Andre Belanger

Assessment of Polymer‐Electrolyte Batteries for EV and Ambient Temperature Applications

The feasibility of polyether-based all-solid-state cells has been assessed in a joint research and development program. At 80/sup 0/-100/sup 0/C, cells using TiS/sub 2/ or V/sub 6/O/sub 13/ positive-electrode material and exces lithium show high material utilization at 0.5-1.0 mA/cm/sup 2/ and can be cycled more than 250 times. Furthermore, a new family of polyether electrolytes has been found that allows room temperature (26/sup 0/C) operation at 3-20 ..mu..A/cm/sup 2/.

Electrochemical modeling of lithium polymer batteries

An electrochemical model for lithium polymer cells was developed and a parameter set for the model was measured using a series of laboratory experiments. Examples are supplied to demonstrate the capabilities of the electrochemical model to obtain the concentration, current, and potential distributions in lithium polymer cells under complex cycling protocols. The modeling results are used to identify processes that limit cell performance and for optimizing cell design. Extension of the electrochemical model to examine two-dimensional studies is also described.

Large lithium polymer battery development The immobile solvent concept

Abstract The program to develop large lithium-metal, polymer electrolyte batteries for electric traction and stand-by power is reviewed. Dry polymer electrolyte conductivity improvement through research into polymers and lithijm salts has led to a thin-film lithium polymer battery that operates in the range of 60 to 40 °C. Recent developments in large lithium polymer cell design and production are given, including preliminary results on lithium polymer cell production for the US Advanced Battery Consortium (USABC). Results of stand-by and cycle-life tests on small laboratory cells over several years are also presented confirming the electrolytes exceptional stability in the lithium rechargeable-cell environment.

Solid‐State Detectors for the Potentiometric Determination of Gaseous Oxides II . Measurements in Oxygen‐Variable Gases in the , , , System

This paper describes an extended application of potentiometric solid-state detectors for measuring oxides in oxygen-variable gases. The SO/sub 2/, SO/sub 3/, O/sub 2/, Pt/SO/sub 4//sup 2 -/ system examined in Part I for oxide detection in air is studied here with respect to the total sulfur oxide and oxygen partial pressures. A study of the experimental parameters, operating temperatures, and the oxygen partial-pressure range revealed the possibility of a simple method of compensating the effect of the oxygen partial pressure on the signal from the oxide detector. An entirely solid-state device consisting of a potassium-sulfate oxide detector, a stabilized-zirconia oxygen detector, and usual electronic components is described, and results of tests with synthetic gas mixtures are presented. Experimental findings confirm calculations based on the electrode reactions and on the rapidly established equilibrium at the platinum electrode.

Hydrogen Evolution Reaction on Vanadium, Chromium, Manganese, Cobalt

The electrolytic hydrogen evolution reaction (HER) was studied on V, Cr, Mn, and Co in sulfuric acid-- sulfate solutions. The data consist of Tafel slopes, exchange current densities, apparent heats of activation, corrosion rates, corrosion potentials, and, in some cases, reaction order derivatives. Attempts were also made to obtain information on the electrode coverage by transient techniques. The presence of corrosion, however, makes the possible electrode coverage by adsorbed hydrogen inaccessible. By combining these electrode kinetic data with the gas-phase hydrogen adsorption behavior of these metals, it is suggested that the HER proceeds by means of the initial discharge mechanism on V and Mn whereas on Cr and Co, the radical-ion mechanism has been concluded. (auth)

The hydrogen evolution reaction on AgPd alloys: Influence of electronic properties on electroactivity

Abstract The hydrogen evolution reaction was studied on palladium, silver and several PdAg alloys. The electrochemical data consist of steady state potentiostatic current-potential measurements and charging curves aimed at determining the electrode coverage by chemisorbed hydrogen. The surface analyses of the electrode materials were carried out by X-ray diffraction, optical microscopy and Auger electron spectroscopy. The object of the work was to investigate the influence of electronic properties of the electrodes on their electrocatalytic activities. The exchange current densities show a maximum value and the apparent heat of activation a minimum value at alloy compositions containing about 60% Pd (atomic percentage on the surface). A break in the curve of the reversible potential versus alloy composition, for oxide-free surfaces, is also observed at this composition. This composition is different, however, from that at which the d band is filled in PdAg alloys, i.e. 40% Pd. This suggests a lack of direct relationship between electroactivity and percentage d character, as was previously concluded for the AuPt alloys by Breiter.

Electrochemical intercalation of lithium into carbons using a solid polymer electrolyte

Abstract A study of the electrochemical performance of carbon materials from different types was carried out on true solid polymer-based poly(ethylene oxide) (PEO) with LiTFSI for application as the negative electrode in lithium ion solid-state batteries (LISSBs) at 60 °C. The reversible and irreversible capacity depend strongly on the crystallinity, the form of carbon and the impurities. A comparison of particle versus fiber was done when we investigated the charge/discharge characteristics with different current densities. The galvanostatic curves show high reversibility of the lithium—carbon in solid polymer electrolyte. The kinetics of electrochemical intercalation of lithium into carbon was studied by impedance spectroscopy especially for evaluating the diffusion coefficient in different origins of carbon. The degree of ionization of lithium was investigated by using solid-state 7 Li nuclear magnetic resonance spectroscopy when the electrode is fully intercalated or doped down to 0 V. The chemical shift of 7 Li NMR in lithium intercalation or doping in the carbons was classified in two ranges, 42 ppm and 9 ppm. 7 Li NMR suggests the carbon with a 42 ppm range is the best choice for LISSBs.

The hydrogen evolution reaction on Ni-Sn alloys and intermetallics

Abstract Ni-Sn alloys containing 0%, 1.1%, 11.6%, 25.5%, 40.3%, 63.5%, 77.9%, 83.5%, 98% and 100% tin were prepared and examined regarding their activity towards the hydrogen evolution reaction in sulphuric acid solutions. The composition of these alloys and intermetallics was determined from the initial weight of the constituents used in the alloy preparation. The identification of various phases was carried out by X-ray diffraction analysis using ASTM standard microfiles. The surface composition of these alloys was determined by Auger electron spectroscopy for several typical cases, both before and after the cathodic polarization. The electrochemical measurements consisted of steady state potentiostatic polarization curves at various temperatures and potentiodynamic profiles. The electrochemical data deduced include Tafel slopes, exchange current densities, apparent heats of activation and potentiodynamic behaviour. On nickel and nickel-rich intermetallics, electrochemical desorption is indicated as the rate-determining step whereas the hydrogen evolution reaction appears to proceed by the initial dischange mechanism on tin and tin-rich alloys. Also the activity of nickel-rich intermetallics approaches that of nickel whereas the tin-rich alloys tend to exhibit activity similar to that of tin.

Toward standardizing the measurement of electrochemical properties of solid-state electrolytes in lithium batteries ☆

A brief discussion on transport measurements for lithium ion conducting polymer electrolytes is given. An engineering approach to obtain a complete set of transport and thermodynamic properties for a binary salt dissolved in a polymer electrolyte solvent is described. The technique is based on concentrated solution theory and requires a minimal amount of experimentation. Results from measurements on a representative polymer electrolyte system are given. The measured transport and thermodynamic properties of the polymer electrolyte are used to simulate the performance of symmetric Li/polymer/Li cells and compare to experimental data.

Electronic Effects in Chemisorption and Electrocatalysis of the Hydrogen Evolution Reaction

a volcano-type relationship predicted theoretically by Parsons and Gerischer. Following early suggestions by Dowden1 and Dilke, Maxted and Eley2, it is widely believed in the literature on heterogeneous catalysis3 and electrocatalysis4 that the catalytic activity of the transition metals arises from the presence of unfilled d-bands in them. This view-point seems to have originated from the observation that since the transition metals readily adsorb molecular gases in general whereas sp metals do not, the chemisorption requires specific interactions involving holes in the d-band. On the basis of critical examination of a large amount of evidence, Ehrlich5 has shown that this view-point is not sustained on closer analysis. He has pointed out,