CA1093633A - Cathodes for electrolyte cells - Google Patents
Cathodes for electrolyte cellsInfo
- Publication number
- CA1093633A CA1093633A CA300,260A CA300260A CA1093633A CA 1093633 A CA1093633 A CA 1093633A CA 300260 A CA300260 A CA 300260A CA 1093633 A CA1093633 A CA 1093633A
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- CA
- Canada
- Prior art keywords
- cells
- cathode
- cell
- electrolyte
- solid
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- 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
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/581—Chalcogenides or intercalation compounds thereof
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M6/00—Primary cells; Manufacture thereof
- H01M6/14—Cells with non-aqueous electrolyte
- H01M6/18—Cells with non-aqueous electrolyte with solid electrolyte
-
- 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 & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Inorganic Chemistry (AREA)
- Secondary Cells (AREA)
- Primary Cells (AREA)
- Battery Electrode And Active Subsutance (AREA)
- Conductive Materials (AREA)
Abstract
NOVEL CATHODES FOR
SOLID ELECTROLYTE CELLS
ABSTRACT
High energy density solid state cells using as a cathode, ionically and electronically conductive dischargeable metal chalcogenides.
SOLID ELECTROLYTE CELLS
ABSTRACT
High energy density solid state cells using as a cathode, ionically and electronically conductive dischargeable metal chalcogenides.
Description
10~3~33 This invention relates to high energy density cells utilizing solid electrolytes, solid active metal anodes and novel solid cathodes, and more particularly to such cells in which the cathodes contain an active material which is both ionically and electronically conductive.
Recently the state of electronics has achieved a high degree of sophistication especially in regard to devices utilizing integrated circuit chips which have been proliferating in items such as quartz crystal watches, calculators, cameras, pacemakers and the like. Miniaturization of these devices as well as low power drainage and relatively long lives under all types of conditions has resulted in a demand for power sources which have characteristics of rugged construction, long shelf life, high reliability, high energy density and an operating capability over a wide range of temperatures as well as concomitant miniaturization of the power source. These requirements pose problems for conventional cells having solution or even paste type electrolytes especially with regard to shelf life. The electrode materials in such cells may react with the electrolyte solutions and tend therefore to self discharge after periods of time which are relatively short when compared to the potential life of solid state batteries. There may also be evolution of gases in such cells which could force the electrolyte to leak out of the battery seals, thus corroding other components in the circuit which in sophisticated componentry can be very damaging. Increasing closure ~093~i33~
reliability is both bulky and costly and will not eliminate the problem of self discharge. Additionally, solution cells have a limi~edoperating temperature range dependent upon the freezing and boiling points of the contained solutions.
Success in meeting the above demands without the drawbacks of solution electrolyte systems has been achieved with the use of solid electrolyte and electrode cells or solid state cells which do not evolve gases, self discharge on long standing or have electrolyte leakage problems. These systems however have had their own particular limitations and drawbacks not inherent in solution electrolyte cells.
Ideally a cell should have a high voltage, a high energy density, and a high current capability. Prior art solld state cells have however been deficient in one or more of the above desirable characteristics.
A first requirement and an important part of the operation of any solid state cell is the choice of solid electrolyte. In order to provide good current capability a solid electrolyte should have a high ionic conductivity which enables the transport of ions through defects in the crystalline electrolyte structure of the electrode-electrolyte system. An additional, and one of the most important require-ments for a solid electrolyte , is that it must be virtually solely an ionic conductor. Conductivity due to the mobility of electrons must be neglible because otherwise the resulting partial internal short circuiting would result in the consumption of electrode materials even under open circuit conditions.
1093~i33~
Solution electrolyte cells inc]ude an electronically non-con-ductive separator between the electrode elements to prevent such a short circuit, whereas solid state cells utilize the solid electrolyte as both electronic separator and the ionic conductive species.
~ Iigh current capabilities for solid state cells have been attained with the use of materials which are solely ionic conductors such as RbAg4Is (.27 ohm 1 cm 1 room temperature con-ductivity). However these conductors are only useful as electro-lytes in cells having low voltages and energy densities. As an example, a solid state Ag/RbAg4I5/RbI3 cell is dischargeable at 40 mA/cm2 at room temperature but with about 0.2 Whr/in3 and an OCV of 0.66V. High energy density and high voltage anodic materials such as lithium are chemically reactive with such con-ductors thereby precluding the use of these conductors in such cells. Electrolytes which are chemlcally compatible with the high energy density and high voltage anode materials such as LiI, even when doped for greater conductivity, do not exceed a conductivity of 5 x 10 5 ohm 1 cm 1 at room temperature. Thus, high energy density cells with an energy density ranging from about 5-10 whr/in3 and a voltage at about 1.9 volts for a Li/LiI-doped/PbI, PbS,-Pb cell currently being produced are precluded from having an effective high current capability above 50t~A/cm 2 at room temperature. A further aggravation of the reduced current capability of high energy density cells is the low conductivity (both electronic and - ----------- ---- -M-332~D
1~3~i33 ionic) of active cathode materials. Conductivity enhancers such as graphite for electronic conductivity and electrolyte for ionic conductivity,while increasing the current capability of the cell to the maximum allowed by the conductivity of the electrolyte, reduce the energy density of the cell because of their volume.
Commercial feasibility in production of the electro-lyte material is another factor to be considered in the con-struction of solid state cells. Thus, the physical properties of electrolytes such as BaMg5S5 and BaMg5Se6, which are compatible with a magnesium but not a lithium anode, and sodium beta aluminas such as Na20 11 A12O3, which are compatible with sodium anodes, will preclude the fabrication of cells having a high energy density or current capability even when costly production steps are taken. These electrolytes have ceramic characteristics making them difficult to work with especially in manufacturing processes involving grinding and pelletization with such processes requiring a firing step for structural integrity. Furthermore, the glazed material so formed inhibits good surface contact with the electrodes with a result of poor conductivity leading to poor cell performance. These electrolytes are thus typically used in cells with molten electrodes.
It is therefore an object of the present invention to increasethe conductivity of the cathode of solid state cells in conjunction with high energy density anodes and compat-ible electrolytes such that there is an increase in energy den-sity without current capability losses resulting from the - addition of inert conductive materials, while maintaining r~
^
10~3633 chemical stability between the cell components.
Generally the present invention involves the formation of the cathode of a solid state cell with a material which has the characteristics of being both ionically and electronically conductive as well as being able to function as an active ca~hode material. Normally cathodes require the incorporation of substantial amounts (e.g. over 20 percent by weight) of an ionic conductor such as that used as the electrolyte in order to facilitate ionic flow in the cathode during the cell reaction.
This is especially true if the cathodic material is an electronic conductor since otherwise a reduction product would form at the cathode-electrolyte interface which would eventually block off a substantial amount of the ionic flow during discharge. How-ever the incorporated ionic conductors in prior art cells have not generally been cathode active materials with the result of significant capacity loss. Additionally, cathode active materials which are poor electronic conductors as well require the further incorporation of electronically conductive materials which further reduces the cells energy capacity. By combining the functions of electronic and ionic conductivity with cathode activity a higher energy density and current capability is attained with the need for space wasting conductors being obviated.
Examples of materials having the requisite character-istics of ionic and electronic conductivity and which are cathodically active as well as being compatible with electrolytes used in high energy density cells include the following metal ' chalcogenides: CoTe2, Cr2S3, HfS2, HfSe2, HfTe2, IrTe2, MoS2, 1093~c;33 MoSe2, MoTe2, NbS2, NbSe2, NbTe2, NiTe2, PtS2, PtSe2, PtTe2, SnS2, SnSSe, SnSe2, TaS2, TaSe2, TaTe2, TiS2, TiSe2, TiTe2, S2, VSe2, VTe2, WS2, WSe2, WT2, zrS2, Zrse2~ and ZrTe2, wherein the chalcogenide is a sulfide, selenide, telluride or combination.
Also included are the non-stoichiometric metal chal-cogenide compounds such as LixTiS2 where x~l, whieh to some extent contain the complexed form of one of the cathode materials with the anodic cation and which are believed to be intermediate reaction products during cell discharge.
In order for the ionically-electronically conductive cathode active material to be commercially useful in high voltage cells such as lithium anodes it should be able to provide a voltage couple with lithium of at least an O.C.V. of 1.5 volts and preferably above 2 volts.
A further criteria for the above cathodic material is that both the ionic and electronic conductivities of the cathode active material should range between lO~l~nd 102 ohm~l cm~l with a preferred ionic conductivity of more than 10-6 and an electronie eonduetivity greater than 10-1,all at room temperature.
In addition, and most importantly, the ionically-eleetronieally eonduetive,aetive eathode material must be eom-patible with the solid electrolytes used in the high energy density eells.
The solid electrolytes used in high energy density lithium eells are lithium salts andhave room temperature ionie con-duetivities greater than 1 x 10-9 ohm~l cm~l These salts can eithe be in the pure form or combined with conductivity enhancers such that the current capability is improved thereby. Examples of lithium salts having the requisite conductivity for meaningful cell utilization include lith:ium iodide (LiI) and lithium iodide admixed wi-th lithium hydroxide (LioH) and aluminum oxide (A12O3) with the latter mixture being referred to as LLA and disclosed in U.S. patent no. 3,713,897.
High energy density solid electrolyte cells may have as their anodes materials similar to lithium which have high voltage and low electrochemical equivalent weight character-istics. Suitable anodic materials include metals from Groups IA and IIA of the Periodic Table such as sodium, potassium, beryllium, magnesium and calcium as well as aluminum from Group IIIA and other metals above hydrogen in the EMF series.
Cells with other anodes can utilize correspondingsalts as electrolytes such as sodium salts for a cell with a sodium anode. Additionally, electrolyte salts with useful conductivities and having a cation of a metal~lower EMF than that of the anode metal may also be useful.
It is postulated that the aforementioned ionically-electronically conductive cathode active materials react with the ions of the anode (e.g. lithium cations) to form a non-stoichiometric complex during the discharge of the cell. This complexing of cations allows them to move from site to site thereby providing ionic conductivity. Additionally the above compounds provide the free electrons necessary for electronic conductivity.
R limiting factor in solid state cell performance is the conductivity of the cell reaction product. A low conductivity M~
- ~0S~3~ 3 product results in large internal resistance losses which effectively terminate cell usefulness. Thus a further advantage of cells having the above ionically-electronically conductive cathode active material is that the complexed reaction product retains conductivity thereby enabling full utilization of Lhe cathode.
A small amount of electrolyte can also be included in the cathode structure in order to blur the interface between cathode and electrolyte thereby providing moreintimate electrical contact between the cathode and the electrolyte.
This enables the cell to operate at higher current drains for longer periods of time. Additionally the electrolyte inclusion can increase the ionic conductivity of the cathode should the ionically conductive cathode active material have a lower conductivity than that of the electrolyte. This incl-lsion however, if made, should not exceed 10% by weight since greater amounts would merely decrease the energy density of the cell with little if any further tradeoff in terms of current drain capacity. Accordingly the cathode should include at least 90%
by weight of the ionically-electronically conductive cathode active material.
In order that the present invention be more completely understood the following examples are given with all parts being by weight unless otherwise specified. The examples are only for illustrative purposes and should not be taken as limitations of either cell construction or of materials con-tained therein.
5 G ~--J
` ` 10~3~;33 A solid state electrochemical cell is formed using a lithium metal disc having dimensions of about 1.47 cm2 contact surface area by about 0.01 cm thickness; a cathode disc having dimensions of about 1.71 cm2 contact surface area by about 0.02 cm thickness consisting of titanium disulfide (TiS2) and weighing about 100 mg, and a solid electrolyte with the same dimensions as the cathode and consis~lng of LiI, LioH, and A1203 in a 4:1:2 ratio. The electrolyte is first pressed with the cathode at a pressure of about 100,000 psi. The anode is then pressed to the other side of the electrolyte using about 50,000 psi. The resulting cell is discharged at a temperature of 72C under a load of lOk~. The cell realizes 14 milliamp hours (mA~) to 2 volts, 21 mAH to 1.5 volts, and about 24 mAH to 1 volt.
The titanium disulfide in the above Example is both a good ionic and electronic conductor (10-5 ohm~l cm~l ionic conductivity and greater than 10~1 ohm~l cm~l electronic con-ductivity at room temperature) and thus constitutes the cathode without conductive additives. The titanium disulfide functions as a reactive species in the cell reaction with the lithium cations to form the non-stoichiometric LixTiS2 which is also ionically and electronically conductive thus further ameliorating the problem of incomplete cell discharge resulting from non-conductive reaction products choking off further cell reaction.
The ionically-electronically conductive, cathode active materials can be admixed with one another to form a cathode as in the following EXAMPLES.
A solid state cell :is made in accordance with EXAMPLE 1 but with the cathode having a contact surface area of 1.82 cm2 and comprising a 1:1 mixture of titanium disulfide and molybdenum disulfide weighing about 50 mg. The cell is discharged at 27C under a load of 18~A. The cell realizes
Recently the state of electronics has achieved a high degree of sophistication especially in regard to devices utilizing integrated circuit chips which have been proliferating in items such as quartz crystal watches, calculators, cameras, pacemakers and the like. Miniaturization of these devices as well as low power drainage and relatively long lives under all types of conditions has resulted in a demand for power sources which have characteristics of rugged construction, long shelf life, high reliability, high energy density and an operating capability over a wide range of temperatures as well as concomitant miniaturization of the power source. These requirements pose problems for conventional cells having solution or even paste type electrolytes especially with regard to shelf life. The electrode materials in such cells may react with the electrolyte solutions and tend therefore to self discharge after periods of time which are relatively short when compared to the potential life of solid state batteries. There may also be evolution of gases in such cells which could force the electrolyte to leak out of the battery seals, thus corroding other components in the circuit which in sophisticated componentry can be very damaging. Increasing closure ~093~i33~
reliability is both bulky and costly and will not eliminate the problem of self discharge. Additionally, solution cells have a limi~edoperating temperature range dependent upon the freezing and boiling points of the contained solutions.
Success in meeting the above demands without the drawbacks of solution electrolyte systems has been achieved with the use of solid electrolyte and electrode cells or solid state cells which do not evolve gases, self discharge on long standing or have electrolyte leakage problems. These systems however have had their own particular limitations and drawbacks not inherent in solution electrolyte cells.
Ideally a cell should have a high voltage, a high energy density, and a high current capability. Prior art solld state cells have however been deficient in one or more of the above desirable characteristics.
A first requirement and an important part of the operation of any solid state cell is the choice of solid electrolyte. In order to provide good current capability a solid electrolyte should have a high ionic conductivity which enables the transport of ions through defects in the crystalline electrolyte structure of the electrode-electrolyte system. An additional, and one of the most important require-ments for a solid electrolyte , is that it must be virtually solely an ionic conductor. Conductivity due to the mobility of electrons must be neglible because otherwise the resulting partial internal short circuiting would result in the consumption of electrode materials even under open circuit conditions.
1093~i33~
Solution electrolyte cells inc]ude an electronically non-con-ductive separator between the electrode elements to prevent such a short circuit, whereas solid state cells utilize the solid electrolyte as both electronic separator and the ionic conductive species.
~ Iigh current capabilities for solid state cells have been attained with the use of materials which are solely ionic conductors such as RbAg4Is (.27 ohm 1 cm 1 room temperature con-ductivity). However these conductors are only useful as electro-lytes in cells having low voltages and energy densities. As an example, a solid state Ag/RbAg4I5/RbI3 cell is dischargeable at 40 mA/cm2 at room temperature but with about 0.2 Whr/in3 and an OCV of 0.66V. High energy density and high voltage anodic materials such as lithium are chemically reactive with such con-ductors thereby precluding the use of these conductors in such cells. Electrolytes which are chemlcally compatible with the high energy density and high voltage anode materials such as LiI, even when doped for greater conductivity, do not exceed a conductivity of 5 x 10 5 ohm 1 cm 1 at room temperature. Thus, high energy density cells with an energy density ranging from about 5-10 whr/in3 and a voltage at about 1.9 volts for a Li/LiI-doped/PbI, PbS,-Pb cell currently being produced are precluded from having an effective high current capability above 50t~A/cm 2 at room temperature. A further aggravation of the reduced current capability of high energy density cells is the low conductivity (both electronic and - ----------- ---- -M-332~D
1~3~i33 ionic) of active cathode materials. Conductivity enhancers such as graphite for electronic conductivity and electrolyte for ionic conductivity,while increasing the current capability of the cell to the maximum allowed by the conductivity of the electrolyte, reduce the energy density of the cell because of their volume.
Commercial feasibility in production of the electro-lyte material is another factor to be considered in the con-struction of solid state cells. Thus, the physical properties of electrolytes such as BaMg5S5 and BaMg5Se6, which are compatible with a magnesium but not a lithium anode, and sodium beta aluminas such as Na20 11 A12O3, which are compatible with sodium anodes, will preclude the fabrication of cells having a high energy density or current capability even when costly production steps are taken. These electrolytes have ceramic characteristics making them difficult to work with especially in manufacturing processes involving grinding and pelletization with such processes requiring a firing step for structural integrity. Furthermore, the glazed material so formed inhibits good surface contact with the electrodes with a result of poor conductivity leading to poor cell performance. These electrolytes are thus typically used in cells with molten electrodes.
It is therefore an object of the present invention to increasethe conductivity of the cathode of solid state cells in conjunction with high energy density anodes and compat-ible electrolytes such that there is an increase in energy den-sity without current capability losses resulting from the - addition of inert conductive materials, while maintaining r~
^
10~3633 chemical stability between the cell components.
Generally the present invention involves the formation of the cathode of a solid state cell with a material which has the characteristics of being both ionically and electronically conductive as well as being able to function as an active ca~hode material. Normally cathodes require the incorporation of substantial amounts (e.g. over 20 percent by weight) of an ionic conductor such as that used as the electrolyte in order to facilitate ionic flow in the cathode during the cell reaction.
This is especially true if the cathodic material is an electronic conductor since otherwise a reduction product would form at the cathode-electrolyte interface which would eventually block off a substantial amount of the ionic flow during discharge. How-ever the incorporated ionic conductors in prior art cells have not generally been cathode active materials with the result of significant capacity loss. Additionally, cathode active materials which are poor electronic conductors as well require the further incorporation of electronically conductive materials which further reduces the cells energy capacity. By combining the functions of electronic and ionic conductivity with cathode activity a higher energy density and current capability is attained with the need for space wasting conductors being obviated.
Examples of materials having the requisite character-istics of ionic and electronic conductivity and which are cathodically active as well as being compatible with electrolytes used in high energy density cells include the following metal ' chalcogenides: CoTe2, Cr2S3, HfS2, HfSe2, HfTe2, IrTe2, MoS2, 1093~c;33 MoSe2, MoTe2, NbS2, NbSe2, NbTe2, NiTe2, PtS2, PtSe2, PtTe2, SnS2, SnSSe, SnSe2, TaS2, TaSe2, TaTe2, TiS2, TiSe2, TiTe2, S2, VSe2, VTe2, WS2, WSe2, WT2, zrS2, Zrse2~ and ZrTe2, wherein the chalcogenide is a sulfide, selenide, telluride or combination.
Also included are the non-stoichiometric metal chal-cogenide compounds such as LixTiS2 where x~l, whieh to some extent contain the complexed form of one of the cathode materials with the anodic cation and which are believed to be intermediate reaction products during cell discharge.
In order for the ionically-electronically conductive cathode active material to be commercially useful in high voltage cells such as lithium anodes it should be able to provide a voltage couple with lithium of at least an O.C.V. of 1.5 volts and preferably above 2 volts.
A further criteria for the above cathodic material is that both the ionic and electronic conductivities of the cathode active material should range between lO~l~nd 102 ohm~l cm~l with a preferred ionic conductivity of more than 10-6 and an electronie eonduetivity greater than 10-1,all at room temperature.
In addition, and most importantly, the ionically-eleetronieally eonduetive,aetive eathode material must be eom-patible with the solid electrolytes used in the high energy density eells.
The solid electrolytes used in high energy density lithium eells are lithium salts andhave room temperature ionie con-duetivities greater than 1 x 10-9 ohm~l cm~l These salts can eithe be in the pure form or combined with conductivity enhancers such that the current capability is improved thereby. Examples of lithium salts having the requisite conductivity for meaningful cell utilization include lith:ium iodide (LiI) and lithium iodide admixed wi-th lithium hydroxide (LioH) and aluminum oxide (A12O3) with the latter mixture being referred to as LLA and disclosed in U.S. patent no. 3,713,897.
High energy density solid electrolyte cells may have as their anodes materials similar to lithium which have high voltage and low electrochemical equivalent weight character-istics. Suitable anodic materials include metals from Groups IA and IIA of the Periodic Table such as sodium, potassium, beryllium, magnesium and calcium as well as aluminum from Group IIIA and other metals above hydrogen in the EMF series.
Cells with other anodes can utilize correspondingsalts as electrolytes such as sodium salts for a cell with a sodium anode. Additionally, electrolyte salts with useful conductivities and having a cation of a metal~lower EMF than that of the anode metal may also be useful.
It is postulated that the aforementioned ionically-electronically conductive cathode active materials react with the ions of the anode (e.g. lithium cations) to form a non-stoichiometric complex during the discharge of the cell. This complexing of cations allows them to move from site to site thereby providing ionic conductivity. Additionally the above compounds provide the free electrons necessary for electronic conductivity.
R limiting factor in solid state cell performance is the conductivity of the cell reaction product. A low conductivity M~
- ~0S~3~ 3 product results in large internal resistance losses which effectively terminate cell usefulness. Thus a further advantage of cells having the above ionically-electronically conductive cathode active material is that the complexed reaction product retains conductivity thereby enabling full utilization of Lhe cathode.
A small amount of electrolyte can also be included in the cathode structure in order to blur the interface between cathode and electrolyte thereby providing moreintimate electrical contact between the cathode and the electrolyte.
This enables the cell to operate at higher current drains for longer periods of time. Additionally the electrolyte inclusion can increase the ionic conductivity of the cathode should the ionically conductive cathode active material have a lower conductivity than that of the electrolyte. This incl-lsion however, if made, should not exceed 10% by weight since greater amounts would merely decrease the energy density of the cell with little if any further tradeoff in terms of current drain capacity. Accordingly the cathode should include at least 90%
by weight of the ionically-electronically conductive cathode active material.
In order that the present invention be more completely understood the following examples are given with all parts being by weight unless otherwise specified. The examples are only for illustrative purposes and should not be taken as limitations of either cell construction or of materials con-tained therein.
5 G ~--J
` ` 10~3~;33 A solid state electrochemical cell is formed using a lithium metal disc having dimensions of about 1.47 cm2 contact surface area by about 0.01 cm thickness; a cathode disc having dimensions of about 1.71 cm2 contact surface area by about 0.02 cm thickness consisting of titanium disulfide (TiS2) and weighing about 100 mg, and a solid electrolyte with the same dimensions as the cathode and consis~lng of LiI, LioH, and A1203 in a 4:1:2 ratio. The electrolyte is first pressed with the cathode at a pressure of about 100,000 psi. The anode is then pressed to the other side of the electrolyte using about 50,000 psi. The resulting cell is discharged at a temperature of 72C under a load of lOk~. The cell realizes 14 milliamp hours (mA~) to 2 volts, 21 mAH to 1.5 volts, and about 24 mAH to 1 volt.
The titanium disulfide in the above Example is both a good ionic and electronic conductor (10-5 ohm~l cm~l ionic conductivity and greater than 10~1 ohm~l cm~l electronic con-ductivity at room temperature) and thus constitutes the cathode without conductive additives. The titanium disulfide functions as a reactive species in the cell reaction with the lithium cations to form the non-stoichiometric LixTiS2 which is also ionically and electronically conductive thus further ameliorating the problem of incomplete cell discharge resulting from non-conductive reaction products choking off further cell reaction.
The ionically-electronically conductive, cathode active materials can be admixed with one another to form a cathode as in the following EXAMPLES.
A solid state cell :is made in accordance with EXAMPLE 1 but with the cathode having a contact surface area of 1.82 cm2 and comprising a 1:1 mixture of titanium disulfide and molybdenum disulfide weighing about 50 mg. The cell is discharged at 27C under a load of 18~A. The cell realizes
2.2 mAH to 2 volts, 5 mAH to 1.5 volts and 5.9 mAH to 1 volt.
A cell identical to the cell in EXAMPLE 2 is discharged at 27 C under a load of 36JUA. The cell realizes about 1 mAH
to 2 volts, about 3 m~H to 1.5 volts and about 5 mAH to 1 volt.
It is understood that other disclosed conductive metal chalcogenides can function similarly whether without any further conductive enhancers or with a maximum of 10% of conductive ;:
, materials and such materials also fall within the scope of the , ~ present invention as defined by the following claims.
A cell identical to the cell in EXAMPLE 2 is discharged at 27 C under a load of 36JUA. The cell realizes about 1 mAH
to 2 volts, about 3 m~H to 1.5 volts and about 5 mAH to 1 volt.
It is understood that other disclosed conductive metal chalcogenides can function similarly whether without any further conductive enhancers or with a maximum of 10% of conductive ;:
, materials and such materials also fall within the scope of the , ~ present invention as defined by the following claims.
Claims (5)
1. A solid state electrochemical cell comprising a solid active metal anode, a solid electrolyte and a solid cathode wherein said cathode consists of at least 90% by weight of one or more metal chalcogenides wherein the ionic and electronic conductivity of said metal chalcogenides ranges between 10-10to 102 ohm-1 cm-1 at room temperature.
2. The solid state electrochemical cell of claim 1 wherein said active metal anode is comprised of lithium.
3. The solid state electrochemical cell of claim 2 wherein said solid electrolyte is comprised of lithium iodide.
4. The solid state electrochemical cell of claim 3 wherein said solid electrolyte further includes lithium hydroxide and aluminum oxide.
5. The solid state electrochemical cell of claim 4 wherein said metal chalcogenide is titanium disulfide.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US79072677A | 1977-04-25 | 1977-04-25 | |
| US790,726 | 1977-04-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1093633A true CA1093633A (en) | 1981-01-13 |
Family
ID=25151581
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA300,260A Expired CA1093633A (en) | 1977-04-25 | 1978-04-03 | Cathodes for electrolyte cells |
Country Status (10)
| Country | Link |
|---|---|
| JP (1) | JPS53133728A (en) |
| BE (1) | BE866318A (en) |
| CA (1) | CA1093633A (en) |
| CH (1) | CH633657A5 (en) |
| DE (1) | DE2817702A1 (en) |
| DK (1) | DK177078A (en) |
| FR (1) | FR2389247B1 (en) |
| GB (1) | GB1599793A (en) |
| NL (1) | NL7804330A (en) |
| SE (1) | SE7804647L (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2508239A2 (en) * | 1981-06-17 | 1982-12-24 | Gipelec | Electrochemical cell with cation conductive vitreous electrolyte - formed by powder compaction on cathode with lithium disc superimposed |
| FR2513817B1 (en) * | 1981-09-30 | 1987-02-06 | Europ Agence Spatiale | IMPROVEMENTS ON BATTERIES |
| JPS5950027A (en) * | 1982-09-13 | 1984-03-22 | Hitachi Ltd | Thin titanium disulfide film and its formation |
| US8115282B2 (en) | 2006-07-25 | 2012-02-14 | Adesto Technology Corporation | Memory cell device and method of manufacture |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1021844A (en) * | 1973-09-10 | 1977-11-29 | Exxon Research And Engineering Company | Rechargeable battery with chalcogenide cathode |
| US3959012A (en) * | 1974-04-25 | 1976-05-25 | P. R. Mallory & Co., Inc. | Composite cathode materials for solid state batteries |
| US3988164A (en) * | 1974-04-25 | 1976-10-26 | P. R. Mallory & Co., Inc. | Cathode material for solid state batteries |
| CA1045680A (en) * | 1974-10-07 | 1979-01-02 | San-Cheng Lai | Lithium-silicon electrode for rechargeable cell |
| JPS5812676A (en) * | 1981-07-15 | 1983-01-24 | 松下電工株式会社 | Case of electric machinery |
-
1978
- 1978-04-03 CA CA300,260A patent/CA1093633A/en not_active Expired
- 1978-04-22 DE DE19782817702 patent/DE2817702A1/en not_active Ceased
- 1978-04-22 CH CH432578A patent/CH633657A5/en not_active IP Right Cessation
- 1978-04-24 DK DK177078A patent/DK177078A/en not_active Application Discontinuation
- 1978-04-24 SE SE7804647A patent/SE7804647L/en unknown
- 1978-04-24 FR FR7811998A patent/FR2389247B1/en not_active Expired
- 1978-04-24 JP JP4863278A patent/JPS53133728A/en active Pending
- 1978-04-24 NL NL7804330A patent/NL7804330A/en unknown
- 1978-04-25 BE BE2056904A patent/BE866318A/en not_active IP Right Cessation
- 1978-04-25 GB GB16383/78A patent/GB1599793A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| NL7804330A (en) | 1978-10-27 |
| FR2389247B1 (en) | 1986-03-28 |
| JPS53133728A (en) | 1978-11-21 |
| CH633657A5 (en) | 1982-12-15 |
| BE866318A (en) | 1978-08-14 |
| FR2389247A1 (en) | 1978-11-24 |
| GB1599793A (en) | 1981-10-07 |
| DK177078A (en) | 1978-10-26 |
| SE7804647L (en) | 1978-10-26 |
| DE2817702A1 (en) | 1978-10-26 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry | ||
| MKEX | Expiry |
Effective date: 19980120 |