JP2006173000A - Method for manufacturing lithium polymer battery and battery obtained by the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithium polymer battery which can reduce an amount of gas generated in the first charging of batteries and to provide a method for manufacturing the same. <P>SOLUTION: The method is offered in which an electrode active material is degassed by performing a first charging/discharging (pre-charging/pre-discharging) in a condition of ink before being coated on a current collector foil. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a lithium polymer battery and a lithium polymer battery obtained thereby, and more particularly to a method for producing a high output type lithium polymer battery suitable as a motor drive power source for a fuel cell, a hybrid vehicle, etc. The present invention relates to a lithium polymer battery.

  Recently, in order to promote the introduction of electric vehicles (EV), hybrid vehicles (HEV), and fuel cell vehicles (FCV; including hybrid fuel cell vehicles) against the backdrop of the increasing environmental protection movement, these motor drive power supplies and hybrid Auxiliary power supplies are being developed. In such applications, lithium ion secondary batteries that can be repeatedly charged and discharged are used. In applications that require high output and high energy density, such as EV, HEV, and FCV motor drives, a single large battery cannot be made in practice, and an assembled battery composed of a plurality of batteries connected in series. It is common to use. As one battery constituting such an assembled battery, it has been proposed to use a thin laminate type lithium ion battery (see, for example, Patent Document 1).

  The basic configuration of one lithium ion battery constituting such an assembled battery is that a positive electrode and a negative electrode are arranged via a separator and filled with a non-aqueous electrolyte (liquid electrolyte).

Furthermore, there has been proposed a polymer electrolyte battery (polymer battery) produced by a method in which a positive electrode, a negative electrode, and a polymer electrolyte are overlapped using a polymer electrolyte that is less likely to cause a liquid junction phenomenon than the liquid electrolyte and has improved safety ( For example, see Patent Document 2.) Since the polymer battery does not easily leak to the outside of the battery, a highly safe battery can be formed.
JP2003-151526A JP 2002-305028 A

  In the conventional electric power described in Patent Documents 1 and 2, since the battery is assembled and charged after the electrode active material is applied to the current collector foil, it is necessary to remove the gas generated during the initial charge. It was.

  However, in the polymer battery as described in Patent Document 2, the gas generated once because the fluidity of the polymer solid electrolyte or polymer gel electrolyte (electrolyte solution in the polymer gel electrolyte) in the polymer electrolyte layer is low. It was difficult to remove. Therefore, there is a problem that the charge / discharge performance is deteriorated, for example, gas generated at the time of initial charge remains on the electrode surface, the electrode reaction area decreases, and the internal resistance increases.

  Accordingly, an object of the present invention is to provide a lithium polymer battery capable of reducing the amount of gas generated when the battery is initially charged, and a method for manufacturing the lithium polymer battery.

  The present invention can be achieved by a method for producing a lithium polymer battery, characterized in that initial charge / discharge is performed in an ink state before the electrode active material is applied to the current collector foil.

  In the lithium polymer battery and the method for producing the same of the present invention, the initial charge / initial discharge (hereinafter also referred to as precharge / predischarge) is performed in an ink or slurry state before the electrode active material is applied to the current collector foil. Thus, the gas generated during the initial charging can be generated and removed in advance. Therefore, it is possible to reduce the amount of gas generated when the battery is initially charged.

  At the same time, by reacting with the irreversible capacity site of the active material by using a Li ion supply source outside the active material by precharge / predischarge, the active material-derived Li ions are trapped at the irreversible capacity site and the reversible capacity is reduced. Can also be prevented. As a result, the amount of gas generated during the initial charge can be significantly reduced, and the high charge / discharge performance set during battery manufacture can be maintained over a long charge / discharge cycle without greatly reducing during the initial charge.

  The method for producing a lithium polymer battery according to the present invention is characterized in that pre-charging / pre-discharging is performed in an ink state before applying a negative electrode using an electrode active material, particularly amorphous carbon as an active material, to a current collector foil. To do. Thereby, the amount of gas generated at the time of initial charge can be reduced. In addition, when pre-charging / pre-discharging is performed with the electrode active material in a powder state, there is no problem as described below. (I) When initial charge / discharge is performed after forming an electrode on a conventional current collector, gas may accumulate between the current collector and the electrode. Therefore, there is no such problem. (Ii) When the initial charge / discharge is performed after forming an electrode on a conventional current collector, the volume efficiency is not good, but the volume efficiency is also increased because it is performed in a powder state.

  Hereinafter, the manufacturing method of the lithium polymer battery of the present invention will be described with reference to the drawings.

  FIG. 1 is a process flowchart of a representative embodiment (also referred to as a first embodiment) of a method for producing a lithium polymer battery of the present invention.

As shown in FIG. 1, in the manufacturing method according to the first embodiment of the lithium polymer battery of the present invention;
(1) As a positive electrode forming step, (i) a positive electrode pre-ink preparation step 101, (ii) a pre-charge / degassing / pre-discharge step 103 of the positive electrode pre-ink, and (iii) a cleaning / drying step 105 of the positive electrode pre-ink, (Iv) a positive ink preparation step 107, (v) a positive ink coating / drying / pressing / cutting step 109, and (vi) a pregel application step 111 on the positive electrode.

  Similarly, (2) the negative electrode forming step includes (i) a negative electrode pre-ink preparation step 121, (ii) a pre-charge / degassing / pre-discharge step 123 for the negative electrode pre-ink, and (iii) a cleaning / drying step for the negative electrode pre-ink. 125, (iv) a negative electrode ink preparation step 127, (v) a negative electrode application / drying / pressing / cutting step 129, and (vi) a pregel solution application step 131 to the negative electrode.

  Moreover, (3) As a formation process of a polymer electrolyte layer, it has (i) preparation process 141 of a pregel solution, and (ii) pregel application | coating process 143 to a separator.

  Next, (4) the battery manufacturing process includes (i) an assembly process 151 of a positive electrode, a negative electrode, and a polymer electrolyte layer, (ii) a recharging process 153, and (iii) an aging / inspection process 155. is there.

  Hereinafter, each process according to the first embodiment will be described in detail.

(1) Positive electrode formation step (i) Positive electrode pre-ink preparation step In the positive electrode pre-ink preparation step 101, among the components constituting the positive electrode, a positive electrode active material and a conductive material for enhancing electronic conductivity are mixed at a predetermined mixing ratio. Then, a necessary amount of electrolyte suitable for precharge / predischarge is added and suspended therein to prepare a positive electrode pre-ink. At this stage, it is better not to add other components constituting the positive electrode. In particular, when a viscosity adjusting solvent such as NMP is included, if the solvent is present in a state where a potential is applied, it reacts to generate gas, which hinders precharge / predischarge of the electrode active material. This is because there is a possibility of becoming.

The positive electrode active material is not particularly limited, and those usable for existing lithium ion secondary batteries can be appropriately used. Preferably, it is a composite oxide of a transition metal and lithium (lithium-transition metal composite oxide) because a battery having excellent capacity and output characteristics can be formed. Specifically, Li · Co-based composite oxide such as LiCoO _2, Li · Ni-based composite oxide such as LiNiO _2, spinel LiMn ₂ O _4, Li · Mn-based composite oxide such as LiMnO _{2, Li 2} Cr Li · Cr composite oxides such as ₂ O ₇ and Li ₂ CrO ₄ , Li · Fe composite oxides such as LiFeO ₂ and Li _x FeO _y, and Li · V composite oxides such as Li _x V _y O _z And those obtained by substituting some of these transition metals with other elements (for example, LiNi _x Co _1-x O ₂ (0 <x <1), etc.), but the present invention is limited to these materials. Is not to be done. These lithium-transition metal composite oxides are excellent in reactivity and cycle durability and are low-cost materials. Therefore, using these materials for the electrodes is advantageous in that a battery having excellent output characteristics can be formed. In the bipolar battery, Li—Mn composite oxide is desirable among the positive electrode active materials. This is because by using the Li—Mn-based composite oxide, the profile can be tilted, and the reliability at the time of abnormality is improved. As a result, there is an advantage that the voltage of each single cell layer and the entire bipolar battery can be easily detected. In addition, transition metal and lithium phosphate compounds and sulfate compounds such as LiFePO ₄ ; transition metal oxides and sulfides such as V ₂ O ₅ , MnO ₂ , TiS ₂ , MoS ₂ , and MoO ₃ ; PbO ₂ , AgO, NiOOH or the like can also be used.

  The particle size of the positive electrode active material is not particularly limited, but it is desirable to select one having an optimal particle size according to the method of applying the positive electrode ink described below. For example, when using a coating method such as a conventional coater or a coating method using a thin film manufacturing technique such as spray coating or screen printing, the particle size of the positive electrode active material is 1 to 100 μm, preferably 1 to 10 μm. It is a range. On the other hand, in a novel ink jet coating method proposed by the present applicant (details will be described later), the particle size of the positive electrode active material is 1 μm or less, preferably 0.05 to 1 μm, more preferably 0.05 to 0. 0.5 μm, particularly preferably in the range of 0.05 to 0.1 μm. When the particle size of the positive electrode active material exceeds 1 μm, the dispersed state of the positive electrode active material particles is not maintained in the positive electrode ink, but it is precipitated, so that stable ink jet coating becomes difficult. In addition, it is difficult to achieve further thinning of the electrode. Further, the lower limit value of the particle size of the positive electrode active material is not particularly limited. However, when the particle size is less than 0.05 μm, it is difficult to produce and preferable discharge characteristics may not be obtained.

  Examples of the conductive material for increasing the electron conductivity include acetylene black, carbon black, graphite, various carbon fibers, and carbon nanotubes. However, it is not necessarily limited to these.

  Further, the particle size of the conductive material is not particularly limited, but it is desirable to select one having an optimum particle size according to the method for applying positive electrode ink described below. For example, when using a coating method such as a conventional coater or a coating method using a thin film manufacturing technique such as spray coating or screen printing, the particle size of the conductive material is in the range of 1 to 100 μm, preferably 1 to 10 μm. It is. On the other hand, in the coating method by the novel ink jet method proposed by the present applicant (details will be described later), it may be 1 μm or less, preferably 0.005 to 0.1 μm, more preferably 0.01 to 0.00. The range is 05 μm. When the particle diameter of the conductive material exceeds 1 μm, the dispersed state of the conductive material particles is not maintained in the positive electrode ink, and the conductive ink particles are precipitated, so that stable ink jet coating becomes difficult. In addition, it is difficult to achieve further thinning of the positive electrode. On the other hand, the lower limit value of the average particle diameter of the conductive material is not particularly limited from the viewpoint of further thinning of the positive electrode.

  The particle diameters of the positive electrode active material and the conductive material are both average particle diameters.

  The particle diameters of the positive electrode active material and the conductive material can be measured, for example, by observing using a scanning electron microscope (SEM), a transmission electron microscope (TEM), or the like.

  The shape of the particles of the positive electrode active material and the conductive material is not limited to a spherical shape, and may be a plate shape, a needle shape, a column shape, a square shape, or the like. The shape of these particles can be appropriately selected in consideration of desired battery characteristics (for example, charge / discharge characteristics and cycle durability). When the particle shape is other than spherical, the particle shape is not uniform. In such a case, the absolute maximum length of the particle is taken as the average particle diameter of the particle. Here, the “absolute maximum length” refers to the maximum distance among the distances between any two points on the particle outline. When measuring the absolute maximum length, it is preferable to use the average value of the absolute maximum length of each particle present in a certain region of the electron micrograph. Alternatively, when each of the active material particles and conductive material particles used in the present invention is selected by sieving, the sieve mesh used for sieving (mesh-through size or mesh path size) may be adopted as the absolute maximum length. Good. The electrode active material particles may be secondary particles obtained by aggregating primary particles.

  As the positive electrode active material and the conductive material particles, those prepared by themselves may be used, and when a product having a desired particle diameter is commercially available, the product may be purchased and used.

  The ratio of “positive electrode active material particle size / conductive material particle size” is preferably “10/1” or more. By setting the ratio of “positive electrode active material particle size / conductive material particle size” to “10/1” or more, the battery characteristics can be made equal or higher without particularly specifying the ratio of the conductive material in the positive electrode ink. it can. For example, when the ratio of “positive electrode active material particle size / conductive material particle size” is “1/1”, the positive electrode active material ratio in the positive electrode ink is increased to 70% (mass ratio) of the positive electrode active material amount. The conductive network formed by the contact between the particles of the conductive material adsorbed on the surface of the active material particles is less likely to be connected (parts are partially cut). As a result, sufficient battery characteristics cannot be expressed. On the other hand, when the ratio of “positive electrode active material particle size / conductive material particle size” is “10/1” or more, the proportion of the conductive material in the positive electrode ink is as small as several percent (mass ratio) of the positive electrode active material amount. Even if it exists, the conductive network formed by the contact between the particles of the conductive material adsorbed on the surface of the positive electrode active material particles will be connected. As a result, sufficient battery characteristics can be exhibited. Such a relationship is particularly useful when a positive electrode ink is applied by an inkjet method using a positive electrode active material and a conductive material having a particle size of 1 μm or less.

  Further, the proportion of the conductive material is appropriately determined according to the purpose of the invention and, further, the particle size of the conductive material and the positive electrode active material. The ratio (mass ratio) of the conductive material may be 10% by mass with respect to the total amount of the positive electrode active material as long as the ratio of “positive electrode active material particle size / conductive material particle size” is satisfied, but is limited to these ranges. Is not to be done.

The electrolytic solution is not particularly limited, and a conventionally known electrolytic solution can be used. What is necessary is just normally used with a lithium ion battery, and what contains lithium salt (electrolyte salt) and an organic solvent (plasticizer) can be used. Specifically, for _{example, LiPF 6, LiBF 4, LiClO} 4, LiAsF 6, LiTaF 6, LiAlCl 4, Li 2 B 10 Cl 10 inorganic acid anion salts such _{as, LiCF 3 SO 3, Li (} CF 3 SO 2 ) ₂ N, including at least one lithium salt (electrolyte salt or supporting salt) selected from organic acid anion salts such as Li (C ₂ F ₅ SO ₂ ) ₂ N, propylene carbonate (PC), Cyclic carbonates such as ethylene carbonate (EC); chain carbonates such as dimethyl carbonate (DMC), methyl ethyl carbonate, and diethyl carbonate (DEC); tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2- Ethers such as dimethoxyethane and 1,2-dibutoxyethane Lactones such as γ-butyrolactone (GBL); nitriles such as acetonitrile; esters such as methyl propionate; amides such as dimethylformamide; one or more selected from at least one selected from methyl acetate and methyl formate And those using an organic solvent (plasticizer) such as an aprotic solvent. However, it is not necessarily limited to these.

  Content of the said electrolyte solution should just be 50 mass% or more with respect to positive electrode preink whole quantity. In this case, since the electrolyte solution is removed after precharging, the electrolyte solution should be more than the active material. When the porosity of the dry state of the active material and the conductive material is approximately 50%, the electrolyte solution for the void is injected. All active materials can be brought into contact with the electrolyte.

(Ii) Pre-charging / degassing / pre-discharging process of positive electrode pre-ink In pre-charging / degassing / pre-discharging process 103, similar to the initial charge / initial discharge in the conventional battery, it was obtained in the process (i) above. The positive electrode pre-ink is fully charged / discharged. In this step, it is desirable to carry out in an atmosphere having a moisture content of 20 ppm or less, or in an atmosphere that does not come into contact with air or the like. This is because, even if the gas generated at the time of the initial charge of the battery is extracted in advance, water and atmospheric gas components are mixed in the ink, but a small amount of the gas generated at the time of the initial charge of the battery. This is because there is a possibility that it becomes a cause.

  FIG. 2 is a schematic cross-sectional view schematically showing an embodiment of an apparatus used for precharging, degassing and predischarging of the electrode preink of the present invention.

  In the apparatus 201, a SUS pre-ink storage container 203 having an open upper surface, which is electrically connected to a charging / discharging power source (not shown), and a SUS product with Li metal (one electrode) attached to the surface. The container lid 205 is provided. The container and the lid may be made of an electrically conductive material. However, since copper may be melted by precharge / discharge, it is desirable to use SUS or the like described above.

  In the precharge step 103a of the positive electrode pre-ink in this step 103, the precharge / discharge device 201 shown in FIG. 2 is used. Specifically, the storage container 203 of the apparatus 201 is filled with the pre-ink 101 ′ including the active material 103 ′ and the conductive material 105 ′ obtained in the step (i), and the separator 207 is covered from above. Is impregnated with an electrolyte. Furthermore, a container lid 205 is installed on the upper surface of the separator 207, and full charge is performed until the positive electrode pre-ink reaches a predetermined voltage (for example, a theoretical charge voltage of 4.2 V of the positive electrode active material) as pre-charge in the above-described reduced pressure atmosphere. . Thereby, the gas generated at the time of the first charge can be generated in advance in this step.

The precharge condition is not particularly limited, but it is desirable to promote the generation of gas at the same level as the initial charge as the same charge condition as the initial charge of the battery. From this point of view, for example, as shown in Example 1 described later, it is desirable to perform constant current and constant voltage charging in a range of about 20 μA / cm ₂ , but the range is not limited thereto.

  Next, as the degassing step 103b, the gas generated with the precharge is removed. Thereby, the gas previously generated in the precharge process can be extracted outside. The degassing step is not particularly limited, but it is preferable to use ultrasonic waves. At this time, it is more desirable to reduce the pressure while vibrating with ultrasonic waves. This is because gas (bubbles) may adhere to the surface of the active material particles or the gaps between the particles due to the precharging step, and even in such cases, the gas (bubbles) can be reliably removed outside the ink. Because. In the prior art, since degassing is performed after coating, it may be impossible to use ultrasonic waves, and it has been difficult to remove the generated gas through the polymer electrolyte layer having low fluidity. In the present invention, the gas adhering to the surface of the active material particles or between the particles can be quickly and surely removed by preferably reducing the pressure while vibrating the suspension pre-ink with ultrasonic waves. The effect can be enhanced. The ultrasonic generator may be incorporated in the storage container 203 of the apparatus 201 shown in FIG. Alternatively, a detachable ultrasonic generator may be prepared separately from the apparatus 201 shown in FIG. 2 and installed in the storage container 203 during the degassing process. .

  By performing the degassing step 103b, as shown in Example 2, the battery performance is improved as compared with Example 3 in which the degassing is not performed. In particular, it can be seen that the output characteristics at a large current can be greatly improved.

  Next, in the pre-discharge process 103c, the pre-discharge of the positive electrode pre-ink is performed after the degassing process 103b.

  Also in the pre-discharge step, the above-described apparatus 201 is used as it is, and the positive electrode side and the negative electrode side are reversed from those at the time of pre-charging, and the positive electrode pre-ink has a predetermined voltage (for example, a theoretical discharge voltage of 2.5 V of the positive electrode active material) as pre-discharge. ) Full discharge until. Thereby, the degassing generated at the time of initial charge can be removed. At the same time, Li ion derived from the active material is reacted with the irreversible capacity sites of the active material by using the Li ion supply source (Li metal attached to the surface of the container lid 205) other than the active material by the precharge / predischarge. It is also possible to prevent the reversible capacity from being reduced due to being trapped at the irreversible capacity site. However, since this effect is more conspicuous on the negative electrode side described later, in this step 103, it can be said that it is not always necessary to attach Li metal or the like as a Li ion supply source to the surface of the container lid 205. It is desirable to attach metal or the like. In particular, when the same apparatus is used for the precharge, degassing, and predischarge processes of the positive electrode and the negative electrode preink, it is also excellent in that the number of parts can be reduced due to the common use of the parts and the mixing of parts can be prevented.

The pre-discharge conditions are not particularly limited, but are preferably the same discharge conditions as the initial discharge of the battery. Specifically, the state is made such that all the stored energy stored in the active material by charging is released (empty state). By doing so, the ink and the electrode can be easily handled. From this point of view, for example, as shown in Example 1 described later, it is desirable to perform constant current discharge in a range of about 20 μA / cm ₂ , but the range is not limited thereto.

  In this process 103, in addition to the order of the precharge process 103a, the degassing process 103b, and the predischarge process 103c described above, for example, the precharge process 103a, the predischarge process 103c, and the degassing process 103b are performed in this order. (See Example 1). Further, the degassing process may be performed twice in the order of the precharging process 103a, the degassing process 103b, the predischarge process 103c, and the degassing process 103b. Any order can be used.

(Iii) Positive electrode pre-ink cleaning / drying step In the positive electrode pre-ink cleaning / drying step 105, after the completion of step 103, the positive electrode pre-ink is taken out from the apparatus 201, washed with an appropriate solvent such as DEC, and vacuum dried. Thus, the volatile component is removed, and the precharged / predischarged active material and conductive material are obtained.

Specifically, as in the examples described later, the positive electrode pre-ink is taken out from the apparatus 201 and submerged in a solvent tank filled with a suitable solvent, for example, DEC, and the electrolyte (for example, LiPF ₆ ) remaining in the positive electrode pre-ink is removed. It may be eluted to the solvent side and then dried under reduced pressure again. However, the present invention is not limited to these.

  In this step, it is desirable to carry out in an atmosphere having a moisture content of 20 ppm or less, or in an atmosphere that does not come into contact with air or the like.

  In this embodiment, the positive electrode pre-ink cleaning / drying step 105 is performed, so that the positive electrode pre-ink cleaning / drying step 105 is not performed, as shown in 4 described later. It can be seen that the battery performance is improved. In particular, it is excellent in that the output characteristics at a large current can be greatly improved.

(Iv) Positive electrode ink preparation step In the positive electrode ink preparation step 107, other components are added to the precharged / predischarged positive electrode active material and conductive material obtained in the above step 105 as necessary to adjust the viscosity. An appropriate amount of a solvent is added and mixed to prepare a positive electrode ink in which the positive electrode active material and the conductive material particles are sufficiently uniformly dispersed.

  The mixing and stirring means may be any means as long as it can sufficiently disperse the electrode active material particles and the conductive material particles in the solvent, and various conventionally known stirring, mixing and stirring devices can be used. There is no particular limitation. Preferably, those capable of performing the mixing and stirring operation quickly and reliably are desirable. As such a suitable mixing and stirring means, for example, a device such as a homogenizer or a stirring deaerator can be used.

  In addition, other components used as necessary include, for example, a binder, a lithium salt for increasing ion conductivity, a polymer electrolyte (polymer raw material, electrolytic solution, etc.), a polymerization initiator, an additive, and the like. However, it is not limited to these. In the present embodiment, as shown in FIG. 1, the pregel solution can be applied after the electrode ink application / drying / pressing / cutting step 109. Therefore, a lithium salt for increasing ion conductivity, a polymer electrolyte (polymer raw material, electrolytic solution, etc.), a polymerization initiator, and the like, which are constituent components of the pregel solution, may not be included as the positive electrode ink. That is, in the present embodiment, it is assumed that the other components used as necessary for the positive electrode ink may include a binder, an additive, and the like. However, it goes without saying that these pregel solution components may be included in other components used as necessary for the positive electrode ink.

  It should be noted that this step is preferably performed in an atmosphere having a moisture content of 20 ppm or less, or in an atmosphere that does not come into contact with air or the like.

  The solvent for adjusting the viscosity is not particularly limited, and examples thereof include N-methyl-2-pyrrolidone (NMP) and acetonitrile. Of course, other solvents may be used.

  As the binder, polyvinylidene fluoride (PVdF), SBR (styrene-butadiene rubber), polyimide, or the like can be used. However, it is not necessarily limited to these.

  Examples of the additive include trifluoropropylene carbonate for enhancing battery performance and life, and various fillers as reinforcing materials. These are included in appropriate amounts as necessary.

  The blending amount of the positive electrode active material, the conductive material, the viscosity adjusting solvent, the binder, the additive, and the like in the positive electrode ink should be determined in consideration of the purpose of use of the battery (output priority, energy priority, etc.).

(V) Application / drying / pressing / cutting process of positive electrode ink In the application / drying / pressing / cutting process 109 of positive electrode ink, first, as an application process 109a, an appropriate material is collected on a current collector (or an appropriate substrate). The positive electrode ink is applied by the method.

  Here, the current collector is not particularly limited, and a conventionally known one can be used. For example, aluminum foil, stainless steel (SUS) foil, nickel-aluminum clad material, copper-aluminum clad material, SUS-aluminum clad material, or a plated material of a combination of these metals can be preferably used. Further, a current collector in which a metal surface is coated with aluminum may be used. Moreover, you may use the electrical power collector which bonded 2 or more metal foil depending on the case. From the viewpoint of corrosion resistance, ease of production, economy, etc., it is preferable to use an aluminum foil as a current collector.

  When the positive electrode and the negative electrode current collector are used separately, as the material of the positive electrode current collector, for example, a conductive metal such as aluminum, an aluminum alloy, SUS, or titanium can be used. Aluminum is particularly preferred. On the other hand, as a material of the negative electrode current collector, for example, a conductive metal such as copper, nickel, silver, or SUS can be used. SUS and nickel are particularly preferable. In addition, the positive electrode current collector and the negative electrode current collector may be electrically connected to each other directly or via a conductive intermediate layer made of a third material.

  Further, the current collector may be formed by forming a film into a desired shape by spray coating, and further by a thin film manufacturing technique such as a screen printing method or an ink jet method. For example, a current collector metal paste containing a metal powder such as aluminum, copper, titanium, nickel, stainless steel (SUS), or an alloy thereof as a main component and containing a binder (resin) and a solvent is formed by heating. It will be. These metal powders may be used singly or as a mixture of two or more, and moreover, by utilizing the characteristics of the manufacturing method, different types of metal powders are laminated in multiple layers. There may be. The binder is not particularly limited. For example, a conventionally known resin binder material such as an epoxy resin can be used, and a conductive polymer material may be used.

  The thickness of the current collector may be as usual and is not particularly limited, but is about 1 to 100 μm. Preferably, from the viewpoint of thinning the electrode, the thickness of the current collector is 100 μm or less, preferably 1 to 50 μm.

  Alternatively, the positive electrode may be formed by applying, drying, pressing, and cutting positive electrode ink on a suitable releasable base material instead of on the current collector. Examples of the appropriate releasable base material include, but are not limited to, release films such as glass and polyethylene. In this case, the positive electrode ink may be applied, dried, pressed, cut, attached to the current collector, and then the substrate on the surface may be peeled off.

  Next, the method for applying the positive electrode ink is not particularly limited. For example, a conventional application method such as an applicator or a coater, or a coating method using a thin film manufacturing technique such as a spray coating, a screen printing method, or an ink jet method. Can be used. In particular, in the coating method by the novel ink jet method proposed by the present applicant, stable ink jet coating is possible even when left for a long time by setting the particle size of the active material and the conductive material to 1 μm or less. Therefore, even a thin film electrode having a thickness of several μm or less can be provided with a thin film electrode having a precisely controlled thickness and density. As a result, the resistance of the lithium polymer battery using the obtained thin film electrode can be made smaller than the resistance of the battery using the electrode obtained by conventional electrode coating using a coater. Therefore, even when charging / discharging at a high current rate as an ultra-high output type lithium polymer battery, it is possible to improve the charging / discharging performance of the battery, for example, necessary energy can be taken out. Hereinafter, an example of a coating method for printing by a method which is one of the preferred coating methods will be described.

  Here, the application method (inkjet method) for printing by an inkjet method is a method of applying ink as droplets from a nozzle of an inkjet printer onto a substrate such as a current collector.

  The ink jet method includes three methods, ie, a piezo element method, a thermal ink jet method, and a continuance method, and any of these methods can be adopted. From the viewpoint of thermal stability of the battery material, the piezo element method is used. Is desirable. The piezo element method is a method using a piezo type, which is generally known as a drop-on-demand method, and discharges a liquid using ceramics (piezo elements) that deform when a voltage is applied. The piezo element method is excellent in thermal stability of a binder, an electrolyte material, and the like included in the positive electrode ink, and can vary the amount of each ink applied. Furthermore, it can discharge liquid with relatively high viscosity reliably, stably and accurately compared to other inkjet heads, and is effective for discharging liquid with a viscosity of about 10-100 Pa · s (10-100 cP). It is excellent in that it can be used.

  In the piezo-type ink jet head, a liquid chamber for storing ink is generally formed, and the liquid chamber has a structure connected to the liquid chamber via an ink introduction portion. A large number of nozzles are arranged in a lower portion of the inkjet head. In addition, a piezoelectric element for ejecting ink in the liquid chamber from the nozzle and a driver for operating the piezoelectric element are disposed in an upper part of the inkjet head. The structure of such an inkjet head is merely an embodiment and is not particularly limited.

  When the ink introduction part is made of plastic, a solvent that can be contained in the ink may dissolve the plastic part. Therefore, the ink introduction part is preferably made of metal having excellent solvent resistance.

  The method for applying the positive electrode ink by an inkjet method is not particularly limited. For example, by providing one inkjet head for positive ink, and controlling the liquid discharge operation of a plurality of micro-diameter nozzles provided on the head independently of each other, droplets are applied to the surface of the current collector (or base material). The method of apply | coating is mentioned. Alternatively, a plurality of ink-jet heads are provided for the positive ink, and a plurality of droplets are simultaneously applied to the surface of the current collector (or base material) by independently controlling the liquid discharge operation of the plurality of micro-diameter nozzles provided on each head. The method of apply | coating simultaneously is mentioned. By such a coating method, the coating speed can be increased, and an electrode can be formed in a short time. Further, in such a coating method, there is no particular limitation for independently controlling the liquid ejection operation. For example, an inkjet printer using the above-described inkjet head may be connected to a commercially available computer or the like, a desired pattern may be created by appropriate software, and control may be performed using an electrical signal from such software. As suitable software, commercially available software such as Power Point (manufactured by Microsoft) and AutoCAD (manufactured by AutoDesk) can be used. However, the software is not limited to commercially available software, and newly developed software may be used.

  The viscosity of the positive electrode ink of the present invention is not particularly limited as long as it is a viscosity suitable for application by inkjet, but is preferably 100 cP or less, more preferably 0.1 to 100 cP. is there. If the viscosity of the positive ink exceeds 100 cP, there is a possibility that it cannot pass through the nozzle. On the other hand, the lower limit of the viscosity of the positive ink is not particularly limited, but if it is less than 0.1 cP, it may be difficult to control the flow rate. In addition, the viscosity of the positive electrode ink as referred to in the present invention means a viscosity at 25 ° C. unless otherwise specified.

  Furthermore, in the present invention, the positive electrode and the negative electrode active material pre-charged / discharged in the manufacturing method of the present embodiment (specifically, the pre-charge / discharge step 103 and the pre-charge / discharge step 123 described below) are used. Using the reversible capacity value after removing the irreversible capacity, it is desirable to design the negative electrode / positive electrode capacity balance to a predetermined value, preferably negative electrode capacity / positive electrode capacity = 1.0 to 1.2. Specifically, the positive and negative ink amounts applied by the positive ink application step 109a and the negative ink application step 129a, and thus the thicknesses of the positive electrode and the negative electrode, are adjusted to be in the above negative electrode capacity / positive electrode capacity range. . The same applies to the second embodiment described later. This is because, for example, when an electrode is produced by a conventional manufacturing method so that both the positive electrode and the negative electrode have the same capacity, an irreversible capacity of about 3% is generated on the positive electrode side at the time of initial charging (reversible capacity is reduced to about 97%). On the other hand, on the negative electrode side, the irreversible capacity is about 20% (reduced to about 80% reversible capacity). Therefore, in the subsequent charge / discharge of the entire battery, the charge / discharge capacity of the battery is limited by the irreversible capacity on the negative electrode side generated at the time of initial charge, and about 17% remains unused on the positive electrode side. It was. In the production method of the present invention, Li ions derived from the active material are trapped at the irreversible capacity site by reacting with the irreversible capacity site of the active material by using a Li ion supply source outside the active material by precharge / predischarge. Thus, the reversible capacity can be prevented from decreasing. As a result, the amount of unused active materials of the positive electrode and the negative electrode can be reduced by adjusting the negative electrode capacity / positive electrode capacity in the above range. In addition, when negative electrode capacity / positive electrode capacity = less than 1.0, metal lithium may be precipitated, and when negative electrode capacity / positive electrode capacity = 1.2 is exceeded, an unused positive electrode active material as in the prior art. As a result, the battery capacity cannot be improved.

  Next, in the drying step 109b after applying the positive ink, the positive ink applied on the current collector (or substrate) is dried under appropriate drying conditions.

  The drying may be performed in a normal atmosphere, preferably in a vacuum atmosphere at 20 to 200 ° C., preferably 80 to 150 ° C., for 1 minute to 8 hours, preferably 3 minutes to 1 hour. However, the present invention is not limited to this, and may be appropriately determined according to the amount of solvent contained in the applied positive electrode ink. In addition, when the positive electrode ink contains a polymer raw material (polymer electrolyte) having a crosslinkable functional group (such as a carbon-carbon double bond) in the molecule and a polymerization initiator, after applying the positive electrode ink The polymer raw material (polymer electrolyte) is polymerized and cured (chemical crosslinking). Such polymerization curing conditions may be appropriately determined according to the type of the polymerization initiator. For example, when a photopolymerization initiator is used, it is 0 to 150 ° C., preferably 20 to 40 ° C. under an inert atmosphere such as argon or nitrogen, preferably under a vacuum atmosphere, preferably 1 minute to 8 hours, preferably It is performed by irradiating with ultraviolet rays for 3 minutes to 1 hour. Moreover, the thermal polymerization initiator may be thermally polymerized and cured at the same time under the above drying conditions.

  Further, as the pressing step 109c after the application and drying of the positive electrode ink, it is desirable to perform a pressing operation on the positive electrode that has been applied and dried by the above method. By performing this pressing operation, the surface of the obtained positive electrode can be further flattened. The apparatus and conditions used for the press operation are not particularly limited, and conventionally known apparatuses and methods can be appropriately used.

  Further, in the industrial production process, as a cutting step 109d after applying, drying, and pressing the positive electrode ink, a positive electrode larger than the final battery size is prepared to improve productivity. You may employ | adopt the cutting process cut to the magnitude | size.

(Vi) Pregel Application Step to Positive Electrode In this embodiment, as the pregel application step 111 to the positive electrode, it is desirable to apply and cure the pregel solution to the positive electrode after applying, drying, pressing and cutting the positive electrode ink. In the present invention, it is desirable that the positive electrode also contains a polymer electrolyte. In the positive electrode produced by applying and curing the pregel solution, the polymer electrolyte can be filled in the gaps between the active material particles and the conductive material particles, the ion conduction at the positive electrode becomes smooth, and the output of the entire battery is improved. It is because it can plan. However, it is not always necessary to apply the pregel solution to the positive electrode. This is because, for example, the electrolyte solution in the polymer gel electrolyte layer can penetrate from the polymer gel electrolyte layer side into voids such as between the active material and conductive material particles in the positive electrode. Or you may mix these pregel solution components in positive electrode ink, and may produce a positive electrode. Thereby, a pregel application process can be omitted.

  Here, the pregel solution contains a lithium salt for increasing ion conductivity, a polymer electrolyte (polymer raw material, electrolytic solution, etc.), a polymerization initiator, and the like.

As the lithium salts to increase the ionic conductivity, for _{example, LiPF 6, LiBF 4, LiClO} 4, LiAsF 6, LiTaF 6, LiAlCl 4, Li 2 B 10 Cl 10 inorganic acid anion salts such as, LiCF ₃ SO ₃ , Organic acids such as Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N (also described as lithium bis (perfluoroethylenesulfonylimide); LiBETI), LiBOB (lithium bisoxide borate) An anion salt or a mixture thereof can be used. However, it is not necessarily limited to these.

  Examples of the polymer electrolyte include an all-solid electrolyte, an all-solid polymer electrolyte, and a polymer gel electrolyte. The difference between the all solid polymer electrolyte and the polymer gel electrolyte (also simply referred to as gel electrolyte) is as follows.

  1) A polymer gel electrolyte is an all-solid polymer electrolyte such as polyethylene oxide (PEO) containing an electrolytic solution used in a normal lithium ion battery.

  2) A polymer gel electrolyte that holds a similar electrolyte in a polymer skeleton having no lithium ion conductivity, such as polyvinylidene fluoride (PVdF).

  3) The ratio of the polymer (host polymer or polymer matrix) constituting the polymer gel electrolyte to the electrolyte is wide. When 100% by mass of the polymer is an all solid polymer electrolyte and 100% by mass of the electrolyte is a liquid electrolyte, the intermediate Are all polymer gel electrolytes.

  4) All solid polymer electrolytes such as polyethylene oxide (PEO) further include those containing a lithium salt (electrolyte salt).

Examples of the all solid electrolyte include ceramic inorganic lithium ion conductors such as Li ₃ N, NASICON type (Li _{1 + x} Al _x Ti _2-x (PO ₄ )), and perovskite type (La _2-3-x Li). _3x TiO ₃ ), silicon type (Li _4-x Ge _1-x P _x S ₄ ), and the like. The all solid electrolyte may further contain a lithium salt (electrolyte salt).

The all solid polymer electrolyte is not particularly limited, and examples thereof include polyalkylene oxide polymers such as polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof. Such a polyalkylene oxide polymer can well dissolve lithium salts such as BETI, LiBF ₄ , LiPF ₆ , LiN (SO ₂ CF ₃ ) ₂ , and LiN (SO ₂ C ₂ F ₅ ) ₂ . In addition, in the positive electrode ink, by adding a polymer raw material (electrolyte polymer) and a polymerization initiator before cross-linking, the positive electrode prepared by inkjet application of the positive ink is promoted by cross-linking polymerization with heat or light, It is desirable to form a cross-linked structure so as to exhibit excellent mechanical strength.

  The polymer gel electrolyte refers to an electrolyte solution held in a polymer matrix. Specifically, a polymer having ion conductivity (so-called solid polymer electrolyte) containing an electrolyte solution usually used in a lithium ion secondary battery, and a polymer not having lithium ion conductivity. A structure in which a similar electrolytic solution is held in the skeleton is also included.

  The polymer material (polymer matrix) of the polymer gel electrolyte is not particularly limited, and conventionally known materials can be used. Preferably, polyethylene oxide (PEO), polypropylene oxide (PPO), polyethylene glycol (PEG), polyacrylonitrile (PAN), polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP), poly (methyl methacrylate) (PMMA) and the like A copolymer having a crosslinkable functional group (such as a carbon-carbon double bond) in the molecule is more preferable. This is because the mechanical strength is improved by crosslinking the polymer raw material using the crosslinkable functional group.

Among these, examples of the polymer having ion conductivity include known polymer electrolytes such as polyethylene oxide (PEO), polypropylene oxide (PPO), and polyalkylene oxide polymers such as copolymers thereof. A polyalkylene oxide polymer such as PEO and PPO can dissolve lithium salts such as LiBF ₄ , LiPF ₆ , LiN (SO ₂ CF ₃ ) ₂ , and LiN (SO ₂ C ₂ F ₅ ) ₂ well. Moreover, excellent mechanical strength is exhibited by forming a crosslinked structure.

  Examples of the polymer having no lithium ion conductivity include monomers that form gelling polymers such as polyvinylidene fluoride (PVDF), polyvinyl chloride (PVC), polyacrylonitrile (PAN), and polymethyl methacrylate (PMMA). Can be used. However, it is not necessarily limited to these. Note that PAN, PMMA, and the like are in a class that has almost no ionic conductivity, and thus can be a polymer having the ionic conductivity. Here, the polymer used for the polymer gel electrolyte is exemplified as a polymer having no lithium ion conductivity.

  The electrolyte solution contained in the polymer gel electrolyte is not particularly limited, and conventionally known electrolyte solutions can be used. In detail, since the thing similar to the electrolyte solution used for the said pre ink can be used, description here is abbreviate | omitted.

  The ratio (mass ratio) between the host polymer and the electrolytic solution in the polymer gel electrolyte may be determined according to the purpose of use and the like, but in the range of 2:98 to 90:10 from the viewpoint of ion conductivity and the like. is there.

  The polymerization initiator is blended in order to act on a crosslinkable group of a polymer raw material such as an ion conductive polymer to advance a crosslinking reaction. Depending on the external factor for acting as a polymerization initiator, it is classified into a photopolymerization initiator, a thermal polymerization initiator and the like. Examples of the polymerization initiator include azobisisobutyronitrile (AIBN) (for thermal polymerization) and benzyldimethyl ketal (BDK) (for photopolymerization). The addition amount of the polymerization initiator is determined according to the number of crosslinkable functional groups contained in the polymer raw material. Usually, it is about 0.01-1 mass% with respect to a polymeric raw material.

  The amount of the pregel solution used should be determined in consideration of the intended use of the battery (emphasis on output, importance on energy, etc.). For example, if the blending amount of the polymer electrolyte in the positive electrode after applying and curing the pregel solution is too small, the ion conduction resistance and the ion diffusion resistance in the positive electrode are increased, and the battery performance is deteriorated. On the other hand, if the amount of the polymer electrolyte in the positive electrode is too large, the energy density of the battery is lowered. Therefore, in consideration of these factors, the amount of the pregel solution that matches the purpose may be determined.

  The method for applying the pregel solution is not particularly limited, and a small amount can be supplied by using an applicator or a coater.

  The pregel solution contains a polymer raw material (polymer electrolyte material having a crosslinkable functional group (such as a carbon-carbon double bond) in the molecule) and a polymerization initiator. Therefore, after the pregel solution is applied, the polymer raw material is polymerized and cured (chemical crosslinking). Such polymerization curing conditions may be appropriately determined according to the type of the polymerization initiator. For example, when a photopolymerization initiator is used, it is 0 to 150 ° C., preferably 20 to 40 ° C. under an inert atmosphere such as argon or nitrogen, preferably under a vacuum atmosphere, preferably 1 minute to 8 hours, preferably It is performed by irradiating with ultraviolet rays for 3 minutes to 1 hour. Further, when a thermal polymerization initiator is used, it is preferably carried out in a normal atmosphere, preferably a vacuum atmosphere, at a temperature at which the electrolytic solution does not volatilize, 20 to 200 ° C., preferably 80 to 150 ° C. What is necessary is just to heat-polymerize and harden for minutes to 8 hours, preferably 3 minutes to 1 hour.

  The thickness of the positive electrode obtained by the pregel application step 111 in this step is not particularly limited, and should be determined in consideration of the intended use of the battery (emphasis on output, energy, etc.). In the present invention, since the positive electrode is applied and formed by an ink jet method, it is suitable for a thin film electrode, but even a thick electrode can be formed without any problem. Accordingly, the thickness of the positive electrode may be about 10 to 500 μm, similar to the case of the conventional coater coating method. Furthermore, a thin film electrode having a thickness of several μm or less, which is difficult to be formed by conventional coater coating, can be obtained. From the viewpoint of thinning the positive electrode, the thickness of the positive electrode is desirably 15 μm or less, preferably 1 to 15 μm, more preferably 5 to 15 μm. This is because the positive electrode can be made thinner, and the battery can be made thinner, smaller, and lighter. When the thickness of the positive electrode exceeds 15 μm, it may be difficult to reduce the thickness of the positive electrode. Note that the lower limit of the thickness of the positive electrode is not particularly limited. The thickness of the positive electrode here refers to the thickness of the positive electrode layer formed on one side of the current collector.

(2) Negative electrode formation step (i) Negative electrode pre-ink preparation step In the negative electrode pre-ink preparation step 121, among the components constituting the negative electrode, when the negative electrode active material and further the negative electrode active material do not have electronic conductivity, the electron conductivity A conductive material for increasing the viscosity is blended at a predetermined blending ratio, and a necessary amount of electrolytic solution suitable for precharge / predischarge is added and suspended therein to prepare a negative electrode preink. At this stage, it is better not to add other components constituting the negative electrode. In particular, when a viscosity adjusting solvent such as NMP is included, if the solvent is present in a state where a potential is applied, it reacts to generate gas, which hinders precharge / predischarge of the electrode active material. This is because there is a possibility of becoming.

The negative electrode active material is not particularly limited, and a material usable for an existing lithium ion secondary battery can be appropriately used. Specifically, carbon, a metal compound, a metal oxide, a Li metal compound, a lithium-metal composite oxide, boron-added carbon, or the like can be used. These may be used alone or in combination of two or more. Carbon or lithium-transition metal composite oxide is preferable. This is because a battery excellent in capacity and output characteristics (for example, the battery voltage can be increased) can be configured by using these. As the lithium-transition metal composite oxide, for example, a lithium-titanium composite oxide represented by Li _x Ti _y O _z such as Li ₄ Ti ₅ O ₁₂ can be used. In addition, as the carbon, for example, various natural graphites and artificial graphites, for example, graphites such as fibrous graphite, flake graphite, and spherical graphite, graphite carbon, hard carbon, soft carbon, acetylene black, carbon black, and the like are used. Can do. Examples of the metal oxide include, in addition to titanium oxide, SnO, SnO ₂ , GeO, GeO ₂ , In ₂ O, In ₂ O ₃ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₃ O ₄ , Transition metal oxides such as Ag ₂ O, AgO, Ag ₂ O ₃ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ , SiO, ZnO, CoO, NiO, and FeO can be used. Examples of the metal compound include LiAl, LiZn, Li ₃ Bi, Li ₃ Cd, Li ₃ Sd, Li ₄ Si, Li _4.4 Pb, Li _4.4 Sn, and Li _0.17 C (LiC ₆ ). It is done. Examples of the Li metal compound include Li ₃ FeN ₂ , Li _2.6 Co _0.4 N, Li _2.6 Cu _0.4 N, and the like. Examples of the boron-added carbon include boron-added carbon and boron-added graphite. However, in this invention, it should not be restrict | limited to these but a conventionally well-known thing can be utilized suitably. The boron content in the boron-added carbon is preferably in the range of 0.1 to 10% by mass, but should not be limited to this. In the case of a bipolar battery, the negative electrode active material is preferably selected from a crystalline carbon material and an amorphous carbon material. By using these, the profile can be tilted, and the voltage of each single cell layer and the entire bipolar battery can be easily detected. The crystalline carbon material here refers to a graphite-based carbon material, and includes the above-described graphite carbon and the like. The non-crystalline carbon material refers to a hard carbon-based carbon material, and includes the hard carbon and the like.

  The particle size of the negative electrode active material is not particularly limited, but it is desirable to select one having an optimum particle size according to the negative electrode ink application method described below. For example, when using a coating method such as a conventional coater or a coating method using a thin film manufacturing technique such as spray coating or screen printing, the particle size of the negative electrode active material is 1 to 100 μm, preferably 1 to 10 μm. It is a range. On the other hand, in a novel inkjet method coating method proposed by the present applicant (details will be described later), the particle size of the negative electrode active material is 1 μm or less, preferably 0.05 to 1 μm, more preferably 0.05 to 0. The range is 1 μm. When the particle size of the negative electrode active material exceeds 1 μm, the dispersed state of the positive electrode active material particles is not maintained in the positive electrode ink, but it is precipitated, so that stable ink jet coating becomes difficult. In addition, it is difficult to achieve further thinning of the electrode. Further, the lower limit value of the particle size of the negative electrode active material is not particularly limited. However, when it is less than 0.05 μm, it is difficult to produce and preferable discharge characteristics may not be obtained.

  As the negative electrode active material particles, those prepared by themselves may be used, and when a product having a desired particle diameter is commercially available, the product may be purchased and used.

  The shape of the particles of the negative electrode active material is the same as the shape of the particles of the positive electrode active material described in the positive electrode pre-ink preparation step 101, and thus description thereof is omitted here.

  Since the type, particle size, shape, and ratio of the conductive material are the same as the type, particle size, shape, and ratio of the conductive material described in the positive electrode pre-ink preparation step 101, description thereof is omitted here.

  Further, the ratio of “negative electrode active material particle size / conductive material particle size” is also the same as the ratio of “positive electrode active material particle size / conductive material particle size” in the positive electrode pre-ink preparation step 101, and therefore the description here. Is omitted.

  The particle size of the negative electrode active material also refers to the average particle size. In addition, the particle size of the negative electrode active material can also be measured by observing using a scanning electron microscope (SEM), a transmission electron microscope (TEM), or the like.

  About the kind and content of the said electrolyte solution, since it is the same as that of the kind and content of the electrolyte solution demonstrated in the said positive electrode pre-ink preparation process 101, description here is abbreviate | omitted.

(Ii) Pre-charging / degassing / pre-discharge process of negative electrode pre-ink In pre-charging / degassing / pre-discharge process 123, similar to the initial charge / initial discharge in the conventional battery, the above-mentioned (i) was obtained. The negative pre-ink is fully charged / discharged. In this step, it is desirable to carry out in an atmosphere having a moisture content of 20 ppm or less, or in an atmosphere that does not come into contact with air or the like. This point is due to the same reason as described in the precharge / degas / predischarge process of the positive electrode preink.

  The pre-charging step 123a of the negative electrode pre-ink in this step 203 can also be performed using the pre-charging / discharging device 201 shown in FIG. Specifically, the storage container 203 of the apparatus 201 is filled with the reink 101 ′, and the separator 207 is placed thereon, and the separator is impregnated with the electrolytic solution. Furthermore, a container lid 205 is installed on the upper surface of the separator 207, and full charge is performed until the negative electrode pre-ink reaches a predetermined voltage (for example, a theoretical charge voltage of 0 V for the negative electrode active material) as pre-charge in the above-described reduced pressure atmosphere. Thereby, the gas generated at the time of the first charge can be generated in advance in this step.

  The precharge conditions can be performed in the same manner as the precharge conditions described in the precharge, degassing, and predischarge processes of the positive electrode pre-ink, and thus the description thereof is omitted here.

  Next, as the degassing step 123b, the gas generated with the precharge is removed. The degassing step 123b can be performed in the same manner as the degassing step 103b described in the precharge, degassing, and predischarge steps of the positive electrode pre-ink, and the description thereof is omitted here. To do.

  Next, in the pre-discharge process 123c, the pre-discharge of the negative electrode pre-ink is performed after the degassing process 123b.

  Also in the pre-discharge step, the above-described apparatus 201 is used as it is, and the positive electrode side and the negative electrode side are reversed from those at the time of pre-charging, so that the positive electrode pre-ink has a predetermined voltage (for example, a theoretical discharge voltage of 2.5 V of the negative electrode active material) as pre-discharge. ) Full discharge until.

  The pre-discharge step 123c can be performed in the same manner as the pre-discharge step 103c described in the pre-charge / degas / pre-discharge step of the positive electrode pre-ink, and can be performed in the same manner. To do. The same applies to pre-discharge conditions.

  In addition, in this process 123, in addition to the order of the precharge process 123a, the degassing process 123b, and the predischarge process 123c, for example, the precharge process 123a, the predischarge process 123c, and the degassing process 123b may be performed in this order. Good (see Example 1). Further, the degassing step may be performed twice in the order of the precharging step 123a, the degassing step 123b, the predischarge step 123c, and the degassing step 123b. Any order can be used.

(Iii) Negative electrode pre-ink cleaning / drying step In the negative electrode pre-ink cleaning / drying step 125, after the step 123 is completed, the negative electrode pre-ink is taken out from the device 201, washed with an appropriate solvent such as DEC, and vacuum dried. As a result, the volatile components are removed to obtain a precharged / predischarged active material, and further a conductive material.

Specifically, as in the examples described later, the negative electrode pre-ink is taken out from the apparatus 201 and submerged in a solvent tank filled with a suitable solvent, for example, DEC, and an electrolyte (for example, LiPF ₆ ) remaining in the negative electrode pre-ink is removed. It may be eluted to the solvent side and then dried under reduced pressure again.
Also in this step, it is desirable to carry out in an atmosphere having a moisture content of 20 ppm or less, or in an atmosphere that does not come into contact with air or the like.

(Iv) Negative electrode ink preparation step In the negative electrode ink preparation step 127, the precharged / predischarged negative electrode active material obtained in the above step 125, and other components are added to the conductive material as necessary to adjust the viscosity. An appropriate amount of the above solvent is added and mixed to prepare a negative electrode ink in which the negative electrode active material and further the conductive material particles are sufficiently uniformly dispersed. In the negative electrode ink, the conductive material is not an essential component, and may be used when the negative electrode active material does not have electronic conductivity.

  Regarding the mixing and stirring means, since the same mixing and stirring means as described in the positive electrode ink preparation step 107 can be used, description thereof is omitted here.

  The viscosity adjusting solvent and other components used as necessary are the same as the viscosity adjusting solvent described in the positive electrode ink preparation step 107 and other components used as necessary. Therefore, the description here is omitted.

  The amount of the negative electrode active material, conductive material, viscosity adjusting solvent, binder, additive, and the like in the negative electrode ink should be determined in consideration of the intended use of the battery (output priority, energy priority, etc.).

(V) Application / drying / pressing / cutting process of negative electrode ink In the application / drying / pressing / cutting process 129 of negative electrode ink, first, as a coating process 129a, an appropriate material is collected on a current collector (or an appropriate substrate). The negative electrode ink is applied by the method.

  Type, thickness, and description of the current collector, negative electrode ink application method (including ink-jet application method), negative ink viscosity, droplet size, between adjacent droplet centers Regarding the distance, the type, thickness, and description of the current collector described in the positive ink application process 109a, the positive electrode ink application method (including the ink jet application method), the positive ink viscosity, and the liquid Since it is the same as the particle size of a droplet and the distance between the centers of adjacent droplets, description here is omitted.

  Next, in the drying step 129b after application of the negative electrode ink, the negative electrode ink applied on the current collector (or substrate) is dried under appropriate drying conditions.

  The drying conditions are the same as the drying means described in the positive electrode ink drying step 109b, and thus the description thereof is omitted here.

  In addition, as the pressing step 109c after applying and drying the negative electrode ink, it is desirable to perform a pressing operation on the negative electrode that has been applied and dried by the above method. By performing this pressing operation, the surface of the obtained negative electrode can be further flattened. The apparatus and conditions used for the press operation are not particularly limited, and conventionally known apparatuses and methods can be appropriately used.

  Further, in an industrial production process, as a cutting process 129d after application, drying, and pressing of the negative electrode ink, a negative electrode larger than the final battery size is prepared to improve productivity. You may employ | adopt the cutting process cut to the magnitude | size.

(Vi) Pregel Application Step to Negative Electrode In this embodiment, as the pregel application step 131 to the negative electrode, it is desirable to apply and cure the pregel solution to the positive electrode after applying, drying, pressing and cutting the negative electrode ink.

  Regarding the pregel application step 131, the same effects as the pregel application step 111 on the positive electrode are achieved, and the components of the same pregel solution (lithium salt, polymer electrolyte (polymer raw material, electrolyte, etc.), polymerization initiator), Since it can carry out using the usage-amount, the application | coating method, and polymerization hardening conditions, description here is abbreviate | omitted.

  The thickness of the negative electrode produced by the pregel application step 131 on the negative electrode is the same as the thickness of the positive electrode produced by the pregel application step 111 on the positive electrode, and thus the description thereof is omitted here.

(3) Formation process of polymer electrolyte layer (i) Preparation process of pregel solution In the preparation process 141 of the pregel solution, a pregel solution made of a lithium salt, a polymer electrolyte (polymer raw material, electrolyte, etc.), and a polymerization initiator is prepared. .

  About the said pregel solution, since it can produce using the component of the pregel solution similar to having demonstrated at the pregel application | coating process 111 of the said positive electrode, the description is abbreviate | omitted here.

  About the composition component of the said pregel solution, its compounding quantity, etc., it should be suitably determined according to the intended purpose. For example, the ratio of the electrolytic solution in the pregel solution is not particularly limited, but is preferably about several mass% to 98 mass% from the viewpoint of ion conductivity and the like.

(Ii) Application process of pregel solution to separator In the pregel application process 143 to the separator, first, a desired separator is prepared.

  The separator is not particularly limited, and a conventionally known separator can be used. For example, (1) a porous separator made of a polymer that absorbs and retains an electrolyte (for example, polyolefin microporous) Or a non-woven separator used to hold the electrolyte.

  Among these, in the porous separator of the above (1), the polyolefin microporous separator having the property of being chemically stable with respect to the organic solvent suppresses the reactivity with the electrolyte (electrolyte). It has the outstanding effect that it can do.

  Examples of the material of the polymer that absorbs and holds the electrolyte of (1) include polyethylene (PE), polypropylene (PP), a laminate having a three-layer structure of PP / PE / PP, and polyimide.

  The thickness of the separator in (1) above cannot be unambiguously defined because it varies depending on the usage, but in applications such as secondary batteries for driving motors such as electric vehicles (EV) and hybrid electric vehicles (HEV). Is preferably 4 to 60 μm in a single layer or multiple layers. The mechanical strength in the thickness direction is desirable because the thickness of the separator is within such a range, and it is desirable to narrow the gap between the electrodes for high output and prevention of short-circuiting caused by fine particles entering the separator. And there is an effect of ensuring high output performance. In addition, when a plurality of batteries are connected, the electrode area increases, so that it is desirable to use a thick separator in the above range in order to increase the reliability of the battery.

  It is desirable that the fine pore diameter of the separator (1) is 1 μm or less (usually a pore diameter of about several tens of nm). Due to the fact that the average diameter of the micropores in the separator is within the above range, the “shutdown phenomenon” that the separator melts due to heat and the micropores close quickly occurs, resulting in higher reliability during abnormalities, resulting in heat resistance. Has the effect of improving. In other words, when the battery temperature rises due to overcharging (in an abnormal state), the “shutdown phenomenon” that the separator melts and closes the micropores occurs quickly, so that the positive electrode (+) of the battery (electrode) Li ions cannot pass through to the negative electrode (−) side, and no further charge is possible. As a result, overcharging cannot be performed and overcharging is eliminated. As a result, the heat resistance (safety) of the battery is improved, and it is possible to prevent gas from being released and the heat fusion part (seal part) of the battery exterior material from being opened. Here, the average diameter of the micropores of the separator is calculated as an average diameter obtained by observing the separator with a scanning electron microscope or the like and statistically processing the photograph with an image analyzer or the like.

  The porosity of the separator (1) is preferably 20 to 50%. The separator's porosity is within the above range, preventing output from being reduced due to the resistance of the electrolyte (electrolyte), and preventing the short circuit caused by fine particles penetrating the separator's pores (micropores). It has the effect of securing both sexes. Here, the porosity of the separator is a value obtained as a volume ratio from the density of the raw material resin and the density of the separator of the final product.

  The amount of impregnation of the polymer electrolyte into the separator of (1) may be impregnated up to the holding capacity range of the separator, but it may be impregnated beyond the holding capacity range. This can be impregnated as long as it can be retained in the electrolyte layer because a seal portion is provided in the electrolyte and the electrolyte solution can be prevented from exuding from the electrolyte layer.

  The nonwoven fabric separator used to hold the electrolyte of (2) is not particularly limited, and can be produced by entwining fibers into a sheet. Moreover, the spun bond etc. which are obtained by fusing fibers by heating can also be used. In other words, it may be in the form of a sheet formed by arranging fibers in a web (thin cotton) shape or mat shape by an appropriate method, and joining them using an appropriate adhesive or the fusing force of the fibers themselves. The adhesive is not particularly limited as long as it has sufficient heat resistance at the temperature during manufacture and use, and is stable without any reactivity or solubility with respect to the gel electrolyte. In addition, conventionally known ones can be used. In addition, the fiber used is not particularly limited, and for example, conventionally known fibers such as cotton, rayon, acetate, nylon, polyester, polypropylene, polyethylene such as polyethylene, polyimide, and aramid can be used. Depending on (such as mechanical strength required for the electrolyte layer), they are used alone or in combination. Further, the bulk density of the nonwoven fabric is not particularly limited as long as sufficient battery characteristics can be obtained by the impregnated polymer gel electrolyte. That is, if the bulk density of the nonwoven fabric is too large, the proportion of the non-electrolyte material in the electrolyte layer becomes too large, which may impair the ionic conductivity in the electrolyte layer.

  The porosity of the nonwoven fabric separator (2) is preferably 50 to 90%. If the porosity is less than 50%, the electrolyte retention deteriorates, and if it exceeds 90%, the strength is insufficient. Furthermore, the thickness of the nonwoven fabric separator may be the same as that of the electrolyte layer, preferably 1 to 200 μm, and particularly preferably 1 to 50 μm. When the thickness is less than 1 μm, the electrolyte retention deteriorates, and when it exceeds 200 μm, the resistance increases.

  The method of applying the pregel solution to the separator is particularly limited, for example, the pregel solution may be impregnated and applied, or the separator may be spray coated with the pregel solution. Instead, a conventionally known method can be used.

  In the present invention, the amount of the electrolytic solution in the pregel solution contained in the separator may be substantially uniform inside the separator, or may be decreased in an inclined manner from the central portion toward the outer peripheral portion. Also good. The former is preferable because reactivity can be obtained in a wider range, and the latter is preferable in that the sealing performance of the separator outer peripheral portion with respect to the electrolyte can be improved. In the case of decreasing the inclination from the center to the outer periphery of the separator, it is desirable to use PEO, PPO and copolymers thereof having lithium ion conductivity as the host polymer in the pregel solution. .

  The thickness of the electrolyte layer formed by applying the pregel solution to the separator is not particularly limited, and is usually 1 to 200 μm, particularly preferably 1 to 50 μm. When the thickness is less than 1 μm, the electrolyte retention deteriorates, and when it exceeds 200 μm, the resistance increases. However, in order to obtain a compact lithium-ion secondary battery with a stacked type, it is preferable to make it as thin as possible within a range that can ensure the function as an electrolyte. In particular, when using a thin film electrode of several μm or less, which is not conventionally used, it is desirable to employ a thin electrolyte layer corresponding to this.

  Next, the pregel solution is applied to the separator by an appropriate application method, and then dried and cured (photopolymerization) or heat-dried (thermal polymerization) in an inert atmosphere to produce a polymer electrolyte layer.

  For the drying and curing or heat drying, a vacuum dryer (vacuum oven), an ultraviolet irradiation device or the like can be used. The conditions of dry curing or heat drying are determined according to the polymerization form of the pregel solution and cannot be uniquely defined, but in heat drying (thermal polymerization), it is usually 30 to 110 ° C. for 0.5 to 12 hours. . In the case of dry curing (photopolymerization) using a photopolymerization initiator, the separator is impregnated by irradiating with ultraviolet rays using an ultraviolet irradiation device that can be poured into a light-transmitting gap and capable of drying and photopolymerization. The polymer raw material (crosslinkable polymer) in the pregel solution may be photopolymerized to advance the crosslinking reaction to form a film. However, it is needless to say that the method is not limited to this. Depending on the type of polymerization initiator, radiation polymerization, electron beam polymerization, thermal polymerization, etc. are used properly.

  The width of the polymer electrolyte layer is often slightly smaller than the current collector size of the electrode.

  The order of (1) formation of the positive electrode, (2) formation of the negative electrode, and (3) formation of the polymer electrolyte layer is not particularly limited, and may be prepared before they are laminated.

(4) Battery manufacturing process (i) In the assembly process 151 of the positive electrode, the negative electrode, and the polymer electrolyte layer, the positive electrode and the negative electrode are sufficiently heated and dried under high vacuum, and then the positive electrode or bipolar electrode, polymer An electrode laminate (battery element portion) having a structure in which a plurality of electrolyte layers, negative electrodes or bipolar electrodes are laminated in this order is formed.

  In the present invention, depending on how (1) the positive electrode is formed and (2) the negative electrode is formed, an electrode (referred to as a general electrode) used in a bipolar electrode used in a bipolar battery and a non-bipolar battery (referred to as a general battery). This is because any of the above can be produced.

  Here, there are two types of general electrodes: a positive electrode created using positive electrode ink on both surfaces of the positive electrode current collector and a negative electrode created using negative electrode ink on both surfaces of the negative electrode current collector. . However, in the general electrodes located at both ends of the battery, a positive electrode or a negative electrode prepared using a positive electrode ink or a negative electrode ink may be used only on the surface of one side of the positive electrode or the negative electrode current collector.

  On the other hand, the bipolar electrode has both a positive electrode made using a positive electrode ink on one surface of a current collector and a negative electrode made using a negative ink on the other surface of the current collector. It is a thing. However, in the bipolar electrodes located at both ends of the battery, electrodes made using positive electrode ink or negative electrode ink may be used only on one surface of the current collector.

  The number of stacked electrode laminates is determined in consideration of battery characteristics required for the battery. In a bipolar battery, an electrode (a positive electrode for current extraction) in which only a positive electrode layer is formed on a current collector is disposed on the outermost layer on the positive electrode side. In the outermost layer on the negative electrode side, an electrode (negative electrode for current extraction) in which only the negative electrode layer is formed on the current collector is disposed. The step of obtaining the lithium polymer battery by laminating the electrode and the polymer electrolyte layer is preferably performed in an inert atmosphere from the viewpoint of preventing moisture and the like from being mixed into the battery. For example, a lithium polymer battery may be manufactured under an argon atmosphere or a nitrogen atmosphere.

  In this step, the periphery of the electrode of the electrode laminate may be immersed in epoxy resin (precursor solution) or the like with a predetermined width, or resin may be injected or impregnated. In any case, the voltage detection tab, the electrode tab, the electrode lead, or the current collector portion to which these need to be connected are masked in advance using a releasable masking material or the like. Thereafter, the epoxy resin is cured to form an insulating seal image, and then the masking material is peeled off.

  In this step, for example, in the case of a bipolar battery, finally, a positive high voltage tab and a negative high voltage tab are respectively installed on the current collectors for current extraction of both outermost layers of the electrode stack, Then, a positive electrode lead and a negative electrode lead are further joined (electrically connected) to the negative electrode high voltage tab and taken out of the battery. In a general battery, a positive electrode lead and a negative electrode lead are joined (electrically connected) to each electrode current collector, and these are collectively joined to a positive electrode and a negative electrode terminal tab (electrically connected). Remove the battery from the outside.

  There are no particular limitations on the method of joining the positive and negative high-voltage tabs, the positive and negative lead, the positive and negative terminal tabs, but ultrasonic welding with a low joining temperature can be suitably used. However, the present invention is not limited to this, and a conventionally known joining method can be appropriately used.

  In order to prevent external impact and environmental degradation, the entire electrode laminate is sealed with a battery exterior material or battery case to complete a lithium polymer battery. The material of the battery exterior material (battery case) is preferably a metal (aluminum, stainless steel, nickel, copper, etc.) whose inner surface is covered with an insulator such as a polypropylene film.

(Ii) Recharging Step In the recharging step 153, it is desirable to recharge the lithium polymer battery under the same conditions as the initial charging of the conventional battery. Thereby, the subsequent ace / inspection process can be performed.

(Iii) Aging / Inspection Step In the aging / inspection step 155, it is desirable to perform aging / inspection of the lithium polymer battery in the recharging step 153.

  FIG. 3 is a process flowchart of a representative embodiment (also referred to as a second embodiment) of a method for producing a lithium polymer battery of the present invention.

As shown in FIG. 3, in the manufacturing method according to the second embodiment of the lithium polymer battery of the present invention;
(1) As a positive electrode forming step, (i) a positive electrode preink preparation step 201, (ii) a precharge / degassing / predischarge step 203 of the positive electrode preink, (iii) a coating / drying step 205 of the positive electrode preink, (Iv) a binder solution applying / drying step 207 to the positive electrode, (v) a positive electrode pressing / cutting step 209, and (vi) a pregel solution applying step 211 to the positive electrode.

  Similarly, (2) the negative electrode forming step, (i) the negative electrode pre-ink preparation step 221; (ii) the negative electrode pre-ink precharge / degassing / pre-discharge step 223; and (iii) the negative electrode pre-ink application / drying step. 225, (iv) a binder solution application / drying step 207 to the negative electrode, (v) a negative electrode pressing / cutting step 209, and (vi) a pregel solution application step 211 to the negative electrode. .

  Moreover, (3) As a formation process of a polymer electrolyte layer, it has (i) preparation process 241 of a pregel solution, and (ii) pregel application | coating process 243 to a separator.

  Next, (4) the battery manufacturing process includes (i) a process 251 for assembling a positive electrode, a negative electrode, and a polymer electrolyte layer, (ii) a recharging process 253, and (iii) an aging / inspection process 255. is there.

  That is, the second embodiment is different from the first embodiment in that the pre-ink after the discharge in step 103 is applied and dried on the current collector without performing the cleaning / drying step 105, and then the binder. The solution is applied and dried. Therefore, the volatile component of the electrolytic solution in the pre-ink evaporates in the drying step 205b after the application in step 205. Therefore, it is necessary to adjust the volatile component in the pre-gel solution prepared in step 211. Conventionally, in order to produce an electrode slurry, it is necessary to uniformly disperse the active material and the binder, and the preparation time has taken a considerable time. However, in the second embodiment, since the active material and the binder can be applied separately, such a problem can be solved.

  In the second embodiment, the active material pre-charged / pre-discharged in step 203 and the binder solution prepared in step 207 are separately applied (step 205 and step 207). Thereby, it is excellent at the point which can suppress the deterioration of the battery characteristic by decomposition | disassembly of NMP, without the active material once charged and NMP in a binder solution contacting for a long time.

  In the first and second embodiments, the most preferable examples in which both the positive electrode and the negative electrode are precharged / predischarged are shown. However, the present invention is not limited to these, and only one of the electrodes is used. But it ’s okay. In either case, it is desirable to precharge / predischarge the negative electrode.

  Hereinafter, each process according to the second embodiment will be described in detail.

(1) Positive electrode formation step (i) Positive electrode pre-ink preparation step The positive electrode pre-ink preparation step 201 according to the second embodiment is the same as the positive electrode pre-ink preparation step 101 according to the first embodiment, and thus description thereof is omitted here. To do.

(Ii) Precharging / Degassing / Pre-Discharging Step of Positive Electrode Preink Precharging / degassing / pre-discharging step 203 of the positive electrode preink according to the second embodiment includes precharging / degassing of the positive electrode preink according to the first embodiment. -Since it is the same as that of the pre-discharge process 103, description here is abbreviate | omitted.

(Iii) Positive Preink Ink Application / Drying Step In the positive electrode preink application / drying step 205 according to the second embodiment, (v) the positive electrode ink application / drying / pressing / cutting step 109 according to the first embodiment has been described. In the same manner as described above, the positive electrode pre-ink is applied to the current collector and dried. In this step, it is desirable to carry out in an atmosphere having a moisture content of 20 ppm or less, or in an atmosphere that does not come into contact with air or the like. This is because, even if the gas generated at the time of the initial charge of the battery is extracted in advance, water and atmospheric gas components are mixed in the ink, but a small amount of the gas generated at the time of the initial charge of the battery. This is because there is a possibility that it becomes a cause.

  First, as a coating process 205a, a positive electrode pre-ink is coated on a current collector (or a suitable base material) by a suitable method.

  Type of collector, thickness, description of base material, positive electrode pre-ink application method (including ink-jet application method), positive electrode pre-ink viscosity, droplet size, between adjacent droplet centers For the distance, the type, thickness, and description of the current collector described in the positive ink application step 109a of the first embodiment, the description of the base material, and the positive ink application method (including the ink jet method), Since it can be performed in the same manner as the viscosity of the positive electrode ink, the particle size of the droplets, and the distance between the centers of adjacent droplets, description thereof is omitted here.

  Next, in the drying step 205b after the application of the positive electrode pre-ink, the positive electrode pre-ink applied on the current collector (or substrate) is dried under appropriate drying conditions to form the positive electrode.

  The drying conditions can be the same as the drying conditions described in the positive ink drying step 109b of the first embodiment, and thus the description thereof is omitted here.

(Iv) Binder Solution Application / Drying Step to Positive Electrode In the binder solution application / drying step 207 to the positive electrode, first, a binder solution is prepared. The binder solution may contain a binder, a solvent for adjusting viscosity, an additive, and the like.

  The binder, the viscosity adjusting solvent, and the additive may be the same as the binder, the viscosity adjusting solvent, and the additive described in the positive electrode ink preparation step 107 of the first embodiment. The description in is omitted.

  The blending amount of the binder, viscosity adjusting solvent, additive, etc. in the binder solution should be determined in consideration of the intended use of the battery (emphasis on output, emphasis on energy, etc.).

  Next, in the step of applying a binder solution 207a to the positive electrode, the prepared binder solution is applied to the positive electrode prepared in (iii) by an appropriate method.

  The binder solution coating method (including a method of coating by an ink jet method), the binder solution viscosity, the droplet particle size, and the distance between the centers of adjacent droplets are as follows. Since it can be performed in the same manner as the method for applying the positive electrode ink, the viscosity of the positive electrode pre-ink, the particle size of the liquid droplets, and the distance between the centers of adjacent liquid droplets described in Step 109a, description thereof is omitted here.

  Next, in a drying step 207b after applying the binder solution, the binder solution applied on the positive electrode is dried under appropriate drying conditions.

  The drying conditions can be the same as the drying conditions described in the positive ink drying step 109b of the first embodiment, and thus the description thereof is omitted here.

  This step 207 is also preferably performed in an atmosphere having a moisture content of 20 ppm or less, or in an atmosphere that does not come into contact with air or the like.

(V) Positive electrode pressing / cutting step In the positive electrode pressing / cutting step 209, first, as a pressing step 209a after applying and drying the binder solution, the positive electrode applied and dried in the above step 207 is pressed. desirable. By performing this pressing operation, the surface of the obtained positive electrode can be further flattened. The apparatus and conditions used for the press operation are not particularly limited, and conventionally known apparatuses and methods can be appropriately used.

  Furthermore, in an industrial production process, as a cutting step 209b after pressing, in order to improve productivity, a positive electrode larger than the final battery size is produced, and this is cut into a predetermined size. A process may be adopted.

(Vi) Pregel Application Step on the Positive Electrode In the pregel application step 211 on the positive electrode, it is desirable to apply and cure the pregel solution to the positive electrode after the positive electrode pressing / cutting step 209.

  The pregel application step 211 on the positive electrode according to the second embodiment is the same as the pregel application step 111 on the positive electrode according to the first embodiment, and a description thereof will be omitted here.

(2) Negative electrode forming step (i) Negative electrode pre-ink preparation step The negative electrode pre-ink preparation step 221 according to the second embodiment is the same as the negative electrode pre-ink preparation step 121 according to the first embodiment, and a description thereof is omitted here. To do.

(Ii) Precharging / degassing / pre-discharge step of negative electrode pre-ink The pre-charging / degassing / pre-discharge step 223 of the negative electrode pre-ink according to the second embodiment is performed in the pre-charging / degassing of the negative electrode pre-ink according to the first embodiment. -Since it is the same as that of the pre-discharge process 123, description here is abbreviate | omitted.

(Iii) Application / Drying Step of Negative Electrode Preink In the application / drying step 225 of negative electrode preink, the same operation as the application / drying step 205 of positive electrode preink may be performed. That is, the negative electrode pre-ink is applied to the current collector and dried in the same manner as described in the positive electrode ink application / drying / pressing / cutting step 109 and the negative electrode ink application / drying / pressing / cutting step 129.

  In this step, it is desirable to carry out in an atmosphere having a moisture content of 20 ppm or less, or in an atmosphere that does not come into contact with air or the like. This is because, even if the gas generated at the time of the initial charge of the battery is extracted in advance, water and atmospheric gas components are mixed in the ink, but a small amount of the gas generated at the time of the initial charge of the battery. This is because there is a possibility that it becomes a cause.

  First, as the applying step 225a, a negative electrode pre-ink is applied on a current collector (or an appropriate base material) by an appropriate method.

  Type, thickness, description of base material, negative electrode pre-ink application method (including ink-jet application method), negative electrode pre-ink viscosity, droplet diameter, between adjacent droplet centers The distance is the same as that described in the negative electrode pre-ink application / drying step 205. That is, the type, thickness, and description of the current collector described in the positive ink application step 109a, the positive electrode ink application method (including the ink jet method), the positive ink viscosity, This can be done in the same manner as the particle size and the distance between the centers of adjacent droplets. Therefore, explanation here is omitted.

  Next, in the drying step 225b after application of the negative electrode pre-ink, the negative electrode pre-ink applied on the current collector (or substrate) is dried under appropriate drying conditions to form a negative electrode.

  The drying conditions can be the same as the drying conditions described in the positive ink drying step 109b and the negative ink drying step 129b of the first embodiment, and thus description thereof is omitted here.

(Iv) Binder Solution Application / Drying Step to Negative Electrode In the binder solution application / drying step 227 to the negative electrode, first, a binder solution is prepared. The binder solution may contain a binder, a solvent for adjusting viscosity, an additive, and the like.

  The binder, the viscosity adjusting solvent, and the additive are the same as those in the step of applying / drying the binder solution to the positive electrode. That is, since the same binder, viscosity adjusting solvent and additive described in the positive electrode ink preparation step 107 of the first embodiment can be used, description thereof is omitted here.

  The blending amount of the binder, viscosity adjusting solvent, additive, etc. in the binder solution should be determined in consideration of the intended use of the battery (emphasis on output, emphasis on energy, etc.).

  Next, in the binder solution application step 227a to the negative electrode, the prepared binder solution is applied to the negative electrode prepared in (iii) by an appropriate method.

  The binder solution coating method (including the ink jet method), the binder solution viscosity, the droplet diameter, and the distance between the centers of adjacent droplets are the steps of applying and drying the binder solution on the positive electrode. This is the same as described in step 207. That is, it can be performed in the same manner as the positive electrode ink application method, the positive electrode pre-ink viscosity, the droplet diameter, and the distance between adjacent droplet centers described in the positive ink application step 109a. Therefore, explanation here is omitted.

  Next, in the drying step 227b after application of the binder solution, the binder solution applied on the negative electrode is dried under appropriate drying conditions.

  The drying conditions are the same as described in the drying step 207. That is, it can be performed in the same manner as the drying conditions described in the positive ink drying step 109b. Therefore, explanation here is omitted.

  This step 227 is also preferably performed in an atmosphere having a moisture content of 20 ppm or less, or in an atmosphere that does not come into contact with air or the like.

(V) Negative electrode pressing / cutting step In the negative electrode pressing / cutting step 229, the negative electrode applied and dried in the above step 227 is first pressed as the pressing step 229a after the binder solution is applied and dried. desirable. By performing this pressing operation, the surface of the obtained negative electrode can be further flattened. The apparatus and conditions used for the press operation are not particularly limited, and conventionally known apparatuses and methods can be appropriately used.

  Furthermore, in an industrial production process, as a cutting step 229b after pressing, in order to improve productivity, a negative electrode larger than the final battery size is produced and cut into a predetermined size. A process may be adopted.

(Vi) Pregel application process to negative electrode In the pregel application process 231 to the negative electrode, it is desirable to apply and cure the pregel solution to the positive electrode after the negative electrode pressing / cutting process 229.

  The pregel application step 231 on the negative electrode can be performed in the same manner as the pregel application step 211 on the positive electrode. That is, since it is the same operation as the pregel application process 111 to a positive electrode, description here is abbreviate | omitted.

  Since the following steps (3) and (4) are the same as steps (3) and (4) described in the first embodiment, description thereof is omitted here.

  That is, (3) the pregel solution preparation step 241 in the polymer electrolyte layer formation step and the pregel solution application step 243 on the separator are described in the pregel solution preparation step 141 and the pregel solution application step 143 on the separator. It is the same. Therefore, explanation here is omitted.

  (4) The positive electrode, negative electrode, polymer electrolyte layer assembling step 251, recharging step 253, and aging / inspection step 255 in the battery manufacturing step are the positive electrode, negative electrode, polymer electrolyte layer assembling step 151, recharging step 153, and aging. The same as described in the inspection step 155. Therefore, explanation here is omitted.

  The above is the description of a typical embodiment of the method for producing a lithium polymer battery according to the present invention, but the present invention is not limited to the above embodiment.

  For example, in the formation of the polymer electrolyte layer, as a preferred example, in both the first and second embodiments, a polymer electrolyte layer is formed by impregnating and applying a pregel solution to a separator and curing it to retain a polymer gel electrolyte. Is shown. However, in the present invention, the electrolyte layer may be formed without using a separator.

  For example, when (i) an all solid polymer electrolyte is formed, for example, a solution prepared by dissolving a raw polymer of the all solid polymer electrolyte, a lithium salt, or the like in a solvent such as NMP is used. It is manufactured by applying on a material and curing.

  (Ii) In the case of forming a polymer gel electrolyte layer, for example, as a raw material for the polymer gel electrolyte, a pregel solution comprising a host polymer and an electrolytic solution, a lithium salt, a polymerization initiator and the like is placed on a suitable substrate. It is produced by coating and polymerizing (accelerating the crosslinking reaction) simultaneously with heat drying in an inert atmosphere.

  (Iii) When using an all-solid polymer electrolyte layer in which an all-solid polymer electrolyte is held in a separator, for example, as a raw material for the all-solid polymer electrolyte, a host polymer, an electrolytic solution, a lithium salt, a polymerization initiator Etc. are prepared in a viscosity adjusting solvent. Next, the separator is impregnated with the prepared solution and polymerized (accelerating the crosslinking reaction) simultaneously with heat drying in an inert atmosphere.

  Formation of the electrolyte layer can also be performed by the above (i) to (iii).

  For example, an electrolyte layer laminated between the electrodes or a part thereof (an electrolyte film having about half the thickness of the electrolyte layer) is formed. An all-solid polymer electrolyte layer / membrane having an electrolyte layer / membrane or separator holding an all-solid polymer electrolyte is coated with the above solution or pregel solution on a suitable film such as PET and dried in an inert atmosphere. Manufactured by promoting the crosslinking reaction simultaneously with curing or heat drying. Or you may manufacture by impregnating and apply | coating the said solution or pregel solution to a suitable separator, and promoting a crosslinking reaction simultaneously with hardening or heat-drying in inert atmosphere.

  Alternatively, in order to perform the next battery assembly step simultaneously with the formation of the polymer electrolyte layer, the prepared solution or pregel solution is directly applied on the positive electrode and / or the negative electrode, and the polymer electrolyte layer having a predetermined thickness or the A part (an electrolyte membrane having about half the thickness of the electrolyte layer) is formed. Thereafter, the substrate or electrode on which the electrolyte layer / membrane is laminated is cured or heated and dried in an inert atmosphere at the same time as polymerization (accelerating the crosslinking reaction) to increase the mechanical strength of the electrolyte. A film may be formed by laminating on the electrode.

  A vacuum drier (vacuum oven) or the like can be used for the drying / curing or heat drying. The conditions for heat drying are determined according to the above solution or pregel solution and cannot be uniquely defined, but are usually 30 to 110 ° C. and 0.5 to 12 hours.

  The thickness of the electrolyte layer / membrane can be controlled using a spacer or the like. In the case of using a photopolymerization initiator, it is poured into a light transmissive gap, irradiated with ultraviolet rays using an ultraviolet irradiation device capable of drying and photopolymerization, and the polymer in the electrolyte layer is photopolymerized to carry out a crosslinking reaction. It is good to advance and form a film. However, it is needless to say that the method is not limited to this. Depending on the type of polymerization initiator, radiation polymerization, electron beam polymerization, thermal polymerization, etc. are used properly.

  In addition, since the film used in the substrate may be heated to about 80 ° C. in the production process, it has sufficient heat resistance at the temperature, and has no reactivity with the solution or the pregel solution. In view of the necessity of peeling and removing during the manufacturing process, it is desirable to use a material having excellent releasability. For example, a film made of PET or PP can be used, but it should not be limited to these.

  About the composition component of the said solution or pregel solution, its compounding quantity, etc., it should be suitably determined according to the intended purpose.

  Next, the lithium polymer battery according to the present invention is obtained by the above-described manufacturing method. In the lithium polymer battery according to the present invention, the amount of gas generated when the battery is initially charged can be reduced. It is also possible to prevent the reversible capacity from being reduced due to trapping of the active material-derived Li ions at the irreversible capacity site. Therefore, the amount of gas generated at the time of initial charge can be significantly reduced, and the high charge / discharge performance set at the time of battery manufacture can be maintained over a long charge / discharge cycle without greatly reducing at the time of initial charge.

  The type of the lithium polymer battery of the present invention is not particularly limited.

  For example, when distinguished by the structure of the battery, it is not particularly limited, such as a stacked (flat) battery or a wound (cylindrical) battery, and can be applied to any conventionally known structure. It is. Preferably, it is a stacked type (flat type) battery. This is because, in a wound type battery, the electrolyte layer is also subjected to tensile stress in the winding direction, and thus the strength in that direction is required, but in the laminated type, the strength in that direction is not required compared to the wound type. Because.

  Similarly, when the battery is distinguished by the type of the polymer electrolyte layer of the battery, it should not be particularly limited as long as it is a polymer battery using a polymer electrolyte for the electrolyte layer. That is, the present invention can be applied to both a polymer gel electrolyte type battery using a polymer gel electrolyte as an electrolyte layer and an all solid polymer electrolyte type battery using an all solid polymer electrolyte as an electrolyte layer. The all solid polymer electrolyte type battery is excellent in that a liquid leakage does not occur, and there is no problem of a liquid junction, the reliability is high, and a battery having excellent output characteristics can be formed with a simple configuration. In addition, polymer gel electrolyte type batteries have high ionic conductivity and are unlikely to leak, and the problem of liquid junctions can be eliminated by providing an insulating seal layer, providing high reliability and simple output characteristics. It is excellent in that an excellent battery can be formed.

  Similarly, in terms of the electrical connection form (electrode structure) in the battery, it is applicable to both non-bipolar (internal parallel connection type) batteries (general batteries) and bipolar (internal series connection type) batteries. It is possible. When stacking non-bipolar general batteries, lead wires are taken from each of the positive electrode and the negative electrode and connected to the adjacent battery via the lead wires. For this reason, the path of electron conduction corresponding to the length of the lead wire becomes long, and the output of the battery becomes low. On the other hand, in a bipolar battery, current flows through the electrode stacking method through a current collector. Therefore, compared to a non-bipolar battery, the current flowing distance is short and the cross-sectional area of the current flowing portion is also small. Since it is large, the path of electron conduction is remarkably shortened and loss can be reduced. This is because the output is increased accordingly. Therefore, the battery voltage is higher than that of a non-bipolar battery, and a battery having excellent capacity and output characteristics can be configured.

  When viewed in terms of battery electrode material or metal ions moving between electrodes, it is a lithium ion battery. This is because in a lithium ion battery, the voltage of one electrode unit (also referred to as a cell or a single battery layer) is large, high energy density and high output density can be achieved, and it is excellent as a vehicle driving power source or an auxiliary power source. It is. However, the present invention is not limited to lithium ion batteries as long as the gas generation at the time of initial charging of the battery can be reduced by precharging / discharging, the sodium ion battery, the potassium ion battery, the nickel hydrogen battery. The present invention can be applied to any conventionally known electrode material such as a battery, a nickel cadmium battery, and a nickel metal hydride battery.

  The battery of the present invention can be applied to both a primary battery and a secondary battery, but is convenient in that it can be repeatedly charged and discharged as a motor drive power source for a fuel cell, a hybrid vehicle, or the like. Therefore, it is desirable to apply to a secondary battery.

  Therefore, in the following description, a laminated bipolar bipolar ion polymer secondary battery will be described as an example, but the lithium polymer battery of the present invention should not be limited to these.

  Hereinafter, a preferred embodiment of a lithium ion battery according to the present invention will be described with reference to the drawings.

  4 to 7 schematically illustrate the basic configuration of a stacked bipolar lithium ion polymer secondary battery (hereinafter simply referred to as a bipolar battery), which is one of the preferred embodiments of the lithium ion battery of the present invention. To do. FIG. 4 is a schematic sectional view schematically showing the structure of the bipolar electrode constituting the bipolar battery. FIG. 5 is a schematic cross-sectional view schematically showing the structure of a battery element (hereinafter also simply referred to as a single cell layer) in which a positive electrode and a negative electrode that can insert and desorb lithium ions are sandwiched between electrolyte layers constituting a bipolar battery. The figure is shown. FIG. 6 is a schematic sectional view schematically showing the entire structure of the bipolar battery. FIG. 7 is a schematic diagram conceptually showing (symbolized) that a plurality of unit cell layers stacked in a bipolar battery are connected in series.

  As shown in FIG. 4, in the bipolar battery of the present invention, as shown in FIGS. 4 to 7, a positive electrode 12 is provided on one surface of one current collector 11, and a negative electrode 13 is provided on the other surface. The positive electrode 12 and the negative electrode 13 of the bipolar electrode 15 adjacent to each other with the electrolyte layer 14 sandwiched between the bipolar electrode 15 are opposed to each other. That is, in the bipolar battery 21, an electrode having a structure in which a plurality of bipolar electrodes 15 having the positive electrode 12 on one surface of the current collector 11 and the negative electrode 13 on the other surface are stacked via the electrolyte layer 14. A laminate (battery element part) 17 is formed. The uppermost and lowermost electrodes (current extraction electrodes) 15a and 15b of the electrode laminate 17 may have a structure in which electrodes (positive electrode 12 or negative electrode 13) on only one side necessary for the current collector 11 are formed. Good (see FIG. 6). The current extraction electrodes 15a and 5b can also be regarded as a kind of bipolar electrode. In the bipolar battery 21, positive and negative electrode leads 18 and 19 are joined to the current collector 11 or the high voltage tab of the uppermost and lowermost electrodes, respectively.

  The number of stacked bipolar electrodes is adjusted according to the desired voltage. If sufficient output can be ensured even if the thickness of the sheet-like battery is made as thin as possible, the number of laminated bipolar electrodes may be reduced.

  Further, in the bipolar battery 21, in order to prevent external impact and environmental degradation during use, the electrode laminate 17 portion is sealed under reduced pressure in the battery exterior material 20, and the electrode leads 18 and 19 are connected to the battery exterior material 20. A structure taken out to the outside is preferable (see FIGS. 6 and 7). From the viewpoint of weight reduction, a polymer-metal composite laminate film is used for the outer packaging material 20, and a part or all of the peripheral portion thereof is joined by thermal fusion, so that the electrode laminate 7 is accommodated and sealed under reduced pressure. It is preferable that the electrode leads 18 and 19 be taken out of the exterior material 20 (sealed). As shown in FIG. 7, the basic configuration of the bipolar battery 21 can be said to be a configuration in which battery elements (single cell layers (single cells)) 16 having a positive electrode and a negative electrode facing each other with an electrolyte layer interposed therebetween are connected in series. It is.

  Hereinafter, although it demonstrates easily for every component of the battery of this invention, it cannot be overemphasized that this invention should not be restrict | limited to these at all. That is, in the present invention, the laminated bipolar lithium ion polymer secondary battery, which is one of the preferred embodiments described in FIGS. 4 to 7, and the components of the non-bipolar lithium ion polymer secondary battery are: It is the same except for the electrical connection form (electrode structure) in the battery. Therefore, it will be described collectively below. However, it goes without saying that the present invention should not be limited to these.

[Current collector]
Since the current collector is as already described in the section of the method for producing a lithium polymer battery according to the present invention, description thereof is omitted here.

[Positive electrode layer]
Since the positive electrode layer is also as described in the section of the method for producing a lithium polymer battery according to the present invention, the description thereof is omitted here.

[Negative electrode layer]
Since the negative electrode layer is as described in the section of the method for producing a lithium polymer battery according to the present invention, description thereof is omitted here.

[Polymer electrolyte layer]
Further, the electrolyte layer of the present invention is not particularly limited. Depending on the purpose of use, any of (a) a polymer gel electrolyte layer, (b) an all solid polymer electrolyte layer or (c) a polymer electrolyte layer comprising a separator (including a nonwoven fabric separator) impregnated with these polymer electrolytes It can also be applied to.

  Here, since the polymer electrolyte layer (c) is the same as that described in the section of the method for producing a lithium polymer battery according to the present invention, the description thereof is omitted here.

(A) Polymer gel electrolyte layer The polymer gel electrolyte layer may be any electrolyte layer that does not use a separator made of the polymer gel electrolyte described in the section of the method for producing a lithium polymer battery according to the present invention. Description is omitted.

(B) All-solid polymer electrolyte layer The all-solid polymer electrolyte layer may be any electrolyte layer that does not use a separator made of a polymer solid electrolyte described in the section of the method for producing a lithium polymer battery according to the present invention. The description in is omitted.

  In addition, you may use together the polymer electrolyte layer of said (a)-(c) in one battery.

  The polymer electrolyte may be contained in the polymer electrolyte layer, the positive electrode layer, and the negative electrode layer, but the same polymer electrolyte may be used, or different polymer electrolytes may be used depending on the layer.

  By the way, a host polymer for a polymer electrolyte that is preferably used at present is a polyether polymer such as PEO and PPO. For this reason, the oxidation resistance on the positive electrode side under high temperature conditions is weak. Therefore, when using a positive electrode agent having a high oxidation-reduction potential that is generally used in solution-type lithium ion batteries, the capacity of the negative electrode is preferably smaller than the capacity of the positive electrode facing through the polymer electrolyte layer. If the capacity of the negative electrode is less than the capacity of the opposing positive electrode, it is possible to prevent the positive electrode potential from rising excessively at the end of charging. In addition, the capacity | capacitance of a positive electrode and a negative electrode can be calculated | required from manufacturing conditions as theoretical capacity | capacitance at the time of manufacturing a positive electrode and a negative electrode. You may measure the capacity | capacitance of a finished product directly with a measuring device.

  However, if the capacity of the negative electrode is smaller than the capacity of the opposing positive electrode, the negative electrode potential will be too low and the durability of the battery may be impaired, so it is necessary to pay attention to the charge / discharge voltage. For example, care should be taken not to lower the durability by setting the average charge voltage of one cell (single cell layer) to an appropriate value for the oxidation-reduction potential of the positive electrode active material. Specifically, as described in the section of the method for producing a lithium polymer battery according to the present invention, a negative charge / discharge capacity value after removing irreversible capacity using a precharge / discharge-treated electrode active material is used. It is desirable to design the positive electrode capacity balance to a predetermined value, desirably negative electrode capacity / positive electrode capacity = 1.0 to 1.2.

[Insulating seal layer]
In the case of a bipolar battery, the insulating seal layer (see reference numeral 14b in FIG. 6) may cause a short circuit due to contact between current collectors, leakage of electrolyte, or slight unevenness at the end of the laminated electrode. In order to prevent this, it is formed around each electrode.

  The insulating seal layer may be any layer having insulating properties, sealing performance against leakage of electrolyte solution or moisture permeation from the outside (sealing property), heat resistance under battery operating temperature, for example, epoxy Resin, rubber, polyethylene, polypropylene, and the like can be used, but an epoxy resin is preferable from the viewpoints of corrosion resistance, chemical resistance, ease of production (film forming property), economy, and the like.

[High-power tab]
In the case of a bipolar battery, the high voltage tab is attached to a current collector constituting the outermost layer electrode as necessary. When used, it has a function as a terminal and is preferably as thin as possible from the viewpoint of thinning. However, since the laminated positive electrode, negative electrode, polymer electrolyte layer, and current collector are all weak in mechanical strength, it is desirable that they have sufficient strength to sandwich and support them from both sides. Furthermore, it can be said that the thickness of the high-power tab is usually preferably about 0.1 to 2 mm from the viewpoint of suppressing the internal resistance of the high-power tab.

  As a material of the high voltage tab, a material used in a normal lithium polymer battery can be used. For example, aluminum, copper, titanium, nickel, stainless steel (SUS), and alloys thereof can be used. Aluminum is preferably used from the viewpoints of corrosion resistance, ease of production, economy, and the like.

  The material of the high-voltage tab for positive current extraction and the high-voltage tab for negative electrode may be the same material or different materials. Further, the high-voltage tabs on the positive electrode side and the negative electrode side may be formed by stacking different materials.

  The high-voltage tab on the positive electrode and negative electrode side may be the same size as the current collector, but is not particularly limited.

[Positive electrode and negative electrode lead]
As shown in FIG. 7, for the positive electrode lead 18 and the negative electrode lead 19, known leads that are usually used in lithium polymer batteries can be used. As the material of the positive electrode and the negative electrode lead, a material used in a normal lithium polymer battery can be used. For example, aluminum, copper, iron, titanium, nickel, stainless steel (SUS), alloys thereof, and the like can be used. Aluminum is preferably used from the viewpoints of corrosion resistance, ease of production, economy, and the like. From the viewpoint of suppressing an increase in resistance of the entire electrode lead, it is desirable to use Cu. Furthermore, a surface coating layer may be formed on the electrode lead in order to improve the adhesion of the battery exterior material to the polymer material. Ni can be most suitably used for the surface coating layer, but metal materials such as Ag and Au can be used as well. [Battery exterior material (battery case)]
In order to prevent external impact and environmental degradation when using a lithium polymer battery, in order to prevent external impact and environmental degradation during use, the entire battery stack is assembled as shown in FIG. (Battery case) 20 may be accommodated. As a battery exterior material, from the viewpoint of weight reduction, a polymer-metal composite laminate film (also simply referred to as a polymer-metal composite laminate film) such as an aluminum laminate pack in which a metal is coated with a polymer insulator is used. Conventionally known battery exterior materials are preferred.

  The polymer-metal composite laminate film is not particularly limited, and a conventionally known film in which a metal film is disposed between polymer films and the whole is laminated and integrated can be used. As specific examples, for example, an outer protective layer made of a polymer film (laminate outermost layer), a metal film layer, a heat-sealing layer made of a polymer film (laminate innermost layer), and the whole is laminated and integrated. The thing which becomes. Specifically, in the polymer-metal composite laminate film used for the exterior material, a heat-resistant insulating resin film is first formed as a polymer film on both surfaces of the metal film, and heat fusion is performed on at least one heat-resistant insulating resin film. An insulating insulating film is laminated. Such a laminate film is heat-sealed by an appropriate method, whereby the heat-welding insulating film portion is fused and joined to form a heat-sealing portion. An example of the metal film is an aluminum film. Moreover, as said insulating resin film, a polyethylene tetraphthalate film (heat-resistant insulating film), a nylon film (heat-resistant insulating film), a polyethylene film (heat-bonding insulating film), a polypropylene film (heat-bonding insulating film) ) Etc. can be illustrated. However, the exterior material of the present invention should not be limited to these.

  In such a polymer-metal composite laminate film, one-to-one (bag-like) laminate film is bonded easily and reliably using a heat-welding insulating film by ultrasonic welding or the like. be able to. Therefore, in the present invention, by using such a polymer-metal composite laminate film, a part or all of the peripheral portion thereof is joined by heat fusion, so that the battery stack is housed and sealed. preferable. In order to maximize the long-term reliability of the battery, metal films that are constituent elements of the polymer-metal composite laminate sheet may be directly joined. Ultrasonic welding can be used to join the metal films by removing or destroying the heat-fusible resin between the metal films.

  When a polymer-metal composite laminate film is used for the battery exterior material, the positive electrode and the negative electrode lead may be sandwiched between the heat fusion parts and exposed to the outside of the battery exterior material. In addition, it is preferable to use a polymer-metal composite laminate film having excellent thermal conductivity in that heat can be efficiently transferred from a heat source of an automobile and the inside of the battery can be quickly heated to the battery operating temperature.

  Next, in this invention, it can be set as the assembled battery comprised by connecting two or more said lithium polymer batteries. That is, the battery capacity and output for each purpose of use can be met by using an assembled battery in which at least two lithium polymer batteries (especially bipolar batteries) of the present invention are connected in series and / or in parallel. Therefore, it is possible to cope with relatively low cost.

  Specifically, for example, N bipolar batteries are connected in parallel, and N parallel bipolar batteries are further connected in series in a metal or resin battery case to form a battery pack. (N and M are integers of 2 or more). At this time, the number of series / parallel connections of the bipolar battery is determined according to the purpose of use. For example, as a large-capacity power source such as an electric vehicle (EV), a hybrid electric vehicle (HEV), a fuel cell vehicle, and a hybrid fuel cell vehicle, it can be applied to a power source for driving a vehicle that requires high energy density and high output density. What is necessary is just to combine. Moreover, what is necessary is just to electrically connect the positive electrode terminal and negative electrode terminal for assembled batteries, and the electrode lead of each bipolar battery using a lead wire. Further, when the bipolar batteries are connected in series / parallel, they may be electrically connected using an appropriate connecting member such as a spacer or a bus bar. This makes it possible to meet the demands for capacity and voltage for various vehicles with a combination of basic bipolar batteries. As a result, it becomes possible to facilitate the design selectivity of required energy and output. Therefore, it is not necessary to design and produce different bipolar batteries for various vehicles, and the basic bipolar battery can be mass-produced, and the cost can be reduced by mass production.

  Moreover, the assembled battery of this invention should not be restrict | limited to what was demonstrated above, A conventionally well-known thing can be employ | adopted suitably. For example, in the assembled battery of the present invention, the bipolar battery of the present invention and a general battery in which the bipolar battery and the positive and negative electrode materials are the same and the voltage is the same by connecting the number of structural units of the bipolar battery in series are arranged in parallel. It may be connected to.

  Examples of the general battery in which the bipolar battery and the positive and negative electrode materials are the same and the voltage is the same by connecting the number of structural units of the bipolar battery in series include a lithium ion polymer secondary battery which is preferably not a bipolar type. That is, the battery forming the assembled battery may be a mixture of the bipolar battery of the present invention and a general battery such as a non-bipolar lithium ion polymer secondary battery. As a result, an assembled battery that compensates for each other's weaknesses can be made by combining a bipolar battery that focuses on output and a general battery that focuses on energy, and the weight and size of the assembled battery can be reduced. The proportion of each bipolar battery and non-bipolar general battery to be mixed is determined according to the safety performance and output performance required for the assembled battery.

  The assembled battery of the present invention may be provided with various measuring devices and control devices according to the usage, for example, a voltage measuring connector may be provided to monitor the battery voltage, etc. There is no particular limitation.

  Further, in the present invention, a new assembled battery is produced to meet the requirements for battery capacity and output for each purpose of use by forming at least two or more of the above assembled batteries in series, parallel, or a series and parallel composite connection. Without having to do so, it becomes possible to cope with a relatively low cost. That is, such a composite battery is a battery in which at least two or more battery packs are connected in series, in parallel, or in series and parallel, and a standard battery pack is manufactured and combined to form a battery pack. The battery pack specifications can be tuned. Thereby, since it is not necessary to manufacture many assembled battery types with different specifications, the composite assembled battery cost can be reduced. In this way, a composite assembled battery in which a plurality of assembled batteries are connected in series and parallel can be repaired by simply replacing the failed part even if some of the batteries or the assembled battery fail. The assembled battery may include a battery composed of only the bipolar battery of the present invention, or a battery composed of the bipolar battery of the present invention and another non-bipolar battery.

  In the present invention, it is possible to provide a vehicle in which the lithium polymer battery and / or the assembled battery (including the composite assembled battery) is mounted as a driving power source. The lithium polymer battery and / or the assembled battery of the present invention has various characteristics as described above, and is particularly a compact battery. For this reason, it is suitable as a driving power source for vehicles that are particularly demanding in terms of energy density and power density, such as electric vehicles, hybrid electric vehicles, fuel cell vehicles, and hybrid fuel cell vehicles. For example, it is convenient to install an assembled battery as a driving power source under the seat at the center of the body of an electric vehicle or hybrid electric vehicle because a large interior space and trunk room can be obtained. The present invention should not be limited to these, and may be mounted in the lower part of the rear trunk room, or if the engine is not mounted like an electric vehicle or a fuel cell vehicle, the engine in front of the vehicle body It can also be mounted on parts that had been mounted. In the present invention, not only the assembled battery but also a bipolar battery may be mounted depending on the intended use, or a combination of these assembled battery and bipolar battery may be mounted. In addition, as a vehicle on which the bipolar battery and / or the assembled battery of the present invention can be mounted as a driving power source, the above-described electric vehicle, hybrid electric vehicle, fuel cell vehicle, and hybrid fuel cell vehicle are preferable, but these are not limited thereto. Is not to be done.

  The present invention will be described in more detail using the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples.

  The manufacturing method of the battery of Examples 1-3, the comparative example 1, and the reference example 1 is shown below. These batteries were produced according to the steps shown in FIG.

(1) Pre-ink preparation process (i) Positive electrode pre-ink preparation process Positive electrode pre-ink preparation was performed as follows. After thoroughly mixing 95% by mass of LiMn ₂ O ₄ having an average particle diameter of 1 μm as a positive electrode active material and 5% by mass of acetylene black having a particle diameter of 50 nm as a conductive material, 1.0M LiPF ₆ of a lithium salt and an organic solvent as an electrolytic solution EC + PC + DMC (EC: PC: DMC (volume ratio) = 1: 1: 3) of (plasticizer) was added and stirred sufficiently to prepare a positive electrode pre-ink.

(Ii) Production process of negative electrode pre-ink The production of negative electrode pre-ink was performed as follows. Graphite having an average particle diameter of 10 μm as the negative electrode active material, 1.0M LiPF _{6 of} lithium salt and EC + PC + DMC of organic solvent (plasticizer) as the electrolyte (EC: PC: DMC (volume ratio) = 1: 1: 3) Was added and sufficiently stirred to prepare a negative electrode pre-ink.

(2) Pre-charge / pre-discharge step (i) Pre-charge / pre-discharge step of positive electrode pre-ink The positive-electrode pre-ink is sealed in the pre-charge device 201 shown in FIG. 2, and a constant current / constant-voltage charge of ²⁰ μA / cm ² is set to the upper limit voltage. Then, a constant current discharge of ²⁰ μA / cm ² was performed at a lower limit voltage of 2.5V.

(Ii) Pre-charging / pre-discharging step of negative electrode pre-ink The negative electrode pre-ink is sealed in the pre-charging device 201 shown in FIG. 2, and constant current / constant-voltage charging of ²⁰ μA / cm ² is performed at a lower limit voltage of 0 V, and then 20 μA / cm. ² constant current discharge was performed with the upper limit voltage of 2.5V.

(3) Degassing step (i) Positive electrode degassing step The positive electrode pre-ink that has been precharged / predischarged is removed in a reduced-pressure atmosphere to remove gas generated with precharge / predischarge (initial charge / initial discharge). did. At this time, the pressure was reduced while being vibrated with ultrasonic waves. After degassing, it was sealed in a sealed container under a reduced pressure atmosphere so as not to touch the outside air.

(Ii) Negative electrode degassing step The negative electrode pre-ink that had been precharged / predischarged was removed in a reduced-pressure atmosphere and the gas generated accompanying precharge / predischarge (initial charge / initial discharge) was removed. At this time, the pressure was reduced while being vibrated with ultrasonic waves. After degassing, it was sealed in a sealed container under a reduced pressure atmosphere so as not to touch the outside air.

(4) Cleaning / drying step (i) Positive electrode cleaning / drying step The positive electrode pre-ink subjected to the above degassing step is submerged in a solvent tank filled with DEC to elute the electrolyte (LiPF ₆ ) remaining in the pre-ink, and then again Vacuum drying was performed.

(Ii) Negative electrode cleaning / drying step The negative electrode pre-ink subjected to the above degassing step was submerged in a solvent tank filled with DEC to elute the electrolyte (LiPF ₆ ) remaining in the pre-ink, and then dried under reduced pressure again.

(5) Adjustment of electrode ink (i) Adjustment of positive electrode ink The positive electrode pre-ink obtained in the positive electrode cleaning / drying step was weighed with PVdF as a binder so as to have the composition of the following positive electrode ink, and dispersed by adding an appropriate amount of NMP. And adjusting the viscosity to be 100 cP to prepare a positive electrode ink. The composition of the obtained positive electrode ink was 85% by mass of LiMn ₂ O ₄ , 10% by mass of acetylene black, and 5% by mass of PVdF. Since the NMP is volatilized and removed when the electrode is dried, an appropriate amount is added so that the ink viscosity is not the material constituting the electrode. Therefore, the composition ratio of the positive electrode ink indicates a ratio converted with components excluding NMP of the viscosity adjusting solvent.

(Ii) Preparation of negative electrode ink The negative electrode pre-ink obtained in the negative electrode cleaning / drying step was weighed with PVdF as a binder so as to have the following negative electrode ink composition, dispersed in an appropriate amount of NMP, and a viscosity of 100 cP. In this way, a negative electrode ink was prepared. The composition of the obtained negative electrode ink was 90% by mass of graphite and 10% by mass of PVdF. Since the NMP is volatilized and removed when the electrode is dried, an appropriate amount is added so that the ink viscosity is not the material constituting the electrode. Therefore, the composition ratio of the negative electrode ink indicates a ratio converted with components excluding NMP of the viscosity adjusting solvent.

(6) Electrode ink application / drying / pressing process (i) Positive electrode ink application / drying / pressing process Using the ink-jet coating apparatus, the positive electrode ink prepared above is applied to a 20 m-thick Al foil to a specified basis weight. The positive electrode was prepared by repeating the application.

  In detail, it carried out with the following procedures using the prepared positive electrode ink and the commercially available inkjet printer. When the above positive electrode ink is used, there is a problem that the solvent dissolves the plastic parts in the ink introduction portion of the ink jet printer. Therefore, printing was performed with a printer with the following modifications. That is, the parts in the ink introduction part were replaced with metal parts, and ink was supplied directly from the ink reservoir to the metal parts. In addition, although the active material and the conductive material were uniformly dispersed in the positive electrode ink, the ink reservoir was always stirred using a rotating blade so that these particles did not settle down just in case. The inkjet printer was controlled by a commercially available computer and software. In this example, the coating was repeated so that the positive electrode layer had a thickness of 5 μm, which was not achieved in the past, by repeating the coating until the specified basis weight.

  First, positive ink was introduced into a modified ink jet printer, and a pattern created on a computer (in this example, printed and applied so as to fill the entire surface of the positive electrode forming part) was printed on the current collector. . After the printing application, drying was performed in a vacuum oven at 120 ° C. for 12 hours in order to dry the solvent. After drying, pressing was performed to form a positive electrode layer on the current collector.

(Ii) Application / drying / pressing step of negative electrode ink A negative electrode was prepared by repeatedly applying the negative electrode ink prepared above onto a SUS foil having a thickness of 20 μm to a specified basis weight using an inkjet coating apparatus.

  In detail, it carried out with the following procedures using the prepared negative electrode ink and the commercially available inkjet printer. When the above negative electrode ink is used, there is a problem that the solvent dissolves plastic parts in the ink introduction portion of the ink jet printer. Therefore, printing was performed with a printer with the following modifications. That is, the parts in the ink introduction part were replaced with metal parts, and ink was supplied directly from the ink reservoir to the metal parts. Further, although the active material was uniformly dispersed in the negative electrode ink, the ink reservoir was always stirred using a rotary blade so that the active material particles did not settle. The inkjet printer was controlled by a commercially available computer and software. In this example, the coating was applied so as to obtain a thin film having a negative electrode layer thickness of 5 μm, which could not be achieved in the past, by repeating the coating to a specified basis weight.

  First, a negative electrode ink was introduced into a modified ink jet printer, and a pattern created on a computer (in this example, printed and applied so as to fill the entire surface of the negative electrode forming portion) was printed and applied on a current collector. . After the printing application, drying was performed in a vacuum oven at 120 ° C. for 12 hours in order to dry the solvent. After drying, pressing was performed with a roll press to form a negative electrode layer on the current collector.

  In this example, using the positive electrode and negative electrode active material precharged / discharged by the above-described manufacturing method, the capacity balance of the negative electrode / positive electrode using the value of the reversible capacity after removing the irreversible capacity, the negative electrode capacity / positive electrode capacity = It was designed to be 1.

(7) Production process of polymer electrolyte layer A pregel solution shown below is immersed in a porous membrane separator of PP / PE / PP three-layer structure having a thickness of 12 μm and a porosity of 50% as a separator, and in an inert atmosphere. A polymer electrolyte layer having a thickness of 30 μm was formed by thermal polymerization at 90 ° C. for 1 hour to hold the polymer gel electrolyte in the separator.

The pregel solution used was composed of a polymer [5% by mass], an electrolytic solution + lithium salt [95% by mass], and a polymerization initiator [0.1% by mass with respect to the polymer]. Here, as the polymer, a copolymer of polyethylene oxide and polypropylene oxide (a copolymerization ratio of 5: 1 and a weight average molecular weight of 8000 was used. As an organic solvent of the electrolytic solution, EC + DMC (EC: DMC (volume ratio) = 1: 3) 1.0M Li (C ₂ F ₅ SO ₂ ) ₂ N was used as the lithium salt of the electrolyte. 1.0 M. The AIBN was used as the polymerization initiator.

(8) Battery Assembly Next, the polymer electrolyte layer and the negative electrode were sequentially laminated on the positive electrode, and housed in a laminate pack as a battery outer packaging material to obtain a polymer gel electrolyte type lithium polymer battery.

  A battery manufactured by performing all the steps described above is referred to as Example 1, and other Examples 2 to 3, Comparative Example 1, and Reference Example 1 are performed by omitting some of the steps as shown in Table 1. It was.

  A battery produced by omitting the cleaning and drying steps for both the positive electrode and the negative electrode was taken as Example 2. A battery produced by omitting the degassing step and the cleaning / drying step for both the positive electrode and the negative electrode was taken as Example 3. A battery prepared by omitting the precharge / predischarge step and the degassing step for both the positive electrode and the negative electrode was used as Reference Example 1. A battery prepared by omitting the precharge / predischarge step, the degassing step, and the cleaning / drying step for both the positive electrode and the negative electrode was used as Comparative Example 1.

(Battery evaluation test)
Using the batteries of Examples 1 to 3, Reference Example 1 and Comparative Example 1, output characteristics were compared.

  In the output characteristic test, charging was performed at a 1C rate, and discharging was performed at a 1C rate, a 10C rate, and a 50C rate. The obtained results are shown in Table 2. Here, at the 1C rate, the battery was charged at a constant current to 4.2 V, paused for 10 minutes, discharged at a constant current of 1 C to 2.5 V, and one cycle from the 10-minute pause. During the test, the temperature was not controlled and the test was performed in a room temperature (about 25 ° C.) environment. Here, at a 10 C rate, the battery was discharged to 2.5 V at a 10 C constant current. At the 50 C rate, the battery was discharged to 2.5 V at a constant current of 50 C.

  The numerical value (%) at each rate in Table 2 is that the output characteristics of the battery of Comparative Example 1 (conventional example) is 100% (reference).

  From the results of Table 2 above, it was found that in Comparative Example 1, gas was generated at the time of initial charge as in the conventional case, and the gas could not be removed, so that sufficient output characteristics could not be obtained as compared with the present invention. In particular, as the C rate increases (that is, when charging / discharging with a large current), the difference in output characteristics from this example becomes more prominent. It can be said that charging / discharging with a large current increases the amount of gas generated and decreases the charging / discharging performance.

  Among the examples, the battery of Example 1 was extremely excellent, and then the battery of Example 2 was excellent. From this, it was found that it is most effective to carry out all the steps described above. Further, it was confirmed that the battery of Example 2 omitting the cleaning process can exhibit high output characteristics as in Example 1. On the other hand, in Example 3 in which the precharging / pre-discharging process was performed without performing the cleaning / drying process and the degassing process, the output characteristics were significantly reduced as compared with Examples 1 and 2. From this, it was found that the combined use of the degassing step in addition to the precharge / predischarge step is an extremely effective and effective combination, and thereby a remarkable output improvement effect can be exhibited. Further, in Reference Example 1 in which the precharge / predischarge process and the degassing process were not performed, there was no difference in output characteristics from that of Comparative Example 1, and therefore the cleaning / drying process alone could not be an effective solution. It has been found that a synergistic effect can be expressed for the first time by combining with the precharge / predischarge process and the degassing process of the present invention.

  In addition, although the battery was produced according to the process shown in FIG. 3, the result was almost the same as the output characteristics of the battery produced by the manufacturing method shown in FIG.

It is drawing which shows the process flowchart of typical embodiment (it is also called 1st Embodiment) of the manufacturing method of the lithium polymer battery of this invention. It is the schematic sectional drawing which represented typically one Embodiment of the apparatus used for the pre-charge of the electrode pre-ink of this invention, degassing, and pre-discharge. It is drawing which shows the process flowchart of typical embodiment (it is also called 2nd Embodiment) of the manufacturing method of the lithium polymer battery of this invention. It is the cross-sectional schematic which represented typically the basic structure of the bipolar electrode which comprises the bipolar battery of this invention. It is the cross-sectional schematic which represented typically the basic structure of the single battery layer (single cell) which comprises the bipolar battery of this invention. 1 is a schematic cross-sectional view schematically showing a basic structure of a bipolar battery of the present invention. It is the schematic which represents the basic composition of the bipolar battery of this invention typically.

Explanation of symbols

11 Current collector,
12 positive electrode,
13 negative electrode,
14 electrolyte layer,
15 bipolar electrodes,
15a An electrode having a positive electrode layer disposed only on one side of the current collector,
15b An electrode having a negative electrode layer disposed only on one side of the current collector,
16 Single battery layer (single cell),
17 electrode laminate,
18 Positive lead,
19 Negative lead,
20 Battery exterior material,
21 Bipolar lithium ion secondary battery,
201 Equipment used for pre-charging, degassing and pre-discharging,
203 Pre-ink storage container,
205 Pre-ink storage container lid,
207 separator,
101 'pre-ink,
103 'active material,
105 'Conductive material.

Claims (7)

  A method for producing a lithium polymer battery, wherein initial charge / discharge (pre-charge / pre-discharge) is performed in an ink state before applying an electrode active material to a current collector foil.   A method for producing a lithium polymer battery, characterized by performing initial charge / discharge (pre-charge / pre-discharge) in an ink state and degassing before applying an electrode active material to a current collector foil.   2. The negative electrode / positive electrode capacity balance is designed to be a predetermined value using the reversible capacity value after removing the irreversible capacity using the electrode active material pre-charged / discharged by the above-mentioned manufacturing method. Or the manufacturing method of the lithium polymer battery of 2.   The method for producing a lithium polymer battery according to any one of claims 1 to 3, wherein the electrode active material precharged / discharged by the above production method and the binder solution are separately applied.   In the said manufacturing method, an ultrasonic wave is applied to a degassing process, The manufacturing method of the lithium polymer battery of any one of Claims 1-4 characterized by the above-mentioned.   The method for producing a lithium polymer battery according to any one of claims 1 to 5, wherein the electrode active material precharged / discharged by the above production method is applied under reduced pressure.   It is obtained by the manufacturing method of any one of Claims 1-6, The lithium polymer battery characterized by the above-mentioned.

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