19 research outputs found
Elektrody pro superkondenzátory
Supercapacitors are designed and used for temporary storage of electric energy. On contrary to batteries, the process of chargé accumulations occurs at the boundary between solid electrode and electrolyte. Hence, the physical surface of the electrode must he fairly high. The aim of this contribution is the description of electrodes with highly developed surface and consisting of nanosized particles
ProgresivnĂ elektrodovĂ© materiály pro lithno-iontovĂ© akumulátory: Kladná elektroda na bázi elementárnĂ sĂry
ÄŚlánek se zabĂ˝vá problematikou elektrodovĂ˝ch hmot pro lithno-iontovĂ© akumulátory, je Ăşzce zaměřen na vlastnosti elementárnĂ sĂry z hlediska jejĂho vyuĹľitĂ pro elektrochemickou akumulaci energie v rámci kladnĂ© elektrody. SĂra je jako aktivnĂ elektrodovĂ˝ materiál velmi perspektivnĂm nástupcem stávajĂcĂch konvenÄŤnĂch elektrodovĂ˝ch materiálĹŻ kladnĂ˝ch elektrod (LiCoO2, LiMn204, LiFePO4) a to pĹ™edevšĂm dĂky svĂ© energetickĂ© hustotÄ›, dostupnosti a cenÄ›. Ve svÄ›tÄ› se vĂ˝vojem bateriĂ s katodou s obsahem sĂry zabĂ˝vá mnoĹľstvĂ vÄ›deckĂ˝ch tĂ˝mĹŻ, ale v ÄŚR je tato naše snaha prozatĂm ojedinÄ›lá. V rámci tohoto ÄŤlánku je nastĂnÄ›n principiálnĂ rozdĂl v ÄŤinnosti konvenÄŤnĂch interkalaÄŤnĂch a novĂ©ho konceptu konverznĂch elektrodovĂ˝ch materiálĹŻ, budou zde uvedeny elektrickĂ© a elektrochemickĂ© vlastnosti sĂry. Jádrem pĹ™ĂspÄ›vku je popis laboratornĂ pĹ™Ăpravy kompozitnĂho elektrodovĂ©ho materiálu Super P/S zaloĹľenĂ©ho na impregnaci pĂłrĹŻ uhlĂku Timcal Super P rozpuštÄ›nou a částeÄŤnÄ› sublimovanĹŻou elementárnĂ sĂrou. Dále bude popsáno sestavenĂ malĂ© baterie lithium-sĂra a budou prezentovány vĂ˝sledky měřenĂ pomocĂ metod cyklickĂ© voltametrie a galvanostatickĂ©ho cyklovánĂ. StrukturnĂ charakterizace bude provedena pomocĂ rastrovacĂho elektronovĂ©ho mikroskopu a prvkovĂ© analĂ˝zy energiovÄ› disperznĂ spektroskopiĂ.This article deals with the electrode materials for lithium-ion batteries and is focused especially on the properties of elemental sulfur in terms of its utilization in electrochemical accumulation of energy within li-ion battery cathodes. Sulfur as an electrode material is one of the most promising successors of conventional cathode electrode materials due to its specific capacity, power density and price. The core of this article is aimed to the preparation of carbon/sulfur composite electrode material and to assembling of small lab scale lithium-sulfur cell. Results of cyclical voltammetry and galvanostatic cycling will be presented as well as SEM images and EDS spectra
Carbon based materials: their properties and application as electrodes in electrochemical double layer capacitors
Two types of commercially available carbon blacks were studied by cyclic voltammetry and electrochemical impedance
spectroscopy as electrode materials for supercapacitors in the 0.5 M electrolyte of propylene carbonate and LiClO4. Specific
capacitances were calculated from cyclic voltammograms and impedance spectra were fitted, so resistance of electrode was
calculated. A correlation was found between specific capacity, electrode resistance and specific surface area of carbon materials
Teplotnà závislosti měrné vodivostà aprotických elektrolytů
Článek se zabývá studiem vlastnostà aprotických elektrolytů pro lithno – iontové systémy. Byla změřena teplotnà závislost měrné vodivosti elektrolytů od pokojové teploty do 90 °C a stanovena materiálová konstanta α a zdánliva aktivačnà energie Ea. Jako rozpouštědla pro elektrolyty byly použity dipólové rozpouštědla s relativnà permitivitou v rozsahu 2 až 3 dimethyl karbnoát (DMC) a diethyl karbonát (DEC) a silně dipólové rozpouštědla s relativnà permitivitou v rozsahu 40 až 90 sulfolan (SL), propylen karbonát (PC), ethylen karbonát (EC), dimethylsulfoxid (DMSOX).This paper deals with aprotic electrolytes properties for the lithium ion systems. The temperature dependence of specific conductivity was measured and that form room temperature to 90 °C. The material constant α and activation energy E a were determined. Dipole and strong dipole solvents were used for measurement. The dipole solvents with relative permittivity 2 to 3 dimethyl carbonate (DMC) and diethyl carbonate (DEC) were used. The strong dipole solvents with relative permittivity 40 to 90 sulfolane (SL), propylene carbonate (PC), ethylene carbonate (EC) and dimethyl sulfoxide (DMSOX) were used
Stanovenà potenciálových oken a kapacity dvojvrstvy elektrolytů na bázi sulfolanu
Akumulátory jsou naprostou běžnou součástĂ lidskĂ© kaĹľdodennĂ ÄŤinnosti. VĹľdy se jedná o nÄ›kterĂ˝ druh elektrochemickĂ©ho zdroje elektrickĂ© energie jako nikl-metalhydrydovĂ©, nikl – kadmiovĂ©, lithio – jodovĂ© nebo nejrozšĂĹ™enÄ›jšà lithium iontovĂ©. ModernĂ lithno – iontovĂ© akumulátory se skládajĂ u kladnĂ© elektrody sestávajĂcĂ se vÄ›tšinou z lithium kobalt oxidu LiCoO2, polyethylenovĂ©ho nebo polypropylenovĂ©ho separatoru, elektrolytu na bázi organickĂ˝ch bezvodĂ˝ch rozpouštÄ›del a zápornĂ© elektrody vyrobenĂ© z uhlĂkatĂ©ho materiálu. VÄ›tšina tÄ›chto materiálu je hoĹ™lavĂ˝ch a proto je potĹ™eba hledat novĂ© materiály, kterĂ© budou sniĹľovat hoĹ™lavost akumulátoru. Jednou z moĹľnostĂ je pouĹľĂt mĂ©nÄ› hoĹ™lavá rozpouštÄ›dla v elektrolytu, jako vhodnĂ˝ kandidát se jevĂ sulfolan a jeho smÄ›si. Práce se zabĂ˝vá stanovenĂm potenciálovĂ˝ch oken tÄ›chto elektrolytĹŻ pro pouĹľitĂ jak v standartnĂch elektrolytech tak jako elektrolyty pro novĂ© „vysokonapěťové“ 5 V akumulátory. Pro stanovenĂ kompatibility elektrolytu s elektrodovĂ˝m materiálem je urÄŤována kapacity dvojvrstvy, kterĂ© má vĂ˝znamnĂ vliv na vlastnosti akumulátoru z pohledu cyklovatelnosti a celkovĂ© kapacity ÄŤlánku.Batteries are common part of human daily activities. Batteries are always some kind of electrochemical sources of electric energy like nickel – methylhydrid, nickel – cadmium, lithium – iodide or the most widespread litnium – ion. Modern lithium – ion batteries are composed from positive electrode, which is mostly lithium cobalt oxide LiCoO2, polypropylene or polyethylene separator, electrolytes on organic waterless solvent base and negative electrode made from carbon material. Most part of this materials is flammable and that is the reason for search new materials, which will reduce the flammability of batteries. One possibility is to use low flammable solvents for electrolytes such as sulfolane and its mixtures. This work is focused on determination of potential window of these solvents for both these common used batteries and new “high voltage” 5 V batteries. For the compatibility of electrolyte and electrode material is the double layer capacity determined which affecting the cyclic number and total capacity of batteries
Improved Electrochemical Performance of NCM Cathode Materials Based on the Modification of the Salt Content in the Electrolyte
In this work, NCM cathode materials, for Li-ion batteries, were synthesized via a solid-state reaction routine, in which manganese (IV) dioxide, nickel (II) oxide, cobalt (II) hydroxide and lithium hydroxide monohydrate were employed as metal precursors with different calcination temperature. The prepared materials were used as a cathode material for lithium-ion batteries and the electrochemical performance was studied by galvanostatic chargedischarge cycling, cyclic voltammetry, electrochemical impedance spectroscopy and rate capability, in which as electrolyte, 1M and 1.5M LiPF6 in a mixture of ethylene carbonate and dimethyl carbonate (EC:DMC- 1:1 w/w and 1:2 w/w, respectively) were employed
Metal deposition in absence of convective mass transport in polymer gel electrolytes: a model of lithium anode in batteries
Zkoumáno bylo ochuzenĂ PMMA gelovĂ© elektrody obsahujĂcĂ binárnĂ elektrolyt (chloristan kademnatĂ˝ Cd(ClO4)2 v propylen karbonátu PC). ImpedanÄŤnĂ spektra byla měřena pĹ™ed a po záznamu voltamogramu pĹ™i elektrodepozici kadmia. Vyhodnoceno bylo zvýšenĂ odporu elektrolytu vlivem polarizaÄŤnĂch ztrát a kapacity jednotlivĂ˝ch komponent. Všechny tyto parametry ukazujĂ silnĂ˝ Ăşbytek iontĹŻ, kterĂ˝ je známĂ˝ v Li polymernĂch sekundárnĂch ÄŤláncĂch, a kterĂ˝ byl snĂĹľen, kdyĹľ část chloristanu kademnatĂ©ho byla nahrazena odpovĂdajĂcà částkou chloristanu lithnĂ©ho LiClO4 jako indiferentnĂho elektrolytu.The depletion of PMMA gel polymer electrode containing a binary electrolyte (cadmium perchlorate Cd(ClO4)2 in propylene carbonate PC) has been investigated. Impedance spectra were measured before and after recording a voltammogram of cadmium electrodeposition. The increase of electrolyte resistance, of polarisation resistance, and capacity component were evaluated. All these parameters indicate a strong depletion, which is known in Li polymer secondary cells, and which was lowered if a part of cadmium perchlorate was replaced by corresponding amount of LiClO4 as an indifferent electrolyte
Capacity of a glassy carbon electrode in propylene carbonate based electrolytes
The capacity of glassy carbon in aprotic salt solutions in propylene carbonate (PC) is investigated as an approach to the optimalisation of electrochemical supercapacitors. The strong influence of water residuum on capacities at negative potentials is indicated. The capacities exhibit a shallow minimum at potential from 0 V to +0.5 V (vss. Cd/Cd2+ reference electrode) and they increase with increasing electrolyte concentration. The admittance of the electrode in pure PC (as received) is by 2 – 3 orders of magnitude smaller. Undoubtedly, the properties of ions in solution influence the capacity by a factor not exceeding 2 to 5