JP2015088437A - Pre-doping method of nonaqueous secondary battery and battery obtained by pre-doping method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pre-doping method of the alkali metal ions of a nonaqueous secondary battery which allows for easy handling of an electrode, without pasting a lithium metal or manufacturing a half-cell, and to provide a nonaqueous secondary battery using this method.SOLUTION: In a pre-doping method of a nonaqueous secondary battery having a positive electrode 1 and a negative electrode 2, an electrode 4 for compensation having an alkali metal ion source arranged not in contact with the positive electrode and negative electrode is arranged so as to be immersed in a pre-dope solution 5 where the alkali metal ions are eluted. A DC power supply 8 is connected between any one of the positive or negative battery electrode and the electrode for compensation, so that the direction of an electric field by the DC power supply is identical to the direction of the electrode plane of the battery electrode.

Description

  The present invention relates to a pre-doping method of a non-aqueous secondary battery, a battery obtained by the pre-doping method, and an electric device using the same, and more specifically, suppresses gas generation during battery charging / discharging, and has sufficient alkali metal ions. The present invention relates to a method for pre-doping a battery by supplementing a positive electrode or a negative electrode with alkali metal ions, a non-aqueous secondary battery obtained by this pre-doping method, and an electric device using the same.

  Conventionally, as secondary batteries, batteries of various shapes such as cylindrical batteries and prismatic batteries have been developed and widely used. In addition, a cylindrical type is adopted for a relatively small capacity battery from the viewpoint of pressure resistance and ease of sealing, and a square type is adopted for a relatively large capacity battery for ease of handling.

  If attention is paid to the electrode structure of the secondary battery, two types, a stacked type and a wound type, are widely used. That is, in a stacked type battery, an electrode group in which positive electrodes and negative electrodes are alternately stacked via separators is housed in a battery case. Many of the stacked type batteries have a rectangular battery case. On the other hand, the wound type is housed in a battery case in a state where the positive electrode and the negative electrode are wound in a spiral shape with a separator interposed therebetween. The wound type battery case may be a cylindrical type or a square type.

  Non-aqueous secondary batteries, such as lithium secondary batteries, are used as main power sources for mobile devices such as mobile communication devices, portable game machines, and portable electronic devices because high energy density is obtained at high voltage. . Further, due to environmental problems in recent years, the use as an in-vehicle battery or a backup power supply battery has been expanded.

For example, current lithium secondary batteries generally use lithium-containing transition metal composite oxides such as lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), and lithium iron phosphate (LiFePO ₄ ) for the positive electrode. For the negative electrode, graphite, hard carbon or the like capable of inserting and extracting lithium is used. In addition, electrolytes used for lithium ion batteries are mainly cyclic carbonates such as propylene carbonate (PC) and ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and methyl ethyl carbonate (MEC). Lithium tetrafluoroborate (LiBF ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium hexafluoroarsenate (LiAsF ₆ ), lithium perchlorate (LiClO ₄₎ ), Lithium bistrifluoromethanesulfonylamide (LiN (CF ₃ SO ₂ ) ₂ ), lithium trifluoromethanesulfonate (LiCF ₃ SO ₃ ), and other electrolyte salts are used.
However, since the theoretical capacity of the negative electrode using graphite is only 372 mAh / g, a higher capacity is desired.

  Therefore, elements such as silicon (Si) and tin (Sn), and nitrides, oxides, sulfides, and the like of these elements are known to have a higher capacity than graphite, and thus include these substances. Various alloy negative electrodes have been proposed. However, although alloy-based negative electrodes such as Si and Sn have a high capacity, sufficient cycle life characteristics cannot be obtained because of volume expansion / contraction associated with charge / discharge.

  On the other hand, it is reported that cycle life characteristics can be improved by using a thin Si film (Non-patent Document 1), a high-strength binder (Non-Patent Document 2), and a high-strength current collector (Non-Patent Document 3). .

JP 2009-16285 A JP 2003-7355 A JP 2001-143769 A

J. Electrochem. Soc., 153 (2006) A472. 52nd Battery Symposium Abstracts, 2C23 (2011) Abstracts of the 51st Battery Conference, 1D05 (2010) “Measurement and Analysis Data Collection of Lithium Secondary Battery Materials”, Technical Information Association, p.200-205, (2012).

However, these prior arts can obtain electrodes with a high capacity and a long life, but when used in batteries as they are, an irreversible capacity exists in an alloy-based negative electrode such as Si or Sn, so that the reversibility of the positive electrode There was a problem that the battery capacity was drastically reduced by offsetting the capacity.
Further, even if attention is paid to the positive electrode material, V ₂ O ₅ , sulfur-based materials, and the like do not have Li, and thus do not function as a battery even if they are used as they are.

  Therefore, before assembling the battery, it is necessary to pre-dope alkali metal ions to an electrode having an irreversible capacity such as an alloy-based negative electrode or a positive electrode material not having Li.

  For pre-doping, electrodes were pre-doped using techniques such as (1) pre-doping with an alkali metal thin film, (2) electrochemical pre-doping, and (3) mechanical pre-doping (Non-Patent Document 4).

In the method (1), an alkali metal thin film corresponding to the capacity to be compensated is attached to the electrode, and held in the electrolyte solution, so that alkali metal ions diffuse into the electrode, and the electrode to be compensated becomes Pre-doped.
In the method (2), an alkali metal is used as a counter electrode, a half cell is assembled, and a short circuit or a voltage is applied to electrochemically pre-dope an electrode to be compensated.

In the method (3), the active material of the electrode to be compensated is pre-doped by applying mechanical energy to the alkali metal chip corresponding to the capacity to be compensated and the active material used for the electrode to be compensated using mechanical milling or the like. Let

  However, with the method (1), a single battery with a small capacity is possible, but in the case of a laminated type or wound type battery, a large amount of heat can be generated when an alkali metal thin film is attached to an electrode. There is sex. Moreover, the alkali metal thin film to be used is difficult to handle and the uniformity of the compensated electrode is lacking. In the method (2), it is the easiest at the laboratory level and high-precision pre-doping treatment can be performed. However, after pre-doping, it is necessary to disassemble the battery, take out the alkali metal, and reassemble the battery again. There is a lack of mass productivity even if the battery is large or small. Since the method (3) is pre-doped with an active material in advance, it does not include a pre-doping step after electrode preparation as in the methods (1) and (2), but the active material obtained by the method (3) is not included. The substance is water-resistant and difficult to handle. Unlike the methods (1) and (2), the pre-doping step after electrode preparation is not included. However, the active material obtained by the method (3) is water-free and difficult to handle. .

  The present invention has been made in view of the current state of the prior art described above, and its main purpose is a non-aqueous system that can easily handle electrodes without attaching lithium metal or preparing a half-cell. It is an object to provide a pre-doping method for a secondary battery, a non-aqueous secondary battery using this method, and an electric device using the same.

  A pre-doping method for a non-aqueous secondary battery according to the present invention is a pre-doping method for a non-aqueous secondary battery having a positive electrode and a negative electrode, and the alkali metal ion source is disposed so as not to contact the positive electrode and the negative electrode. The electrode for compensation having the above is disposed so as to be immersed in a pre-doping solution from which alkali metal ions are eluted, and a DC power source is connected between the battery electrode of either the positive electrode or the negative electrode and the electrode for compensation. The direction of the electric field generated by the DC power supply is the same as the direction of the electrode surface of the battery electrode.

  Since the direction of the electric field in the pre-doping solution by the DC power supply is the same as the direction of the electrode surface of the battery electrode, lithium ions can be efficiently pre-doped on the electrode surface of the positive electrode or the negative electrode. The direction of the electrode surface is the same as the direction of extension of the electrode surface of the electrode formed in a flat plate shape and the direction of the electric field generated by the DC power source. An electric field acts along the electrode surface.

  A supplementary electrode having an alkali metal ion source disposed so as not to contact the positive electrode and the negative electrode, the supplemental electrode being alkali metal ions along the electrode surface of the positive electrode surface and the negative electrode surface The positive electrode, the negative electrode, and the filling electrode are immersed in a pre-doping solution in which alkali metal ions can move, and a voltage is applied to the positive electrode or the negative electrode and the filling electrode. A non-aqueous secondary battery pre-doping method in which alkali metal ions are electrochemically supplemented to the positive electrode or the negative electrode by applying.

In the pre-doping method of the non-aqueous secondary battery according to the present invention, the electrode capacity of the filling electrode is larger than the electrode capacity of the electrode, and the surface area of the filling electrode is larger than the cross-sectional area of the electrode.
In the pre-doping method of the non-aqueous secondary battery according to the present invention, the pre-doping solution is 45 to 300 ° C.
The pre-doping method for a non-aqueous secondary battery according to the present invention includes a step of charging and discharging between the positive electrode and the negative electrode after pre-doping.
In the pre-doping method for a non-aqueous secondary battery according to the present invention, the pre-doping solution is an ionic liquid containing an alkali metal salt.

In the pre-doping method for a non-aqueous secondary battery according to the present invention, the negative electrode is a negative electrode using a metal, alloy or compound containing an element of Si or Sn.
In the pre-doping method for a non-aqueous secondary battery according to the present invention, the current collecting base material is made of a material using steel or stainless steel.
The pre-doping method of the non-aqueous secondary battery according to the present invention is such that the positive electrode or the positive electrode is an electrode using a thermosetting resin having heat resistance as a binder, and the active material contained in the positive electrode or the positive electrode When the total of the binder and the conductive additive is 100% by mass, the binder is contained in an amount of 1 to 20% by mass.

The non-aqueous secondary battery according to the present invention is a battery obtained by the above-described pre-doping method for a non-aqueous secondary battery.
A method of supplementing alkali metal ions in a non-aqueous secondary battery of stacked type or wound type in which a positive electrode and a negative electrode are interposed via a separator, and arranged so as not to be in contact with the positive electrode and the negative electrode A pre-doping solution comprising a source electrode and a source electrode arranged in a direction perpendicular to the positive electrode surface and the negative electrode surface, wherein the positive electrode, the negative electrode, and the electrode for replacement can move alkali metal ions This is a pre-doping method for a nonaqueous secondary battery in which alkali metal ions are electrochemically supplemented to the positive electrode or the negative electrode by immersing in and applying a voltage to the supplementary electrode on the positive electrode or the negative electrode. However, the electrode for compensation is larger than the electrode capacity to be compensated, and the surface area of the electrode for compensation is larger than the cross-sectional area of the laminate or the wound body.

  The pre-doping method of the non-aqueous secondary battery according to the present invention is easy and uniform, unlike the conventional pre-doping method in which half-cells are prepared in advance and large heat generation generated during pre-doping and handling of the electrodes is difficult. An excellent pre-doping treatment can be performed. Specifically, the pre-doping treatment of the battery can be performed in a state where the laminated type or wound type battery is assembled. Therefore, the pre-doping method of the non-aqueous secondary battery according to the present invention greatly improves the productivity as compared with the conventional pre-doping method, and it is possible to achieve both high capacity and safety of the battery. It becomes possible to enlarge.

  Since the non-aqueous secondary battery subjected to the pre-doping treatment of the present invention has a high capacity and a long life, it can be used as a power source for various electric devices (including vehicles using electricity).

It is drawing which shows an example of a wound battery. It is drawing which shows an example of a laminated battery. FIG. 3 is a layout diagram of pre-doped electrodes performed in Example 1. FIG. 5 is a layout diagram of pre-doped electrodes performed in Comparative Example 2. FIG. 10 is a layout diagram of pre-doped electrodes performed in Example 11. FIG. 6 is a layout diagram of pre-doped electrodes performed in Comparative Example 4;

  Embodiments according to the present invention will be described below, but the present invention is not limited to these embodiments.

<Manufacture of battery elements>
Prior to description of the invention of the method according to the present invention, individual elements of the battery to which the present invention is applied will be described, and then embodiments will be described. Finally, the test results will be described.

(Positive electrode)
In the present invention, the positive electrode is not particularly limited as long as it is a positive electrode used in a non-aqueous secondary battery.

The positive electrode active material is not particularly limited as long as it is a positive electrode active material used in a non-aqueous secondary battery. Known electrodes including alkali metal transition metal oxides, vanadiums, sulfurs, carbons, organics, etc. are used. The alkali metal transition metal _{oxide-based, ACoO 2, ANiO 2, ANi0.33Mn0.33Co0.33O} 2, AMnO 2, AMn 2 O 4, AFePO 4, AFe 0.5 Mn 0.5 PO 4, AMnPO 4, ANb 2 O 5 , ANbO ₂ , AFeO ₂ , AMgO ₂ , ACAO ₂ , ATiO ₂ , ATiS ₂ , ACrO ₂ , ARuO ₂ , ACuO ₂ , AZnO ₂ , AMoO ₂ , AMoS ₂ , ATAO ₂ , AWO ₂ , and the like. Here, A is a group 1 element of the periodic table and represents an alkali metal element, specifically, Li, NA, or K.
Examples of vanadium include AV ₂ O ₅ and AVO ₂ .
Examples of the sulfur type include sulfur, carbon sulfide, polysulfide carbon, sulfurized polyacrylonitrile, and sulfurized rubber.

  Examples of the carbon system include graphite, soft carbon, hard carbon, and glassy carbon. Organic type includes rubeanic acid, benzoquinones, etc.

Among the positive electrode active materials described above, from the viewpoint of energy density, LiCoO ₂ , LiMn ₂ O ₄ , LiFePO ₄ , LiFe0.5Mn0.5PO ₄ , LiMnPO ₄ , LiNi0.33Mn0.33Co0.33O ₂ , solid solution, vanadium-based, sulfur A system is preferred.

  The conductive auxiliary agent is not particularly limited as long as it has electronic conductivity, and examples thereof include metals, carbon materials, conductive polymers, conductive glasses, and the like, from the viewpoint of high electronic conductivity and oxidation resistance. Carbon materials are preferred. Specific examples include acetylene black (AB), ketjen black (KB), vapor grown carbon fiber powder (VGCF), carbon nanotube (CNT), graphite, graphene, glassy carbon, etc., one or two of these. The above may be used.

  When the total of the active material, binder, and conductive additive contained in the positive electrode is 100% by mass, it is preferable that 0 to 20% by mass of the conductive aid is contained. That is, the conductive auxiliary agent is contained as necessary. When it exceeds 20 mass%, since the ratio of the active material as a battery is small, an electrode capacity density tends to become low.

  The binder is usually used, for example, polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), polyimide (PI), polyamide, polyamideimide, aramid, polyacryl, styrene butadiene rubber (SBR), ethylene. -Vinyl acetate copolymer (EVA), styrene-ethylene-butylene-styrene copolymer (SEBS), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), polyvinyl butyral (PVB), ethylene vinyl alcohol, polyethylene (PE) , Polypropylene (PP), polyacrylic acid, alginic acid and the like may be used alone or in combination of two or more.

Among these, the binder is preferably a thermosetting resin having heat resistance. Examples thereof include materials such as polyimide (PI), polyamide, polyamideimide, aramid, polyacrylic acid and the like. These thermosetting resins can suppress the swelling of the binder in the electrolytic solution and improve the cycle life characteristics of the battery.
When the total of the active material, binder, and conductive additive contained in the positive electrode is 100% by mass, the binder is preferably contained in an amount of 1-20% by mass.

  When the binder content is less than 1% by mass, the electrode has low mechanical strength, so that the active material easily falls off and the cycle life characteristics of the battery deteriorate. On the other hand, when it exceeds 20% by mass, the alkali metal ion conductivity is low, the electrical resistance is high, the pre-doping process takes time, and the ratio of the active material as the battery is small, so the electrode capacity density is low. Prone.

  The current collector used for the positive electrode is not particularly limited as long as it is a material that has electronic conductivity and can conduct electricity to the held positive electrode active material. For example, conductive materials such as C, Ti, Cr, Ni, Cu, Mo, Ru, Rh, TA, W, Os, Ir, Pt, Au, Al, and alloys containing two or more of these conductive materials ( For example, stainless steel) can be used. When a material other than the above-described conductive material is used, for example, a multi-layered structure of dissimilar metals such as iron coated with Al may be used. From the viewpoint of high electrical conductivity and good stability in the electrolytic solution, the current collector is preferably C, Ti, Cr, Au, Al, stainless steel or the like, and C from the viewpoint of oxidation resistance and material cost. Al, stainless steel and the like are preferable. More preferably, carbon-coated stainless steel is preferred.

  The shape of the current collector includes linear, rod-like, plate-like, foil-like and porous shapes. Among them, the packing density can be increased and the permeability of alkali metal ions is good during pre-doping treatment. The porous shape is preferred. Examples of the porous shape include a mesh, a woven fabric, a nonwoven fabric, an embossed body, an expanded body, and a foamed body. Among these, the shape of the current collecting base material is preferably an embossed body because of excellent output characteristics.

(Negative electrode)
In the present invention, the negative electrode is not particularly limited as long as it is a negative electrode used in a non-aqueous secondary battery.

  The negative electrode active material is not particularly limited as long as it is a material capable of reversibly inserting and extracting lithium. For example, Li, NA, K, C, Mg, Al, Si, P, K, CA, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, GA, Ge, Y, Zr, At least one element selected from the group consisting of Nb, Mo, Pd, Ag, Cd, In, Sn, Sb, W, Pb and Bi, an alloy, oxide, chalcogenide or halide using these elements If it is.

Among these, Li, NA, K, C, Mg, Al, Si, Ti, Zn, Ge, Ag, Cu from the viewpoint that the region of the discharge plateau can be observed within the range of 0 to 1 V (vs. lithium potential). At least one element selected from the group consisting of In, Sn and Pb, and an alloy or oxide using these elements are preferred. Further, from the viewpoint of energy density, the element is preferably Al, Si, Zn, Ge, Ag, Sn, or the like, and the alloy is Si—Al, Al—Zn, Si—Mg, Si—La, Al—Ge, Each combination of Si—Ge, Si—Ag, Si—Sn, Si—Ti, Zn—Sn, Ge—Ag, Ge—Sn, Ge—Sb, Ag—Sn, Ag—Ge, Sn—Sb, etc. is preferable. As the oxide, CuO, NiO, Li ₄ Ti ₅ O _{12 and the} like are preferable.
Two or more kinds of materials capable of reversibly occluding and releasing lithium may be used.

  The material capable of reversibly occluding and releasing lithium is more preferably a substance capable of occluding and releasing lithium ions and a compound that decomposes into a solid electrolyte during the initial charging process.

The solid electrolyte is not particularly limited as long as it is a substance having ionic conductivity, but is preferably a solid electrolyte represented by Li _α X _β Y _γ . In the formula, 0 <α ≦ 4, 0 ≦ β ≦ 2, and 0 ≦ γ ≦ 5. The solid electrolyte also serves as a buffer material that can reversibly store and release lithium.

However, X is at least one of Si, Ti, Mg, CA, Al, V, Ge, Zr, Mo, and Ni, and Y is O, S, F, Cl, Br, I, P, B It is one or more of ₂ O ₃ , C ₂ O ₄ , CO ₃ , PO ₄ , S, CF ₃ SO ₃ , SO ₃ .

More _{specifically, LiF, LiCl, LiBr, LiI} , Li 3 N, LiPON, Li 2 C 2 O 4, Li 2 CO 3, LiAlCl 4, Li 2 O, Li 2 S, LiSO 4, Li 2 SO 4 , Li ₃ PO ₄ , Li ₃ VO ₄ , Li ₄ GeO ₄ , Li ₂ Si ₂ O ₅ , Li ₂ SiO ₃ , Li ₄ SiO ₄ , Li ₄ ZrO ₄ , LiMoO ₄ , LiAlF ₄ , Li ₃ Ni ₂ , LiBF ₄ , LiCF ₃ SO _{3 and the} like, and one or more of these can be used.

Examples of the compound capable of absorbing and releasing alkali metal ions and the compound that decomposes into a solid electrolyte include, for example, SiO, GeO, GeS, GeS ₂ , SnO, SnO ₂ , SnC ₂ O ₄ , SnO—P ₂ O ₅ , SnO—B ₂ O ₃ , SnS, SnS ₂ , Sb ₂ S ₃ , SnF ₂ , SnCl ₂ , SnI ₂ , SnI _{4 and the} like may be used, and two or more of these may be used.

However, a substance capable of occluding and releasing alkali metal ions and a compound capable of decomposing into a solid electrolyte need to be pre-doped before assembling the battery because the battery capacity will be drastically reduced unless pre-doping is performed. .
The conductive aid for the negative electrode is not particularly limited as long as it has electronic conductivity, and the above-described metals, carbon materials, conductive polymers, conductive glass, and the like can be used.

  When the total of the active material, binder, and conductive additive contained in the negative electrode is 100% by mass, it is preferable that 0 to 20% by mass of the conductive additive is contained. That is, the conductive auxiliary agent is contained as necessary. When it exceeds 20 mass%, since the ratio of the active material as a battery is small, an electrode capacity density tends to become low.

  The negative electrode binder is not particularly limited as long as it is normally used. However, when an alloy-based negative electrode active material is used, the volume change of the active material accompanying charge / discharge is suppressed, and the cycle life characteristics of the battery are improved. From the viewpoint, PI is preferable.

  When the total of the active material, binder, and conductive additive contained in the negative electrode is 100% by mass, the binder is preferably contained in an amount of 2-30% by mass, more preferably 10-20% by mass.

  When the binder is less than 2% by mass, the electrode has low mechanical strength, so that the active material is easily removed, and the cycle life characteristics of the battery are deteriorated. On the other hand, when the content exceeds 30% by mass, the alkali metal ion conductivity is low, the electrical resistivity is too high, the pre-doping process takes time, and the ratio of the active material as the battery is small. Tends to be low.

  The current collector used for the negative electrode is not particularly limited as long as it is a material that has electronic conductivity and can conduct electricity to the held negative electrode active material. For example, conductive materials such as C, Ti, Cr, Ni, Cu, Mo, Ru, Rh, TA, W, Os, Ir, Pt, Al, Au, and alloys containing two or more of these conductive materials ( For example, stainless steel) can be used. When a material other than the above-described conductive material is used, for example, it may be a multi-layered structure of dissimilar metals such as iron coated with Cu or Ni.

  From the viewpoint of high electrical conductivity and good stability in the electrolytic solution, the current collector is preferably C, Ti, Cr, Au, Fe, Cu, Ni, stainless steel, etc., and further has reduction resistance and material cost. From the viewpoint, C, Cu, Ni, stainless steel and the like are preferable. More preferably, stainless steel is preferred. Moreover, since the alloy-type negative electrode has a large volume change of the nonpolar material accompanying charging and discharging, the current collecting base material is preferably stainless steel or iron. In addition, when using iron for a current collection base material, in order to prevent oxidation of the current collection base material surface, it is preferable that it is what was coat | covered with Ni or Cu.

  The shape of the current collector includes a linear shape, a rod shape, a plate shape, a foil shape, a net shape, a woven fabric, a nonwoven fabric, an embossed body, an expanded body, a porous body, or a foamed body, and among these, the packing density can be increased, In the pre-doping treatment, an embossed body, an expanded body, a porous body or a foamed body is preferable because the alkali metal ion permeability is good. More preferably, an embossed body is preferable because of excellent output characteristics.

(Manufacture of electrodes)
A method for producing an electrode is to mix an active material, a binder, and a conductive additive added as necessary, and apply a slurry to a current collector, temporarily dry it, and then perform a heat treatment. The method of obtaining an electrode can be mentioned. As a method for manufacturing a supplementary electrode, a supplementary material, a binder, and a conductive additive added as necessary are mixed, and the slurry is applied to a current collector and temporarily dried. A method for obtaining an electrode by performing a heat treatment can be mentioned.

The temporary drying is not particularly limited as long as the solvent in the slurry can be volatilized and removed, and examples thereof include a method of performing a heat treatment in the atmosphere at a temperature of 50 to 200 ° C.
Said heat processing can be performed by hold | maintaining at 50-400 degreeC under reduced pressure for 0.5 to 50 hours.

(Separator)
As a separator, what is generally used for a non-aqueous secondary battery can be used.
Examples of the shape of the separator include microporous membranes, woven fabrics, non-woven fabrics, and green compacts. Among these, non-woven fabrics are preferable from the viewpoints of alkali metal ion permeability, battery output characteristics, and manufacturing costs.
The material of the separator is not particularly limited, but preferably contains a heat-resistant resin that does not melt down due to local heat generation during a short circuit.

Examples of the heat resistant resin include ceramics such as SiO ₂ , ZrO, Al ₂ O ₃ , B ₂ O ₃ , MgO, CAO, BN, and SiC. Moreover, the separator which coat | covered the ceramic to the existing separator and improved heat resistance may be sufficient.

The porosity of the separator is not particularly limited as long as it is 50% or more, but is preferably 70% or more and 95% or less from the viewpoint of alkali metal ion conductivity. The air permeability obtained by the Gurley test method is preferably 300 sec / 100 cc or less.
Here, the porosity is a value calculated by the following equation from the apparent density of the separator and the true density of the solid content of the constituent material.
Porosity (%) = 100− (apparent density of separator / true density of solid material content) × 100
The Gurley air permeability is an air resistance according to a Gurley tester method defined in JIS P 8117.

<Description of pre-dope>
(Supplementary electrode)
The filling electrode is an electrode for pre-doping the positive electrode or the negative electrode, and is an electrode having alkali metal ions as a filling material. Specifically, A, ACoO ₂ , ANiO ₂ , ANi 0.33 Mn 0.33 Co 0.33 O ₂ , AMnO ₂ , AMn ₂ O ₄ , AFePO ₄ , AFe0.5Mn0.5PO ₄ , AMnPO ₄ , ANb ₂ O ₅ , ANbO ₂ , AFeO ₂ , AMgO ₂ , ACAO ₂ , ATiO ₂ , ATiS ₂ , ACrO ₂ , ARuO ₂ , ACuO ₂ , AZnO ₂ , AMoO ₂ , AMoS ₂ , ATAO ₂ , AWO ₂ , AV ₂ O ₅ , AVO ₂ , AC 6, A ₃ Al, A ₄ Si, A ₄ Al It is an electrode containing Ge, A ₃ Ag, ACu 0, ANiO, A _{3 In} , A ₄ Sn, APb, and the like. Here, A is a group 1 element of the periodic table and represents an alkali metal element, specifically, Li, NA, or K.

Of these, the supplementary electrode using A can be pre-doped most easily because it has alkali metal ions. However, since it is easily oxidized and deteriorated at a high temperature of 45 ° C. or higher, AFePO ₄ , AFe0.5Mn0.5PO ₄ , AMnPO ₄ , AV ₂ O ₅ , AVO ₂ , A ₄ Si, and A ₄ Sn are stable even in a high temperature pre-dope solution. A ₄ Ge, ACuO, and ANiO are preferable. In particular, AV ₂ O ₅ , AVO ₂ , A ₄ Si, and A ₄ Sn having a relatively large amount of alkali metal ions are more preferable.

  However, when using a filling material that does not have an A component, A is filled using techniques such as (1) alkali metal thin film pasting doping, (2) electrochemical doping, and (3) mechanical doping described above. May be.

  For example, when Si is used for a filling material that does not have an A component, (1) Alkali metal thin film sticking doping provides a filling electrode by sticking an alkali metal thin film to the surface of the Si electrode. (2) In electrochemical doping, a half electrode using an alkali metal for the Si electrode and its counter electrode is prepared and a voltage is applied to obtain a supplementary electrode. (3) In a technique such as mechanical doping, Si powder and A are supplemented by mechanical milling using a planetary ball mill or the like to obtain A supplemented Si powder, which is used to make an electrode. An electrode is obtained.

  When the non-aqueous secondary battery is a lithium ion secondary battery, a lithium polymer battery, a solid lithium battery, or the like, it is preferable that A is Li. In the case of a sodium ion secondary battery, a polymer sodium battery, a solid sodium battery, a sodium-sulfur battery, or the like, A is preferably Na.

  The filling electrode may contain a conductive aid as necessary. The conductive aid is not particularly limited as long as it has electronic conductivity, and the above-described metals, carbon materials, conductive polymers, conductive glass, and the like can be used.

  When the total of the filling material, the binder, and the conductive auxiliary agent contained in the auxiliary electrode is 100% by mass, the conductive auxiliary agent is preferably contained in an amount of 0 to 30% by mass. That is, the conductive auxiliary agent is contained as necessary. When it exceeds 30 mass%, a conductive support agent will fall in the liquid for pre dope, and it will become difficult to fully obtain the effect of a pre dope process.

The supplementary electrode binder may be any of those usually used as described above, but PI is preferable from the viewpoint that it does not easily swell in a high temperature pre-doping solution.
When the total of the active material, binder, and conductive additive contained in the filling electrode is 100% by mass, the binder is preferably contained in an amount of 2-40% by mass.

  If the binder is less than 2% by mass, the mechanical strength of the electrode is low, so that the filling material and the conductive auxiliary agent are easily dropped into the pre-doping solution, and the effect of the pre-doping treatment is hardly obtained. On the other hand, if it exceeds 40% by mass, the alkali metal ion conductivity is low and the electrical resistivity is too high, and the pre-doping process takes time.

The current collector used for the supplementary electrode is not particularly limited as long as it is a material that has electronic conductivity and can conduct electricity to the retained supplementary material. For example, conductive materials such as C, Ti, Cr, Ni, Cu, Mo, Ru, Rh, TA, W, Os, Ir, Pt, Al, Au, and alloys containing two or more of these conductive materials, For example, stainless steel can be used.
The shape of the current collecting substrate includes a linear shape, a rod shape, a plate shape, a foil shape, and a porous shape. Among these, the porous shape described above is preferable because the packing density can be increased.

(Pre-dope solution)
The pre-doping liquid may be any liquid that can move alkali metal ions from the filling electrode to the filling target electrode (positive electrode or negative electrode). The liquid of the same component as the electrolyte solution used for the battery mentioned later may be sufficient. Usually, an electrolytic solution used for a battery is used in a state where an electrolyte is dissolved in a solvent.

  Since it is necessary to contain an alkali metal ion as an electrolyte, the electrolyte salt is not particularly limited as long as it is used in a non-aqueous secondary battery, but an alkali such as a lithium salt, a sodium salt, a potassium salt, etc. Metal salts are preferred. Examples of the alkali metal salt include lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, lithium trifluoromethanesulfonate, sodium hexafluorophosphate, sodium perchlorate, tetrafluoro Group consisting of sodium borate, sodium trifluoromethanesulfonate and sodium trifluoromethanesulfonate, potassium hexafluorophosphate, potassium perchlorate, potassium tetrafluoroborate, potassium trifluoromethanesulfonate and potassium trifluoromethanesulfonate imide At least one selected from the above can be used.

  As the electrolyte solvent, at least one selected from the group consisting of propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, and γ-butyrolactone can be used, and in particular, propylene carbonate, a mixture of ethylene carbonate and diethyl carbonate. Or γ-butyrolactone is preferred.

Examples of the solvent for the electrolyte include propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), γ-butyrolactone, 2-methyltetrahydrofuran, 1,3-dioxolane, 4- At least selected from the group consisting of methyl-1,3-dioxolane, 1,2-dimethoxyethane, 1,2-diethoxyethane, diethyl ether, sulfolane, methyl sulfolane, nitromethane, N, N-dimethylformamide, dimethyl sulfoxide One type can be used, and propylene carbonate, a mixture of ethylene carbonate and diethyl carbonate, or γ-butyrolactone is particularly preferable. The mixing ratio of the mixture of ethylene carbonate and diethyl carbonate can be arbitrarily adjusted within a range of 10 to 90% by volume for both ethylene carbonate and diethyl carbonate.
Moreover, an ionic liquid, molten salt, etc. may be sufficient.

  However, the pre-doping solution can be used at room temperature, but is preferably used in a temperature range of 45 to 300 ° C. 50-250 degreeC is more preferable, and it is still more preferable to use at 60-180 degreeC. By making it into said temperature range, the ion conductivity of the liquid for pre dope and the ion diffusibility of a positive electrode or a negative electrode can be improved dramatically, and the pre dope process of a battery can be performed effectively. Moreover, the gas generation in a battery can be suppressed by performing the generation | occurrence | production of the gas accompanying charging / discharging in the process of a pre dope process previously.

  Therefore, it is preferable that the pre-doping liquid is a liquid that hardly evaporates and has heat resistance. Therefore, as an electrolyte, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, lithium trifluoromethanesulfonate imido, sodium tetrafluoroborate, sodium trifluoromethanesulfonate and sodium trifluoromethanesulfonate, potassium tetrafluoroborate, Preference is given to potassium trifluoromethanesulfonate and potassium trifluoromethanesulfonateimide.

  As the electrolyte solvent, at least one selected from the group consisting of propylene carbonate, ethylene carbonate, and γ-butyrolactone can be used, and in particular, propylene carbonate, a mixture of ethylene carbonate and γ-butyrolactone is preferable. From the viewpoint of evaporating easily at a temperature of 80 ° C. or higher, an ionic liquid or a molten salt is preferably used, and an ionic liquid that can be used at room temperature is more preferable. An ionic liquid or a molten salt can be used for a long period of time because it eliminates the risk of vapor ignition during pre-doping and does not have vapor pressure.

  Ionic liquids and molten salts are classified into pyridine type, alicyclic amine type, aliphatic amine type, etc., depending on the type of cation (cation). Various ionic liquids or molten salts can be synthesized by selecting the type of anion (anion) to be combined therewith. Cations used include ammonium-based, phosphonium-based and non-ionic ions such as imidazolium salts and pyridinium salts. Examples of anions used include halogen-based bromide ions and triflate, boron-based tetraphenylborate, There are phosphorus-based materials such as hexafluorophosphate.

The ionic liquid or molten salt is composed of, for example, a combination of a cation such as imidazolinium and an anion such as Br ⁻ , Cl ⁻ , BF ₄ ⁻ , PF ₆ ⁻ or (CF ₃ SO ₂ ) 2N ^−. It can be obtained by a known synthesis method.

  In the case of an ionic liquid or molten salt, an electric current can be passed without adding an electrolyte, and the potential window is wide. Although depending on the type of ionic liquid, the liquid state is maintained even in the temperature range of −30 to 300 ° C., there is little change in physical properties, and heat resistance is high. Further, the vapor pressure is extremely low, it is non-volatile, and it is economical because it can be easily separated and reused after a chemical reaction.

  Although depending on the type of ionic liquid and molten salt, they do not dissolve in water or organic solvents, so even if they are mixed with these, phase separation occurs, preventing deactivation of electrode materials due to moisture. There is also an effect. Moreover, since the thermal conductivity is excellent, the effect of diffusing the reaction heat generated during the pre-doping is also excellent.

  However, ionic liquids and molten salts, unlike the electrolytes used in ordinary batteries, have high liquid viscosities, so the batteries may not be fully pre-doped. From the viewpoint of enhancing conductivity, the temperature of the liquid is preferably 45 to 300 ° C. 50-250 degreeC is more preferable, and it is still more preferable to use at 60-180 degreeC.

(Pre-doping method)
A battery is manufactured using the positive electrode, the negative electrode, and the separator described above, and includes a supplementary electrode serving as an alkali ion source arranged so as not to be in contact with the positive electrode and the negative electrode. Alkaline metal ions are electrochemically applied to the positive electrode or the negative electrode by being immersed in the pre-dope solution in a state of being arranged in a direction perpendicular to the negative electrode surface, and applying a voltage to the positive electrode or the negative electrode and the supplementary electrode. Can be compensated.

  By arranging the filling electrode in a direction perpendicular to the positive electrode surface and the negative electrode surface, alkali metal ions diffuse along the electrode surface of the laminated body or the wound body, so that the pre-doping can be uniformly processed. it can. For example, when the compensating electrode is arranged in parallel to the positive electrode surface and the negative electrode surface, only the electrode layer in the vicinity of the compensating electrode facing the laminated body or the wound body is pre-doped, resulting in nonuniformity. Cheap.

  The filling electrode is preferably at least larger than the electrode capacity to be filled, and has a larger surface area than the cross-sectional area of the laminated body or the wound body. Thereby, the pre-doping process excellent in uniformity becomes possible.

  After immersion in the pre-doping solution, if short-circuiting is not applied to the positive electrode or the negative electrode to the filling electrode, alkali metal ions move from the filling electrode and the positive or negative electrode is pre-doped. Therefore, it is preferable to apply a voltage. The voltage to be applied varies depending on the type of filling material used for the filling electrode, but may be a voltage at which alkali metal ions move.

  The current density at this time is preferably a current density at which the capacity of the electrode to be compensated can be discharged or charged in 1 minute to 100 hours. More preferably, it is 1 hour-50 hours, and it is still more preferable that it is 2 hours-20 hours.

  Furthermore, it is preferable to insert and desorb alkali metal ions from the electrode after filling treatment to the filling electrode at the above current density. Thereby, the pre-doping process excellent in uniformity can be performed, the gas generated at the time of charging / discharging of the battery is released in advance, and the generation of gas in the battery can be suppressed.

<Non-aqueous secondary battery and pre-dope>
The electrode (positive electrode or negative electrode) thus obtained is joined to a counter electrode (negative electrode or positive electrode) via a separator, and sealed in a state of being immersed in an electrolytic solution to form a secondary battery. According to the non-aqueous secondary battery subjected to the above-mentioned pre-doping treatment, it is possible to function as a non-aqueous secondary battery that has both a high capacity and a long life and generates less gas in the battery.
The structure of the non-aqueous secondary battery is not particularly limited, but can be applied to existing battery forms and structures such as a stacked battery and a wound battery.
A wound battery 31 shown in FIG. 1 mainly includes a positive electrode 33, a negative electrode 34, a separator 35, and an electrolytic solution disposed in a battery case 32. The battery case 32 is a substantially cylindrical container having an opening 32a in the upper part, and the bottom part thereof is set as a negative electrode terminal. The strip-shaped positive electrode 33 and the negative electrode 34 are arranged in the battery case 32 in a state of being wound in a spiral shape with the separator 35 interposed therebetween. Further, the opening 32 a of the battery case is sealed in a liquid-tight manner by the sealing plate 37 in a state where the electrolyte is injected into the battery case 32. The cap 36 provided on the upper surface of the sealing plate 37 serves as a positive electrode terminal. The positive electrode terminal is connected to the positive electrode 33 by a lead wire (not shown).

  A laminated battery 41 shown in FIG. 2 includes a first electrode 43 which is either a positive electrode or a negative electrode and is in contact with and electrically connected to an inner surface 42a of a cylindrical outer body 42, and the other electrode. And a second electrode 44 that is not in contact with the inner surface 42a of the exterior body 42, and a rod-shaped conductive current collecting rod 47 penetrates the positive electrode, the negative electrode, and the separator 45 in the axial direction of the exterior body 42. The second electrode 44 is in contact with and electrically connected to the current collecting rod 47, and the first electrode 43 is not in contact with the current collecting rod 47.

  Place the electrode and the compensation electrode so that they are not in contact with each other, and immerse them in the pre-dope solution in a state where the compensation electrode is arranged in a direction perpendicular to the electrode surface, and apply a voltage between the electrode and the compensation electrode. Is applied to electrochemically fill the electrode with alkali metal ions.

  The non-aqueous secondary battery according to the present invention may be a lithium ion secondary battery, a lithium polymer battery, a solid lithium battery, a sodium ion secondary battery, a polymer sodium battery, a solid sodium battery, a sodium-sulfur battery, or the like. Among these, it is preferable that it is a lithium ion secondary battery from a viewpoint of the voltage and capacity | capacitance in a single battery.

<Test result 1>
The test results of the first embodiment (winding type) will be described.
(Example 1)
Using SiO as the negative electrode active material, 80% by mass of the negative electrode active material, 2% by mass of AB, and 18% by mass of PI binder were mixed to prepare a slurry mixture, which was applied and dried on both sides of a stainless steel foil having a thickness of 20 μm. After that, the stainless steel foil (current collecting base material) and the coating film (negative electrode active material layer) were closely bonded with a roll press machine, and then heat-treated (during decompression, at 350 ° C. for 1 hour or more) to form the negative electrode ( A single-sided electrode capacity of 2.9 mAh / cm 2 was obtained.
For the positive electrode, LiFePO ₄ was used as the positive electrode active material, and 92% by mass of the positive electrode active material, 3% by mass of AB, and 5% by mass of the PI binder were mixed to prepare a slurry mixture. After coating and drying, the aluminum press foil (current collecting base material) and the coating film (positive electrode active material layer) are closely bonded with a roll press machine, and then heat treatment (at 245 ° C. for 1 hour or more in a reduced pressure) Thus, a positive electrode (single-sided electrode capacity of 1.4 mAh / cm 2) was obtained.

  The filling electrode uses Si as a filling material, and mixes 75% by weight of the filling material, 4% by weight of AB, 1% by weight of VGCF, and 20% by weight of PI binder to prepare a slurry mixture, and has a foam thickness of 500 μm. -After filling and drying the nickel alloy, the foamed chrome-nickel alloy (current collector base material) and the coating film (complementary material layer) are tightly bonded with a roll press, and then heat treatment (under reduced pressure, 350 ° C, 1 hour or more), and a metal lithium foil having a thickness of 300 μm was pressure-bonded to obtain a filling electrode (electrode capacity: 50 mAh / cm 2). In addition, the electrode for filling has a surface area of 5 times or more than the cross-sectional area of the wound body.

Using the negative electrode and the positive electrode obtained above, a polypropylene nonwoven fabric having a thickness of 20 μm and a wound body having a nominal capacity of about 1 Ah were prepared as a separator. The filling electrode is arranged (vertical direction) so that the alkali metal ions diffuse along the positive electrode surface and the negative electrode surface so as not to contact the positive electrode and the negative electrode of the obtained wound body, and the temperature is 80 ° C. It was immersed in the pre-dope solution. FIG. 3A shows the arrangement of pre-doped electrodes in Example 1. FIG. An electrode body composed of the negative electrode 2, the positive electrode 1, and the separator 3 interposed therebetween is submerged in the pre-doping tank 9 filled with the pre-doping solution 5, and the compensating electrode 4 is disposed in the pre-doping tank 9 as a counter electrode. A DC power supply 8 is connected between the compensation electrode 4 and the negative electrode tab 7 provided on the negative electrode 1, and wiring is performed so that a current flows from the compensation electrode 4 toward the negative electrode 2. The lithium ions Li ^{+ in the} pre-doping solution 5 are supplied to the negative electrode 2 and the negative electrode 2 is pre-doped. On the other hand, lithium in the filling electrode 4 is eluted into the pre-doping solution 5 to supply lithium ions to the pre-doping solution 5. Next, as shown in FIG. 3B, the wiring 10 is changed from the negative electrode tab 7 to the positive electrode tab 6 provided on the positive electrode 1, and the DC power supply 8 is connected to the positive electrode 2, whereby the positive electrode 2 is pre-doped. . In FIG. 3, the direction of the current flowing through the pre-doping solution 5 is along the electrode surface. That is, since the polarity of the DC power supply 8 is in the direction along the electrode surface, lithium ions are uniformly pre-doped on the electrode.

As the pre-doping solution, an ionic liquid (a solution obtained by dissolving 1 mol / kg LiTFSI in ethylmethylimidazolium / bis (fluorosulfonyl) imide anion) was used.
The negative electrode and the filling electrode were subjected to 5 cycles under the conditions of a voltage cut-off of 0-1 V (vs. Li + / Li) and a current of 100 mA (0.05 C rate with respect to the negative electrode capacity), and the negative electrode was 1 V (vs. Li + / Li). The pre-doping process was performed so as to be in the state of
Thereafter, the wound body is put in an aluminum laminate cell, 1 mol / L LiPF6 / EC: DEC (1: 1 vol%) is added as an electrolytic solution, and it is heat-bonded and sealed in a vacuum, and has a nominal capacity of about 1 Ah. A wound laminate cell was obtained.

(Example 2)
Example 2 is the same as Example 1 except that the separator used is a microporous polypropylene membrane having a thickness of 20 μm.
(Example 3)
Example 3 is the same as Example 1 except that an aramid nonwoven fabric having a separator thickness of 20 μm was used.
Example 4
Example 4 is the same as Example 3 except that the temperature of the pre-dope solution is changed to 20 ° C.
(Example 5)
Example 5 is the same as Example 3 except that the temperature of the pre-dope solution is changed to 150 ° C.
(Example 6)
Example 6 is the same as Example 3 except that metallic lithium is used for the filling electrode.
(Example 7)
Example 7 is the same as Example 3 except that graphite is used for the filling electrode.
(Example 8)
Example 8 is the same as Example 3 except that SnO is used for the filling electrode.
Example 9
Example 9 is the same as Example 3 except that an embossed aluminum metal foil is used for the positive electrode current collector.
(Example 10)
Example 10 is the same as Example 9 except that an embossed stainless steel foil was used for the negative electrode current collector.

(Comparative Example 1)
Comparative Example 1 is the same as Example 3 except that no pre-doping treatment was performed.
(Comparative Example 2)
Comparative Example 2 is the same as Example 3 except that the position of the filling electrode is arranged in parallel with the positive electrode surface and the negative electrode surface of the wound body. In FIG. 4, each electrode arrangement of the pre-dope performed in Comparative Example 2 is shown. The difference from FIG. 3 is that the direction of the current flowing through the pre-doping solution 5 is perpendicular to the electrode surface. That is, the polarity of the DC power supply 8 is perpendicular to the electrode surface.

(Charge / discharge test)
The battery cycle test was conducted on the wound batteries of Examples 1 to 10 and Comparative Examples 1 and 2 under a 30C atmosphere under charge / discharge conditions of 0.5C rate charge / discharge and 4-2V cut-off. Table 1 shows the cycle characteristics of the battery.
As can be seen from Table 1, the battery subjected to the pre-doping treatment has a larger initial discharge capacity than the battery not subjected to the pre-doping treatment (Comparative Example 1). In addition, the pre-doped battery in which the position of the filling electrode is arranged perpendicularly to the positive electrode surface and the negative electrode surface of the wound body is more initial than the battery arranged in parallel (Comparative Example 2). Large capacity.
From the results of Examples 1 to 3, it was found that the separator structure is a non-woven fabric rather than a microporous film, thereby improving the initial discharge capacity.

From the results of Examples 3 to 5, it has been found that the temperature of the pre-doping solution is 80 ° C. or higher, thereby improving the initial discharge capacity and cycle life characteristics.
From the results of Examples 3 and 6 to 8, the filling electrode is not easily operated with graphite, and even with metallic lithium, the initial discharge capacity and the cycle life characteristics are not sufficient as compared with the filling electrode using Si or SnO. . This is presumably because graphite and metallic lithium deteriorate with the pre-doping solution at 80 ° C.
From the results of Examples 3, 9, and 10, the current collecting base material used for the positive electrode and the negative electrode is a current collecting base material embossed rather than the foil-like material, so that the initial discharge capacity and cycle life characteristics are obtained. It has been found that there is an effect of improving. This is presumably because the ion permeability of the electrode was improved by embossing, and the pre-doping treatment was performed uniformly.

<Test result 2>
The test results of the second embodiment (stacked type) will be described.
(Example 11)
Using SiO as the negative electrode active material, 80% by mass of the negative electrode active material, 2% by mass of AB, and 18% by mass of PI binder were mixed to prepare a slurry mixture, which was applied and dried on both sides of a stainless steel foil having a thickness of 20 μm. After that, the stainless steel foil (current collecting base material) and the coating film (negative electrode active material layer) were closely bonded with a roll press machine, and then heat-treated (during decompression, at 350 ° C. for 1 hour or more) to form the negative electrode ( A single-sided electrode capacity of 2.9 mAh / cm2) was obtained.
For the positive electrode, LiFePO ₄ was used as the positive electrode active material, and 92% by mass of the positive electrode active material, 3% by mass of AB, and 5% by mass of the PI binder were mixed to prepare a slurry mixture. After coating and drying, the aluminum press foil (current collecting base material) and the coating film (positive electrode active material layer) are closely bonded with a roll press machine, and then heat treatment (at 245 ° C. for 1 hour or more in a reduced pressure) Thus, a positive electrode (single-sided electrode capacity of 1.4 mAh / cm 2) was obtained.
The filling electrode uses Si as a filling material, and mixes 75% by weight of the filling material, 4% by weight of AB, 1% by weight of VGCF, and 20% by weight of PI binder to prepare a slurry mixture, and has a foam thickness of 500 μm. -After filling and drying the nickel alloy, the foamed chrome-nickel alloy (current collector base material) and the coating film (complementary material layer) are tightly bonded with a roll press, and then heat treatment (under reduced pressure, 350 ° C, 1 hour or more), and a metal lithium foil having a thickness of 300 μm was pressure-bonded to obtain a filling electrode (electrode capacity: 50 mAh / cm 2). The supplementary electrode has a surface area that is five times or more than the cross-sectional area of the laminate.
Using the negative electrode and the positive electrode obtained above, a polyimide nonwoven fabric having a thickness of 20 μm and a wound body having a nominal capacity of about 1 Ah were produced as a separator.

Arrange the supplementary electrodes so that the alkali metal ions diffuse along the positive electrode surface and the negative electrode surface (vertical direction) so that they are not in contact with the positive electrode and negative electrode of the obtained laminate, and the temperature is 65 ° C. It was immersed in a pre-dope solution. FIG. 5 shows each electrode arrangement of pre-doping performed in Example 11. The operation is the same as in FIG. As in FIG. 3, the direction of the current flowing through the pre-doping solution 5 is a direction along the electrode surface. That is, the polarity of the DC power supply 8 is in a direction along the electrode surface.
As the pre-dope solution, an organic electrolytic solution (a solution in which 1 mol / L LiPF ₆ was dissolved in PC: EC: DEC (= 50: 25: 25 vol.%)) Was used.
The positive electrode and the supplementary electrode were subjected to 5 cycles under conditions of a voltage cut-off of 0-1 V (vs. Li + / Li) and a current of 100 mA (0.05 C rate with respect to the negative electrode capacity), and the negative electrode was 1 V (vs. Li + / Li). Pre-doping treatment was performed so as to be in the state of Li).
Thereafter, the wound body is put in an aluminum laminate cell, 1 mol / L LiPF ₆ / EC: DEC (1: 1 vol%) is added as an electrolytic solution, heat-press sealed in a vacuum, and a nominal capacity of about 1 Ah. A laminated laminate cell was obtained.

(Comparative Example 3)
Comparative Example 3 is the same as Example 11 except that no pre-doping treatment was performed.
(Comparative Example 4)
Comparative Example 4 is the same as Example 11 in which the position of the filling electrode is arranged in parallel to the positive electrode surface and the negative electrode surface of the multilayer body. FIG. 6 shows the arrangement of the pre-doped electrodes performed in Comparative Example 4. The difference from FIG. 5 is that the direction of the current flowing through the pre-doping solution 5 is perpendicular to the electrode surface. That is, the polarity of the DC power supply 8 is perpendicular to the electrode surface.

(Charge / discharge test)
Example 11 A battery cycle test was conducted on a laminated battery in a 30 ° C. atmosphere under charge / discharge conditions of 0.5C rate charge / discharge and 4-2V cut-off. Table 2 shows the cycle characteristics of the battery.
As can be seen from Table 2, the battery subjected to the pre-doping treatment has a larger initial discharge capacity than the battery not subjected to the pre-doping treatment (Comparative Example 3). In addition, the pre-doped battery in which the position of the filling electrode is arranged perpendicular to the positive electrode surface and the negative electrode surface of the laminate is higher than the initial discharge capacity in comparison with the battery arranged in parallel (Comparative Example 4). Is big.

  The non-aqueous secondary battery obtained by the present invention can be used for applications such as a main power source for mobile communication devices, portable electronic devices, electric bicycles, electric motorcycles, electric vehicles, and the like.

DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Negative electrode 3 Separator 4 Supplementary electrode 5 Pre-doping liquid 6 Negative electrode tab 7 Positive electrode tab 8 DC power supply 9 Pre-doping tank 10 Wiring 31 Winding battery 32 Battery case 33 Positive electrode 34 Negative electrode 35 Separator 36 Cap 37 Sealing plate 41 Stacked battery 42 Exterior body 43 First electrode 44 Second electrode 45 Separator 47 Current collecting rod

Claims (10)

A pre-doping method for a non-aqueous secondary battery having a positive electrode and a negative electrode,
Arranging a supplementary electrode having an alkali metal ion source arranged so as not to contact the positive electrode and the negative electrode so as to be immersed in a pre-doping solution from which alkali metal ions are eluted,
A DC power source is connected between one of the positive electrode or the negative electrode and the compensation electrode, and the direction of the electric field generated by the DC power source is the same as the direction of the electrode surface of the battery electrode. Pre-doping method for secondary battery.   The pre-doping method for a non-aqueous secondary battery according to claim 1, wherein an electrode capacity of the filling electrode is larger than an electrode capacity of the electrode, and a surface area of the filling electrode is larger than a cross-sectional area of the electrode.   The pre-doping method for a non-aqueous secondary battery according to claim 1, wherein the pre-doping solution is 45 to 300 ° C. 3.   The pre-doping method of the non-aqueous secondary battery which has the process of charging / discharging between the said positive electrode and the said negative electrode after the pre dope as described in any one of Claims 1-3.   The pre-doping method for a non-aqueous secondary battery according to claim 1, wherein the pre-doping solution is an ionic liquid containing an alkali metal salt.   The pre-doping method for a non-aqueous secondary battery according to claim 1, wherein the negative electrode is a negative electrode using a metal, an alloy, or a compound containing an element of Si or Sn.   The pre-doping method for a non-aqueous secondary battery according to any one of claims 1 to 6, wherein the current collecting base material is made of a material using steel or stainless steel.   The positive electrode or the positive electrode is an electrode using a thermosetting resin having heat resistance as a binder, and the total of the active material, binder and conductive additive contained in the positive electrode or the positive electrode is 100% by mass. In the case, the pre-doping method of the non-aqueous secondary battery according to any one of claims 1 to 7, wherein the binder is contained in an amount of 1 to 20% by mass.   A non-aqueous secondary battery obtained by the pre-doping method for a non-aqueous secondary battery according to claim 1.   An electric device using the non-aqueous secondary battery according to claim 9.

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