Yintoni iNdlela yokuthotywa koMmandla weBetri?
Utshintsho kuLwakhiwo Lwezinto
Izixhobo ze-cathode ezisetyenziswa ngoku kakhulu ziquka i-hexagonal layered structure ye-LiMO2 (apho M=Co, Ni, Mn), isakhiwo se-spinel se-LiMn2O4, kunye nesakhiwo se-olivine se-LiFePO4. Kungakhathaliseki ukuba yintoni na isakhiwo, xa i-lithium ion deintercalate ukusuka kwi-cathode, ukugcina imeko yombane kwizinto eziphathekayo, i-metal element i-oxidized ngokuqinisekileyo kwi-valence state ephezulu, ehamba kunye nenkqubo yokuguqulwa kwesigaba. Utshintsho lwesigaba luhlala lukhokelela ekutshintsheni kwesigaba, ngoko ke njengoko i-lithium ion iqhubeka idibanisa kwaye idibanisa kwizinto eziphathekayo, utshintsho lwesigaba luyaqhubeka, kwaye ekuhambeni kwexesha luya kubangela ingozi kwi-crystal stability. Xa kuthelekiswa ne-anode, umthamo ongalinganiyo oguqulwayo obangelwa ukutshintshwa kwesigaba kunye noshintsho kwisakhiwo sobuninzi bezinto ze-cathode zinempembelelo enkulu kubomi bebhetri. Igraphite inesakhiwo esimaleko. Xa imigangatho emininzi, i-lithium ion idibanisa kwi-interlayers ngexesha lokutshaja kwebhetri kwaye idibanise nee-electron ezithuthwa kwisekethe yangaphandle ukuze zenze i-lithiated graphite, kwaye i-interlayer spacing iyanda ngeli xesha; ngexesha lokukhutshwa, i-lithium ion ishiya i-graphite interlayers kwaye ikhulule ii-electron kwisiphaluka sangaphandle, iqhutywe kwi-deintercalation kunye ne-oxidation reaction, kwaye i-interlayer spacing iyancipha ngeli xesha.
Ukupheliswa kwezinto ezisebenzayo
Ukuchithwa kwezinto ze-cathode kubhekisela kwinkqubo apho izinto ezisebenzayo ziyancipha ngokuthe ngcembe ngenxa yokubola kwi-electrolyte. Ukutshatyalaliswa kwezinto ze-cathode kumaqondo aphezulu obushushu sesinye sezizathu zokubola kwamandla ebhetri, ngokukodwa ukuba nefuthe elikhulu ekusebenzeni komjikelo kunye nokusebenza kokugcinwa kweebhetri kumaqondo aphezulu. Ukutshatyalaliswa kweentsimbi zenguqu phantsi kweemeko ezithile yingxaki ekhoyo kuzo zonke izinto ze-cathode ze-LiMO2. Izizathu eziphambili zokuba kutheni ukuchithwa kwezinto ezisebenzayo kukhokelela ekudakaleni kokusebenza kwebhetri zezi: $\\textcircled{1}$ Ukuchithwa kwezinto zetsimbi kukhokelela ngokuthe ngqo ekunciphiseni izinto ezisebenzayo, ezibangela ukulahlekelwa kwamandla ebhetri; $\\textcircled{2}$ Ukutshatyalaliswa kwezinto ze-cathode kubangela ukuthotywa kwesakhiwo sezinto eziphathekayo kunye nokwakhiwa kwezinto ezingasebenzi ngamakhemikhali ebusweni beengqungquthela, ezithintela ukuthuthwa kwe-lithium ion kwi-electrode material; $\\textcircled{3}$ I-ion zensimbi ezinyibilikisiweyo eziqulethwe kwi-electrolyte zifudukela kwi-anode kwi-electrolyte kwaye zifake kwi-anode surface ngendlela yesinyithi okanye ityuwa ephantsi kwamandla aphantsi, kwaye ezi diphozithi zichaphazela ngokuqinisekileyo ukuzinza kunye nobukhulu befilimu ye-SEI kwindawo ye-anode, ekhokelela ekwandeni kwe-electrode surface polarization kunye nokwanda kokuchasana kwebhetri kwangaphakathi. Ngoko ke, umphumo wokuchithwa kwezinto ezisebenzayo kwi-electrolyte akuveli kuphela ekuchithekeni kodwa nakwimiphumo emibi kakhulu ebangelwa ukuchithwa kweentsimbi zenguqu.
Ukusetyenziswa kweLithium ion
Kuyilo lweebhetri ze-lithium -ibhetri ye-ion, umthamo webhetri ngokuqhelekileyo ungaphezulu kancinane kune-cathode, kwaye i-ion ze-lithium ezinokuphinda zisetyenziswe zibonelelwa yi-cathode. Ke ngoko, ukuhlangana okubuyiselwa umva kunye nokudityaniswa kwe-ion ze-lithium phakathi kwe-cathode kunye ne-anode kumisela umthamo webhetri. Ngethuba lokuqala lokuhlawuliswa kunye nenkqubo yokukhupha, ifilimu ye-SEI yenziwa kwindawo ye-anode. Amacandelo aphambili ale filimu yokupasa zizinto ezahlukeneyo ze-inorganic ezifana ne-Li2CO3, i-LiF, i-Li2O, i-LiOH kunye nezinto ezahlukeneyo zezinto eziphilayo ezifana ne-ROCO2Li, i-ROLi, kunye ne- (ROCO2) 2Li. Ke, ezinye ii-ion ze-lithium ziyatyiwa, kwaye le lahleko yomthamo ayinakuguqulwa. Ukusebenza kwe-anode kunxulumene kakhulu ne-morphology kunye nokuzinza kwefilimu ye-SEI, kunye nokukwazi ukwenza ifilimu ye-SEI ezinzileyo kumphezulu we-anode unempembelelo engathandabuzekiyo ekusebenzeni kwebhetri. Ukuqulunqwa kwefilimu ye-SEI kudla i-lithium ion elinganiselwe kwibhetri. Ukuba ifilimu ye-SEI yonakaliswa ngokuqhubekayo ngexesha lomjikelo, ngoko ukusabela kwe-oxidation kwi-anode / electrolyte interface kuya kwenzeka ngokuqhubekayo ukwenza ifilimu entsha ye-SEI. Le nkqubo idla i-lithium ion elinganiselweyo enikezelwa yi-cathode kwinkqubo, kunye nokunciphisa i-lithium ion esebenzayo kukhokelela ekuboleni kwamandla. Ukunciphisa i-lithium ion kwi-electrolyte kukhokelela ekunciphiseni kwe-conductivity ye-electrolyte, kwaye ukulahlekelwa kwe-lithium ion kwizinto ze-cathode kubangela ukungalingani phakathi kwee-electrodes ezimbini zebhetri.
Ukonyuka koKuchasa Ngaphakathi
Ngexesha elide-lokuhamba ngebhayisikile kwebhetri, ukonyuka kokunganyangeki kwangaphakathi sisizathu esibalulekileyo sokubola komthamo. Zininzi izizathu zokonyuka kokuchasana kwangaphakathi, ikakhulu kwimiba emibini: $\\textcircled{1}$ Ukusabela kwe-oxidation okwenzeka kwi-electrode/electrolyte interface kwi-electrolyte kukhokelela ekonyukeni kokumelana nefilimu yomphezulu we-electrode, kunye nokungazinzi kwefilimu ye-anode SEI, isenza ngokuqhubekayo iifilimu ezintsha zomhlaba ngexesha lomjikelo, ukuxhathisa kwebhetri, njl njl. $\\textcircled{2}$ Ukutshatyalaliswa kwee-ion zetsimbi kwi-cathode kwi-electrolyte, kunye ne-ionized metal ionized ion zifudukela kwi-anode ngokusebenzisa i-electrolyte kunye ne-deposit kwi-anode surface ngendlela yesinyithi okanye ityuwa, okubangela ukunyuka kwe-electrode polarization. Ukongezelela, uphando luye lwabonisa ukuba ukubola komqokeleli wangoku kunokukhokelela ekwandeni kokuchasana kwangaphakathi, kodwa esi siphumo sincinci phantsi kwesiseko sonyango lwangaphambili lomqokeleli wangoku. Ukunyuka kokuchasana kwangaphakathi kukhokelela ekunciphiseni ubuninzi bamandla kunye nomthamo, ngakumbi kwi-anode, ukusabela okwenzeka kwi-electrode / electrolyte interface sesona sizathu siphambili sokuguga kwe-anode.
