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Właściwości eksploatacyjne ogniw litowych

Kurpiel W., Miedziński B.

Elektro Info

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2018

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nr 10

42--47

PL

W artykule omówiono właściwości eksploatacyjne ogniw litowych. Do najważniejszych ich zalet można zaliczyć stosunkowo szybkie ładowanie, wysoką gęstość energii i moc oraz szerszy zakres temperatur pracy w porównaniu z tradycyjnymi akumulatorami kwasowo-ołowiowymi. Z drugiej strony ogniwa te wrażliwe są na przeładowanie i nadmierne rozładowanie. Ze względu na ilość zgromadzonej energii awarie ogniw litowych mogą wywołać, w skrajnych przypadkach, zagrożenie życia oraz zdrowia ich użytkowników. Niezmiernie zatem istotnym jest zapobieganie niepożądanym stanom pracy ogniw litowych, głównie poprzez zastosowanie odpowiednich systemów BMS (Battery Management System) oraz odpowiednią zabudowę tych ogniw.

EN

The article discusses performance of lithium cells under operational conditions.. Their most important advantages include relatively fast charging, high energy density and significant power as well as a wider range of temperatures compared to traditional lead-acid batteries. However, on the other hand, these batteries are sensitive to overcharging as well as excessive discharge. Due to the large amount of energy stored, the lithium cell failures can cause, in extreme cases, a threat to the life and health of the users. Therefore, it is extremely important to prevent their unwanted states of work mainly through the use of appropriate BMS system (Battery Management System) and the appropriate housing.

2

Ciekłe elektrolity do ogniw litowych i litowo-jonowych

Świderska-Mocek A., Rudnicka E.

Przemysł Chemiczny

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2014

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T. 93, nr 4

433-437

PL

Przedstawiono ciekłe elektrolity stosowane w ogniwach litowych i litowo-jonowych. Omówiono rodzaje i właściwości soli litu, z uwzględnieniem zastosowania nowych soli, takich jak LiPF₃(C₂F₅)₃ (LiFAP), LiN(SO₂F)₂ (LiFSI) oraz bis(szczawiano)boran litu (LiBOB). Przedstawiono możliwość zastąpienia klasycznych rozpuszczalników organicznych (głównie liniowych i cyklicznych węglanów) cieczami jonowymi (IL) zapewniającymi niepalność i nielotność powstałych układów. Podkreślono rolę dodatków do elektrolitu, których obecność umożliwia tworzenie lub poprawę właściwości warstwy pasywacyjnej, co prowadzi do redukcji nieodwracalnej pojemności i wydłuża czas życia ogniw.

EN

A review, with 126 refs., of org. solvents, Li salts, ionic liqs. and additives used in Li and Li-ion batteries.

3

Delithiation of olivine - structured LiFexMn1-xPO4 cathode materials. Mössbauer studies

Marzec J., Ojczyk W., Molenda J.

Materials Science Poland

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2006

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Vol. 24, No. 1

69--74

EN

This paper presents the results of applying the 57Fe Mössbauer effect technique to studies of the delithiation mechanism of LixMn0.55Fe0.45PO4 olivine samples, and also investigations of the origin of the widely discussed, astonishing high electronic conductivity of tungsten-doped LiFePO4 samples, providing evidence of the presence of a residual, iron-containing and highly conductive phase. The delithiation process is perceived by iron ions as a change of their valence and symmetry of the local surroundings upon lithium extraction. The LixMn0.55Fe0.45PO4 compound, which belongs to a novel group of cathode materials for Li-ion batteries, exhibits a single-phase deintercalation region, in contrast to LiFePO4 exhibiting two-phase mechanism of electrochemical lithium extraction/insertion in the entire lithium concentration range, as well as to LiMnPO4, for which the deintercalation process is practically irreversible. The range of deintercalation mechanism in LixMn0.55Fe0.45PO4 was found to be exactly related to the content of Fe2+ ions in the cathode material. A surface sensitive technique, Conversion Electron Mössbauer Spectroscopy (CEMS), was used to prove the presence of traces of iron phosphides on the grain surfaces of tungsten-doped LiFePO4 samples, pointing to the minor phase as being responsible for the high electronic conductivity of these samples.

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Elektroda interkalacyjna w ogniwie litowym z niewodnym roztworem elektrolitu. [Cz.] 1. Dwutlenek manganu i tlenki litowo-manganowe

Bełtowska-Brzezińska M., Kozik T., Jaworska H.

Wiadomości Chemiczne

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2001

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[Z] 55, 3-4

289-329

EN

Lithium batteries of various types have found use in portable electronic devices and are also considered for application in electric or hybrid vehicles because of their high operating voltage and energy density. Among a number of materials examined as the positive electrode in lithium batteries with organic electrolyte solution, much attention has been paid to transition metal oxides, in particular to manganese dioxide and its lithiated derivatives. Electrochemical studies have proved that these compounds are able to accommodate or remove Li+ ions in parallel with the electron injection or extraction thus changing the oxidation state of manganese (IV/III) upon the solid state redox reaction. The capacity and power density of intercalation electrodes varies with the crystallographic and electronic structure of their solid phase, electrode thickness and porosity as well as the chemical nature and conductivity of the electrolyte solution. The kinetics of the electrochemical intercalation-deintercalation of Li+ ions is mostly limited by the diffusion of these ions into or from the host matrix. Another limitation comes from an electrolyte depletion in pores of the electrode material during the discharge, as the rate of the Li+ ions transport from the bulk electrolyte is lower in comparison with the charge transfer rate at the electrode/electrolyte interface. The diffusion model for nonporous and porous intercalation electrodes quite well describes the surface and bulk distribution of Li+ ions in the solid phase as well as in the pore electrolyte, as a function of the discharge rate and discharge degree. The experimental characteristics of MnO2 and compounds of the Li-Mn-O system, obtained at various electrode thickness, particle size and charge-discharge density has confirmed the theoretical predictions. Manganese dioxide (g-MnO2) electrodes having discharge capacity of 220-270 Ah/kg at Eť3 V vs. Li/Li+ show a limited rechargeability on charge-discharge cycling in secondary lithium cells. As evidenced by XRD-ray patterns this is due to anisotropic expansion and contraction of the crystallographic unit cell at the average manganese valence of about +3.5. A significantly higher cycling efficiency can be achieved with MnO2(CDMO) and Li-Mn-O spinel phases, providing a three-dimensional interstitial space for Li+ ions transport. The cubic close-packed structure of the stoichiometric LiMn2O4 remains almost unchanged upon deintercalation to l-MnO2 and subsequent reintercalation to x ť 1 in the potential range E ť 4 V (vs. Li/Li+). One can obtain the rechargeable capacity of 125 Ah/kg at moderate current rates owing to the relatively fast solid state diffusion of Li+ ions for 0< x <1. Two further potential plateau's at E ť 3 V and E ť 1 V correspond to the intercalation degree of 1< x <2 and 2< x <4 upon a cubic-tetragonal and tetragonal-trygonal phase transition, respectively. The identification of three distinct regions in the potential-composition (E-x) curves at makes the basis for spinel electrodes application in energy storage devices. In the last years, several overlithiated and defect spinel phases of the general formula (...) have been used in the so-called "lithium-ion" batteries with the carbon based negative electrode. Alternative lihium-ion batteries contain two transition metal oxides having different intercalation potentials. Quite recently, a family of mixed spinel oxides Li (...) has been proposed for the positive electrode, Li[Li0,33Ti1,67]O4 as the negative electrode. Future improvement of the charge-discharge performance of spinel electrodes for primary and secondary lithium batteries can be expected under a complex optimisation of the synthesis methods, the electrode mophology, porosity and thickness. Furthermore, the advanced batteries require the high conductivity electrolyte-solvent systems, stable in the potential range of at least 0 to 5V.