Tun lokacin da batirin lithium-ion suka shiga kasuwa, an yi amfani da su sosai saboda fa’idodinsu na tsawon rayuwa, babban takamaiman iya aiki, kuma babu tasirin ƙwaƙwalwa. Ƙananan zafin amfani da batirin lithium-ion yana da matsaloli kamar ƙarancin ƙarfi, raguwa mai tsanani, rashin aikin sake zagayowar, bayyananniyar jigon lithium, da cirewar lithium mara kyau. Koyaya, tare da ci gaba da faɗaɗa filayen aikace-aikacen, matsalolin da ke haifar da ƙarancin ƙarancin zafin batirin lithium-ion suna ƙara fitowa fili.

A cewar rahotanni, ƙarfin fitar da batirin lithium-ion a -20 ° C shine kawai 31.5% na abin da ke cikin dakin da zafin jiki. Yanayin zafin aiki na batura lithium-ion na gargajiya yana tsakanin -20 da +55 °C. Koyaya, a fagen sararin samaniya, masana’antar soja, motocin lantarki, da sauransu, ana buƙatar baturi don yin aiki akai-akai a -40 ° C. Sabili da haka, yana da mahimmanci don inganta ƙananan yanayin zafi na batir Li-ion.

Dalilan Ƙuntata Ƙarƙashin Ayyukan Batir Li-ion

A cikin ƙananan yanayin zafi, danko na electrolyte yana ƙaruwa har ma da wani bangare yana ƙarfafawa, yana haifar da raguwa a cikin tafiyar da batir lithium-ion.

Daidaituwa tsakanin electrolyte da mummunan lantarki da mai rarrabawa ya zama matalauta a cikin ƙananan yanayin zafi.

Mummunan lantarki na batirin lithium-ion yana da hazo lithium mai tsanani a ƙarƙashin yanayin ƙarancin zafin jiki, kuma ƙarfen lithium ɗin da aka haɗe yana amsawa tare da electrolyte, kuma jigon samfurin sa yana haifar da haɓaka cikin kauri na ƙayyadaddun ƙayyadaddun wutar lantarki (SEI).

A cikin ƙananan yanayin zafi, tsarin watsawa na batir Li-ion a cikin kayan aiki yana raguwa, kuma juriya na canja wurin caji (Rct) yana ƙaruwa sosai.

Tattaunawa akan Abubuwan da suka Shafi Ayyukan Batir Li-ion ƙarancin zafin jiki

Ra’ayi na ƙwararru 1: Electrolyte yana da tasiri mafi girma akan ƙarancin yanayin zafi na batir lithium-ion, kuma abun da ke ciki da physicochemical Properties na electrolyte suna da tasiri mai mahimmanci akan ƙarancin yanayin zafi na baturi. Matsalolin da batirin ke fuskanta a cikin ƙananan zafin jiki shine: dankowar electrolyte zai ƙaru, kuma saurin tafiyar da ion zai kasance a hankali, wanda zai haifar da rashin daidaituwa na gudun hijirar lantarki na waje, don haka baturin ya zama polarized sosai. kuma ana rage karfin caji da fitarwa sosai. Musamman lokacin da ake yin caji a ƙananan zafin jiki, ions lithium cikin sauƙi suna samar da lithium dendrites a saman ƙarancin lantarki, yana haifar da gazawar baturi.

Ƙarƙashin yanayin zafi na electrolyte yana da alaƙa kusa da girman ƙaddamarwa na electrolyte kanta. Electrolyte tare da high conductivity yana watsa ions cikin sauri kuma yana iya yin ƙarin ƙarfi a ƙananan zafin jiki. Mafi rarrabuwar gishirin lithium a cikin electrolyte, mafi girman adadin ƙaura kuma mafi girman ɗawainiya. Mafi girman ƙarfin wutar lantarki, saurin tafiyar da ion, ƙarancin polarization, kuma mafi kyawun aikin baturi a ƙananan zafin jiki. Sabili da haka, mafi girman ƙarfin lantarki shine yanayin da ake buƙata don cimma kyakkyawan aikin ƙarancin zafin jiki na batir lithium-ion.

Halin da ake amfani da shi na electrolyte yana da alaƙa da abun da ke cikin electrolyte, kuma rage danko na sauran ƙarfi yana daya daga cikin hanyoyin da za a inganta halayen electrolyte. Kyakkyawan ruwa na kaushi a ƙananan zafin jiki shine garantin jigilar ion, kuma fim ɗin mai ƙarfi na electrolyte da aka kafa ta hanyar electrolyte a mummunan lantarki a ƙananan zafin jiki kuma shine mabuɗin don rinjayar jagorancin lithium ions, kuma RSEI shine babban rashin ƙarfi. na batirin lithium ion a cikin ƙananan yanayin zafi.

Masanin 2: Babban abin da ke iyakance ƙarancin aikin batir lithium-ion shine haɓaka juriya na Li + mai ƙarfi a ƙananan yanayin zafi, ba fim ɗin SEI ba.

Ƙananan kayan zafin jiki na kayan cathode don baturan lithium ion

1. Low zafin jiki Properties na Layered cathode kayan

Tsarin da aka shimfiɗa ba wai kawai yana da ƙimar da ba zai misaltu ba na tashoshi na lithium ion diffusion mai girma ɗaya, amma kuma yana da kwanciyar hankali na tsarin tashoshi mai girma uku. Shine farkon kayan cathode na kasuwanci don batirin lithium ion. Abubuwan da ke wakiltar su sune LiCoO2, Li (Co1-xNix) O2 da Li (Ni, Co, Mn) O2 da sauransu.

Xie Xiaohua et al. ya ɗauki LiCoO2/MCMB a matsayin abin bincike kuma ya gwada halayen cajin-ƙananan zafin sa.

Sakamakon ya nuna cewa tare da raguwar zafin jiki, dandalin watsawa ya sauke daga 3.762V (0 ° C) zuwa 3.207V (-30 ° C); Jimlar ƙarfin baturi kuma yana raguwa sosai daga 78.98mA·h (0°C) zuwa 68.55mA·h (-30°C).

2. Ƙananan yanayin zafi na kayan aikin cathode da aka tsara na spinel

Tsarin kashin baya LiMn2O4 kayan cathode yana da fa’idodin ƙarancin farashi da rashin guba saboda bai ƙunshi sinadarin Co.

Koyaya, valence sauye-sauye na Mn da tasirin Jahn-Teller na Mn3+ yana haifar da rashin daidaituwar tsari da ƙarancin juzu’i na wannan ɓangaren.

Peng Zhenghun et al. ya nuna cewa hanyoyi daban-daban na shirye-shiryen suna da babban tasiri akan aikin lantarki na kayan LiMn2O4 cathode. Ɗaukar Rct a matsayin misali: Rct na LiMn2O4 da aka haɗa ta hanyar babban zafin jiki mai ƙarfi yana da girma fiye da na hanyar sol-gel, kuma wannan al’amari bai shafi ions lithium ba. Hakanan ana nuna ma’aunin yaduwa. Dalilin shi ne cewa hanyoyi daban-daban na kira suna da babban tasiri akan crystallinity da ilimin halittar jiki na samfurori.

3. Low zazzabi halaye na cathode kayan na phosphate tsarin

Saboda kyakkyawan kwanciyar hankali da aminci, LiFePO4, tare da kayan ternary, ya zama babban jikin kayan cathode baturi na yanzu. Rashin ƙarancin zafin jiki na lithium baƙin ƙarfe phosphate ya fi yawa saboda kayansa da kansa shine insulator, tare da ƙarancin ƙarfin lantarki, ƙarancin ƙarancin lithium ion diffusivity, da rashin ƙarfi a cikin ƙananan zafin jiki, wanda ke ƙara juriya na ciki na baturi, wanda ke da tasiri sosai. polarization, kuma ana hana cajin baturi da fitarwa. Sabili da haka, Ayyukan ƙananan zafin jiki bai dace ba.

Lokacin nazarin halin caji-fitarwa na LiFePO4 a ƙananan zafin jiki, Gu Yijie et al. ya gano cewa ingancinsa na coulombic ya ragu daga 100% a 55°C zuwa 96% a 0°C da 64% a -20°C, bi da bi; karfin fitarwa ya ragu daga 3.11V a 55°C. Rage zuwa 2.62V a -20 ° C.

Xing et al. gyara LiFePO4 tare da nanocarbon kuma ya gano cewa bayan ƙara nanocarbon conductive wakili, aikin electrochemical na LiFePO4 bai kasance mai kula da zafin jiki ba, kuma an inganta ƙananan zafin jiki; ƙarfin fitarwa na LiFePO4 da aka gyara ya karu daga 3.40 a 25 °CV ya ragu zuwa 3.09V a -25 ° C, raguwa na 9.12% kawai; kuma ingancin tantanin halitta a -25 ° C shine 57.3%, wanda ya fi 53.4% ​​ba tare da wakili na nano-carbon ba.

Kwanan nan, LiMnPO4 ya jawo sha’awa mai yawa. Binciken ya gano cewa LiMnPO4 yana da fa’idodi na babban yuwuwar (4.1V), babu gurɓatacce, ƙarancin farashi, da takamaiman iya aiki (170mAh/g). Duk da haka, saboda ƙananan halayen ionic na LiMnPO4 fiye da LiFePO4, ana amfani da Fe sau da yawa don maye gurbin Mn don samar da ingantaccen bayani na LiMn0.8Fe0.2PO4 a aikace.

Low zazzabi Properties na anode kayan don lithium ion baturi

Idan aka kwatanta da ingantacciyar kayan lantarki, ƙarancin zafin ƙarancin kayan lantarki mara kyau na baturin lithium ion ya fi tsanani, galibi saboda dalilai uku masu zuwa:

Lokacin caji da fitarwa a cikin ƙananan zafin jiki da ƙimar girma, baturin yana da ƙarfi sosai, kuma babban adadin lithium na ƙarfe yana ajiya akan saman madaidaicin lantarki, kuma samfurin amsawar lithium na ƙarfe da electrolyte gabaɗaya ba shi da conductivity;

Daga ra’ayi na thermodynamic, electrolyte ya ƙunshi babban adadin ƙungiyoyin polar irin su CO da CN, wanda zai iya amsawa tare da kayan lantarki mara kyau, kuma fim din SEI da aka kafa ya fi sauƙi ga ƙananan zafin jiki;

The carbon negative electrode yana da wahala a haɗa lithium a ƙananan zafin jiki, kuma akwai cajin asymmetric da fitarwa.

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Bincike akan Ƙananan Zazzabi Electrolyte

Electrolyte yana taka rawa wajen jigilar Li + a cikin batir lithium-ion, kuma halayensa na ionic da abubuwan samar da fina-finai na SEI suna da tasiri mai mahimmanci akan ƙarancin yanayin zafi na baturi. Akwai manyan alamomi guda uku don yin hukunci akan ribobi da fursunoni na ƙananan zafin jiki na electrolytes: ionic conductivity, electrochemical taga da electrode reactivity. Matsayin waɗannan alamomi guda uku ya dogara da yawa akan kayan aikin sa: ƙarfi, electrolyte (gishirin lithium), da ƙari. Don haka, bincike kan ƙarancin zafin jiki na kowane ɓangare na electrolyte yana da mahimmanci ga fahimta da haɓaka ƙarancin zafin batirin.

Idan aka kwatanta da sarkar carbonates, ƙananan halayen zafin jiki na EC-based electrolytes, cyclic carbonates suna da ƙaƙƙarfan tsari, babban ƙarfin aiki, da mafi girma na narkewa da danko. Koyaya, babban polarity da tsarin zoben ya kawo ya sa sau da yawa yana da babban dielectric akai-akai. Babban dielectric akai-akai, high ionic conductivity, da kuma m film-forming Properties na EC kaushi yadda ya kamata hana co-saka da sauran ƙarfi kwayoyin, sa su zama makawa. Sabili da haka, yawancin tsarin lantarki masu ƙarancin zafin jiki da aka saba amfani da su suna dogara ne akan EC, sannan kuma gauraye Ƙananan ƙwayoyin ƙwayoyin cuta tare da ƙarancin narkewa.

Gishirin lithium shine muhimmin bangaren electrolyte. Lithium gishiri a cikin electrolyte ba zai iya kawai inganta ionic conductivity na maganin ba, amma kuma rage yaduwa nesa na Li + a cikin bayani. Gabaɗaya, mafi girman maida hankali na Li + a cikin maganin, mafi girman haɓakar ionic. Duk da haka, ƙaddamar da ions lithium a cikin electrolyte ba shi da alaƙa da haɗin gwiwar gishirin lithium, amma yana da alaƙa. Wannan shi ne saboda ƙaddamar da ions lithium a cikin sauran ƙarfi ya dogara da ƙarfin rarrabuwa da haɗin gwiwar gishirin lithium a cikin sauran ƙarfi.

Bincike akan Ƙananan Zazzabi Electrolyte

Baya ga abun da ke ciki na baturin da kansa, abubuwan sarrafawa a cikin ainihin aiki kuma za su yi tasiri sosai akan aikin baturin.
(1) Tsarin shiri. Yakubu et al. yayi nazari akan tasirin wutar lantarki da kauri akan ƙarancin zafin jiki na LiNi0.6Co0.2Mn0.2O2 / batir Graphite kuma ya gano cewa dangane da ƙarfin riƙewa, ƙaramin ƙarfin lantarki da ƙaramin abin rufewa, mafi kyawun ƙarancin ƙasa. aikin zafin jiki. .

(2) Yanayin caji da fitarwa. Petzl et al. yayi nazarin tasirin yanayin cajin-ƙananan zafin jiki akan rayuwar sake zagayowar baturi, kuma ya gano cewa lokacin da zurfin zurfafawar ya yi girma, zai haifar da asarar ƙarfin aiki da kuma rage rayuwar sake zagayowar.

(3) Wasu dalilai. Wurin da ke ƙasa, girman pore, ƙarancin wutar lantarki, ƙarancin wutar lantarki da lantarki, da mai rarrabawa, da dai sauransu, duk suna shafar ƙarancin yanayin zafi na batirin lithium-ion. Bugu da ƙari, tasirin kayan aiki da lahani na tsari akan ƙarancin zafin batirin ba za a iya watsi da shi ba.

takaita

Domin tabbatar da ƙarancin zafin batirin lithium-ion, ana buƙatar yin abubuwa masu zuwa:

(1) Samar da fim ɗin SEI na bakin ciki da yawa;

(2) Tabbatar cewa Li+ yana da babban adadin rarrabawa a cikin kayan aiki;

(3) Electrolyte yana da high ionic conductivity a low zazzabi.

Bugu da kari, binciken zai kuma iya nemo wata hanyar duba wata nau’in batirin lithium-ion baturi-dukkan-karfin batirin lithium-ion. Idan aka kwatanta da baturan lithium-ion na al’ada, ana sa ran batirin lithium-ion mai ƙarfi-dukkanin-jihar, musamman ma duk-ƙarfin-fim lithium-ion baturi, ana sa ran za su warware gaba ɗaya matsalar lalata iya aiki da amincin zagayowar lokacin da ake amfani da batura a ƙananan yanayin zafi. c