Amabhethri e-lithium azohlangana nezindawo ezahlukahlukene ngesikhathi sokusetshenziswa kwawo. Ebusika, izinga lokushisa enyakatho yeChina livame ukuba ngaphansi kuka-0℃ noma ngisho -10℃. Lapho izinga lokushisa lokushaja nokukhipha lebhethri lehliswa ngaphansi kuka-0℃, umthamo wokushaja nokukhipha kanye nomthamo webhethri le-lithium kuzokwehla kakhulu. Lokhu kungenxa yokuthi ukuhamba kwe-lithium ion ku-electrolyte, i-SEI kanye nezinhlayiya ze-graphite kunciphisa izinga lokushisa eliphansi. Isimo esinjalo sokushisa esiphansi esiqinile sizoholela nakanjani emvuleni yensimbi ye-lithium enendawo ethile ephezulu.

Imvula ye-lithium enendawo ethile ephezulu ingesinye sezizathu ezibaluleke kakhulu zendlela yokuhluleka kwamabhethri e-lithium, kanye nenkinga ebalulekile yokuphepha kwebhethri. Lokhu kungenxa yokuthi inendawo enkulu kakhulu, insimbi ye-lithium iyasebenza kakhulu futhi iyavutha, indawo ephakeme ye-dendrite lithium umoya omncane omanzi ungashiswa.

Ngokuthuthuka komthamo webhethri, ububanzi kanye nesabelo semakethe sezimoto zikagesi, izidingo zokuphepha zezimoto ezisebenza ngogesi ziya ngokuya ziba nzima. Yiziphi izinguquko ekusebenzeni kwamabhethri amandla emazingeni okushisa aphansi? Yiziphi izici zokuphepha okufanele wazi?

1.18650 isilingo somjikelezo we-cryogenic kanye nokuhlaziywa kokuhlakazwa kwebhethri

Ibhethri le-18650 (2.2A, NCM523/ graphite system) lilingiswe kuzinga lokushisa eliphansi elingu-0℃ ngaphansi kwendlela ethile yokushaja-yokukhipha. Indlela yokushaja neyokukhiphayo yile: Ukushaja kwe-CC-CV, izinga lokushaja ngu-1C, i-voltage enqamula ukushaja ingu-4.2V, i-curging cut-off current ingu-0.05c, bese ikhipha i-CC iye ku-2.75V. Njengoba ibhethri i-SOH engu-70% -80% ngokuvamile ichazwa njengesimo sokuqedwa (EOL) sebhethri. Ngakho-ke, kulokhu kuhlolwa, ibhethri liyanqanyulwa lapho i-SOH yebhethri ingu-70%. Ijika lomjikelezo webhethri ngaphansi kwezimo ezingenhla liboniswa kuMfanekiso 1 (a). Ukuhlaziywa kwe-Li MAS NMR kwenziwa ezigxotsheni kanye ne-diaphragms yamabhethri ajikelezayo nangajikelezayo, futhi imiphumela yokuxoshwa kwamakhemikhali iboniswe ku-Figure 1 (b).

Umfanekiso 1. Ijika lomjikelezo weseli kanye nokuhlaziywa kwe-Li MAS NMR

Amandla omjikelezo we-cryogenic anda emijikelezweni embalwa yokuqala, elandelwa ukwehla okuqhubekayo, futhi i-SOH yehla ngaphansi kwe-70% emijikelezweni engaphansi kwe-50. Ngemva kokuhlakaza ibhethri, kwatholakala ukuthi kwakukhona ungqimba lwempahla yesiliva-grey ebusweni be-anode, okwakucatshangwa ukuthi iyinsimbi ye-lithium efakwe ebusweni bezinto ezijikelezayo ze-anode. Ukuhlaziywa kwe-Li MAS NMR kwenziwa kumabhethri amaqembu amabili wokuqhathanisa okuhlola, futhi imiphumela yaqinisekiswa futhi kuMfanekiso B.

Kukhona ukuphakama okubanzi ku-0ppm, okubonisa ukuthi i-lithium ikhona ku-SEI ngalesi sikhathi. Ngemuva komjikelezo, inani eliphakeme lesibili livela ku-255 PPM, okungenzeka ukuthi lakhiwe ukuna kwensimbi ye-lithium ebusweni bezinto ze-anode. Ukuqinisekisa okwengeziwe ukuthi i-lithium dendrites ivele ngempela yini, i-SEM morphology yabonwa, futhi imiphumela yaboniswa kuMfanekiso 2.

Isithombe

Umfanekiso 2. Imiphumela yokuhlaziywa kwe-SEM

Ngokuqhathanisa izithombe A no-B, kungabonakala ukuthi ungqimba oluqinile lwento kwakheka esithombeni B, kodwa lolu ungqimba aluzange lumboze ngokuphelele izinhlayiya zegraphite. Ukukhulisa i-SEM kuye kwanwetshwa futhi inaliti efana nempahla yabonwa kuMfanekiso D, okungenzeka kube yi-lithium enendawo ethile ephezulu (eyaziwa nangokuthi i-dendrite lithium). Ngaphezu kwalokho, i-lithium metal deposition ikhula ibheke ku-diaphragm, futhi ukushuba kwayo kungabonwa ngokuyiqhathanisa nobukhulu bongqimba lwegraphite.

Indlela ye-lithium efakwe kuyo incike ezintweni eziningi. Njengokuphazamiseka kwendawo, ukuminyana kwamanje, isimo sokushaja, izinga lokushisa, izithasiselo ze-electrolyte, ukwakheka kwe-electrolyte, i-voltage esetshenzisiwe nokunye. Phakathi kwazo, ukujikeleza kwezinga lokushisa eliphansi kanye nokuminyana okuphezulu kwamanje kulula kakhulu ukwenza insimbi ye-lithium eqinile enendawo ethile ephezulu.

2. Ukuhlaziywa kokuzinza kwe-thermal kwe-electrode yebhethri

I-TGA yasetshenziselwa ukuhlaziya ama-electrode ebhethri angasetshenzisiwe nangemuva kokujikeleza, njengoba kuboniswe kuMfanekiso 3.

Isithombe

Umfanekiso 3. Ukuhlaziywa kwe-TGA kwama-electrode angalungile kanye nama-electrode (A. I-electrode engalungile B. I-electrode enhle)

Njengoba kungabonwa esithombeni esingenhla, i-electrode engasetshenziswanga ineziqongo ezintathu ezibalulekile ku-T≈260℃, 450℃ naku-725℃ ngokulandelana, okubonisa ukuthi ukubola okunobudlova, ukuhwamuka noma ukusabela kwe-sublimation kwenzeka kulezi zindawo. Kodwa-ke, ukulahlekelwa okukhulu kwe-electrode kwakusobala ku-33 ℃ naku-200 ℃. Ukusabela kokubola ekushiseni okuphansi kubangelwa ukubola kwe-membrane ye-SEI, yiqiniso, kuhlobene nokubunjwa kwe-electrolyte nezinye izici. Imvula yensimbi ye-lithium enendawo ethize ephezulu iholela ekwakhekeni kwenani elikhulu lamafilimu e-SEI ebusweni bensimbi ye-lithium, okuyisizathu futhi sokulahlekelwa okukhulu kwamabhethri ngaphansi komjikelezo wokushisa ophansi.

I-SEM ayikwazanga ukubona izinguquko ku-morphology yezinto ze-cathode ngemva kokuhlolwa komjikelezo, futhi ukuhlaziywa kwe-TGA kubonise ukuthi kube nokulahlekelwa kwekhwalithi ephezulu ngenkathi izinga lokushisa lingaphezu kuka-400℃. Lokhu kulahlekelwa okukhulu kungase kubangelwe ukuncishiswa kwe-lithium ku-cathode material. Njengoba kuboniswe kuMfanekiso 3 (b), ngokuguga kwebhethri, okuqukethwe kwe-Li ku-electrode enhle ye-NCM kuncipha kancane kancane. Ukulahlekelwa okukhulu kwe-SOH100% ye-electrode eqondile ngu-4.2%, kanti lokho kwe-SOH70% ye-electrode ephozithivu kungu-5.9%. Ngamafuphi, izinga lokulahlekelwa okukhulu kokubili kwama-electrode amahle nabi likhuphuka ngemva komjikelezo we-cryogenic.

3. Ukuhlaziywa kokuguga kwe-Electrochemical kwe-electrolyte

Umthelela wezinga lokushisa eliphansi ku-electrolyte yebhethri lahlaziywa yi-GC/MS. Amasampula e-electrolyte athathwe kumabhethri angagugi namadala ngokulandelana, futhi imiphumela yokuhlaziywa kwe-GC/MS yaboniswa kuMfanekiso 4.

Isithombe

Umfanekiso 4.GC/MS kanye nemiphumela yokuhlolwa kwe-FD-MS

I-electrolyte yebhethri yomjikelezo we-non-cryogenic iqukethe i-DMC, i-EC, i-PC, ne-FEC, i-PS, ne-SN njengezihlanganisi zokuthuthukisa ukusebenza kwebhethri. Inani le-DMC, i-EC ne-PC kuseli elingajikelezi neseli elizungezayo liyafana, kanye nesengezo se-SN ku-electrolyte ngemva kokujikeleza (okuvimbela ukubola kwe-positive electrode electrolytic liquid oxygen ngaphansi kwamandla aphezulu) siyehla. , ngakho-ke isizathu siwukuthi i-electrode eqondile ishajwa ngokweqile ngaphansi komjikelezo wokushisa ophansi. I-BS ne-FEC yizithasiselo ezakha ifilimu ye-SEI, ezikhuthaza ukwakheka kwamafilimu e-SEI azinzile. Ngaphezu kwalokho, i-FEC ingathuthukisa ukuzinza komjikelezo kanye nokusebenza kahle kwe-Coulomb yamabhethri. I-PS ingathuthukisa ukuzinza okushisayo kwe-anode SEI. Njengoba kubonakala esithombeni, inani le-PS alinciphi ngokuguga kwebhethri. Kube nokwehla okukhulu kwenani le-FEC, futhi lapho i-SOH ingu-70%, i-FEC ayikwazanga ngisho nokubonwa. Ukunyamalala kwe-FEC kubangelwa ukwakhiwa kabusha okuqhubekayo kwe-SEI, futhi ukwakhiwa kabusha okuphindaphindiwe kwe-SEI kubangelwa imvula eqhubekayo ye-Li endaweni ye-cathode graphite.

Umkhiqizo oyinhloko we-electrolyte ngemva komjikelezo webhethri yi-DMDOHC, ukwakheka kwayo okuhambisana nokwakheka kwe-SEI. Ngakho-ke, inani elikhulu le-DMDOHC ku-FIG. I-4A isho ukwakheka kwezindawo ezinkulu ze-SEI.

4. Ukuhlaziywa kokuzinza okushisayo kwamabhethri omjikelezo we-non-cryogenic

Ukuhlolwa kwe-ARC (Accelerated calorimeter) kwenziwa kumjikelezo we-non-cryogenic namabhethri omjikelezo we-cryogenic ngaphansi kwezimo ze-quasi-adiabatic kanye nemodi ye-HWS. Imiphumela ye-Arc-hws ibonise ukuthi ukusabela kwe-exothermic kudalwe ingaphakathi lebhethri, ngaphandle kwezinga lokushisa elingaphandle. Ukusabela ngaphakathi kwebhethri kungahlukaniswa izigaba ezintathu, njengoba kukhonjisiwe kuThebula 1.

Isithombe

Ukumuncwa ukushisa okuncane kwenzeka ngesikhathi sokushisa kwe-diaphragm nokuqhuma kwebhethri, kodwa ukufudumala kwe-diaphragm akunakwa kuyo yonke i-SHR. Ukusabela kokuqala kwe-exothermic kuvela ekuhlehleni kwe-SEI, okulandelwa ukungeniswa kokushisa ukuze kuholele ukushumeka kwe-lithium ion, ukufika kwama-electron endaweni yegraphite, kanye nokunciphisa ama-electron ukuze kumiswe kabusha ulwelwesi lwe-SEI. Imiphumela yokuhlolwa kokuzinza kwe-thermal iboniswa kuMfanekiso 5.

Isithombe

Isithombe

Umfanekiso 5. Imiphumela ye-Arc-hws (a) 0%SOC; (b) amaphesenti angama-50 e-SOC; (c) i-SOC engamaphesenti ayi-100; Imigqa enamadeshi izinga lokushisa lokuqala le-exothermic, izinga lokushisa lokuqala elishisayo kanye nezinga lokushisa elishisayo.

Isithombe

Umfanekiso 6. Incazelo yemiphumela ye-arc-hws a. Izinga lokushisa elishisayo, ukuqalisa kwe-B.ID, C. Izinga lokushisa lokuqala le-thermal runnaway d. Izinga lokushisa lokuqala lokusabela kwe-exothermic

Ukusabela kokuqala kwe-exothermic (OER) kwebhethri ngaphandle komjikelezo we-cryogenic kuqala cishe ku-90℃ futhi kwenyuke ngokulandelana kuye ku-125℃, ngokuncipha kwe-SOC, okubonisa ukuthi i-OER incike kakhulu esimweni se-lithium ion ku-anode. Ebhethrini enqubweni yokukhipha, i-SHR (izinga lokuzifudumeza ngokwalo) eliphakeme kakhulu ekuphenduleni kokubola likhiqizwa cishe ku-160 ℃, futhi i-SHR izokwehla ngezinga lokushisa eliphezulu, ngakho-ke ukusetshenziswa kwama-ion e-lithium ahlanganisiwe kunqunywa ku-electrode engemihle. .

Uma nje kukhona i-lithium ion eyanele ku-electrode engalungile, kuqinisekisiwe ukuthi i-SEI eyonakele ingakhiwa kabusha. Ukubola okushisayo kwe-cathode material kuzokhulula umoya-mpilo, ozokhipha i-oxidize nge-electrolyte, ekugcineni kuholele ekuziphatheni kokuphuma okushisayo kwebhethri. Ngaphansi kwe-SOC ephakeme, impahla ye-cathode isesimweni se-delithium kakhulu, futhi ukwakheka kwe-cathode material nakho akuzinzile kakhulu. Okwenzekayo ukuthi ukuzinza okushisayo kwengqamuzana kuncipha, inani le-oxygen ekhishwe liyakhula, futhi ukusabela phakathi kwe-electrode enhle ne-electrolyte kuthatha izinga lokushisa eliphezulu.

4. Ukukhululwa kwamandla ngesikhathi sokukhiqiza igesi

Ngokuhlaziywa kwebhethri langemuva komjikelezo, kungabonakala ukuthi i-SHR iqala ukukhula ngomugqa oqondile cishe ku-32℃. Ukukhululwa kwamandla ohlelweni lokukhiqiza igesi kubangelwa ikakhulukazi ukusabela kokubola, okuvame ukucatshangwa ukuthi ukubola okushisayo kwe-electrolyte.

Insimbi ye-lithium enendawo ethile ephezulu idlula phezu kwempahla ye-anode, engavezwa ngezibalo ezilandelayo.

Isithombe

Emphakathini, i-Cp inamandla okushisa athile, futhi △T imelela isamba sokukhuphuka kwezinga lokushisa elizishisisa ngokwakho kwebhethri okubangelwa ukubola kokubola ekuhlolweni kwe-ARC.

Amandla athile okushisa amaseli angajikeleziwe phakathi kuka-30 ℃ no-120℃ ahlolwe ekuhlolweni kwe-ARC. Ukusabela kwe-exothermic kwenzeka ku-125 ℃, futhi ibhethri isesimweni sokuphuma, futhi akukho okunye ukusabela kwe-exothermic okukuphazamisayo. Kulesi sivivinyo, i-CP inobudlelwano bomugqa nezinga lokushisa, njengoba kuboniswe kuzibalo ezilandelayo.

Isithombe

Isamba samandla esikhishwe kukho konke ukusabela singatholwa ngokuhlanganisa umthamo wokushisa othize, ongu-3.3Kj ngeseli ukuguga kweseli emazingeni okushisa aphansi. Inani lamandla akhishwe ngesikhathi sokushisa okushisayo alikwazi ukubalwa.

5. Ukuhlolwa kwe-acupuncture

Ukuze kuqinisekiswe umthelela wokuguga kwebhethri ekuhlolweni kokujikeleza okufushane kwebhethri, kwenziwa ukuhlolwa kwenaliti. Imiphumela yokuhlolwa iboniswa esithombeni esingezansi:

Isithombe

Ngokuqondene nomphumela we-acupuncture, A izinga lokushisa elingaphezulu kwebhethri phakathi nenqubo yokutshopa, futhi B izinga lokushisa eliphakeme elingafinyelelwa.

Kungabonakala emfanekisweni ukuthi kunomehluko omncane kuphela we-10-20 ℃ phakathi kwebhethri eliguga ngemva kokukhishwa kanye nebhethri elisha (i-SOC 0%) ngokuhlolwa kokudinga. Kuseli elikhulile, izinga lokushisa eliphelele lifinyelela ku-T≈35℃ ngaphansi kwesimo se-adiabatic, esihambisana ne-SHR≈0.04K/min.

Ibhethri elingagugile lifinyelela izinga lokushisa eliphezulu elingu-120℃ ngemva kwemizuzwana engu-30 lapho i-SOC ingu-50%. Ukushisa kwe-joule okukhishiwe akwanele ukufinyelela leli zinga lokushisa, futhi i-SHR idlula inani lokusabalalisa ukushisa. Uma i-SOC ingu-50%, ibhethri eliguga linomphumela wokulibaziseka othize ekubalekeni okushisayo, futhi izinga lokushisa likhuphuka ngokucijile liye ku-135℃ lapho inaliti ifakwa ebhethrini. Ngaphezulu kuka-135 ℃, ukwanda kwe-SHR kubangela ukuphuma okushisayo kwebhethri, futhi izinga lokushisa elingaphezulu lebhethri likhuphukela ku-400℃.

Okuhlukile kwabonwa lapho ibhethri elisha lishajwa ngokuhlaba inaliti. Amanye amaseli alahlekelwa ngokuqondile ukulawula ukushisa, kuyilapho amanye awazange alahlekelwe ukulawula ukushisa lapho izinga lokushisa elingaphezulu ligcinwe ngaphansi kuka-125 ℃. Okukodwa kokulawula okushisayo kwebhethri ngemuva kwenaliti ebhethrini, izinga lokushisa elingaphezulu lifinyelele ku-700 ℃, okwenza ukuthi ucwecwe lwe-aluminium luncibilike, ngemuva kwemizuzwana embalwa, isigxobo sancibilika futhi sahlukaniswa nebhethri, sase sithungela i-ejection. yegesi, futhi ekugcineni yabangela igobolondo lonke libe bomvu. Amaqembu amabili ezinto ezihlukene kungacatshangwa ukuthi i-diaphragm incibilika ku-135 ℃. Uma izinga lokushisa lingaphezulu kuka-135℃, i-diaphragm iyancibilika bese kuvela isifunda esifushane sangaphakathi, sikhiqize ukushisa okwengeziwe futhi ekugcineni kuholele ekubalekeni okushisayo. Ukuze uqinisekise lokhu, ibhethri elingashisi elibalekayo lahlakazwa futhi i-diaphragm yahlolwa i-AFM. Imiphumela yabonisa ukuthi isimo sokuqala sokuncibilika kwe-membrane sivele ezinhlangothini zombili ze-membrane, kodwa isakhiwo se-porous sisabonakala ohlangothini olubi, kodwa hhayi ohlangothini oluhle.