JP3177257B2 - Non-aqueous electrolyte secondary battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lithium alloy.
The present invention relates to a non-aqueous electrolyte secondary battery including a negative electrode and a positive electrode using manganese dioxide, molybdenum trioxide, vanadium pentoxide, titanium sulfide, or the like as an active material, and particularly relates to improvement of the negative electrode.

[0002]

2. Description of the Related Art This kind of battery has a problem that the charge / discharge cycle is extremely short because lithium, which is a negative electrode active material, precipitates in a dendritic manner on the surface of the negative electrode during charging and contacts the positive electrode, causing an internal short circuit. was there.

[0003] This is because, when the negative electrode is lithium alone, when the lithium is ionized and eluted by the discharge, the surface of the negative electrode becomes uneven, and during the subsequent charging, the lithium is intensively electrodeposited on the protruding portions and dendrites. Because it grows up.

As a countermeasure, it has been proposed that the negative electrode is made of a lithium alloy. This is because, when the negative electrode is a lithium alloy, the lithium is restored to form an alloy with the metal serving as the base of the negative electrode during charging, so that there is an advantage that the dendritic growth of lithium is suppressed.

Japanese Patent Application Laid-Open No. 61-158665 discloses a method in which a negative electrode is composed of a lithium alloy, a conductive agent and a binder.

The conductive agent is disclosed in Japanese Patent Application Laid-Open No. 1-276563.
As disclosed in Japanese Unexamined Patent Publication, it was thought that the larger the specific surface area, the higher the conductivity of the electrode and the better the charge / discharge characteristics.

However, as the specific surface area increases, the amount of oil absorption also increases, so that the swelling of the negative electrode increases after immersion in the electrolytic solution and further after charging and discharging, and the cycle characteristics have not been sufficient.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a non-aqueous electrolyte secondary battery, in particular, to suppress a change in volume due to charge and discharge and swelling of a negative electrode made of a lithium alloy, and to improve charge and discharge cycle characteristics. And

[0009]

The present invention provides a positive electrode, a lithium battery,
Powder with a specific surface area of 5 to 50 m ² / g
Consisting of conductive agent consisting of olefin resin and binder
Non-aqueous electrolyte secondary battery comprising a negative electrode to be used and a non-aqueous electrolyte
A pond, wherein the lithium alloy is lithium and aluminum
It is an alloy of chromium and manganese. Soshi
The olefin resin is polyethylene or polypropylene
It is characterized by being pyrene.

[0010]

When the specific surface area of the conductive agent is increased, the conductivity is increased, but the oil absorption is also increased. Therefore, the negative electrode expands, the adhesion between the negative electrode active material and the conductive agent is deteriorated, and the conductivity decreases.
When the electrolyte was dropped or the electrolyte was absorbed by the conductive agent, the amount of the electrolyte in the separator was reduced, the resistance was increased, and the cycle characteristics were not satisfactory.

Therefore, in the present invention, the conductivity and the cycle characteristics
To satisfy both, the lithium alloy and the specific surface area are 5
Conductive agent composed of graphite powder is 50 m ² / g and olefins
Negative electrode composed of a binder resin
The lithium alloy is lithium, aluminum and manganese
Improved cycle characteristics by using an alloy with
ing.

[0012]

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following is a reference example for assisting understanding of the present invention.
The embodiment of the present invention will be described in detail.

FIG . 1 is a longitudinal sectional view of a flat nonaqueous electrolyte secondary battery as one embodiment of the present invention.

Reference numeral 1 denotes a negative electrode made of a lithium alloy according to the gist of the present invention, which is pressed to a negative electrode current collector 3 fixed to the inner bottom surface of a negative electrode can 2. Reference numeral 4 denotes a positive electrode, which is obtained by molding a mixture of manganese oxide as an active material, acetylene black as a conductive agent, and a fluororesin as a binder in a weight ratio of 80:10:10, It is pressed against the inner bottom surface of the positive electrode can 5. Although a conductive paste is applied to the inner bottom surface of the positive electrode can 5 to enhance the current collecting effect, a current collector may be used. Reference numeral 6 denotes a separator made of a polypropylene non-woven fabric.
A non-aqueous electrolyte obtained by dissolving 1 mol / l of lithium perchlorate in an equal volume mixed solvent of carbonate and 1,2-dimethoxyethane is impregnated. Reference numeral 7 denotes an insulating packing for electrically insulating the positive and negative electrode cans. The battery dimensions are 25 mm in diameter and 3.0 mm in thickness.
It is.

Next, an example of forming a negative electrode will be described in detail. next
Although specific numerical values are those of Reference Example 1, the present invention
In the case of the example, the lithium-aluminum alloy is replaced with lithium-
It may be used instead of the aluminum-manganese alloy. Reference Example 1 As an anode, lithium and aluminum were mixed at a molar ratio of 1: 1 and reacted at 800 ° C. to produce an alloy powder obtained by pulverizing a lithium-aluminum alloy,
A mixture obtained by mixing graphite powder as a conductive agent and a polyolefin-based resin as a binder in a weight ratio of 90: 8: 2 was 1.5 t / cm ^2.
A lithium alloy plate having a diameter of 20 mm and a thickness of 1.0 mm was used. Table 1 shows the specific surface area of the used graphite powder and the battery number.

[0017]

[Table 1]

The above reference batteries (1) to (8) and comparative battery (A)
A charge / discharge test was performed for (D) to (D), and the results are shown in FIG. The charge / discharge conditions were a charge / discharge current of 2 mA, a charge / discharge time of 6 hours, and a battery that reached 2 V within the discharge time as its life.

As is apparent from FIG. 2, the cycle characteristics are excellent when the specific surface area of the conductive agent is 1 to 200 m ² / g, preferably 5 to 50 m ² / g.

[ Example ] An aluminum plate to which 1% by weight of manganese was added as a negative electrode was electrochemically alloyed with lithium in a 1,3-dioxolane solution in which 1 mol / l of LiClO ₄ was dissolved.
A mixture obtained by mixing graphite powder as a conductive agent and a polyolefin-based resin as a binder at a weight ratio of 90: 8: 2 to an alloy powder prepared by pulverizing an aluminum-manganese alloy was added to 1.5.
A battery was fabricated in the same manner as in Reference Example 1, except that a lithium alloy plate having a diameter of 20 mm and a thickness of 1.0 mm was formed by pressure molding at a pressure of t / cm ² . Table 2 shows the specific surface area of the used graphite powder and the battery number.

[0021]

[Table 2]

The above batteries (1) to (4) of the present invention and reference battery (9)
-(12) and Comparative batteries (E)-(H) were subjected to a charge / discharge test under the same conditions as in Reference Example 1, and the results are shown in FIG.

FIG. 3 shows that the specific surface area of the conductive agent is 5 to 50 m ^2.
/ G dramatically improves cycle characteristics
You can see that it is doing.

Also, lithium-manganese to which a small amount of manganese is added
By using an aluminum-manganese alloy negative electrode,
It can be seen from Tables 1 and 2 that the cycle characteristics are further improved as compared with the lithium-aluminum alloy negative electrode not added.

Reference Example 2 An aluminum plate to which 1% by weight of chromium was added as a negative electrode was electrochemically alloyed with lithium in a 1,3-dioxolane solution in which 1 mol / l of LiClO ₄ was dissolved. 1.5 t of a mixture obtained by mixing graphite powder as a conductive agent and a polyolefin-based resin as a binder at a weight ratio of 90: 8: 2 to an alloy powder prepared by pulverizing an aluminum-chromium alloy.
A battery was fabricated in the same manner as in Reference Example 1 except that a lithium alloy plate having a diameter of 20 mm and a thickness of 1.0 mm was formed by pressure molding at a pressure of / cm ² . Table 3 shows the specific surface area of the used graphite powder and the battery number.

[0026]

[Table 3]

The above reference batteries (13) to (20) and comparative batteries
A charge / discharge test was performed for (I) to (L), and the results were shown in FIG.
And Table 3.

FIG. 4 shows that the specific surface area of the conductive agent is 1 to 200 m ² /
g, preferably 5 to 50 m ² / g.

Here, in Tables 1 to 3, the ratio of the conductive agent is shown.
The cycle of each battery when the surface area is 5 to 50 m ² / g
Compare the number of files. As a result, a conductive agent with the same specific surface area is used.
In this case, the batteries (1) to (4) of the present invention correspond to the reference batteries (2) to (5) and
Cycle characteristics are superior to those of reference batteries (14) to (17).
You can see that This is because lithium-aluminum
Due to the use of an alloy consisting of
it is conceivable that.

In the present embodiment, the negative electrode was prepared by mixing a lithium alloy powder together with a conductive agent and a binder and press-molding the mixture. However, the base metal, the conductive agent and the binder were mixed and added. The same effect can be obtained by forming by alloying with lithium after pressing.

[0031]

[0032]

[0033]

The present invention can be applied to a solid electrolyte secondary battery.

[0035]

As described above in detail, the present invention relates to a positive electrode
And black having a specific surface area of 5 to 50 m ² / g with a lithium alloy
Lead powder conductive agent and olefin resin binder
Non-aqueous electrolysis comprising a negative electrode composed of
A liquid secondary battery, wherein the lithium alloy is lithium
Using an alloy of aluminum, manganese,
High conductivity, no change in electrode shape, cycle
It is possible to provide non-aqueous electrolyte secondary batteries with excellent characteristics.
Therefore , its industrial value is extremely large.

[Brief description of the drawings]

FIG. 1 is a half sectional view of a battery of the present invention.

FIG. 2 is a comparison diagram of charge / discharge cycle characteristics of a reference battery and a comparative battery.

FIG. 3 is a comparison diagram of charge / discharge cycle characteristics of the battery of the present invention, a reference battery, and a comparative battery .

FIG. 4 is a comparison diagram of charge / discharge cycle characteristics of a reference battery and a comparative battery.

[Explanation of symbols]

 Reference Signs List 1 negative electrode 2 negative electrode can 3 negative electrode current collector 4 positive electrode 5 positive electrode can 6 separator 7 insulating packing

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-276563 (JP, A) JP-A-1-209662 (JP, A) JP-A-64-6367 (JP, A) JP-A-63-63 174275 (JP, A) JP-A-1-248469 (JP, A) JP-A-1-298645 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04M 4/02-4 / 04 H04M 4/36-4/62

Claims (2)

(57) [Claims] A positive electrode, a lithium alloy and a specific surface area of 5 to 5.
Conductive agent consisting of graphite powder of 50m ² / g and olefin
And a non-aqueous electrolyte
A non-aqueous electrolyte secondary battery comprising:
The alloy is an alloy of lithium, aluminum and manganese
A non-aqueous electrolyte secondary battery characterized by the following. 2. The method according to claim 1, wherein the olefin resin is polyethylene or
2. Polypropylene is polypropylene.
Non-aqueous electrolyte secondary battery.