Use In Lithium-ion Cells Research Articles

Cell design for the electrodeposition of polyacrylonitrile onto graphite composite electrodes for use in lithium-ion cells

Polyacrylonitrile (PAN) is among the most common polymer materials in the world thanks to its versatility in a wide range of applications. Of importance to this work is its use in electrochemical cells. PAN has seen use as a separator material and as a binder material in lithium-ion cells. Expanding upon innovations made in recent decades for electrodepositing PAN onto conductive surfaces, this work details methods used to apply PAN as a thin coating to graphite composite electrodes; the resultant films may then be used for further electrochemical analysis in a lithium-ion cell. Graphite electrodes coated with electrodeposited PAN films were produced of a practical size for electrochemical testing in Swagelok cells; optical microscopy images of the resulting PAN coated graphite electrodes were also recorded to study the morphology of the coating.

(Invited) Design and Development of Novel Electrolytes for Batteries and Supercapacitors

Electrolytes are often forgotten parts of batteries and super capacitors compared to numerous review papers and textbooks describing properties of electrode materials. The intention of the present work is to fill the gap and bring electrolytes to the attention of the scientists working in the field of electrochemical energy conversion and storage devices. New challenges appearing on the nowadays battery and super caps market force researchers to design novel electrolytes often baring features not found in up to date studied systems. These challenges are aimed to be addresses and discussed. In the present work three types of electrolytes for application in modern batteries or super caps will be presented and discussed.Strategy on design of new Huckel type anions for electrolyte salts is presented in the context given by the review of legacy and state-of-the-art systems. Synthesis, conditions for handling, stability and electrochemical parameters of salts used or with a potential for use in lithium-ion cells are described. Effect of solvent mixtures, selection strategy of salts and solvents for battery mixtures for maximization of chosen parameters or for given application is explained.We are going to show how crystallographic studies allow for a better understanding of electrochemical properties of Huckel type salts. Comprehensive structure analysis of crystalline materials reveals valuable information about coordination ability of anions and provides the basis to develop the model of poly (ethylene oxide) electrolytes and liquid systems. Results revealing new aggregation modes at high concentrations of lithium salts involving releasing cations by self-assembly of anionic sub network will be presented.The discovering and understanding the phenomena related to the organization of such systems in the solid state is crucial for the elaboration of novel electrolytes and gives information about cation and anion coordination in electrolytes.Also we are going to present novel hybrid polymeric electrolytes with unmodified and surface modified fillers based on silica, alumina and titania of different grain size. Special emphasize will be put on proper choice of the filler leading to preparation of composite system with enhance conductivities and lithium cation transference number compared to unmodified polymeric electrolytes.At the end we are going to discuss properties of several proton conducting gel polymeric electrolytes with various solvent ratios, to be used as electrolytes in super capacitor applications. The influence of the gel composition on the ionic conductivity, temperature behavior and electrochemical properties has been studied in a large temperature range (-40 to 80 °C)..

Development and Use of a Lithium-Metal Reference Electrode in Aging Studies of Lithium-Ion Batteries

The development and implementation of an in situ lithium-metal reference electrode for use in lithium-ion cells is described. The reference electrode is inserted into cylindrical, commercially available 1.2 Ah lithium-ion cells via perforation of the cell's outer metallic casing. The reference electrode is used to investigate voltage characteristics of the individual electrodes throughout calendar (i.e., zero duty) aging and duty cycle aging regimes. The response of the electrode voltages (vs. reference) to a given current pulse prior to and during interruptions of the aging regime indicates that the resistance of the positive-electrode is much larger than that of the negative electrode. Prior to aging, the ratio of the positive electrode resistance to that of the negative electrode is approximately two. After aging, the resistance of the positive electrode nearly triples, resulting in a ratio of approximately six, with the resistance of the negative electrode remaining approximately unchanged for both calendar- and cycle-aging regimes. The changes in the cell's coulombic capacity at various discharge rates are also characterized and indicate the additional contribution of cycle aging over the calendar aging alone to the capacity loss of cells. Furthermore, both “charge depletion” and “charge sustaining” cycle aging were investigated and indicates the added stress of charge depletion operation.

Electrochemistry of NaK 2C 12 in lithium-containing electrolytes and its use in lithium-ion cells ☆

The electrochemistry of NaK 2C 12 in 1 M LiClO 4 EC-DMC solutions has been studied. The results show that, upon oxidation, NaK 2C 12 irreversibly releases one mole of potassium ions. The resulting composite electrode, that appears to be a mixture of graphite and Na–K alloy, is capable to reversibly intercalate lithium up to LiC 6 with fast rate. The compound can be used in lithium-ion cells with partially lithiated cathodes such as LiMn 2O 4, resulting in a two plateaus cell operating in the Li 1+ x Mn 2O 4 and Li 1− x Mn 2O 4 regions.