JPS5842175A - Nonaqueous electrolyte cell - Google Patents

Abstract

PURPOSE:To obtain the nonaqueous electrolyte cell having a superior discharge characteristic, in particular superior low temperature heavy load characteristic in the last period of electric discharge by regulating the S-value defined as the amount (mul) of electrolyte per active mass (mAH) in positive or negative electrode. CONSTITUTION:This nonaqueous electrolyte cell is based on the finding that the low temperature heavy load characteristic in the last period of electric discharge is markedly improved in consideration of the balance between the amount of active mass and the amount of electrolyte, and the S-value defined as[amount E(mul) of electolyte/capacity C (mAH) of active mass]is regulated within 0.8<= S+<=1.3 and 0.8<=S-<=1.2 in which S+ E/C+, S- E/C- for each of positive elec trode active mass C+ and negative electrode active mass C-.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses lithium as a negative electrode active material, metal oxides, sulfides, halides, etc. as a positive electrode, and PO9γ-butyrolactone, DMIIi, tetrahydrofuran, etc. alone or in a mixed solvent, As a supporting electrolyte, Li0J104.
LiBF'4. The present invention relates to a nonaqueous electrolyte battery using a nonaqueous electrolyte in which an ionically dissociated polarized salt such as LiAs1F4 is dissolved.

An object of the present invention is to provide a nonaqueous electrolyte battery that has high energy density and excellent discharge characteristics, especially heavy load characteristics at low temperatures at the end of discharge.

In a battery, one of the most important characteristics is the energy that can be taken out per unit volume (energy density) or the amount of electricity (capacity density).

This is especially true in an era where small electronic devices have made remarkable progress in recent years, and batteries are required to be smaller, have higher energy density, and have higher capacity density.

On the other hand, in non-aqueous electrolyte batteries, the increase in internal resistance is generally large at the end of discharge, especially at low temperatures below 0°C, so the output when discharging under heavy load at the end of discharge is large. Because of the tendency for voltage to drop rapidly, when connected to elements that require pulsed large current discharges, such as lamps and speakers, which are often incorporated in small electronic devices such as those mentioned above, the output voltage of the battery decreases. In some cases, the temperature gradually decreases to below a certain threshold value, causing malfunction of the XO or display failure of the liquid crystal display. For this reason, conventional batteries have had sufficient remaining capacity and characteristics under normal usage conditions under light loads, but have been shown to suffer from malfunctions due to voltage drops during heavy load pulse discharges (especially at low temperatures). This causes the problem that the actual battery capacity decreases because it is determined that the battery life has expired.

There are several reasons for this. First, the non-aqueous electrolyte described above generally has a specific ion conductivity that is 2 to 5 orders of magnitude lower than that of an aqueous electrolyte, and thus inherently has a large internal resistance. In addition, in this type of battery,
In many cases, the positive electrode swells as discharge progresses, and the electrolyte is absorbed into the positive electrode mix, causing the negative electrode (and sometimes the positive electrode itself) to suffer from a kind of electrolyte shortage, and the effective reaction area for battery reactions is reduced. It is possible that this will decrease. Furthermore, conventionally, high capacity.

In order to achieve high energy density, methods have been used to fill as much active material as possible. In this case, there is no problem from the early stage to the middle stage of discharge, but from the middle stage to the final stage, the active material is considered to be in a liquid shortage state and the internal resistance increases.

The present invention was made in consideration of the above-mentioned problems, and by considering the balance between the amount of active material and the amount of electrolyte in a non-aqueous electrolyte battery, the low-temperature heavy load characteristics at the end of discharge can be improved. This is based on the discovery that there is a significant improvement. That is, (electrolyte amount m[:, aA)/active material capacity c
(sAg)) For each of the 5flits positive electrode active material capacity 0+ and negative electrode active material capacity C−,
When B+th X/O+ *s-wmz7a-, it is proposed to restrict a8≦S+≦t5 and α8≦8-≦t2.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Examples of iron disulfide yes @ particles below 91 S OOtl s and graphite and acetylene plastic as conductive agents? The composition ratio is 85:! :5, a hole mixture of 12 and a solution obtained by adding water and ethyl alcohol to the Teflon dicing solution were added and thoroughly kneaded. The width of this slurry mixture is 1
0 es, JIL size 1.61B sheet, 7
After semi-drying at a temperature of 0° C. or lower, it was integrally formed into a pellet together with the positive electrode pedestal 6. A positive electrode was prepared by heating and drying the bottom-shaped mixture of Otsu at t-50°C for 1 hour and then at 200°C for 2 hours.

FIG. 1 is a cross-sectional view of a battery showing an example of this embodiment. In FIG. 0, 1 is a negative electrode can that also serves as a negative electrode frame, and
A negative electrode current collector 2 made of a metal net is welded. The negative electrode 5 is made by punching out a lithium sheet, and is crimped onto the negative electrode current collector 2.

4 is a positive electrode can made by SVS, which also serves as a positive electrode cape.

5 is the above-mentioned positive electrode. 7 is a separator made of a nonwoven fabric made of polypropylene, and 8 is a gasket mainly made of polypropylene. The electrolyte solution used was a non-aqueous solution prepared by dissolving 1 mol/L of Lieμ04 in a 2≦1 mixed solvent of PC and DMIH. The size of the battery is 11.6 mm in outer diameter and 50 mm in total thickness.

In such a battery configuration, various daily values and 8-
Created a battery with value. 7. Connect these batteries to an external load.
After discharging for 65 s with a constant resistance of 5 RΩ, switching to a light load of 2 MΩ, and then pulse discharging for 2 seconds at a low temperature of -10°C with a load of 2 RΩ, the final voltage E1 was measured. The results are shown in FIGS. 2 and 5.

As is clear from the figure, E has a maximum value for days, values, and 8-values, and αB≦8, 8-≦
It can be seen that El is high at 1.2.

Example 2 A cross-sectional view of the battery of this practical example is shown in FIG. 15 is a positive electrode, which is made of 85% by weight of electrolytic manganese dioxide heated at 400°C for 2 hours, 11% by weight of graphite and acetylene black as a conductive agent, 1% by weight of fluororesin as a binder, and 4% by weight of fluororesin as a binder and gold. Mix well and hole diameter: 2.5
The pellets were pressurized at t/- and made into pellets (vk1 & 7111). 16 is a negative electrode, a separator consisting of a 5trs negative electrode current collector 12 punched out of a lithium sheet with a diameter of 1511cm and a BUEL negative electrode can 11 to which it is welded, and a 18Fi polypropylene gasket. . The electrolyte was a 1=1 mixed solvent of PO and DME with 1 mol/L of Li OIt Oa.
A flj solution was used. The size of the battery is outer diameter 2α
6ms and height L6111.

In such a battery configuration, by adjusting the positive electrode capacity, negative electrode capacity and electrolyte amount, various 8+ values and day-
Created a battery with value. Connect these batteries to an external load of 15
52fiAI with a constant resistance of RΩ [After discharging and switching to a light load of 2MΩ, at a low temperature of -10℃, with a load of 500Ω
Final voltage E when pulse discharged for seconds! was measured. The results are shown in Figures 5 and 6.

As is clear from the figure, m snow is l1lL8≦8+.

It shows a high value in the range of F3-≦t5, especially α9
It can be seen that it has a large shrimp value in ≦8-≦1.2.

Example 5 As an electrolyte, LiBF4 was added to a 3:1:1 mixed solvent of r-butyrolactone, dioxolane, and tetrahydrofuran.
A battery prepared in the same manner as in Example 1 was subjected to the same discharge test as in Example 1, except that a 1 mol/L solution was used. In this case as well, the relationship between %11, 8+ value, and S- value showed almost the same tendency as in Example 1.

Example 4 As a positive electrode, a pellet was used which was prepared by mixing copper oxide Cu0B7 as an active material, 10% by weight of graphite as a conductive agent, and 3% by weight of a fluororesin as a binder, and press-molding the mixture at 2t/-. In other respects, the trends of %IC1, 8+ value, and B- value were similar in batteries made in the same manner as in Example 1.

As described in detail above, the present invention provides an active material 1 for a positive electrode or a negative electrode.
By regulating the s value defined as the amount of electrolyte [μL] per sAHJ, a non-aqueous electrolyte battery with excellent discharge characteristics, particularly low-temperature heavy load characteristics at the end of discharge, is provided.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the battery implemented in Example 1. FIG. 2 is a graph showing the 8+ value and discharge characteristics of the Fe8B positive electrode, and FIG. 3 is a graph showing the relationship between the negative electrode value and the discharge characteristics. FIG. 4 is a cross-sectional view of the battery implemented in Example 2. FIG. 5 is a graph showing the 8+ value and discharge characteristics of the MnO2 positive electrode, and FIG. 6 is a graph showing the relationship between the S- value and discharge characteristics of the negative electrode. 1.11... Negative electrode can 5,15... Positive electrode 2.
12... Negative electrode current collector 6... Positive electrode pedestal 5
．． 13... Negative electrode lithium 7.17... Separator 4.14... Positive electrode can 8
．． 18...Applicant for gaskets and above Daini Seikosha Co., Ltd. @1 Figure S+II! /117AH7 14al Figure 5! h II/alH1

Claims (3)

[Claims] (1) Consisting of at least a positive electrode, a negative electrode containing lithium as the main active material, and a nonaqueous electrolyte, the total amount of electrolyte (in μm)
and the positive electrode tf have a B value (pi1mH) defined as the ratio of the active material capacity (inertumH unit) of the negative electrode 2: α8≦B+≦t5 and α8≦8−≦t2 (here, B- is the S value of the negative electrode, and S+ is the S value of the positive electrode. (2) The positive electrode uses iron disulfide as a living material, and the electrolyte is a nonaqueous electrolyte in which lithium perchlorate is dissolved in a mixed solvent of propylene carbonate (hereinafter abbreviated as PC) and dimethoxyethane (hereinafter abbreviated as DMiC). , 800 million (8+
) and negative electrode 8 value (day -) are both α80 or more t, 10
Claim No. 1 characterized in that it is controlled as follows (
1) The non-aqueous electrolyte battery described in section 1). (3) The life substance of the positive electrode is manganese dioxide, and the electrolyte is PA and DMI! ! Lithium perchlorate L in a mixed solvent of
It is a nonaqueous electrolyte in which i0J104 is dissolved, and the 8 value of the positive electrode is α80≦8+≦t30, and the S value of the negative electrode is 190≦
The non-aqueous electrolyte battery according to claim 1, wherein the non-aqueous electrolyte battery is regulated to 8-≦L20.