JPH01146260A - Inorganic nonaqueous electrolyte battery - Google Patents

Abstract

PURPOSE:To prevent voltage drop in the initial stage of discharge, especially large voltage drop, which instantaneously appears immediately after the start of discharge, even in the large current discharge of a battery after storage by adding the polymer of an oxygen-containing organic silane compound to an electrolyte. CONSTITUTION:The polymer of an oxygen-containing organic silane compound is added to an electrolyte. This silane compound polymer is taken-in on the surface of a lithium electrode, and a lithium chloride film formed is made coarse. Lithium in the negative electrode is easily converted into lithium ion even in the large current discharge of a battery stored at high temperature or for a long time. The diffusion of lithium ions from the negative electrode to the electrolyte is smoothly conducted without any obstruction by the lithium chloride film. Hence, activation polarization and concentration polarization are decreased and the voltage drop in the initial stage of discharge is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an inorganic non-aqueous electrolyte battery in which an oxyhalide is used as a positive electrode active material and an electrolyte solvent, and an alkali metal is used as a negative electrode active material.

[Conventional technology]

Oxyhalides such as thionyl chloride, sulfuryl chloride, and phosphoryl chloride, as typified by thionyl chloride-lithium batteries, are used as the positive electrode active material and the solvent for the electrolyte, and alkali metals such as lithium, sodium, and potassium are used as the negative electrode active material. In an inorganic non-aqueous electrolyte battery, using the thionyl chloride-lithium battery, which is a typical battery, as an example, thionyl chloride, which is the positive electrode active material, is in direct contact with the lithium negative electrode, so chloride is deposited on the lithium negative electrode. A coating of lithium is formed. This lithium chloride film is a sparse film when it is initially formed, but when stored at high temperatures or for a long period of time, it grows into a dense film, leading to passivation of the lithium negative electrode.

As a result, if this battery is used after being stored at high temperatures or for a long period of time, a voltage drop will occur at the beginning of discharge and the desired voltage will not be reached, resulting in the problem that equipment using this battery as a drive power source will not be able to operate. . In particular, the whisker-like voltage drop that appears instantaneously between several 100 μs and several ms immediately after the start of discharge (see the discharge characteristics of Comparative Example 1 in Figure 2) is large, and as a result, the range of use of the battery is extremely limited. become. This phenomenon of voltage drop at the beginning of discharge becomes more noticeable as the current increases, and this phenomenon occurs not only when an undischarged battery is stored, but also when the battery is stored after being used for a certain amount of time. It has the peculiarity of appearing repeatedly in each storage.

Therefore, as shown in Japanese Patent Laid-Open No. 60-249253, chlorinated polyethylene has been added to the electrolytic solution to suppress the voltage drop at the initial stage of discharge, and
As shown in Japanese Patent No. 1-190863, it has been proposed to add polyethylene oxide to the electrolytic solution to suppress the voltage drop at the initial stage of discharge.

However, even when chlorinated polyethylene or polyethylene oxide is added to the electrolytic solution as described above, there is almost no suppression of the whisker-like large voltage drop that appears instantaneously between several 100 μs and several ms immediately after the start of discharge. It showed no effect.

[Problems to be Solved by the Invention] The present invention solves the problem that the conventional products mentioned above have, in which a voltage drop occurs at the beginning of discharge due to discharge after high temperature or long-term storage. It is an object of the present invention to provide an inorganic non-aqueous electrolyte battery that does not cause a voltage drop in the initial stage of discharge even during large current discharge after storage.

[Means for solving problems]

By adding a polymerized oxygen-containing organic silane compound to the electrolytic solution, the present invention is capable of producing voltage drops that appear instantaneously at the beginning of discharge, especially immediately after the start of discharge, even during high-current discharge after high-temperature or long-term storage. This is to prevent a large voltage drop from occurring.

That is, by adding a polymerized oxygen-containing organic silane compound to the electrolytic solution, the polymerized oxygen-containing organic silane compound is incorporated into the surface of the lithium negative electrode, and the formed lithium chloride film becomes a very rough film. Then,
Even during high-temperature or high-current discharge after long-term storage, the lithium in the negative electrode easily turns into lithium ions, and the diffusion of lithium ions from the negative electrode into the electrolyte takes place smoothly without being inhibited by the lithium chloride coating. In this way, activation polarization and concentration polarization become small, and a voltage drop at the initial stage of discharge is prevented.

The reason why the film formed on the lithium negative electrode becomes rough when the polymerized oxygen-containing organosilane compound is added to the electrolyte as described above is not necessarily clear at present, but The oxygen bond in the polymerized oxygen-containing organic silane compound is reactive with lithium, and when this oxygen bond is broken by lithium, the lithium on the surface of the negative electrode and the polymerized organic silane compound are directly bonded. However, it is thought that polymerized organic silane compounds are scattered on the negative electrode lithium surface, making the lithium chloride coating rough. In addition, as mentioned above, polymerized organic silane compounds are directly bonded and scattered on the surface of the negative electrode lithium, making the lithium chloride film rough, which suppresses the increase in the interfacial resistance of the negative electrode lithium. Become.

In particular, when this polymerized oxygen-containing organic silane compound is added to the electrolyte, it is possible to prevent the large voltage drop that appears instantaneously immediately after the start of discharge when a battery is discharged after being stored at high temperatures or for a long period of time. This remarkable effect not seen with other additives is produced, and this is thought to be due to the direct bonding of the polymerized organic silane compound with the lithium on the surface of the negative electrode as described above.

In the present invention, the polymerized oxygen-containing organosilane compound to be added to the electrolytic solution is, for example, the following formula (H
In addition to the polydimethylsiloxane ethylene oxide represented by the above, compounds represented by the formulas (n), (l[), (IV), and (V) can be mentioned.

Formula (I) Formula (■) Formula (■): Formula (■): Formula (■): The polymerized oxygen-containing organic silane compound represented by the above formula (n) is generally a polyether-modified silicone oil. An example of a commercially available product is silicone oil KF353 from Shin-Etsu Chemical Co., Ltd.
Examples include those commercially available under the trade name (A).

Further, the polymerized oxygen-containing organic silane compound represented by the above formula (I[l) is generally called epoxy-modified silicone oil, and an example of a commercially available product thereof is:
For example, silicone oil KF1 from Shin-Etsu Chemical Co., Ltd.
One example is one commercially available under the trade name 00T.

The polymerized oxygen-containing organic silane compound represented by formula (IV) is called carboxyl-modified silicone oil in -i, and examples of its commercially available products include silicone oil from Shin-Etsu Chemical Co., Ltd. X-22-3
One example is one commercially available under the trade name 7018.

The polymerized oxygen-containing organic silane compound represented by the formula (V) is called a radical-reactive silicone oil in -M, and an example of a commercially available product is silicone oil from Shin-Etsu Chemical Co., Ltd. Oil X-22-500
Examples include those commercially available under the trade name 2.

The polymerized oxygen-containing organic silane compounds represented by the above formulas (1) to (TV) have a molecular weight of 50
0 to 3,000 is preferred.

The amount of these polymerized oxygen-containing organic silane compounds added to the electrolytic solution is preferably in the range of 0.1 g/l to 10 g/l. In other words, if the amount of the polymerized oxygen-containing organosilane compound added to the electrolyte solution is less than the above range, the effect of roughening the lithium chloride film formed on the negative electrode surface will not be sufficiently exhibited, and the polymerization Even if the amount of the oxygen-containing organic silane compound added to the electrolytic solution is larger than the above range, the effect of roughening the lithium chloride film and preventing voltage drop at the beginning of discharge does not change much. This is because as the amount of the organic silane compound added increases, the amount of positive electrode active material that can be filled into the battery decreases, which is not preferable.

In the battery of the present invention, an oxyhalide that is liquid at room temperature, such as thionyl chloride, phosphoryl chloride, or sulfuryl chloride, is used as the positive electrode active material. These oxyhalides are used as positive electrode active materials and as solvents for the electrolyte, and the electrolyte contains these oxyhalides as well as LiAICL, LiAIBra, and LiGaC.
1a, LiB,. It is prepared by dissolving a supporting electrolyte such as C1, . In preparing the electrolytic solution, supporting electrolytes such as LiCl and AlC11 are added to oxyhalides so that they exist in the electrolytic solution in the form of LiAICIa (however, they are not ionized). Alternatively, a polymerized oxygen-containing organosilane compound may be added together with the supporting electrolyte when preparing the electrolyte, or it may be added before the supporting electrolyte. Good too.

As the negative electrode active material, for example, alkali metals such as lithium, sodium, and potassium are used.

〔Example〕

Next, the present invention will be explained in more detail by giving examples.

Example 1 A AA-sized thionyl chloride-lithium type inorganic non-aqueous electrolyte battery was produced using thionyl chloride as a positive electrode active material and lithium as a negative electrode active material.

The electrolyte contains the above thionyl chloride and Li as a supporting electrolyte.
AlCl4 (However, when adding to thionyl chloride, Li
C1 and AlC1) is added to 1.2-o1/j! In this example, 2 g/l of polydimethylsiloxane ethylene oxide (manufactured by General Science Corporation) is dissolved in this electrolytic solution.

FIG. 1 shows the above-mentioned battery. In the figure, 1 is a negative electrode made of lithium, and this negative electrode 1 is formed by pressing a lithium sheet onto the inner peripheral surface of a cylindrical battery container 2 with a bottom. ing. 3 is a positive electrode, and this positive electrode 3 is made of a cylindrical porous carbon molded body containing acetylene black as a main component, and does not react itself, but has a current collecting effect and reacts with thionyl chloride and lithium ions. It acts as a catalyst. 4 is an electrolytic solution, and this electrolytic solution 4 is obtained by dissolving Li A I CI a in thionyl chloride as described above, and in this example, polydimethylsiloxane ethylene oxide is dissolved in this electrolytic solution 4. g/l added, and 3.9 mj in the battery! Injected. In this battery, thionyl chloride is not only the solvent of the electrolytic solution as described above, but also the positive electrode active material. Reference numeral 5 denotes a separator made of glass fiber nonwoven fabric, which has a cylindrical shape and separates the cylindrical negative electrode 1 and the cylindrical positive electrode 3. 6 is a positive electrode current collector, which is made of a stainless steel rod.

Reference numeral 7 denotes a battery lid, and this battery lid 7 is made of stainless steel, and its raised outer peripheral portion is joined to the open end of the battery container 2 by welding.

A glass layer 8 is provided on the inner circumferential side of the battery cover 7 between the positive electrode terminal 9 and the glass layer 8 insulating the battery cover 7 and the positive electrode terminal 9. The constituent glass is fused to the inner circumferential surface of the battery lid 7, and the constituent glass is fused to the outer circumferential surface of the positive terminal 9 on the inner circumferential surface, sealing between the battery M7 and the positive terminal 9. The opening is sealed with a so-called hermetic seal. Positive terminal 9
is made of stainless steel and has a pipe shape when assembling the battery.
It is used as an electrolyte inlet, and its upper end is sealed by welding to the upper part of the positive electrode current collector 6 inserted into the hollow part after the electrolyte is injected. Reference numerals 10 and 11 are a bottom isolation member and an upper isolation member respectively made of glass fiber nonwoven fabric, and 12 is an air chamber provided at the upper part of the battery.

Example 2 Silicone oil KF353 (A) from Shin-Etsu Chemical Co., Ltd. was used instead of polydimethylsiloxane ethylene oxide
) (trade name, polymerized oxygen-containing organic silane compound represented by the above formula (II)) was used as an electrolytic solution containing 2 g/l of thionyl chloride-lithium chloride having the same composition as in Example 1. An inorganic non-aqueous electrolyte battery was fabricated.

Example 3 Electrolysis in which 2 g/l of silicone oil KF100T (trade name, polymerized oxygen-containing organic silane compound represented by the above formula (III)) from Shin-Etsu Chemical Co., Ltd. was added in place of polydimethylsiloxane ethylene oxide. An inorganic nonaqueous electrolyte battery of thionyl chloride-lithium chloride having the same structure as in Example 1 except that the liquid was used was produced.

Example 4 Silicone oil X-22-370 from Shin-Etsu Chemical Co., Ltd. was used instead of polydimethylsiloxane ethylene oxide.
1E (trade name, polymerized oxygen-containing organic silane compound represented by the above formula (N'')) was used as an electrolytic solution containing 2 g/2 of the same composition as in Example 1, except that lithium thionyl chloride was used. We fabricated an inorganic non-aqueous electrolyte battery based on this method.

Example 5 Silicone oil X-22-500 from Shin-Etsu Chemical Co., Ltd. was used instead of polydimethylsiloxane ethylene oxide.
A thionyl chloride-lithium chloride system having the same structure as in Example 1 except that an electrolytic solution containing 2 g/2 of 2 (trade name, polymerized oxygen-containing organic silane compound represented by the above formula (V)) was used. An inorganic non-aqueous electrolyte battery was fabricated.

Comparative Example 1 An electrolytic solution containing no polymerized oxygen-containing organosilane compound such as polydimethylsiloxane ethylene oxide, that is, thionyl chloride containing LiAlC1,
1.2 mol/I! ? A thionyl chloride-lithium inorganic non-aqueous electrolyte battery was produced having the same structure as in Example 1 except that only the dissolved electrolyte solution was used.

Comparative Example 2 A thionyl chloride-lithium inorganic non-aqueous electrolyte battery having the same structure as Example 1 except that an electrolyte containing 2 g/l of chlorinated polyethylene instead of polydimethylsiloxane ethylene oxide was used. Created.

Comparative Example 3 A thionyl chloride-lithium-based inorganic non-aqueous electrolyte battery having the same structure as Example 1 except that an electrolyte containing 0.2 g/l of polyethylene oxide was used instead of polydimethylsiloxane ethylene oxide. was created.

The batteries of Examples 1 to 5 and Comparative Examples 1 to 3 above were heated at 60°C.
After storage for 20 days at 20° C., the lowest voltage when discharged at 10Ω for 10ms was measured. That is, the extent of the voltage drop that appears immediately after the start of discharge during high-current (corresponding to about 200 mA at a load of 10 Ω) discharge after high-temperature storage was investigated. The results are shown in Table 1.

In Table 1, the polymerized oxygen-containing organic silane compounds used in Examples 2 to 5 are indicated by trade name.

As shown in Table 1, after storage at 60"C for 20 days, 1
When the battery of Comparative Example 1 to which no additives were added had a voltage of 10m s R11 at 0Ω, the minimum voltage decreased to 1.189 V, and a large voltage drop was observed, whereas in the battery of Example 1, the lowest voltage decreased to 1.189 V. For batteries 1 to 5, the minimum voltage is 2.050V, although there are slight differences depending on the additives.
~2.109 V, and no significant voltage drop was observed. In addition, the battery of Comparative Example 2 in which chlorinated polyethylene was added to the electrolyte and the battery in Comparative Example 3 in which polyethylene oxide was added to the electrolyte had a minimum voltage of 1.
．． 203V and 1.200V, which are close to those of the battery of Comparative Example 1, and in such a large current discharge, there was hardly any effect of preventing the voltage drop that appears immediately after the start of discharge.

Figure 2 shows the battery of Example 1 and the battery of Comparative Example 1 at 20 degrees.
This is a diagram showing the discharge characteristics when discharging at a constant resistance of 10Ω at C, the horizontal axis shows the discharge time, and the vertical axis shows the discharge voltage.

As shown in Figure 2, in the battery of Comparative Example 1 to which no additives were added, a large voltage drop with a 1mSmS drop was observed after the start of discharge, but in the battery of Example 1, such a large voltage drop was observed. No whisker-like voltage drop was observed.

The batteries of Examples 2 to 5 were also discharged under the same conditions as above to examine their discharge characteristics.
The battery also had the same discharge characteristics as the battery of Example 1, with no whisker-like voltage drop immediately after the start of discharge.

〔Effect of the invention〕

As explained above, in the present invention, by adding a polymerized oxygen-containing organic silane compound to the electrolytic solution,
Even during large current discharge after storage, it was possible to prevent a voltage drop at the initial stage of discharge, especially a large voltage drop that appears instantaneously immediately after the start of discharge.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of an inorganic non-aqueous electrolyte battery of the present invention. FIG. 2 is a discharge characteristic diagram of the battery of Example 1 and the battery of Comparative Example 1. DESCRIPTION OF SYMBOLS 1...Negative electrode, 3...Positive electrode, 4...Electrolyte solution No. 1 Fig. 2 Fig. □Example 1 1111 Comparative Example 1 Discharge time (ms)

Claims (2)

[Claims] (1) In an inorganic non-aqueous electrolyte battery that uses an oxyhalide as a positive electrode active material and an electrolyte solvent and an alkali metal as a negative electrode active material, the addition of a polymerized oxygen-containing organic silane compound to the electrolyte Characteristics of inorganic non-aqueous electrolyte batteries. (2) The inorganic nonaqueous electrolyte according to claim 1, wherein the polymerized oxygen-containing organic silane compound is at least one compound selected from the following formulas (I) to (V): battery. Formula (I): ▲There are mathematical formulas, chemical formulas, tables, etc.▼ Formula (II): ▲There are mathematical formulas, chemical formulas, tables, etc.▼ Formula (III): ▲There are mathematical formulas, chemical formulas, tables, etc.▼ Formula (IV): ▲There are mathematical formulas, chemical formulas, tables, etc.▼ Formula (V): ▲There are mathematical formulas, chemical formulas, tables, etc.▼