Me yasa baturin iron phosphate na lithium ya gaza?

Fahimtar sanadi ko tsarin gazawar batirin lithium iron phosphate yana da matukar mahimmanci don inganta aikin batir da yawan samarwa da amfani da shi. Wannan labarin yana tattauna illolin ƙazanta, hanyoyin ƙirƙira, yanayin ajiya, sake yin amfani da su, ƙarin caji, da yawan zubar da ruwa akan gazawar baturi.

1. Rashin gazawa a cikin tsarin samarwa

A cikin tsarin samarwa, ma'aikata, kayan aiki, albarkatun ƙasa, hanyoyi, da muhalli sune manyan abubuwan da ke shafar ingancin samfurin. A cikin tsarin samar da batirin wutar lantarki na LiFePO4, ma'aikata da kayan aiki suna cikin iyakokin gudanarwa, don haka muna tattauna batutuwan sakamako uku na ƙarshe.

Rashin ƙazanta a cikin kayan lantarki mai aiki yana haifar da gazawar baturi.

A lokacin haɗin LiFePO4, za a sami ƙaramin adadin ƙazanta kamar Fe2O3 da Fe. Wadannan ƙazanta za a rage su a saman gurɓataccen lantarki kuma suna iya huda diaphragm kuma su haifar da gajeren da'ira na ciki. Lokacin da aka fallasa LiFePO4 zuwa iska na dogon lokaci, danshi zai lalata baturin. A farkon mataki na tsufa, amorphous iron phosphate an kafa a saman kayan. Abubuwan da ke cikin gida da tsarin sa suna kama da LiFePO4 (OH); tare da shigar da OH, LiFePO4 yana ci gaba da cinyewa, An bayyana shi azaman karuwa a girma; daga baya aka sake recrystallized a hankali don samar da LiFePO4(OH). Rashin ƙazantar Li3PO4 a cikin LiFePO4 ba ta da ƙarfin lantarki. Mafi girman abun ciki na ƙazanta na graphite anode, mafi girman asarar ƙarfin da ba za a iya jurewa ba.

Rashin gazawar baturin ya haifar da hanyar samuwar

Asarar ion lithium mai aiki da ba za a iya jurewa ba ana fara nunawa a cikin ion lithium da ake cinyewa yayin da suke samar da ingantaccen membrane interfacial membrane. Nazarin ya gano cewa ƙara yawan zafin jiki na samuwar zai haifar da asarar ion lithium da ba za a iya jurewa ba. Lokacin da yawan zafin jiki na samuwar ya karu, adadin abubuwan da ba su da lafiya a cikin fim din SEI zai karu. Gas ɗin da aka saki a lokacin canji daga sashin kwayoyin halitta ROCO2Li zuwa sashin inorganic Li2CO3 zai haifar da ƙarin lahani a cikin fim ɗin SEI. Yawancin ions lithium da aka warware ta waɗannan lahani za a saka su a cikin madaidaicin graphite lantarki.

A lokacin da aka samu, abun da ke ciki da kauri na fim din SEI da aka kafa ta hanyar ƙananan cajin da ake yi a halin yanzu suna da daidaituwa amma suna cin lokaci; Babban caji na yau da kullun zai haifar da ƙarin halayen gefe don faruwa, yana haifar da ƙarar asarar lithium-ion da ba za a iya jurewa ba kuma ƙarancin ƙirar lantarki mara kyau shima zai karu, amma yana adana lokaci. Lokaci; A zamanin yau, ana amfani da yanayin samar da ƙananan na yau da kullun na yau da kullun-manyan ƙarfin yau da kullun na yau da kullun da ƙarfin lantarki akai-akai ta yadda zai iya ɗaukar fa'idodin duka biyun cikin lissafi.

Rashin batir ya haifar da danshi a cikin yanayin samarwa

A zahirin samarwa, batirin ba makawa zai tuntuɓar iska saboda abubuwa masu kyau da marasa kyau galibi ƙananan ƙwayoyin micron ne ko nano masu girman gaske, kuma ƙwayoyin ƙarfi a cikin electrolyte suna da ƙungiyoyin carbonyl masu ƙarfi na electronegative da ƙungiyoyin carbon-carbon biyu masu daidaitawa. Duk sauƙin sha danshi a cikin iska.

Kwayoyin ruwa suna amsawa tare da gishiri lithium (musamman LiPF6) a cikin electrolyte, wanda ke lalatawa kuma yana cinye electrolyte (bazuwa ya zama PF5) kuma yana samar da sinadarin acidic HF. Dukansu PF5 da HF za su lalata fim ɗin SEI, kuma HF kuma za ta inganta lalata kayan aiki na LiFePO4. Kwayoyin ruwa kuma za su lalata wutar lantarki mara kyau na lithium-intercalated graphite, suna samar da lithium hydroxide a kasan fim ɗin SEI. Bugu da kari, O2 narkar da a cikin electrolyte zai kuma hanzarta tsufa na LiFePO4 baturi.

A cikin tsarin samarwa, baya ga tsarin samarwa wanda ke shafar aikin baturi, manyan abubuwan da ke haifar da gazawar batirin wutar lantarki na LiFePO4 sun haɗa da najasa a cikin albarkatun ƙasa (ciki har da ruwa) da tsarin samuwar, don haka tsaftataccen ruwa. abu, kula da yanayin zafi, hanyar samuwar, da dai sauransu Abubuwan da ke da mahimmanci.

2. Kasawa a cikin tanadi

Yayin rayuwar sabis na baturin wuta, yawancin lokacinsa yana cikin yanayin tanadi. Gabaɗaya, bayan dogon lokacin ajiya, aikin baturi zai ragu, yawanci yana nuna haɓaka juriya na ciki, raguwar ƙarfin lantarki, da raguwar ƙarfin fitarwa. Abubuwa da yawa suna haifar da lalacewar aikin baturi, wanda zafin jiki, yanayin caji, da lokaci sune abubuwan da suka fi bayyana tasiri.

Kasem et al. yayi nazarin tsufa na batirin wutar lantarki na LiFePO4 a ƙarƙashin yanayin ajiya daban-daban. Sun yi imani da cewa tsarin tsufa shine mafi yawan halayen halayen halayen lantarki masu kyau da marasa kyau. A electrolyte (idan aka kwatanta da gefen dauki na tabbatacce lantarki, da gefen dauki na korau graphite lantarki ne nauyi, yafi lalacewa ta hanyar sauran ƙarfi. Bazuwa, da girma na SEI film) cinye aiki lithium ions. A lokaci guda, jimlar impedance na baturi yana ƙaruwa, asarar ion lithium mai aiki yana haifar da tsufa lokacin da baturi ya bar shi. Rashin iya aiki na batirin wutar lantarki na LiFePO4 yana ƙaruwa tare da hawan zafin jiki na ajiya. Sabanin haka, yayin da yanayin cajin ajiya ya karu, asarar iya aiki ya fi ƙanƙanta.

Grolleau et al. Har ila yau, ya kai ga ƙarshe: yawan zafin jiki na ajiya yana da tasiri mai mahimmanci akan tsufa na baturan wutar lantarki na LiFePO4, sannan kuma yanayin cajin ajiya ya biyo baya, kuma ana ba da shawarar samfurin sauƙi. Zai iya hango hasarar iya aiki na baturin wutar lantarki na LiFePO4 dangane da abubuwan da suka shafi lokacin ajiya (zazzabi da yanayin caji). A cikin wani takamaiman yanayin SOC, yayin da lokacin shiryayye ya ƙaru, lithium a cikin graphite zai yaɗu zuwa gefen, yana samar da hadadden fili tare da electrolyte da electrons, wanda ke haifar da haɓakar adadin ions lithium wanda ba zai iya jurewa ba, kauri na SEI, da kuma conductivity. Ƙaruwar rashin ƙarfi da ke haifar da raguwa (inorganic abubuwan haɓaka suna ƙaruwa, wasu kuma suna da damar sake narkar da su) da kuma raguwar aikin saman lantarki tare yana haifar da tsufa na baturi.

Ko da halin da ake ciki na caji ko yanayin fitarwa, bambancin calorimetry na dubawa bai sami wani amsa ba tsakanin LiFePO4 da electrolytes daban-daban (electrolyte shine LiBF4, LiAsF6, ko LiPF6) a cikin kewayon zafin jiki daga zafin daki zuwa 85°C. Koyaya, lokacin da aka nutsar da LiFePO4 a cikin electrolyte na LiPF6 na dogon lokaci, har yanzu zai nuna takamaiman amsawa. Saboda amsawar da aka yi don samar da dubawa ya tsawaita, har yanzu babu fim ɗin wucewa a saman LiFePO4 don hana ƙarin amsawa tare da electrolyte bayan nutsewa na wata ɗaya.

A cikin shelving, yanayin ajiya mara kyau (babban zafin jiki da kuma babban yanayin caji) zai ƙara yawan zubar da kai na baturin wutar lantarki na LiFePO4, yana sa baturi ya tsufa a fili.

3. Kasawa a sake amfani da su

Batura gabaɗaya suna fitar da zafi yayin amfani, don haka tasirin zafin jiki yana da mahimmanci. Bugu da kari, yanayin hanya, amfani, da zafin yanayi duk zasu sami tasiri daban-daban.

Asarar ion lithium mai aiki gabaɗaya yana haifar da asarar ƙarfin batura masu ƙarfi na LiFePO4 yayin hawan keke. Dubari et al. ya nuna cewa tsufa na batirin wutar lantarki na LiFePO4 a lokacin hawan keke shine yafi saboda tsarin ci gaba mai rikitarwa wanda ke cinye aikin lithium-ion SEI fim. A cikin wannan tsari, asarar ions lithium mai aiki kai tsaye yana rage yawan riƙe ƙarfin baturi; ci gaba da ci gaba na fim din SEI, a gefe guda, yana haifar da karuwa a cikin juriya na polarization na baturi. A lokaci guda, kauri na fim ɗin SEI ya yi kauri sosai, da kuma aikin electrochemical na graphite anode. Zai kashe wani bangare na aikin.

A lokacin hawan keke mai zafi, Fe2+ a cikin LiFePO4 zai narke zuwa wani matsayi. Ko da yake adadin Fe2 + narkar da ba shi da wani gagarumin tasiri a kan iya aiki na m lantarki, da rushe Fe2 + da hazo na Fe a kan korau graphite lantarki zai taka catalytic rawa a ci gaban da SEI fim. . Tan kididdigar inda da kuma inda aka rasa ions lithium masu aiki kuma an gano cewa yawancin asarar ions na lithium masu aiki sun faru ne a saman madaidaicin graphite electrode, musamman a lokacin hawan zafi mai zafi, wato, asarar ƙarfin sake zagayowar yanayi mai zafi. yana da sauri, kuma ya taƙaita fim ɗin SEI Akwai hanyoyi daban-daban na lalacewa da gyarawa:

1. Electrons a cikin graphite anode suna wucewa ta cikin fim ɗin SEI don rage ions lithium.
2. Rushewa da sabuntawa na wasu sassa na fim din SEI.
3. Saboda canjin girma na graphite anode, membrane SEI ya haifar da fashewa.

Baya ga asarar ion lithium mai aiki, duka abubuwa masu kyau da marasa kyau zasu lalace yayin sake yin amfani da su. Abubuwan da suka faru na fashewa a cikin na'urar lantarki ta LiFePO4 yayin sake yin amfani da su zai sa polarization na lantarki ya karu da kuma tafiyar da aiki tsakanin kayan aiki da wakili mai gudanarwa ko mai tarawa na yanzu don ragewa. Nagpure yayi amfani da Scanning Extended Resistance Microscope (SSRM) don nazarin sauye-sauye na LiFePO4 bayan tsufa kuma ya gano cewa haɓakar LiFePO4 nanoparticles da adibas ɗin saman da aka samar ta takamaiman halayen sinadarai tare ya haifar da haɓaka haɓakar LiFePO4 cathodes. Bugu da kari, raguwar saman da ke aiki da kuma fitar da na'urorin lantarki na graphite da ke haifar da asarar kayan aikin graphite shima ana la'akari da su shine sanadin tsufa. Rashin kwanciyar hankali na graphite anode zai haifar da rashin kwanciyar hankali na fim din SEI kuma ya inganta amfani da ions lithium mai aiki.

Fitar da baturi mai girma zai iya ba da iko mai mahimmanci ga abin hawa na lantarki; wato mafi kyawun aikin baturin wutar lantarki, mafi kyawun aikin hanzari na motar lantarki. Sakamakon bincike na Kim et al. ya nuna cewa tsarin tsufa na LiFePO4 tabbataccen lantarki da graphite korau electrode ya bambanta: tare da haɓaka ƙimar fitarwa, asarar iya aiki na ingantacciyar wutar lantarki yana ƙaruwa fiye da na gurɓataccen lantarki. Asarar ƙarfin baturi yayin hawan keke mai ƙarancin ƙima ya samo asali ne saboda amfani da ion lithium mai aiki a cikin gurɓataccen lantarki. Sabanin haka, hasarar wutar lantarki na baturi yayin hawan keke mai girma yana faruwa ne saboda haɓakar rashin ƙarfi na ingantaccen lantarki.

Kodayake zurfin fitarwa na baturin wutar lantarki da ake amfani da shi ba zai shafi asarar iya aiki ba, zai shafi asarar wutar lantarki: saurin asarar wutar lantarki yana ƙaruwa tare da karuwar zurfin fitarwa. Wannan ya faru ne saboda tashin hankali na fim din SEI da karuwa a cikin karfin baturi duka. Yana da alaƙa kai tsaye. Kodayake dangane da asarar ions lithium mai aiki, babban iyaka na cajin wutar lantarki ba shi da wani tasiri mai tasiri akan gazawar baturi, ƙarancin ƙarancin ƙarfin ƙarfin cajin ko babba zai ƙara haɓakar keɓantawar na'urar lantarki ta LiFePO4: ƙaramin babba babba. iyaka ƙarfin lantarki ba zai yi aiki da kyau ba. An kafa fim ɗin wucewa a ƙasa, kuma iyakar ƙarfin lantarki mai girma da yawa zai haifar da lalatawar oxidative na electrolyte. Zai ƙirƙiri samfur tare da ƙarancin ɗawainiya akan saman na'urar lantarki ta LiFePO4.

Ƙarfin fitarwa na baturin wutar lantarki na LiFePO4 zai ragu da sauri lokacin da zafin jiki ya ragu, musamman saboda raguwar ion conductivity da karuwar rashin daidaituwa. Li ya yi nazarin LiFePO4 cathode da graphite anode daban kuma ya gano cewa manyan abubuwan sarrafawa waɗanda ke iyakance ƙarancin yanayin zafi na anode da anode sun bambanta. Ragewar ionic conductivity na LiFePO4 cathode yana da rinjaye, kuma karuwa a cikin haɗin kai na graphite anode shine babban dalili.

A lokacin amfani, lalatawar LiFePO4 electrode da graphite anode da ci gaba da girma na fim din SEI zai haifar da gazawar baturi zuwa digiri daban-daban. Bugu da ƙari, ban da abubuwan da ba za a iya sarrafawa ba kamar yanayin hanya da zafin jiki na yanayi, yin amfani da baturi na yau da kullum yana da mahimmanci, ciki har da ƙarfin caji mai dacewa, zurfin da ya dace na fitarwa, da dai sauransu.

4. gazawa yayin caji da fitarwa

Sau da yawa babu makawa ana yin cajin baturi yayin amfani. Akwai ƙarancin zubar da ruwa. Zafin da ake fitarwa yayin cajin da ya wuce kima ko yawan fitar da ruwa mai yuwuwa ya taru a cikin baturin, yana ƙara yawan zafin baturin. Yana shafar rayuwar sabis ɗin baturi kuma yana ɗaga yuwuwar wuta ko fashewar guguwa. Ko da a ƙarƙashin yanayin caji da caji na yau da kullun, yayin da adadin hawan ke ƙaruwa, rashin daidaituwar ƙarfin sel guda a cikin tsarin baturi zai ƙaru. Baturin tare da mafi ƙarancin ƙarfi zai yi aikin caji da wuce gona da iri.

Ko da yake LiFePO4 yana da mafi kyawun kwanciyar hankali na zafi idan aka kwatanta da sauran ingantattun kayan lantarki a ƙarƙashin yanayin caji daban-daban, fiye da kima na iya haifar da haɗari mara aminci a cikin amfani da batura masu ƙarfi na LiFePO4. A cikin yanayin da ya wuce kima, kaushi a cikin kwayoyin halitta na lantarki ya fi dacewa da Rushewar Oxidative. Daga cikin abubuwan da aka saba amfani da su na kaushi, ethylene carbonate (EC) zai fi dacewa ya sha bazuwar oxidative a saman ingantaccen lantarki. Tunda yuwuwar shigar lithium (tare da yuwuwar lithium) na lantarki graphite mara kyau ba shi da zurfi, hazo lithium yana da yuwuwa a cikin madaidaicin graphite lantarki.

Ɗaya daga cikin manyan dalilan gazawar baturi a ƙarƙashin ƙarin cajin yanayi shine gajeriyar da'ira ta ciki wanda rassan lithium crystal suka huda diaphragm. Lu et al. yayi nazari akan tsarin gazawar lithium plating akan graphite mai adawa da farfajiyar lantarki wanda ya haifar da ƙarin caji. Sakamakon ya nuna cewa tsarin gabaɗaya na lantarki na graphite mara kyau bai canza ba, amma akwai rassan lithium crystal da fim ɗin saman. Halin lithium da electrolyte yana sa fim ɗin saman ya karu ci gaba, wanda ke cinye mafi yawan lithium kuma yana haifar da lithium don yaduwa cikin graphite. Wutar lantarki mara kyau ta zama mai rikitarwa, wanda zai ƙara haɓaka ƙaddamar da lithium a saman ƙarancin lantarki, yana haifar da ƙarin raguwa a cikin iya aiki da ingantaccen coulombic.

Bugu da kari, dattin ƙarfe (musamman Fe) ana ɗaukarsa ɗaya daga cikin manyan dalilan gazawar cajin baturi. Xu et al. yayi nazari akai-akai akan tsarin gazawar batirin wutar lantarki na LiFePO4 a ƙarƙashin yanayin caji. Sakamakon ya nuna cewa redox na Fe a lokacin zagayowar overcharge/zarge yana yiwuwa a ka'ida, kuma ana ba da tsarin amsawa. Lokacin da ƙarin cajin ya faru, Fe zai fara oxidized zuwa Fe2+, Fe2+ yana ƙara lalacewa zuwa Fe3+, sannan Fe2+ da Fe3+ ana cire su daga ingantaccen lantarki. Ɗayan gefe yana bazuwa zuwa gefen wutar lantarki mara kyau, Fe3 + an rage shi zuwa Fe2+, kuma Fe2+ yana kara ragewa zuwa Fe; a lokacin da overcharge / sauke hawan keke, Fe crystal rassan za su fara a tabbatacce da kuma korau electrodes a lokaci guda, sokin da SEPARATOR ya haifar da Fe gadoji, sakamakon micro baturi Short kewaye, da fili sabon abu cewa raka baturi ta micro short circuit ne m. ƙara yawan zafin jiki bayan caji.

A lokacin cajin da yawa, yuwuwar gurɓataccen lantarki zai tashi da sauri. Ƙarfafawar haɓakawa zai lalata fim ɗin SEI akan farfajiyar wutar lantarki mara kyau (ɓangaren da ke da wadata a cikin mahaɗan inorganic a cikin fim ɗin SEI zai iya zama oxidized), wanda zai haifar da ƙarin Rushewa na electrolyte, wanda zai haifar da asarar iya aiki. Mafi mahimmanci, mummunan mai tarawa Cu foil zai zama oxidized. A cikin fim din SEI na mummunan lantarki, Yang et al. gano Cu2O, samfurin hadawan abu da iskar shaka na Cu foil, wanda zai ƙara juriya na ciki na baturi kuma ya haifar da asarar ƙarfin guguwa.

Ya et al. yayi nazari dalla-dalla kan tsarin fitar da batir mai ƙarfi na LiFePO4 dalla-dalla. Sakamako ya nuna cewa za a iya sanya mai karɓar Cu foil mara kyau na yanzu zuwa Cu + yayin zubar da ruwa mai yawa, kuma Cu + yana ƙara oxidized zuwa Cu2+, bayan haka suna yaduwa zuwa ingantaccen lantarki. Wani ragi na iya faruwa a ingantaccen lantarki. Ta wannan hanyar, zai samar da rassan crystal a gefen ingantaccen lantarki, ya huda mai raba kuma ya haifar da ɗan gajeren da'ira a cikin baturi. Hakanan, saboda yawan zubar da ruwa, zafin baturi zai ci gaba da hauhawa.

Yawan cajin baturin wutar lantarki na LiFePO4 na iya haifar da bazuwar oxidative electrolyte, juyin halittar lithium, da samuwar rassan kristal Fe; over-fitarwa na iya haifar da lalacewa ta SEI, wanda ke haifar da lalacewar iya aiki, Cu foil oxidation, har ma da bayyanar Cu rassan crystal.

5. sauran kasawa

Saboda ƙarancin ƙaƙƙarfan ƙaƙƙarfan ƙaƙƙarfan ƙa'idar LiFePO4, ƙirar halittar jiki da girman kayan kanta da tasirin abubuwan gudanarwa da masu ɗaure suna bayyana cikin sauƙi. Gaberscek et al. sun tattauna abubuwa biyu masu cin karo da juna na girman da murfin carbon kuma sun gano cewa impedance electrode na LiFePO4 yana da alaƙa ne kawai da matsakaicin girman ƙwayar. Lalacewar anti-site a LiFePO4 (Fe occupies Li sites) zai yi tasiri na musamman akan aikin baturi: saboda watsa ions lithium a cikin LiFePO4 yana da girma ɗaya, wannan lahani zai hana sadarwar lithium ions; saboda gabatarwar manyan jihohin valence Saboda ƙarin ƙin wutar lantarki, wannan lahani kuma na iya haifar da rashin kwanciyar hankali na tsarin LiFePO4.

Manyan barbashi na LiFePO4 ba za su iya jin daɗi gaba ɗaya a ƙarshen caji ba; Nano-tsaran LiFePO4 na iya rage lahani na jujjuyawar, amma babban ƙarfinsa zai haifar da fitar da kai. PVDF shine abin ɗaure da aka fi amfani dashi a halin yanzu, wanda ke da rashin lahani kamar amsawa a babban zafin jiki, narkar da wutar lantarki mara ruwa, da rashin isasshen sassauci. Yana da tasiri na musamman akan asarar iya aiki da rayuwar sake zagayowar LiFePO4. Bugu da ƙari, mai tarawa na yanzu, diaphragm, abun da ke cikin electrolyte, tsarin samarwa, abubuwan ɗan adam, girgizar waje, girgiza, da dai sauransu, za su shafi aikin baturi zuwa digiri daban-daban.

Magana: Miao Meng et al. "Ci gaban Bincike kan Rashin Baturan Ƙarfin Ƙarfin Lithium Iron Phosphate."