JPH0574192B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a non-aqueous electrolyte battery using a light metal such as lithium or sodium as a negative electrode active material. <Prior art> This type of nonaqueous electrolyte battery, such as a lithium battery, is a lightweight, high-energy-density battery, and comes in various types such as a cylindrical spiral type, a cylindrical inside-out type, a coin type, and a pin type. are widely used. These batteries employ a configuration using a non-aqueous electrolyte in which an alkali metal salt is dissolved as an electrolyte in a non-aqueous organic solvent. Current batteries generally use a solvent consisting of organic solvents such as propylene carbonate, dimethoxyethane, or tetrahydrofuran alone or in combination, and a non-containing battery made by dissolving an electrolyte mainly consisting of LiClO ₄ in this solvent. A water electrolyte is used. <Problems to be Solved by the Invention> However, in this type of battery, the positive and negative electrodes may be short-circuited during assembly, and after assembly, for example, the positive electrode current collector and the negative electrode may be short-circuited inside the battery. When there is a short circuit between the positive electrode lead plate and the negative electrode can, rapid heat generation occurs. Further, heating from the outside, such as when the battery is short-circuited to the outside after assembly or thrown into a fire, also causes a rise in battery temperature. When LiClO ₄ is used as an electrolyte as described above, when this temperature rises, LiClO ₄ in the electrolyte
In addition, there is a high risk of explosion due to the effects of this, and there is a problem that it is difficult to handle. In particular, in the case of a cylindrical spiral battery, this risk is particularly high because the temperature of the battery rises rapidly due to the large current that flows during a short circuit. For this reason, from the standpoint of safety, there is an urgent need to switch to other solutes other than LiClO ₄ , but in many cases this leads to a decrease in battery performance at the cost of improved safety. The development of an electrolyte system with high performance is desired. <Means for Solving the Problems> The non-aqueous electrolyte battery of the present invention includes a negative electrode whose active material is a light metal such as lithium or sodium, a positive electrode, and a non-aqueous electrolyte formed by dissolving an electrolyte in an organic solvent. , the organic solvent has ethoxymethoxyethane (EME) as a main component, and the electrolyte uses any one of LiCF ₃ SO ₃ , LiPF ₆ , LiBF ₄ , and LiAsF ₆ as at least one component, and further comprises The gist is that LiClO ₄ was added as an electrolyte in a molar ratio of 0.005 to 0.2 with respect to the electrolyte. By the way, when LiCF ₃ SO ₃ is used as the solute,
Corrosion of the positive electrode side lead plate and battery can may be observed, which is thought to be caused by free fluorine contained in the solute itself or acids generated by hydrolysis of the solute and trace amounts of moisture in the battery. may affect storage performance. In this case, it is known that the above-mentioned corrosion can be effectively suppressed by adding a small amount of LiClO ₄ as an electrolyte to the above-mentioned electrolytic solution. The reason for this anti-corrosion effect is unknown, but a small amount of
It is presumed that LiClO ₄ is used as a so-called inhibitor. You can also use _LiClO4 like this
It was found that the power distribution performance of the battery was also improved with the addition of . When LiClO ₄ is contained in the electrolyte in this way, for example, when LiCF ₃ SO ₃ is used as the main electrolyte, the molar ratio of LiClO ₄ to LiCF ₃ SO ₃ [(molar concentration of LiClO ₄ in the electrolyte)] /(Molar concentration of LiCF ₃ SO ₃ in the electrolytic solution)] is found to be preferably in the range of 0.005 to 0.2. If the amount is less than this, the corrosion-preventing effect will be insufficient and corrosion cannot be completely prevented, whereas if it is more than this, problems will arise from a safety point of view. On the other hand, in addition to ethoxymethoxyethane as the main component, the above-mentioned organic solvents include ester-based organic solvents (high dielectric constant solvents) such as propylene carbonate and ethylene carbonate in order to maintain and improve the special properties of the battery. can be used. <Function> As described above, using an electrolyte solvent containing ethoxymethoxyethane as the main component, LiCF ₃ SO ₃ as the solute,
It is known that by using either LiPF ₆ , LiBF ₄ , or LiAsF ₆ and adding a trace or small amount of LiClO ₄ to this, a highly safe battery with almost no deterioration in battery performance can be obtained. . Additionally, this ethoxymethoxyethane has a flash point of 20°C, which is much higher than dimethoxyethane and tetrahydrofuran, which have traditionally been used as electrolyte solvents, and this also contributes to improved battery safety. are doing. <Example> Below, an example in which the present invention is applied to a lithium battery will be described in detail. Inside a bottomed cylindrical battery can 1 made of stainless steel, there is a belt-shaped positive electrode 2 formed into a sheet of a mixed powder containing manganese dioxide as a main component, to which graphite powder as a conductive agent and a binder are added; A power generation element 5 made by stacking a negative electrode 3 made of a lithium sheet and a separator 4 made of a propylene nonwoven sheet and winding them in a spiral is housed, and a lead terminal led out from the negative electrode on the bottom side of the power generation element. 6 is bent toward the bottom side of the battery can through an insulating plate 7 and spot welded to the inner bottom surface of the battery case, while a predetermined amount of a pre-prepared non-aqueous electrolyte 8 is injected, and a lead terminal 9 led out from the upper part of the positive electrode is For example, by connecting it to a plate-shaped terminal plate 12 made of stainless steel placed on the opening of the battery can inside the insulating gasket 10 made of synthetic resin,
CR6/H type (outer diameter 14.5
A spiral-shaped lithium battery with a diameter of 50.5 mm and a height of 50.5 mm was fabricated. The non-aqueous electrolyte used was one in which 0.9 mol/LiCF ₃ SO ₃ was dissolved as an electrolyte in a solvent in which propylene carbonate and ethoxymethoxyethane were mixed at a volume ratio of 1:1. . Also, the molar ratio of LiClO ₄ to LiCF ₃ SO ₃ is
Various similar electrolytic solutions were prepared except that the amount of ions was added in the range of 0.005 to 0.2, and CR6/H type spiral lithium batteries were fabricated using these electrolytic solutions in the same manner. Then, we made 50 of each of these batteries, and calculated the number of 0CV abnormal deteriorations immediately after battery production (first time), after storage at 60℃ for 40 days after fabrication, and after storage at 60℃ for 100 days after fabrication. Upon investigation, the results shown in Table 1 were obtained.

[Table] When we disassembled and examined the batteries that had abnormally deteriorated at 0CV, we found that the lead plates on the positive electrode side of these batteries were corroded, and the separator near them was discolored to a blackish-brown color. It is thought that self-discharge, which appears to be caused by corrosion, was promoted in this discolored area, leading to a decrease in 0CV. In addition, we made 30 batteries each in which the amount (molar ratio) of LiClO ₄ to LiCF ₃ SO ₃ added in the electrolyte was varied in the range of 0.1 to 0.30, and calculated the number of ruptures when the batteries were placed in a fire. The results were as shown in Table 2, and it was found that a highly safe battery could be obtained by setting this molar ratio to 0.20 or less.

[Table] Furthermore, the amount (mole ratio) of LiClO ₄ added to LiCF ₃ SO ₃ is 0 (no addition: battery), 0.001 (battery), 0.0005 (battery), 0.01 (battery), 0.1 (battery), 0.2 (battery) and batteries using different electrolytes were made, and the changes in R _AC (Ω) when these batteries were stored at 60°C were investigated, and the results shown in Figure 2 were obtained. It was confirmed that the _RAC characteristics after storage were significantly improved by adding a trace to a small amount of LiClO ₄ . In addition, the above is the main solvent that dissolves in the electrolyte.
This is an example using LiCF ₃ SO ₃ , but in addition, LiPF ₆ ,
A similar or second best effect was obtained when LiBF ₄ or LiAsF ₆ was used. In addition, in the above example, manganese dioxide was used as the positive electrode active material and lithium was used as the negative electrode active material, but carbon fluoride, metal oxides such as MoO ₃ and CuO were used as the positive electrode active material. ,
Similar results can be obtained when metal sulfides such as CuS and Ni ₃ S ₂ are used, and other light metals such as sodium and potassium are used as the negative electrode active material. Moreover, although the above is an example of a cylindrical spiral type battery, it goes without saying that similar results can be obtained with other types of batteries such as a cylindrical inside-out type, a coin type, or a pin type. <Effects of the Invention> As described above, according to the present invention, a battery with high battery performance and high safety can be provided.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a battery according to an embodiment of the present invention, and FIG. 2 is a graph showing storage characteristics of the battery according to the embodiment. 1...Battery can, 2...Positive electrode, 3...Negative electrode, 6...
...Nonaqueous electrolyte, 12...Positive terminal.

Claims (1)

[Claims] 1. A negative electrode containing a light metal such as lithium or sodium as an active material, a positive electrode, and a non-aqueous electrolyte prepared by dissolving an electrolyte in an organic solvent, the organic solvent mainly containing ethoxymethoxyethane. The electrolyte contains LiCF ₃ SO ₃ , LiPF ₆ , LiBF ₄ ,
LiAsF ₆ is used, and LiClO ₄ is used as another electrolyte at a molar ratio of 0.005 to the electrolyte.
A non-aqueous electrolyte battery characterized by adding an electrolyte in the range of 0.2.