With the use of lithium batteries, battery performance continues to decay, mainly as capacity decay, internal resistance increase, power drop, etc. The change of battery internal resistance is affected by various usage conditions such as temperature and discharge depth. Therefore, the factors that affect the internal resistance of the battery are described in terms of battery structure design, raw material performance, manufacturing process and use conditions.

Ho hanyetsa ke khanyetso eo betri ea lithium e e fumanang ha hona joale e phalla ka hare ho betri ha e sebetsa. Ka kakaretso, khanyetso ea ka hare ea libeteri tsa lithium e arotsoe ka ho hanyetsa ka hare ho ohmic le ho hanyetsa ka hare ho polarization. Ho hanyetsa ka hare ho ohmic ho entsoe ka thepa ea electrode, electrolyte, diaphragm resistance le ho hanyetsa ho kopana ha karolo ka ‘ngoe. Polarization ka hare ho hanyetsa ho bolela ho hanyetsa ho bakoang ke polarization nakong ea karabelo ea electrochemical, ho kenyelletsa le electrochemical polarization internal resistance le concentration polarization internal resistance. Ho hanyetsa ka hare ho ohmic ka hare ho betri ho khethoa ke conductivity e feletseng ea betri, ‘me ho hanyetsa ha betri ka hare ho polarization ho khethoa ke coefficient e tiileng ea phallo ea li-ion tsa lithium ka thepa e sebetsang ea electrode.

Ohm khanyetso

Khanyetso ea ohmic e arotsoe haholo ka likarolo tse tharo, e ‘ngoe ke ionic impedance, e’ ngoe ke impedance ea elektroniki, ‘me ea boraro ke ho ikopanya le impedance. Re tšepa hore khanyetso ea ka hare ea betri ea lithium e nyenyane ka hohle kamoo ho ka khonehang, kahoo re lokela ho nka mehato e tobileng ho fokotsa ho hanyetsa ka hare ho ohmic bakeng sa lintho tsena tse tharo.

Ion impedance

Lithium battery ion resistance refers to the resistance to the transmission of lithium ions inside the battery. In a lithium battery, the lithium ion migration speed and the electron conduction speed play an equally important role, and the ion resistance is mainly affected by the positive and negative electrode materials, the separator, and the electrolyte. To reduce ion impedance, you need to do the following:

Etsa bonnete ba hore lisebelisoa tse ntle le tse mpe le electrolyte li na le mongobo o motle

Hoa hlokahala ho khetha sekhahla se loketseng sa compaction ha ho etsoa moralo oa palo. Haeba compaction density e le kholo haholo, electrolyte ha e bonolo ho kenella, e leng ho tla eketsa khanyetso ea ion. Bakeng sa karolo e mpe ea palo, haeba filimi ea SEI e entsoeng holim’a thepa e sebetsang nakong ea tefiso ea pele le ho tsoa e teteaneng haholo, e tla boela e eketsehe ho hanyetsa ion. Ka nako ena, hoa hlokahala ho lokisa mokhoa oa ho theha betri ho e rarolla.

Tšusumetso ea electrolyte

Electrolyte e tlameha ho ba le mahloriso a nepahetseng, viscosity le conductivity. Ha viscosity ea electrolyte e phahame haholo, ha e lumellane le ho kenella pakeng tsa electrolyte le lisebelisoa tse sebetsang tsa li-electrode tse ntle le tse mpe. Ka nako e ts’oanang, electrolyte e boetse e hloka khatello e tlaase, khatello e phahameng haholo le eona ha e lumellane le phallo le ho kenella ha eona. The conductivity ea electrolyte ke ntlha ea bohlokoa ka ho fetisisa e amang ho hanyetsa ion, e leng se khethollang ho falla ha li-ion.

Tšusumetso ea diaphragm ho hanyetsa ion

The main influencing factors of the diaphragm on the ion resistance are: electrolyte distribution in the diaphragm, diaphragm area, thickness, pore size, porosity, and tortuosity coefficient. For ceramic diaphragms, it is also necessary to prevent ceramic particles from blocking the pores of the diaphragm, which is not conducive to the passage of ions. While ensuring that the electrolyte is fully infiltrated into the diaphragm, there should be no excess electrolyte remaining in it, which reduces the efficiency of the electrolyte.

Elektronike impedance

Ho na le lintlha tse ngata tse susumetsang tsa impedance ea elektroniki, e ka ntlafatsoang ho tsoa likarolong tse kang lisebelisoa le lits’ebetso.

Positive and negative plates

The main factors affecting the electronic impedance of the positive and negative plates are: the contact between the active material and the current collector, the factors of the active material itself, and the parameters of the plate. The active material should be in full contact with the current collector surface, which can be considered from the current collector copper foil, aluminum foil base material, and the adhesion of the positive and negative electrode pastes. The porosity of the living material itself, the by-products on the surface of the particles, and the uneven mixing with the conductive agent, etc., will cause the electronic impedance to change. Polar plate parameters such as the density of living matter is too small, the gap between the particles is too large, which is not conducive to electron conduction.

Diaphragm

Lintlha tse ka sehloohong tse amang tšitiso ea elektronike ea diaphragm ke: botenya ba diaphragm, porosity, le lihlahisoa tsa thepa le ts’ebetso ea ho tsoa. Tse peli tsa pele li bonolo ho li utloisisa. Ka mor’a hore betri e qhaqholloe, hangata ho na le lesela le teteaneng la lintho tse sootho ho karohano, ho kenyelletsa le electrode e fosahetseng ea graphite le karabelo ea eona ka lihlahisoa, tse tla thibela li-pores tsa diaphragm le ho fokotsa bophelo ba tšebeletso ea betri.

Mokelli oa hona joale oa substrate

The material, thickness, width of the current collector and the degree of contact with the tabs all affect the electronic impedance. The current collector needs to choose a substrate that has not been oxidized and passivated, otherwise it will affect the impedance. Poor welding between copper and aluminum foil and tabs will also affect electronic impedance.

Ikopanye le ho hanyetsa

Ho hanyetsa ho kopana ho thehoa pakeng tsa ho kopana pakeng tsa koporo le aluminium foil le thepa e sebetsang, ‘me tlhokomelo e lokela ho lefshoa ho khomarela li-electrode tse ntle le tse mpe.

Polarized ka hare ho hanyetsa

Ha hona joale e feta ka li-electrode, ketsahalo ea hore motlakase o ka kheloha matla a motlakase a lekanang a bitsoa electrode polarization. Polarization e kenyelletsa polarization ea ohmic, polarization ea electrochemical le polarization ea mahloriso. Ho hanyetsa polarization ho bolela ho hanyetsa ka hare ho bakoang ke polarization ea electrode e ntle le electrode e mpe ea betri nakong ea karabelo ea electrochemical. E ka bonahatsa ho tsitsa ha ka hare ho betri, empa ha e loketse tlhahiso ka lebaka la tšusumetso ea ts’ebetso le mokhoa. Khahlano ea ka hare ea polarization ha e fetohe, ‘me e fetoha le nako nakong ea ts’ebetso ea ho tjhaja le ho ntša. Lebaka ke hore sebopeho sa thepa e sebetsang, mahloriso le mocheso oa electrolyte li lula li fetoha. Ho hanyetsa ka hare ho ohmic ho mamela molao oa Ohm, ‘me ho hanyetsa ha ka hare ho polarization ho eketseha ka ho eketseha ha sekhahla sa hona joale, empa ha se kamano ea moeli. Hangata e eketseha ka mokhoa o tšoanang ha logarithm ea sekhahla sa hona joale e ntse e eketseha.

Tšusumetso ea moralo oa sebopeho

Ka moralo oa sebopeho sa betri, ntle le ho riveting le welding ea sebopeho sa betri ka boeona, palo, boholo, le sebaka sa li-tab tsa betri li ama ka kotloloho ho hanyetsa ka hare ho betri. Ho isa bohōleng bo itseng, ho eketsa palo ea li-tab ho ka fokotsa ka katleho khanyetso ea ka hare ea betri. Boemo ba li-tab bo boetse bo ama matla a ka hare a betri. Ho hanyetsa ka hare ho betri ea leqeba le boemo ba tab ka hlooho ea likotoana tse ntle le tse mpe ke tse kholo ka ho fetisisa. Ha ho bapisoa le betri ea leqeba, beteri ea laminated e lekana le libeteri tse ngata tse nyane ka ho bapa. , Ho hanyetsa ha eona ka hare ho nyenyane.

Tšusumetso ea ts’ebetso ea thepa e tala

Positive and negative active materials

Ka libeteri tsa lithium, lisebelisoa tse ntle tsa electrode ke karolo ea polokelo ea lithium, e leng eona e khethollang haholoanyane ts’ebetso ea betri ea lithium. Thepa e ntle ea elektrode haholo-holo e ntlafatsa conductivity ea elektronike pakeng tsa likaroloana ka ho roala le doping. Ka mohlala, doping e nang le Ni e matlafatsa matla a PO bond, e tsitsisa sebopeho sa LiFePO4 / C, e ntlafatsa molumo oa sele, ‘me e ka fokotsa ka katleho ho hanyetsa phetiso ea tefiso ea thepa e ntle ea electrode. Keketseho e kholo ea polarization ea ts’ebetso, haholo-holo ts’ebetso ea polarization ea electrode e mpe, ke lebaka le ka sehloohong la polarization e tebileng. Ho fokotsa boholo ba likaroloana tsa electrode e mpe ho ka fokotsa ka katleho polarization e sebetsang ea electrode e mpe. Ha karolo e tiileng ea karoloana ea eleketrode e mpe e fokotseha ka halofo, polarization e sebetsang e ka fokotsoa ka 45%. Ka hona, mabapi le moralo oa betri, lipatlisiso mabapi le ntlafatso ea lisebelisoa tse ntle le tse mpe le tsona lia hlokahala.

Moemeli ea tsamaisang

Graphite le carbon black li sebelisoa haholo tšimong ea libeteri tsa lithium ka lebaka la thepa ea tsona e ntle. Ha ho bapisoa le graphite-based conductive agent, electrode e ntle e nang le carbon black-based conductive agent e na le ts’ebetso e ntle ea lebelo la betri, hobane graphite-based conductive agent e na le flaky particle morphology, e bakang keketseho e kholo ea pore tortuosity ka tekanyo e kholo. Ho bonolo ho etsahala Li liquid phase diffusion Ketsahalo ea hore ts’ebetso e fokotsa matla a ho qhala. Betri e nang le CNTs e kenyelelitsoeng e na le khanyetso e tlaase ea ka hare, hobane ha e bapisoa le ntlha ea ho kopana pakeng tsa graphite / carbon black le thepa e sebetsang, li-fibrous carbon nanotubes li tsamaisana le lisebelisoa tse sebetsang, tse ka fokotsang ho senyeha ha sebopeho sa betri.

‘Mokelli oa hona joale

Ho fokotsa ho hanyetsa ha li-interface pakeng tsa mokelli oa hona joale le thepa e sebetsang le ho ntlafatsa matla a ho kopanya pakeng tsa tse peli ke mekhoa ea bohlokoa ea ho ntlafatsa ts’ebetso ea libeteri tsa lithium. Ho roala sekoaelo sa khabone ka holim’a foil ea aluminium le kalafo ea corona holim’a foil ea aluminium ho ka fokotsa ka nepo ho sitisa sehokelo sa betri. Ha ho bapisoa le foil e tloaelehileng ea aluminium, tšebeliso ea carbon-coated aluminium foil e ka fokotsa khanyetso ea ka hare ea betri ka hoo e ka bang 65%, ‘me e ka fokotsa keketseho ea khanyetso ea ka hare ea betri nakong ea tšebeliso. Khanyetso ea kahare ea AC ea foil ea aluminium e phekotsoeng ea corona e ka fokotsoa ka hoo e ka bang 20%. Sebakeng se tloaelehileng sa 20% ~ 90% SOC, khanyetso ea kahare ea DC e batla e le nyane mme keketseho e nyane butle butle ha botebo ba ho tsoa bo ntse bo eketseha.

Diaphragm

The ion conduction inside the battery depends on the diffusion of Li ions in the electrolyte through the porous diaphragm. The liquid absorption and wetting ability of the diaphragm is the key to forming a good ion flow channel. When the diaphragm has a higher liquid absorption rate and porous structure, it can be improved. Conductivity reduces battery impedance and improves battery rate performance. Compared with ordinary base membranes, ceramic diaphragms and rubber-coated diaphragms can not only greatly improve the high temperature shrinkage resistance of the diaphragm, but also enhance the liquid absorption and wetting ability of the diaphragm. The addition of SiO2 ceramic coating on the PP diaphragm can make the diaphragm absorb liquid The volume increased by 17%. Coating 1μm PVDF-HFP on the PP/PE composite diaphragm, the liquid absorption rate of the diaphragm is increased from 70% to 82%, and the internal resistance of the cell is reduced by more than 20%.

Ho tsoa likarolong tsa ts’ebetso ea tlhahiso le maemo a ts’ebeliso, lintlha tse amang khanyetso ea kahare ea betri haholo-holo li kenyelletsa:

Lintlha tsa ts’ebetso li ama

Ho hula

Ho ts’oana ha ho qhalakanngoa ha slurry nakong ea ho kopanya ho ama hore na moemeli oa conductive a ka qhalakanngoa ka mokhoa o ts’oanang le thepa e sebetsang e amanang le eona, e amanang le ho hanyetsa ka hare ho betri. Ka ho eketsa ho hasana ka lebelo le phahameng, ho ts’oana ha ho qhalakanngoa ha slurry ho ka ntlafatsoa, ​​’me ho hanyetsa ka hare ho betri ho tla ba nyenyane. Ka ho eketsa surfactant, ho tšoana ha kabo ea mochine o tsamaisang motlakase ho electrode ho ka ntlafatsoa, ​​’me polarization ea electrochemical e ka fokotsoa’ me motlakase oa bohareng o ka eketseha.

barbotage

Tekanyo ea sebaka ke e ‘ngoe ea likarolo tsa bohlokoa tsa moralo oa betri. Ha matla a betri a lula a le teng, ho eketsa sekhahla sa holim’a likotoana tsa lipalo ho tla fokotsa bolelele ba moqokelli oa hona joale le diaphragm, ‘me ho hanyetsa ohmic ea betri ho tla fokotseha ka tsela e nepahetseng. Ka hona, ka har’a mefuta e itseng, ho hanyetsa ka hare ho betri ho fokotseha ha boima ba sebaka bo ntse bo eketseha. Ho falla le ho arohana ha limolek’hule tsa solvent nakong ea ho roala le ho omisa ho amana haufi-ufi le mocheso oa ontong, o amang ka ho toba ho ajoa ha binder le conductive moemeli oa palo, ebe o ama sebopeho sa marang-rang a conductive ka hare ho poleiti. Ka hona, mokhoa oa ho roala le ho omisa Mocheso le oona ke mokhoa oa bohlokoa oa ho ntlafatsa tshebetso ea betri.

phethola

Ho isa boholeng bo itseng, khanyetso e ka hare ea betri ea fokotseha ha boima ba compaction bo ntse bo eketseha. Hobane compaction density e eketseha, sebaka se pakeng tsa likaroloana tse tala sea fokotseha. Ho kopana ho eketsehileng pakeng tsa likaroloana, marokho le likanale tse tsamaisang haholoanyane, le betri The impedance e fokotsehile. Taolo ea compaction density e finyelloa haholo-holo ka botenya ba rolling. Botenya bo fapaneng ba ho roala bo na le tšusumetso e kholo ho khanyeng ea kahare ea betri. Ha botenya ba rolling bo le boholo, khanyetso ea ho kopana pakeng tsa thepa e sebetsang le mokelli oa hona joale e eketseha ka lebaka la ho hlōleha ha thepa e sebetsang e lokelang ho phuthoa ka thata, ‘me ho hanyetsa ka hare ho betri hoa eketseha. Ka mor’a hore betri e tsamaee ka baesekele, mapetsong a hlahisoa ka holim’a elektrode e ntle ea betri e nang le botenya bo batlang bo le botenya, e leng ho tla eketsa ho hanyetsa ho kopana pakeng tsa thepa e sebetsang ea holim’a palo le mokelli oa hona joale.

Nako ea ho khutlisa karolo ea poleiti

Nako e fapaneng ea sethala sa electrode e ntle e na le tšusumetso e kholo ho hanyetsa ka hare ho betri. Ha nako ea sethala e le khutšoanyane, ho hanyetsa ka hare ho betri ho tla eketseha butle-butle ka lebaka la phello ea carbon coating layer holim’a lithium iron phosphate le lithium iron phosphate; Ha betri e sala nako e telele (ho feta 23h), ho hanyetsa ka hare ho betri ho eketseha haholo ka lebaka la phello e kopantsoeng ea karabelo ea lithium iron phosphate ka metsi le ho khomarela sekhomaretsi. Ka hona, hoa hlokahala ho laola ka thata nako ea ho fetoha ha likotoana tsa pole tlhahisong ea ‘nete.

Ente ea mokelikeli

Ionic conductivity ea electrolyte e etsa qeto ea ho hanyetsa ka hare le litekanyetso tsa litekanyetso tsa betri. The conductivity ea electrolyte e inversely tekano ho viscosity ea solvent, ‘me e boetse e angoa ke mahloriso a lithium letsoai le boholo ba anions. Ntle le lipatlisiso tsa optimization mabapi le conductivity, bophahamo ba ente le nako ea ho kenella ka mor’a ente le tsona li ama ka kotloloho ho hanyetsa ka hare ho betri. Bophahamo ba ente e nyane kapa nako e sa lekaneng ea ho kenella e tla etsa hore khanyetso ea kahare ea betri e be kholo haholo, kahoo e tla ama betri Bokhoni ba ho bapala.

Tšusumetso ea maemo a tšebeliso

mocheso

Tšusumetso ea mocheso ho hanyetsa ka hare e hlakile. Ha mocheso o le tlase, phetisetso ea ion ka har’a betri e ea butle le ho hanyetsa ka hare ho betri. Phetetso ea betri e ka aroloa ka bongata bo bongata, ho thibela membrane ea SEI, le phetisetso ea phetisetso ea litefiso. The impedance e ngata le SEI membrane impedance angoa haholo-holo ke electrolyte ionic conductivity, ‘me mokhoa oa ho fetoha ha mocheso o tlaase o lumellana le phetoho ea phetoho ea electrolyte conductivity. Ha ho bapisoa le keketseho ea ho hanyetsa ka bongata le khanyetso ea filimi ea SEI ka mocheso o tlase, impedance ea karabelo ea tefiso e eketseha haholo ka ho fokotseha ha mocheso. Ka tlase ho -20 ° C, ts’ebetso ea ts’ebetso ea tefiso e baka hoo e ka bang 100% ea khanyetso e felletseng ea betri.

SOC

Ha betri e le ho SOC e fapaneng, ho hanyetsa ha eona ka hare ho boetse ho fapane, haholo-holo khanyetso ea ka hare ea DC e ama ka ho toba ts’ebetso ea matla a betri, ebe e bonahatsa ts’ebetso ea betri sebakeng sa sebele: khanyetso ea ka hare ea DC ea betri ea lithium e fapana le botebo ba ho ntša DOD ea betri Ho hanyetsa ka hare ha e le hantle ha ho fetohe nakong ea 10% ~ 80% ea ho qeta nako. Ka kakaretso, khanyetso ea ka hare e eketseha haholo ka botebo bo tebileng ba ho tsoa.

polokelo

Ha nako ea polokelo ea libeteri tsa lithium-ion e ntse e eketseha, libeteri li tsoela pele ho tsofala, ‘me ho hanyetsa ha tsona ka hare ho ntse ho eketseha. Mefuta e fapaneng ea libeteri tsa lithium e na le likhato tse fapaneng tsa phetoho ho hanyetsa ka hare. Ka mor’a nako e telele ea polokelo bakeng sa likhoeli tsa 9-10, tekanyo ea ho eketseha ha khanyetso ea ka hare ea libeteri tsa LFP e phahame ho feta ea libethe tsa NCA le NCM. Sekhahla sa keketseho ea ho hanyetsa ka hare se amana le nako ea polokelo, mocheso oa polokelo le SOC ea polokelo

Potoloho

Ebang ke ho boloka kapa ho palama baesekele, mocheso o na le phello e tšoanang ho hanyetsa ka hare ho betri. Ha mocheso oa potoloho o phahame, ho feta tekanyo ea keketseho ea ho hanyetsa ka hare. Likhahla tse fapaneng tsa potoloho li na le litlamorao tse fapaneng mabapi le ho hanyetsa ka hare ho betri. Ho hanyetsa ka hare ho betri ho eketseha ka ho eketseha ha botebo ba tefiso le ho tsoa, ​​’me ho eketseha ha khanyetso ea ka hare ho lekana le ho eketseha ha botebo ba tefiso le ho tsoa. Ntle le tšusumetso ea botebo ba tefiso le ho tsoa ka potoloho, motlakase o khaotsoeng o boetse o na le tšusumetso: moeli o tlase haholo kapa o phahameng haholo oa motlakase oa tefiso o tla eketsa tšitiso ea sebopeho sa elektrode, le filimi ea passivation e ke ke ea etsoa hantle ka tlas’a mocheso o tlaase haholo oa moeli o ka holimo, ‘me Moeli o phahameng haholo oa mocheso o ka holimo o tla etsa hore electrolyte e oxidize le ho senyeha holim’a motlakase oa LiFePO4 ho etsa lihlahisoa tse nang le motlakase o fokolang oa motlakase.

tse ling

Libetri tsa lithium tse kentsoeng ka koloing li tla ba le maemo a mabe a litsela lits’ebetsong tse sebetsang, empa liphuputso li fumane hore tikoloho ea vibrate ea betri ea lithium e batla e se na phello ea ho hanyetsa ka hare ho betri ea lithium nakong ea ts’ebetso ea kopo.

Outlook

Ho hanyetsa ka hare ke parameter ea bohlokoa ho lekanya ts’ebetso ea matla a lithium-ion le ho lekola bophelo ba betri. E kholoanyane ho hanyetsa ka hare, ho mpefala ha lebelo la ts’ebetso ea betri, ‘me e eketseha ka potlako nakong ea ho boloka le ho tsosolosa. Ho hanyetsa ka hare ho amana le sebopeho sa betri, litšobotsi tsa lisebelisoa tsa betri le ts’ebetso ea tlhahiso, le liphetoho ka liphetoho tsa mocheso o potolohileng le boemo ba tefiso. Ka hona, nts’etsopele ea li-betri tse tlase tse hanyetsang ka hare ke senotlolo sa ho ntlafatsa ts’ebetso ea matla a betri, ‘me ka nako e ts’oanang, ho tseba melao e fetohang ea ho hanyetsa ka hare ho betri ho na le bohlokoa ba bohlokoa bo sebetsang bakeng sa ho bolela esale pele bophelo ba betri.