He aha ke ʻano hana ʻana o ka Battery?

He aha ke ʻano hana ʻana o ka Battery?

I kēia manawa, ʻaʻohe ʻike pololei a paʻa mau o ke ʻano hana electrochemical reaction o LiFePO₄ ma ka ʻoihana. ʻO ka hoʻohana ʻana o ka anion composite (PO₄)³⁻ e hoʻolilo i ka hao -mea hoʻohui i mea moho kūpono no ka lithium-ion cathodes. Eia nō naʻe, ke kaupalena ʻia ka hana aniani o LiFePO₄ i kona conductivity a me ka lithium -ion diffusion performance, ka hopena i ka emi ʻana o ka hana electrochemical o ka mea. ʻAʻole like me nā mea i hoʻopaʻa ʻia, ʻo ka pihi hoʻokuʻu o LiMPO₄ maʻamau he pāpū palahalaha loa, ʻo ia ke ʻano maʻamau o ʻelua - hoʻololi ʻana, ʻo ia hoʻi, e hana ʻia kahi kaʻina hoʻololi ma waena o LiMPO₄ a me MPO₄ i ka wā o ka lithium -ion intercalation/deintercalation.

Loaʻa ka LiFePO4 i ʻelua -mekanika hoʻololi i ka wā o ka hoʻouka ʻana a me ka hoʻokuʻu ʻana i loko o kahi pākaukau, ʻo ia hoʻi.

Reaction mechanism model

I ka hoʻouka ʻana, neʻe ʻo Li⁺ mai ka papa FeO₆, hele i ka electrolyte, a komo i ka electrode ʻino. Hoʻokahe ʻia ʻo Fe²⁺ i Fe³⁺, ʻoiai e holo ana nā electrons mai ke kaapuni o waho a i ka electrode ʻino ma o ka mea hoʻopili conductive a me ka ʻohi o kēia manawa. ʻO ke kaʻina hana hoʻokuʻu ʻo ia ka hope.

No ka wehewehe ʻana i kēia -ʻano hana ʻelua, ʻo Padhi a me Goodenough et al. 'O ka mea mua i ho'opuka i ka "core-shell model," 'o ia ka mea e 'ike 'ia ana ke ka'ina hana intercalation/deintercalation lithium i ka LiFePO₄/FePO₄ elua-pili, e like me ka hoike ana ma ke Kii 4-3a.

I ka wā o ka hoʻouka ʻana, neʻe mau ka LiFePO₄/FePO₄ mai ka ʻili a i ke kikowaena, me ka neʻe ʻana i ke kumu. Holo mau ʻo Li⁺ i waho, a hoʻololi mau ka LiFePO₄ waho i FePO₄. Ke hele mau nei nā ion Lithium a me nā electrons ma waena o nā -ʻano hou i hana ʻia no ka mālama ʻana i ke au kūpono, akā, ʻo ka litium{3}}ion diffusion rate paʻa mau ma lalo o kekahi mau kūlana. Ke emi nei ka pilina ma waena o nā ʻāpana ʻelua, ʻaʻole lawa ka diffusion o nā ion lithium no ka mālama ʻana i kahi manawa kūpono. ʻAʻole e hoʻohana piha ʻia ka LiFePO₄ i loko o ke koʻo koʻikoʻi, e hopena i ka nalowale o ka hiki. Ma hope o ka pau ʻana o ka hoʻopaʻa ʻana, e noho ʻo LiFePO₄ i hoʻohana ʻole ʻia i waenakonu o ka ʻāpana.

Ke noʻonoʻo nei e hiki ke hoʻopili a hoʻokaʻawale i nā ion lithium i ka manawa like ma nā wahi he nui, Andersson et al. ua hoʻolālā ʻia ke kumu hoʻohālike mosaic e wehewehe i ka nalowale o ka mana mua, e like me ka hōʻike ʻana ma ke Kiʻi 4-3b. Ke kuhi nei ke kŘkohu mosaic, oiai aia ke kaʻina hana hoʻokaʻawale ʻana o ka lithium ion a me ke kaʻina deintercalation ma ka LiFePO₄/FePO₄ ʻelua -ʻaoʻao, hiki ke hana i kēlā me kēia wahi i loko o ka particle. I ka wā o ka hoʻouka ʻana, hoʻonui ka ʻāina FePO₄ ma nā wahi like ʻole ma ka ʻāpana, a ʻo nā ʻaoʻao o kēia mau ʻāpana e hoʻopili ʻia, e hana ana i nā ʻāpana make hiki ʻole ke hoʻokō ʻia, no laila e hoʻopau ai i ka hiki. I ka wā o ka hoʻokuʻu ʻana, hiki mai ka hopena hope, me nā ion lithium e hoʻopili ana i ka pae FePO₄. ʻO ka ʻāpana ma ke kumu kahi i hoʻopili ʻole ʻia nā ion lithium i hopena i ka nalowale o ka hiki.

Figure 4-3 Lithium-ion intercalation/deintercalation model of lithium iron phosphate battery

Ua hoʻomohala ʻia nā kumu hoʻohālike ʻelua i ka manawa like, akā ʻoi aku ka ʻae ʻia e ka poʻe noiʻi ke kumu kumu -hoʻohālike, ʻoiai ʻo nā mea kikoʻī o ka pūpū a me ke kumu e hoʻopaʻapaʻa mau nei. Ma muli o kēia mau hiʻohiʻona ʻelua, hiki ke hoʻoholo ʻia ʻo ka diffusion kinetics o nā lithium ions a me ka uku ke kumu hoʻoholo no ka hoʻohana pono ʻana o ka mea electrode holoʻokoʻa. I ka hoʻomākaukau ʻana i nā mea lithium iron phosphate cathode, hoʻoikaika ʻia ka loaʻa ʻana o nā ʻāpana me ka liʻiliʻi liʻiliʻi a me ka nui o ka nui (nanoscale a i ʻole microporous), me ka hoʻohana ʻana i ke kalapona (nanocarbon film) a me ka doping ion e hoʻomaikaʻi i ka conductivity a me ka diffusion lithium ion.

Me ka ʻike hohonu o nā mea LiMPO, ua ʻike ʻia ua haʻalele kēia mau hiʻohiʻona ʻelua i nā ʻano anisotropic kiʻekiʻe o ka lawe ʻana i ka lithium ion i nā mea LiMPO. Hāʻawi ʻo Laffont i kahi "Kōkohu Hou{1}}shell" e hoʻoponopono i nā hemahema o ka "core-shell model." Ma ke kūkulu ʻana i kēia, ua aʻo ʻo Delmas i nā mea liʻiliʻi LiFePO ma nā mokuʻāina hoʻopau like ʻole a manaʻo ʻo "Domino - cascade Model," e wehewehe pono i ka hana wikiwiki a me ka hoʻokuʻu ʻana o nā ʻāpana nanoscale, e like me ka hōʻike ʻana ma ke Kiʻi 4-4.

ʻOiai ka ʻokoʻa koʻikoʻi ma waena o nā hiʻohiʻona i ʻōlelo ʻia aʻe nei, aia ka pilikia koʻikoʻi ma ka wānana a me ke ʻano o ka interface -ʻelua. Ma muli o ka hilinaʻi nui ʻana o nā kinetics o ka lithium insertion/extraction a me ka hoʻololi ʻana o ka pae i ka nui o ka particle, morphology, a me nā waiwai physicochemical o ka mea, ʻo nā kūkākūkā ma luna nei (me nā paio ma waena o nā kumu hoʻohālike) ma muli o ka lawa ʻole o nā kūlana hoʻokolohua.

Me ka hoʻomohala ʻana o ka microscopy a me ka spectroscopy, ua ʻike ʻia a ʻike ʻia nā hopena hoʻonā paʻa a me nā pae waena i ka wā o ka hoʻololi ʻana o nā mea LiMPO4, e hōʻike ana aia kekahi ʻano hana hoʻololi i nā mea LiMPO4. Ma nā ʻano hopena paʻa paʻa maʻamau, hōʻike nā ʻāpana cell a me ka nui o nā cell i nā loli mau i ka wā o ka hoʻololi ʻana. Ma o kekahi mau kūlana hoʻāʻo koʻikoʻi a me nā ʻano hiʻohiʻona, e like me ka ultra-liʻiliʻi (nanoscale) a me ke kiʻekiʻe-rate charge-discharge (ma luna o 10C), ua ʻike ʻia nā hopena hoʻonā paʻa a me ka noho ʻana o nā pae waena ma LiMPO4.

Nā hoʻololi ʻana i ka wā o ka hoʻouka ʻana-kaʻina hana i ka wela lumi. Hōʻike ʻia ka hoʻohuli maikaʻi ʻana o nā ʻaniani Lithium -i ka wā o ka hoʻokuʻu ʻana-hoihoi, pili i ke ʻano like o ke kūkulu ʻana ma waena o nā kūlana pae ma hope o ka lithium-ion deintercalation/intercalation. I loko o nā ka'ina ho'oku'u -ho'opi'i, pili loa ka pohō o ka mana o ka pila me nā kinetics ho'ololi. Ma muli o ka hoʻolālā o LiFePO4, ʻoi aku ka maikaʻi o ka ʻaoʻao [100]pmnb no ka neʻe ʻana o ka lithium{10}}ion, a ke neʻe nei ke kikowaena ma waena o nā ʻāpana ʻelua ma ke kaʻina c{11}}i ka wā o ka hoʻokuʻu ʻana.

(1) LiFePO₄/FePO₄The ratio of LiFePO₄/FePO₄ changes continuously with the battery charge-discharge reaction (the value of x in LiₓFePO₄ changes continuously). As lithium ions are extracted, the intensity of the diffraction peak produced by LiFePO₄ gradually decreases. When δ>0.2, hoʻomaka ka nalo ʻana o ka piko ʻokoʻa o Li₁₋δFePO₄, a piʻi mālie ka ikaika o ka piko ʻokoʻa i hana ʻia e FePO₄. ʻO ka mea ʻē aʻe, i ka hoʻokomo ʻia ʻana o nā lithium ion, e emi mālie ana ka ikaika o ka peak diffraction i hana ʻia e FePO₄, a e piʻi mālie ka ikaika o ka peak diffraction i hana ʻia e Li₁₋δFePO₄.

(2) LiₓFePO₄/Li₁₋yFePO₄ʻO LiₓFePO₄ ma ka wela lumi he hui ʻia o Fe³⁺/Fe²⁺ hui ʻia-valence mesophase LiₐFePO₄/Li₁₋ FePO₄. a e hōʻike ana i ka nui o ka mea lawe a me ka hiki ke lele i ka wā o ka hoʻouka ʻana a me ka hoʻokuʻu ʻana. Ua hōʻike ʻia ka pauku neutron diffraction ʻo nā waiwai maikaʻi loa no ka 0.05 a me 0.11. ʻO nā mea e like me ka ion doping, ka mahana, ka metala hoʻololi, ka nui o ka ʻāpana, a me nā kūlana kaulike ʻole i ka overpotential e pili ana i nā waiwai o a me . ʻO ka hoʻonui ʻana i nā waiwai a e hoʻomaikaʻi i ka hana kinetic o ka hopena electrode i ka wā o ka hoʻouka ʻana a me ka hoʻokuʻu ʻana i ka lumi lumi.

Ma ka 450 degere, aia kahi hopena paʻa o LiₓFePO₄, ʻoiai ma ka lumi wela, ʻelua mau ʻāpana metastable: Li₀.₇₅FePO₄ a me Li₀.₅FePO₄. Ma luna o 500 degere, hoʻomaka ʻo LiₓFePO₄ e decompose i loko o -huihui olivine ʻole; ʻo ka haku mele ʻana a me ka ʻike o kēia mau phosphates a i ʻole phosphides e pili ana i ka waiwai o x. Ma waena o 400 a me 500 degere, aia wale nō kahi hopena paʻa o LiₓFePO₄.

ʻOi aku ka paʻakikī o nā hoʻololi i ka wā hoʻoluʻu ma mua o ka wā hoʻomehana. ʻO ke ʻano o ka hui ʻana i ka wā hoʻoluʻu e pili ana i ka waiwai o x a me ke kaʻina hana wela. Ma ka hooluolu ana, e hoopau mua ana ka LiₓFePO₄ i ka hui ana o elua mahele ole-olivine, e pili ana ka like ana i ka waiwai mua o ka wela a me ka x. Ke emi ka mahana ma lalo (140±20 degere ), lilo ka ʻōnaehana ʻelua - i ʻōnaehana paʻakikī, kahi e noho pū ai ʻo LiFePO₄ a me FePO₄ me ʻelua mau pūhui olivine-ʻano, Liₓ₁FePO₄ a me Liₓ₂FePO₄. ʻO ka hoʻopau ʻia ʻana o kēia hui ʻana ma ka lumi wela e hoʻololi mālie ʻia ka ʻōnaehana ʻehā -i ʻōnaehana ʻelua- ʻōnaehana LiFePO₄ a me FePO₄.

Battery reaction mechanism

Loaʻa ka FePO₄ ma kekahi mau hale: ① Ma hope o ka wehe ʻana o LiFePO₄, hoʻokumu ʻia ka FePO₄ orthorhombic; ② Triclinic FePO₄ he quartz-like ka hale, me na cations tetrahedral i hoohuiia; ③ Hiki ke hoʻomākaukau ʻia ka FePO₄ monoclinic a me orthorhombic mai ko lākou mau hydrates. ʻO kēia mau ʻano crystalline a pau o FePO₄, a me FePO₄ amorphous, hiki ke hoʻololi ʻia i FePO₄ triclinic ma ka hoʻomehana ʻana.

ʻO ka hoʻololi ʻana mai LiFePO₄ a i FePO₄ he lohi a piha ʻole, akā hoʻopau ʻia ke ʻoi aku ka mahana ma mua o 500 degere. Ma lalo o nā kūlana hana o ka pākaukau, paʻa paʻa ka mea cathode. I ka wā o ka synthesis o LiFePO₄, pono e hōʻoia i ka nele o FePO₄. Inā loaʻa, e hana ʻia ka triclinic FePO₄ ma ka hoʻomehana ʻana, e loaʻa ai kahi ʻāpana aniani ʻeleʻele ʻole ʻole ma ka ʻili kino ma nā wela kiʻekiʻe.

Hiki i ka Ion doping ke hoʻomaikaʻi i ka conductivity o nā mea. Loaʻa ʻia nā mea hoʻokele semiconductor ʻano P-me ka conductivity hiki i 10⁻² S/cm ma o ka doping ion. He kaʻina hana paʻakikī loa ka Doping: ma kekahi ʻaoʻao, ʻo ka helu ʻana o ka density functional theory (DFT) o ke ʻano uila o LiFePO₄ ma lalo o ka local density approximation (LDA) a me ka generalized gradient approximation (GGA) e hōʻike ana e hōʻike ka mea i nā hiʻohiʻona o kahi mea metala a semiconductor paha, me kahi hui conduction a me valence band laula o ka like ʻana o ka haʻahaʻa. Ma ka ʻaoʻao ʻē aʻe, e noʻonoʻo ana i ka hoʻopili ʻana o nā orbital electron a me ka launa ʻana o Coulomb ma hope o ka doping ion, hiki ke hoʻomaikaʻi ʻia ke ʻano o ka hui valence band.

Hōʻike nā helu DFT o Mg- a i ʻole Cr-doped LiFePO₄ aia ka mānoanoa kiʻekiʻe loa o nā mokuʻāina uila ma kahi kokoke i ka pae Fermi, ka mea e wehewehe ai i ka hoʻokele metala o ka mea doped. ʻO ka hoʻololi ʻana i ka conductivity i hoʻokumu ʻia e ka ion doping e pili ana i kēia mau kumu:

1) Ua metallized nā ʻaoʻao o nā wahi lawe ukana.

2) Hoʻemi ka Ion doping i ka laulā o ka puʻupuʻu valence a me ke kaula conduction.

3) Ma mua o kahi koʻikoʻi koʻikoʻi, ʻo ka hawewe electron o nā ion dopant e alakaʻi i ka hoʻokumu ʻana i kahi hui conduction.

4) ʻO ke ʻano, ka noʻonoʻo, a me ka hāʻawi ʻana i nā ion dopant.

5) I loko o ka nui o nā M-O metala ʻokiʻoki, ʻike ʻia kahi kāʻei hoʻoheheʻe metala ke emi ka mamao o ka pilina M-M ma mua o 3 × 10⁻¹⁰ m.

6) I ka wā o ka synthesis, ʻo ka hoʻohui ʻana o ke kalapona kūlohelohe e hoʻoulu i ka uhi kalapona o ka mea, e hana ana i kahi ala hoʻokele kūpono.

7) Ke ano o Fe₂P. I ka wā synthesis, ʻo ka hoʻohui ʻana o ke kalapona keu e hōʻemi i ka phosphate.

Ion doping and conductivity

8) Hana ka Fe³⁺/Fe²⁺ redox ma ke ʻano he mea hoʻoikaika i ka hoʻemi ʻana o LiFePO₄.

Hōʻike ka LiFePO₄ i ka hana ʻana me nā electrolytes maʻamau. Hoʻopili nui ʻia ke ʻano electrochemical o ka mea me kona kemika ʻili i loko o ka electrolyte. ʻO ka maʻamau, puka mai kahi kiʻiʻoniʻoni passivation ma ka ʻili o ka mea. Hoʻomaʻamaʻa kēia kiʻiʻoniʻoni i ka laha lithium-ion, pale i ka nalowale o nā mea hana, a pono e kū i ka leo a me ka hoʻololi ʻana i ka ʻili i ka wā o ka lithium-ion hoʻokomo/unuhi. Loaʻa i nā kiʻiʻoniʻoni liʻiliʻi ʻo LiFePO₄ i uhi ʻia ka carbon{6}}e like me LiF, LiPF₆, LiₓFᵧ⁻, a me LiₓPOᵧFᶻ⁻.

Loaʻa i nā electrolytes maʻamau nā alkyl carbonates a me nā paʻakai lithium. Hiki i ka mea cathode ke hana i nā hopena he nui i ka electrolyte. No ka laʻana, i loko o nā haʻina LiPF₆, ʻaʻole hiki ke ʻalo ʻia ka ʻakika-base ma waena o LiFePO₄ a me ka nui o ka HF. ʻO ka loaʻa ʻana o ka HF i loko o ka electrolyte he ʻelua mau hopena pōʻino: ʻo ka mea mua, ka hoʻololi ʻana ma waena o nā ion hao a me nā protons; a ʻo ka lua, ʻo ka pane ʻana o nā liona Li a me nā iona F ma ka ʻili o ka ʻāpana e hana ai i LiF, kahi e keʻakeʻa ai i ka laha Li⁺.

Hoʻoheheʻe nā ion hao i nā electrolytes. Ua hōʻike ʻia nā hoʻāʻo ʻana i ka hoʻoheheʻe ʻana o ka ion hao o LiFePO₄ i nā electrolytes like ʻole:

1) I loko o nā electrolytes me ka ʻole o nā mea hoʻohaumia ʻakika, ʻoiai me nā mahana kiʻekiʻe, hiki ʻole ke hoʻoheheʻe ʻia o nā ion hao a me ka hopena o ka lilo nui o ka mea hana.

2) ʻO ka acidity hoʻonā kiʻekiʻe e alakaʻi i ka hoʻoheheʻe ʻana i ka hao hao.

3) ʻO ka wela kiʻekiʻe e alakaʻi i ka hoʻoheheʻe ʻana i ka hao hao.

4) ʻOi aku ka nui o ke kalapona i loko o ka mea i loaʻa ai ka paʻa o nā mea.

ʻO ka wahi hoʻopili ma waena o ka mea hana a me ka mea hoʻopaʻa paʻa e maʻalahi loa i ka corrosion. Hiki ke pale ʻia kēia ʻino ma o ka hoʻohana ʻana i ka mesophase alkaline a i ʻole ka hoʻohana ʻana i nā mea hoʻohui ʻākaika. I loko o nā ʻakika lithium-iona e hoʻohana ana i ka LiFePO₄ ma ke ʻano he cathode, hiki ke hoʻohana ʻia nā electrolytes non{3}}acid a i ʻole ka hoʻohui kalapona a i ʻole ka uhi ʻana o LiFePO₄ no ka pale ʻana i ka pohō nui.

ʻAʻole maopopo loa nā ʻano kinetic o nā mea cathode LiFePO₄. Ua mana'o nui 'ia ka nui o ka pōpō a me ka puana 'ana, ka ho'okahe 'ana, ka ho'ohehe'e 'ana i ka ion, nā kinetics i ka wā o ka ho'ololi 'ana i ke ka'ina (ho'oku'u -ka'ina hana), a me ka uhi kalapona/doping nā mea a pau e pili ana i ka hana o ka pila ma nā pākēkē ho'oku'u -'oko'a. ʻO ka doping kalapona like ʻole e hiki ke hoʻokomo ʻia nā ion lithium a me nā electrons ma ka wahi like i ka mea hana, e hōʻemi ana i ka polarization electrode.

(1) Ka hopena o ka hoʻoheheʻe ʻana ma ka hiki ʻana ʻO ka haʻahaʻa haʻahaʻa o ka LiFePO₄ maʻemaʻe e alakaʻi pololei i ka emi ʻana o ka hiki ke hoʻokuʻu kiʻekiʻe o ka pākaukau. ʻO ka conductivity o ka LiFePO₄ maʻemaʻe ma kahi o 10⁻⁹ S / cm, a hāʻule ka nui o ka hoʻokuʻu ʻana mai 148 mA·h/g ma kahi 0.2C hoʻokuʻu ʻana i 85 mA·h/g ma kahi 5C hoʻokuʻu. 'A'ole e pi'i mau ka mana ho'oku'u -ki'eki'e o ka mea cathode me ka pi'i 'ana. Ma ka conductivity haʻahaʻa, hoʻonui i ka conductivity e hoʻomaikaʻi i nā kinetics electrochemical o ka mea. Ke ʻoi aku ka nui o ka conductivity i kekahi waiwai koʻikoʻi, ʻaʻole ʻo ka conductivity ka mea e hoʻoholo ai no ka hiki ke helu o ka mea. LiFe₀.₉Ni₀.₁PO₄ (1.0 × 10⁻⁷ S/cm), me kona conductivity haʻahaʻa, hōʻike 'oi aku ka maikaʻi kiʻekiʻe kiʻekiʻe -rate hoʻokuʻu 'ana ma mua o LiFePO₄ (4.0 × 10⁻⁶ S/cm), me ka hoʻokuʻu 'ana ma 5 m/90 mA·g. he 10C ka holo ana. Hōʻike kēia ua hoʻololi paha ka hoʻopuehu lithium-ion i ka conductivity ma ke ʻano he kumu hoʻoholo i nā waiwai electrochemical o nā ʻeke lithium-ion.

(2) Hoʻoholo ʻia ka diffusion Lithium-ion diffusion Lithium-iona e nā kumu o loko a me waho. ʻO nā mea o waho e pili ana i ka nui o ka ʻāpana, ka puʻunaue, a me ka morphology. ʻO nā kumu o loko e pili nui i ka lithium-ion diffusion coefficient. He waiwai mau ka lithium-ion diffusion coefficient; ke emi nei ka hiki o ka laha ana o na iona lithium me ka hoonui ana i ka nui no ka mea e pi'i ana ke ala diffusion o na iona lithium i loko o ka particle. ʻO ka hiki ke hoʻopuehu o nā ion lithium i hoʻohālikelike ʻia i ka huinahā o ka nui o ka ʻāpana a pili pono i ka litium -ion diffusion coefficient. ʻOi aku ka hopena o ka nui o ka ʻumeke i ka laha -ion lithium ma mua o ka diffusion coefficient. Pono e hui pū ʻia ka helu helu o ka lithium{13}}ion diffusion coefficient me nā ʻano ana kikoʻī a me nā kumu hoʻohālike manaʻo. ʻO nā ʻano ana nui ka galvanostatic titration (GITT) a me ka electrochemical impedance spectroscopy (EIS a i ʻole AC Impedance).

(3) ʻElua-ʻano uila uila: Hoʻonui ʻia ka hana uila ma o ka hoʻonui ʻana i ka ʻili. I loko o -kini kiʻiʻoniʻoni lahilahi, komo nā electrons i ka ʻohi o kēia manawa aʻo nā ion lithium e komo i ka electrolyte mai ka ʻaoʻao ʻē aʻe. Me ka hoʻokumu ʻana o ka papa FePO₄, e emi ana ke kū'ē i ka neʻe electron, aʻo ka piʻi ʻana o ke kū'ē i ka neʻe lithium-iona. Hoʻomaka mua ʻo FePO₄ i nā pōʻino aniani a ulu aʻe ma nā ʻaoʻao a pau, e keʻakeʻa ana i ka laha ʻana o ka lithium -ion a hiki i ka hiki ʻole ke pakele i nā ion lithium ma ke ala [100].