Laszlo Redey

High temperature lithium/sulfide batteries

Bipolar LiAl/FeS and LiAl/FeS2 batteries are being developed for electric vehicle (EV) applications by Argonne National Laboratory. Current technology employs a two-phase Li alloy negative electrode, low melting point LiCl—rich LiClLiBrKBr molten salt electrolyte, and either an FeS or an upper-plateau (UP) FeS2 positive electrode. These components are assembled in an “electrolyte-starved” bipolar cell configuration. Use of the two-phase Li alloy (α + β LiAl and Li5Al5Fe2) negative electrode provides in situ overcharge tolerance that renders the bipolar design viable. Employing LiCl rich LiClLiBrKBr electrolyte in “electrolyte-starved” cells achieves low-burdened cells that possess low area-specific impedance; comparable to that of flooded cells using LiClLiBrKBr eutectic electrolyte. The combination of dense U.P. FeS2 electrodes and low-melting electrolyte produces a stable and reversible couple, achieving over 1000 cycles in flooded cells, with high power capabilities. In addition, a family of stable chalcogenide ceramic/sealant materials was developed that produce high-strength bonds between a variety of metals and ceramics, which renders lithium/iron sulfide bipolar stacks practical. Bipolar LiAl/FeS and LiAl/FeS2 cells and four-cell stacks using these seals are being built and tested in the 13 cm diameter size for EV applications. To date, LiAl/FeS cells have achieved 240 W kg−1 power at 80% depth of discharge (DOD) and 130 Wh kg−1 energy at the 25 W kg−1 rate. LiAl/FeS2 cells have attained 400 W kg−1 power at 80% DOD and 180 Wh kg−1 energy at the 30 W kg−1 rate. When cell performance characteristics are used to model full-scale EV and hybrid vehicle (HV) batteries, they are projected to meet or exceed the performance requirements for a large variety of EV and HV applications.

Separation of Actinides from LWR Spent Fuel Using Molten-Salt-Based Electrochemical Processes

Abstract Results are presented of work done at Argonne National Laboratory to develop a molten-salt-based electrochemical technology for extracting uranium and transuranic elements from spent light water reactor fuel. In this process, the actinide oxides in the spent fuel are reduced using lithium at 650°C in the presence of molten LiCl, yielding the corresponding actinides and Li2O. The actinides are then extracted from the reduction product by means of electrorefining. Associated with the reduction step is an ancillary salt-recovery step designed to electrochemically reduce the Li2O concentration of the salt and recover the lithium metal. Experiments were performed at the laboratory scale (50 to 150 g of fuel and 0.5 to 3.5 l of salt) and engineering scale (3.7 to 5.2 kg of fuel and 50 l of salt). Laboratory-scale experiments were designed to obtain information on the fundamental factors affecting process rates. Engineering-scale experiments were conducted to verify that the parameters controlling process scaleup are sufficiently understood, and to test equipment and operating concepts at or near full scale. All indications are that the electrochemical-based process should be workable at practical plant sizes.

Morphological considerations of the nickel chloride electrodes for zebra batteries

Abstract Electrochemical and morphological investigations of various nickel chloride electrodes were carried out. Three different types of Nickel chloride electrodes were investigated in this study: a nonporous nickel substrate, a nickel felt, and a porous sintered electrode. It was observed that the nickel chloride layer formation during the charge limits the area capacity of solid nickel to 0.6 C/cm 2 . There is also a direct relationship between the electrochemical performance and morphological parameters of the nickel chloride electrode. The capacity trend of these electrodes was explained by considering both the surface area and the pore-size distribution necessary for an effective mass transport during charge and discharge reactions. A rational approach to fabricate electrodes with improved nickel utilization is also discussed.

Dynamic performance measurements of Na/NiCl2 cells for electric vehicle applications

Abstract A method to measure the dynamic-performance of sodium/nickel chloride research cells under various dynamic load profiles, such as the Simplified Federal Urban Driving Schedule (SFUDS) has been described. The dynamic performance of various Na/NiCl 2 research cells is measured in various power profiles in which the duration, intensity, and ratios of the power levels (mW/cm 2 ) in the SFUDS-like profiles are varied. Performance parameters such as area-specific impedance and specific-area energy are obtained by discharging these cells under actual conditions that exist in the full-size battery during the intended applications. The performance parameters measured by this method are employed in relatively simple scale-up calculations to project performances of full-size battery.

Molten salt electrolytes for high-temperature lithium cells

Abstract The composition and melting point of the molten salt electrolyte play a key role in the performance of high-temperature Li-alloy/metal sulfide cells. For example, the performance of the LiAl/FeS cell operated under flooded-electrolyte conditions improves markedly with an increase in the LiCl content of the LiClKCl electrolyte. A similar cell, when operated in a starved-electrolyte state, requires the use of an all-lithium cation electrolyte ( e.g. , LiFLiClLiBr) to achieve good performance. Both these electrolytes have fairly high melting points, >400 °C. The LiAl/FeS 2 cell, on the other hand, has been found to operate well as an upper-plateau cell in an electrolyte (25mol%LiCl–37mol%LiBr–38mol%KBr) with a low melting point, 310 °C. Recent laboratory investigations have also demonstrated that the LiAl/(NiFe)S 2 cell operates very well in an Li 2 S saturated, all-lithium, cation electrolyte at high temperatures, 475 °C.

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.

Chemical overcharge and overdischarge protection for Li-alloy/transition-metal sulfide cells

Chemical overcharge protection by a polysulfide-shuttle mechanism has been proposed for lithium-alloy-disulfide cells; for example, disulfide is FeS{sub 2}, FeS{sub 2}-NiS{sub 2} or FeS{sub 2}-CoS{sub 2}. This mechanism, however, cannot be applied to monosulfide (e.g., FeS) cells because the soluble polysulfide formation occurs at a much higher positive potential than the operational potential range of the monosulfide active material. For lithium-alloy/monosulfide cells, use of a controlled self-discharge process by the dissolved lithium as a means of chemical overcharge protection, has been developed and described in this article. The controlled self-discharge process, however, is not limited to the monosulfide cells. Because the protecting action is based on the negative electrode, this process is equally applicable to the mono- and disulfide cells. For the present experiments monosulfide cells were chosen to study the involved processes free from any interference of the polysulfide mechanisms.

Effect of chemical additives on the performance of Na/NiCl2 cells

The effect of chemical additives on the performance of sodium/nickel chloride cells was investigated in quasi-sealed laboratory research cells. The performance of these cells was measured by galvanostatic and galvanodynamic methods. It was observed that the use of sodium bromide, sulfur, sodium iodide, and a combination of these additives enhance the performance of the Na/NiCl2 cells by reducing the area-specific impedance of the nickel chloride electrode. Improved morphology by the use of the poreformer further improves the nickel utilization and the electrode impedance. The performance enhancement is attributed to the chemical and morphological modifications of the nickel chloride electrode in the Na/NiCl2 cells.

Calorimetric measurements on electrochemical cells with Pd-D cathodes

Two series of experiments were performed to determine the conditions of cell operation that produce sufficient excess heat to be useful for the production of energy. In the first series, the results from a differential temperature analysis of identical light- and heavy-water electrochemical cells were too ambiguous and, thus, not suitable for evaluating excess heat effects. In the second series, two Pd-D/LiOD-saturated D2O/Pt cells were operated at current densities between 12.5–500 mA/cm2 in a constant-heatloss-rate twin calorimeter for 460 hours. Water loss measurements during the experiments indicated that the recombination reaction (2D2 + O2 → 2D2O) did not occur. The D/Pd ratio was determined gravimetrically during the experiments. No excess heat was found within the sensitivity (0.13 W, 0.082 W/cm3 of Pd, 0.013 W/cm2 of Pd) and precision (±0.3 W) of the calorimeter.

A Miniature Glass‐Membrane Reference Electrode/Sensor for Na‐Activity Measurements in Molten Salts

The construction and performance of miniature reference electrode/sensor systems are described. The reference electrode/sensor is made from small-diameter alumina tubing and a sodium-ion-conductive glass membrane. The reference electrode/sensor has been used to measure thermodynamically defined sodium activity for the temperature range of 100/sup 0/-600/sup 0/C in many different electrochemical systems.