Nyob rau hauv qhov kub thiab txias ib puag ncig, lithium-ion roj teeb kev ua tau zoo tsis zoo tagnrho.Thaum siv cov roj teeb lithium-ion feem ntau ua haujlwm ntawm -10 ° C, lawv cov nqi siab tshaj plaws thiab lub peev xwm tawm thiab lub davhlau ya nyob twg qhov hluav taws xob yuav txo qis dua piv nrog qhov kub thiab txias [6], thaum qhov kub thiab txias poob mus rau -20 ° C, muaj peev xwm yuav. Txawm tias yuav txo qis rau 1/3 ntawm chav tsev kub 25 ° C, thaum qhov kub ntawm qhov paug tawm qis dua, qee cov roj teeb lithium tsis tuaj yeem txawm tias them thiab tso tawm cov dej num, nkag mus rau "tuag roj teeb" lub xeev.
1, Cov yam ntxwv ntawm lithium-ion roj teeb ntawm qhov kub thiab txias
(1) Macroscopic
Cov yam ntxwv hloov pauv ntawm lithium-ion roj teeb ntawm qhov kub thiab txias yog raws li hauv qab no: nrog rau qhov kub thiab txias tsis tu ncua, ohmic tsis kam thiab polarization tsis kam nce ntau degrees;Qhov hluav taws xob tawm ntawm lithium-ion roj teeb qis dua li qhov kub thiab txias.Thaum them thiab tso tawm ntawm qhov kub thiab txias, nws cov kev khiav hauj lwm voltage nce los yog poob sai dua li ntawm qhov kub thiab txias, ua rau muaj qhov txo qis hauv nws qhov siab tshaj plaws thiab lub zog siv tau.
(2) Microscopically
Kev hloov pauv ntawm cov roj teeb lithium-ion ntawm qhov kub thiab txias feem ntau yog vim muaj cov yam ntxwv tseem ceeb hauv qab no.Thaum lub ambient kub qis dua -20 ℃, cov kua electrolyte solidifies, nws viscosity nce sharply, thiab nws ionic conductivity txo.Lithium ion diffusion hauv cov khoom zoo thiab tsis zoo electrode yog qeeb;Lithium ion tsis yooj yim rau desolvate, thiab nws kis tau tus mob hauv SEI zaj duab xis qeeb, thiab tus nqi hloov pauv impedance nce.Qhov teeb meem lithium dendrite yog qhov tshwj xeeb tshaj yog nyob rau qhov kub thiab txias.
2, Txhawm rau daws qhov kev ua haujlwm kub ntawm cov roj ntsha lithium-ion
Tsim ib qho tshiab electrolytic kua system kom tau raws li qhov kub thiab txias ib puag ncig;Txhim kho qhov zoo thiab tsis zoo electrode qauv kom ceev cov kis tau tus mob ceev thiab txo qhov kis tau tus mob;Tswj cov khoom zoo thiab tsis zoo electrolyte interface kom txo impedance.
(1) electrolyte additives
Feem ntau, kev siv cov khoom siv ntxiv yog ib txoj hauv kev zoo tshaj plaws thiab kev siv nyiaj txiag los txhim kho qhov ntsuas kub ntawm cov roj teeb thiab pab tsim cov yeeb yaj kiab zoo tshaj plaws SEI.Tam sim no, lub ntsiab hom additives yog isocyanate raws li additives, sulfur raws li additives, ionic kua additives thiab inorganic lithium ntsev additives.
Piv txwv li, dimethyl sulfite (DMS) sulfur raws li additives, nrog rau qhov tsim nyog txo kev ua si, thiab vim hais tias nws txo cov khoom thiab lithium ion binding yog tsis muaj zog tshaj vinyl sulfate (DTD), alleviating siv cov organic additives yuav ua rau kom lub interface impedance, los tsim ib tug vinyl sulfate. ruaj khov thiab zoo dua ionic conductivity ntawm qhov tsis zoo electrode interface zaj duab xis.Cov sulfite esters sawv cev los ntawm dimethyl sulfite (DMS) muaj siab dielectric tas li thiab dav kev khiav hauj lwm kub ntau yam.
(2) Qhov hnyav ntawm electrolyte
Cov tshuaj lithium-ion roj teeb electrolyte yog kom yaj 1 mol ntawm lithium hexafluorophosphate (LiPF6) rau hauv cov kuab tshuaj sib xyaw, xws li EC, PC, VC, DMC, methyl ethyl carbonate (EMC) lossis diethyl carbonate (DEC), qhov twg muaj pes tsawg leeg. Qhov hnyav, melting point, dielectric tas li, viscosity thiab compatibility nrog lithium ntsev yuav cuam tshuam rau kev khiav hauj lwm kub ntawm lub roj teeb.Tam sim no, cov khoom lag luam electrolyte yog ib qho yooj yim rau solidify thaum siv rau qhov kub thiab txias ib puag ncig ntawm -20 ℃ thiab hauv qab no, qhov qis dielectric tas li ua rau lithium ntsev nyuaj rau dissociate, thiab lub viscosity siab dhau los ua rau lub roj teeb sab hauv thiab qis. voltage platform.Cov roj teeb lithium-ion tuaj yeem muaj qhov ua tau zoo ntawm qhov kub thiab txias los ntawm kev ua kom zoo dua qhov sib piv cov kuab tshuaj uas twb muaj lawm, xws li los ntawm kev ua kom zoo ntawm cov qauv electrolyte (EC: PC: EMC = 1: 2: 7) kom TiO2 (B) / graphene tsis zoo electrode muaj A. muaj peev xwm ntawm ~ 240 mA h g-1 ntawm -20 ℃ thiab 0.1 A g-1 tam sim no ntom.Los yog tsim cov kuab tshuaj uas tsis tshua muaj kub electrolyte tshiab.Kev ua haujlwm tsis zoo ntawm cov roj teeb lithium-ion ntawm qhov kub thiab txias yog feem ntau cuam tshuam nrog qeeb desolvation ntawm Li + thaum txheej txheem ntawm Li + embedding hauv cov khoom siv electrode.Cov khoom uas tsis tshua muaj zog ntawm Li + thiab cov kuab tshuaj molecules, xws li 1, 3-dioxopentylene (DIOX), tuaj yeem xaiv, thiab nanoscale lithium titanate yog siv los ua cov khoom siv electrode los sib sau cov roj teeb ntsuas kom them rau qhov txo qis diffusion coefficient ntawm cov khoom siv electrode ntawm ultra-tsawg kub, thiaj li ua tau zoo dua qhov kub thiab txias.
(3) lithium ntsev
Tam sim no, kev lag luam LiPF6 ion muaj kev ua haujlwm siab, cov dej noo siab hauv ib puag ncig, tsis zoo thermal stability, thiab cov pa phem xws li HF hauv cov tshuaj tiv thaiv dej yog ib qho yooj yim ua rau muaj kev nyab xeeb.Cov khoom siv electrolyte zaj duab xis tsim los ntawm lithium difluoroxalate borate (LiODFB) yog qhov ruaj khov txaus thiab muaj qhov ua tau zoo ntawm qhov kub thiab txias thiab kev ua haujlwm siab dua.Qhov no yog vim LiODFB muaj qhov zoo ntawm ob qho tib si lithium dioxalate borate (LiBOB) thiab LiBF4.
3. Cov ntsiab lus
Qhov ntsuas kub qis ntawm lithium-ion roj teeb yuav raug cuam tshuam los ntawm ntau yam xws li cov khoom siv hluav taws xob thiab cov electrolytes.Kev txhim kho los ntawm ntau qhov kev xav xws li cov khoom siv hluav taws xob thiab cov khoom siv hluav taws xob tuaj yeem txhawb kev siv thiab kev tsim cov roj teeb lithium-ion, thiab daim ntawv thov kev cia siab ntawm cov roj teeb lithium yog qhov zoo, tab sis cov thev naus laus zis yuav tsum tau tsim thiab ua tiav hauv kev tshawb fawb ntxiv.
Post lub sij hawm: Lub Xya hli ntuj-27-2023