Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
  • H01M50/202—Casings or frames around the primary casing of a single cell or a single battery
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  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/04—Construction or manufacture in general
  • H01M10/0413—Large-sized flat cells or batteries for motive or stationary systems with plate-like electrodes
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  • H01M10/00—Secondary cells; Manufacture thereof
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  • H01M10/0468—Compression means for stacks of electrodes and separators
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  • H01M12/00—Hybrid cells; Manufacture thereof
  • H01M12/04—Hybrid cells; Manufacture thereof composed of a half-cell of the fuel-cell type and of a half-cell of the primary-cell type
  • H01M12/06—Hybrid cells; Manufacture thereof composed of a half-cell of the fuel-cell type and of a half-cell of the primary-cell type with one metallic and one gaseous electrode
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  • H01M12/06—Hybrid cells; Manufacture thereof composed of a half-cell of the fuel-cell type and of a half-cell of the primary-cell type with one metallic and one gaseous electrode
  • H01M12/065—Hybrid cells; Manufacture thereof composed of a half-cell of the fuel-cell type and of a half-cell of the primary-cell type with one metallic and one gaseous electrode with plate-like electrodes or stacks of plate-like electrodes
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  • H01M4/02—Electrodes composed of, or comprising, active material
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  • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
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  • H01M4/64—Carriers or collectors
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  • H01M4/8605—Porous electrodes
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  • H01M4/96—Carbon-based electrodes
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  • H01M50/10—Primary casings, jackets or wrappings of a single cell or a single battery
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  • H01M50/109—Primary casings, jackets or wrappings of a single cell or a single battery characterised by their shape or physical structure of button or coin shape
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  • H01M50/116—Primary casings, jackets or wrappings of a single cell or a single battery characterised by the material
  • H01M50/117—Inorganic material
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  • H01M50/10—Primary casings, jackets or wrappings of a single cell or a single battery
  • H01M50/138—Primary casings, jackets or wrappings of a single cell or a single battery adapted for specific cells, e.g. electrochemical cells operating at high temperature
  • H01M50/1385—Hybrid cells
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  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
  • H01M50/289—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders characterised by spacing elements or positioning means within frames, racks or packs
  • H01M50/291—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders characterised by spacing elements or positioning means within frames, racks or packs characterised by their shape
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  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/50—Current conducting connections for cells or batteries
  • H01M50/543—Terminals
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  • H01M6/5033—Methods or arrangements for servicing or maintenance, e.g. for maintaining operating temperature used as charging means for another battery
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  • H01M8/0204—Non-porous and characterised by the material
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  • H01M10/44—Methods for charging or discharging
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  • H01M4/00—Electrodes
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  • H01M2004/021—Physical characteristics, e.g. porosity, surface area
• • H—ELECTRICITY
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  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
  • H01M2004/8678—Inert electrodes with catalytic activity, e.g. for fuel cells characterised by the polarity
  • H01M2004/8689—Positive electrodes
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  • H01M2010/0495—Nanobatteries
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  • H01M2200/20—Pressure-sensitive devices
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  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
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  • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
  • H01M4/90—Selection of catalytic material
  • H01M4/9016—Oxides, hydroxides or oxygenated metallic salts
• • H—ELECTRICITY
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  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/10—Primary casings, jackets or wrappings of a single cell or a single battery
  • H01M50/102—Primary casings, jackets or wrappings of a single cell or a single battery characterised by their shape or physical structure
  • H01M50/103—Primary casings, jackets or wrappings of a single cell or a single battery characterised by their shape or physical structure prismatic or rectangular
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  • H01M8/0204—Non-porous and characterised by the material
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  • H01M8/04089—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants
• • 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
• • 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
  • Y02E60/30—Hydrogen technology
  • Y02E60/50—Fuel cells
• • 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
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
  • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

• the present invention relates to alkaline electrochemical cells, particularly to metal-air cells. Even more particularly, the invention relates to such cells in low temperature and low humidity environments. Still more particularly, the invention relates to the application of pressure to such cells to improve low temperature and low humidity performance, particularly, the voltage delay phenomenon.
• alkaline batteries One problem associated with alkaline batteries is that their performance is adversely affected by exposure to cold temperatures.
• metal-air cells the performance is adversely affected by low humidity environments due to the escape of moisture from the cell's air holes. Exposure to cold temperatures slows the electrochemical reactions of the battery cell, which can have a similar effect. These ambient conditions cause, in effect, premature aging of the battery by causing the voltage to drop, early in the discharge history of the cell, to a level below the minimum required for the proper operation of battery powered device.
• the invention provides an alkaline battery cell capable of increased performance by providing external pressure on the cell.
• the effect is appreciable in low humidity conditions where air cells tend to dry out.
• enhanced performance and tolerance of low- humidity provides a benefit to regular alkaline cells as well as metal-air cells, because the external pressure permits the use of a higher ratio of electrode material to electrolyte, thereby extending the cell's power capacity.
• a battery cell may be designed to apply external pressure to elevate the pressure within the battery cell. This produces the unexpected result of increasing the metal-air battery cell's performance in room and cold temperature environments. Elevated pressure can be applied to the materials involved in the metal-air electrochemical process by various mechanisms. Pressure can be created, for example, by the use of indentations in the battery cell after the cell is manufactured. Alternatively, it can be generated by the use of tightened straps that surround the battery cell, springs or parallel plates that compress the battery cell, or by other external pressure sources on the battery cell. Alternatively, pressure is created in the battery cell during construction of the battery cell, such that the battery cell casing elements apply pressure to the battery cell's contents.
• Alkaline cells can expand due to accumulation of hydrogen gas resulting from parasitic oxidation of the metal electrode or expansion due to the metal transforming to its oxide. Such increases in pressure can cause a rupture or leak.
• indentations or other housing features can be shaped to deform progressively when pressure from the cell gets too high so that a constant internal pressure can be maintained. This helps to prevent the battery cell from failing or leaking due to uncontrolled expansion.
• the deformation provided by an indentation can be designed so that it either progressively collapses under an over-pressure condition or undergoes paroxysmal collapse to protect the cell from rupture.
• the progressive collapse (or reversal) of the indentation has the advantage of permitting a constant pressure to be maintained despite progressive expansion of the cell during discharge due to zinc oxide formation.
• the battery cell can be made flexible and/or strong enough to accommodate the increased pressure.
• a venting system can alternatively be added to help maintain optimum pressure within the battery cell by permitting release of hydrogen gas.
• FIG. 1 A is a perspective view of a prismatic metal-air battery cell.
• FIG. IB is a section view of the embodiment of FIG. 1 A.
• FIG. 2 is a perspective view of a prismatic metal-air battery cell with external straps and blocks.
• FIG. 3 A is a side view of the prismatic metal-air battery cell with indentations.
• FIG. 3B is a top view of a prismatic metal-air battery cell with indentations.
• FIG. 3C is a top view of a prismatic metal-air battery cell with indentations.
• FIG. 3D is a cross-sectional view of the prismatic metal-air battery cell shown in FIG. 3C.
• FIG. 3E is a side view of a prismatic metal-air battery cell with indentations along the battery cell side walls.
• FIG. 3F is a side view of a prismatic metal-air battery cell with parallel plates compressing the battery cell.
• FIG. 3G is a top view of a prismatic metal-air battery cell with parallel plates compressing the battery cell.
• FIG. 4 is a partial cross-sectional view of a prismatic metal-air battery cell with expandable foam.
• FIG. 5 is a cross-sectional view of an alternative embodiment of the invention.
• the embodiment utilizes a snap-fitting strap to increase pressure within the battery cell.
• FIGS. 6 and 7 show typical curves demonstrating the voltage delay phenomena.
• FIGS. 8 and 9 show the effect of pressure on battery cell voltage and voltage delay.
• FIGS. 10 and 11 show the effect of pressure on battery cell voltage, recovery rate and voltage delay.
• FIGS. 12-14 show the effect of pressure on voltage delay.
• FIGS. 15 and 16 show the effect of pressure at 30% discharge after three days storage at 20% relative humidity.
• FIG. 17 shows typical discharge curves of pressurized and unpressurized battery cells at low temperature.
• FIG. 18 shows the discharge curves of battery cells subject to a range of external pressure.
• Pressurized battery cells provide substantially higher voltages over their discharge history than unpressurized battery cells. Pressure also reduces the voltage delay phenomenon. This problem is characterized by a voltage drop immediately after a long period of open circuit voltage condition or during the use of a new battery cell. Pressure also improves the performance of battery cells, particularly metal-air cells used in low humidity environments.
• a prism- shaped zinc-air cell 100 has a generally planar elements including an outer casing element 125 on a cathode side 100A of the cell 100, a diffuser 20, air cathode active layer 45, separator 55, anode 30, and outer casing element 141 on the anode side 100B of the battery cell 100. Air gases diffuse into and out of the cell through holes 50 in the casing.
• the internal layers of the battery cell 100, including diffuser 20, air cathode 45, separator 55, and anode 30, are all sandwiched between the outer casing elements 125 and 141.
• the anode includes finely divided metal (e.g., zinc powder) in a slurry formed with potassium hydroxide and a gelling agent as described below.
• the outer casing elements are substantially rectangular with each having a major surface 110 and 140.
• the outer casing elements can be constructed from either metal or plastic.
• one aspect of the present invention is to create and control pressure within battery cells. While the application of pressure to prismatic shaped metal-air battery cells is described below, the invention can be used in all types of battery cells, including alkaline battery cells.
• pressure is applied by wrapping the battery cell 100 with external straps 135.
• straps 135 are placed around the battery cell 100 over pressure blocks 130. The straps 135 are tightened and the blocks 130 compress the major surface 110 of the cathode casing element, creating pressure within the battery cell 100.
• the blocks 130 can be placed so as to compress the major surface of the anode casing element (not shown).
• indentations 145 are created on the major surface 140 of the anode casing element 141 to create pressure within the battery cell 100. These indentations 145 increase pressure within the battery cell 100, as well as making the major surface 140 of the anode casing element 141 more ridged and less susceptible to deformation under pressure.
• the indentations 145 can be placed vertically along the width or length of the major surface 140 of the anode casing element 141, or diagonally across this major surface 140. Moreover, the indentations can alternatively be located on the major surface 110 of the cathode casing element 125.
• FIGS. 3C and 3D show indentations 150 punched at several places across the major surface 140 of the anode casing element 141. Additionally, the major surface of the cathode casing element (not shown) can be indented in this manner.
• FIG. 3E shows indentations 155 on the side walls 156 of the battery cell 100. These indentations 155 can be located along the length and/or width of the battery cell 100.
• two plates 165 are used to sandwiched the battery cell 100. Straps 170, or some other fastening means such as screws, compress the plates 165 into the battery cell 100 generating pressure within the battery cell 100. Although not shown in the drawings, cutouts are made in the plate on the cathode side of the battery cell. This ensures that air is supplied to the air access holes in the battery cell.
• Pressure can also be generated during construction of the battery cell 100. This pressure allows the battery cell casing elements to apply pressure to the battery cell's 100 contents.
• the battery cell casing elements can be crimped or otherwise attached so as to create this pressure.
• the expansion of the battery cell 100 due to zinc oxide formation can create and maintain pressure within the battery cell 100.
• the battery cell outer casing elements apply pressure to the battery cell's 100 contents.
• the battery cell casing elements may be formed in such a way as to yield at a certain pressure, allowing continued expansion.
• expandable foam can be used in combination with a pressure control mechanism in the battery cell 100. Such a mechanism could include a vent or valve to relieve pressure above a certain amount).
• expandable foam 175 can be used in the present invention to maintain a given pressure within the battery cell 100.
• the foam 175 is placed between the anode material 176 and the major surface 140 of the anode casing element 141.
• the expandable foam 175 is selected so as to maintain a set elevated pressure in the battery cell 100.
• the foam 175 is designed to collapse at a set pressure, while a valve or vent (not shown - e ⁇ g., a pressure valve) is inserted to ensure that the pressure in the battery cell 100 does not rise above a certain pressure.
• a strap 180 is wrapped tightly around the cell 100 to elevate the pressure within the battery cell 100, while also resisting the deformation and the bulging of the battery cell 100.
• the strap 180 is snap fitted onto the battery cell 100. It is preferred that the strap 180 be made of an insulated and resilient material so that the strap 180 does not cause the battery cell 100 to short circuit.
• the outer casing elements can contain recesses shaped to fit the strap 180 so that the strap 180 is at least partially embedded in the cathode and/or anode casing elements. Depending on the configuration of the battery cell 100, the strap 180 can also assist in the attachment of the battery cell outer casing elements.
• Voltage delay is characterized by a voltage drop immediately after current is applied, usually after a long period in open circuit voltage condition or after the battery cell's construction (fresh battery cell). The battery cell voltage then recovers within a few minutes and stabilizes. This problem is caused mainly at the air electrode and separator side of the battery cell, probably as a result of water evaporation and/or by electrolyte rejection. External pressure has been found to decrease the voltage delay and increase the battery cell voltage.
• the anode mixture was prepared as follows:
• the dosed blend contained 56.0:0.5:43.5 % (w/w %) of zinc powder, Carbopol and
• the cathode was prepared as follows:
• the active mass was then spread evenly over a nickel mesh (40 X 40 mesh, 0.005 mm diameter nickel from National Standard) and pressed to form the active layer of the electrode.
• a porous PTFE sheet was then pressed on to one side of the active layer;
• the air electrode was then laminated with a non-woven separator and a microporous polypropylene film (grade 3501 from Celgard®) on the side distal from the PTFE sheet.
• the lamination was effected using PVA (polyvinyl alcohol from Aldrich Chemical) as a glue; and 5.
• PVA polyvinyl alcohol from Aldrich Chemical
• the air electrode was placed inside the cell's cathode casing and the casing filled with the zinc gel prepared above.
• the anode casing was placed above the cathode casing.
• metal casings were used, the cell was closed by crimping the cathode casing to the anode casing with a nylon grommet positioned between them to prevent electrical shorting.
• the cells were made of plastic, the cell was closed by gluing the casings together.
• the plastic cell also contained a nickel wire mesh current collector for the zinc anode which can be omitted from metal cells.
• GSM Global Systems Mobile
• the GSM profile consisted of repetitive cycles of 1.34 A for 0.5 millisecond followed by 0.078 A for 4.1 milliseconds for the duration of the discharge.
• the discharge was carried out in increments of 10 or 20% depth of discharge (DOD) every two days.
• OCV open circuit voltage
• RH 50% relative humidity
• RT room temperature
• the discharges were measured using a Maccor 4000 Gen 4 Battery Tester. Impedance was measured at 1 kHz with a Hewlett-Packard milli-ohmeter. Temperature and humidity were controlled using a Thermatron 2800 Environmental Chamber.
• the cells were pressed between the metal plates of a jig with a plastic insulating layer between the plates and the cells. Pressure was controlled using screws connecting the plates to the jig. The force applied was generally between 39.2-58.8 N equivalent to a pressure of about 03.4-5.2 N/cm 2 .
• the values of the voltage delay were about 35 mV at 0-20% discharge.
• the maximum voltage delay values were about 70 mV between 20%-40% discharge. This value decreased after 40% discharge to 25 mV at 70% discharge.
• Table 1 shows that the voltage never dropped below 0.9 V, the minimum acceptable voltage for cells intended for a cellular phone battery pack.
• the voltage delay was about 35 mV at 0 - 20% discharge.
• the maximum voltage delay was about 70 mV which occurred between 20 - 40% discharge. This maximum decreased to 25 mV at 70% discharge.
• FIGS. 8 and 9 show the effect of pressure on battery cell voltage and voltage delay. It can be seen that the shape of the curve is similar in both pressurized and unpressurized metal- air battery cells. However, the battery cell voltage was higher for the pressed cell and the voltage delay lower compared to the unpressed cell. In addition, it can be seen that the recovery rate of the voltage in pressurized battery cells is faster.
• Table 2 The results of the effect of pressure on battery cell voltage and voltage delay are summarized in table 2.
• V mm the lowest voltage of V mm was obtained at 10% discharge. This value was lower than 0.9 V, which is a practical lower limit for certain applications, for example, cellular phone applications.
• the maximum voltage delay was 240 mV which occurred at 10% depth of discharge.
• the voltage delay problem is caused by water evaporation and/or electrolyte rejection from the air electrode and separator side.
• the fact that the battery cell voltage reaches a minimum after about six seconds suggests that the voltage delay problem is not only an IR (voltage) problem but also a diffusion problem (probably water diffusion). It appears that after 50% discharge this problem becomes insignificant. This is probably due to zinc oxide and hydroxide precipitation having a higher molar volume (about triple) than zinc. The volume occupied by these solids increases with percentage discharge, pushing the electrolyte towards the air electrode and the voltage delay is reduced.
• the voltage delay value reaches a maximum between 10%-30% discharge. This can be related to the voltage dip caused by the zinc electrode. From the literature, the impedance rises by about 20% at the stage when the dip voltage is reaching minimum. In CB this dip reaching minimum typically at 20% discharge. It can be concluded that this dip voltage delay is obtained at 10% discharge. It can be concluded that this dip is "moved" to an early discharge stage by external pressure. The voltage delay in plastic battery cells is much higher than in metal battery cells.
• EXAMPLE 2 Metal cells in this example were prepared as described in Example 1. Except where otherwise noted, the methods and procedures used in Example 1 were also applied here. The purpose of these experiments was to determine the effect of pressure on cells kept at low relative humidities.
• Example 1 Metal cells in this example were prepared as described in Example 1. Except where otherwise noted, the methods and procedures used in Example 1 were also applied here. The purpose of these experiment was to determine the effect of pressure on cells kept at low temperature and after storage.
• FIG. 17 shows typical discharge curves of pressurized and unpressurized battery cells. It can be seen that at the beginning of discharge there is no difference between the two curves; however, after 1.5 hours the voltage of the pressurized battery cell starts to rise and is maintained at 890 mV, whereas the voltage of the unpressurized battery cell decreases further and stabilized at 820 mV. Additionally, it appears that there is no difference in the cells' capacity (1.7 Ah) between pressed and unpressed cells.
• FIG. 18 shows the discharge curves of these battery cells at 0°C, GSM. It can be seen that when no pressure was applied, the voltage was maintained at about 940 raV when there is a slightly difference between the battery cells voltage. This relatively high voltage is caused probably as a result of a change in battery cells - contains 5.9 g gel instead of 5.5 g. After pressure was applied, the voltage starts to rise and maintained at 970 mV.
• the impedance of the battery cells were measured. It appears than when pressure was applied, the impedance dropped by 20% (usually from 0.12 to 0.1 ohm). When the pressure was released, the impedance rose to its initial value (see table 11).

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• 1999
  • 1999-11-30 AU AU21591/00A patent/AU2159100A/en not_active Abandoned
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