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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Evaluation of lithium alloy anode materials for Li-TiS2 cells

A study was performed to select candidate lithium alloy anode materials and establish selection criteria. Some of the selected alloy materials were evaluated for their electrochemical properties and performance. This paper describes the criteria for the selection of alloys and the findings of the studies. Li-Si and Li-Cd alloys have been found to be unstable in the EC+2-MeTHF-based electrolyte. The Li-Al alloy system was found to be promising among the alloy systems studied in view of its stability and reversibility. Unfortunately, the large volume changes of LiAl alloys during charge/discharge cycling cause considerable 'exfoliation' of its active mass. This paper also describes ways how to address this problem. The rate of disintegration of this anode would probably be surpressed by the presence of an inert solid solution or a uniform distribution of precipitates within the grains of the active mass. It was discovered that the addition of a small quantity of Mn may improve the mechanical properties of LiAl. In an attempt to reduce the Li-Al alloy vs. Li voltage, it was observed that LiAlPb(0.1)Cd(0.3) material can be cycled at 1.5 mA/sq cm without exfoliation of the active mass.

Huang, C.-K.↗
NASA NTRS1986

Examination of design options for 35 Ah ambient temperature Li-TiS sub 2 cells

The Jet Propulsion Laboratory is actively engaged in the development of ambient temperature rechargable lithium cells for future NASA geosynchronous Earth orbit (GEO) missions. To achieve these ambitious goals, Li-TiS2, Li-MoS3, and Li-V6O13 systems were examined in detail. Among these three, the Li-TiS2 system has shown the longest life cycle and highest rate capability. Experimental Li-TiS2 batteries (10.5 V, 0.4 Ah) developed in-house have completed eight simulated and accelerated GEO seasons successfully. Inview of the encouraging results, the design options were examined for a scaled-up Li-TiS2 cell. It is hoped that the results of these studies will provide guidelines for prioritizing the research efforts and guiding the selection of optimized materials. Designs for 35 Ah Li-TiS2 cell were examined because present day geosynchronous satellites are powered by batteries of 35 Ah capacity. A computer program was developed to evaluate the influence of various design parameters on the specific energy and the rate capability of the cells.

Shen, D. H.↗
NASA NTRS1989

Advances in ambient temperature secondary lithium cells

The Jet Propulsion Laboratory is involved in a Research and Development program sponsored by NASA/OAST on the development of ambient temperature secondary lithium cells for future space applications. Some of the projected applications are planetary spacecraft, planetary rovers, and astronaut equipment. The main objective is to develop secondary lithium cells with greater than 100 Wh/kg specific energy while delivering 1000 cycles at 50 percent Depth of Discharge (DOD). To realize these ambitious goals, the work was initially focused on several important basic issues related to the cell chemistry, selection of cathode materials and electrolytes, and component development. The performance potential of Li-TiS2, Li-MoS3, Li-V6O13 and Li-NbSe3 electrochemical systems was examined. Among these four, the Li-TiS2 system was found to be the most promising system in terms of realizable specific energy and cycle life. Some of the major advancements made so far in the development of Li-TiS2 cells are in the areas of cathode processing technology, mixed solvent electrolytes, and cell assembly. Methods were developed for the fabrication of large size high performance TiS2 cathodes. Among the various electrolytes examined, 1.5M LiAsF6/EC + 2-MeTHF mixed solvent electrolyte was found to be more stable towards lithium. Experimental cells activated with this electrolyte exhibited more than 300 cycles at 100 percent Depth of Discharge. Work is in progress in other areas such as selection of lithium alloys as candidate anode materials, optimization of cell design, and development of 5 Ah cells. The advances made at the Jet Propulsion Laboratory on the development of secondary lithium cells are summarized.

Subbarao, S.↗
DOE OSTI2020

Materials Data on Ti3(SeS2)2 by Materials Project

TiS2(TiSeS)2 is trigonal omega-derived structured and crystallizes in the trigonal P3m1 space group. The structure is two-dimensional and consists of one TiS2 sheet oriented in the (0, 0, 1) direction and two TiSeS sheets oriented in the (0, 0, 1) direction. In the TiS2 sheet, Ti4+ is bonded to six S2- atoms to form edge-sharing TiS6 octahedra. There are three shorter (2.44 Å) and three longer (2.45 Å) Ti–S bond lengths. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted T-shaped geometry to three equivalent Ti4+ atoms. In the second S2- site, S2- is bonded in a distorted T-shaped geometry to three equivalent Ti4+ atoms. In each TiSeS sheet, Ti4+ is bonded to three equivalent Se2- and three equivalent S2- atoms to form edge-sharing TiSe3S3 octahedra. All Ti–Se bond lengths are 2.59 Å. All Ti–S bond lengths are 2.41 Å. Se2- is bonded in a 3-coordinate geometry to three equivalent Ti4+ atoms. S2- is bonded in a distorted T-shaped geometry to three equivalent Ti4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ti4S8N by Materials Project

(TiS2)8N2 is trigonal omega-derived structured and crystallizes in the monoclinic Pm space group. The structure is two-dimensional and consists of one ammonia molecule and two TiS2 sheets oriented in the (0, 0, 1) direction. In each TiS2 sheet, Ti+3.75+ is bonded to six S2- atoms to form edge-sharing TiS6 octahedra. There are three shorter (2.42 Å) and three longer (2.44 Å) Ti–S bond lengths. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted T-shaped geometry to three equivalent Ti+3.75+ atoms. In the second S2- site, S2- is bonded in a distorted T-shaped geometry to three equivalent Ti+3.75+ atoms. In the third S2- site, S2- is bonded in a distorted T-shaped geometry to three equivalent Ti+3.75+ atoms. In the fourth S2- site, S2- is bonded in a distorted T-shaped geometry to three equivalent Ti+3.75+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiTiS2O by Materials Project

Li2O2(TiS2)2 crystallizes in the trigonal R3m space group. The structure is two-dimensional and consists of three Li2O2 sheets oriented in the (0, 0, 1) direction and three TiS2 sheets oriented in the (0, 0, 1) direction. In each Li2O2 sheet, Li1+ is bonded in a trigonal planar geometry to three equivalent O2- atoms. All Li–O bond lengths are 1.95 Å. O2- is bonded in a trigonal planar geometry to three equivalent Li1+ atoms. In each TiS2 sheet, Ti4+ is bonded to six S+1.50- atoms to form edge-sharing TiS6 octahedra. There are three shorter (2.41 Å) and three longer (2.43 Å) Ti–S bond lengths. There are two inequivalent S+1.50- sites. In the first S+1.50- site, S+1.50- is bonded in a 3-coordinate geometry to three equivalent Ti4+ atoms. In the second S+1.50- site, S+1.50- is bonded in a 3-coordinate geometry to three equivalent Ti4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ti5MnS10 by Materials Project

Ti2MnS4(TiS2)3 is trigonal omega-derived structured and crystallizes in the trigonal P-3m1 space group. The structure is two-dimensional and consists of one Ti2MnS4 sheet oriented in the (0, 0, 1) direction and three TiS2 sheets oriented in the (0, 0, 1) direction. In the Ti2MnS4 sheet, Ti+3.60+ is bonded to six S2- atoms to form TiS6 octahedra that share corners with six equivalent MnS6 octahedra, edges with six equivalent TiS6 octahedra, and a faceface with one MnS6 octahedra. The corner-sharing octahedral tilt angles are 47°. There are three shorter (2.41 Å) and three longer (2.52 Å) Ti–S bond lengths. Mn2+ is bonded to six equivalent S2- atoms to form MnS6 octahedra that share corners with twelve equivalent TiS6 octahedra, edges with six equivalent MnS6 octahedra, and faces with two equivalent TiS6 octahedra. The corner-sharing octahedral tilt angles are 47°. All Mn–S bond lengths are 2.48 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded to three equivalent Ti+3.60+ and three equivalent Mn2+ atoms to form a mixture of distorted corner and edge-sharing STi3Mn3 pentagonal pyramids. In the second S2- site, S2- is bonded in a distorted T-shaped geometry to three equivalent Ti+3.60+ atoms. In each TiS2 sheet, Ti+3.60+ is bonded to six S2- atoms to form edge-sharing TiS6 octahedra. There are three shorter (2.43 Å) and three longer (2.44 Å) Ti–S bond lengths. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted T-shaped geometry to three equivalent Ti+3.60+ atoms. In the second S2- site, S2- is bonded in a distorted T-shaped geometry to three equivalent Ti+3.60+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ti4MnS8 by Materials Project

Ti2MnS4(TiS2)2 crystallizes in the trigonal P-3m1 space group. The structure is two-dimensional and consists of one Ti2MnS4 sheet oriented in the (0, 0, 1) direction and two TiS2 sheets oriented in the (0, 0, 1) direction. In the Ti2MnS4 sheet, Ti+3.50+ is bonded to six S2- atoms to form TiS6 octahedra that share corners with six equivalent MnS6 octahedra, edges with six equivalent TiS6 octahedra, and a faceface with one MnS6 octahedra. The corner-sharing octahedral tilt angles are 47°. There are three shorter (2.42 Å) and three longer (2.52 Å) Ti–S bond lengths. Mn2+ is bonded to six equivalent S2- atoms to form MnS6 octahedra that share corners with twelve equivalent TiS6 octahedra, edges with six equivalent MnS6 octahedra, and faces with two equivalent TiS6 octahedra. The corner-sharing octahedral tilt angles are 47°. All Mn–S bond lengths are 2.46 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded to three equivalent Ti+3.50+ and three equivalent Mn2+ atoms to form a mixture of distorted edge and corner-sharing STi3Mn3 pentagonal pyramids. In the second S2- site, S2- is bonded in a distorted T-shaped geometry to three equivalent Ti+3.50+ atoms. In each TiS2 sheet, Ti+3.50+ is bonded to six S2- atoms to form edge-sharing TiS6 octahedra. All Ti–S bond lengths are 2.44 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted T-shaped geometry to three equivalent Ti+3.50+ atoms. In the second S2- site, S2- is bonded in a distorted T-shaped geometry to three equivalent Ti+3.50+ atoms.

36 MATERIALS SCIENCE↗
NASA NTRS1983

Elastomeric binders for electrodes

The poor mechanical integrity of the cathode represents an important problem which affects the performance of ambient temperature secondary lithium cells. Repeated charge of a TiS2 cathode may give rise to stresses which disturb the electrode structure and can contribute to capacity loss. An investigation indicates that the use of an inelastic binder material, such as Teflon, aggravates the problem, and can lead to electrode disruption and poor TiS2 particle-particle contact. The feasibility of a use of elastomers as TiS2 binder materials has, therefore, been explored. It was found that elastomeric binders provide an effective approach for simplifying rechargeable cathode fabrication. A pronounced improvement in the mechanical integrity of the cathode structure contributes to a prolonged cycle life.

Yen, S. P. S.↗
NASA NTRS1989

Advances in ambient temperature secondary lithium cells

The goal is to develop secondary lithium cells with a 100 Wh/kg specific energy capable of 1000 cycles at 50 percent DOD. The approach towards meeting this goal initially focused on several basic issues related to the cell chemistry, selection of cathode materials and electrolytes and component development. The performance potential of Li-TiS2, Li-MoS3, Li-V6O13 and Li-NbSe3 electrochemical systems was examined. Among these four, the Li-TiS2 system was found to be the most promising system in terms of achievable specific energy and cycle life. Major advancements to date in the development of Li-TiS2 cells are in the areas of cathode processing technology, mixed solvent electrolytes, and cell assembly. A summary is given of these advances.

Subbarao, S.↗
DOE OSTI2020

Materials Data on LiTi(SO)2 by Materials Project

LiO2TiS2 crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of one LiO2 sheet oriented in the (0, 0, 1) direction and one TiS2 sheet oriented in the (0, 0, 1) direction. In the LiO2 sheet, Li1+ is bonded to six equivalent O2- atoms to form edge-sharing LiO6 octahedra. There are four shorter (1.91 Å) and two longer (2.51 Å) Li–O bond lengths. O2- is bonded in a 4-coordinate geometry to three equivalent Li1+ and one O2- atom. The O–O bond length is 1.37 Å. In the TiS2 sheet, Ti3+ is bonded to six equivalent S atoms to form edge-sharing TiS6 octahedra. There are two shorter (2.42 Å) and four longer (2.46 Å) Ti–S bond lengths. S is bonded in a distorted T-shaped geometry to three equivalent Ti3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TiS2N by Materials Project

STiNS is trigonal omega-derived structured and crystallizes in the trigonal R3m space group. The structure is two-dimensional and consists of three ammonia molecules and three TiS2 sheets oriented in the (0, 0, 1) direction. In each TiS2 sheet, Ti3+ is bonded to six equivalent S2- atoms to form edge-sharing TiS6 octahedra. All Ti–S bond lengths are 2.43 Å. S2- is bonded in a distorted T-shaped geometry to three equivalent Ti3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiTi(SO)2 by Materials Project

LiO2TiS2 crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of one LiO2 sheet oriented in the (0, 0, 1) direction and one TiS2 sheet oriented in the (0, 0, 1) direction. In the LiO2 sheet, Li1+ is bonded to six equivalent O2- atoms to form edge-sharing LiO6 octahedra. There are four shorter (1.91 Å) and two longer (2.56 Å) Li–O bond lengths. O2- is bonded in a 4-coordinate geometry to three equivalent Li1+ and one O2- atom. The O–O bond length is 1.38 Å. In the TiS2 sheet, Ti3+ is bonded to six equivalent S atoms to form edge-sharing TiS6 octahedra. There are two shorter (2.42 Å) and four longer (2.46 Å) Ti–S bond lengths. S is bonded in a distorted T-shaped geometry to three equivalent Ti3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ti5S8 by Materials Project

Ti5S8 crystallizes in the trigonal R3m space group. The structure is two-dimensional and consists of three Ti3S4 sheets oriented in the (0, 0, 1) direction and six TiS2 sheets oriented in the (0, 0, 1) direction. In each Ti3S4 sheet, there are three inequivalent Ti+3.20+ sites. In the first Ti+3.20+ site, Ti+3.20+ is bonded to six S2- atoms to form a mixture of edge, face, and corner-sharing TiS6 octahedra. The corner-sharing octahedral tilt angles are 45°. There are three shorter (2.41 Å) and three longer (2.54 Å) Ti–S bond lengths. In the second Ti+3.20+ site, Ti+3.20+ is bonded to six S2- atoms to form a mixture of edge and corner-sharing TiS6 octahedra. The corner-sharing octahedral tilt angles are 3°. There are three shorter (2.42 Å) and three longer (2.47 Å) Ti–S bond lengths. In the third Ti+3.20+ site, Ti+3.20+ is bonded to six S2- atoms to form a mixture of edge, face, and corner-sharing TiS6 octahedra. The corner-sharing octahedra tilt angles range from 3–45°. There are three shorter (2.38 Å) and three longer (2.58 Å) Ti–S bond lengths. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded to six Ti+3.20+ atoms to form a mixture of distorted edge and corner-sharing STi6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 6°. In the second S2- site, S2- is bonded in a distorted T-shaped geometry to three equivalent Ti+3.20+ atoms. In the third S2- site, S2- is bonded in a distorted T-shaped geometry to three equivalent Ti+3.20+ atoms. In the fourth S2- site, S2- is bonded to six Ti+3.20+ atoms to form a mixture of edge and corner-sharing STi6 octahedra. In each TiS2 sheet, Ti+3.20+ is bonded to six S2- atoms to form edge-sharing TiS6 octahedra. All Ti–S bond lengths are 2.43 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted T-shaped geometry to three equivalent Ti+3.20+ atoms. In the second S2- site, S2- is bonded in a distorted T-shaped geometry to three equivalent Ti+3.20+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ZrTiS4 by Materials Project

ZrS2TiS2 is trigonal omega-derived structured and crystallizes in the trigonal P-3m1 space group. The structure is two-dimensional and consists of one TiS2 sheet oriented in the (0, 0, 1) direction and one ZrS2 sheet oriented in the (0, 0, 1) direction. In the TiS2 sheet, Ti4+ is bonded to six equivalent S2- atoms to form edge-sharing TiS6 octahedra. All Ti–S bond lengths are 2.47 Å. S2- is bonded in a distorted T-shaped geometry to three equivalent Ti4+ atoms. In the ZrS2 sheet, Zr4+ is bonded to six equivalent S2- atoms to form edge-sharing ZrS6 octahedra. All Zr–S bond lengths are 2.56 Å. S2- is bonded in a distorted T-shaped geometry to three equivalent Zr4+ atoms.

36 MATERIALS SCIENCE↗
NASA NTRS1980

Moderate temperature sodium cells. I - Transition metal disulfide cathodes

TiS2, VS2, and Nb(1.1)S2 transition metal disulfides were evaluated as cathode materials for a moderate temperature rechargeable Na cell operating at 130 C. The 1st discharge of TiS2 results in a capacity of 0.85 eq/mole; approximately half of the Na in the 1st phase spanning the Na range from zero to 0.30 and almost all the Na in the 2nd phase spanning the 0.37 to 0.80 range are rechargeable. VS2 intercalates up to one mole of Na/mole of VS2 in the 1st discharge; the resulting Na(x)VS2 ternary consists of 3 phases in the 3 ranges of Na from zero to 1. Niobium disulfide undergoes a phase change in the 1st discharge; the average rechargeable capacity in extended cycling of this cathode is 0.50 eq/mole.

Abraham, K. M.↗
NASA NTRS1984

Charge Control Investigation of Rechargeable Lithium Cells

An ambient temperature rechargeable Li-TiS2 cell was cycled under conditions which simulate aerospace applications. A novel charge/discharge state-of-charge control scheme was used, together with tapered current charging, to overcome deleterious effects associated with end-of-charge and end-of-discharge voltages. The study indicates that Li-TiS2 cells hold promise for eventual synchronous satellite-type applications. Problem areas associated with performance degradation and reconditioning effects are identified.

Otzinger, B.↗
NASA NTRS1988

Evaluation of mixed solvent electrolytes for ambient temperature secondary lithium cells

The ethylene carbonate/2-methyltetrahydrofuran (EC/2-MeTHF) mixed-solvent electrolyte has been experimentally found to possess many desirable electrolyte characteristics for ambient-temperature secondary Li-TiS2 cell applications. As many as 300 cycles have been demonstrated, and a cycling efficiency figure-of-merit of 38.5 percent, for 10-percent EC/90-percent MeTHF mixed-solvent electrolyte in experimental Li-TiS2 cells. The improved performance of this electrolyte is attributable to the formation of a beneficial passivating film on the Li electrode by interaction with the EC.

Shen, D. H.↗