JPS6342377B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses an active metal anode, a cathode collector, and an ionically conductive cathode/electrolyte comprising a solute dissolved in an active liquid cathode, wherein a vinyl polymer is present in the cathode/electrolyte. It concerns non-aqueous batteries dissolved in

The development of high-energy battery systems requires
Compatibility of electrolytes with desirable electrochemical properties and highly reactive anode materials such as lithium or the like is particularly required. In this type of system, the use of aqueous electrolytes is not allowed because the anode material is active enough to chemically react with water. Therefore, in order to achieve the high energy densities obtained through the use of these highly reactive anodes, it was necessary to return to research into non-aqueous electrolyte systems.

As used herein, the term "non-aqueous electrolyte" refers to, for example, a metal salt or complex salt of an element of Group A, Group A, Group A or Group A of the Periodic Table dissolved in a suitable non-aqueous solvent. Refers to the electrolyte that consists of
The term "periodic table" as used herein refers to the Chemical Rubber Company, Cleveland, Ohio.
1967-1968, 48th edition "Handbook of Chemistry and Physics" Refers to the Periodic Table of Elements as described on the endpaper.

Although a large number of solutes are known and many have been proposed for use, the selection of a suitable solvent is particularly troublesome. An ideal battery electrolyte would include a solvent/solute pair with long liquid range, high ionic conductivity, and stability. A long liquid range, ie high boiling point and low freezing point, is essential if the battery is to operate at temperatures other than ambient temperature. High ionic conductivity is essential if the battery is to have high rate performance. To provide longer life than those used in primary or secondary battery systems,
Stability is required for electrode materials, battery construction materials, and products of battery reactions.

Recently, it has been described in the literature that a few materials can be used as active cathodes in non-aqueous electrochemical cells while simultaneously acting as electrolyte carriers, ie, solvents for electrolyte salts, in non-aqueous electrochemical cells. U.S. Patent Nos. 3,475,226, 3,567,515, and
No. 3,578,500 respectively describe liquid sulfur dioxide or a solution of sulfur dioxide and a cosolvent to perform this dual function in a non-aqueous electrochemical cell. Although each of these solutions performs a dual function, their use is not without a few disadvantages. Sulfur dioxide always exists as a gas at room temperature, but in the battery it must be contained as a liquid under pressure or dissolved in a liquid solvent. If sulfur dioxide is used alone, handling and packaging problems arise, and if sulfur dioxide is dissolved in a liquid solvent, other ingredients and combination steps are required.
As mentioned above, a long liquid range extending over the room temperature range is a desirable characteristic for electrolyte solvents.
Clearly, sulfur dioxide is a failure in this regard at atmospheric pressure.

U.S. patent application Ser. discloses a non-aqueous electrochemical cell comprised of a liquid oxyhalide of an element from a group or groups of the periodic table. Oxyhalides can be used as a component of the cathode/electrolyte with active metal anodes, such as lithium anodes, to form excellent high energy density batteries, but if the batteries are stored for long periods of time, about three days or more, Passivation of the anode then appears to result in undesirable voltage lag and high cell impedance during early discharge.

U.S. Pat. No. 3,993,501 minimizes undesirable voltage lag during early discharge in non-aqueous cells using oxyhalide-containing cathodes/electrolytes by providing a vinyl polymer film on the anode surface in contact with the cathode/electrolyte. Discloses methods for preventing or preventing Add this document as a reference.

U.S. patent application Ser. In order to virtually eliminate the initial voltage lag of the battery,
Non-aqueous cells are disclosed that include elemental sulfur or sulfur compounds in the cathode/electrolyte. This disclosure is incorporated herein by reference.

One of the objects of the present invention is to substantially prevent passivation of active metal anodes in liquid cathode/electrolyte cells.

Another object of the present invention is to provide a liquid cathode/electrolyte cell having a vinyl polymer dissolved in the liquid/cathode/electrolyte to substantially prevent passivation of the active metal anode during cell storage.

Another object of the present invention is to use vinyl polymers in combination with vinyl polymers to effectively prevent passivation of active metal anodes during battery storage and use.
The present invention provides an oxyhalide cathode/electrolyte cell system using elemental sulfur or sulfur compounds in the cathode/electrolyte as described in the present invention.

In the following, these and other objects will be explained in more detail.

The present invention provides an ionically conductive cathode/electrolyte comprising an active metal anode, a cathode collector, and a solute dissolved in an active liquid cathode (depolarizer) with or without a reactive or non-reactive co-solvent. The present invention relates to a high energy density non-aqueous battery containing a vinyl polymer dissolved in the battery cathode electrolyte to reduce the time of voltage lag of the battery during discharge. The vinyl polymer concentration dissolved in the cathode/electrolyte is within the range of about 0.25 g to about 4.0 g/liter cathode/electrolyte. Preferably this concentration is between 0.25 and 1.5
g/, most preferably about 0.5 g/. A concentration of 0.25 g/or less is ineffective in reducing the voltage lag time at the initial discharge even to some extent, whereas a concentration of about 4.0 g/or higher is effective in further shortening the voltage lag time at the initial discharge. Not valid.

Vinyl polymer materials suitable for use in accordance with the present invention are selected from the group consisting of homopolymers of vinyl chloride or vinylidene chloride, vinyl esters, dibasic acids, diesters of dibasic acids, and monoesters of dibasic acids. A normally solid vinyl polymer, such as a copolymer containing vinyl chloride or vinylidene chloride, having at least one monomer copolymerized with. The term copolymer is used herein to mean mixed polymers or polymer blends and heteropolymers formed from two or more dissimilar monomers polymerized together (see Concise Chemical Co., Ltd.).・End Technical Dictionary, 3rd edition, H.Bennett
Edited by Chemical Publishing Co., 1974).

Common examples of suitable copolymers include vinyl chloride copolymerized with a vinyl ester such as vinyl acetate: vinyl chloride copolymerized with a diester of a dibasic acid such as dibutyl maleate; Included are combinations of vinyl esters and vinyl chloride copolymerized with maleic acid or dibasic acids, monoesters or diesters of dibasic acids, such as dibutyl maleate or monobutyl maleate. A special example is a vinyl chloride-vinyl acetate copolymer containing 97% vinyl chloride-3% vinyl acetate: a vinyl chloride-vinyl acetate copolymer containing 86% vinyl chloride-14% vinyl acetate: 86% vinyl chloride-13 % vinyl acetate-1% maleic acid.

Vinyl polymer materials suitable for use in the present invention are also disclosed in US Pat. No. 4,141,870, which is incorporated herein by reference.

Also herein referred to as “Journal of
Chemical Education”, Volume 49, 587~
As described in the paper entitled "Electrochemical Reactions in Batteries" by Akiya Kozawa and RA Powers, published on page 291, September 1972, the cathode depolarizer is a cathode reactant, so the electrochemical reaction at the cathode is It is a substance that is reduced to The cathode collector is not an active reducing substance, but acts as a current collector + electron conductor to the positive terminal (cathode terminal) of the battery. In other words, the cathode collector is the site of the electrochemical reduction reaction of the active cathode material and the conductor of electrons to the cathode terminal of the cell.

The active liquid reducing cathode material (depolarizer) can be mixed with a non-reactive material, but with a conductive solute that is added to improve the electrical conductivity of the liquid active reducing cathode material, or It can be mixed with reactive solutes as well as reactive or non-reactive co-solvent materials. A reactive co-solvent material is a material that is electrochemically active and therefore acts as an active cathode material, whereas a non-reactive co-solvent material is a material that is electrochemically inert and thus acts as an active cathode material. A substance that cannot act as an active cathode material.

If a separator is used in the present invention, the separator is chemically inert;
It must be insoluble in the liquid cathode/electrolyte, and it must be porous to allow the liquid electrolyte to permeate into contact with the cell anode, thereby providing an ionic transport path between the anode and cathode. Separators suitable for use in the present invention are nonwoven or woven glass fiber mats.

Any compatible substantially electrically conductive solid may be used as the cathode collector in the cell of the invention.

It is desirable to have as much surface contact as possible between the cathode/electrolyte and the collector. Therefore,
Preferably, a porous collector is used. This type of collector provides a large area interface to the liquid cathode/electrolyte. The collector can be metal and can have any shape, such as a metal film, screen or pressed powder. Preferably, however, the pressed powder collector should consist at least partially of carbonaceous or other large-area material.

A solute is a single or double salt that produces an ionically conductive solution when dissolved in a solvent. Preferably the solute is a complex of an inorganic or organic Lewis acid and an inorganic ionizable salt. The main requirement is that the salt, whether single or double, be compatible with the solvent used and yield an ionically conductive solution. According to the Lewis or electronic concept of acids and bases, many substances that do not contain active hydrogen can act as acid or electron doublet acceptors. The basic concept is described in the chemical literature (Journal of the Franklin Institute, Volume 226 - July/December 1938, 293
~313 pages, by GN Lewis).

The reaction mechanism for the functioning of these complexes in solvents is described in detail in U.S. Pat. It is said to produce a more stable entity than either component alone.

Representative Lewis acids suitable for use in the present invention include aluminum fluoride, aluminum bromide, aluminum chloride, and antimony pentachloride, zirconium tetrachloride, phosphorous pentachloride, boron fluoride, boron chloride, and boron bromide. including.

Ionizable salts suitable for use with Lewis acids include lithium fluoride, lithium chloride, lithium bromide, lithium sulfide, sodium fluoride, sodium chloride, sodium bromide, potassium fluoride, potassium chloride, and potassium bromide. include.

As is clear to those skilled in the art, the double salt formed by a Lewis acid and an inorganic ionizable salt can be used as such or each of these components can be added separately to a solvent. salts or resulting ions can be formed in situ. An example of such a double salt is one formed by combining aluminum chloride and lithium chloride to yield lithium aluminum tetrachloride.

According to the present invention, the invention comprises an active metal anode, a cathode collector, and a liquid cathode/electrolyte having a vinyl polymer dissolved therein, the cathode/electrolyte comprising at least one of the elements of Group or Groups of the Periodic Table. The solute is dissolved in an active reducing electrolyte solvent, such as an oxyhalide and/or a liquid halide of Group, Group or Group of the Periodic Table, with or without a co-solvent. The active reducing electrolyte solvent serves the dual function of acting as a solvent for the electrolyte salt and as an active cathode (depolarizer) for the cell. The term "cathode/electrolyte" is used herein to refer to a solvent-containing electrolyte that can perform this dual function.

The use of a single component in a battery as the electrolyte solvent as well as the active cathode (depolarizer) is a relatively new development. For some reason, in the past, these two
This is because the two functions were naturally considered to be mutually independent and could not be performed by the same substance. For an electrolyte solvent to function in a battery, it must contact both the anode and cathode (depolarizer) to form a continuous ionic path between the two. It was also generally believed that the active cathode material should never be in direct contact with the anode. Therefore, the two functions described above were intended to be mutually contradictory. However, recently some active cathode materials, such as liquid oxyhalides, do not react significantly chemically with the active anode metal at the interface with the anode metal, so that the anode material can directly contact the anode and the electrolyte carrier. It was discovered that it can act as Although the theory behind the inhibition of such direct chemical reactions is not currently well understood and the inventors do not wish to be limited to the theory of the invention, it is important to note that the inherent high activation energy of the reaction Alternatively, direct chemical reactions may be inhibited by the formation of a thin protective film on the anode surface. This protective film on the anode surface must not be formed so excessively as to significantly increase the anodic polarization effect.

Active reducing liquid cathodes, such as oxyhalides, inhibit direct reaction with active metal anode surfaces sufficiently to act as cathode materials and electrolyte carriers in non-aqueous cells, especially at high temperatures. During cell storage, this liquid cathode forms a surface film on the active metal anode. This surface film consists of a relatively thick layer of crystalline material. This layer of crystalline material causes passivation of the anode, resulting in a voltage lag in the initial discharge of the cell, as well as high cell impedance values in the range of 11 ohms to 15 ohms for standard C-size cells. It seems like something.

The degree of anode passivation can be measured by measuring the time required for the closed circuit voltage of the storage cell to reach its desired voltage level after discharge has begun. If this delay is 20
Above seconds, this anode passivation would be considered excessive for most applications.
For example, what is observed in lithium/oxyhalide battery systems is that after a constant load is applied across the terminals of the battery, the battery voltage immediately drops below the desired discharge and then changes with temperature, layer thickness, and load. It grows at a dependent rate.

The exact composition of this crystalline layer is unknown. The thickness and density of the crystal layer as well as the size and shape of the crystals are
It was observed that it varied with the length of storage period and the temperature during storage. For example, in low-temperature storage, compared to the large growth of the crystal layer in high-temperature storage at about 70℃,
Relatively small growth is observed. Also, oxyhalides such as thionyl chloride or sulfuryl chloride are SO ₂
When placed in a lithium anode cell after being saturated with , a crystalline layer was observed to passivate the lithium by rapidly forming on the lithium surface.

In accordance with the present invention, it has been discovered that anode passivation can be largely prevented by dissolving a vinyl polymer in the liquid anode/electrolyte.

The vinyl polymer must remain stable in the liquid cathode/electrolyte during storage and discharge of the battery without significantly reducing the capacity of the battery, and in many cases the vinyl polymer must remain stable during high rate discharge. It may even increase the battery capacity of the battery. Although the inventors do not wish to be bound by the theory of the invention, one reason why vinyl polymers, such as vinyl chloride polymers, are stable in oxyhalide cathode/electrolyte battery systems, such as in lithium/oxyhalide battery systems, is It seems that it can be explained as follows. One of the accepted mechanisms of vinyl chloride polymer degradation
One is dehydrochlorination. In other words, the mechanism is that one Cl atom and one H atom split to form HCl. This process continues until the electron negativity of the remaining Cl atoms on the polymer is compensated by conjugation energy (ie, double bond formation). The subsequent degradation is claimed to occur via a free radical mechanism as described below.

(· indicates a free radical) Most of the compounds observed to interact or interfere with polymer degradation are R

Claims (1)

[Scope of Claims] 1. An ionically conductive cathode-electrolyte solution comprising an active metal anode, a cathode collector, and an ionically conductive cathode-electrolyte solution comprising a solute dissolved in an active liquid cathode; Aqueous battery. 2 Vinyl polymer is a homopolymer of vinyl chloride or vinylidene chloride, vinyl ester,
A copolymer containing vinyl chloride or vinylidene chloride having at least one monomer copolymerized therein selected from the group consisting of dibasic acids, diesters of dibasic acids, and monoesters of dibasic acids; The non-aqueous battery according to claim 1, which is selected from the group consisting of: 3. The non-aqueous battery according to claim 1, wherein the vinyl polymer is selected from the group consisting of vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-dibasic acid copolymer, and vinyl chloride homopolymer. 4. A non-aqueous battery according to claim 1, 2 or 3, wherein the concentration of vinyl polymer in the cathode-electrolyte ranges from about 0.25 to 4.0 grams per electrolyte. 5. A non-aqueous battery according to claim 1, 2 or 3, wherein the concentration of vinyl polymer in the cathode-electrolyte ranges from about 0.5 to 1.5 grams per electrolyte. 6. A non-aqueous battery according to claim 1, 2 or 3, wherein the cathode-electrolyte contains a material selected from the group consisting of lithium sulfide, sulfur monochloride and mixtures thereof. 7 Claim in which the cathode-electrolyte contains at least one liquid oxyhalide selected from the group consisting of thionyl chloride, sulfuryl chloride, phosphorous oxychloride, thionyl bromide, chromyl chloride, vanadyl tribromide, and selenium oxychloride. range 1st, 2nd
Or the non-aqueous battery according to item 3. 8. The nonaqueous battery of claim 7, wherein the at least one liquid oxyhalide is selected from the group consisting of thionyl chloride and sulfuryl chloride. 9. The non-aqueous battery according to claim 1, 2 or 3, wherein the anode is selected from the group consisting of lithium, sodium, calcium, potassium and aluminum. 10. The non-aqueous battery of claim 7, wherein the cathode-electrolyte is an inorganic co-solvent. 11. The non-aqueous battery of claim 7, wherein the cathode-electrolyte is an organic co-solvent. 12. The non-aqueous battery according to claim 7, wherein the anode is lithium and the liquid oxyhalide is thionyl chloride. 13 Claim 7: The anode is lithium and the liquid oxyhalide is sulfuryl chloride.
Non-aqueous batteries as described in section. 14. The non-aqueous battery according to claim 1, 2 or 3, wherein the solute is a complex salt of a Lewis acid and an inorganic ionizable salt.