JPH0963650A - Nonaqueous secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an internal short-circuiting and provide a nonaqueous secondary battery excellent in yield and work efficiency by equipping this with wound body where a negative electrode and a positive electrode are wound through a separator, and a carbon rod at the center of the roll. SOLUTION: A positive electrode 4, which has a positive electrode lead 5, and a negative electrode 6, which has a negative electrode lead 7, are arranged to face each other across a separator 8, being wound in spiral shape to form a wound body. The wound body is inserted into a battery can 3, with the positive electrode lead 5 upward and the negative electrode lead 7 downward, and the negative electrode lead 7, to the bottom of the battery can 3, and the positive electrode lead 5, to a positive electrode cover 1 fitted with a relief valve, are spot-welded each, and the battery can 3 is calked with the positive electrode cover 1 fitted with a relief valve, and is sealed with a packing. A carbon rod 9 is inserted into the center of the wound body, and it is electrically connected to the negative electrode lead 7. Moreover, the wound body and the carbon rod 8 are soaked in electrolyte. Hereby, a nonaqueous secondary battery good in yield and work efficiency and inexpensive can be obtained.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a non-aqueous secondary battery. More specifically, the present invention relates to a non-aqueous secondary battery in which a carbon rod for preventing collapse of winding is provided at the center of a wound body composed of a positive electrode and a negative electrode wound with a separator interposed therebetween.

[0002]

2. Description of the Related Art With the miniaturization and weight reduction of electronic and information devices such as laptop computers, video cameras and mobile phones, secondary batteries for driving them have been drawing attention as important parts. In particular, a secondary battery using an alkali metal such as lithium is lightweight and has a high energy density, and thus is regarded as a promising power source for driving.

However, when lithium metal alone is used for the negative electrode, dendrites (dendritic crystals) are formed on the surface of the negative electrode due to repeated charge and discharge (dissolution-precipitation of lithium metal).
Will be generated and will grow. As a result, there is a problem that when the dendrite further grows and penetrates the separator and contacts the positive electrode, a short circuit inside the battery is induced. Further, there is a problem that the cycle life becomes short due to the formation of the passivation film due to the reaction between the lithium metal and the electrolytic solution.

Therefore, when a lithium alloy such as lithium-aluminum or lithium-tin is used for the negative electrode of the secondary battery instead of lithium metal, dendrite is generated and the electrolytic solution is formed, as compared with the case where only lithium metal is used. It was found that the passivation reaction was suppressed and the charge / discharge cycle characteristics were improved. However, even if the alloy is used, dendrite generation is not completely eliminated, and there is a considerable possibility of short circuit inside the battery. Further, since the expansion and contraction of the lithium alloy repeated with charge and discharge causes the lithium alloy to become finer, there is a problem that the energy density is lowered.

In recent years, instead of utilizing lithium metal or its alloy for the negative electrode, a lithium-containing oxide capable of electrochemically transferring lithium ions in and out of the positive electrode (for example,
By using LiCoO ₂ ) and a carbon material for the negative electrode, the dendrite formation that occurs when using lithium metal or its alloy does not occur in principle, and there is no problem of short circuit inside the battery and good cycle characteristics. High energy density lithium ion secondary batteries have been put to practical use.

Known lithium ion secondary batteries have various shapes such as a cylindrical shape and a coin shape. Among them, the cylindrical secondary battery, the sheet-shaped positive electrode and the negative electrode sandwiching the separator, at the center of the spirally wound body, insert a metal pin for collapse prevention, It is manufactured by inserting it into a battery can, impregnating it with an electrolytic solution, and caulking it with a lid.

[0007]

However, since this pin may be immersed in an electrolytic solution which is an organic substance and may be in electrical contact with the negative electrode, usable materials are limited. It was For example, JP-A-6-19613
No. 8 proposes a pin made of a metal pipe.
However, this metal pipe is expensive and not only poor in processability, but also may cause breakage of the separator when inserted into the winding body, misalignment or collapse of the winding body,
There was a possibility of causing an internal short circuit and further lowering the yield.

Further, when manufacturing the battery as described above,
Since the assembly is completed in the discharged state, it must be charged after assembly. In this charging process, lithium in the positive electrode is doped between the layers of the carbon material in the negative electrode. On the contrary, in the discharging process, lithium between layers is dedoped and returns to the positive electrode. However, the dedoping amount of the first doping of the carbon material with respect to the doping amount of lithium does not become 100%, and several% remains in the carbon material and becomes irreversible capacity because it does not participate in the subsequent charge / discharge cycle. As described above, the decrease in the amount of movable lithium ions in the battery causes the subsequent decrease in the battery capacity.

Therefore, as a method for solving this problem,
There is a method of additionally filling a positive electrode material corresponding to the first irreversible capacity of the carbon material or preliminarily doping lithium into the negative electrode material. However, there is a problem that the energy density is reduced by the amount of extra lithium. For example, a secondary battery in which metallic lithium is electrically connected to components of the negative electrode other than the negative electrode active material (JP-A-5-242911), or the negative electrode and lithium metal are electrically connected via a nickel wire. A secondary battery (JP-A-5-251111) has been proposed.

However, since the highly reactive lithium metal is used, the above method has a problem in that the safety in the manufacturing process and the manufacturing process are complicated. The present invention has been made in view of the above problems, and an object of the present invention is to provide a non-aqueous secondary battery that has good workability and yield, is inexpensive, and has a high capacity.

[0011]

Thus, according to the present invention, there is provided a wound body formed by winding a negative electrode and a positive electrode via a separator, and a carbon rod in the center of the wound body. A non-aqueous secondary battery is provided. One of the features of the present invention is that the carbon rod is used for preventing the collapse of the wound body. Therefore, lubricity with the wound body is high, and the separator on the innermost circumference of the wound body can be easily inserted without damaging the separator, so that the separator can be prevented from being damaged. Further, since carbon has a good workability, the yield and workability of manufacturing a secondary battery are improved. Furthermore, since carbon is an inexpensive and lightweight material, an inexpensive and lightweight non-aqueous secondary battery can be provided.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The carbon rod used in the present invention may have, for example, a conical shape, a truncated cone shape, a cylindrical shape, a prismatic shape, a cylindrical shape, and the like. It may have a groove. The maximum dimension of the carbon rod in the radial direction is preferably approximately the same as the diameter of the space provided in the center of the wound body from the viewpoint of preventing collapse of the winding. Further, in order to insert the carbon rod into the wound body, it is preferable that the tip of the carbon rod is thinner than the diameter of the space portion of the wound body. In addition, the presence of the groove in the length direction of the carbon rod makes it easier to inject the electrolyte solution as the non-aqueous ionic conductor, and further reduces the contact area between the separator and the carbon rod, so that an internal short circuit occurs. It is more preferable because the possibility of Further, since the electrode expands and contracts by repeating charging and discharging, it is more preferable to use a carbon rod having a groove to prevent the electrode from expanding because it can absorb the expansion of the electrode.

As the material of the carbon rod, a carbon material that can be used for the negative electrode can be used. For example, pyrolytic carbon, pyrolytic carbon in the presence of a catalyst, carbon calcined from pitch, coke, tar, etc., carbon obtained by calcining an organic polymer compound such as cellulose, phenol resin, furan resin, or glassy carbon. Examples of the graphite include carbonaceous materials, carbon fibers, activated carbon, and the like. The material of the carbon rod does not necessarily have to be the same as the carbon material that can be used for the negative electrode, but the same material is more preferable.

In the present invention, the carbon rod is preferably provided in a state of being electrically connected to the negative electrode. By doing so, the same action as the negative electrode, that is, the action of doping / dedoping lithium can be added to the carbon rod. The method for connecting the carbon rod and the negative electrode is, for example, a method in which a nickel mesh is used for the negative electrode lead of the wound body, and it is brought into contact with the carbon rod, or unevenness is provided on the nickel tab and the carbon rod is mechanically brought into contact with it. Method etc. are mentioned. There is also a method in which a recess is provided in the bottom of the battery can and a carbon rod is screwed into the recess.

A carbon rod doped with lithium corresponding to the irreversible capacity of the carbon material of the negative electrode may be used in advance. When such a carbon rod is used, it is not necessary to additionally fill the positive electrode with the positive electrode material corresponding to the irreversible capacity of the first negative electrode, and the high energy density can be achieved without reducing the amount of lithium ions that can be transferred in the battery. The non-aqueous secondary battery can be provided.

As a method for doping lithium into a carbon rod, a vapor phase method and a liquid phase method can be used. As a vapor phase method,
For example, a method of bringing vapor phase lithium into contact with a carbon rod (referred to as a contact method), a method of mixing carbon powder and lithium metal powder in an inert gas or dehumidified air atmosphere, and heating or pressurizing (powder method and There is). In the contact method, specifically, the carbon rod and the lithium metal are placed in a container such as stainless steel or quartz that can be sealed, vacuum degassing is performed, and then heat treatment is performed.
In this case, the degree of vacuum is usually about 1 × 10 ⁻⁶ Torr, and the heat treatment condition is preferably 150 to 500 ° C.

The powder method includes a heating method and a pressurizing method. The heating method is a mixture of carbon powder and lithium metal powder in a hermetically sealed container such as stainless steel or quartz (weight ratio of about 6: 1).
And heat treatment in an atmosphere of inert gas such as nitrogen gas or dehumidified air. The heating condition in this case is usually 150.
The temperature is preferably 350 ° C. However, a carbon rod having a desired shape can be obtained by subjecting the obtained powder to a molding step.

In the pressing method, the mixture contained in a container (mold) such as stainless steel is pressure-treated. The pressurizing condition in this case is preferably 10 to 20 Kbar. next,
Examples of the liquid phase method include a method of external short-circuiting or electrolysis using a carbon rod and a lithium metal as electrodes in an organic electrolytic solution containing a lithium salt. Here, the organic electrolytic solution used in the liquid phase method comprises an electrolyte salt and a solvent. Solvents include cyclic carbonates such as ethylene carbonate and butylene carbonate, chain carbonates such as dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate and dipropyl carbonate, lactones such as γ-butyrolactone, tetrahydrofuran and 2-methyltetrahydrofuran. Furans, diethyl ether, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane, 1,3-dioxolane, ethers such as dioxane, dimethyl sulfoxide, sulfolane, methylsulfolane, acetonitrile, methyl formate , Methyl acetate, methyl propionate and the like, and they can be used as a mixed solvent of one kind or two or more kinds thereof.

Further, as the electrolyte salt, for example, lithium salts such as lithium perchlorate, lithium borofluoride, lithium hexafluoroarsenate, lithium hexafluorophosphate, lithium trifluoromethanesulfonate, lithium halides and lithium aluminate chloride. And one or more of these may be mixed and used. However, in the liquid phase method, some carbon materials cannot be doped with lithium depending on the type of the electrolytic solution, and therefore the electrolytic solution must be selected. For example, a combination of a graphite-based carbon rod and a propylene carbonate-based organic electrolytic solution cannot occlude or dope lithium into the carbon rod.

The electrolysis may be performed by doping lithium in an amount corresponding to the irreversible capacity of the carbon material used for the negative electrode, and the electrolysis conditions are not limited. The positive electrode in the non-aqueous secondary battery of the present invention is
Made of a material that can electrochemically move lithium in and out,
A conductive agent, a binder, and optionally a solid electrolyte are added to the positive electrode active material.

The positive electrode active material may be any material capable of reversibly doping and dedoping lithium, and examples thereof include oxides containing lithium. More specific examples include LiCoO ₂ , LiNiO ₂ , and LiMn.
O _2, LiFeO ₂ and, in this series Li _x M _y N _z O ₂
(Where M is any one of Fe, Co, Ni, and Mn, and N represents a transition metal, preferably a Group 4B or Group 5B metal), LiMn ₂ O ₄ , and LiMn _2−x N _y O _4.
(Here, N represents a transition metal, preferably a metal of Group 4B or Group 5B), LiVO _{2, and the} like.

The conductive material is not particularly limited, and any known material can be used. For example, carbons such as carbon black (acetylene black, thermal black, channel black, etc.), graphite powder, metal powder and the like can be used. The binder is not particularly limited, and any known material can be used. For example, fluorine-based polymers such as polytetrafluoroethylene and polyvinylidene fluoride, polyolefin-based polymers such as polyethylene and polypropylene, and synthetic rubbers can be used.

The solid electrolyte is not particularly limited, and any known inorganic or organic material can be used. Examples of the inorganic solid electrolyte include a nitride of lithium, a halide, an oxyacid salt, and the like, and more specifically,
_{Li 3 N, LiI, Li 3} N-LiI-LiOH, Li
_{SiO 4 -LiI-LiOH, Li 3} PO 4 -Li 4 S
Examples include iO ₄ , phosphorus sulfide compounds, and LiSiS ₃ . Examples of organic solid electrolytes include polymers containing polyethylene oxide derivatives or derivatives, polymers containing polypropylene oxide derivatives or derivatives, and phosphoric acid ester polymers.

The mixing ratio of the conductive material and the binder to the positive electrode active material may be 5 to 50 parts by weight of the conductive material and 1 to 30 parts by weight of the binder with respect to 100 parts by weight of the active material. preferable.
When the conductive material is within this range, the resistance or polarization of the electrode is suitable, a high electric capacity can be obtained, and a practical non-aqueous secondary battery can be manufactured. Further, when the binder is within this range, a suitable binding effect can be obtained.

The positive electrode in the non-aqueous secondary battery of the present invention may be formed on the positive electrode current collector. The positive electrode current collector may be any metal that does not dissolve, aluminum,
A conductive body such as a metal foil made of titanium or the like, a metal mesh, a metal non-woven fabric or the like can be used. The thickness of this positive electrode current collector is 10 to 100 μm, and more preferably 10 to 20 μm.
μm.

Further, for example, the positive electrode can be manufactured as follows. That is, in a slurry in which a binder is dissolved or dispersed, a positive electrode active material, a conductive material, and optionally a solid electrolyte are dispersed to prepare a positive electrode paste, and this positive electrode paste is applied to one or both surfaces of a positive electrode current collector by a doctor blade. It can be prepared by coating and drying by a method or the like. In addition, after rolling this positive electrode for high density and cutting it to a certain size, a tab made of metal such as aluminum as a positive electrode lead is attached to one end of the electrode by spot welding to form a plate. Good. In the production of the positive electrode, it is preferable to perform heat treatment at a temperature around the melting point of each binder in order to improve the binding property.

The negative electrode in the non-aqueous secondary battery of the present invention is
It contains a negative electrode active material and a binder. The negative electrode active material is composed of a carbon material capable of being doped or dedoped with lithium, and includes, for example, pyrolytic carbon, pyrolytic carbon in the presence of a catalyst, pitch,
Examples thereof include carbon calcined from coke and tar, carbon obtained by calcining an organic polymer compound such as cellulose, phenol resin, and furan resin, glassy carbons, carbon fiber, and activated carbon. Further, graphite-based materials such as artificial graphite, natural graphite, expanded graphite, soil graphite and scaly graphite can also be used. Particularly, graphites having a high discharge capacity are preferable. Furthermore, the carbon material of the negative electrode does not necessarily have to be the same as the carbon material that can be used for the carbon rod, but the same material is more preferable.

The binder is not particularly limited, and any known material can be used. For example, fluorine-based polymers such as polytetrafluoroethylene and polyvinylidene fluoride, polyolefin-based polymers such as polyethylene and polypropylene, and synthetic rubbers can be used.
As the binder, a powder may be used as it is, or a powder may be dispersed in a solvent such as water or toluene to form a slurry, or a binder may be dissolved in a solvent such as N-methyl-2-pyropidone or dimethylformamide to form a slurry. Any thing can be used.

The mixing ratio of the negative electrode active material and the binder is preferably 1 to 30 parts by weight based on 100 parts by weight of the active material. When the binder is in this range, a suitable binding effect can be obtained. Further, the negative electrode in the non-aqueous secondary battery of the present invention may be formed on the negative electrode current collector. The negative electrode current collector may be any metal that does not alloy with lithium, and a conductive material such as a metal foil made of copper, nickel, iron or the like, a metal mesh or a metal non-woven fabric may be used, and the thickness is 1
0 to 100 μm is preferable, and 10 to 20 is more preferable.
μm.

Further, for example, the negative electrode can be manufactured as follows. That is, in a slurry in which a binder is dissolved or dispersed, a negative electrode active material is dispersed to prepare a negative electrode paste, and this negative electrode paste is applied to one side or both sides of a negative electrode current collector by a doctor blade method and dried. it can.
In addition, after rolling this negative electrode for high density and cutting it to a certain size, a tab or mesh made of a metal such as nickel as a negative electrode lead is attached to one end of the electrode by spot welding to form a plate. You may In the production of the negative electrode, it is preferable to perform heat treatment at a temperature around the melting point of each binder in order to improve the binding property.

Next, a non-aqueous ionic conductor is used in the non-aqueous secondary battery of the present invention. As the non-aqueous ionic conductor, for example, an organic electrolytic solution, a polymer solid electrolyte, an inorganic solid electrolyte, a molten salt or the like can be used, and among them, an organic electrolytic solution composed of an electrolyte salt and a solvent is preferably used. it can. The solvent of the organic electrolyte is mainly a cyclic carbonate such as ethylene carbonate, propylene carbonate and butylene carbonate, a chain carbonate such as dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate and dipropyl carbonate, and a lactone such as γ-butyrolactone. , Tetrahydrofuran, 2-
Furans such as methyltetrahydrofuran, diethyl ether, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane, 1,3-dioxolane, ethers such as dioxane, dimethylsulfoxide, sulfolane, methylsulfolane, acetonitrile ,
Methyl formate, methyl acetate, methyl propionate and the like can be mentioned, and they can be used as a mixed solvent of one kind or two or more kinds thereof.

Further, as the electrolyte salt, for example, lithium salts such as lithium perchlorate, lithium borofluoride, lithium hexafluoroarsenate, lithium hexafluorophosphate, lithium trifluoromethanesulfonate, lithium halides and lithium aluminate chloride. And one or more of these may be mixed and used. An electrolyte solution is prepared by dissolving the electrolyte in the solvent selected above. More specifically, an electrolytic solution in which lithium perchlorate is dissolved as an electrolyte salt in a mixed solvent of ethylene carbonate and diethyl carbonate 1: 1 (volume ratio) so as to have a concentration of 1 mol / liter can be mentioned. The solvent and electrolyte salt used when preparing the electrolytic solution are not limited to those listed above, and any known solvent can be used.

In the non-aqueous secondary battery of the present invention, a separator for holding the non-aqueous ionic conductor is provided between the positive electrode and the negative electrode. This separator also has a function of preventing a short circuit between the positive electrode and the negative electrode, and the material is not particularly limited as long as it is an insulator that is chemically stable even when it comes into contact with the non-aqueous ionic conductor and is easily processed. Specific examples include non-woven fabrics or woven fabrics such as electrically insulating synthetic resin fibers, glass fibers, and natural fibers, and molded bodies of inorganic insulating powder such as alumina. Of these, non-woven fabrics made of synthetic resins such as polyethylene and polypropylene are preferable from the viewpoint of quality stability. Some of these synthetic resin nonwoven fabric separators have a function of melting between the positive and negative electrodes by melting due to heat when the secondary battery abnormally generates heat, and these are also preferably used from the viewpoint of safety. be able to. The thickness of the separator is not particularly limited as long as it holds a necessary amount of the non-aqueous ionic conductor and has a thickness that prevents a short circuit between the positive electrode and the negative electrode, and a thickness of about 0.01 to 1 mm is usually used. Can be formed, and more preferably 0.02 to 0.05 m
m.

Next, FIG. 1 showing an example of the constitution of the non-aqueous secondary battery of the present invention will be explained. First, the positive electrode 4 having the positive electrode lead 5 and the negative electrode 6 having the negative electrode lead 7 are arranged so as to face each other with the separator 8 interposed therebetween, and are spirally wound to form a wound body. This wound body is inserted into the battery can 3 with the positive electrode lead 5 on the upper side and the negative electrode lead 7 on the lower side. The negative electrode lead 7 is on the bottom of the battery can 3 and the positive electrode lead 5 is on the positive electrode lid 1 with a safety valve. The battery can 3 is spot-welded, the battery can 3 is caulked with the positive electrode lid 1 with a safety valve, and is sealed with the packing 2. A carbon rod 9 is inserted in the center of the wound body and is electrically connected to the negative electrode lead 7. The wound body and the carbon rod 9 are immersed in an electrolytic solution (not shown).

The non-aqueous secondary battery of the present invention is characterized by comprising a wound body formed by winding a negative electrode and a positive electrode via a separator, and a carbon rod in the center of the wound body. To do. Therefore, the carbon rod for preventing winding collapse has high lubricity, and the wound body (for example,
(A spiral wound positive electrode and negative electrode wound body)
It can be inserted into and prevents internal short circuit.

Further, by preliminarily doping the carbon rod with lithium, the irreversible capacity of the negative electrode at the first time can be supplemented, and a high capacity non-aqueous secondary battery can be provided.

[0037]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Example 1 100 parts by weight of LiCoO _{2 as a} positive electrode active material, 15 parts by weight of graphite powder as a conductive material, and 10 parts by weight of polyvinylidene fluoride as a binder were dispersed in N-methyl-2-pyrrolidone. The mixture was mixed as an agent to prepare a positive electrode paste. Next, this positive electrode paste is applied to both sides of a 20 μm thick aluminum foil, which is a current collector, by a doctor blade method, dried, and rolled to a predetermined size (4
0 mm × 450 mm × 220 μm) was cut. Furthermore,
An aluminum tab of a positive electrode lead was spot welded to one end of the cut electrode to obtain a plate-shaped positive electrode.

100 parts by weight of carbon as the negative electrode active material and 10 parts by weight of polyvinylidene fluoride as the binder were mixed with N-methyl-2-pyrrolidone as a dispersant to prepare a negative electrode paste. Next, this negative electrode paste was applied onto both surfaces of a copper foil having a thickness of 18 μm as a current collector by the doctor blade method, dried, and rolled to a predetermined size (39 mm ×
It was cut to 400 mm × 135 μm). Further, a nickel tab of a negative electrode lead was spot welded to one end of the cut electrode to obtain a plate-shaped negative electrode.

A polyethylene microporous separator was sandwiched between the positive electrode and the negative electrode, arranged so as to face each other, and spirally wound to produce a wound body. Then, the wound body was placed in a battery can (diameter: 17 mm × height: 50 mm) with the positive electrode lead on the upper side and the negative electrode lead on the lower side.
mm), and the negative electrode lead was spot-welded to the bottom of the battery can and the positive electrode lead was spot-welded to the positive electrode lid with the safety valve. Further, a graphite-based carbon rod (diameter 3 mm × length 40 mm, weight 0.5 g) was inserted into the center of the wound body and attached to the negative electrode lead in a short-circuited state. After that, a fixed amount of the non-aqueous ion conductor was injected into the battery can, the packing was arranged, and the positive electrode lid with the safety valve was caulked to manufacture the non-aqueous secondary battery. Twenty such batteries were produced in the same manner.

For the non-aqueous ionic conductor, lithium perchlorate is used as an electrolyte salt in a non-aqueous solvent consisting of a mixed solvent of ethylene carbonate and diethyl carbonate 1: 1 (volume ratio) so that the concentration becomes 1 mol / liter. An electrolytic solution prepared by dissolving Regarding the obtained battery,
Charge current 500mA, upper limit voltage 4.1V, constant current constant voltage charge for 3 hours, discharge current 100mA, lower limit voltage 2.75
A constant-current discharge of V was performed, and a charge / discharge test was performed in a constant temperature bath at 25 ° C.

As a result, the discharge capacity was 600 mAh, the initial charge / discharge efficiency was 76%, and the discharge capacity after 50 cycles was 520 m.
Ah. Also, all 20 batteries evaluated were 5
There was no internal short circuit after 0 cycles. Table 1 shows the discharge capacity, the initial charge / discharge efficiency, and the number of internally short-circuited batteries.
It is considered that the internal short-circuit did not occur in Example 1 because the carbon rod having high lubricity was used as the core material for preventing the winding of the electrode winding body from being collapsed, and the separator could be inserted without damage.

Comparative Example 1 Twenty batteries were produced in the same manner as in Example 1 except that a metal pin (diameter 3 mm × length 40 mm, weight 1.5 g) was used for the carbon rod. A charge / discharge cycle test was performed on the obtained battery in the same manner as in Example 1. As a result, discharge capacity 600mA
h, the charge and discharge efficiency of the first time was 76%, which was equivalent to that of Example 1, but the discharge capacity after 50 cycles was 450 mAh, which was found to be deteriorated. Also, of the 20 batteries evaluated, 3 were internally short-circuited. When the internal short-circuited battery was disassembled, it was found that the cause of the internal short circuit was damage to the separator at the innermost circumference of the wound body or deposition of dendrite-like lithium at the contact portion between the metal pin and the negative electrode. . Table 1 shows the discharge capacity, the initial charge / discharge efficiency, and the number of internally short-circuited batteries.

In the non-aqueous electrolyte secondary battery (comparative example 1) using the metal pin for preventing the electrode from collapsing, dendride-like lithium was deposited at the contact portion between the metal pin and the negative electrode.
The amount of mobile lithium ions in the battery was reduced. Therefore, it is considered that charging / discharging was repeated with the capacity reduced and the battery capacity decreased, that is, cycle characteristics deteriorated.

Example 2 Twenty batteries were produced in the same manner as in Example 1 except that a lithium-doped graphite carbon rod was used as the carbon rod. A vapor phase method was used to dope the carbon rod with lithium. That is,
The stainless steel pipe container containing the carbon rod and metallic lithium was evacuated to 1 × 10 ^-6 Torr, and the temperature was about 50 at 400 ° C.
Lithium was doped by heating for a period of time. The surface of the obtained carbon rod changed from metallic luster to blue. For the obtained battery, in the same manner as in Example 1,
A charge / discharge cycle test was performed.

As a result, the discharge capacity was 680 mAh, the initial charge / discharge efficiency was 85%, and the discharge capacity after 50 cycles was 620 m.
With Ah, a battery having a high capacity and excellent cycle characteristics as compared with Example 1 was obtained. Also, the 20 batteries evaluated are
There was no internal short circuit after all 50 cycles. Table 1 shows the discharge capacity, initial charge and discharge efficiency, and the number of internally short-circuited batteries.
Shown in

Example 3 Twenty batteries were produced in the same manner as in Example 1 except that a graphite rod doped with lithium was used as the carbon rod. A liquid phase method was used for doping the carbon rod with lithium. That is, in a non-aqueous solvent consisting of a mixed solvent of ethylene carbonate and diethyl carbonate at a ratio of 1: 1 (volume ratio), the concentration is 1 mol /
An electrolytic solution in which lithium perchlorate was dissolved as an electrolyte salt was prepared so as to be liter. Then, a graphite carbon rod and lithium metal are immersed in this electrolyte as electrodes, and constant current electrolysis is performed at a current density of 30 mA / g for 10 minutes.
I went on time.

A charge / discharge cycle test was conducted on the obtained battery in the same manner as in Example 1. As a result, a battery having a discharge capacity of 670 mAh, an initial charge / discharge efficiency of 82%, a discharge capacity of 605 mAh after 50 cycles and a higher capacity than Example 1 and excellent cycle characteristics was obtained. Also,
All of the 20 batteries evaluated had no internal short circuit after 50 cycles. Table 1 shows the discharge capacity, the initial charge / discharge efficiency, and the number of internally short-circuited batteries.

The improvement of the initial charge and discharge efficiency of Examples 2 and 3 was made by compensating the lithium in the carbon material of the negative electrode, which becomes an irreversible capacity in the first charge and discharge, with lithium that was previously doped in the carbon rod. It is thought to be a tame. In addition, the improvement of cycle characteristics is because the dendrite-like lithium is not deposited,
It is considered that the amount of movable lithium ions in the battery did not decrease and the charging and discharging were repeated.

[0049]

[Table 1]

[0050]

EFFECTS OF THE INVENTION The non-aqueous secondary battery of the present invention comprises a wound body formed by winding a negative electrode and a positive electrode via a separator, and a carbon rod in the center of the wound body. And Therefore, the carbon rod for preventing winding collapse has high lubricity, and the wound body (for example,
(A spiral wound positive electrode and negative electrode wound body)
Since it can be inserted into a battery, and an internal short circuit can be prevented, it is possible to provide a non-aqueous secondary battery with good yield and workability.

By inserting or inserting lithium in the carbon rod in advance, lithium in the carbon material of the negative electrode, which becomes an irreversible capacity in the first charge / discharge, can be supplemented. Since lithium can be occluded even when it is in contact with, dendrite-like lithium does not precipitate and the amount of lithium ions that can move in the battery does not decrease, so the energy density does not decrease. A high-capacity non-aqueous secondary battery can be provided.

Further, since the carbon material used as the carbon rod is inexpensive and lightweight, it is possible to provide a non-aqueous secondary battery which is industrially advantageous and lightweight.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a non-aqueous secondary battery of the present invention.

[Explanation of symbols]

 1 Positive electrode lid with safety valve 2 Packing 3 Battery can 4 Positive electrode 5 Positive electrode lead 6 Negative electrode 7 Negative electrode lead 8 Separator 9 Carbon rod

Claims (4)

[Claims] 1. A non-aqueous secondary battery comprising a wound body obtained by winding a negative electrode and a positive electrode with a separator interposed between them, and a carbon rod in the center of the wound body. 2. The non-aqueous secondary battery according to claim 1, wherein the negative electrode is made of a carbon material, and the positive electrode is made of a material capable of electrochemically taking lithium in and out. 3. The non-aqueous secondary battery according to claim 1, wherein the carbon rod is electrically connected to the negative electrode. 4. The non-aqueous secondary battery according to any one of claims 1 to 3, wherein the carbon rod is a carbon rod which has been doped with lithium by a vapor phase method or a liquid phase method before the battery is manufactured. The non-aqueous secondary battery according to any one of claims 1 to 4.