CA2069181C - Electrochemical cell that delivers high power pulses - Google Patents
Electrochemical cell that delivers high power pulsesInfo
- Publication number
- CA2069181C CA2069181C CA002069181A CA2069181A CA2069181C CA 2069181 C CA2069181 C CA 2069181C CA 002069181 A CA002069181 A CA 002069181A CA 2069181 A CA2069181 A CA 2069181A CA 2069181 C CA2069181 C CA 2069181C
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- CA
- Canada
- Prior art keywords
- electrolyte
- pmt
- electrochemical cell
- lialcl
- alcl
- Prior art date
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0561—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
- H01M10/0563—Liquid materials, e.g. for Li-SOCl2 cells
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/60—Selection of substances as active materials, active masses, active liquids of organic compounds
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Battery Electrode And Active Subsutance (AREA)
- Secondary Cells (AREA)
- Primary Cells (AREA)
Abstract
An electrochemical cell is provided that delivers high power pulses, the cell including poly 3-methylthiophene as the cathode, a member of the group consisting of Li(SO ) AlCl , 1.0 M LiAlCl -SOCl and 1.0 M LiAlCl -SO Cl as the electrolyte, and lith-ium as the anode.
Description
FIELD OF INv~N~l~ION
This invention relates in general to an electrochemical cell that delivers high power pulses and in particular to such a cell that includes poly 3-methylthiophene, PMT as the cathode, a member of the group consisting of Li(SO ) AlC1 , 1.0 M LiAlC1 -SOCl , and
This invention relates in general to an electrochemical cell that delivers high power pulses and in particular to such a cell that includes poly 3-methylthiophene, PMT as the cathode, a member of the group consisting of Li(SO ) AlC1 , 1.0 M LiAlC1 -SOCl , and
2 3 4 4 2 1.0 M LiAlCl -SO Cl as the electrolyte, and lithium as the anode.
R~CR~ROUND OF THE lNv~N-llON
There has been interest in high voltage lithium electro-chemical cells for pulse power reserve cells as well as for pulseapplications. Heretofore, this need has been met by the use of porous carbon cathodes. This has not been entirely satisfactory because pulse power is derived predo~;n~ntly at the electrode sur-face rather than from the interior bulk. Thus, thin polymer elec-trodes would be more efficient than the porous carbon cathodes since there is more surface area and less wasted interior space per unit volume in the case of the thin polymer electrodes.
SUMMARY OF THE lNv~NlION
The general object of this invention is to provide an elec-trochemical cell capable of delivering high power pulses. A morespecific object, of the invention is to provide a lithium electrochem-ical cell able to deliver high power pulses over seconds or minutes with volumetric power density exceeding porous carbon cathode tech-nology.
It has now been found that the aforementioned objects can be attained by providing an electrochemical cell including PMT as 206918 ~
the cathode, a member of the group consisting of Li(SO ) AlCl , 1.0 M LiAlCl -SOCl and 1.0 M LiAlCl -SO Cl as the electrolyte, and lithium as the anode.
Thin films of PMT can be easily polymerized electrochemical-ly, controlling film thickness by the number of coulombs of charge passed. When reduced (undoped), PMT is electrically insulating, but in the doped state, has an electrical conductivity in the range of 10-2000 S cm depending on the method of preparation and dopant anion. Controlling polymerization electrochemically allows fabrica-tion of conductive films that are much thinner than cathodes pre-pared, for example, with Teflon-bonded porous carbon. The polymer films can be pulse discharged in Li(SO ) AlCl , 1 LiAlCl -SOCl and 1.0 M LiAlCl -SO Cl electrolytes to yield very high volumetric power densities. Power levels per cm of polymer ca~hode are substan-tially higher than for Teflon bonded porous carbon cathodes.
Thus, according to the invention, thin, electrically con-ducting PMT films are formed electrochemically and used as cathodes in electrochemical cells. The pulse power capabilities of 1.4 ~m thick PMT films discharged in Li(SO ) AlCl , 1.0 M LiAlCl -SO Cl 2 3 4 4 2 2 0 and 1.0 M LiAlCl -SOCl are determined. A volumetric power density (for PMT) of 600 W cm is sustained for 30 seconds at an operating potential of about 3.0V in both thionyl chloride (SOCl ) and sulfuryl chloride (SO Cl ). A power density of 429 W
_3 2 2 cm is sustained for 2 minutes (operating at approximately 3.0 V) when PMT is discharged in SOCl . Power densities are less in the sulfur dioxide based electrolyte, but the PMT cathode is able to be discharged and recharged for mahy cycles. Multiple 4 second pulses in the SO electrolyte averaging about 300 W cm are reproducible over many cycles.
trade-mark [polytetrafluoroethylene (PTFE)l 2~6g~8~
According to the invention, polymer cathode is obtainable that is electrically conductive and able to be tailored to any de-sired thickness by the amount of charge passed during electropoly~
merization. Thicknesses on the order of one micron are easily fabricated, whereas Teflon-bonded porous carbon cathodes are necessarily much thicker.
Moreover, one can discharge PMT at high power levels (and high operating voltage) in inorganic electrolytes containing SO , SOCl , and SO Cl .
Then too, power densities are obtainable that are much higher than for (thicker) porous carbon cathodes. Power densities of 600 W cm can be sustained for at least 30 seconds at a 3.0 V
operating potential.
In Li(SO ) AlCl electrolyte, multiple four second constant current pulses can be performed at a power density of approximately 500 W cm . The cell is then able to be recharged and reproducibly pulse discharged for many cycles.
Even higher power can probably be obtained by preparing PMT
by another method to increase surface area, or through the use of other high surface area polymers. Given the ease with which thin, electrochemically-formed films can be prepared, it should be possible to construct bipolar cells capable of delivering high power pulses.
Polymerization of PMT can be carried out in a 125 ml European flask (Ace Glass) using a 1 cm platinum flag counter elec-trode, a SSCE reference electrode, and a platinum or glassy carbon rod working electrode. Glassy carbon and platinum rods (0.071 cm cross section) are polished to a mirror finish with a 0.1 micron * trade-mark [polytetrafluoroethylene (PTFE)]
X~9181 alumina/water paste. The rod is sheat}led in heat shrinkable Teflon*
so as to expose only the cros~ sectional area at the end of the rod.
The cell is flooded with electrolyte containing 0.1 M 3-methylthio-phene monomer (Sigma Chemical, 99+%) and 0.1 M tetrabutylammonium tetrafluoroborate (Alpha), with redistilled acetonitrile (Fisher) as the solvent. Ultra high purity dry argon is bubbled through the electrolyte to remove oxygen.
Adherent films, 1.4Jum thick (measured by SEM), are fabri-cated at 10 mA cm by a pulse deposition process, where 0.25 C
cm is passed in five cycles with ~ive minute rest periods (at open circuit) between cycles. The PMT-coated rod is then rinsed in acetonitrile and dried under vacuum at 50 C. To a first approxi-mation (assuming 100% plating efficiency), a maximum of 4.52 X 10 g of 3-methylthiophene is deposited on the substrate. Based on the cross-sectional area and thickness, the volume of the film i8 9.9S x 10 cm .
Li(SO ) AlCl electrolyte is prepared with anhydrous LiAlCl (Anderson Physics) and excess dry liquid SO (Matheson) by combining them in an evacuated Teflon*cell (able to withstalld pressure). After dissolution of the salt, excess SO is slowly bled off through a bubbler containing halocarbon oil. The resultant electrolyte is between 3 and 3.5 SO molecules per LiAlCl molec-ule as measured by weight. Anhydrous LiC1 is added to scavenge any excess AlCl and ensure a neutral electrolyte. Electrolytes con-taining sulfuryl chloride and thionyl chloride are prepared by dis-solving LiAlCl (Anderson Physics) to form a 1.0 molar solution, then adding anhydrous LiCl to ensure solution neutrality.
* trade-mark [polytetrafluoroethylene (PTFE) ~
~ ~t ~ 4-Upon polymeriztion in the acetonitrile-based electrolyte, PMT is doped with BF anions. Constant current discharge capac-ity in Li(S0 ) AlCl electrolyte is improved when BF dop-ant ions are replaced with AlCl from the electrolyte. There-fore, all experiments with Li(SO ) AlCl electrolyte are performed_ 2 3 4 with AlCl -doped PMT. The usual method of treatment is to undope BF from the polymer in LiAlCl -3SO electrolyte by holding the potential at 3.0 V (vs lithium) and then doping AlCl by charging at a constant potential of 3.8 V. Mini~-l electrolyte reduction would occur while undoping the polymer at 3.0 V since reduction of electro-lyte occurs below this potential. After doping with AlCl and then standing overnight, the cell potential equilibrates at 3.4 V. At
R~CR~ROUND OF THE lNv~N-llON
There has been interest in high voltage lithium electro-chemical cells for pulse power reserve cells as well as for pulseapplications. Heretofore, this need has been met by the use of porous carbon cathodes. This has not been entirely satisfactory because pulse power is derived predo~;n~ntly at the electrode sur-face rather than from the interior bulk. Thus, thin polymer elec-trodes would be more efficient than the porous carbon cathodes since there is more surface area and less wasted interior space per unit volume in the case of the thin polymer electrodes.
SUMMARY OF THE lNv~NlION
The general object of this invention is to provide an elec-trochemical cell capable of delivering high power pulses. A morespecific object, of the invention is to provide a lithium electrochem-ical cell able to deliver high power pulses over seconds or minutes with volumetric power density exceeding porous carbon cathode tech-nology.
It has now been found that the aforementioned objects can be attained by providing an electrochemical cell including PMT as 206918 ~
the cathode, a member of the group consisting of Li(SO ) AlCl , 1.0 M LiAlCl -SOCl and 1.0 M LiAlCl -SO Cl as the electrolyte, and lithium as the anode.
Thin films of PMT can be easily polymerized electrochemical-ly, controlling film thickness by the number of coulombs of charge passed. When reduced (undoped), PMT is electrically insulating, but in the doped state, has an electrical conductivity in the range of 10-2000 S cm depending on the method of preparation and dopant anion. Controlling polymerization electrochemically allows fabrica-tion of conductive films that are much thinner than cathodes pre-pared, for example, with Teflon-bonded porous carbon. The polymer films can be pulse discharged in Li(SO ) AlCl , 1 LiAlCl -SOCl and 1.0 M LiAlCl -SO Cl electrolytes to yield very high volumetric power densities. Power levels per cm of polymer ca~hode are substan-tially higher than for Teflon bonded porous carbon cathodes.
Thus, according to the invention, thin, electrically con-ducting PMT films are formed electrochemically and used as cathodes in electrochemical cells. The pulse power capabilities of 1.4 ~m thick PMT films discharged in Li(SO ) AlCl , 1.0 M LiAlCl -SO Cl 2 3 4 4 2 2 0 and 1.0 M LiAlCl -SOCl are determined. A volumetric power density (for PMT) of 600 W cm is sustained for 30 seconds at an operating potential of about 3.0V in both thionyl chloride (SOCl ) and sulfuryl chloride (SO Cl ). A power density of 429 W
_3 2 2 cm is sustained for 2 minutes (operating at approximately 3.0 V) when PMT is discharged in SOCl . Power densities are less in the sulfur dioxide based electrolyte, but the PMT cathode is able to be discharged and recharged for mahy cycles. Multiple 4 second pulses in the SO electrolyte averaging about 300 W cm are reproducible over many cycles.
trade-mark [polytetrafluoroethylene (PTFE)l 2~6g~8~
According to the invention, polymer cathode is obtainable that is electrically conductive and able to be tailored to any de-sired thickness by the amount of charge passed during electropoly~
merization. Thicknesses on the order of one micron are easily fabricated, whereas Teflon-bonded porous carbon cathodes are necessarily much thicker.
Moreover, one can discharge PMT at high power levels (and high operating voltage) in inorganic electrolytes containing SO , SOCl , and SO Cl .
Then too, power densities are obtainable that are much higher than for (thicker) porous carbon cathodes. Power densities of 600 W cm can be sustained for at least 30 seconds at a 3.0 V
operating potential.
In Li(SO ) AlCl electrolyte, multiple four second constant current pulses can be performed at a power density of approximately 500 W cm . The cell is then able to be recharged and reproducibly pulse discharged for many cycles.
Even higher power can probably be obtained by preparing PMT
by another method to increase surface area, or through the use of other high surface area polymers. Given the ease with which thin, electrochemically-formed films can be prepared, it should be possible to construct bipolar cells capable of delivering high power pulses.
Polymerization of PMT can be carried out in a 125 ml European flask (Ace Glass) using a 1 cm platinum flag counter elec-trode, a SSCE reference electrode, and a platinum or glassy carbon rod working electrode. Glassy carbon and platinum rods (0.071 cm cross section) are polished to a mirror finish with a 0.1 micron * trade-mark [polytetrafluoroethylene (PTFE)]
X~9181 alumina/water paste. The rod is sheat}led in heat shrinkable Teflon*
so as to expose only the cros~ sectional area at the end of the rod.
The cell is flooded with electrolyte containing 0.1 M 3-methylthio-phene monomer (Sigma Chemical, 99+%) and 0.1 M tetrabutylammonium tetrafluoroborate (Alpha), with redistilled acetonitrile (Fisher) as the solvent. Ultra high purity dry argon is bubbled through the electrolyte to remove oxygen.
Adherent films, 1.4Jum thick (measured by SEM), are fabri-cated at 10 mA cm by a pulse deposition process, where 0.25 C
cm is passed in five cycles with ~ive minute rest periods (at open circuit) between cycles. The PMT-coated rod is then rinsed in acetonitrile and dried under vacuum at 50 C. To a first approxi-mation (assuming 100% plating efficiency), a maximum of 4.52 X 10 g of 3-methylthiophene is deposited on the substrate. Based on the cross-sectional area and thickness, the volume of the film i8 9.9S x 10 cm .
Li(SO ) AlCl electrolyte is prepared with anhydrous LiAlCl (Anderson Physics) and excess dry liquid SO (Matheson) by combining them in an evacuated Teflon*cell (able to withstalld pressure). After dissolution of the salt, excess SO is slowly bled off through a bubbler containing halocarbon oil. The resultant electrolyte is between 3 and 3.5 SO molecules per LiAlCl molec-ule as measured by weight. Anhydrous LiC1 is added to scavenge any excess AlCl and ensure a neutral electrolyte. Electrolytes con-taining sulfuryl chloride and thionyl chloride are prepared by dis-solving LiAlCl (Anderson Physics) to form a 1.0 molar solution, then adding anhydrous LiCl to ensure solution neutrality.
* trade-mark [polytetrafluoroethylene (PTFE) ~
~ ~t ~ 4-Upon polymeriztion in the acetonitrile-based electrolyte, PMT is doped with BF anions. Constant current discharge capac-ity in Li(S0 ) AlCl electrolyte is improved when BF dop-ant ions are replaced with AlCl from the electrolyte. There-fore, all experiments with Li(SO ) AlCl electrolyte are performed_ 2 3 4 with AlCl -doped PMT. The usual method of treatment is to undope BF from the polymer in LiAlCl -3SO electrolyte by holding the potential at 3.0 V (vs lithium) and then doping AlCl by charging at a constant potential of 3.8 V. Mini~-l electrolyte reduction would occur while undoping the polymer at 3.0 V since reduction of electro-lyte occurs below this potential. After doping with AlCl and then standing overnight, the cell potential equilibrates at 3.4 V. At
3.0 V, reduction of SOCl and SO Cl occurs, so polymer undoping iB not possible in these electrolytes. Holding the potential at 3.8 V to force AlCl doping in SOCl electrolyte is not benefi-
4 2 cial on subsequent discharge. Therefore, discharges in SOCl and SO Cl electrolytes are performed with BF -doped polymer.
OCV in these electrolytes is 3.53 and 3.83 V respectively.
To control experiments, a PAR Model 173 potentiostat/
galvanostat with a model 276 plug-in interface is used in conjunction with a Hewlett Packard HP-86 computer. The experimental cell for the pulse experiments is a 125 ml European flask flooded with 20 ml of Li(SO ) AlCl electrolyte, containing a large lithium counter electrode and lithium reference.
DESCRIPTION OF THE TABLE, DRAWING
AND PREFERRED EMBODIMENT
Table 1 shows comparison of current density and power density for 1.4 ~m thick PMT and 1090 ~m thick PTFE-bonded porous carbon (75% Shawinigan, 25% Ketjen black) cathodes. Li/Li(SO ) AlCl /cathode cell stepped from OCV to 2.6 V.
Figure 1 shows voltage and power density as a function of discharge time at 10 mA cm constant current, for a 1.4 ~m thick PMT cathode and lithium anode in either 1.0 M LiAlCl -SOCl , 1.0 M LiAlC1 -SO Cl , or Li(SO ) AlC1 electrolyte.
Figure 2 shows voltage and power density as a function of discharge time at 20 mA cm constant current, for a 1.4Jum thick PMT cathode and lithium anode in either 1.0 M LiAlCl -SOCl , 1.0 M LiAlCl -SO Cl , or Li(SO ) AlCl electrolyte.
Figure 3 shows voltage and power density as a function of discharge time at 30 mA cm constant current, for a 1.4 um thick PMT cathode and lithium anode in either 1.0 M LiAlCl -SOCl , or 1.0 M LiAlCl -SO Cl electrolyte.
Figure 4 shows power and current density for up to 5 s following a potential step from open circuit to 2.6 V. Li/Li(SO ) AlCl cell with 1.4 um thick PMT (circle) and 1090 um thick PTFE-bonded 75% Sawinigan-25% Retjen black cathode (square).
Figure 5 shows final potential of Li/Li(SO ) AlCl /1.4 um PMT cell after each 4 second, 15 mA cm pulse with 1 s open cir-cuit rest periods. Recharge is at 0.2 mA cm to a 3.8 V cutoff.
First (square) and 21st (circle) pulse sets are shown.
Figure 6 shows final potential of Li/Li(SO ) AlCl /1.4 um PMT cell after each 4 second, 25 mA cm pulse with 1 s open cir-cuit rest periods. Recharge is at 0.2 mA cm to a 3.8 V cutoff.
Second (square) and 35th (circle) pulse sets are shown.
Constant current discharge of PMT is carried out at 10, 20 and 30 mA cm . Cell potential and volumetric power density are shown in Figures 1-3. Lowest operating potential and shortest discharge times are observed in the sulfur dioxide based electrolyte. Although the sulfuryl chloride electrolyte initially provides the highest operating potential, the thionyl chloride based electrolyte has the longest cell capacity at all current densities. At 30 mA cm , PMT
can deliver about 600 W cm at a potential of 3.0 V in both sul-furyl chloride and thionyl chloride for at least 0.5 minutes. To a 2.0 V cutoff, PMT can be discharged for 1.25 minutes at power dens-ities above 400 W cm . At a lower current density of 20 mA cm PMT in thionyl chloride can be discharged for nearly 2 minutes at a 3.0 V operating potential and 429 W cm power density. By comp-arison, discharge in sulfur dioxide is poor. However, PMT is able to be cycled (discharged and charged) in the SO -based electrolyte.
2C In Figure 4, pulse power (potential step to 2.6 V) is shown for up to five seconds, whereafter 1.4 ~m thick PMT delivers about 0.07 W cm (26 mA cm ; 489 W cm ). Comparison is made to a 1090 ~m thick conventional PTFE-bonded porous carbon electrode, with a 75:25 mixture of Shawinigan acetylene black and Ketjen black.
The area and volume of this electrode are 0.5 cm (counting both sides of a 0.25 cm cathode) and 0.027 cm respectively. The polymer film provides a vast improvement in power density compared - 20~9181 to the established Teflon*bonded porous carbon technology. The thick porous carbon electrode sustains a high current density ~135 mA cm ) after 5 s; however, PMT delivers more power per cm for nearly one second. On a volumetric basis, after 5 seconds, the power densities for PMT and poro`us carbon are ~89 W cm and 6.5 W
cm respectively (Table 1). For short term pulses, PMT is superi-or to thicker porous carbon electrodes, and can be more easily fabricated as a bipolar stack of very thin electrodes.
The superior pulse power of PMT (compared to porous car-bons) is not a result of polymer surface area (4.13 m g- , measured by a one point BET surface area analysis) since carbon blacks have much greater surface areas (60-1500 m g ).
Finally, PMT i8 also evaluated for intermittent constant current pulse power in Li (SO ) AlC1 electrolyte. A
constant current load is applied for four seconds, and cell potential measured at the end of this period. Following a one second rest at open circuit, the cell is pulsed again, repeating this procedure until cell potential falls below 2.0 V. Then the cell is recharged at 0.2 mA cm to a 3.8 V cutoff, after which the next cycle is begun. The potential at the end of each four ~econd pulse i8 shown in Figures 5 and 6. In Flgure 5, PMT is pulse discharged at 15 mA cm . In the first set of pulse discharges, eight pulses are obtained. After 20 cycles, the 21st set also provides eight pulses. Except for the last pulse, final potentials are remarkably similar even after 21 cycles. Final potentials during the first six pulses ranges between 3.0 on the * trade-mark lpolytetrafluoroethylene (PTFE)]
20~18l first pulse to 2.7 V on the sixth pulse, corresponding to power densities of 321 and 289 W cm respectively. Figure 6 shows data at a 25 mA cm rate. Here, four or five pulses are obtained for 35 cycles. The first three pulses are very reproducible, with final potentials between 2.9 and 2.6 V and power densities of 518 to 464 W cm respectively. These experiments demonstrate the ability of PMT to deliver several high power pulses over a short time period, reproducibly repeated for several cycles in Li(SO ) AlCl electrolyte.
I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described for obvious modifications will occur to a person skilled in the art.
_g _
OCV in these electrolytes is 3.53 and 3.83 V respectively.
To control experiments, a PAR Model 173 potentiostat/
galvanostat with a model 276 plug-in interface is used in conjunction with a Hewlett Packard HP-86 computer. The experimental cell for the pulse experiments is a 125 ml European flask flooded with 20 ml of Li(SO ) AlCl electrolyte, containing a large lithium counter electrode and lithium reference.
DESCRIPTION OF THE TABLE, DRAWING
AND PREFERRED EMBODIMENT
Table 1 shows comparison of current density and power density for 1.4 ~m thick PMT and 1090 ~m thick PTFE-bonded porous carbon (75% Shawinigan, 25% Ketjen black) cathodes. Li/Li(SO ) AlCl /cathode cell stepped from OCV to 2.6 V.
Figure 1 shows voltage and power density as a function of discharge time at 10 mA cm constant current, for a 1.4 ~m thick PMT cathode and lithium anode in either 1.0 M LiAlCl -SOCl , 1.0 M LiAlC1 -SO Cl , or Li(SO ) AlC1 electrolyte.
Figure 2 shows voltage and power density as a function of discharge time at 20 mA cm constant current, for a 1.4Jum thick PMT cathode and lithium anode in either 1.0 M LiAlCl -SOCl , 1.0 M LiAlCl -SO Cl , or Li(SO ) AlCl electrolyte.
Figure 3 shows voltage and power density as a function of discharge time at 30 mA cm constant current, for a 1.4 um thick PMT cathode and lithium anode in either 1.0 M LiAlCl -SOCl , or 1.0 M LiAlCl -SO Cl electrolyte.
Figure 4 shows power and current density for up to 5 s following a potential step from open circuit to 2.6 V. Li/Li(SO ) AlCl cell with 1.4 um thick PMT (circle) and 1090 um thick PTFE-bonded 75% Sawinigan-25% Retjen black cathode (square).
Figure 5 shows final potential of Li/Li(SO ) AlCl /1.4 um PMT cell after each 4 second, 15 mA cm pulse with 1 s open cir-cuit rest periods. Recharge is at 0.2 mA cm to a 3.8 V cutoff.
First (square) and 21st (circle) pulse sets are shown.
Figure 6 shows final potential of Li/Li(SO ) AlCl /1.4 um PMT cell after each 4 second, 25 mA cm pulse with 1 s open cir-cuit rest periods. Recharge is at 0.2 mA cm to a 3.8 V cutoff.
Second (square) and 35th (circle) pulse sets are shown.
Constant current discharge of PMT is carried out at 10, 20 and 30 mA cm . Cell potential and volumetric power density are shown in Figures 1-3. Lowest operating potential and shortest discharge times are observed in the sulfur dioxide based electrolyte. Although the sulfuryl chloride electrolyte initially provides the highest operating potential, the thionyl chloride based electrolyte has the longest cell capacity at all current densities. At 30 mA cm , PMT
can deliver about 600 W cm at a potential of 3.0 V in both sul-furyl chloride and thionyl chloride for at least 0.5 minutes. To a 2.0 V cutoff, PMT can be discharged for 1.25 minutes at power dens-ities above 400 W cm . At a lower current density of 20 mA cm PMT in thionyl chloride can be discharged for nearly 2 minutes at a 3.0 V operating potential and 429 W cm power density. By comp-arison, discharge in sulfur dioxide is poor. However, PMT is able to be cycled (discharged and charged) in the SO -based electrolyte.
2C In Figure 4, pulse power (potential step to 2.6 V) is shown for up to five seconds, whereafter 1.4 ~m thick PMT delivers about 0.07 W cm (26 mA cm ; 489 W cm ). Comparison is made to a 1090 ~m thick conventional PTFE-bonded porous carbon electrode, with a 75:25 mixture of Shawinigan acetylene black and Ketjen black.
The area and volume of this electrode are 0.5 cm (counting both sides of a 0.25 cm cathode) and 0.027 cm respectively. The polymer film provides a vast improvement in power density compared - 20~9181 to the established Teflon*bonded porous carbon technology. The thick porous carbon electrode sustains a high current density ~135 mA cm ) after 5 s; however, PMT delivers more power per cm for nearly one second. On a volumetric basis, after 5 seconds, the power densities for PMT and poro`us carbon are ~89 W cm and 6.5 W
cm respectively (Table 1). For short term pulses, PMT is superi-or to thicker porous carbon electrodes, and can be more easily fabricated as a bipolar stack of very thin electrodes.
The superior pulse power of PMT (compared to porous car-bons) is not a result of polymer surface area (4.13 m g- , measured by a one point BET surface area analysis) since carbon blacks have much greater surface areas (60-1500 m g ).
Finally, PMT i8 also evaluated for intermittent constant current pulse power in Li (SO ) AlC1 electrolyte. A
constant current load is applied for four seconds, and cell potential measured at the end of this period. Following a one second rest at open circuit, the cell is pulsed again, repeating this procedure until cell potential falls below 2.0 V. Then the cell is recharged at 0.2 mA cm to a 3.8 V cutoff, after which the next cycle is begun. The potential at the end of each four ~econd pulse i8 shown in Figures 5 and 6. In Flgure 5, PMT is pulse discharged at 15 mA cm . In the first set of pulse discharges, eight pulses are obtained. After 20 cycles, the 21st set also provides eight pulses. Except for the last pulse, final potentials are remarkably similar even after 21 cycles. Final potentials during the first six pulses ranges between 3.0 on the * trade-mark lpolytetrafluoroethylene (PTFE)]
20~18l first pulse to 2.7 V on the sixth pulse, corresponding to power densities of 321 and 289 W cm respectively. Figure 6 shows data at a 25 mA cm rate. Here, four or five pulses are obtained for 35 cycles. The first three pulses are very reproducible, with final potentials between 2.9 and 2.6 V and power densities of 518 to 464 W cm respectively. These experiments demonstrate the ability of PMT to deliver several high power pulses over a short time period, reproducibly repeated for several cycles in Li(SO ) AlCl electrolyte.
I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described for obvious modifications will occur to a person skilled in the art.
_g _
Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An electrochemical cell capable of delivering high power pulses, said electrochemical cell including poly 3-methylthiophene as the cathode, a member of the group consisting of Li(SO ) AlCl , 1.0 M LiAlCl -SOCl and 1.0 M LiAlCI
SO Cl as the electrolyte and lithium as the anode.
SO Cl as the electrolyte and lithium as the anode.
2. An electrochemical cell according to claim 1 wherein the electrolyte is Li(SO ) AlCl .
3. An electrochemical cell according to claim 1 wherein the electrolyte is 1.0 M LiAlCl -SOCl .
4. An electrochemical cell according to claim 1 wherein the electrolyte is 1.0 M LiAlCl -SO Cl .
5. An electrochemical cell according to claim 1 wherein the cell is rechargeable.
6. An electrochemical cell according to claim 1 wherein the poly 3-methylthiophene cathode is electrochemically formed as a thin, electrically conducting film.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/715,265 USH1054H (en) | 1991-06-14 | 1991-06-14 | Electrochemical cell that delivers high power pulses |
| US07/715,265 | 1991-06-14 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2069181A1 CA2069181A1 (en) | 1992-12-15 |
| CA2069181C true CA2069181C (en) | 1997-04-01 |
Family
ID=24873308
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002069181A Expired - Fee Related CA2069181C (en) | 1991-06-14 | 1992-05-21 | Electrochemical cell that delivers high power pulses |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | USH1054H (en) |
| CA (1) | CA2069181C (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BR112015018315B1 (en) * | 2013-02-07 | 2021-07-06 | Innolith Assets Ag | electrolyte, for an electrochemical battery cell, containing sulfur dioxide and a conductive salt; electrochemical battery cell; and process for producing an electrolyte for an electrochemical battery cell |
| JPWO2020175171A1 (en) * | 2019-02-28 | 2021-12-23 | パナソニックＩｐマネジメント株式会社 | Electrolyte material and batteries using it |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2527844B1 (en) | 1982-06-01 | 1986-01-24 | Thomson Csf | ELECTROCHROMIC DEVICE THAT CAN BE USED FOR ENERGY STORAGE AND ELECTROCHROMIC DISPLAY SYSTEM |
| US4472488A (en) | 1983-11-30 | 1984-09-18 | Allied Corporation | Polymeric electrode coated with reaction product of cyclic compound |
| US4556617A (en) | 1984-06-26 | 1985-12-03 | Raychem Corporation | Anhydrous primary battery |
| FR2574223B1 (en) | 1984-12-03 | 1987-05-07 | Accumulateurs Fixes | ELECTROCHEMICAL GENERATOR OF WHICH THE NEGATIVE ACTIVE MATERIAL IS BASED ON AN ALKALINE OR ALKALINOTERROUS METAL |
| DE3506659A1 (en) | 1985-02-26 | 1986-08-28 | Basf Ag, 6700 Ludwigshafen | COMPOSITE ELECTRODE |
| DE3607378A1 (en) | 1986-03-06 | 1987-09-10 | Basf Ag | ELECTROCHEMICAL SECONDARY ELEMENT WITH AT LEAST ONE POLYMER ELECTRODE |
| CA1297941C (en) | 1987-03-13 | 1992-03-24 | Yukio Kobayashi | Nonaqueous secondary battery |
| DE3843412A1 (en) | 1988-04-22 | 1990-06-28 | Bayer Ag | NEW POLYTHIOPHENES, METHOD FOR THEIR PRODUCTION AND THEIR USE |
| US4957833A (en) | 1988-12-23 | 1990-09-18 | Bridgestone Corporation | Non-aqueous liquid electrolyte cell |
-
1991
- 1991-06-14 US US07/715,265 patent/USH1054H/en not_active Abandoned
-
1992
- 1992-05-21 CA CA002069181A patent/CA2069181C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| USH1054H (en) | 1992-05-05 |
| CA2069181A1 (en) | 1992-12-15 |
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| Date | Code | Title | Description |
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| EEER | Examination request | ||
| MKLA | Lapsed |