JPH0610994B2 - Organic electrolyte battery - Google Patents

Description

TECHNICAL FIELD The present invention relates to a primary battery and a secondary battery using an organic electrolyte.

2. Description of the Related Art Organic electrolyte batteries are expected to have higher energy density than batteries using conventional aqueous solutions, and are being actively researched as primary batteries and secondary batteries. Among them, a battery using lithium for the negative electrode and fluorocarbon, manganese dioxide, or copper oxide for the positive electrode has already been put to practical use as a primary battery with high energy density.

As the electrolyte of these organic electrolyte primary batteries, lithium perchlorate (LiClO ₄ ) or lithium borofluoride (LiBF ₄ ) dissolved in propylene carbonate (PC) or r-butyrolactone (r-BL), or PC and dimethoxy is used. Ethane (DME), those dissolved in a mixed solvent of PC and dioxolane (DiOx) have been used.

Further, it has recently been reported that, as an organic electrolyte secondary battery, so-called synthetic metal such as titanium disulfide (TiS ₂ ), polyacetylene, polypyrrole, and polyaniline exhibits good characteristics as a positive electrode.

On the other hand, also in the negative electrode, in addition to a lithium metal electrode, fusible gold or aluminum is used, and an electrode that occludes lithium ions in the electrolytic solution by charging and releases lithium ions into the electrolytic solution as lithium ions by discharging, or polyacerene or polyaniline. Electrodes that use lithium ions and tetrabutylammonium ions in the electrolyte solution by charging and discharge by discharging are being studied.

As the electrolyte of these secondary batteries, in addition to the same electrolyte as the primary battery described above, 2-methyltetrahydrofuran is used as the solvent and lithium hexafluoroarsenate (LiAs is used as the solute).
Combinations such as F ₆ ) and tetrabutylammonium perchlorate are being studied.

Problems to be Solved by the Invention In the organic electrolyte battery using the negative electrode and the positive electrode described above,
There are drawbacks such as low discharge voltage and low charge / discharge efficiency in secondary batteries. The present invention remedies these drawbacks.

Means for Solving the Problems The present invention is an organic electrolyte battery using an electrolyte composed of at least one organic solvent and at least one solute, wherein a compound having a uron ring is used as the organic solvent. Compounds having a uron ring are generally
It is expressed in the form of equation (1). Here, R and R ″ are hydrogen or an alkyl group.

In addition, the negative electrode contains a synthetic metal such as fusible gold, aluminum, polyacetylene, etc., which absorbs cations in a electrolyte other than lithium by charging and releases it by discharging, and the positive electrode contains metal oxides, metal chalcogenides, fluorocarbons, Further, synthetic metals such as polyacetylene, polypyrrole, and polyaniline which occlude anions in the organic electrolyte by charging and release by discharging are used.

Lithium salts such as lithium perchlorate, lithium borofluoride and lithium hexafluorophosphate, and quaternary ammonium perchlorate salts such as tetrabutylammonium perchlorate are used as solutes that dissociate into anions and cations in the electrolyte. To be The mixed solvent medium for dissolving these solutes is tetrahydro-3-methyl-5-isobutyl-4H shown in the formula (2).
-1,3,5-oxadiazin-4-one and tetrahydro-3-ethyl-5-isopropyl-4 represented by the formula (3)
H-1,3,5-oxadiazin-4-one, tetrahydro-3-ethyl-5-isobutyl-4H represented by formula (4)
-1,3,5-oxadiazin-4-one and the like containing at least one compound having a uron ring in an amount of 10% by volume or more, and other components include propylene carbonate, ethylene carbonate, r-butyrolactone and dimethoxy. One or a combination of two or more of ethane, dioxolane, 4-methyldioxolane, tetrahydrofuran, 2-methyltetrahydrofuran is used.

Action The solubility of the above-mentioned lithium salt or quaternary ammonium salt in the compound having a uron ring is up to 0.2 mol / l, which is inferior to those using conventional PC or r-BL.

Further, the electric conductivity of the electrolyte obtained by dissolving the solute to the saturated state is about 2 × 10 ⁻⁴ Ω ⁻¹ · cm ^−1, which is about
5 × 10 ^{-3 of} electrolyte solution in which mol / LiClO ₄ is dissolved in PC
Ω ⁻¹ · cm ⁻¹ , which is ¹ to 2 orders of magnitude lower than 1.4 × 10 ⁻² Ω ⁻¹ , cm ⁻¹ of electrolysis dissolved in a 1: 1 mixed solvent of PC and DME.

However, in the low rate discharge, metal oxides such as MnO ₂ and CuO, metal chalcogenides such as TiS ₂ , FeS ₂ , CuFeS ₂ ,
A battery using a fluorocarbon or a synthetic metal such as polyacetylene or polypyrrole has a higher discharge voltage than a battery using a conventional electrolytic solution, and a secondary battery has improved charge / discharge efficiency. Furthermore, for the negative electrode, polyacetylene,
It was also found that the secondary battery using polyaniline also showed an improvement in charge and discharge efficiency and a lower discharge voltage, which improved the characteristics of the negative electrode.

It is considered that this is because the wetting of the electrode was improved as compared with the conventional electrolytic solution system using PC, r-BL, or DME, but the detailed reason is not clear.

Furthermore, by using a mixed solvent containing 10% by volume or more of a compound containing a uron ring and adding PC, r-BL, DME and the like as other components, the solubility of the solute is increased as an electrolytic solution, and the electric conductivity is increased. As a result, the discharge voltage is improved and the charge / discharge efficiency is improved in the secondary battery even at high rate discharge as compared with the case of using a conventional electrolyte.

Examples Hereinafter, examples of the present invention will be described.

Example 1 Metal lithium was used for the negative electrode, and fluorocarbon was used for the positive electrode active material. The positive electrode was prepared by adding 100 parts by weight of fluorocarbon, 20 parts by weight of acetylene black as a conductive agent, and 10 parts by weight of polytetrafluoroethylene as a binder, and mixing them well to obtain a mixture. This mixture 0.
5 g of the mixture was press-molded to a size of 2 cm × 2 cm so that titanium expanded metal as a current collector was embedded in the mixture.

The mixture on the end of the positive electrode was removed, and a titanium ribbon as a lead was spot-welded to the current collector. The electrical capacity of the positive ring is 332 mAh.

As the negative electrode, a nickel net was pressure-bonded to one surface of lithium having a size of 2 cm × 2 cm and a thickness of 0.2 mm, and a lead was taken from the end of the net with a nickel ribbon, and the theoretical electric capacity was 1600 mAh. The positive electrode and the negative electrode were placed in a battery case so as to be in close contact with each other via a polypropylene non-woven fabric as a separator. An electrolyte was put in this and vacuum impregnated to include the electrolyte in the positive electrode mixture.

A schematic diagram of this battery is shown in FIG. In the figure, 1 is a positive electrode, 2 is a negative electrode, 3 is a separator, 4 is an electrolyte, and 5 is a battery case.

As the electrolyte, 0.2 mol / LiBF ₄ was dissolved, (2)
A battery using tetrahydro-3-methyl-5-isobutyl-4H-1,3,5-oxadiazin-4-one represented by the formula is defined as A, and tetrahydro-3-ethyl-5 represented by the formula (3) is used. A battery using isopropyl-4H-1,3,5-oxadiazin-4-one was designated as B, and tetrahydro-3-ethyl-5-isobutyl-4H- represented by the formula (4) was used.
A battery using 1,3,5-oxadiazin-4-one is designated as C.

A battery using r-BL in which 1 mol / LiBF ₄ was dissolved in Comparative Example was used as an electrolyte in which 1 mol / LiBF ₄ was dissolved in a mixed solution of D, r-BL and DME in a volume of 1: 1. Let the battery be E. Fig. 2 shows the discharge curves of these batteries at 20 ° C and 1 mA constant current discharge. As is clear from the figure, in the low rate discharge, the discharge voltages of the batteries A, B and C using the electrolyte of the present invention are high. Also, A,
Comparing B and C, AB> C, and the smaller the number of carbons in the molecule, the better the battery performance.

Example 2 A battery having the same structure as in Example 1 was used, and only the electrolyte was changed. The solute is LiBF ₄ and its concentration is 1 mol / mol. Electrolyte solvent, tetrahydro-3-ethyl-5-
Isopropyl-4H-1,3,5-oxadiazine-4
A battery using a solvent in which 70% by volume of DME is mixed with 30% by volume of on-state is F, and a battery using a solvent in which 70% by volume of propylene carbonate is mixed is G. As a comparative example, 50% by volume is: A battery using a mixed solvent of 50 r-BL and DME is designated as H. FIG. 3 shows a discharge curve when constant current discharge of 30 mA was performed at 20 ° C. As is clear from FIG. 3, by using the mixed solvent containing tetrahydro-3-ethyl-5-isopropyl-4H-1,3,5-oxadiazin-4-one, it is possible to obtain a high discharge even at a high rate discharge. It can be seen that it shows voltage.

FIG. 4 shows tetrahydro-3-ethyl-5-isopropyl-4H-1,3,5-oxadiazin-4-one and D
FIG. 3 is a plot of the mixing ratio when the same test as above was performed with the mixing ratio of ME changed, and the battery voltage one hour after the start of discharge. From this, it is understood that the ratio of the compound having a uron ring becomes remarkable when the volume ratio is 10% or more.
If the ratio exceeds 60%, the battery voltage during high-rate discharge decreases. This is because the decrease in the electric conductivity of the electrolyte becomes remarkable. However, as shown in Example 1, in the low rate discharge, the discharge voltage is high even with the electrolyte using the compound having the uron ring as the solvent.

Further, a system using a compound having various uron rings other than tetrahydro-3-ethyl-5-isopropyl-4H-1,3,5-oxadiazin-4-one and a mixed solvent such as PC and DME was examined. As a result, tetrahydro-3
Similar results were obtained with -ethyl-5-isopropyl-4H-1,3,5-oxadiazin-4-one.

In the above examples, an example in which fluorocarbon was used as the positive electrode active material was shown. However, in addition to this, metal oxides such as MnO ₂ and CuO,
Similar effects were observed when metal chalcogenides such as TiS ₂ , FeS ₂ , and CuFe ₂ were used.

Example 3 An example of a secondary battery in which polyacetylene is used for both the negative electrode and the positive electrode, and the negative electrode is used to dove and dedope cations in the electrolyte by charging and discharging, and the positive electrode is doped and dedoped with anions will be described.

For both the positive and negative electrodes, a polyacetylene film having a size of 2 cm × 2 cm and a thickness of 0.1 mm was used. Tetrahydro-
3-Methyl-5-isobutyl-4H-1,3,5-oxadiazin-4-one is used, to which 0.2 mol / mol of
A battery using an electrolyte in which LiClO ₄ is dissolved is used for IPC and DME.
Let J be a battery in which 1 mol / liter of LilO ₄ having a volume ratio of 50:50 was dissolved.

After charging these batteries at 1mA for 3 hours, 1mA
The battery was repeatedly charged and discharged until the terminal voltage reached 1.5V. FIG. 5 shows the results of measuring changes in the potentials of the positive electrode and the negative electrode with respect to the lithium reference potential during discharge in the fifth cycle. From this, it is understood that in the battery I, the discharge potential of the positive electrode is high and the discharge potential of the negative electrode is low, and the terminal voltage of the battery is high. Further, in the battery I, it can be seen that the charging / discharging efficiency is improved due to the longer discharge time.

Further, the same effect was obtained by using a synthetic metal such as polypyrrole or polyaniline for the positive electrode. Further, the same effect was obtained even when a synthetic metal such as polyaniline other than polyacetylene was used for the negative electrode.

As the solute of the electrolyte, lithium salts such as LiBF ₄ and LiPF ₆ ,
Even when using a quaternary ammonium salt such as tetrabutylammonium perchlorate, it is better to use tetrahydro-3-methyl-5-isobutyl-4H-1,3,5-oxadiazin-4-one as a solvent. The characteristics were obtained.

The ratio of tetrahydro-3-methyl-5-isobutyl-4H-1,3,5-oxadiazin-4-one in the mixed solvent is remarkable at 10% by volume or more, and when it exceeds 60% by volume, the effect decreases. Come on. This is because the electric conductivity of the electrolyte is reduced, and when a low rate discharge is performed, tetrahydro-3-methyl-5-isobutyl-4H-1,3,5-oxadiazin-4-one alone solvent is used. As compared with the case of using the conventional electrolyte, the effect of increasing the discharge voltage and improving the charge / discharge efficiency becomes remarkable.

Further, as a result of various studies on compounds having a uron ring, it was found that the number of carbon atoms in the molecule is preferably about 5 to 9, particularly 7 to 9 in terms of charge / discharge efficiency.

In addition, using fusible gold or aluminum as the negative electrode material, a negative electrode of the type that occludes lithium in the electrolyte by charging and discharges lithium by discharging, and a secondary battery using TiS ₂ or MnO ₂ for the positive electrode As in Example 3, it was found that the use of the organic electrolyte using the compound having a uron ring of the present invention makes the potential and charge / discharge efficiency excellent.

EFFECTS OF THE INVENTION As described above, according to the present invention, the discharge voltage is improved in the organic electrolyte primary battery and the charge / discharge efficiency is improved in the secondary battery.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a battery of an embodiment of the present invention, FIGS. 2 and 3 are diagrams showing comparison of discharge characteristics, and FIG. FIG. 5 is a diagram showing the discharge characteristics of the secondary battery by the potential changes of the positive electrode and the negative electrode. 1 ... Positive electrode, 2 ... Negative electrode, 3 ... Separator, 4 ... Electrolyte solution.

Claims (1)

[Claims] 1. A single compound having a uron ring in the molecule,
Alternatively, an organic electrolyte battery comprising an electrolyte composed of a mixed solvent containing this as one component and at least one solute dissolved in the solvent.