ngokuqhelekileyo kuthathwa njengokubandakanyeka ekubunjweni kwefilimu ye-carbon electrode surface film, ngoko ke uhlobo lwayo kunye nokugxininiswa kuya kuchaphazela ukusebenza kwe-carbon electrode. Kwezinye iimeko, ukuncitshiswa kwe-electrolyte kunegalelo ekuzinzisweni kwendawo yekhabhoni, enokuthi yenze i-passivation layer efunekayo.

Ngokuqhelekileyo kukholelwa ukuba i-electrolyte exhasayo ilula ukunciphisa kune-solvent, kwaye imveliso yokunciphisa ixutywe kwifilimu ye-electrode engafanelekanga kwaye ichaphazela ukubola kwamandla ebhetri. Iimpendulo ezininzi zokunciphisa ukuxhasa i-electrolyte zezi zilandelayo:

3. Ukunciphisa ukungcola

(1) Ukuba umxholo wamanzi kwi-electrolyte uphezulu kakhulu, i-LiOH (s) kunye ne-Li2O idiphozithi iya kwenziwa, engabandakanyi ukufakwa kwee-ion ze-lithium, okukhokelela ekulahlekelweni kwamandla okungenakuguqulwa:

H2O＋e→OH-＋1/2H2

OH-＋Li+→LiOH(ii)

LiOH+Li++e-→Li2O(s)+1/2H2

I-LiOH (s) eyenziweyo ifakwe kwi-electrode surface, yenze ifilimu engaphezulu enokumelana okuphezulu, ethintela ukudibanisa kwe-Li + kwi-electrode yegraphite, okubangela ukulahlekelwa kwamandla okungenakuguqulwa. Umlinganiselo omncinci wamanzi (100-300 × 10-6) kwi-solvent ayinayo impembelelo ekusebenzeni kwe-electrode yegraphite.

(2) I-CO2 kwi-solvent ingancitshiswa kwi-electrode engafanelekanga ukwenza i-CO kunye ne-LiCO3 (s):

2CO2+2e-+2Li+→Li2CO3+CO

I-CO iya kwandisa uxinzelelo lwangaphakathi lwebhetri, kwaye i-Li2CO3 (s) iya kwandisa ukuchasana kwangaphakathi kwebhetri kwaye ichaphazele ukusebenza kwebhetri.

(3) Ubukho be-oksijini kwi-solvent buya kwenza i-Li2O

1/2O2+2e-+2Li+→Li2O

Ngenxa yokuba umahluko onokwenzeka phakathi kwe-metallic lithium kunye ne-carbon intercalated ngokupheleleyo incinci, ukunciphisa i-electrolyte kwi-carbon kufana nokunciphisa i-lithium.

Isizathu 3: Ukuzikhupha ngokwakho

Ukuzikhupha ngokwakho kubhekisa kwinto yokuba ibhetri iphulukana namandla ayo ngokwemvelo xa ingasetyenziswa. Ukuzikhupha kwebhetri ye-Li-ion kukhokelela ekulahlekelweni kwamandla kwiimeko ezimbini:

Enye yilahleko yesakhono esibuyiselwa umva;

Okwesibini kukulahlekelwa ngumthamo ongenakuguqulwa.

Ilahleko yesakhono esibuyiselwa umva kuthetha ukuba umthamo olahlekileyo unokufunyanwa kwakhona ngexesha lokutshaja, ngelixa ilahleko yesakhono engenakubuyiseka ichasene. I-electrodes efanelekileyo kunye ne-negative inokusebenza njenge-microbattery kunye ne-electrolyte kwimeko ehlawulisiweyo, okubangelwa ukudibanisa i-lithium ion kunye ne-deintercalation, kunye ne-intercalation kunye ne-deintercalation ye-electrodes efanelekileyo kunye ne-negative. I-ion ze-lithium edibeneyo zihambelana kuphela ne-lithium ion ye-electrolyte, ngoko ke amandla e-electrodes afanelekileyo kunye ne-negative ayilingani, kwaye le nxalenye yokulahlekelwa kwamandla ayikwazi ukufunyanwa ngexesha lokutshaja. Njenge:

I-lithium manganese oxide i-electrode entle kunye ne-solvent iya kubangela i-micro-battery effect kunye nokuzikhupha ngokwakho, okukhokelela kwilahleko yesakhono engenakulungiseka:

LiyMn2O4+xLi++xe-→Liy+xMn2O4

Iimolekyuli zokunyibilikisa (ezinje ngePC) zifakwe ioksijini kumphezulu wekhabhoni emnyama okanye umqokeleli wangoku njenge-anode ye-microbattery:

xPC→xPC-radical+xe-

Ngokufanayo, izinto ezisebenzayo ezingasebenziyo zinokusebenzisana ne-electrolyte ukubangela ukuzikhupha kwaye kubangele ilahleko yesakhono esingenakuguqulwa, kwaye i-electrolyte (efana ne-LiPF6) iyancitshiswa kwizinto eziqhubayo:

PF5+xe-→PF5-x

I-Lithium carbide kwindawo ehlawuliswayo i-oxidized ngokususa i-lithium ion njenge-electrode engalunganga ye-microbattery:

LiyC6→Liy-xC6+xLi++++xe-

Izinto ezichaphazela ukuzikhupha ngokwakho: inkqubo yokwenziwa kwezinto ezilungileyo ze-electrode, inkqubo yokwenziwa kwebhetri, iipropathi ze-electrolyte, ubushushu kunye nexesha.