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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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17 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2019

Metallized Plastic Current Collectors

Metallized plastic current collectors are an innovation patented by the Soteria Battery Innovation Group with the promise of isolating active material involved in an internal short by vaporizing and isolating the short from the rest of the cell electrode jellyroll or stack. Partnering with NREL, UCL, Coulometrics, and Soteria, NASA is leading a research effort into demonstrating the merits and understanding the phenomena of this safety innovation using prototype 18650 cylindrical cells vs control cells with standard metal foil current collectors. Cells with and without the plastic collector, with and without the on-demand internal short circuit device, and with polymer or cellulose separators were made. Safety evaluations were done with driving cells into thermal runaway (TR) with thermal and nail penetration triggers while inside our TR calorimeter and with ultra high speed X-ray videography provided at Synchrotrons. Preliminary results suggests that the thermally unstable plastic current collector innovation has great promise for preventing TR or reducing the severity of the TR output.

Li-ion cell↗
NASA NTRSDate not supplied

Investigating the Ability of Plastic Current Collectors to Isolate Internal Shorts

Metallized plastic current collectors in Li-ion cells reduce mass and reduce the internal short circuit hazard compared to aluminum and copper foils. Shorts induced by nail and by our internal short circuit device were performed on control 18650 cells and on cells with the collectors replaced with metallized polyester and aramid films. Tests were performed inside our fractional thermal runaway calorimeter to quantify the heat transferred and its distributions and those runs done at a synchrotron yielded fascinating very high speedX-ray videography. These show tolerance to nail penetration and activation of defect internal shorts and when thermally forced into thermal runaway, the heat output is significantly reduced. Very high resolutionCT scans, cross sections, and cell tear downs give insights into the thermal and mechanism for these plastic collectors.

Plastic Current Collectors↗
DOE OSTI2025

High tensile alloy of copper to mitigate current collector deformation in silicon electrodes for lithium-ion batteries

The volumetric changes of silicon electrodes, along with the strong adhesive properties of certain binders, can lead to plastic deformation of the current collector and create damage in the electrode coating. Here, in this study, we report a detailed study of silicon coatings on a high-tensile alloy (HTA) foil of copper with strength over twice that of conventional copper foils. The HTA current collectors with high mechanical strength can mitigate plastic deformation upon continuous cycling. At moderate areal capacities (2.5–3 mAh cm −2 ), conventional copper foils show significant wrinkling after only a few electrochemical cycles, whereas the HTA foils remain intact. We demonstrate viability of the HTA foils in large format xx6395 pouch cells, in which the HTA current collectors remain intact even at an areal capacity of 4.5 mAh cm −2 ; in contrast, wrinkles form in conventional copper current collectors increasing the likelihood of lithium plating. Computational studies show that stresses generated during cycling of silicon electrodes are very high in the current collector and at the current collector-coating interface, explaining the wrinkling of conventional Cu foils. Our studies highlight importance of current collector to solve the electrochemical and chemo-mechanical performance challenges associated with high-loading silicon electrodes.

Chemo-mechanical degradation↗
NASA NTRS1999

Bipolar Nickel-Metal Hydride Battery Development Project

This paper reviews the development of the Electro Energy, Inc.'s bipolar nickel metal hydride battery. The advantages of the design are that each cell is individually sealed, and that there are no external cell terminals, no electrode current collectors, it is compatible with plastic bonded electrodes, adaptable to heat transfer fins, scalable to large area, capacity and high voltage. The design will allow for automated flexible manufacturing, improved energy and power density and lower cost. The development and testing of the battery's component are described. Graphic presentation of the results of many of the tests are included.

Cole, John H.↗
NASA NTRS1998

Development of a Woven-Grid Quasi-Bipolar Battery

This report describes an analytical and experimental investigation of AeroVironment's Quasi-Bipolar battery concept. The modelling/battery design part of the study demonstrates that there is a trade-off between thermal and specified electrical performance. Even so, quasi-bipolar batteries can be designed, with ten times better thermal uniformity, that meet or exceed current state-of-the-art hybrid-electric vehicle battery pack performance, even using the same active materials. The thermal uniformity, power, and energy for these quasi-bipolar battery packs is projected to be very good. The experimental part of the investigation demonstrates the concept of the quasi-bipolar plate applied to a lead foil current collector wrapping around two sides of an inexpensive plastic film core. Approximately 50 quasi-biplate samples were fabricated using a hot laminating press. Hot lamination with "texture" between the plastic and lead shows some promise as a low cost method for fabricating the plates. Five of these plates were assembled into two cells plus one two-cell battery. Data from these test cells were compared with existing data for similar true bipolar batteries. The positive side of the plates exhibited corrosion where not protected by the active material.

Tokumaru, P.↗
NASA NTRS1994

Bipolar Ag-Zn battery

The silver-zinc (AgZn) battery system has been unique in its ability to safely satisfy high power demand applications with low mass and volume. However, a new generation of defense, aerospace, and commercial applications will impose even higher power demands. These new power demands can be satisfied by the development of a bipolar battery design. In this configuration the power consuming, interelectrode current conductors are eliminated while the current is then conducted via the large cross-section electrode substrate. Negative and positive active materials are applied to opposite sides of a solid silver foil substrate. In addition to reducing the weight and volume required for a specified power level, the output voltage performance is also improved as follows. Reduced weight through: elimination of the plastic cell container; elimination of plate leads and intercell connector; and elimination of internal plate current collector. Increased voltage through: elimination of resistance of current collector; elimination of resistance of plate lead; and elimination of resistance of intercell connector. EPI worked previously on development of a secondary bipolar silver zinc battery. This development demonstrated the electrical capability of the system and manufacturing techniques. One difficulty with this development was mechanical problems with the seals. However, recent improvements in plastics and adhesives should eliminate the major problem of maintaining a seal around the periphery of the bipolar module. The seal problem is not as significant for a primary battery application or for a requirement for only a few discharge cycles. A second difficulty encountered was with activation (introducing electrolyte into the cell) and with venting gas from the cell without loss of electrolyte. During previous work, the following projections for energy density were made from test data for a high power system which demonstrated in excess of 50 discharge/charge cycles. Projected system power = 100 kilowatts; discharge time = 30 seconds; discharge current density = 1.75 amps/sq in.; system weight = 86 lbs (9.7 WH/lb); and system volume = 1071 cu. in. (.78 WH/cu. in.). EPI is currently working on a development program to produce a bipolar silver-zinc battery design for NASA. The potential application would be to power electromechanical actuators for space launch vehicles.

Giltner, L. John↗