JPH0677465B2 - Non-aqueous electrolyte battery - Google Patents

Description

The present invention relates to a primary or secondary non-aqueous electrolyte battery using a light metal such as lithium or sodium as a negative electrode active material.

<Prior Art> Non-aqueous electrolyte batteries typified by lithium batteries are lightweight and have high energy density, and various types such as cylindrical spiral type, cylindrical inside-out type, and coin type are used. There is.

In this battery, a negative electrode using lithium, sodium or the like as an active material and a positive electrode using manganese dioxide, carbon fluoride or the like as an active material are combined via an electrolytic solution resistant separator, and the electrolytic solution is not A non-aqueous electrolytic solution prepared by dissolving an alkali metal salt in an aqueous organic solvent is used.

Since the above-mentioned electrolytic solution is required to have high electric conductivity from the viewpoint of discharge performance, it is necessary that the solvent used for it has a high dielectric constant and low viscosity, and shows a high solubility for solutes. is there. In addition, it must have a low melting point and a high boiling point so that it can be used in a wide temperature range and that it has a high flash point or ignition point from the viewpoint of safety.

Among the currently known organic solvents, propylene carbonate substantially meets these requirements, but it has a drawback of high accuracy. Therefore, in the current battery,
A mixed solvent in which a low-viscosity organic solvent such as dioxolane, dimethoxyethane, or tetrahydrofuran is mixed with propylene carbonate is used.

On the other hand, as the solute of the non-aqueous electrolytic solution conventionally used,
LiClO ₄ is the mainstream in terms of battery performance.

However, when this LiClO ₄ is used as the electrolytic solution, there is a danger that the battery will explode due to rapid heat generation due to a large current when the battery is short-circuited, high temperature when the battery is put into a fire, or the like.

For this reason, from the viewpoint of safety, conversion to other solute systems has been urgently made, and various solutes have been proposed. In particular, LiCF ₃ SO ₃
Is a promising solute with high safety.

<Problems to be Solved by the Invention> However, since the electrolytic solution using this LiCF ₃ SO ₃ as a solute has a low electric conductivity and the internal resistance of the battery rises at the beginning and during storage, this is the discharge performance of the battery. Will lead to a decrease in Furthermore, during storage at high temperature, corrosion of the metal member on the positive electrode side is induced. Therefore, when LiCF ₃ SO ₃ is used as the solute, there is a problem in that the discharge performance and the storage performance are degraded in exchange for safety.

Therefore, it is desired to develop a highly safe electrolyte system while maintaining high discharge performance and storage performance. An object of the present invention is to provide a non-aqueous electrolyte battery having such an electrolyte system.

<Means for Solving the Problems> The non-aqueous electrolyte battery of the present invention includes a negative electrode using a light metal such as lithium or sodium as an active material, and manganese dioxide, fluorinated carbon, other metal oxides, metal sulfides, or the like. A positive electrode as a substance, and a non-aqueous electrolytic solution, using a mixed solvent of propylene carbonate, dioxolane and dimethoxyethane as the non-aqueous electrolytic solution, the composition ratio occupied in the mixed solvent of dimethoxyethane 5 to 30% by volume,
LiCF ₃ SO ₃ is the main solute, and LiClO ₄ is 0.005-0.1mo.
The gist is that the l / l solution is used.

The above range is appropriate for the amount of LiClO ₄ dissolved (the amount added).
If it is less than this range, the required discharge performance cannot be obtained, and if it is too large, the safety of the electrolytic solution is impaired.

On the other hand, the amount of LiCF ₃ SO ₃ used in the mixed solvent is not particularly limited, but about 1 mol / l is suitable.

Further, in the above mixed solvent, the composition ratio of dimethoxyethane is appropriately in the range of 5 to 30% by volume. If it is less than this range, it becomes difficult to obtain desired discharge performance. Further, although dimethoxyethane has good characteristics at high temperatures, it has poor characteristics at low temperatures. Therefore, if the proportion of dimethoxyethane in the solvent of this electrolytic solution exceeds 30% by volume, characteristic deterioration at low temperatures becomes remarkable.

<Operation> By using the above-mentioned electrolytic solution, deterioration of discharge performance observed when LiCF ₃ SO ₃ is used alone as a solute, increase in internal resistance at the beginning and during storage, and corrosion during storage at high temperature, etc. It was found that the discharge performance was substantially improved, and that the discharge performance equivalent to that of a battery using an electrolyte system using LiClO ₄ alone as a solute was obtained without impairing the safety of the battery.

Although the reason why the discharge characteristics are improved is not clear, the rapid movement of dissociated ions of LiClO ₄ added in a small amount to the solvent causes the slow movement of dissociated ions of LiCF ₃ SO _{3 having} a larger molecular diameter. It is considered that they worked to help, and that these small amounts of solute acted as effective inhibitors against the corrosion of the positive electrode side metal member during storage at high temperature.

<Example> LiCF ₃ was added to a mixed solvent in which propylene carbonate, dioxolane, and dimethoxyethane were mixed at a volume ratio of 2: 2: 1.
SO ₃ was dissolved in 1 mol / l and LiClO ₄ was dissolved in 0.1 mol / l to prepare an electrolytic solution according to the present invention.

Further, for comparison, an electrolyte solution in which 1 mol / l of LiClO ₄ was dissolved in a mixed solvent of propylene carbonate and dioxolane at a volume ratio of 1: 1 was used as a mixed solvent of propylene carbonate and dimethoxyethanone at a volume ratio of 1: 1. 1 mol / l of LiCF ₃ SO ₃ was added to an electrolyte solution in which 1 mol / l of LiClO ₄ was dissolved, and a mixed solvent of propylene carbonate and dioxolane at a volume ratio of 1: 1.
Dissolved electrolytes were made respectively.

The temperature changes of the conductivity (ms) in these four electrolytic solutions are as shown in FIG. 1, and the electrolytic solution of the present invention significantly improves the conductivity of the conventional LiCF ₃ SO ₃ system over a wide temperature range. , Shows a value close to that of the LiClO ₄ system that is currently commonly used.

Next, an example in which the present invention is applied to a cylindrical spiral lithium battery will be described.

A sheet-shaped positive electrode 1 formed by mixing powder of manganese dioxide with a conductive agent and a binder, and a negative electrode 2 made of a lithium sheet.
And are stacked with a separator 3 made of a polypropylene non-woven sheet and wound in a spiral shape to form a power generating element 4,
This is housed in a battery can 5 made of stainless steel, an insulating gasket 6 made of synthetic resin is placed in the opening of the battery can, and a lead plate 9 led out from the upper part of the positive electrode is spot-welded to a stainless steel sealing plate 8. A predetermined amount of non-aqueous electrolyte is injected, and a stainless steel terminal plate 7, sealing plate 8 and the like are placed on the insulating gasket 6 to squeeze the opening of the battery can. -H type lithium battery was produced.

Here, in the above non-aqueous electrolyte, propylene carbonate, dioxolane, and dimethoxyethane are used in a volume ratio of 2: 2: 1.
LiCF ₃ SO ₃ in 1 mol / l and LiCl in the mixed solvent mixed in the ratio of
O ₄ is 0 (no addition), 0.001, 0.005, 0.01, 0.05, 0.
Fifty batteries were prepared using the non-aqueous electrolyte solutions prepared by dissolving 1, 0.2 and 0.5 mol / l, respectively.

Table 1 shows the initial number of these batteries and the number of occurrence of batteries in which 0CV was abnormally deteriorated after storage for 40 days and 80 days at a temperature of 60 ° C., and LiClO ₄ was added to the electrolyte solution in an amount of 0.
Batteries containing more than 001 mol / l have drastically reduced the number of abnormal deterioration during high temperature storage. As a result of disassembling and examining the battery in which 0CV was abnormally deteriorated, the lead plate on the positive electrode side was found to be corroded, and the separator near this was discolored to black brown, so self-discharge was accelerated in this part. It is probable that this resulted in a decrease of 0 CV.

Moreover, among these batteries, the temperature of 60 ° C. was obtained for each of the batteries A to D in which the amount of LiClO ₄ added was 0 (battery A), 0.001 (battery B), 0.01, battery C) 0.05 mol / l (battery D). When the change in R _AC after 100 days of storage was examined in Fig. 3, the results shown in Fig. 3 were obtained, and as with the above, the increase in the internal resistance of the battery with 0.001 mol / l or more of LiClO ₄ increased at high temperature. It was also small after long-term storage.

Next, we prepared 50 batteries with various amounts of LiCF ₃ SO _{3 and} LiClO ₄ added (mol / l) in the electrolyte, as shown in Table 2. When the number of ruptures of the battery was examined, the results as shown in Table 2 were obtained. From these results, it can be seen that when the amount of LiClO ₄ added is 0.1 mol / l or less, a very safe battery can be obtained.

<Effects of the Invention> As described above, according to the present invention, it is possible to provide a non-aqueous electrolyte battery having high discharge performance and high safety.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing the electric conductivity of a non-aqueous electrolyte according to the present application, FIG. 2 is a cross-sectional view of a battery of an example, and FIG. 3 is a storage of a battery of the example. 6 is a graph showing characteristics. 1 ... Positive electrode, 2 ... Negative electrode, 5 ... Battery can, 7 ... Terminal plate.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiro Harada 5-36-11 Shimbashi, Minato-ku, Tokyo Fuji Electric Chemical Co., Ltd. (72) Inventor Masakazu Kitakata 5-36-11 Shinbashi, Minato-ku, Tokyo Fuji Electric Chemical Co., Ltd. (56) Reference JP-A-59-134568 (JP, A)

Claims (1)

[Claims] 1. A negative electrode using a light metal such as lithium or sodium as an active material, a positive electrode, and a nonaqueous electrolytic solution, wherein a mixed solvent of propylene carbonate, dioxolane, and dimethoxyethane is used as the nonaqueous electrolytic solution. , The composition ratio of dimethoxyethane in the mixed solvent is 5 to 30% by volume,
LiCF ₃ SO ₃ is the main solute, and LiClO ₄ is 0.005-0.1mo.
A non-aqueous electrolyte battery characterized by using a l / l solution.