JP2006286501A - Nonaqueous electrolyte battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte battery suppressing increase in internal resistance even when the nonaqueous electrolyte battery is used or stored for a long time, and at the sane time suppressing the generation of leakage, and enhancing reliability especially even when manganese dioxide is used in a positive electrode. <P>SOLUTION: The nonaqueous electrolyte battery is equipped with the positive electrode, a negative electrode mainly comprising lithium metal or a lithium alloy, and a nonaqueous electrolyte, and the positive electrode is mainly comprised of manganese dioxide, and a compound containing anions comprising a saccharin group or its derivative is added to the nonaqueous electrolyte. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is a non-aqueous electrolyte battery using manganese dioxide as a positive electrode and lithium metal or a lithium alloy as a negative electrode. Specifically, a compound that suppresses an increase in internal resistance is added to the non-aqueous electrolyte, and the battery The present invention relates to a non-aqueous electrolyte battery with improved storage characteristics.

  Non-aqueous electrolyte batteries have high energy density and excellent long-term reliability, so they are used as memory backup for electronic equipment, as power sources for cameras, small equipment, various measuring equipment, and control equipment. Etc. are used in a wide range of fields. In this type of battery, a configuration in which a light metal such as lithium is used for the negative electrode and graphite fluoride or manganese dioxide is used for the positive electrode is common. In particular, a battery using manganese dioxide for the positive electrode has excellent discharge characteristics under a high load even in a low temperature environment, and is mainly used for a power source of a camera and a power source of a small portable device.

As the solvent constituting the non-aqueous electrolyte of these batteries, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, sulfolane, dimethoxyethane, tetrahydrofuran, dioxolane, γ-butyrolactone, etc. are used alone or as a mixture. The solutes include LiClO ₄ , LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ) or the like is generally used, and these solutes are dissolved in the solvents mentioned above.
Further, the non-aqueous electrolyte described above has a case of adding a compound other than the above-mentioned solute as an additive for the purpose of improving battery characteristics such as discharge characteristics and life characteristics. For example, a configuration is known in which an additive is added to a non-aqueous electrolyte for the purpose of improving storage characteristics and suppressing internal resistance. In these configurations, the additive contained in the non-aqueous electrolyte suppresses an increase in internal resistance by forming a film on the surface of the negative electrode using lithium metal (or an alloy thereof). Although the specific action and mechanism that the film gives to the suppression of the increase in internal resistance is not clear, the film suppresses the reactivity between the negative electrode surface and the electrolyte, or the film is a negative electrode. It is common to recognize that an increase in internal resistance is suppressed by increasing the ionic conductivity between the surface and the electrolyte.

As an example of adding an additive, Patent Document 1 proposes a configuration in which a carbonate having a specific structural formula is added to an organic cyclic carbonate for the purpose of improving discharge characteristics in a lithium (nonaqueous electrolyte) battery. Yes. This additive made of carbonate forms a desired film on the negative electrode surface by selectively acting with other electrolyte components (solvent and solute). And the said film is excellent in the permeability | transmittance of lithium, and does not inhibit reaction in a negative electrode. In addition, the effect of improving discharge characteristics in a non-aqueous electrolyte battery by suppressing the formation of a coating film having poor lithium permeability due to the reaction between the electrolyte component or the impurity component contained in the electrolyte solution and the negative electrode It plays.
JP 2003-089332 A

As described above, the additive added to the non-aqueous electrolyte contributes to the improvement of the battery characteristics by forming a film on the negative electrode surface. Furthermore, moisture remaining inside the battery reacts with the negative electrode to effectively suppress the deterioration of the discharge characteristics, and the effect of improving the discharge characteristics by the coating is extremely large. However, when the battery is in a usage environment where it is stored or used for a long period of time, especially when the battery is used at a high temperature and used or stored for a long period of time, non-aqueous electrolysis There is a phenomenon in which a reaction between the liquid and the positive electrode or a reaction with moisture remaining in the battery is caused to increase the internal resistance.

  In addition, in a battery using manganese dioxide for the positive electrode, the reactivity between manganese dioxide of the positive electrode and the non-aqueous electrolyte is high, and a reaction accompanied by decomposition of the non-aqueous electrolyte tends to occur. Decomposition products generated by this reaction are likely to be deposited on the surface of the positive electrode, causing an increase in internal resistance, resulting in a voltage drop during discharge. In addition, the reaction involving decomposition of manganese dioxide and the non-aqueous electrolyte also causes an increase in the battery internal pressure, which is a cause of leakage and the like. As described above, the reaction starting from the decomposition of the non-aqueous electrolyte causes problems such as deterioration of discharge characteristics and occurrence of liquid leakage, and decreases the reliability of the non-aqueous electrolyte battery. In particular, equipment premised on long-term storage and use requires high reliability for non-aqueous electrolyte batteries even in a severe environment. The adverse effects of the deterioration of the discharge characteristics and the occurrence of liquid leakage may spread to situations such as data loss and device operation stoppage depending on the usage state of the device, and even the reliability of the device may be shaken.

  The present invention has been made in view of the above-described conventional problems, and suppresses deterioration of discharge characteristics due to an increase in internal resistance even when a nonaqueous electrolyte battery is used and stored for a long period of time. Another object of the present invention is to provide a battery in which the occurrence of liquid leakage is suppressed. It is another object of the present invention to provide a non-aqueous electrolyte battery having high reliability even when manganese dioxide is used for the positive electrode.

  To achieve the above object, the non-aqueous electrolyte battery of the present invention is a non-aqueous electrolyte battery comprising a positive electrode, a negative electrode mainly composed of lithium metal or a lithium alloy, and a non-aqueous electrolyte. Manganese dioxide is the main component, and a compound containing an anion composed of a saccharin group or a derivative thereof is added to the non-aqueous electrolyte.

  The present inventors examined the influence of a compound containing an anion composed of a saccharin group or a derivative thereof added to a non-aqueous electrolyte on a power generation element, particularly a non-aqueous electrolyte and a positive electrode. As a result, it has not been possible to elucidate the causal relationship between the combination of the compound and the power generation element on the improvement of storage characteristics. However, the present inventors have obtained the following knowledge.

  That is, in the non-aqueous electrolyte battery according to the present invention, a compound containing an anion composed of a saccharin group or a derivative thereof added to the non-aqueous electrolyte reacts with manganese dioxide, and the reaction product is a positive electrode (manganese dioxide surface). It is considered that a stable film was formed and this film suppressed the increase in internal resistance. More specifically, this film has a structure close to a saccharin group or a derivative thereof, and this film prevents reaction products accompanying the decomposition of the non-aqueous electrolyte from being deposited on the surface of the positive electrode. It is guessed.

  Furthermore, the reaction between the compound and manganese dioxide occurs in preference to the reaction between the non-aqueous electrolyte and manganese dioxide, thereby substantially preventing the latter reaction (reaction between the non-aqueous electrolyte and manganese dioxide). It seems to be suppressing. Since the coating does not inhibit the movement of lithium into the interior, it can be concluded that lithium is quickly inserted into the manganese dioxide in the discharge reaction and that the coating does not increase the internal resistance. .

  As described above, based on the knowledge of the present inventors, a compound containing an anion composed of a saccharin group or a derivative thereof forms a film on the positive electrode, and since this film exists stably, it can be stored for a long period of time, particularly in electrolysis. Even when stored for a long time in a high-temperature environment where the reaction between the liquid and the positive electrode is likely to occur, the degradation of the electrolytic solution due to the reaction and the increase in internal resistance accompanying the generation and precipitation of the product are suppressed, and the battery is increased. Is.

  Furthermore, in the non-aqueous electrolyte battery according to the present invention, the compound containing an anion comprising a saccharin group or a derivative thereof is added so as to have a ratio of 0.001 to 10.0% by mass with respect to the non-aqueous electrolyte. preferable. At this time, when the amount is less than 0.001% by mass, film formation on the positive electrode by the compound becomes insufficient, and the effect of suppressing internal resistance by the film becomes insufficient. On the other hand, when the content exceeds 10.0% by mass, the effect of addition, that is, the coating effect of the positive electrode by the compound according to the present invention can be observed, but the excessive film hinders lithium migration and discharge of the positive electrode. Since the reaction is hindered, a sufficient capacity as a battery cannot be exhibited. Furthermore, a preferable ratio will be 0.01-5.0 mass%.

  In the non-aqueous electrolyte battery according to the present invention, a compound having an anion of a saccharin group or a derivative thereof added to the non-aqueous electrolyte contributes to suppression of an increase in internal resistance, thereby improving its storage characteristics. Its industrial value is extremely large.

  Hereinafter, preferred embodiments of the present invention will be described.

  The non-aqueous electrolyte battery according to this embodiment is one in which a power generation element is housed in a well-known battery container such as a cylindrical shape or a coin shape. As the power generation element, a negative electrode material using light metal as an active material is used for the negative electrode, that is, lithium metal or a lithium alloy, and a positive electrode material mainly composed of manganese dioxide is used for the positive electrode.

  Examples of the compound containing an anion comprising a saccharin group or a derivative thereof added to the non-aqueous electrolyte in the present embodiment include the compounds shown in Table 1. In Table 1, additive A is a so-called saccharin in which the cation coordinated to the saccharin group is hydrogen. Additive B is a compound in which the cation coordinated to the saccharin group is a lithium ion. On the other hand, additive C is a compound substituted with an alkyl substituent having 2 carbon atoms (ethyl group) as a saccharin derivative, and additive D is a compound substituted with fluorine which is a group 7B element as a saccharin derivative. These compounds are examples of the embodiment of the present invention, and any compound containing an anion composed of a saccharin group or a derivative thereof can be applied to the non-aqueous electrolyte battery of the present invention. In addition to the configuration in which a single species is added to the non-aqueous electrolyte, these compounds may be configured to select a plurality of compounds and add them to the non-aqueous electrolyte. In the latter configuration, it is preferable to add a plurality of compounds to be added in a ratio of 0.001 to 10.0% by mass with respect to the nonaqueous electrolytic solution as a whole.

  On the other hand, as manganese dioxide applied to the positive electrode in this embodiment, manganese dioxide obtained by a synthesis method such as electrolytic synthesis or chemical synthesis is used as a starting material, and this material is baked. Usually, the manganese dioxide obtained by the synthesis method mentioned above is γ-type manganese dioxide having a γ-type crystal structure. This γ-type manganese dioxide changes its crystal structure by performing a baking treatment, and β-type manganese dioxide having a β-type crystal structure, or a part having a γ-type crystal structure and a part having a β-type crystal structure. It is considered to be a hybrid γ-type / β-type hybrid manganese dioxide. And the manganese dioxide to which these baking processes were performed is applied to the positive electrode which concerns on this embodiment. The temperature conditions in the firing treatment vary depending on various factors such as the physical properties of the crystal structure after firing, the firing time, the firing amount, etc. in addition to the physical properties of the starting material γ-type manganese dioxide. Are determined according to conventional processing conditions.

In addition, the present inventors have conducted detailed studies on manganese dioxide suitable for combination with a compound containing an anion composed of a saccharin group or a derivative thereof added to a nonaqueous electrolytic solution. As a result, it has been found that manganese dioxide having a crystal structure that does not inhibit lithium migration is preferable in a state where a reaction product of manganese dioxide and the above compound forms a film on the positive electrode. Furthermore, as a result of examining the correlation between the treatment conditions in the firing treatment and the discharge characteristics in the non-aqueous electrolyte battery using manganese dioxide obtained by firing, the manganese dioxide according to this embodiment performs firing treatment from 350 ° C. to 450 ° C. It has been found that a temperature range of ° C. is suitable.

  The above-described manganese dioxide according to the present embodiment is used as a positive electrode material by mixing with a known and common conductive agent and binder. Furthermore, instead of manganese dioxide according to the present embodiment, the manganese dioxide and a well-known and commonly used positive electrode material for non-aqueous electrolyte batteries, for example, a positive electrode material mixed with graphite fluoride and iron sulfide may be used. Even in this case, the conductive agent and the binder are combined.

  On the other hand, as a negative electrode material applied to the negative electrode, lithium alloys such as metallic lithium, Li—Al, Li—Si, Li—Sn, Li—NiSi, Li—Pb are applied, and preferably metal Lithium. When the lithium alloy or the like and the additive of the present invention are used in combination, an increase in battery internal resistance during storage is suppressed, and good results are obtained.

Solutes constituting the non-aqueous electrolyte include LiPF ₆ , LiBF ₄ , LiClO ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) A single component such as (C ₄ F ₉ SO ₂ ) or a mixture of a plurality of components can be used. Examples of the solvent for dissolving the solute include propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate, dimethyl carbonate, diethyl carbonate, sulfolane, dimethoxyethane, diethoxyethane, tetrahydrofuran, dioxolane, and γ-butyrolactone. Alternatively, a plurality of components can be used, but the present invention is not limited to this.

  Hereinafter, examples and comparative examples in the present invention will be described. In this example, a coin-type battery having the cross-sectional structure shown in FIG. 1 is produced and evaluated. Needless to say, the present invention is not limited to the description of the examples.

Example 1
First, as Example 1, the effect of battery characteristics by adding a compound containing an anion composed of a saccharin group or a derivative thereof to a non-aqueous electrolyte was examined.

  The positive electrode 4 uses manganese dioxide heat-treated at 400 ° C. as an active material, and this manganese dioxide, carbon powder as a conductive material, and fluororesin as a binder are mixed at a mass ratio of 80:10:10, respectively, and tableting is performed. After molding, it is dried at 250 ° C. The negative electrode 5 is made of lithium metal, and a lithium rolled plate is punched into a predetermined size and fixed to the inner surface of the negative electrode can 2.

On the other hand, as the non-aqueous electrolyte, a solution obtained by dissolving LiClO ₄ at a ratio of 1.0 mol / liter in a solvent in which propylene carbonate and dimethoxyethane were mixed at a volume ratio of 50:50 was used. In this example, as the battery according to the present invention, the compounds A to D shown in Table 1 exemplifying the embodiment of the present invention were selected as additives, and 0.1 mass each for the non-aqueous electrolyte solution. % Is added. Further, the batteries A to D according to the present invention produced as described above were produced, and a battery containing no additive was produced. Using these batteries, each battery was stored in a thermostat at 70 ° C. for one month, and the battery internal resistance before and after storage (AC 1 kHz method) was compared. The results are shown in Table 2.

  In the state before storage, all of the batteries A to D using the electrolytic solution containing the additive according to the present invention have a higher internal resistance value than the comparative battery 1. In particular, the battery C is about 30% higher than the comparative battery 1. The present inventors have examined the internal resistance prior to the examination of this example, and confirmed that there is no practical problem if the value is 14.0Ω or less. On the other hand, after storage, as is clear from Table 2, the batteries A to D according to the present invention are batteries after storage compared to the comparative battery 1 to which a compound containing an anion comprising a saccharin group or a derivative thereof is not added. The increase in internal resistance is suppressed, and the effect of the present invention can be observed. In addition, in the batteries A to D of this example, the battery C to which the compound C was added had the smallest value of increase in internal resistance before and after storage, indicating the best results. From this result, it can be said that Compound C is the most effective additive in the configuration of this example.

(Example 2)
Next, as Example 2, the influence on the amount of compound added to the non-aqueous electrolyte was examined. In Example 2, the battery D having the smallest internal resistance before and after storage in Example 1 was examined. A battery was produced in which the addition ratio of compound D in battery D was varied in the range of 0.0005 to 15.0 mass%. Furthermore, as in Example 1, each battery was stored in a constant temperature bath at 70 ° C. for one month, and the battery internal resistance before and after storage (AC 1 kHz method) was compared. The results are shown in Table 3.

  As is clear from Table 3, in the case of the battery to which the additive of the compound containing an anion composed of the saccharin group or its derivative according to the present invention was added, the inside of the battery during storage compared to the comparative battery 1 at any addition ratio Resistance rise is suppressed. However, when the amount is less than 0.001% by mass, the effect of the addition of the compound is small, and an adverse effect due to an increase in internal resistance is concerned in a severe environment. Moreover, in the case of 10.0 mass% or more, although the addition amount is increasing, the increase in internal resistance is caused. This phenomenon is presumed that the reaction product between the compound and the positive electrode is in an excessive state, and the excessive film causes an increase in internal resistance. Therefore, from the results of Example 2, the addition ratio of the additive D is preferably in the range of 0.001 to 10.0% by mass, and most preferably in the range of 0.01 to 5.0% by mass. Good results are shown.

  In addition, the inventors have also studied the addition ratio from the viewpoint of internal resistance in the same manner as in Example 2 for the additives shown in Table 1, and the preferable addition ratio is in the range of 0.001 to 10.0 mass%. It is confirmed that the optimum addition ratio is in the range of 0.01 to 5.0 mass%.

  As described above, in this example, only the coin type battery in which the additive of the present invention was added to the non-aqueous electrolyte was examined. However, the present invention can exert its effect regardless of the shape of the battery, and can be applied to batteries having various shapes such as a cylindrical shape and a square shape.

  The present invention suppresses an increase in internal resistance by adding a compound having a saccharin group or a derivative thereof as an anion to a non-aqueous electrolyte, and improves the storage characteristics of the non-aqueous electrolyte battery. In particular, it is suitable for a non-aqueous electrolyte battery using manganese dioxide for the positive electrode, and provides high reliability even when the battery is used in a harsh environment.

Sectional view of the coin-type battery in this example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positive electrode can 2 Negative electrode can 3 Gasket 4 Positive electrode 5 Negative electrode 6 Separator

Claims (6)

A non-aqueous electrolyte battery comprising a positive electrode, a negative electrode mainly composed of lithium metal or a lithium alloy, and a non-aqueous electrolyte, wherein the positive electrode is mainly composed of manganese dioxide, and the saccharin group or a derivative thereof is added to the non-aqueous electrolyte. A non-aqueous electrolyte battery characterized in that a compound containing an anion is added. The nonaqueous electrolyte battery according to claim 1, wherein the compound containing an anion comprising a saccharin group or a derivative thereof uses a cation as a hydrogen ion, an alkali metal, or an alkaline earth metal ion. An anion comprising a derivative of a saccharin group includes at least one of R (R is an alkyl substituent having 1 to 3 carbon atoms) or a 7B group element (Cl, F, Br, I) in the ortho position and the para position. Item 3. The nonaqueous electrolyte battery according to Item 2. The nonaqueous electrolytic solution according to any one of claims 1 to 3, wherein the compound containing an anion comprising a saccharin group or a derivative thereof is added at a ratio of 0.001 to 5.0 mass% with respect to the amount of the nonaqueous electrolytic solution. battery. The non-aqueous electrolyte battery according to claim 1, comprising at least one of propylene carbonate, ethylene carbonate, butylene carbonate, and γ-butyl lactone as an organic solvent constituting the non-aqueous electrolyte. 2. The nonaqueous electrolyte battery according to claim 1, wherein manganese dioxide is baked in a range of 350 ° C. to 450 ° C. 3.

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