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Electrochemical cell and negative electrode therefor. [Li-Al anode]

Description: A secondary electrochemical cell is described with the positive and negative electrodes separated by a molten salt electrolyte with the negative electrode comprising a particulate mixture of lithium-aluminum alloy and electrolyte and an additive selected from graphitized carbon, Raney iron or mixtures thereof. The lithium-aluminum alloy is present in the range of from about 45 to about 80% by volume of the negative electrode, and the electrolyte is present in an amount not less than about 10% by volume of the negative electrode. The additive of graphitized carbon is present in the range of from about 1 to about 10% by volume of the negative electrode, and the Raney iron additive is present in the range of from about 3 to about 10% by volume of the negative electrode.
Date: July 29, 1981
Creator: Kaun, T.D.
Partner: UNT Libraries Government Documents Department

New Li-alloy electrode for Li-alloy/metal sulfide cells

Description: The present invention relates to electrodes for use in secondary electrochemical cells. More particularly, it concerns a method of making a negative electrode composition, the electrode composition made thereby and the secondary electrochemical cell containing the electrode, wherein the negative electrode composition includes a lithium alloy including silicon and nickel.
Date: December 31, 1994
Creator: Kaun, T.D.
Partner: UNT Libraries Government Documents Department

Resistivity of bipolar plate materials at the cathode interface in molten carbonate fuel cells.

Description: Measurements of oxide scale resistivity for prospective bipolar plate materials in the molten carbonate fuel cell (MCFC) are coupled with observations of microstructural/compositional change over time. This work searches for a compromise to the high corrosion rate of Type 316L and the high oxide scale resistance of Type 310S. We tested a group of materials having chromium content ranging from 16 to 31 wt%, including Nitronic 50 and NKK, a Ni-Cr-Fe alloy. Chromium content was found to be the primary determinant of oxide scale composition. In the MCFC cathode compartment, stainless steels generally formed a duplex structure with an inner Cr-rich layer and an outer, Fe-rich layer. The composition of the inner Cr-rich layer was related to the base alloy and had a controlling effect on scale resistivity. Oxide scale resistivity was measured for two electrolyte compositions: Li/K and Li/Na carbonates. Changes in the physical/mechanical properties (spallation/cracking) in the oxide scale of Type 316L provided an understanding of its resistivity fluctuations over time.
Date: November 18, 1998
Creator: Kaun, T. D.
Partner: UNT Libraries Government Documents Department

A shuttle mechanism for molten-electrolyte lithium batteries

Description: The lithium-transport rates arising from a lithium shuttle mechanism (LSM) were examined by potentiometric control of a lithium-alloy electrode in a temperature range of 400 to 515{degrees}C in three electrolytes: LiCl-KCl, LiCl-LiBr-KBr, and LiF-LiCl-LiBr. Lithium transport in Li/FeS{sub x} cells by LSM was found to occur by diffusion of reduced lithium species across the separator layer, which was controlled by the Li-activity of the Li-alloy electrode. Solubility of lithium was strongly affected by electrolyte composition, especially K{sup +} content, which in turn regulated the lithium transport rate. As evidenced by LSM rates, the solubilized lithium would appear to form dimers (e.g. Li{sub 2}{sup +} or LiK{sup +}). The half-cell self-discharge rates, which were measured, correlate well with self-discharge rates in developmental cells ranging from 0.1 to 10 mA/cm{sup 2}. Innovative application of the LSM has led to the development of overcharge tolerant Li/FeS{sub x} cells. A bimodal self-discharge characteristic (a 20-fold increase toward the end of charge) results from a 150-250 mV step increase in lithium activity of a two-phase Li-alloy electrode (Li-Al plus Li-Al{sub 5}Fe{sub 2}). Three versions of the battery cell (100 cm{sup 2} separator area) have been demonstrated: LiAl+Li{sub 5}Al{sub 5}Fe{sub 2}(10% of capacity)/LiCl-LiBr-KBr(MgO)/FeS{sub 2}, as well as a FeS-type, (both operated at 400{degrees}C) and LiAl+Li{sub 5}Al{sub 5}Fe{sub 2}(10% of capacity)/LiF-LiCl-LiBr(MgO)/FeS (operated at 475{degrees}C). These cells exhibit a unique combination of overcharge capacity and extended trickle-charge tolerance at 2-5 mA/cm{sup 2}. Additionally, Li/FeS{sub 2} cells having overcharge tolerance have operated with stable performance for greater than 500 cycles. The overcharge tolerance rates are sufficient for battery cells to exhibit built-in charge/equalization capability by way of full-battery trickle charging.
Date: November 1, 1993
Creator: Kaun, T. D. & Nelson, P. A.
Partner: UNT Libraries Government Documents Department

Lithium-ferrate-based cathodes for molten carbonate fuel cells

Description: Argonne National Laboratory is developing advanced cathodes for pressurized operation of the molten carbonate fuel cell (MCFC) at approximately 650 degrees Centigrade. These cathodes are based on lithium ferrate (LiFeO[sub 2]) which is attractive because of its very low solubility in the molten (Li,K)[sub 2]CO[sub 3] electrolyte. Because of its high resistivity, LiFeO[sub 2] cannot be used as a direct substitute for NiO. Cation substitution is, therefore, necessary to decrease resistivity. The effect of cation substitution on the resistivity and deformation of LiFeO[sub 2] was determined. The substitutes were chosen because their respective oxides as well as LiFeO[sub 2] crystallize with the rock-salt structure.
Date: 1996-10~
Creator: Lanagan, M. T.; Wolfenstine, J.; Bloom, I.; Kaun, T. D. & Krumpelt, M.
Partner: UNT Libraries Government Documents Department

Non-segregating electrolytes for molten carbonate fuel cells

Description: Argonne National Laboratory is developing molten carbonate electrolyte compositions which have minimal segregation in the individual fuel cell and cell stack under an electric field. The approach is to characterize Li-Na carbonate mixtures in terms of their segregation properties in an electric field and, if necessary, to modify the observed segregation by adding Ba and Ca carbonates. Both non-segregating properties and MCFC test-cell performance show improvement as the lithium content is modified, up or down, from a baseline of 52/48 Li/Na. Results of gasket strip (20 V) screening studies, as well as those from cell tests, will be discussed.
Date: September 1, 1997
Creator: Kaun, T.D.; Bloom, I.D. & Krumpelt, M.
Partner: UNT Libraries Government Documents Department

Modification of LiCl-LiBr-KBr electrolyte for LiAl/FeS{sub 2} batteries

Description: The bipolar LiAl/FeS{sub 2} battery is being developed to achieve the high performance and long cycle life needed for electric vehicle application. The molten-salt (400 to 440 C operation) electrolyte composition for this battery has evolved to support these objectives. An earlier change to LiCl-LiBr-KBr electrolyte is responsible for significantly increased cycle life (up to 1,000 cycles). Recent electrolyte modification has significantly improved cell performance; approximately 50% increased power, with increased high rate capacity utilization. Results are based on power-demanding EV driving profile test at 600 W/kg. The effects of adding small amounts (1--5 mol%) of LiF and LiI to LiCl-LiBr-KBr electrolyte are discussed. By cyclic voltammetry, the modified electrolytes exhibit improved FeS{sub 2} electrochemistry. Electrolyte conductivity is little changed, but high current density (200 mA/cm{sup 2}) performance improved by approximately 50%. A specific feature of the LiI addition is an enhanced cell overcharge tolerance rate from 2.5 to 5 mA/cm{sup 2}. The rate of overcharge tolerance is related to electrolyte properties and negative electrode lithium activity. As a result, the charge balancing of a bipolar battery configuration with molten-salt electrolyte is improved to accept greater cell-to-cell deviations.
Date: June 1, 1996
Creator: Kaun, T.D.; Jansen, A.N.; Henriksen, G.L. & Vissers, D.R.
Partner: UNT Libraries Government Documents Department

Improved MCFC performance with Li/Na/Ba/Ca carbonate electrolyte.

Description: Earlier electrolyte segregation tests of Li/Na carbonate used chemical analysis such as inductively coupled plasma/atomic emission spectroscopy (ICP/AES) of matrix strips wetted with carbonate and exposed to 5- to 20-V potential gradients. A segregation factor was correlated to the Li/Na carbonate composition. While fairly substantial segregation occurs at the eutectic composition of 52% Li, it is minimal at 60% to 75% Li. Such lithium-rich Li/Na carbonates may not be practical because the melting points are too high (i.e., liquidus point is 625 C). By adding calcium and barium to the lithium/sodium carbonates, we were able to lower the melting point and maintain nonsegregating behavior. This work is directed at examining the long-term stability of the quaternary Li/Na/Ba/Ca electrolytes. Electrolyte optimization work evaluates Li/Na ratio and Ba/Ca level to improve cell performance at 320 mA/cm{sup 2} and reduce temperature sensitivity. A number of cells with quaternary Li/Na/Ba/Ca electrolytes ranging from 3 to 5% Ba/Ca have operated well with stable, long-term performance. Congruent melting carbonate is important for commercial development. The best so far is 3.5% Ba/Ca/Na/Li (3.5 mol%/3.5 mol% Ba/Ca) carbonate (m.p. 440 C). Performance at 160 mA/cm{sup 2} is increased up to 150mV as compared with the baseline cell containing the Li/Na eutectic composition. Life stability has been reproduced by a number of bench-scale MCFC test with operations of 2000-4300 h and the electrolyte composition across the matrix little changed.
Date: July 21, 1999
Creator: Centeno, C.-J.; Kaun, T. D.; Krumpelt, M. & Schoeler, A.
Partner: UNT Libraries Government Documents Department

Sulfide ceramics in molten-salt electrolyte batteries

Description: Sulfide ceramics are finding application in the manufacture of advanced batteries with molten salt electrolyte. Use of these ceramics as a peripheral seal component has permitted development of bipolar Li/FeS{sub 2} batteries. This bipolar battery has a molten lithium halide electrolyte and operates at 400 to 450C. Initial development and physical properties evaluations indicate the ability to form metal/ceramic bonded seal (13-cm ID) components for use in high-temperature corrosive environments. These sealants are generally CaAl{sub 2}S{sub 4}-based ceramics. Structural ceramics (composites with oxide or nitride fillers), highly wetting sealant formulations, and protective coatings are also being developed. Sulfide ceramics show great promise because of their relatively low melting point, high-temperature viscous flow, chemical stability, high-strength bonding, and tailored coefficients of thermal expansion. Our methodology of generating laminated metal/ceramic pellets (e.g., molybdenum/sulfide ceramic/molybdenum) with which to optimize materials formulation and seal processing is described.
Date: June 1, 1995
Creator: Kaun, T.D.; Hash, M.C. & Simon, D.R.
Partner: UNT Libraries Government Documents Department

Development of a high-rate, rechargeable bipolar LiAl/FeS{sub 2} battery

Description: Materials refinements have improved bipolar Li-Al/FeS{sub 2} batteries for power-demand applications. Current technology uses a two-phase Li-alloy cathode, LiCl-LiBr-KBr electrolyte, and an upper-plateau (UP) FeS{sub 2} anode for a battery operated at 440 C; the battery is in sealed bipolar form. The two-phase Li alloy ({alpha}+{beta} Li-Al and Li{sub 5}Al{sub 5}Fe{sub 2}) cathode provides in situ overcharge tolerance that makes the bipolar design viable. The use of LiCl-rich LiCl-LiBr-KBr electrolyte in ``electrolyte-starved`` cells achieves low-burdened cells with low area-specific impedance, with MgO powder separator. Combining dense UP FeS{sub 2} electrodes with a CuFeS{sub 2} additive and a LiI-modified electrolyte produces a stable and reversible couple, with high power capabilities. Long cycle life depends on peripheral seals for each cell in the bipolar stack. Seal composition is based on stable sulfide ceramic/sealant materials that produce strong bonds between metals and ceramics. Using these seals, bipolar Li-Al/FeS{sub 2} cells and four-cell stacks are being built and tested (25 Ah, 13-cm dia). Adding 5 mol% LiI to the electrolyte increased specific energy by 50% under a 140 W/kg, constant power C/1 rate and a 544 W/kg power pulse (8-s) schedule. Cell capacity under the high-power pulse-demand approximates the C/3 rate discharge capacity. Cell specific energy is 155 Wh/kg at the C/3 rate.
Date: June 1, 1996
Creator: Kaun, T.D.; Jansen, A.N.; Hash, M.C.; Prakash, J.; Turner, R.L. & Henriksen, G.L.
Partner: UNT Libraries Government Documents Department

Li-Alloy/FeS Cell Design and Analysis Report

Description: This report contains historical information on the Li-alloy/FeS system that will be useful in its future applications. This document includes the following: (1) the chemical and electrochemical reactions for the Li-alloy/FeS system, accomplishments in past cell development efforts, and performance attained by state-of-the-art cells vs performance goals; (2) detailed drawings of state-of-the-art cell designs, documentation of cell fabrication techniques, and comparisons of alternative types of cell components (such as BN felt vs MgO powder separators, stainless vs low-carbon steel cell housings) and fabrication techniques (such as charged vs uncharged electrodes); (3) results of post-test cell analyses, including cell failure mechanisms, electrode morphology and active material distribution, and in-cell corrosion rates; (4) data from trade-off studies between specific power and energy; (5) discussion of battery design considerations (e.g., volumetric energy density, battery charger, and high-efficiency thermal insulation); (6) results of cost studies, which include materials and manufacturing costs of cells and batteries and heating costs involved in battery operation; and (7) projections of cell designs having the greatest potential for meeting electric-vehicle performance requirements.
Date: July 1985
Creator: Gay, E. C.; Steunenberg, Robert K.; Miller, W. E.; Battles, J. E.; Kaun, T. D.; Martino, F. J. et al.
Partner: UNT Libraries Government Documents Department

Advanced Fuel Cell Development Progress Report: January-March 1984

Description: Quarterly report discussing fuel cell research and development work at Argonne National Laboratory (ANL). This report describes activitiesdirected toward seeking alternative cathode materials to NiO for molten carbonate fuel cells.
Date: January 1985
Creator: Pierce, Robert Dean; Baumert, B.; Claar, T. D.; Fousek, R. J.; Huang, H. S.; Kaun, T. D. et al.
Partner: UNT Libraries Government Documents Department

Advanced Fuel Cell Development Progress Report: April-June 1984

Description: Quarterly report discussing fuel cell research and development work at Argonne National Laboratory (ANL). These efforts have been directed toward seeking alternative cathode materials to NiO for molten carbonate fuel cells. Particular emphasis has been placed on studying the relationship between synthesis conditions and the resistivity of doped and undoped LiFeO2 and Li2 MnO3 and on achieving a better understanding of the crystalline defect structures of the thermodynamically stable phases.
Date: November 1984
Creator: Pierce, Robert Dean; Claar, T. D.; Dees, D. W.; Fousek, R. J.; Kaun, T. D.; Kucera, C. H. et al.
Partner: UNT Libraries Government Documents Department