JPH03182059A - Secondary battery with non-aqueous electrolytic solution - Google Patents

Abstract

PURPOSE:To enhance the cycle characteristic of a battery, in which a neg. electrode is formed through shortcircuiting of a metal Li plate to a base metal plate, by making these base metal plate and metal Li plate in respective specified forms. CONSTITUTION:A battery concerned is composed of a pos. electrode 1 consisting of rechargeable active substance, a separator 3 incl. non-aqueous electrolytic solution, a base metal plate 9 consisting for ex. of Al, and a Li plate 10. The base metal plate 9 is shortcircuited to the Li plate 10 via the electrolyte to form a neg. electrode consisting of Li-Al alloy, while the base metal plate 9 is formed non-porous. Accordingly the capacity is large compared with the porous form, and the amount of initially being turned into alloy is large, and there is no edge effect. Also there is no Li locally. The Li plate 10 is porous to provide easy permeation of electrolyte. This allows achievement of a negative electrode which has large vol. energy density and has a less Li missing.

Description

[Detailed Description of the Invention] The present invention comprises a positive electrode made of a rechargeable active material such as molybdenum dioxide, vanadium pentoxide, manganese dioxide, titanium sulfide, etc., and lithium as the active material. The present invention relates to a non-aqueous electrolyte secondary battery including a negative electrode and a non-aqueous electrolyte.

The problem with this type of battery is that during charging, lithium, which is the negative electrode active material, grows like a tree on the surface of the negative electrode and comes into contact with the positive electrode, causing an internal short circuit, or it precipitates in a motu-like shape and falls off. This is because the charge/discharge cycle is extremely short.

Therefore, as shown in Japanese Unexamined Patent Publication No. 52-5423, it has been proposed that the negative electrode be made of a lithium-aluminum alloy.

This is because in the case of lithium alone, when lithium is ionized and eluted during discharge, the negative electrode surface becomes uneven, and during subsequent charging, lithium is deposited intensively on the protrusions and grows in a dendritic shape. On the other hand, in the case of a lithium-aluminum alloy, lithium restores itself to form an alloy with aluminum, which serves as the base of the negative electrode, during charging, so that the dendritic growth of lithium is suppressed, which is an advantage.

By the way, as a method for manufacturing the above alloy,
As shown in No. 46947, the electrochemically alloyed material has good properties. However, when creating the alloy as described above, it is difficult to create a large amount of the alloy at once outside the battery due to the process.

Considering this, Japanese Patent Application Laid-Open No. 50-195337
As shown in Japanese Patent Application Laid-Open No. 61-208748, a method has been proposed in which a base metal plate and a lithium plate are brought into contact with each other in the presence of an electrolyte in a battery to form an alloy.

However, when the lithium plate and the base metal plate are brought into complete contact, the electrolyte becomes difficult to penetrate between the lithium plate and the base metal plate, so that alloying does not proceed.

Therefore, in order to allow the electrolyte to easily penetrate between the base metal plate and the lithium plate, a battery using a base metal plate with holes formed therein is proposed, as shown in Japanese Patent Application Laid-Open No. 61-46947. Proposed.

However, in the conventional structure described above, the weight of the base metal plate is reduced by the amount of holes, compared to one in which holes are not formed in the base metal plate, so the amount of alloying initially is reduced. It becomes less. For this reason, the volumetric energy density of the lithium alloy decreases, and the cycle characteristics deteriorate. In addition, when holes are formed in the base metal plate, lithium is concentrated and reacts at the edges of the holes due to the edge effect. For this reason, lithium is missing at the pore edges, which also causes a problem in that the cycle characteristics deteriorate.

The present invention has been made in view of the current situation, and it is an object of the present invention to provide a non-aqueous electrolyte secondary battery that can eliminate the above-mentioned drawbacks and dramatically improve cycle characteristics.

In order to achieve the above-mentioned object, the present invention for i n In the non-aqueous electrolyte secondary battery having a negative electrode made of an alloy electrochemically alloyed by Features.

With the above configuration, since no holes are formed in the base metal plate, the amount of alloying initially increases compared to a case where holes are formed in the base metal plate. Therefore, the volumetric energy density of the lithium alloy increases.

In addition, if no holes are formed in the base metal plate, no edge effect will occur, so lithium will not concentrate in one part and react, but will react uniformly over the entire surface.

Therefore, no shortage of lithium occurs.

Furthermore, since holes are formed in the lithium plate, it is possible to easily infiltrate the electrolyte between the lithium plate and the base metal plate.

Embodiments of the present invention will be described below with reference to FIGS. 1 to 4.

[Example 1] As shown in FIG. 1, a negative electrode 2 made of a lithium-aluminum alloy is crimped onto the inner surface of a negative electrode current collector 7, and this negative electrode current collector 7 is made of stainless steel and has a substantially U-shaped cross section. is fixed to the inner bottom surface of the negative electrode can 5. The peripheral end of the negative electrode can 5 is fixed inside an insulating backing 8 made of polypropylene, and the outer periphery of the insulating backing 8 is covered with a positive electrode made of stainless steel and having a substantially U-shaped cross section in the opposite direction to the negative electrode can 5. Can 4 is fixed. A positive electrode current collector 6 is fixed to the inner bottom surface of the positive electrode can 4, and a positive electrode 1 is fixed to the inner surface of this positive electrode current collector 6. This positive electrode 1 and the negative electrode 2
A separator 3 made of a polypropylene porous membrane impregnated with a non-aqueous electrolyte is interposed between the two. In addition, as the above-mentioned non-aqueous electrolyte, propylene carbonate and 1.2
- Lithium perchlorate dissolved in a mixed solvent with dimethoxyethane at a ratio of 1 mol/l is used. Also,
The battery dimensions are 24.0+m in diameter and 3.0m in thickness.

By the way, the non-aqueous electrolyte secondary battery having the above structure was produced as follows.

First, the positive electrode l is created as follows.

After adding 10 parts by weight of acetylene blank as a conductive agent and 10 parts by weight of fluorine resin powder as a binder to 80 parts of manganese dioxide as an active material and thoroughly mixing the mixture, this positive electrode mixture was added. Manufactured by pressure molding.

In parallel with this, as shown in FIG. 3, sheet-like aluminum and lithium are punched out to predetermined dimensions to produce an aluminum plate 9 and a lithium plate 10, and holes 12 are formed in the lithium plate 10. In addition, the porosity in this case [
(Total area of pores/total area) X100) is 30%
It is.

Thereafter, as shown in FIG. 2, an aluminum plate 9, a lithium plate 10, a separator 3, and a positive electrode 1 are placed in the space formed by the positive electrode can 4 and the negative electrode 5 in this order from the negative electrode 5 side. Attach. Thereafter, the spare battery thus produced was left for one week, and a battery was produced by alloying aluminum and lithium.

The battery thus produced is hereinafter referred to as (A1) battery.

[Examples ■～■]

As shown in Table 1 below, a battery was produced in the same manner as in Example I above, except that the porosity of the lithium plate 10 was changed.

The batteries produced in this way are shown below (A2> Battery ~ (A6 ) It is called a battery.

Table 1 [Comparison rows I to ■] Except that no holes were formed in the lithium plate 10 and holes were formed in the aluminum plate 9 so as to have the porosity shown in Table 2 below,
A battery was produced in the same manner as in Example I above.

The batteries produced in this way are shown below (xl〉battery~(
X6) It is called a battery.

Table 2 [Experiment] The cycle characteristics of the (A1) to (A6) batteries of the present invention and the (X+) to (X&) batteries of the comparative examples were investigated, and the results are shown in FIG. The experimental conditions were to charge for 6 hours at a charging current of 3 mA and then discharge for 6 hours at a discharging current of 3 mA, and the battery life was determined to be the end of the battery life when the voltage reached 2 V within the discharge time.

It is clear from Figure 4 that (A1) battery ~ (A,) battery is (
It is recognized that the cycle characteristics are improved compared to the batteries Xl) to (X6).

In particular, the (A1) battery has a porosity of 10 to 50%.

The cycle characteristics of the (A3) battery to (A,) battery are dramatically improved. Therefore, the porosity is 10-50%
It is desirable that it be within the range of .

Although aluminum is used as the base metal in the above examples, it is not limited to this, and lead, indium, bismuth, tin, potassium, silicon, boron, cadmium, magnesium, zinc may also be used. It may also be aluminum or an alloy of the above metals. Furthermore, manganese is included in the base metal.

4゜ Chromium, iron, silicon, tungsten, molybdenum.

Cobalt, nickel, zirconium, magnesium, titanium, and vanadium may be added.

As explained above, according to the present invention, the volumetric energy density of the lithium alloy increases and the loss of lithium can be prevented, which improves the cycle characteristics of the non-aqueous electrolyte secondary battery. can be significantly improved.

Furthermore, since the electrolytic solution can be easily infiltrated between the lithium plate and the base metal plate, alloying can be performed within the battery, and productivity can be improved.

[Brief explanation of drawings]

FIG. 1 is a half-sectional view of the non-aqueous electrolyte secondary battery of the present invention, and FIG.
3 is a perspective view of a lithium plate and an aluminum plate used for manufacturing the non-aqueous electrolyte secondary battery of the present invention, and FIG. 4 is a half-sectional view showing the manufacturing process of the above battery. ) battery ~ (A6) battery and comparative example (X+) battery ~ (X,
) is a graph showing the cycle characteristics of the battery. 1...Positive electrode, 2...Negative electrode, 3...Separator, 9
...Aluminum plate, 10...Lithium plate.

Claims (1)

[Claims] (1) A positive electrode consisting of a rechargeable active material, a nonaqueous electrolyte, and an alloy electrochemically alloyed by shorting a base metal plate and a lithium plate in the presence of the nonaqueous electrolyte. A non-aqueous electrolyte secondary battery having a negative electrode comprising: the lithium plate having a perforated shape, and the base metal plate having a non-porous shape.