Time filter

Source Type

Walkowiak M.,Central Laboratory of Batteries And Cells | Waszak D.,Central Laboratory of Batteries And Cells | Schroeder G.,Adam Mickiewicz University | Gierczyk B.,Adam Mickiewicz University
Journal of Solid State Electrochemistry | Year: 2010

This article reports the synthesis details and film-forming properties of 1,1,3,3-tetramethyl-1,3-bis(3-(ω-hexadecyloxy-deca(ethylenoxy)propyl) disiloxane, a new potential electrolyte additive/functional co-solvent for propylene carbonate (PC)-based Li-ion cells with graphitic anodes. Galvanostatic charge/discharge characteristics and scanning electron microscopy images provide direct evidence for the suppression of solvent intercalation and graphite exfoliation in the presence of the additive. In terms of irreversible capacity, the additive's efficiency is the highest for 15% weight ratio in the solvent mixture. Potentiodynamic measurements have revealed that disiloxane component undergoes irreversible reduction at potential significantly higher then PC decomposition. Energy dispersive spectroscopy analysis of graphite flake surfaces confirm that silicon species from the disiloxane decomposition are built in the passive layer. The reported compound may be considered as a basis for alternative cost-effective electrolyte compositions for low-temperature applications. © 2008 Springer-Verlag.


Urbaniak J.,Poznan University of Technology | Skowronski J.M.,Poznan University of Technology | Olejnik B.,Central Laboratory of Batteries And Cells
Journal of Solid State Electrochemistry | Year: 2010

In the present work, a simple method of preparation of FeCl 4 -- graphite intercalation compounds from HCl/FeCl 3 solution with the aid of chemical oxidant is presented. Based on X-ray diffraction measurements it was concluded, that stages 8, 6, and 5 FeCl 4 --graphite intercalation compounds were obtained. The compounds thus obtained were thermally treated to obtain Fe 2O 3-exfoliated graphite composites. The dispersion of Fe 2O 3 in the exfoliated graphite flakes was examined with the aid of the energy dispersive X-ray analysis combined with a scanning electron microscopy. Electrochemical behavior of electrodes was investigated in 6 M KOH solution. Electrochemical investigations proved the formation of FeOOH on the surface of exfoliated graphite during the anodic process. Besides, electrochemical investigations showed that the lower limit potential strongly affects the redox behavior of the Fe 2O 3-EG electrode. © Springer-Verlag 2010.


Sierczynska A.,Central Laboratory of Batteries And Cells | Lota K.,Central Laboratory of Batteries And Cells | Lota G.,Central Laboratory of Batteries And Cells | Lota G.,Poznan University of Technology
Journal of Power Sources | Year: 2010

Nickel hydroxide is used as an active material in positive electrodes of rechargeable alkaline batteries. The capacity of nickel-metal hydride (Ni-MH) batteries depends on the specific capacity of the positive electrode and utilization of the active material because of the Ni(OH)2/NiOOH electrode capacity limitation. The practical capacity of the positive nickel electrode depends on the efficiency of the conductive network connecting the Ni(OH)2 particle with the current collector. As β-Ni(OH) 2 is a kind of semiconductor, the additives are necessary to improve the conductivity between the active material and the current collector. In this study the effect of adding different carbon materials (flake graphite, multi-walled carbon nanotubes (MWNT)) on the electrochemical performance of pasted nickel-foam electrode was established. A method of production of MWNT special type of catalysts had an influence on the performance of the nickel electrodes. The electrochemical tests showed that the electrode with added MWNT (110-170 nm diameter) exhibited better electrochemical properties in the chargeability, specific discharge capacity, active material utilization, discharge voltage and cycling stability. The nickel electrodes with MWNT addition (110-170 nm diameter) have exhibited a specific capacity close to 280 mAh g-1 of Ni(OH)2, and the degree of active material utilization was ∼96%. © 2010 Elsevier B.V.


Lota G.,Poznan University of Technology | Tyczkowski J.,Technical University of Lodz | Kapica R.,Technical University of Lodz | Lota K.,Central Laboratory of Batteries And Cells | Frackowiak E.,Poznan University of Technology
Journal of Power Sources | Year: 2010

The carbon material was modified by RF plasma with various reactive gases: O2, Ar and CO2. Physicochemical properties of the final carbon products were characterized using different techniques such as gas adsorption method and XPS. Plasma modified materials enriched in oxygen functionalities were investigated as electrodes for supercapacitors in acidic medium. The electrochemical measurements have been carried out using cyclic voltammetry, galvanostatic charge/discharge and impedance spectroscopy. The electrochemical measurements have confirmed that capacity characteristics are closely connected with a type of plasma exposition. Modification processes have an influence on the kind and amount of surface functional groups in the carbon matrix. The moderate increase of capacity of carbon materials modified by plasma has been observed using symmetric two-electrode systems. Whereas investigations made in three-electrode system proved that the suitable selection of plasma modification parameters allows to obtain promising negative and positive electrode materials for supercapacitor application. © 2009 Elsevier B.V.


Zalas M.,Adam Mickiewicz University | Walkowiak M.,Central Laboratory of Batteries And Cells | Schroeder G.,Adam Mickiewicz University
Journal of Rare Earths | Year: 2011

Modified with gadolinium-containing layer, nanoporous titania electrode and its application in dye-sensitized solar cells were reported. The electrode prepared was characterized with UV-Vis and X-ray diffraction (XRD) techniques. The amount of gadolinium was measured with inductively coupled plasma-optical emission spectrometry (ICP-OES) experiments. The modified electrode showed reduced N3 dye adsorption ability, but increased light conversion efficiency in comparison with the non-modified electrode. The overall conversion efficiencies, determined under 400 W/m2 irradiation with tungsten-halogen lamp at room temperature, were 0.55 for non-modified and 0.74 for modified electrodes. © 2011 The Chinese Society of Rare Earths.


Lota G.,Poznan University of Technology | Lota G.,Central Laboratory of Batteries And Cells | Milczarek G.,Poznan University of Technology
Electrochemistry Communications | Year: 2011

Two types of carbonaceous materials of different specific surface areas (835 and 1901 m2 g-1) were used as electrode materials in electrochemical capacitors and their performance was investigated in 1 mol L-1 H2SO4 with and without addition of two lignosulfonates of different molecular masses (8000 and 42,700 g mol -1). Measurements of 2-electrode cells confirmed that lignosulfonates as electrolyte additives increase the overall capacity of the supercapacitor of up to 33%. Moreover, for the electrolyte with lignosulfonates the charge propagation was facilitated, implying its capability of working at heavy duty regimes. Cycleability tests confirmed the absence of any significant effect of lignosulfonate additions to the electrolyte on supercapacitor durability. The relative capacitance change after 5000 cycles of galvanostatic charge/discharge at 1 A g-1 was ca. + 4.5% for less porous carbon and - 4.2% for more porous carbon, respectively. Furthermore, the investigations carried out in a 3-electrode configuration proved that a lignosulfonate addition to the electrolyte gives rise to the development of a reversible redox system on the positive electrode, due to the deposition of a thin lignosulfonate-derived film showing substantial redox activity assignable to quinone-type moieties. © 2011 Elsevier B.V.


Walkowiak M.,Central Laboratory of Batteries And Cells
International Journal of Electrochemical Science | Year: 2011

It has been demonstrated that pre-treatment (impregnation) of graphite anodes in a polyether functionalized disiloxane agent prevents graphite flake exfoliation and electrode degradation in Li-ion cells with electrolytes based on propylene carbonate (PC) as single electrolyte solvent. This beneficial effect has been evidenced to strongly depend on the concentration of the impregnation bath. For 100% concentration (pure siloxane), SEM images do not exhibit visible signs of flake splitting and the corresponding galvanostatic charge/discharge curves exhibit conventional lithium intercalation behavior, with reversible capacity approaching 300 mAh g-1. Post-mortem EDX analysis of cycled electrodes revealed the presence of silicon species in the passive layers on graphite. The proposed approach can be regarded as alternative for conventional exfoliation-suppressing methods relying on bulk electrolyte additives. © 2011 by ESG.


Wasinski K.,Central Laboratory of Batteries And Cells | Walkowiak M.,Central Laboratory of Batteries And Cells | Lota G.,Central Laboratory of Batteries And Cells | Lota G.,Poznan University of Technology
Journal of Power Sources | Year: 2014

Novel electrolyte additive for electrochemical capacitors has been reported. It has been demonstrated for the first time that addition of humic acids (HA) to KOH-based electrolyte significantly increases capacitance of symmetrical capacitors with electrodes made of activated carbon. Specific capacitances determined by means of galvanostatic charge/discharge, cyclic voltammetry and electrochemical impedance spectroscopy consistently showed increases for HA concentrations ranging from 2% w/w up to saturated solution with maximum positive effect observed for 5% w/w of the additive. The capacitance increase has been attributed to complex faradaic processes involving oxygen-containing groups of HA molecules. Due to abundant resources, low cost and easy processability the reported solution can find application in electrochemical capacitor technologies. © 2014 Elsevier B.V. All rights reserved.


Zalewska A.,Warsaw University of Technology | Walkowiak M.,Central Laboratory of Batteries And Cells | Niedzicki L.,Warsaw University of Technology | Jesionowski T.,Poznan University of Technology | Langwald N.,Warsaw University of Technology
Electrochimica Acta | Year: 2010

The aim of the presented work was to perform a preliminary study of the physicochemical and interfacial properties of hybrid organic-inorganic gel electrolytes for Li-ion batteries based on the PVdF/HFP polymeric matrix and surface-modified silicas. Two types of silica fillers of different grain sizes (>500 nm and ∼100 nm) were used as additives. The silica particles were modified by two different functional groups, i.e. methacryloxy and vinyl ones. The gel electrolytes based on PVdF/HFP copolymer were prepared according to the so-called Bellcore two-step process. The motivation of the present work was to study more deeply those systems in terms of morphology by means of scanning electron microscopy techniques. Fillers modified with identical functional groups but differing fundamentally in the manufacturing processes were compared in terms of the impact on morphology and electrochemical performance of the resulting membranes. Interfacial properties were examined by means of impedance spectroscopy technique using Swagelok-type cells with two lithium electrodes. © 2009 Elsevier Ltd. All rights reserved.


Grzeczka G.,Polish Naval Academy | Swoboda P.,Central Laboratory of Batteries And Cells
Solid State Phenomena | Year: 2015

The most commonly used starter batteries for ship engine rooms are lead acid systems. Lead acid batters have the lowest electrochemical parameters from all other modern electrochemical systems. On the other hand their biggest advantage is the price of the cell which is much lower comparing to other electrochemical systems. Due to fact that the lithium – ion batteries are very widely used and constantly developed this technology is starting to be promising as an alternative for lead acid batteries for starter applications. Because of this there is a need to verify if the lithium-ion technology can be used for start-up and power backup systems and how will it affect the construction of the engine room and those systems. In order to determine the potential energetic requirements during the design of starter systems in an backup engine room with the use of lithium – ion batteries, in the article the analytic of their performance was conducted with comparison of other electrochemical systems. © (2015) Trans Tech Publications, Switzerland.

Loading Central Laboratory of Batteries And Cells collaborators
Loading Central Laboratory of Batteries And Cells collaborators