JPS6041773A - Organic electrolyte battery - Google Patents

Abstract

PURPOSE:To increase the charge-and-discharge characteristic of an organic electrolyte battery by adding a compound such as polyethylene glycol or polyethylene oxide to prepare the electrolyte. CONSTITUTION:In preparing electrolyte for an organic electrolyte battery containing lithium or a lithium alloy as a negative active material, at least one compound chosen from the group consisting of polyethylene glycol, polyethylene oxide, polypropylene glycol, polyethylene oxide, polypropylene glycol, polypropylene oxide and an ethyleneoxide-propyleneoxide copolymer is added. Addition of an insufficient amount of such a compound will result in an insufficient effect, while addition of an excessive amount of such a compound will result in a decreased conductivity due to an increased viscosity of the electrolyte. Therefore, the amount of the additive is preferred to be 0.2-8g per 100ml of the electrolyte.

Description

[Detailed Description of the Invention] An object of the present invention is to improve an organic electrolyte battery as a material, to reduce internal resistance, especially lithium interfacial resistance, and to improve charge/discharge characteristics as a secondary battery. .

Conventionally, organic electrolyte-based secondary batteries using lithium or lithium alloy as an FI electrode active material have not had sufficient charge/discharge reversibility. The cause of this was that the electrodeposited lithium reacted with the electrolytic solution, resulting in deterioration of the negative electrode, and the form of the electrodeposited lithium became dendritic, resulting in a short circuit. Also, in primary batteries, a film is formed on the surface of lithium due to reaction with moisture, etc.
This film was a cause of increasing internal resistance and decreasing closed circuit voltage.

The present invention solves the above-mentioned drawbacks of the prior art, and is intended to provide an organic battery using lithium or a lithium alloy as a negative electrode active material, in which polyethylene glycol,
polyethylene oxide, polypropylene glycol,
The object is achieved by adding at least one member selected from the group consisting of polypropylene oxide and ethylene oxide-propylene oxide copolymer to the electrolytic solution.

In the present invention, the C electrolyte includes, for example, 1,2-dimethoxyconicone, L2-jethoxy]nitane, propylene carbonate, and γ-butyrolactone.

Tetrahydrosolane, 2-methylterahydrofuran, 3-dioxolane, 4-methyl-1,3-dioxolane, 4,4-dimethyl-1,3-dioxolane, 4
, 5-dimethyl-1,3-dioxolane, 2-methyl-
1,3-dioxolane, 2,4-dimethyl-1,3-dioxolane, (CH30)3P-〇, (C2t+5
o) 3 P=O, (C4Its O) 3 P −
〇 , (C8H,) O) 3 P=O, (CI C
l-12C1120) 3P=0 or a mixed solvent of two or more, LiClO4, LiPF5, LiBF
4, I, 1AsF6, LiSbF6, LiAlCl4,
LiBID C1, L, LiB12C112, L
i13(C6H5)4, L i B (p-FCs H
4) 3 CH3, L i B (p-Fe2 H4)
4 etc. Den 1 S? An organic electrolyte solution containing dissolved substances is used.

If the amount of polyethylene glycol, polyethylene oxide, polypropylene glycol, polypropylene oxide, or ethylene oxide/dopropylene oxide copolymer added to the electrolyte is too small, the effect will not be fully exerted, and if it is too large, the viscosity of the electrolyte will increase. 0.2 per 100 mρ of electrolyte, since the conductivity decreases due to the increase in
It is preferable to set it as g-8g.

In the organic electrolyte battery of the present invention, as the negative electrode active material, lithium, lithium and, for example, aluminum, mercury,
Lithium alloys with zinc, cadmium, etc. are used, and i-substances for the positive electrode include iron sulfides such as titanium disulfide, iron disulfide, ferrous sulfide, and ferric sulfide, manganese dioxide, and (C12) metals. , (C2F):l:, niobium disulfide, V60B, Cu5V201D, etc. are used.

Next, the present invention will be explained with reference to Examples.

Example I LiB(Csl15)4 was combined with 1,3-dioxolane and 1.
Container 17 with 2-dino-1-31-ethane 75:
2.4 g/100 m (l) of polyethylene glycol (average molecular weight: 20.000) was added to an organic electrolyte solution prepared by dissolving 0.6 mol/l/8 in 25 l/l footstock solvent.
) Is it added in proportion? g made me understand. Using an electrolytic solution to which polyethylene glycol has been added in this way, in order to eliminate the influence of the counter electrode, L i / L as shown in Fig. 1 is used.
The charge and discharge characteristics were investigated using an i model cell. The charging and discharging characteristics were measured by charging and discharging the battery at a constant current of 1 mA and checking the number of cycles in which the polarization voltage between the test electrode and the counter electrode was 1 V or less.

In FIG. 1, 1 is a polypropylene holding plate, the test electrode 2 is formed by pressing lithium boiling 4 on both sides of a stainless steel net 3, and the counter electrode 5 is formed by pressing lithium foil 7 on both sides of a stainless steel net 6. It is formed by crimping. 8 is a current collector lead on the test electrode side, 9 is a current collector lead on the counter electrode side, 10.11 is a microporous polypropylene film, 12.13 is a polypropylene nonwoven fabric, 14 is an electrolytic solution, and 15 is a sealed It is a glass container.

Comparative Example 1 The same electrolyte as in Example 1 was used except that polyethylene glycol was not added, and the same Li as in Example 1 was used.
The charging and discharging characteristics were evaluated using the /li model cell.

Table 1 shows the charging and discharging characteristics of Example 1 as an index when the charging and discharging characteristics of Comparative Example 1 are taken as 100.

Table 1 Example 2 LiB (C611s)4 was mixed with 4-methyl-1,3-dioxolane and 1,2-dimethoxyethane at a ratio of 75.
: 4 g/10 of ethylene oxide-doped 1-pyrene oxite copolymer (average molecular weight 12,000) was dissolved in an electrolytic solution of 0.6 mol/p/8 dissolved in a mixed solvent of 25
It was added at a rate of 0 mn to give a solution of /8.

Using the electrolyte I11 liquid to which the ethylene oxide dipropylene oxide copolymer was added in this manner, the charge/discharge characteristics were investigated using a l-i/Li'F-del cell as shown in FIG.

Ratio Example 2 The same electrolytic solution as in Example 2 was used except that the ethylene oxide-propylene oxide copolymer was not added.
As in Example 2, the charge/discharge characteristics were investigated using the Li/Li model cell.

Table 2 shows the charging and discharging characteristics of Example 2 as an index when the charging and discharging characteristics of Comparative Example 2 are taken as 100.

Table 2 Example 3 L i B (p-FCs H4) 3 C113 to 4
- 1.0 in a mixed solvent of methyl-1,3-dioxolane and 1,2-dimethoxyethane with a plasticity ratio of 75:25.
1 g/100 of polypropylene glycol (average molecular weight 4,000) in the electrolyte solution obtained by melting mol/β
Is your speaking ability as a percentage of mρ? I let it happen.

Using the electrolytic solution to which polypropylene glycol was added in this way, the charge and discharge characteristics were investigated using an I, Violet/Li model cell as shown in FIG.

Comparative Example 3 The same electrolyte as in Example 3 was used except that polypropylene glycol was not added, and Li/
The charge and discharge characteristics were investigated using a Li model cell.

Table 3 shows the charging and discharging characteristics of Example 3 as an index when the charging and discharging characteristics of Comparative Example 3 are taken as 100.

Table 3 As shown in Tables 1 to 3, the addition of polyethylene glycol, ethylene oxide-propylene oxide copolymer, polypropylene glycol, etc. improved the charge-discharge characteristics.

Next, complex plane analysis diagrams of Examples 1 to 3 and Comparative Examples 1 to 3 are shown in FIGS. 2 to 3. Measurement is 55kllz ~ 20m112
was carried out within the range of FIG. 2 shows the state before charging and discharging, and FIG. 3 shows the state after 10 cycles of charging and discharging. In addition, in FIGS. 2 and 3, Example 1 is A, Example 2 is B, and Example 3 is C.
Comparative Example 1 is indicated by U, Comparative Example 2 is indicated by ■, and Comparative Example 3 is indicated by W.

As is clear from the results shown in Figures 2 and 3, the interfacial resistance of lithium, that is, the resistance value that is related to the diameter of the semicircle in the figure, is smaller in the example of the present invention than in the comparative example. It can be seen that in Examples, the formation of a lithium surface film is small. It is thought that this is because the additives used are effective in removing the lithium surface skin.

Example 4 Using the same polyethylene glycol-added electrolyte as in Example 1, a button-shaped battery with a diameter of 20 mm and a length of 1.6 mm was assembled. The battery has a negative electrode made of lithium, and a positive electrode made of a titanium disulfide mixture with titanium disulfide as the positive electrode active material.The separator is made of a superimposed layer of microporous polypropylene film and polypropylene nonwoven fabric. It was placed so as to face the negative electrode surface.

Comparative Example 4 A button-shaped battery was assembled in the same manner as in Example 4, except that the same electrolyte as in Comparative Example 2 was used.

Example 5 A button-shaped battery was assembled in the same manner as in Example 4, except that the same electrolytic solution as in Example 2 to which the ethylene oxide-propylene oxide I co-Qj combination was added was used.

Comparative Example 5 A button-shaped battery was assembled in the same manner as in Example 5, except that the same electrolyte as in Comparative Example 2 was used.

Example 6 A button-shaped battery was assembled in the same manner as in Example 4, except that the same polypropylene glycol-added electrolyte as in Example 3 was used.

Comparative Example 6 A button-shaped battery similar to that of Example 6 was assembled except that the same electrolyte as that of Comparative Example 3 was used.

Examples 4 to 6 and Comparative Examples 4 to 6 obtained as described in 1.
The closed circuit voltage of the battery No. 6 was measured after discharging at 20°C and 1300Ω for 5 seconds. The results are shown in Table 4.

Table 4 shows the temperature of the batteries of Examples 4 to 6 and Comparative Examples 4 to 6 at 20°C.
, 2 shows the discharge characteristics when continuously discharging with a constant Ω resistance.
As shown in the figure. In addition, in FIG. 4, the battery of Example 4 I)
The battery of Example 5 is E, the battery of Example 6 is F, the battery of Comparative Example 4 is X, the battery of Comparative Example 5 is Y, and the battery of Comparative Example 6 is
The battery is indicated by Z.

As shown in Table 4 and FIG. 4, all of the batteries of the present invention have higher closed circuit voltages than the corresponding comparative batteries;
And the discharge duration is long. This is polyethylene green 1-
Ethylene oxide 1゛-propylene oxide copolymer, Volipl',! This is thought to be due to the fact that the resistance of the lithium interface became lower due to the addition of pyrene glycol or the like.

[Brief explanation of drawings]

Figure 1 shows 1. , i/Li model cells are not shown and are cross-sectional views, and Figures 2-3 are Examples 1-3 (indicated by A-C).
and Comparative Examples 1 to 3 (indicated by U-W). Fig. 2 shows the state before charging and discharging, and Fig. 3 shows the state after 10 cycles of charging. 'Iii& state is shown. Figure 4 shows Example 4~
6 batteries (indicated by 1 to Z) and comparative examples 4 to 6 batteries (X
−Z) indicates the discharge characteristic lνI of 2...test electrode,
5...Counter electrode, 14...Electrolyte i figure 2nd person register person rn> Figure 3 person person person tan person (-'1-)

Claims (1)

[Claims] fil In an organic electrolyte battery using lithium or a lithium alloy as a negative electrode active material, the electrolyte contains at least one member selected from the group consisting of polyethylene glycol, polyethylene oxide, polypropylene glycol, polypropylene oxide, and ethylene oxide-propylene oxide copolymer. An organic electrolyte battery characterized by adding.