Showing papers by "Alex Schechter published in 1997"
TL;DR: In this paper, a comparative study of lithium and graphite electrodes in a large matrix of solvents, salts and additives is presented, showing an interesting correlation between the three-dimensional structure of graphite electrode, the diffusion coefficient of Li+ and their voltammetric behaviour in Li-intercalation processes.
424 citations
TL;DR: In this article, failure and stabilization mechanisms of Li−graphite electrodes were studied in model electrolyte systems, tetrahydrofuran (THF), propylene carbonate (PC), THF containing water contamination, and THF/PC solutions were used.
Abstract: The aim of this work was to study failure and stabilization mechanisms of Li−graphite electrodes. As model electrolyte systems, tetrahydrofuran (THF), propylene carbonate (PC), THF containing water contamination, and THF/PC solutions were used. A variety of electrode behavior can be observed in these solutions including reversible intercalation at high capacity, cyclability with deteriorating capacity, and in cases of dry THF and PC solutions, disability of Li intercalation. Chronopotentiometry, chronoamperometry, cyclic voltammetry impedance spectroscopy, electron microscopy, in situ and ex situ XRD, and surface sensitive FTIR spectroscopy were used in order to understand the reasons for the stability or failure of Li−graphite intercalation anodes. In PC and dry THF, massive solvent reduction occurs with a relatively low degree of electrode passivation. These processes change the electrode's morphology and electrically isolate carbon particles. At low concentration of water (>40 ppm) and PC (optimum 1 M)...
391 citations
TL;DR: In this article, the surface chemistry developed on lithium and carbon electrodes in MPC solutions was investigated in conjugation with electrochemical studies. And the results showed that the surface films produced on graphite were highly stable, allowing reversible Li-ion intercalation.
Abstract: Methyl propyl carbonate (MPC) solutions containing Li salts can be used as a single-solvent electrolyte with addition of ethylene carbonate (EC). Graphite electrodes can be cycled at high reversible capacity in MPC solutions containing LiPF{sub 6} and LiAsF{sub 6}. The use of acyclic, unsymmetric alkyl carbonate solvents, such as ethyl methyl carbonate (EMC) and MPC in Li-ion based electrolytes, increases the stability of the graphite electrode. Whereas a small amount of EC is still needed as cosolvent in EMC solutions to obtain stable surface films on graphite electrodes, the authors show here that the surface films produced on graphite in MPC solutions (without added EC) are highly stable, allowing reversible Li-ion intercalation. To understand this trend, they investigated the surface chemistry developed on lithium and carbon electrodes in MPC solutions in conjugation with electrochemical studies.
74 citations
TL;DR: In this article, surface sensitive FTIR spectroscopy, atomic force microscopy (AFM), electrochemical quartz crystal microbalance (EQCM) measurements were applied to Li and Li-graphite electrodes in a variety of electrolyte solutions of interest in conjunction with standard electrochemical techniques.
Abstract: This paper reports on some new results on the application of surface sensitive techniques for the study of the correlation of surface chemistry, morphology and electrochemical behavior of lithium and lithiated graphite as anodes for rechargeable batteries. Surface sensitive FTIR spectroscopy, atomic force microscopy (AFM), electrochemical quartz crystal microbalance (EQCM) were applied to Li and Li-graphite electrodes in a variety of electrolyte solutions of interest, in conjunction with standard electrochemical techniques. The similarity in the surface chemistry developed on Li and lithiated graphite in solutions is demonstrated and discussed. We demonstrate the strong impact of the surface chemistry on the morphology of Li deposition-dissolution processes, and the use of in situ EQCM measurements for the choice of optimal electrolyte solutions for rechargeable batteries with Li metal anodes.
1 citations