JP2012004491A - Power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device in which internal resistance is reduced, an lithium ion is doped to a negative electrode in short time, and electrodes are uniformly formed.SOLUTION: A power storage device is formed of a unit including a nonaqueous electrolyte 7 containing a lithium ion, a lithium ion supply source 6, an positive electrode capable of reversibly carrying an anion or a cation, and a negative electrode capable of reversibly doping the lithium ion for alternately laminating the positive electrode and the negative electrode through a separator 3. As for the positive electrode or the negative electrode having a collector formed by coating electrode paint containing a positive electrode active material or a negative electrode active material to one side or both sides thereof, the collector having a through hole with an average diameter of not less than 0.3 μm and not more than 1.0 μm and an aperture of not less than 0.1% and not more than 1.0% is used.

Description

  The present invention relates to an electricity storage device called a hybrid capacitor or a secondary battery.

  In recent years, there is an increasing expectation for power storage devices as high power applications for driving hybrid vehicles and the like that require large currents, and as power auxiliary supply sources.

  Recently, as these applications, a power storage device called a hybrid capacitor using a polarizable electrode as used for an electric double layer capacitor in the positive electrode and a carbon material capable of inserting and extracting lithium ions in the negative electrode Has been proposed. This hybrid capacitor has the feature that high withstand voltage and high energy density can be achieved by increasing the voltage of the hybrid capacitor (potential difference between the positive electrode potential and the negative electrode potential) by doping lithium ions into the negative electrode in advance. Yes.

  The lithium ion doping technology can also be applied to lithium ion secondary batteries, and by doping lithium ions into the negative electrode, it becomes possible to use a high-capacity compound that does not contain lithium as the positive electrode active material, Since the positive electrode active material itself does not involve a chemical reaction in which lithium ions are doped and desorbed, an electricity storage device having an excellent charge / discharge cycle can be provided.

  Patent Documents 1 and 2 propose secondary batteries or capacitors in which lithium ions are doped into the negative electrode by bringing lithium metal and the negative electrode into electrochemical contact.

  In particular, in Patent Document 1, each of the positive electrode current collector and the negative electrode current collector has holes penetrating the front and back surfaces, and the porosity thereof is 1% or more and 30% or less, and the negative electrode active material reversibly absorbs lithium. It is possible to support lithium from the negative electrode by contacting the positive electrode or lithium disposed opposite to the negative electrode and the negative electrode electrochemically, so that all or a part of the lithium is made into the negative electrode adjacent to the lithium. There has been proposed an organic electrolyte battery in which at least one positive electrode is permeated and supported on the other negative electrode.

International Publication No. 2000/007255 International Publication No. 2003/003395

  However, the method of doping lithium ions into the negative electrode by bringing lithium metal and the negative electrode into electrochemical contact as in Patent Documents 1 and 2 requires a considerable amount of time for doping, and therefore the process time can be shortened. It is a problem.

  Further, a current collector having many through-holes on the front and back surfaces as in Patent Document 1 has a high contact resistance with an electrode layer produced by applying a slurry-like electrode paint containing an active material. The problem is that the internal resistance of the capacitor increases and a high capacity cannot be obtained at a high current. Furthermore, in a current collector having many through holes on the front and back surfaces, when applying a slurry-like electrode paint containing an active material, it tends to come off to the opposite side of the coated surface, and a uniform electrode cannot be produced. In order to produce a uniform electrode, there is a problem that a special high-cost vertical coater must be used.

  In the present invention, in order to solve the above-mentioned problems, the time required for the work process is shortened by controlling the size, the opening ratio, the thickness, etc. of the through-holes applied to the current collector and the active material contained in the positive electrode and the negative electrode. Thus, an electrical storage device having improved electrical characteristics such as internal resistance is provided.

  That is, the electricity storage device of the present invention includes a non-aqueous electrolyte containing lithium ions, a lithium supply source, a positive electrode capable of reversibly supporting anions or cations, and a negative electrode capable of reversibly doping lithium ions. An electricity storage device comprising a unit in which the positive electrode and the negative electrode are alternately stacked via a separator, and a lithium supply source is stacked on one or both sides of the outermost unit, the positive electrode active material or the negative electrode active material An electrode paint containing a through-hole having a mean diameter of a current collector constituting the positive electrode or the negative electrode of 0.3 μm or more and 1.0 μm or less by coating on one or both sides, and opening the through-hole The rate is from 0.1% to 1.0%.

  The electricity storage device of the present invention is characterized in that the current collector has a thickness of 8 μm or more and 50 μm or less.

  In the electricity storage device of the present invention, the positive electrode active material contained in the positive electrode and the negative electrode active material contained in the negative electrode have a particle size (D50) corresponding to a cumulative volume fraction of 50% of 1.0 μm or more and 8.0 μm or less. It is characterized by.

  The electricity storage device of the present invention is characterized in that an electrode having a thickness of 1 μm or more and 30 μm or less of the negative electrode and the positive electrode excluding the current collector is used.

  According to the present invention, an electrode in which an electrode paint containing an active material is applied to one or both sides of a current collector has through-holes having an average diameter of 0.3 μm or more and 1.0 μm or less, and an open area ratio is By using a current collector of 0.1% or more and 1.0% or less, the contact resistance with the electrode layer produced by applying the slurry-like electrode paint containing the active material is lowered, so that the inside of the electricity storage device The resistance is reduced, and a high capacity is obtained at a high current.

  In addition, the negative electrode and the lithium metal foil are sealed in a container together with a non-aqueous electrolyte solution, and doped in advance with lithium ionized, that is, it has the minimum through-holes necessary for pre-doping. Therefore, uniform and quick dope can be performed. Furthermore, by using the above-described current collector, it is possible to uniformly apply a slurry-like electrode paint containing an active material without using a special coating apparatus.

  By reducing the thickness of the current collector to 8 μm or more and 50 μm or less, the number of stacked layers per unit can be increased to increase the area, and the resistance of the power storage device can be reduced. Moreover, the doping time of the lithium ion to a negative electrode is shortened by making it thin.

  When the positive electrode active material contained in the positive electrode and the negative electrode active material contained in the negative electrode are made to have a D50 of 1.0 μm or more and 8.0 μm or less, conduction between particles is facilitated, and the internal resistance of the electricity storage device is further reduced.

  When the thickness of one side of the negative electrode and the positive electrode excluding the current collector is thinly applied to 30 μm or less, the diffusion resistance of lithium ions in the electrolytic solution is reduced, the internal resistance of the electricity storage device is further reduced, and the capacity at high current is Increase.

  Further, when thin electrodes are used, the number of stacked layers per unit can be increased, so that the opposing area can be increased and the internal resistance can be reduced.

  Furthermore, by reducing the thickness of the electrode, it is possible to provide an electricity storage device in which the doping time of lithium ions into the negative electrode is shortened.

The schematic cross section of the electrical storage device of this invention.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view of an electricity storage device of the present invention.

  An electrode capable of reversibly supporting anions or cations is used on one side 1 of the positive electrode excluding the current collector, and an electrode capable of reversibly doping lithium ions is used on one side 2 of the negative electrode excluding the current collector. . One side 1 of the positive electrode excluding the current collector is arranged on both sides of the positive electrode current collector 4 for taking out electric charges to form a positive electrode. Similarly, one side 2 of the negative electrode excluding the current collector is disposed on both sides of the negative electrode current collector 5 for taking out electric charges to form a negative electrode.

  A unit in which the negative electrode and the positive electrode are alternately stacked via the separator 3 is configured so that the negative electrode is the outermost part. A lithium storage source 6 is laminated on one or both sides on the outermost part of the unit, and an electricity storage device is manufactured as a structure impregnated with an electrolyte solution 7 that is a non-aqueous solution containing lithium ions.

  The present invention has been made to reduce the internal resistance of an electricity storage device and to dope lithium ions into the negative electrode in a short time, and to make a uniform electrode. An aqueous electrolyte solution, a lithium supply source, a positive electrode capable of reversibly supporting anions or cations, and a negative electrode capable of reversibly doping lithium ions are provided, and the positive electrode and the negative electrode are alternately stacked via a separator. It is an electricity storage device that consists of a unit and has a lithium supply source laminated on one or both sides of the outermost part of the unit, and for an electrode in which an electrode paint containing an active material is applied to one or both sides of a current collector By using a current collector having a through hole with a diameter of 0.3 μm or more and 1.0 μm or less and an open area ratio of 0.1% or more and 1.0% or less, Since the contact resistance with the electrode layer produced by applying the rally-like electrode paint is lowered, the internal resistance of the electricity storage device is reduced, and a high capacity can be obtained at a high current.

  Moreover, since it has the minimum through-hole required for lithium ion pre-doping, uniform and rapid doping can be performed. Furthermore, it has been found that by using the above-described current collector, a slurry-like electrode paint containing an active material can be uniformly applied without using a special coating apparatus.

  When the average diameter of the through holes is larger than 1.0 μm and the open area ratio is larger than 1.0%, the contact resistance with the electrode layer produced by applying the slurry-like electrode paint containing the active material is increased. For this reason, the internal resistance of the electricity storage device increases, and a high capacity cannot be obtained at a high current. In addition, when applying a slurry-like electrode paint containing a substance, it is difficult to apply, and productivity is reduced and a uniform electrode cannot be produced.

  Further, the lower limit of the average diameter of the through holes is preferably 0.3 μm or more so that lithium ions are pre-doped into the negative electrode uniformly in a short time.

  The lower limit of the opening ratio of the through holes is preferably 0.1% or more from the viewpoint of preventing the lithium insertion from becoming uneven.

  In addition, the application of the size of the through hole and the open area ratio to the current collector may be performed on either the positive electrode side, the negative electrode side, or either one.

  By setting the thicknesses of the negative electrode current collector and the positive electrode current collector having through-holes to 8 μm or more and 50 μm or less, the number of stacked layers per unit can be increased, the area can be increased, and the resistance of the electricity storage device can be reduced. Moreover, the doping time of the lithium ion to a negative electrode is shortened by making it thin.

  If the thickness is less than 8 μm, workability at the time of electrode production is reduced, and there is a possibility that the electrode cannot be produced. On the other hand, if the thickness is greater than 50 μm, the number of stacked layers per unit decreases and the resistance increases. Furthermore, the doping of lithium ions into the negative electrode is slow, and there is a risk of uneven doping.

  By setting the positive electrode active material contained in the positive electrode and the negative electrode active material contained in the negative electrode to D50 of 1.0 μm or more and 8.0 μm or less, the diffusion resistance of lithium ions in the electrolytic solution is reduced and the internal resistance is reduced.

  Furthermore, if the particle diameter is larger than 8.0 μm, there is a possibility that a thin electrode cannot be produced uniformly. On the other hand, when the particle diameter is smaller than 1.0 μm, there is a possibility that the particles may enter the through hole, and there is a concern about an increase in the dope time.

  Examples of the shape of the negative electrode active material include a spherical shape and a flake shape, but any shape may be used.

  By thinly applying the thickness of one side of the negative electrode and the positive electrode excluding the current collector to 30 μm or less, the diffusion resistance of lithium ions in the electrolytic solution is reduced, and the internal resistance of the electricity storage device is further reduced. Capacity increases.

  Moreover, the thickness of the single side | surface of the negative electrode except a collector and a positive electrode becomes 1.0 micrometer or more from the minimum value of D50 of the positive electrode active material contained in a positive electrode, and the negative electrode active material contained in a negative electrode.

  When the thickness of one side of the negative electrode and the positive electrode excluding the current collector is greater than 30 μm, the diffusion resistance of lithium ions at the negative electrode increases and the internal resistance increases. Also, the doping of lithium ions into the negative electrode is slow, and there is a risk of uneven doping. The negative electrode may be either single-sided coating or double-sided coating with respect to the negative electrode current collector.

  Further, by reducing the thickness of the electrode, the doping time of lithium ions into the negative electrode can be shortened.

  Furthermore, when a thin electrode is used, the number of stacked layers per unit can be increased to increase the facing area, and the internal resistance can be reduced.

  The positive electrode current collector and the negative electrode current collector having through-holes are manufactured by various methods such as punching, electrolytic etching treatment, and laser treatment, but are not particularly limited. Moreover, the form and number of through holes are not particularly limited.

  As materials of the current collector and negative electrode current collector of the lithium supply source, various materials generally used for lithium ion secondary batteries and the like can be used, and stainless steel, copper, nickel, etc. can be used respectively. . The current collector may be a rolled foil or an electrolytic foil having through holes. Further, the current collector of the lithium supply source can be of the same thickness as the negative electrode current collector, and it does not matter whether there are through holes.

  As a material of the positive electrode current collector, various materials generally used for lithium ion secondary batteries and the like can be used, and aluminum, stainless steel, and the like can be used.

  The ratio of the single-sided thickness of the negative electrode excluding the current collector / the single-sided thickness of the positive electrode excluding the current collector is not particularly limited.

  For the negative electrode and the positive electrode on one or both sides of the current collector, for example, an electrode paint containing an active material is produced, and a method of coating the current paint on a current collector or a sheet electrode containing an active material is produced. There is a method such as sticking to the body, but any method may be used as long as the negative electrode includes the negative electrode active material and the positive electrode includes the positive electrode active material.

  The negative electrode active material that is the main component of the negative electrode is formed of a material that can be reversibly doped with lithium ions. For example, a graphite material used for a negative electrode of a lithium ion secondary battery, a non-graphitizable carbon material, a carbon material such as coke, a polyacene-based substance, and the like can be mentioned, but considering low resistance and low cost, A graphite material or a non-graphitizable carbon material is preferable.

  The positive electrode active material that is the main component of the positive electrode is formed of a material that can reversibly carry anions or cations. For example, carbon materials such as polarizable phenol resin activated carbon, coconut shell activated carbon, petroleum coke activated carbon, and polyacene can be used. Moreover, the positive electrode material etc. of a lithium ion secondary battery can also be used.

  If necessary, a conductive additive or a binder is added to the positive electrode and the negative electrode. Examples of the conductive assistant include graphite, carbon black, ketjen black, vapor-grown carbon, and carbon nanotube, and carbon black and graphite are particularly preferable. As the binder, for example, a rubber-based binder such as styrene-butadiene rubber (SBR), a fluorine-containing resin such as polytetrafluoroethylene or polyvinylidene fluoride, or a thermoplastic resin such as polypropylene or polyethylene can be used.

  As the lithium ion supply source, a substance capable of supplying lithium ions, such as lithium metal or lithium-aluminum alloy, can be used. The size of the lithium supply source is preferably the same size as the negative electrode or 1-2 mm smaller than that. The thickness can be changed depending on the doping amount of lithium ions, but preferably 5 μm to 400 μm. If it is thicker than 400 μm, the lithium supply source remains, which may cause a problem in safety. If it is thinner than 5 μm, handling may be difficult.

  The unit is a unit in which positive electrodes and negative electrodes are alternately stacked via separators so that the negative electrode is the outermost part, and two or more negative electrodes and one or more positive electrodes are stacked. Any number of units may be used according to the specified capacity. Further, a plurality of units may be stacked by reducing the number of negative electrodes and positive electrodes in the unit.

  In the present invention, means for doping lithium into the negative electrode in advance is not particularly limited. For example, either a method of physically short-circuiting the negative electrode and lithium metal or a method of electrochemically doping may be used. The lithium supply source is laminated on one side or both sides of the portion facing the negative electrode on the outermost part of the unit. When two or more lithium supply sources are stacked, the doping time of lithium ions is further shortened and the lithium supply source is uniformly doped. Therefore, a plurality of units may be stacked, and a lithium supply source may be stacked on all outermost portions of each unit. Laminate location is preferably 2 or more and 10 or less. If only one layer is stacked, the lithium ion dope time becomes long, and there is a possibility that it is not uniformly doped. If it exceeds 10, the lamination process for laminating the lithium supply source becomes complicated, which is not preferable.

  Next, the solvent of the electrolytic solution composed of a non-aqueous solution containing lithium ions is, for example, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, γ-butyl lactone, acetonitrile, dimethoxyethane, tetrahydrofuran. , Dioxolane, methylene chloride, sulfolane and the like. Furthermore, a mixed solvent obtained by mixing two or more of these solvents can also be used. Among these, it is preferable to have at least either propylene carbonate or ethylene carbonate. Moreover, you may add about 0.01-0.5 mol / L additives, such as vinylene carbonate and fluoroethylene carbonate.

The electrolyte to be dissolved in the solvent, as long as it generates lithium upon ionization, for _{example, LiI, LiClO 4, LiAsF 6} , LiBF 4, LiPF 6 , and the like. These solutes are preferably 0.5 mol / L or more in the solvent, and more preferably in the range of 0.5 to 1.5 mol / L.

  In addition, the structure of the electrical storage device of this invention is applicable not only to a hybrid capacitor but to a secondary battery (especially lithium ion secondary battery) etc.

  Examples of the present invention are described in detail below.

Example 1
88 parts by mass of a non-graphitizable carbon material having a D50 of 2 μm, 6 parts by mass of graphite, 5 parts by mass of SBR, 4 parts by mass of carboxymethylcellulose, and 200 parts by mass of water were mixed to obtain a negative electrode slurry.

  Next, the obtained negative electrode slurry was coated on both sides so as to be 20 μm on one side on a 20 μm thick chemically etched copper foil having through holes with an average diameter of 0.9 μm and an open area ratio of 1.0%. Then, after drying, pressing was performed to obtain a negative electrode having a thickness of 60 μm.

  A mixture of 92 parts by mass of activated carbon having a D50 of 2 μm, 8 parts by mass of graphite, 3 parts by mass of SBR, 3 parts by mass of carboxymethyl cellulose, and 200 parts by mass of water has an average diameter of 0.9 μm and a porosity of 1.0%. A 20 μm-thick through aluminum foil having through-holes was coated on both sides to have a thickness of 30 μm, dried and pressed to obtain a positive electrode having a thickness of 80 μm.

Two positive electrodes and three negative electrodes were cut out from the electrode obtained above so that the electrode area of the portion where the active material was applied was 6 cm ² .

  Next, a unit was fabricated by laminating a negative electrode / positive electrode / negative electrode in this order via a 30 μm-thick cell roll separator between the negative electrode and the positive electrode.

  The prepared unit was vacuum-treated at 130 ° C. for 6 hours in a vacuum dryer, and then placed on each outermost side of the unit with one lithium metal facing the negative electrode, and then placed in a container formed of an aluminum laminate film. I put it in.

A non-aqueous electrolyte solution in which 1 mol / L LiPF ₆ was dissolved in a mixed solvent in which ethylene carbonate and propylene carbonate were mixed at a ratio of 1: 1 was poured into an aluminum laminate film and sealed to produce an electricity storage device. .

  The produced electricity storage device was subjected to constant voltage discharge so that 400 mAh / g of lithium ions was doped from the lithium metal to the negative electrode. The dope time at this time was measured.

  In the above state, the battery was charged at 3.8 V with a constant current and constant voltage for 1 hour, and discharged at 80 mA until the cell voltage reached 2.2 V. The internal resistance was calculated from the voltage drop during discharge.

(Example 2)
88 parts by mass of a non-graphitizable carbon material having a D50 of 1 μm, 6 parts by mass of graphite, 5 parts by mass of SBR, 4 parts by mass of carboxymethylcellulose, and 200 parts by mass of water were mixed to obtain a negative electrode slurry.

  Next, the obtained negative electrode slurry was coated on both sides so as to be 20 μm on one side on a 50 μm-thick mesh copper foil having through holes with an average diameter of 0.5 μm and an open area ratio of 1.0%. After drying, pressing was performed to obtain a negative electrode having a thickness of 90 μm.

  A mixture of 92 parts by mass of activated carbon having a D50 of 1 μm, 8 parts by mass of graphite, 3 parts by mass of SBR, 3 parts by mass of carboxymethyl cellulose, and 200 parts by mass of water has an average diameter of 0.5 μm and a porosity of 1.0%. On both sides of a 50 μm-thick penetrating aluminum foil having through-holes of 30 μm on one side, dried and pressed to obtain a 110 μm-thick positive electrode.

Two positive electrodes and three negative electrodes were cut out from the electrode obtained above so that the electrode area of the portion where the active material was applied was 6 cm ² .

  Next, a unit was fabricated by laminating a negative electrode / positive electrode / negative electrode in this order via a 30 μm-thick cell roll separator between the negative electrode and the positive electrode.

  The prepared unit was vacuum-treated at 130 ° C. for 6 hours in a vacuum dryer, and then placed on each outermost side of the unit with one lithium metal facing the negative electrode, and then placed in a container formed of an aluminum laminate film. I put it in.

A non-aqueous electrolyte solution in which 1 mol / L LiPF ₆ was dissolved in a mixed solvent in which ethylene carbonate and propylene carbonate were mixed at a ratio of 1: 1 was poured into an aluminum laminate film and sealed to produce an electricity storage device. .

  The produced electricity storage device was subjected to constant voltage discharge so that 400 mAh / g of lithium ions was doped from the lithium metal to the negative electrode. The dope time at this time was measured.

  In the above state, the battery was charged at 3.8 V with a constant current and constant voltage for 1 hour, and discharged at 80 mA until the cell voltage reached 2.2 V. The internal resistance was calculated from the voltage drop during discharge.

(Example 3)
88 parts by mass of artificial graphite carbon material having a D50 of 8 μm, 6 parts by mass of graphite, 5 parts by mass of SBR, 4 parts by mass of carboxymethyl cellulose, and 200 parts by mass of water were mixed to obtain a negative electrode slurry.

  Next, the obtained negative electrode slurry was coated on both sides so as to be 10 μm on one side on a 10 μm-thick punched copper foil having through holes with an average diameter of 1.0 μm and an open area ratio of 1.0%. After drying, pressing was performed to obtain a negative electrode having a thickness of 30 μm.

  A mixture of 92 parts by mass of activated carbon having a D50 of 8 μm, 8 parts by mass of graphite, 3 parts by mass of SBR, 3 parts by mass of carboxymethyl cellulose, and 200 parts by mass of water has an average diameter of 1.0 μm and a porosity of 1.0%. On both sides of a 10 μm-thick penetrating aluminum foil having through-holes of 20 μm on one side, dried and pressed to obtain a positive electrode having a thickness of 50 μm.

Two positive electrodes and three negative electrodes were cut out from the electrode obtained above so that the electrode area of the portion where the active material was applied was 6 cm ² .

  Next, a unit was fabricated by laminating a negative electrode / positive electrode / negative electrode in this order via a 30 μm-thick cell roll separator between the negative electrode and the positive electrode.

  The prepared unit was vacuum-treated at 130 ° C. for 6 hours in a vacuum dryer, and then placed on each outermost side of the unit with one lithium metal facing the negative electrode, and then placed in a container formed of an aluminum laminate film. I put it in.

A non-aqueous electrolyte solution in which 1 mol / L LiPF ₆ was dissolved in a mixed solvent in which ethylene carbonate and propylene carbonate were mixed at a ratio of 1: 1 was poured into an aluminum laminate film and sealed to produce an electricity storage device. .

  The produced electricity storage device was subjected to constant voltage discharge so that 400 mAh / g of lithium ions was doped from the lithium metal to the negative electrode. The dope time at this time was measured.

  In the above state, the battery was charged at 3.8 V with a constant current and constant voltage for 1 hour, and discharged at 80 mA until the cell voltage reached 2.2 V. The internal resistance was calculated from the voltage drop during discharge.

(Comparative Example 1)
A negative electrode slurry was obtained by mixing 88 parts by mass of a graphitized carbon material having a D50 of 2 μm, 6 parts by mass of graphite, 5 parts by mass of SBR, 4 parts by mass of carboxymethylcellulose, and 200 parts by mass of water.

  Next, the obtained negative electrode slurry was coated on both sides so as to be 20 μm on one side on a 20 μm thick mesh copper foil having through holes with an average diameter of 3 μm and an open area ratio of 1.0%, and dried. After pressing, a negative electrode having a thickness of 60 μm was obtained.

  A mixture of 92 parts by mass of activated carbon having a D50 of 2 μm, 8 parts by mass of graphite, 3 parts by mass of SBR, 3 parts by mass of carboxymethyl cellulose, and 200 parts by mass of water penetrates with an average diameter of 3 μm and a porosity of 1.0%. It coated on both surfaces so that it might become 30 micrometers on one side on a 20-micrometer-thick through aluminum foil which has a hole, it dried and pressed, and the positive electrode of thickness 80 micrometers was obtained.

Two positive electrodes and three negative electrodes were cut out from the electrode obtained above so that the electrode area of the portion where the active material was applied was 6 cm ² .

  Next, a unit was fabricated by laminating a negative electrode / positive electrode / negative electrode in this order via a 30 μm-thick cell roll separator between the negative electrode and the positive electrode.

  The prepared unit was vacuum-treated at 130 ° C. for 6 hours in a vacuum dryer, and then placed on each outermost side of the unit with one lithium metal facing the negative electrode, and then placed in a container formed of an aluminum laminate film. I put it in.

A non-aqueous electrolyte solution in which 1 mol / L LiPF ₆ was dissolved in a mixed solvent in which ethylene carbonate and propylene carbonate were mixed at a ratio of 1: 1 was poured into an aluminum laminate film and sealed to produce an electricity storage device. .

  The produced electricity storage device was subjected to constant voltage discharge so that 400 mAh / g of lithium ions was doped from the lithium metal to the negative electrode. The dope time at this time was measured.

  In the above state, the battery was charged at 3.8 V with a constant current and constant voltage for 1 hour, and discharged at 80 mA until the cell voltage reached 2.2 V. The internal resistance was calculated from the voltage drop during discharge.

(Comparative Example 2)
88 parts by mass of a non-graphitizable carbon material having a D50 of 3 μm, 6 parts by mass of graphite, 5 parts by mass of SBR, 4 parts by mass of carboxymethylcellulose, and 200 parts by mass of water were mixed to obtain a negative electrode slurry.

  Next, the obtained negative electrode slurry was coated on both sides of a punched copper foil having an average diameter of 0.2 μm and a hole area ratio of 1.0% so as to have a thickness of 20 μm on one side. After drying, pressing was performed to obtain a negative electrode having a thickness of 120 μm.

  A mixture of 92 parts by mass of activated carbon having a D50 of 3 μm, 8 parts by mass of graphite, 3 parts by mass of SBR, 3 parts by mass of carboxymethyl cellulose, and 200 parts by mass of water has an average diameter of 0.2 μm and a porosity of 1%. On both sides of the aluminum foil having a thickness of 80 μm, coating was performed on both sides so as to be 30 μm on one side, followed by drying and pressing to obtain a positive electrode having a thickness of 140 μm.

Two positive electrodes and three negative electrodes were cut out from the electrode obtained above so that the electrode area of the portion where the active material was applied was 6 cm ² .

  Next, a unit was fabricated by laminating a negative electrode / positive electrode / negative electrode in this order via a 30 μm-thick cell roll separator between the negative electrode and the positive electrode.

  The prepared unit was vacuum-treated at 130 ° C. for 6 hours in a vacuum dryer, and then placed on each outermost side of the unit with one lithium metal facing the negative electrode, and then placed in a container formed of an aluminum laminate film. I put it in.

A non-aqueous electrolyte solution in which 1 mol / L LiPF ₆ was dissolved in a mixed solvent in which ethylene carbonate and propylene carbonate were mixed at a ratio of 1: 1 was poured into an aluminum laminate film and sealed to produce an electricity storage device. .

  The produced electricity storage device was subjected to constant voltage discharge so that 400 mAh / g of lithium ions was doped from the lithium metal to the negative electrode. The dope time at this time was measured.

  In the above state, the battery was charged at 3.8 V with a constant current and constant voltage for 1 hour, and discharged at 80 mA until the cell voltage reached 2.2 V. The internal resistance was calculated from the voltage drop during discharge.

(Comparative Example 3)
88 parts by mass of a non-graphitizable carbon material having a D50 of 2 μm, 6 parts by mass of graphite, 5 parts by mass of SBR, 4 parts by mass of carboxymethylcellulose, and 200 parts by mass of water were mixed to obtain a negative electrode slurry.

  Next, the obtained negative electrode slurry was coated on both sides so as to be 50 μm on one side on a 20 μm thick mesh copper foil having through holes with an average diameter of 0.2 μm and a porosity of 1%, and dried. After pressing, a negative electrode having a thickness of 120 μm was obtained.

  A mixture of 92 parts by mass of activated carbon having a D50 of 3 μm, 8 parts by mass of graphite, 3 parts by mass of SBR, 3 parts by mass of carboxymethyl cellulose, and 200 parts by mass of water penetrates with an average diameter of 0.2 μm and a porosity of 1%. It coated on both surfaces so that it might become 60 micrometers on one side on the 20-micrometer-thick through aluminum foil which has a hole, it dried and pressed, and the positive electrode of thickness 140 micrometers was obtained.

Two positive electrodes and three negative electrodes were cut out from the electrode obtained above so that the electrode area of the portion where the active material was applied was 6 cm ² .

  Next, a unit was fabricated by laminating a negative electrode / positive electrode / negative electrode in this order via a 30 μm-thick cell roll separator between the negative electrode and the positive electrode.

  The prepared unit was vacuum-treated at 130 ° C. for 6 hours in a vacuum dryer, and then placed on each outermost side of the unit with one lithium metal facing the negative electrode, and then placed in a container formed of an aluminum laminate film. I put it in.

A non-aqueous electrolyte solution in which 1 mol / L LiPF ₆ was dissolved in a mixed solvent in which ethylene carbonate and propylene carbonate were mixed at a ratio of 1: 1 was poured into an aluminum laminate film and sealed to produce an electricity storage device. .

  The produced electricity storage device was subjected to constant voltage discharge so that 400 mAh / g of lithium ions was doped from the lithium metal to the negative electrode. The dope time at this time was measured.

  In the above state, the battery was charged at 3.8 V with a constant current and constant voltage for 1 hour, and discharged at 80 mA until the cell voltage reached 2.2 V. The internal resistance was calculated from the voltage drop during discharge.

  Table 1 shows the measurement results of the doping time and internal resistance in Examples 1 to 3 and Comparative Examples 1 to 3. The average diameter, the porosity, and the thickness of the current collector indicate values of either the positive electrode current collector or the negative electrode current collector. The active material D50 indicates a particle size value corresponding to a cumulative volume fraction of 50% of the positive and negative electrode active materials, and the positive and negative electrode thicknesses indicate the thickness of one side excluding the current collector.

  When Examples 1, 2, and 3 are compared with Comparative Example 1, when the average diameter of the through-holes of the current collector is large, the active material particles enter the through-holes, thereby increasing the internal resistance and the required time for doping. Has been confirmed. When Examples 1, 2, and 3 were compared with Comparative Example 2, when the current collector was thick, it took about 2.7 times as long to dope as compared to the thin current collector. Further, when the electrode was made thicker as in Comparative Example 3, it was confirmed that the internal resistance increased about twice as compared with Examples 1, 2, and 3, and further it took time to dope lithium ions. Further, when the open area ratio was larger than 1.0%, the uniform electrode could not be applied as described above, and the above test could not be performed.

  It has been found that it is possible to provide an electricity storage device in which the internal resistance is reduced and the negative electrode is doped with lithium ions in a short time to achieve a more uniform electrode.

  The embodiments of the present invention have been described above using the embodiments. However, the present invention is not limited to these embodiments, and the present invention is not limited to the scope of the present invention. Included in the invention. That is, various changes and modifications that can be naturally made by those skilled in the art are also included in the present invention.

DESCRIPTION OF SYMBOLS 1 One side of positive electrode except current collector 2 One side of negative electrode excluding current collector 3 Separator 4 Positive electrode current collector 5 Negative electrode current collector 6 Lithium supply source 7 Electrolyte

Claims (4)

  A non-aqueous electrolyte containing lithium ions; a lithium supply source; a positive electrode capable of reversibly supporting anions or cations; and a negative electrode capable of reversibly doping lithium ions; An electricity storage device composed of units in which negative electrodes are alternately laminated, with a lithium supply source laminated on one or both sides of the outermost unit, and an electrode paint containing a positive electrode active material or a negative electrode active material on one side or both sides The current collector constituting the positive electrode or the negative electrode has a through hole with an average diameter of 0.3 μm or more and 1.0 μm or less, and the opening ratio of the through hole is 0.1% or more. An electricity storage device characterized by being 0% or less.   The power storage device according to claim 1, wherein the current collector has a thickness of 8 μm or more and 50 μm or less.   The positive electrode active material contained in the positive electrode or the negative electrode active material contained in the negative electrode has a particle diameter (D50) corresponding to a cumulative volume fraction of 50% of 1.0 μm or more and 8.0 μm or less. Item 3. The electricity storage device according to Item 1 or 2.   The electrical storage device according to any one of claims 1 to 3, wherein an electrode having a thickness of 1 μm or more and 30 μm or less of a negative electrode and a positive electrode excluding the current collector is used.

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