JP2008060028A - Power storage device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power storage device which is easy to manufacture, which can be predoped homogeneously in a short time, and in which practical predoping is possible in order to realize high capacity by predoping, improvement of energy density by high voltage, and high output since a level of demand is high for high energy density and high output/high rate charging characteristics in the power storage device. <P>SOLUTION: In a nonaqueous power storage device having a positive electrode containing a positive electrode active material capable of storing and releasing lithium, a negative electrode containing a negative electrode active material capable of storing and releasing lithium, and an electrolytic solution in which lithium salt is dissolved in a nonaqueous solvent, either one of a positive electrode current collector or a negative electrode current collector has a hole to penetrate through the front and rear faces. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electricity storage device having high energy density and high output characteristics that can be manufactured based on a simple and practical pre-doping technique.

In recent years, various high energy densities related to power sources for small portable devices typified by mobile phones, midnight power storage systems, home-use distributed storage systems based on solar power generation, storage systems for electric vehicles, etc. Batteries are being developed vigorously. In particular, the lithium ion battery has a volume energy density exceeding 350 Wh / l, and is superior in reliability such as safety and cycle characteristics as compared with a lithium secondary battery using metallic lithium as a negative electrode. The market is rapidly expanding as a power source for small portable devices. The lithium ion battery uses a lithium-containing transition metal oxide typified by LiCoO ₂ or LiMn ₂ O ₄ as a positive electrode and a carbon-based material typified by graphite as a negative electrode. Currently, further increase in capacity of lithium-ion batteries is being promoted, but the increase in capacity by improving positive electrode oxide and negative electrode carbon-based materials has almost reached its limit, and it has been able to cope with high energy density from the device side. It is difficult to meet the requirements. Also, in order to operate an engine or a fuel cell with maximum efficiency in a combination of a high-efficiency engine and a power storage system (for example, a hybrid electric vehicle) or a combination of a fuel cell and a power storage system (for example, a fuel cell electric vehicle). Therefore, an operation at a constant output is essential, and in order to cope with output fluctuation or energy regeneration on the load side, high output discharge characteristics and high rate charge characteristics are required on the power storage system side. In order to meet this demand, research and development has been carried out in power storage systems to increase the output of lithium ion batteries characterized by high energy density or to increase the energy density of electric double layer capacitors characterized by high output. Yes.

On the other hand, in a power storage device such as a lithium ion battery or a capacitor, attention has been paid to a technology for increasing the capacity and voltage of the power storage device by previously supporting lithium ions on the active material (hereinafter referred to as pre-doping). For example, this pre-doping is applied to a high-capacity material such as an insoluble infusible substrate containing a polyacene-based skeleton structure described in Non-Patent Document 1, Patent Document 1, Non-Patent Document 2, Non-Patent Document 3, etc. Accordingly, as described in Non-Patent Document 4, it is possible to design an electricity storage device that fully utilizes its characteristics (high capacity), and meet the demand for higher energy density or higher output of the electricity storage device. Is possible. Pre-doping is a technology that has been practically used for a long time. For example, in Non-Patent Document 5 and Patent Document 2, lithium is pre-doped on an insoluble infusible substrate containing a polyacene skeleton structure as a negative electrode active material. A high voltage and high capacity power storage device is disclosed. Regarding pre-doping, a method of incorporating lithium in advance into an electricity storage device using a lithium-supported electrode, a method of mixing lithium metal or the like at the time of electrode formation, and the like are known, but for a simple and practical pre-doping method, an active material There is a method in which a lithium metal foil is brought into contact with an electrode that contains. This technique has a small number of electrodes and is effective for a coin type using relatively thick electrodes. However, the process is complicated in a stacked structure battery or a wound structure battery in which a plurality of thin electrodes are stacked. Or there was a problem in handling thin lithium metal, and a simple and practical pre-doping method was required.

As a method for solving this problem, Patent Document 3 includes a hole penetrating the front and back surfaces, the negative electrode active material can reversibly carry lithium, and the lithium derived from the negative electrode is disposed facing the negative electrode or the positive electrode. An organic electrolyte battery is disclosed, which is supported by electrochemical contact with lithium and has an opposing area of lithium of 40% or less of the negative electrode area. In this battery, an electrode layer is formed on a current collector provided with a through hole, and lithium metal and a negative electrode disposed in the battery are short-circuited, so that lithium ions pass through the current collector through-hole, Doped in the negative electrode. In an example of Patent Document 3, an expanded metal is used for a current collector having a through hole, an organic material using an insoluble infusible substrate containing LiCoO _{2 as} a positive electrode active material and a polyacene skeleton structure as a negative electrode active material. An electrolyte battery is disclosed, and the negative electrode active material can be easily pre-doped with lithium ions from lithium metal disposed in the battery.

Patent Document 4 discloses that the dropout of the electrode from the current collector is reduced by using a current collector having holes penetrating the front and back surfaces with a porosity of 1% to 30%. Patent Document 5 uses an insoluble infusible substrate containing a polyacene skeleton structure having a specific surface area of 1900 m ² / g as a positive electrode, an insoluble infusible substrate containing a polyacene skeleton structure as a negative electrode, and these active materials. A capacitor is disclosed which is formed on a current collector provided with a through hole and pre-doped with lithium ions from a lithium metal disposed in a battery into a negative electrode active material. Patent Document 6 discloses that by filling a hole of a current collector having a through hole, it is easy to form an electrode layer and to prevent the electrode from falling off. In the prior arts of Patent Documents 3 to 6, it is necessary to use a current collector having through holes in both the positive electrode and the negative electrode in order to allow lithium to permeate through a plurality of positive electrodes and negative electrodes and advance the pre-doping. The time required to do this is also quite long. (Patent Document 6 is left for 14 days until the end of pre-doping is confirmed).

As a simple and practical pre-doping method as described above, an electrode layer is formed on a current collector provided with a through-hole, and a lithium metal and a negative electrode arranged in the battery are short-circuited, so that lithium ions become positive and negative. A technique of passing through a through-hole of a negative electrode current collector and supporting it on an electrode active material is disclosed. However, from the viewpoint of manufacturing, there is a demand for a technique that refrains from using a current collector having a special through hole and that can be uniformly pre-doped in a shorter time. In order to pre-dope uniformly in a short time, it is practically preferable to apply lithium metal to the entire electrode surface including the active material to be pre-doped. It had problems such as difficult things.
T.A. Yamabe, M .; Fujii, S .; Mori, H .; Kinoshita, S .; Yata: Synth. Met. , 145, 31 (2004) JP 59-3806 S. Yata, Y. et al. Hato, K .; Sakurai, T .; Osaki, K .; Tanaka, T .; Yamabe: Synth. Met. , 18, 645 (1987) S. Yata, H .; Kinoshita, M .; Komori, N .; Ando, T .; Kashiwamura, T .; Harada, K .; Tanaka, T .; Yamabe: Synth. Met. 62, 153 (1994) S. Yata, Y. et al. Hato, H .; Kinoshita, N .; Ando, A .; Anekawa, T .; Hashimoto, M .; Yamaguchi, K .; Tanaka, T .; Yamabe: Synth. Met. 73, 273 (1995) Shigeru Yada, Industrial Materials, Vol. 40, no. 5, 32 (1992) JP-A-3-233860 WO98 / 33227 WO00 / 07255 WO03 / 003395 publication WO04 / 097867

  There is a high level of demand for high energy density and high output in power storage devices such as lithium ion batteries and capacitors. In order to meet this demand, it is considered that increasing the capacity by lithium pre-doping of a high-capacity material, or improving the energy density and increasing the output by increasing the voltage are essential technologies for the future development of power storage devices. The above-described pre-doping technology using a current collector with a through hole contributes to high energy density and high output in an electricity storage device, although it is necessary to use a current collector with through holes in both the positive electrode and the negative electrode. It is a thing. However, from the viewpoint of manufacturing, there is a demand for a technique that refrains from using a current collector having a special through hole and that can be uniformly pre-doped in a shorter time. In order to pre-dope uniformly in a short time, practically, a method of sticking lithium metal to the entire electrode surface including the active material to be pre-doped is preferable, but the thin lithium metal is necessary as described above, and its handling is It had problems such as difficult things. Accordingly, an object of the present invention is to provide a power storage device capable of practical pre-doping that can be applied with a pre-doping method by attaching lithium metal, can be easily manufactured, and can be uniformly pre-doped in a short time.

  As a result of conducting research while paying attention to the problems of the prior art as described above, the present inventor uses a current collector having a hole penetrating the front and back surfaces only for either the positive electrode or the negative electrode. The present inventors have found that a pre-doping method by sticking lithium metal can be applied, can be easily manufactured, and can be uniformly pre-doped in a short time, and the present invention has been completed.

  The electricity storage device according to claim 1 includes a positive electrode including a positive electrode active material capable of occluding and releasing lithium, a negative electrode including a negative electrode active material capable of occluding and releasing lithium, and an electrolytic solution obtained by dissolving a lithium salt in a non-aqueous solvent. In the non-aqueous power storage device having the above, the positive electrode current collector does not have a hole penetrating the front and back surfaces, and the negative electrode current collector has a hole penetrating the front and back surfaces.

  The electricity storage device according to claim 2 is a positive electrode including a positive electrode active material capable of occluding and releasing lithium, a negative electrode including a negative electrode active material capable of occluding and releasing lithium, and an electrolytic solution in which a lithium salt is dissolved in a non-aqueous solvent. In the non-aqueous power storage device having the above, the positive electrode current collector has a hole penetrating the front and back surfaces, and the negative electrode current collector does not have a hole penetrating the front and back surfaces.

  According to the configuration of the first or second aspect, a pre-doping method by sticking lithium metal can be applied, manufacturing is easy, and uniform pre-doping can be performed in a short time.

  The electricity storage device according to claim 3 is characterized in that the porosity of the current collector having the through-hole according to claim 1 or 2 is 10% or more and 90% or less.

  The electricity storage device of the present invention can be applied to a pre-doping method by attaching lithium metal by using a current collector having holes penetrating the front and back surfaces for either the positive electrode or the negative electrode. In addition, there is an effect that it can be pre-doped uniformly in a short time.

  An embodiment of the present invention will be described as follows.

  In the electricity storage device of the present invention, a current collector having holes penetrating the front and back surfaces is used only for either the positive electrode or the negative electrode. In the configuration described in claim 1, the positive electrode current collector does not have a hole penetrating the front and back surfaces, and the negative electrode current collector has a hole penetrating the front and back surfaces. In the configuration described in claim 2, the positive electrode current collector has a hole penetrating the front and back surfaces, and the negative electrode current collector does not have a hole penetrating the front and back surfaces.

The current collector having a hole penetrating the front and back surfaces in the present invention is described in Patent Documents 3 to 6, but includes a hole penetrating the front and back surfaces of the current collector. For example, punching, etching, etc. Examples include conductive substrates (such as punching foils, etching foils, and perforated foils) with holes penetrating the front and back surfaces, foamed conductive substrates, conductive material nets, and non-woven fabrics of conductive materials. Further, a punching foil, etching foil or perforated foil of 30 μm or less is preferable. The current collector is made of metal, carbon or the like having high electrical conductivity. For example, the electrical conductivity of the current collector is 10 ⁰ S / cm or more, which is sufficiently higher than the electrical conductivity of the electrode. It is what you have. The material of the current collector is appropriately determined depending on the voltage / output design of the electricity storage device of the present invention, the type of active material / conductive material / binder included in the electrode layer formed on the current collector, or the electrolyte. Yes, although not particularly limited, when the negative electrode current collector has a hole penetrating the front and back surfaces as described in claim 1, that is, copper is generally used as the negative electrode current collector. Thus, when the positive electrode current collector has holes penetrating the front and back surfaces, that is, the positive electrode current collector is generally aluminum.

The shape of the hole penetrating the front and back surfaces in the present invention is not particularly limited, but various shapes such as a circle, an ellipse, a rectangle, and a polygon are possible as the shape visible on the front surface or the back surface. It is possible to penetrate the current collector front and back surfaces in various shapes such as linear, curved, and three-dimensional.

The porosity of the current collector having holes penetrating the front and back surfaces in the present invention is not particularly limited, but is 10% or more and 90% or less, more preferably more than 30% and 60% or less. In the present invention, the porosity means the volume ratio of holes penetrating the front and back surfaces in the current collector volume. Specifically, the current collector area is A (cm ² ), the current collector thickness is B (cm), the current collector weight is W (g), and the current collector material When the specific gravity ρ (g / cm ³ ) is used, the porosity is “1−W / (A × B × ρ)” × 100%, and in the prior art, this is called the ratio of through-holes, porosity. There is also. This porosity is preferably set large in order to increase the speed of pre-doping or improve the uniformity of pre-doping, but if it is too large, from the viewpoint of ease of electrode layer formation on the current collector and electrode strength It is not preferable.

The width of the hole penetrating the front and back surfaces in the present invention is not particularly limited, but is preferably 1 mm or less, more preferably 0.7 mm or less, and particularly preferably 0.4 mm or less. When the width of the hole is too large, it is difficult to obtain high output load characteristics. Moreover, about a minimum, Preferably it is 0.05 mm or more, More preferably, it is 0.1 mm or more, and when too small, manufacture of an electrical power collector will become difficult. The hole width refers to the shortest distance from all points in the hole to the current collector, and twice the maximum value is defined as the hole width in the present invention. When the cross section of the hole is a circle, the maximum value of the shortest distance from the point in the hole to the current collector is the radius, and the width of the hole is twice the radius, that is, the diameter. When the cross section of the hole is rectangular, the maximum value of the shortest distance from the point in the hole to the current collector is ½ of the length of the short side, and the width of the hole is the length of the short side of the hole. When the cross section of the hole is elliptical, the maximum value of the shortest distance from the point in the hole to the current collector is the short axis radius, and the width of the hole is the short axis diameter. Further, in the case of an irregular hole, it is preferable that the width of the hole is obtained as described above in each cross section, and 80% or more thereof falls within the above range.

In the positive electrode or the negative electrode of the present invention, an electrode layer containing an active material is formed on a current collector having holes penetrating the front and back surfaces. The electrode layer is formed on both sides or one side of the current collector having a through-hole, and can also be formed in the current collector hole. The electrode layer contains an active material as a main component, and can be formed using a conductive material and a binder as necessary. The type of the binder is not particularly limited, and examples thereof include fluorine resins such as polyvinylidene fluoride and polytetrafluoroethylene, and polyolefins such as fluorine rubber, SBR, acrylic resin, polyethylene, and polypropylene. . The amount of the binder is not particularly limited, and is appropriately determined depending on the average particle diameter, shape, and the like of the active material. For example, the ratio is preferably about 1% to 30% of the weight of the active material. In addition, the type and amount of the conductive material are not particularly limited, and are appropriately determined depending on the electronic conductivity, average particle size, shape, and the like of the active material. Examples of the material include carbon black and acetylene black. Examples thereof include carbon materials such as graphite and metal materials. The amount of the conductive material is not particularly limited, and an amount necessary for obtaining the electrical conductivity of the electrode described later is added. The electrode for the electricity storage device of the present invention is formed on the current collector using a known electrode molding method such as coating molding, press molding, roll molding, etc., using the above active material, if necessary, a conductive material and a binder. And can be manufactured.

The current collector having no hole penetrating the front and back surfaces in the present invention is, for example, a foil-shaped or plate-shaped current collector generally used for conventional lithium ion batteries, capacitors, etc. Even if it has unevenness etched for the purpose of roughening the surface, it can be used as long as the hole does not penetrate the front and back surfaces. For the purpose of positioning, etc., on the current collector that does not have holes that penetrate the front and back surfaces, most of the current collectors have holes that penetrate the front and back surfaces, even if there are holes that penetrate the front and back surfaces. If not, a current collector having no holes penetrating the front and back surfaces in the present invention can be obtained. The material of the current collector that does not have holes penetrating the front and back surfaces is the voltage / output design of the electricity storage device of the present invention, the type of active material / conductive material / binder included in the electrode layer formed on the current collector, or It is appropriately determined depending on the electrolytic solution, and is not particularly limited. However, when the positive electrode current collector does not have a hole penetrating the front and back surfaces as described in claim 1, that is, as the positive electrode current collector, Aluminum is common, and when the negative electrode current collector does not have a hole penetrating the front and back surfaces as described in claim 2, that is, the negative electrode current collector is generally copper.

An electrode layer containing an active material is formed on a current collector that does not have a hole penetrating the front and back surfaces. The electrode layer is formed on both sides or one side of a current collector that does not have a hole penetrating the front and back surfaces. The electrode layer contains an active material as a main component, and can be formed using a conductive material and a binder as necessary. The type of the binder is not particularly limited, and examples thereof include fluorine resins such as polyvinylidene fluoride and polytetrafluoroethylene, and polyolefins such as fluorine rubber, SBR, acrylic resin, polyethylene, and polypropylene. . The amount of the binder is not particularly limited, and is appropriately determined depending on the average particle diameter, shape, and the like of the active material. For example, the ratio is preferably about 1% to 30% of the weight of the active material. In addition, the type and amount of the conductive material are not particularly limited, and are appropriately determined depending on the electronic conductivity, average particle size, shape, and the like of the active material. Examples of the material include carbon black and acetylene black. Examples thereof include carbon materials such as graphite and metal materials. The amount of the conductive material is not particularly limited, and an amount necessary for obtaining the electrical conductivity of the electrode described later is added. The electrode for the electricity storage device of the present invention is formed on the current collector using a known electrode molding method such as coating molding, press molding, roll molding, etc., using the above active material, if necessary, a conductive material and a binder. And can be manufactured.

The positive electrode active material capable of occluding and releasing lithium in the electricity storage device of the present invention is not particularly limited. For example, activated carbon, an organic semiconductor such as an insoluble infusible substrate containing a polyacene skeleton structure, and lithium Known metal oxides and metal sulfides that can be occluded and released can be used. Examples of the metal oxide include lithium, such as lithium composite cobalt oxide, lithium composite nickel oxide, lithium composite manganese oxide, or a mixture thereof, and a system in which one or more different metal elements are added to these composite oxides. In addition to metal oxides, metal oxides that can occlude and release lithium such as vanadium pentoxide, manganese dioxide, and molybdenum disulfide but do not contain lithium can also be obtained by pre-doping lithium into the positive electrode or negative electrode in power storage devices. It can be used in the present invention.

The negative electrode active material capable of occluding and releasing lithium in the electricity storage device of the present invention is not particularly limited. For example, activated carbon, an organic semiconductor such as an insoluble infusible substrate containing a polyacene skeleton structure, a graphite-based material Materials such as substances, carbon-based substances, tin oxide, silicon oxide, tin, and silicon can be mentioned. In particular, activated carbon and an insoluble and infusible substrate containing a polyacene skeleton structure are examples of preferable materials because of excellent output characteristics.

An electricity storage device according to claim 1 of the present invention is a positive electrode including a positive electrode active material capable of occluding and releasing lithium, a negative electrode including a negative electrode active material capable of occluding and releasing lithium, and an electrolysis obtained by dissolving a lithium salt in a non-aqueous solvent. In the non-aqueous power storage device having a liquid, the positive electrode current collector does not have a hole penetrating the front and back surfaces, and the negative electrode current collector has a hole penetrating the front and back surfaces. FIG. 1 shows an example of a specific basic configuration for explaining an electricity storage device according to claim 1 of the present invention. In FIG. 1, a negative electrode current collector 11 has holes penetrating the front and back surfaces, and an electrode layer 13 containing a negative electrode active material is formed on the current collector. In FIG. 1, the electrode layers 13 are formed on both surfaces of the negative electrode current collector 11 having holes penetrating the front and back surfaces. However, two electrodes having electrode layers formed on one surface of the negative electrode current collector may be used. . On the other hand, the positive electrode current collector 12 does not have a hole penetrating the front and back surfaces, and an electrode layer 15 containing a positive electrode active material is formed on the current collector. In FIG. 1, the electrode layer 15 is formed on one surface of the positive electrode current collector 12. However, an electrode layer containing a positive electrode active material is formed on both surfaces of the current collector, and based on the basic configuration shown in FIG. An electrode unit composed of a separator, a negative electrode, and the like can be stacked or wound to obtain an electricity storage device.

A specific example of lithium pre-doping in the configuration according to claim 1 will be described. According to the configuration of the first aspect, only the negative electrode current collector has a hole penetrating the front and back surfaces, and lithium can pass through the negative electrode current collector. For example, when lithium is pre-doped in the negative electrode active material included in the negative electrode layer 13 (both sides) in FIG. 1, a predetermined amount of lithium metal necessary for pre-doping of both sides is pasted only on one side of the negative electrode layer 13, When the electrolyte is injected, the lithium metal attached to one side of the negative electrode layer 13 is pre-doped with the negative electrode active material contained in the electrode layer on the attached side, and the negative electrode current collector having holes penetrating the front and back surfaces The negative electrode active material contained in the electrode layer that passes through the body 11 and has no lithium metal attached thereto is also pre-doped. Further, in the case of using two negative electrode current collectors having electrode layers formed on one side of a negative electrode current collector having a penetrating hole, lithium metal can be attached to one negative electrode current collector. In this case, it is desirable to select a material that does not cause a reaction such as alloying with lithium for the negative electrode current collector.

In the configuration according to claim 1, when lithium is added to the positive electrode active material included in the positive electrode layer 15 disposed on both sides of the negative electrode on which the electrode layer is formed on the negative electrode current collector 11 in FIG. A predetermined amount of lithium metal necessary for pre-doping into the positive electrode active material is attached to only one of the positive electrode layers 15, the device is assembled, and the electrolyte is injected, the lithium applied to one of the positive electrode layers 15 The metal is pre-doped to the positive electrode active material contained in the electrode layer on the attached side, passes through the negative electrode current collector 11 having a hole penetrating the front and back surfaces, and the lithium metal is contained in the electrode layer not attached. Substances can also be pre-doped. As a matter of course, each positive electrode current collector 12 disposed on both sides of the negative electrode on which the electrode layer is formed on the negative electrode current collector 11 is electrically connected.

In any case, lithium only passes through the negative electrode current collector having a hole penetrating the front and back surfaces of one layer, and penetrates the front and back surfaces of a plurality of layers as described in Patent Documents 3 to 6. Compared with the case of passing through a current collector having holes, it can be pre-doped uniformly in a short time. Moreover, compared with the case where a negative electrode does not have the hole which penetrates front and back, the thickness of a lithium metal can use the thing of double thickness, and it becomes easy by the handling and manufacturing surface of a lithium metal. Furthermore, since a current collector having a special through-hole is used only on the negative electrode side, compared to the case where it is used for both the positive electrode and the negative electrode described in Patent Documents 3 to 6, from the viewpoint of cost and production, It will be advantageous.

The electricity storage device according to claim 2 of the present invention is a positive electrode including a positive electrode active material capable of occluding and releasing lithium, a negative electrode including a negative electrode active material capable of occluding and releasing lithium, and an electrolysis obtained by dissolving a lithium salt in a non-aqueous solvent. In a non-aqueous power storage device having a liquid, the positive electrode current collector has a hole penetrating the front and back surfaces, and the negative electrode current collector does not have a hole penetrating the front and back surfaces. FIG. 2 shows an example of a specific basic configuration for explaining the electricity storage device according to claim 2 of the present invention. In FIG. 2, the positive electrode current collector 22 has holes penetrating the front and back surfaces, and an electrode layer 25 containing a positive electrode active material is formed on the current collector. In FIG. 2, the electrode layers 25 are formed on both surfaces of the positive electrode current collector 22 having holes penetrating the front and back surfaces, but two electrodes having electrode layers formed on one surface of the positive electrode current collector may be used. . On the other hand, the negative electrode current collector 21 does not have a hole penetrating the front and back surfaces, and an electrode layer 23 containing a negative electrode active material is formed on the current collector. In FIG. 2, the electrode layer 23 is formed on one surface of the negative electrode current collector 21, but an electrode layer containing a negative electrode active material is formed on both surfaces of the current collector, and based on the basic configuration shown in FIG. An electrode unit composed of a separator, a negative electrode, and the like can be stacked or wound to obtain an electricity storage device.

A specific example of lithium pre-doping in the configuration according to claim 2 will be described. According to the configuration of the second aspect, only the positive electrode current collector has a hole penetrating the front and back surfaces, and lithium can pass through the positive electrode current collector. For example, when lithium is predoped in the positive electrode active material contained in the positive electrode layer 25 (both sides) in FIG. 2, a predetermined amount of lithium metal necessary for predoping of both sides is pasted only on one side of the positive electrode layer 25, and the device When the electrolyte is injected, the lithium metal attached to one surface of the positive electrode layer 25 is predoped with the positive electrode active material contained in the electrode layer on the attached side, and the positive electrode current collector having holes penetrating the front and back surfaces The positive electrode active material contained in the electrode layer which passes through the body 22 and is not attached is pre-doped. In addition, in the case of using two positive electrode current collectors each having an electrode layer formed on one side of a positive electrode current collector having a through-hole, lithium metal can be attached to one positive electrode current collector. In this case, it is desirable to select a material that does not cause a reaction such as alloying with lithium for the positive electrode current collector.

3. In the configuration according to claim 2, when lithium is pre-doped into the negative electrode active material included in the negative electrode layer 23 disposed on both sides of the positive electrode on which the electrode layer is formed on the positive electrode current collector 22 in FIG. When a predetermined amount of lithium metal necessary for pre-doping into the negative electrode active material is attached to only one of the negative electrode layers 23, a device is assembled, and an electrolytic solution is injected, the lithium applied to one negative electrode layer 23 The metal is pre-doped to the negative electrode active material contained in the electrode layer on the affixed side, passes through the positive electrode current collector 22 having holes penetrating the front and back surfaces, and the lithium metal is contained in the electrode layer not affixed. Substances can also be pre-doped. As a matter of course, the negative electrode current collectors 21 arranged on both sides of the positive electrode on which the electrode layer is formed on the positive electrode current collector 22 are electrically connected.

Even in the configuration according to claim 2, lithium only passes through the positive electrode current collector having holes penetrating the front and back surfaces of one layer, and as described in Patent Documents 3 to 6, Compared with the case of passing through a current collector having holes penetrating the front and back surfaces, it can be pre-doped uniformly in a short time. Moreover, compared with the case where a positive electrode does not have the hole which penetrates front and back, the thickness of a lithium metal can use a 2 times thickness, and it becomes easy by the handling and manufacturing surface of lithium metal. Furthermore, since a current collector having a special through-hole is used only on the negative electrode side, compared to the case where it is used for both the positive electrode and the negative electrode described in Patent Documents 3 to 6, from the viewpoint of cost and production, It will be advantageous.

Whether to select the configuration according to claim 1 or the configuration according to claim 2 is appropriately determined depending on the power storage device design, the expected energy density, the output density, etc., and has a hole penetrating the front and back surfaces. When using a current collector, the higher the electrical conductivity of the electrode, the better the output characteristics. Compared to the positive electrode active material and the negative electrode active material, the front and back surfaces of the active material have high electrical conductivity. It is preferable to select a configuration using a current collector having holes.

The electrolytic solution in which the lithium salt used in the electricity storage device of the present invention is dissolved in a non-aqueous solvent is appropriately determined according to the use conditions such as the type of the positive electrode material, the properties of the negative electrode material, and the charging voltage. Examples of the non-aqueous electrolyte containing a lithium salt include lithium salts such as LiPF ₆ , LiBF ₄ , LiClO ₄ , propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, dimethoxyethane, γ-butyrolactone, acetic acid. What was melt | dissolved in the organic solvent which consists of 1 type, or 2 or more types, such as methyl and methyl formate, can be used. The concentration of the electrolytic solution is not particularly limited, but generally about 0.5 to 2 mol / l is practical. As a matter of course, it is preferable to use an electrolytic solution having a water content of 100 ppm or less. Moreover, it is also possible to use a well-known gel electrolyte and solid electrolyte.

In the electricity storage device of the present invention, when a separator is disposed between the positive electrode and the negative electrode for the purpose of insulation and electrolyte holding, the separator is not particularly limited, and a polyethylene microporous film, a polypropylene microporous film, Alternatively, there are a laminated film of polyethylene and polypropylene, a woven fabric made of cellulose, glass fiber, aramid fiber, polyacrylonitrile fiber, or a non-woven fabric, which can be appropriately determined according to the purpose and situation.

The shape of the electricity storage device of the present invention is not particularly limited, and can be appropriately determined according to the purpose, such as a coin shape, a cylindrical shape, a square shape, and a film shape.

  EXAMPLES Examples will be shown below to further clarify the features of the present invention, but the present invention is not limited to the examples.

  (1) A phenolic resin cured body 301 g was placed in a stainless steel dish, and the dish was placed in a square furnace (400 mm × 400 mm × 400 mm) and subjected to a thermal reaction. The thermal reaction was performed in a nitrogen atmosphere, and the nitrogen flow rate was 5 liters / minute. The thermal reaction was performed at a rate of 1 ° C./minute until the furnace temperature was raised from room temperature to 630 ° C., held at that temperature for 4 hours, then cooled to 60 ° C. by natural cooling, and the dish was removed from the furnace. The insoluble and infusible substrate of the present invention was obtained. The yield was 180g.

  (2) The insoluble and infusible substrate containing the resulting polyacene skeleton structure was pulverized to an average particle size of 5.4 μm using a planetary ball mill. The obtained insoluble and infusible substrate material was subjected to elemental analysis (measuring instrument: elemental analyzer “PE2400 series II” manufactured by PerkinElmer, Inc., CHNS / O). In the elemental analysis, the atomic ratio of hydrogen atoms / carbon atoms was 0.27.

(3) Next, 66.7 parts by weight of the insoluble infusible substrate containing the above polyacene skeleton structure, 19 parts by weight of conductive material acetylene black, and 14.3 parts by weight of PVdF (polyvinylidene fluoride) were added to NMP (N-methyl). -2-pyrrolidone) was mixed with 230 parts by weight to obtain a negative electrode mixture slurry. This slurry was formed on both sides of a copper punching foil (current collector having through holes of the present invention) having a hole diameter of 0.3 mm (circular and corresponding to the width of the holes in the present invention), a porosity of 50%, and a thickness of 14 μm. After coating, drying, press working was performed to obtain an electrode. The thickness of the electrode was 62 μm, and the density of the electrode layer was 0.79 g / cm ³ . The electrode front and back surfaces of the electrode having electrode layers formed on both sides of the obtained copper punching foil are sandwiched between cylindrical terminals with a diameter of 2 mmΦ made of copper, and a pressure of ² kgf / cm ² is applied between the upper and lower terminals. The current flowing when a voltage of 1 V was applied to the electrode was measured (hereinafter, the electric conductivity was measured by this method), and the electric conductivity of the electrode was determined to be 1.0 × 10 ⁻¹ S / cm.

(4) 93 parts by weight of commercially available activated carbon, 7 parts by weight of conductive material ketjen black and 17 parts by weight of PVdF were mixed with 355 parts by weight of NMP to obtain a positive electrode mixture slurry. The positive electrode mixture slurry is applied to one side of an aluminum foil (current collector having no through-holes) with a thickness of 30 μm, which has been preliminarily coated with a graphite-based conductive paint, dried, and then pressed to obtain the thickness of the electrode. An electrode having a thickness of 105 μm and an electrode layer density of 0.60 g / cm ³ was obtained. The electric conductivity of the electrode was 1.2 × 10 ⁻¹ S / cm.

(5) An electrode layer having an insoluble infusible substrate containing the polyacene skeleton structure as an active material and an electrode formed on both sides on a current collector having a through hole is used as a negative electrode, and the two activated carbon electrodes are used as a positive electrode. Thus, an electricity storage device having a basic structure as shown in FIG. 1 was assembled. Here, a lithium metal having a thickness of 30 μm on one side of an electrode layer using an insoluble infusible substrate containing a polyacene skeleton structure as an active material (950 mAh / g with respect to an insoluble infusible substrate containing a polyacene skeleton structure) Equivalent). After injecting a solution in which LiPF ₆ was dissolved at a concentration of 1 mol / l into a solvent in which ethylene carbonate and methyl ethyl carbonate were mixed at a ratio of 3: 7 (volume ratio) as an electrolytic solution, the cell was disassembled two days later, and the attached lithium The metal was completely gone. In Patent Document 6, when using a current collector having through holes in both the positive electrode and the negative electrode, it is necessary to leave the pre-doping for 14 days until confirmation of completion of the pre-doping, whereas in the present invention, the pre-doping is performed in a short time. It became possible to complete.

  (6) A similarly fabricated cell was charged to 4.0 V with a constant current of 500 mA, and then discharged to 2.0 V with a current of 10 mA. The capacity at this time was 9.89 mAh. Subsequently, after discharging in the same manner as described above, when discharging with a current of 1 A corresponding to 100 C, the capacity was 6.07 mAh.

(7) Next, as a comparison, 66.7 parts by weight of the insoluble infusible substrate containing the polyacene skeleton structure, 19 parts by weight of conductive material acetylene black, and 14.3 parts by weight of PVdF (polyvinylidene fluoride) are added to NMP. A negative electrode mixture slurry was obtained by mixing with 230 parts by weight of (N-methyl-2-pyrrolidone). This slurry was applied to both sides of a copper foil having a thickness of 14 μm (current collector having no through hole), dried, and then pressed to obtain an electrode. The thickness of the electrode was 61 μm, and the density of the electrode layer was 0.8 g / cm ³ . The electric conductivity of the obtained electrode was determined to be 1.1 × 10 ⁻¹ S / cm.

(8) Since the electrode obtained above uses a current collector that does not have a through-hole, lithium metal equivalent to 950 mAh / g is used for an insoluble infusible substrate containing a polyacene skeleton structure. When pre-doping is used, it is necessary to apply 15 μm thick metal lithium to the electrode layers on both sides of the current collector. However, it is difficult to produce metal lithium having a thickness of 15 μm. However, it was difficult to handle because of its weakness in strength. Therefore, as a comparison, lithium metal is arranged on both sides of the electrode in which the electrode layer is formed on both sides of the current collector having no through hole, and ethylene carbonate and methyl ethyl carbonate are used as the electrolyte solution in a ratio of 3: 7 (volume ratio). An electrochemical cell was prepared using a solution in which LiPF ₆ was dissolved in the solvent mixed in 1 to a concentration of 1 mol / l. Using this cell, an amount corresponding to 1000 mAh / g per weight of an insoluble infusible substrate containing a polyacene skeleton structure as an active material was pre-doped.

(9) An electrode in which an electrode layer using an insoluble infusible substrate containing a polyacene skeleton structure predoped as described above as an active material is formed on both sides on a current collector having no through-holes is used as a negative electrode. Two activated carbon electrodes having a thickness of 106 μm and an electrode layer density of 0.60 g / cm ³ were placed on both sides of the negative electrode with positive electrodes (electrode layers formed on a current collector having no through holes). An electrochemical cell (comparative cell) was prepared using a solution obtained by dissolving LiPF ₆ at a concentration of 1 mol / l in a solvent in which ethylene carbonate and methyl ethyl carbonate were mixed at a volume ratio of 3: 7 as an electrolytic solution.

(10) Similarly, the prepared comparative cell was charged to 4.0 V with a constant current of 500 mA, and then discharged to 2.0 V with a current of 10 mA. The capacity at this time was 10.0 mAh. Subsequently, when the battery was discharged with a current of 1 A corresponding to 100 C after charging as described above, the capacity was 6.57 mAh.
Even when a current collector having a through hole is used as the negative electrode current collector, the same capacity and output can be obtained as compared with an electrode using a current collector that does not have a through hole. confirmed.

(1) 93 parts by weight of commercially available activated carbon, 7 parts by weight of conductive material ketjen black and 17 parts by weight of PVdF were mixed with 355 parts by weight of NMP to obtain a positive electrode mixture slurry. This slurry was pre-coated with a graphite-based conductive paint and had a hole diameter of 0.3 mm (circular and corresponding to the width of the hole in the present invention), an aluminum punching foil having a porosity of 50% and a thickness of 20 μm (the through hole of the present invention). Was applied to both sides of the current collector), dried, and pressed to obtain an electrode. The thickness of the electrode was 105 μm, and the density of the electrode layer was 0.60 g / cm ³ . The electric conductivity of the electrode was 1.0 × 10 ⁻¹ S / cm.

(2) 66.7 parts by weight of an insoluble infusible substrate containing the polyacene skeleton structure of Example 1, 19 parts by weight of conductive material acetylene black, and 14.3 parts by weight of PVdF (polyvinylidene fluoride) were added to NMP (N-methyl). -2-pyrrolidone) was mixed with 230 parts by weight to obtain a negative electrode mixture slurry. A negative electrode mixture slurry was applied to one side of a 14 μm thick copper foil (current collector having no through-holes), dried, and pressed to obtain an electrode. The thickness of the electrode was 61 μm, and the density of the electrode layer was 0.80 g / cm ³ . The electric conductivity of the electrode was 1.1 × 10 ⁻¹ S / cm.

(3) Two electrodes using the activated carbon electrode layer as a positive electrode formed on both sides of a current collector having a through-hole and the insoluble infusible substrate containing the polyacene skeleton structure as an active material An electricity storage device having a basic structure as shown in FIG. 2 was assembled as a negative electrode. Here, a lithium metal having a thickness of 30 μm on one side of an electrode layer using an insoluble infusible substrate containing a polyacene skeleton structure as an active material (950 mAh / g with respect to an insoluble infusible substrate containing a polyacene skeleton structure) Equivalent). After pouring a solution in which LiPF ₆ was dissolved at a concentration of 1 mol / l into a solvent in which ethylene carbonate and methyl ethyl carbonate were mixed at a volume ratio of 3: 7 as an electrolytic solution, the cell was left at room temperature. When the cell left for 2 days was disassembled, the attached lithium metal was completely lost.

(4) A similarly fabricated cell was charged to 4.0 V with a constant current of 500 mA, and then discharged to 2.0 V with a current of 10 mA. The capacity at this time was 9.95 mAh. Subsequently, after discharging in the same manner as described above, when discharging with a current of 1 A corresponding to 100 C, the capacity was 5.95 mAh.
Even when a current collector having a through hole is used as the positive electrode current collector, the same capacity and output are obtained as compared with an electrode using a current collector that does not have a through hole. confirmed.

In this example, an electricity storage device using an insoluble infusible substrate containing activated carbon as a positive electrode and a polyacene-based skeleton structure as a negative electrode is illustrated, but the active material of the electricity storage device of the present invention is not limited.

  The electrode for an electricity storage device and the electricity storage device of the present invention can be used for, for example, a power source for portable equipment, an electric vehicle, a hybrid electric vehicle, a fuel cell electric vehicle, etc. Therefore, a simple and practical pre-doping method is possible, which contributes to an increase in energy density and an increase in output by increasing the capacity and voltage of an electricity storage device.

It is explanatory drawing which shows the basic composition of the electrical storage device which concerns on one embodiment of Claim 1 of this invention. It is explanatory drawing which shows the basic composition of the electrical storage device which concerns on one embodiment of Claim 2 of this invention.

Explanation of symbols

11 Negative electrode current collector (having through holes)
12 Cathode current collector (no through hole)
13 Negative electrode layer 14 Separator 15 Positive electrode layer 21 Negative electrode current collector (no through hole)
22 Positive electrode current collector (having through holes)
23 Negative electrode layer 24 Separator 25 Positive electrode layer

Claims (3)

In a non-aqueous electricity storage device having a positive electrode containing a positive electrode active material capable of occluding and releasing lithium, a negative electrode containing a negative electrode active material capable of occluding and releasing lithium, and an electrolyte solution obtained by dissolving lithium salt in a non-aqueous solvent. An electricity storage device, wherein the body does not have a hole penetrating the front and back surfaces, and the negative electrode current collector has a hole penetrating the front and back surfaces. In a non-aqueous electricity storage device having a positive electrode containing a positive electrode active material capable of occluding and releasing lithium, a negative electrode containing a negative electrode active material capable of occluding and releasing lithium, and an electrolyte solution obtained by dissolving lithium salt in a non-aqueous solvent. An electricity storage device, wherein the body has holes that penetrate the front and back surfaces, and the negative electrode current collector does not have holes that penetrate the front and back surfaces. The electricity storage device according to claim 1 or 2, wherein the current collector having holes penetrating the front and back surfaces has a porosity of 10% or more and 90% or less.

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