JP3133420B2 - Non-aqueous electrolyte battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a spiral electrode body in which a positive electrode made of a metal oxide, sulfide or the like as an active material and a negative electrode made of a consumable metal such as lithium are wound via a separator. A non-aqueous electrolyte battery.

[0002]

2. Description of the Related Art In a spiral lithium battery, generally,
In the spiral electrode body housed in the outer can, a negative electrode is arranged on the outermost periphery of the electrode body in order to sufficiently utilize the positive electrode active material.

[0003] For this reason, even after the discharge is completed, half of the outermost negative electrode that faces only one side of the positive electrode remains unreacted and remains. Conventionally, a current collector is connected to the remaining, outermost negative electrode, and when overdischarged due to forced discharge, the negative electrode exceeding the reaction limit of the positive electrode active material moves to the opposite positive electrode surface and precipitates, There was a problem that caused an internal short.

To cope with this, the thickness of the negative electrode was made as thin as possible to reduce the amount of the negative electrode active material on the outermost periphery and to suppress the amount of lithium deposition.

[0005] However, in the method of reducing the thickness of the negative electrode, the negative electrode is easily cut in the winding step, resulting in poor productivity.
The amount of lithium deposited during overdischarge is not small. However, if the thickness of the negative electrode is further reduced, it is certain that the capacity of the negative electrode will be reduced, resulting in a significant decrease in performance.

When the positive and negative electrodes are thinned to increase the area of the electrode plate, the amount of the negative electrode deposited per unit positive electrode area decreases,
Although the discharge characteristics do not deteriorate, the facing area must be increased more than necessary because the thickness must be significantly reduced, and a large current is generated when an external short circuit occurs, the battery is overheated, and there is a concern that an internal short circuit may occur due to melting of the separator. Is done.

[0007]

Accordingly, by providing a structure for separating the negative electrode current collecting tab from the outermost negative electrode at the end of discharge, it is possible to prevent the negative electrode from moving to the positive electrode surface due to overdischarge or the like and depositing. Things.

[0008]

A strip-shaped positive electrode and a strip-shaped negative electrode made of consumable metal consumed by a discharge reaction are
A battery provided with a spiral electrode body wound around a separator and having a negative electrode positioned on the outermost periphery, wherein i) a terminal end of the positive electrode reacts only with the negative electrode inside the winding, ii) a negative electrode current collecting tab comprises: By satisfying the above-mentioned requirement that current is collected from a position one or more rounds inward from the winding end portion of the negative electrode, the negative electrode current collecting tab is separated from the negative electrode remaining on the outermost periphery at the end of discharge.

[0009]

According to the arrangement and mounting structure of the negative electrode tab of the present invention, the outermost negative electrode having only one surface facing the positive electrode is separated from the inner negative electrode at the end of discharge, and lithium is deposited on the positive electrode during overdischarge. It is to prevent that.

Of course, the use of the structure of the present invention does not cause a decrease in the discharge characteristics and eliminates the need to adjust the remaining amount of the negative electrode. Is also reduced.

By taking the position of the negative electrode tab shown in FIG. 3A, the negative electrode 1 facing the winding end portion A of the positive electrode 4 is quickly consumed by the positive electrode edge effect, and the state shown in FIG. Thus, the discharged negative electrode 1 is separated from the negative electrode 1 located at the outermost periphery of the wound electrode body.

Thus, at the end of discharge, the negative electrode on the outermost periphery of the electrode body is not in contact with the current collecting tab, so that even if overdischarge occurs, deposition of the negative electrode metal on the positive electrode facing the outermost peripheral negative electrode is eliminated. , Thereby preventing the occurrence of an internal short circuit. Therefore, the safety in the over-discharge state of the battery can be drastically improved.

The consumption speed of the negative electrode can be controlled by arranging an insulator having no ion permeability so as to cover at least the opposing portion inside the winding of the negative electrode facing the winding end of the positive electrode. Therefore, negative electrode dendride at the time of overdischarge can be prevented, and at the end of discharge, the negative electrode tab and the outermost peripheral negative electrode are cut, so that the negative electrode can be used effectively.

Further, by taking out the negative electrode tab through a portion that does not exist on the outer periphery of the spiral electrode body, in addition to the above-mentioned effects, it is possible to prevent the negative electrode tab from being bent due to vibration, breaking the separator and causing an internal short circuit.

[0015]

[Embodiment 1] An embodiment of the present invention will be described below in detail.

FIG. 1 shows a method for forming a negative electrode. Thickness 0.
To a metallic lithium 1 cut to 20 mm, 23 mm in width, and 230 mm in length, an I-shaped tab 2 made of a Ni plate having a width of 3 mm and a length of 21 mm was attached at a position 180 mm from the tip of the negative electrode, and attached with tape 3 from both sides. It was fixed in contact with lithium.

Next, FIG. 2 shows a method of forming a positive electrode. First, 890 g of manganese dioxide and 80 g of graphite are mixed with a grinder for 30 minutes. Further, trifluoroethylene was added and mixed for 10 minutes, 15 g of polyvinyl alcohol dissolved in 110 g of pure water was added and kneaded for 20 minutes,
Slurry. This is applied to the positive electrode core, dried,
Rolling and cutting, thickness 0.43mm, width 26mm,
A positive electrode 4 having a length of 230 mm was prepared. Here, a 0.1 mm-thick lath-processed plate made of SUS304 was used as the positive electrode core. The center of the positive electrode 4 was peeled off over a width of 5 mm and a length of 21 mm, and a SUS304 stainless steel plate having a length of 35 mm, a width of 3 mm, and a thickness of 0.15 mm was spot-welded thereon to form a current collecting tab 5. Glass
Covered with step 6. This positive electrode was heat-treated at 230 ° C. to remove moisture, and cooled in a dehumidified atmosphere. The positive electrode and the negative electrode were wound through a polyethylene microporous membrane separator having a width of 29 mm, and the outermost circumference was entirely covered with tape. This electrode body is referred to as W.

FIG. 3 is a cross-sectional view of the spiral electrode body W. FIG. 3A shows the state before the discharge, and FIG.

Since the positive electrode terminal portion A faces only the negative electrode on one side, the amount of the negative electrode inside the negative electrode end portion A decreases more quickly. In the spiral electrode body W of the present invention, since the current is collected from the inner side of the winding at least one turn from the end of the negative electrode winding, the negative electrode facing the positive electrode terminal does not elute at the end of discharge, and the outermost lithium Will be unable to collect current and will be safe against overdischarge.

Embodiment 2 Hereinafter, another embodiment of the present invention will be described in detail.

FIG. 4A shows a method of forming the negative electrode. Metallic lithium 1 cut to a thickness of 0.20 mm, a width of 23 mm, and a length of 230 mm was added with a width of 3 mm, a length of 21 mm, and a thickness of 0.2 mm.
A 1 mm Ni tab 2 was attached and held down with a tape 3 and then an insulating tape 8 was attached to lithium. As the tape, a polyethylene terephthalate tape having a width of 9 mm, a length of 14 mm, and a thickness of 0.06 mm was used.

The same positive electrode as that prepared in Example 1 was used.

The positive electrode and the negative electrode are wound through a polyethylene microporous membrane separator having a width of 29 mm, and an electrode body whose outermost periphery is entirely covered with a tape is designated as X.

FIG. 5 is a cross-sectional view of the spiral electrode body X, and FIGS. 5A to 5C show changes in the negative electrode accompanying discharge.

This electrode body X has the following features. i) The winding end portion A of the positive electrode reacts only with the negative electrode inside the winding. ii) Current is collected from a position one or more rounds inward from the winding end of the negative electrode. vi) An insulator having no ion permeability is arranged inside the winding of the negative electrode opposite to the end of the winding of the positive electrode so as to cover at least the opposing portion.

By taking the position of the negative electrode tab shown in FIG. Causes the changes in FIG. 5-a to FIG. 5-c in order. When the discharge proceeds by 50%, as shown in FIG. 5B, the amount of consumption of the negative electrode facing the double-sided positive electrode increases, resulting in an uneven state. In particular, the negative electrode facing the positive winding end portion is consumed at a high speed, and is in a more consumed state.

At this time, a portion without the ion-impermeable tape 8 is indicated by a dotted line, and it is shown that the portion without the tape 8 is consumed more quickly than the portion with the tape 8. Further, FIG. 5-c shows that the process has progressed to the end of discharge, and a part of the negative electrode where the tape 8 having no ion permeability is attached has been consumed by the influence of the positive electrode end. For this reason, conduction between the negative electrode current collecting tab 2 and the negative electrode lithium 1 at the outermost periphery is lost.

Therefore, even when the battery is overdischarged, the outermost lithium does not become lithium ions and does not move to the positive electrode, so that lithium dendride does not occur and battery safety is maintained.

The second embodiment is an application of the first embodiment.
By disposing an insulator having no ion permeability on the inner side surface of the winding of the negative electrode opposite to the cathode winding end portion A, the negative electrode portion on which the insulator 8 having no ion permeability is reacted only with the positive electrode outside the winding. Therefore, the positive electrode edge effect is controlled. Therefore,
Immediately before the end of the discharge, the negative electrode current collecting tab is separated from the outermost negative electrode, so that the discharge capacity is improved as compared with the first embodiment, and the discharge characteristics do not deteriorate.

Further, as shown in FIG. 4B , the tab tape 3 and the insulating tape 8 are also used,
There is no functional problem with pasting.

The insulating tape 8 is used as an obstacle made of a material having no ion permeability, and has the same effect even on a perforated sheet, woven fabric, non-woven fabric, or the like. Therefore, the present invention is not limited to the insulating tape.

Embodiment 3 Hereinafter, still another embodiment of the present invention will be described in detail.

FIG. 6 shows a method of forming the negative electrode. Thickness 0.
An insulating film 9 is placed at the end of metallic lithium 1 cut to 20 mm, 23 mm in width and 230 mm in length. Align and overlap so that only the lithium contacts. Here, the length of the L-shaped tab in contact with lithium is 5 mm out of 25 mm on a side, and the lead portion of this L-shaped tab is 20 mm from the end of lithium.
The position is 0 mm. Adhesive tape 10 on this tab
(Made of polyethylene terephthalate) to form a negative electrode.

The same positive electrode as that prepared in Example 1 was used. The positive electrode and the negative electrode are wound via a 29-mm-wide polyethylene microporous membrane separator, and Y is an electrode body whose outermost periphery is entirely covered with tape.

FIG. 7 is a cross-sectional view of the spirally wound electrode body Y, and FIGS. 7A to 7C show changes in the negative electrode accompanying discharge.

The position and structure of the negative electrode tab of the electrode body Y are i) to
v). i) The winding end portion A of the positive electrode reacts only with the negative electrode inside the winding. ii) Current is collected from a position one or more rounds inward from the winding end of the negative electrode. iii) The negative electrode current collecting tab 2 is disposed on the inner side surface of the negative electrode. iv) The negative electrode at a position inside the winding within one turn from the winding end of the negative electrode is insulated from the negative electrode current collecting tab. v) The extended end of the negative electrode current collection tab is connected to the outer can through a portion on the outer periphery of the spiral electrode body where no positive electrode exists.

The negative electrode current collecting tab does not necessarily need to have an L-shape. As shown in FIG. 8, the extended end of the negative electrode current collecting tab is directly extended in the winding direction, taken out from the negative electrode winding end portion, and collected by contact. May be.

As shown in FIG. 7B, the method of decreasing the negative electrode is characterized in that the portion of the positive electrode terminal portion with respect to the edge C is particularly fast, and the portion without the negative electrode tab tape in the middle of discharging is the portion indicated by the dotted line. If the winding end of the positive electrode is wrapped with a tape, the reaction between the boundary between the tape and the positive electrode and the opposing negative electrode becomes more intense.

Now, in this structure, since the negative electrode surface on which the insulating film and the adhesive tape are adhered cannot react with the positive electrode in the winding, the negative electrode on which the insulating film is adhered and the positive electrode on the outside thereof The amount of the positive electrode active material: the amount of the negative electrode active material becomes 1: 1. However, due to the effect of the positive electrode edge, the positive electrode is separated more quickly and reliably. As shown in part D of FIG. There is no conduction between the electrode and the outermost peripheral negative electrode, and no negative electrode dendrite is generated due to overdischarge, and safety is ensured.

If each of the above conditions i) to iv) is not satisfied, the outermost negative electrode and the negative electrode tab continue to be connected at the end of the discharge, so that it is not safe against overdischarge.

FIG. 9 is a longitudinal sectional view showing the state where the electrode body Y is inserted into the outer can. As shown in FIG. , The bending of the negative electrode tab due to vibration can be prevented, and no internal short circuit occurs.

Comparative Example 1 As a comparative example, a case where a current collecting tab is attached to lithium on the outermost periphery of an electrode body will be described.
The same positive electrode plate as in Example 1 was used, and the negative electrode had a thickness of 0.
20, a lithium band having a width of 23 mm was cut into 230 mm, and an I-shaped tab made of a Ni plate having a width of 3 mm and a length of 21 mm was attached.

The positive electrode and the negative electrode are wound up through a polyethylene microporous membrane separator having a width of 29 mm, and the electrode body entirely covered with the outermost peripheral tape is designated as Z. FIG. 10 shows a cross-sectional view of the electrode body Z.

FIG. 10A shows an electrode body before discharge, wherein 1 is a negative electrode, 2 is a negative electrode tab, 3 is a tape, and 4 is a positive electrode. The position of the negative electrode tab of the electrode body is on the negative electrode which faces only one side of the positive electrode on the outermost periphery of the electrode body, and is pulled out from that position to the bottom of the can.

FIG. 10B is a cross-sectional view of the electrode body Z at the end of discharge. The negative electrode facing both sides of the positive electrode is consumed,
It is cut off at the portion E, and the outermost lithium remains with the current collector attached. When overdischarged in this state, lithium is ionized and deposited on the positive electrode which has completely reacted with lithium. This active precipitated lithium may break the separator and cause an internal short circuit, and the spark may ignite.

These electrode bodies W to Z are φ16.5, h3
The result of assembling into a 3.5 battery and discharging 200Ω at 23 ° C. is shown in FIG. The battery of the present invention has a discharge characteristic equal to or higher than that of the conventional battery. From these results, the battery of the present invention can be manufactured with a safe battery without lowering the discharge characteristics.

[0047]

According to the present invention, the negative electrode on the outermost periphery of the spiral electrode body is insulated from the current collecting tab at the end of discharge, and the negative electrode remaining on the outermost periphery is prevented from depositing on the positive electrode during overdischarge. Furthermore, by arranging an insulator having no ion permeability over the opposing portion on the inner side of the negative electrode facing the winding end of the positive electrode, the negative electrode can be effectively used. By taking out through a portion that does not exist on the outer periphery of the electrode body, in addition to the above-described effects, it is possible to prevent the negative electrode tab from being bent due to vibration, breaking the separator and causing an internal short circuit, and its industrial value is extremely large. It is.

[Brief description of the drawings]

FIG. 1 shows a method for producing a negative electrode according to the present invention.

FIG. 2 illustrates a method for manufacturing a positive electrode.

FIG. 3a is a cross-sectional view of an electrode body W of the present invention. b is a cross-sectional view of the electrode body W at the end of discharge.

FIG. 4a shows another embodiment of the method for producing a negative electrode according to the present invention. b Another embodiment of the method for producing a negative electrode according to the present invention.

FIG. 5a is a cross-sectional view of an electrode body X of the present invention. b is a cross-sectional view of the electrode body X at 50% discharge. c It is a cross-sectional view of the electrode body X at the end of discharge.

FIG. 6 is another embodiment of the method for producing a negative electrode according to the present invention.

FIG. 7a is a cross-sectional view of an electrode body Y of the present invention. b is a transverse sectional view of the electrode body Y at 50% discharge. c is a cross-sectional view of the electrode body Y at the end of discharge.

FIG. 8 is an example of contact current collection of the electrode body of the present invention.

FIG. 9 is a longitudinal sectional view in a state where the electrode body Y of the present invention is inserted into an outer can.

10a is a cross-sectional view of a comparative electrode body Z. FIG. b is a cross-sectional view of the electrode body Z at the end of discharge.

FIG. 11 is a comparison diagram of discharge characteristics between the present invention and a comparative example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 negative electrode 2 negative electrode current collecting tab 3 tape 4 positive electrode 5 positive electrode current collecting tab 6 glass tape 7 separator 8 insulating tape 9 insulating film 10 adhesive tape W to Y electrode body of the present invention Z comparative electrode body

──────────────────────────────────────────────────続 き Continuation of the front page (56) References Japanese Utility Model 1-119161 (JP, U) Japanese Utility Model 3-69859 (JP, U) Japanese Utility Model 2-42365 (JP, U) Japanese Utility Model 1 119161 (JP, U) Hira 3-69859 (JP, U) Hira 2-42365 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 2/26 H01M 2 / 34 H01M 6/16 H01M 10/40

Claims (3)

(57) [Claims] 1. A battery provided with a spiral electrode body in which a strip-shaped positive electrode and a strip-shaped negative electrode made of a consumable metal consumed by a discharge reaction are wound via a separator, and the negative electrode is located at the outermost periphery. I) the winding end of the positive electrode reacts only with the negative electrode on the inner side of the winding; ii) the negative electrode current collecting tab collects power from a position at least one turn inside the winding from the winding end of the negative electrode; A non-aqueous electrolyte battery, which satisfies the requirements of (i) and (ii). 2. An outer can for accommodating the spiral electrode body also serves as a negative electrode terminal; iii) a negative electrode current collecting tab is arranged on an inner side surface of the negative electrode; The negative electrode at the position inside the winding is insulated from the negative electrode current collecting tab. V) The extended end of the negative electrode current collecting tab is provided on the outer periphery of the spiral electrode body through the part where the positive electrode does not exist. The non-aqueous electrolyte battery according to claim 1, wherein the battery satisfies the above requirements (iii) to (v), which are connected to a can. 3. The insulator according to claim 1, wherein an insulator having no ion permeability is disposed inside the winding of the negative electrode opposite to the end of the winding of the positive electrode so as to cover at least the opposing portion. Non-aqueous electrolyte battery.