KR810000365B1 - Non-aqueous cell utilizing liquid organic electrolyte - Google Patents

Abstract

A non-aqueous cell is made up of a highly active metal anode, such as lithium, a solid cathode selected from the group consisting of FeS2, CO3O4, V2O5, Pb3O4, In2S3 and CoS2, and a liquid organic electrolyte consisting of 3-methyl-2-oxazolidone in combination with a low viscosity cosolvent, such as dioxolane, and a metal salt selected from the group consisting of MSCN, MCF3SO3, MBF4, MCIO4 and MM'F6 wherein M is lithium, sodium or potassium and M' is phosphorus, arsenic or antimony.

Description

Non-aqueous battery using liquid organic electrolyte

The present invention provides a highly active metal anode, a solid cathode selected from the group consisting of FeS ₂ , Co ₃ O ₄ , V ₂ O ₅ , Pb ₃ O ₄ , In ₂ S ₃ , CoS ₂ , and a low viscosity cosolvent and A non-aqueous cell using a liquid organic electrolyte based on 3-methyl-2-oxazolidone in combination with selected solutes.

The development of high energy cell systems requires that electrolytes with desirable electrochemical properties, etc., be harmonized with highly reactive positive electrode materials such as lithium, sodium, etc., and efficient use of high energy density negative electrode materials such as FeS ₂ . do. The use of aqueous electrolytes is excluded in these systems because the anode materials are sufficiently active to react chemically with water.

Therefore, it was necessary to focus on the study of non-aqueous electrolyte systems, especially non-aqueous organic electrolyte systems, in order to realize the high energy density obtained by using these highly reactive anodes and high energy density cathodes.

The term " non-aqueous organic electrolyte " refers to an electrolyte in which a solute, which is a salt or double salt of elements I-A, II-A or III-A of the periodic table, is dissolved in a suitable non-aqueous organic solvent. Say.

Conventional solvents include propylene carbonate, ethylene tanol salt or γ-butyrol lactone. The periodic table used here refers to the periodic table of elements and those listed on the back cover of the Handbook of Chemistry and Physics, 48th Edition The Chemistry Rubber Co., Cleveland Ohio 1967-1968. Although many solutes are known and recommended for use, the choice of a suitable solvent is particularly difficult, as many of these solvents used to prepare electrolytes with sufficient electrical conductivity to allow effective ion transport through the solution are described above. It reacts with highly reactive anodes. Most researchers in this field concentrate their research on aliphatic and aromatic nitrogen- and oxygen-containing compounds with some interest in organic sulfur-, phosphorus-, and arsenic-containing compounds in finding suitable solvents. It was.

These findings were extremely unsatisfactory because many of the solvents studied could still not be used effectively with cathode materials with extremely high energy densities, and they would also be corrosive enough to the lithium anode to interfere with their efficient performance over a period of time. Because it was.

US Patent No. 3,547,703 to Blomgren et al. Describes the use of a non-aqueous battery electrolyte employing a solute dissolved in ethylene glycol sulfite.

At the International Conference on Third Non-Aqueous Solvents, held July 5-7, 1972 at Michigan State University, the abstract by HLHoffman, Jr and PGSears showed that 3-methyl-2-oxazolidone was synthesized and It is described that it is easy to purify and has been found to be a good non-aqueous solvent because of its stability, pronounced physical properties, extensive solubility and control.

This document is mainly concerned with the description that 3-methyl-2-oxazolidone has qualified as an excellent potential non-aqueous solvent due to its basic physical and chemical properties.

In a related invention, filed April 22, 1974, filed by the same applicant, U.S. Patent No. 3,871,916 discloses a highly active metal anode, a solid (CFx) n anode, and a low viscosity cosolvent and a combination of A nonaqueous cell using a liquid organic electrolyte based on -methyl-2-oxazolidone has been described.

US Patent No. 3,769,092 by V.L.Dechenaux,

Non-aqueous cell systems are described in B.H. Garth 3,778,310, in which copper oxide electrodes have been used in combination with certain organic electrolytes and highly active anodes.

Theoretical energy, ie the electrical energy that can be obtained potentiometrically from the selective anode-cathode couple, is relatively easy to calculate, but the ratio to the couple that allows the actual energy generated by the assembled cell to access the theoretical energy is It is necessary to select an aqueous electrolyte.

A common problem is that it is practically impossible to predict in advance how well the non-aqueous electrolyte will work with the chosen couple. Thus, a cell should be considered as a unit with three parts, the positive electrode, the negative electrode, and the electrolyte, and the parts of one cell will be predictably interchanged with the parts of the other cell to produce a cell that can function efficiently. It should be understood that it cannot be.

The object of the present invention is to provide a highly active metal anode, a solid cathode selected from the group consisting of FeS ₂ , CO ₃ O ₄ , V ₂ O ₅ , Pb ₃ O ₄ , In ₂ S ₃ and COS ₂ and essentially low viscosity It is to provide a non-aqueous battery using a liquid organic electrolyte composed of 3-methyl-2-osazolidone combined with a cosolvent and a solute.

Another object of the present invention is to provide an electrolyte solvent system for non-aqueous solid cathode batteries, that is, FeS ₂ , Co ₂ O ₄ , V ₂ O ₅ , Pb ₃ O ₄ , In ₂ S ₃ , CoS ₂ cathode batteries This system consists of 3-methyl-2-oxazolidone combined with at least one low viscosity cosolvent and solute. It is also combined with a highly active metal anode, a cathode selected from the group consisting of FeS ₂ , Co ₂ O ₄ , V ₂ O ₅ , Pb ₃ O ₄ , In ₂ S ₃ , CoS ₂ , low viscosity cosolvent and solute Provided is a non-aqueous battery using a liquid organic electrolyte composed of 3-methyl-2-oxazolidone, wherein the solute is based on a 1 kV / cm 2 drainage up to a 1.0 volt blocking voltage when using a lithium anode battery. Thus, the discharge efficiency is about 50% or more, preferably 75% or more.

The present invention provides a new high energy density non-aqueous battery, which is a highly active metal anode, FeS ₂ , Co ₂ O ₄ , V ₂ O ₅ , Pb ₃ O ₄ , In ₂ S ₃ , CoS And a solid organic cathode selected from the group consisting of ₂ , and essentially a liquid organic electrolyte consisting of 3-methyl-2-oxazolidone combined with at least one low viscosity cosolvent and an electrically conductive solute.

Highly active metal anodes suitable for the present invention include lithium (Li), potassium (K), sodium (Na), calcium (Ca), magnesium (Mg) and alloys thereof. Among these active metals, lithium is optional because, besides being a soft metal, it is a soft metal that can be easily assembled into a cell and has the highest energy to weight ratio among the group of suitable anode metals. to be.

Solid cathodes for use in the present invention may be prepared from each other by any suitable method well known to those skilled in the art of electrical art. For cathode materials with relatively low electrical conductivity, it will be necessary to mix the electrically conductive additives with the materials before they are pressed or molded into the cathode structure. Generally, this type of negative electrode material is mixed with 5-10% by weight of an electrically conductive additive such as carbon black and 2-10% by weight of a resin binder such as polytetrafluoro ethylene powder and then 7-20% by weight of a binder. Compressed into a final treated cathode structure with electrically conductive carbon and binder.

U.S. Patent Nos. 3,639,174, 3,655,585, 3,686,038, 3,778,310 and British Patent No. 1,346,890 are cited as representative references for making solid cathodes suitable for use in the present invention.

Liquid organic 3-methyl-2-oxazolidone material (3Me20x), CH ₂ -CH ₂ -O-CO-N-CH ₃ is an excellent non-aqueous solvent because it has a high dielectric constant, chemical inertness to electronic components, Because of its wide liquid range and low toxicity.

However, as is known, when metal salts are dissolved in liquid 2Me20x for the purpose of improving the electrical conductivity of 3Me20x, they are used as electrolytes for non-aqueous cell applications, except when the viscosity of the solution becomes too high to require very low current drainage. Not effective at Thus, according to the present invention, if 3Me20x is used as an electrolyte for non-aqueous batteries that can operate at high energy density levels, it is necessary to add co-solvents of low viscosity. In particular, it is essential to use solid cathodes as specified above together with highly active metal anodes in order to obtain a high energy density level according to the invention. Thus, the present invention provides a highly active metal anode such as lithium, a solid cathode selected from the group consisting of FeS ₂ , Co ₂ O ₄ , V ₂ O ₅ , Pb ₃ O ₄ , In ₂ S ₃ , CoS ₂ , and at least one The goal is a new high energy density cell with an electrolyte consisting of 3Me20x combined with a low viscosity cosolvent and an electrically conductive solute. The negative electrode efficiency of the present invention is about 50% or more based on the theoretical percent by volume of the negative electrode material useful for a battery operating at 1 milliampere / cm 2 of drainage up to 1.0 volt breaking voltage when using a lithium anode. Will be at least 75%.

Low viscosity cosolvents for use in the present invention include tetrahydrofuran (THF), dioxolane, dimethoxyethane (DME), dimethylisoxazole (DMI), diethylcarbonate (DEC), ethylene glycol sulfite (EGS) , Dioxane, dimethyl sulfite (DMS).

Tetrahydrofuran and dioxolane are good cosolvents because they are compatible with metal salts dissolved in liquids and are chemically inert to battery components.

In particular, the total amount of co-solvent of the correct viscosity added should be between about 20-80% of the total solvent volume (ie, excluding solute), to lower the viscosity to a level suitable for use in the cell.

The electrically conductive solutes (metal salts) for use in the present invention with liquid 3Me20x are MCF ₂ SO ₃ , MSCN, MBF ₄ , MClO ₄ and MM'F ₆ , where M is lithium, sodium or potassium and M 'is Phosphorus, arsenic, or antimony) group.

The addition of solutes is necessary to improve the electrical conductivity of 3Me20x so that 3Me20x can be used as electrolyte in non-aqueous cell applications. So the particular salt chosen should be compatible and inactive with the 3Me20x and the electrodes of the cell.

The amount of solute dissolved in liquid 3Me20x should be sufficient to provide good electrical conductivity, for example at least about 10-4 Ohm-1 cm-1. Generally at least about 0.5M will be sufficient for most battery applications.

The invention for a high energy density cell with an electrolyte based on 3Me20x, a solid cathode selected from the groups listed above, and a positive electrode with a highly active metal will be described in more detail in the following examples.

Example 1

The viscosity of several samples of 3Me20x, with or without an electrically conductive solute or low viscosity cosolvent, was obtained using a Cannon-Flenske viscometer. The data obtained are shown in Table 1, which clearly shows the high viscosity of the 3Me20x solution containing dissolved conductive solutes. The viscosity of the solution was 6.61 centistokes when 1 mole of LiClO ₄ was added to 1 liter of 3Me20x as shown in Sample 2.

In Sample 6, when 1 mole of the same metal salt LiClO ₄ was added to 1 liter of 3Me20x and tetrahydrofuran (THF) of the same part, the viscosity of the solution was found to be only 2.87.

Therefore, it is evident that the viscosity of the solution of 3Me20x and the metal salt can be reduced by the addition of a specially selected low viscosity cosolvent.

(표1)

Table 1

Example 2

Each of the six planar cells was made using a nickel metal substrate, with a shallow depression inside the substrate, where the cell contents were placed, and a nickel metal cap placed above it to seal the cell. The contents of each sample cell consisted of a 1.0 inch diameter lithium disk consisting of five lithium foils with a total thickness of 0.10 inch, about 4 ml of specific electrolyte as shown in Table 3, and 1.0 inch diameter perforated with some electrolyte absorbed. And a non-woven polypropylene separator (0.01 inch thick), and a solid FeS ₂ negative electrode mixture squeezed onto a porous 1.0 inch diameter negative electrode precipitate.

The FeS ₂ electrodes were made of a mixture of FeS ₂ , acetylene black, and polytenerafluoroethylene binder, pressed on both sides of a nickel mesh. FeS ₂ and acetylene black were first finely ground together and then drained of excess liquid, followed by water, ethanol and polytetrafluoro in the ratios shown in Table 2 before press casting (at 18,000 Psi) on a metal carrier or net. And Teflon emulsion, commercially available from DuPnot, designated as ethylene emulsion (T-30-B).

Each completed FeS ₂ electrode contained about 1.9 grams of negative electrode mixture, which was about 1.0 inches in diameter and about 0.04 inches thick.

The total thickness of the positive electrode, negative electrode and negative electrode collector, and separator was measured about 0.15 inches for each cell.

The average discharge voltage and discharge capacity at various current distributions up to 1.0 volt breaking voltage were obtained for each battery and are shown in Table 3.

Since the cells are negative electrode confined, the negative electrode efficiency was calculated as% based on the theoretical capacity of the negative electrode material useful in each cell.

For example, the theoretical efficiency of FeS ₂ as a negative electrode material in a lithium positive electrode battery discharged at 1 milliampere / cm 2 up to 1.0 volt blocking voltage was calculated as follows. Assume the following reaction.

If 1 gram of FeS ₂ is used here, the fraction of equivalent weight is 1 / 29.96. Since one Faraday electricity is obtained from one equivalent weight, the AH per equivalent weight is calculated as follows.

Therefore, 1 / 29.96 equivalent weight x 26.8 AH / equivalent weight = 0.894 AH. This 0.894AH or 894mAH is the theoretical capacity of 1 gram of FeS ₂ material when used as a negative electrode in a lithium anode cell, and by using this value as a reference, the negative electrode of FeS ₂ material when used as a negative electrode in a cell with various electrolytes The efficiency can be calculated.

As evidenced by the experimental data shown in Table 3, the cathode efficiencies of the cells ranged from 69.0% -89.7%, thus demonstrating that an efficient and high energy density FeS ₂ non-aqueous cell rate can be produced by using the present invention. .

Example 3

Three planar cells were prepared as described in Example 2, only the solid cathode was C0 ₄ made as described in Example 2 for FeS ₂ using the ratios shown in Table 4 and adopted in each cell. The electrolyte is as shown in Table 5, with the exception.

The average discharge voltage and discharge capacity at various currents up to 1.0 volt breaking voltage were obtained for each battery and are shown in Table 5.

As in the previous examples, the cells are negative electrode constrained, whereby the theoretical efficiency of CO ₃ O ₄ as negative electrode depletion in a lithium battery discharging at a drain of 1 milliampere / cm 2 up to 1.0 volt blocking voltage is calculated as follows: . Assume the following reaction.

If 1 gram of Co ₃ O ₄ is used here, the fraction of equivalent weight is 1 / 30.1. Since Faraday's electricity is 26.8AH / equivalent weight, it is 1 / 30.1 equivalent weight × AH / equivalent weight = 0.890AH.

This 0.890AH or 890mAH is the theoretical capacity of 1 gram of Co ₃ O ₄ material when used as a negative electrode in a lithium positive cell, and by using this value as a standard value C0 ₃ O when used as a negative electrode in a battery with a variety of electrolytes ₄ Cathode efficiency of the material can be calculated.

The experimental data shown in Table 5, in which the negative electrode efficiency of the cell ranges from 71.4% to 80.9%, shows that efficient, high energy density Co ₃ O ₄ non-aqueous cells can be produced by using the present invention.

Example 4

Two flat cells were made as described in Example 2, only the solid anode was V ₂ O ₅ prepared as described in Example 2 for FeS ₂ using the ratios shown in Table 6, each The exception is that the electrolytes employed in the cells are as shown in Table 7.

The average discharge capacity at 0.8 milliampere / cm 2 flow up to 1.0 volt breaking voltage was obtained for each cell and is shown in Table 7.

As in the previous embodiments, the cells are negative-limiting, whereby the theoretical efficiency of V ₂ O ₅ as a negative electrode material in a lithium cell discharged at 1 milliampere / cm 2 drainage up to a cut-off voltage of 1.0 volts is as follows. Calculated as Assume the following reaction.

If 1 gram of V ₂ O ₅ is used here, the equivalent weight fraction is 1 / 45.47. One Faraday's electricity is 26.8AH / equivalent weight, so 1 / 45.47 equivalent weight × 26.8AH / equivalent weight = 0.589AH.

This is a theoretical capacity of 598mAH 0.589AH or V ₂ O ₅ material 1 grams when V ₂ O ₅ positive electrode in a lithium battery is used as a cathode, by using this value as the standard value when used as a cathode in a cell having a number of electrolyte The cathode efficiency of the V ₂ O ₅ material can be calculated.

The experimental data shown in Table 7 in which the negative electrode efficiency of the cell varies between 68.4% and 67.6% indicates that efficient and high energy density V ₂ O ₅ nonaqueous cells can be made by using the present invention.

Example 5

Three flat cells were made as described in Example 2, except the solid cathode was Pb ₃ O ₄ prepared as described in Example 2 for FeS ₂ using the ratios shown in Table 8. The electrolytes employed in each cell are as shown in Table 8.

Average discharge voltages and discharge capacities at various current distributions up to 1.0 volt breaking voltage were obtained for each cell, which is shown in Table 9.

As in the previous embodiment, the cells are limited to the negative electrode, whereby the theoretical efficiency of Pb ₃ O ₄ as the negative electrode material in a lithium battery discharged at 1 milliampere / cm 2 drainage up to a cut-off voltage of 1.0 volts is calculated as follows: do; Assume the following reaction.

If 1 gram of Pb ₃ O ₄ is used, the equivalent weight fraction is 1 / 85.5. 1 Faraday's electricity is 26.8AH / equivalent weight game, which is 1 / 85.7 equivalent weight × 26.8 AH / equivalent weight + = 0.312AH.

This 0.312AH or 312mAH is the theoretical capacity of 1 gram of Pb ₃ O ₄ material when used as a Pb ₃ O ₄ negative electrode in a lithium positive cell, and by using this value as a reference, Pb ₃ O ₄ in a battery with various electrolytes When the material is used as the cathode, the cathode efficiency of the Pb ₃ O ₄ material can be calculated.

The test data shown in Table 9, in which the cathode efficiency of the cell ranges from 72.5% to 99.8%, shows that efficient and high energy density Pb ₃ O ₄ non-aqueous cells can be made by using the present invention.

Example 6

Two flat cells were made as described in Example 2, except the solid cathode was In ₂ S ₃ prepared as described in Example 2 for FeS ₂ using the ratios shown in Table 10. The electrolytes employed in each cell are shown in Table 11.

The average discharge voltage and discharge capacity at 0.2 milliampere / cm 2 up to a 1.0 molar cutoff voltage were obtained for each battery, which is shown in Table 11.

As in the previous example, the cells are negative electrode constrained, whereby the theoretical efficiency of In ₂ S ₂ as the negative electrode material in a lithium battery discharged at 1 milliampere / cm 2 up to a cut-off voltage of 1.0 volt is calculated as follows; Assume the following reaction.

If 1 gram of In ₂ S ₂ is used,

The fraction of equivalent weight is 1 / 54.27. Faraday's electricity is 26.8AH / equivalent weight, so 1 / 54.27 equivalent weight × 26.8AH / equivalent weight = 0.494AH.

This is a theoretical capacity of 494mAH 0.494AH or In ₂ S ₃ when the material 1 grams In ₂ S ₃ is used as the negative electrode in a lithium anode cell, the use of this value to a reference value, the battery with a number of electrolytes In ₂ S The cathode efficiency of In ₂ S ₃ material can be calculated when ₃ material is used as cathode.

The test data shown in Table 11, in which the negative electrode efficiency of the cell ranges from 59% to 95%, shows that by using the present invention, an efficient and high energy density In ₂ S ₃ non-aqueous cell can be produced.

Example 7

Four flat cells were made as described in Example 2, except for CoS _2, prepared as described in Example 2 using the ratios shown in Table 12 instead of solid cathode FeS ₂ , each cell. The electrolytes employed in are shown in Table 13.

The average discharge voltage and discharge capacity for a medium of 0.2 or 0.8 milliamps / cm 2 up to a 1.0 volt breaking voltage were obtained for each cell, which is shown in Table 13.

As in the previous embodiments, the cells are negative electrode constrained, whereby the theoretical efficiency of CoS ₂ as a negative electrode material in a lithium battery discharged at 1 milliampere / cm 2 drainage up to a cut-off voltage of 1.0 volts is calculated as follows.

Assume the following reactions:

If 1 gram of CoS ₂ is used, the equivalent weight fraction is 1 / 30.73. One Faraday's electricity is 26.8AH / equivalent weight game, which is 1 / 30.73 equivalent weight × 26.8AH / equivalent weight = 0.872AH.

These 0.872AH or 872mAH when CoS ₂ when used as a cathode in a lithium battery and the positive electrode theoretical capacity of the CoS ₂ material 1g, by using the basis of this value, the battery with a number of electrolytes are used as the negative electrode CoS ₂ CoS ₂ The cathode efficiency of the material can be calculated.

The test data shown in Table 13, in which the negative electrode efficiency of the cell varies between 86.8% and 93.5%, indicates that efficient and high energy density CoS ₂ non-aqueous cells can be produced by using the present invention.

Claims (1)

As detailed herein, at least one low viscosity solvent selected from the group consisting of tetrahydrofuran, dioxolane, dimethyl isoxazole, diethyl carbonate, ethylene glycon sulfite, dioxane and dimethyl sulfite, and M ₃ -methyl-2- bound with an electrically conductive solute selected from the group consisting of lithium, sodium or potassium and M 'is phosphorus, arsenic or antimony, MCF ₃ SO ₃ , MSCN, MBF ₄ , MClo ₄ and MM'F ₆ Liquid organic electrolyte composed of oxazolidone: solid cathode selected from the group consisting of FeS ₂ , Co ₃ O ₄ , V ₂ O ₅ , Pb ₃ O ₄ , In ₂ S ₃ and CoS ₂ : lithium, potassium, sodium, calcium, A nonaqueous battery characterized by consisting of a highly sulfur metal anode selected from the group consisting of magnesium and their alloys.