JP4529516B2 - Power supply - Google Patents

Description

  The present invention relates to a power source, and more particularly to a power source provided with a lithium ion secondary battery.

Conventionally, a power source including a lithium ion secondary battery that can be repeatedly charged and discharged has been widely used in devices such as portable terminals. When using such a power supply, it is desirable to accurately grasp the remaining capacity of the lithium ion secondary battery. And as a method of acquiring the remaining capacity of the lithium ion secondary battery, it is acquired by numerical calculation based on the preset charge / discharge characteristics of the lithium ion secondary battery and the charge / discharge history of the lithium ion secondary battery. There is a known method (see, for example, Patent Document 1).
Japanese Patent No. 3346003

  However, such a method is complicated because it requires acquisition of the charge / discharge history of the lithium ion secondary battery. Therefore, there is a need for a simpler method for determining the remaining capacity.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a power supply capable of easily grasping the remaining capacity of a lithium ion secondary battery.

The power source according to the present invention includes a laminated structure in which a positive electrode layer containing a positive electrode active material, a separator layer, and a negative electrode layer containing a negative electrode active material are laminated in this order, an electrolyte, and a flexible structure that seals the laminated structure and the electrolyte. A lithium ion secondary battery having a container, and a laminated structure stacked on the outer side of the container of the lithium ion secondary battery so as to face the laminated structure in the stacking direction of the laminated structure. A pressure sensor in which the area of the surface facing the stacking direction of the body is equal to or greater than the area of the surface of the positive electrode layer or the negative electrode layer facing the surface, and the lithium ion secondary battery and the pressure sensor. And a sandwiching member sandwiched from both sides in the direction in which the sensors overlap. The lithium ion secondary battery includes an electrolyte containing lithium ions, a positive electrode active material, and a negative electrode active material, and at least one of the positive electrode active material and the negative electrode active material can intercalate and deintercalate the lithium ions. It is.

  In general, when lithium ions are intercalated into the negative electrode active material during charging of the lithium ion secondary battery, the negative electrode active material expands, and when lithium ions are deintercalated from the positive electrode active material, the positive electrode active material contracts. In addition, when lithium ions are deintercalated from the negative electrode active material during discharge, the negative electrode active material contracts, whereas when lithium ions are intercalated into the positive electrode active material, the positive electrode active material expands.

  When either the positive electrode active material or the negative electrode active material intercalates and deintercalates lithium ions, the positive electrode active material or the negative electrode active material depends on the degree of charge, that is, the remaining capacity of the battery. One of them expands and contracts, and the volume of the lithium ion secondary battery changes.

  In addition, even when both the positive electrode active material and the negative electrode active material intercalate and deintercalate lithium ions, the positive electrode active material and the negative electrode active material are different from each other in terms of materials and structures. The degree of expansion / contraction associated with deintercalation differs from each other, and the expansion / contraction of the positive electrode active material and the expansion / contraction of the negative electrode active material are not completely eliminated. Accordingly, even in this case, the volume of the lithium ion secondary battery expands and contracts according to the degree of charge, that is, the remaining capacity of the battery.

  And according to the power supply of this invention, the lithium ion secondary battery and the pressure sensor are pinched | interposed from the both sides of the direction which accumulated these lithium ion secondary batteries and the pressure sensor with the clamping member. Therefore, when the lithium ion secondary battery expands and contracts, the force applied to the pressure sensor changes correspondingly, and the change in the volume of the lithium ion secondary battery can be detected as the output value of the pressure sensor. Then, the remaining capacity of the lithium ion secondary battery can be estimated based on the output value of the pressure sensor.

Then, the power supply according to the present invention has the above-described structure, so that the expansion and contraction of the lithium ion secondary battery caused by the expansion and contraction in the thickness direction of the positive electrode layer including the positive electrode active material and the negative electrode layer including the negative electrode active material is detected by the pressure sensor. Therefore, the remaining capacity of the lithium ion secondary battery can be obtained with higher accuracy. In addition, the electrolyte is less likely to leak from the lithium ion secondary battery, and the life of the pressure sensor is improved.

  In addition, a spacer is interposed between at least one of the pressure sensor and the holding member, the pressure sensor and the lithium ion secondary battery, and the lithium ion secondary battery and the holding member. It is preferable.

  By interposing such a spacer, it becomes easy to fix the lithium ion secondary battery and the pressure sensor with no gap in the overlapping direction by the sandwiching member. Therefore, a power source capable of acquiring the remaining capacity with high accuracy can be easily manufactured.

  As such a pressure sensor, for example, a piezoelectric element that outputs a change in pressure (stress) as a change in electromotive force, a strain gauge that outputs a change in pressure as a change in resistance value, or the like is preferably used.

  In the lithium ion secondary battery, the negative electrode active material can intercalate and deintercalate lithium ions, and the negative electrode active material preferably contains Si.

  Since the negative electrode active material having such a configuration has a particularly high expansion / contraction rate due to intercalation and deintercalation of lithium ions, the remaining capacity can be obtained with extremely high accuracy.

  ADVANTAGE OF THE INVENTION According to this invention, the power supply which can grasp | ascertain the remaining capacity of a lithium ion secondary battery simply is provided.

  Next, a specific embodiment of the present invention will be described with reference to FIGS.

  The power source 1 according to the present embodiment mainly includes a pressure sensor 60, a lithium ion secondary battery 5, a spacer 70, and a case (holding member) 90 that sandwiches the pressure sensor 60, the lithium ion secondary battery 5, and the spacer 70. With.

(Lithium ion secondary battery)
The lithium ion secondary battery 5 mainly includes a laminated structure 50 and a pack (battery container) 55 that accommodates the laminated structure 50 in a sealed state.

(Laminated structure)
The laminated structure 50 includes, in order from the top, a positive electrode current collector 40, a secondary battery element 35, a negative electrode current collector 45, a secondary battery element 35, and a positive electrode current collector 40, each having a plate shape. ing.

  The secondary battery element 35 is formed by laminating a cathode layer (positive electrode layer) 10, a separator layer 30, and an anode layer (negative electrode layer) 20 in this order.

  Here, in each secondary battery element 35, the positive electrode current collector 40 and the negative electrode current collector are arranged so that the anode layer 20 is in contact with the surface of the negative electrode current collector 45 and the cathode layer 10 is in contact with the surface of the positive electrode current collector 40. It is arranged between the bodies 45. Here, the anode and the cathode are determined based on the polarity at the time of discharging of the lithium ion secondary battery 5 for convenience of explanation. When the lithium ion secondary battery 5 is charged, the direction of charge flow is opposite to that during discharge, so that the anode and the cathode are interchanged.

(Anode layer)
The anode layer 20 is a layer containing a negative electrode active material, a conductive aid, a binder and the like. Hereinafter, the anode layer 20 will be described.

The negative electrode active material is not particularly limited as long as desorption (deintercalation) and insertion (intercalation) of lithium ions can reversibly proceed, and a known negative electrode active material can be used. Examples of such active materials include carbon materials such as natural graphite, artificial graphite, non-graphitizable carbon, graphitizable carbon, and low-temperature calcined carbon, and metals that can be combined with lithium such as Al, Si, and Sn. Alternatively, an alloy thereof, an amorphous compound mainly composed of an oxide such as SiO ₂ or SnO _2, or lithium titanate (Li ₄ Ti ₅ O ₁₂ ) can be given. Among them, it is preferable to use Si or an alloy thereof in order to increase the expansion / contraction rate associated with intercalation or deintercalation. Examples of the Si alloy include LiSi.

The conductive aid is not particularly limited as long as the conductivity of the anode layer 20 is improved, and a known conductive aid can be used. Examples thereof include carbon blacks, carbon materials, metal fine powders such as copper, nickel, stainless steel and iron, a mixture of carbon materials and metal fine powders, and conductive oxides such as ITO.

  The binder is not particularly limited as long as the negative electrode active material particles and the conductive auxiliary particles can be bound to the negative electrode current collector 45, and a known binder can be used. For example, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PEA), ethylene-tetrafluoro Fluorine resin such as ethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), polyvinyl fluoride (PVF), and styrene-butadiene rubber (SBR) Can be mentioned.

(Cathode layer)
The cathode layer 10 is a layer containing a positive electrode active material, a conductive aid, a binder and the like. Hereinafter, the cathode layer 10 will be described.

The positive electrode active material is not particularly limited as long as lithium ion desorption and insertion (intercalation) can reversibly proceed, and a known electrode active material can be used. For example, lithium cobalt oxide (LiCoO _2), lithium nickel oxide (LiNiO _2), lithium manganese spinel (LiMn ₂ O _4), and the general formula: represented by _{LiNi x Co y Mn z O 2} (x + y + z = 1) Composite metal oxide, lithium vanadium compound (LiV ₂ O ₅ ), olivine type LiMPO ₄ (where M represents Co, Ni, Mn or Fe), composite such as lithium titanate (Li ₄ Ti ₅ O ₁₂ ) A metal oxide is mentioned.

  As each component other than the positive electrode active material contained in the cathode layer 10, the same material as that constituting the anode layer 20 can be used. Also, the cathode layer 10 preferably contains the same electron conductive particles as the anode layer 20.

(Separator layer)
The separator layer 30 disposed between the anode layer 20 and the cathode layer 10 is formed from an electrically insulating porous body. The material of the separator layer 30 is not particularly limited, and a known separator material can be used. For example, as the electrically insulating porous body, at least one structure selected from the group consisting of a laminate of films made of polyethylene, polypropylene or polyolefin, a stretched film of a mixture of the above resins, or cellulose, polyester and polypropylene A fiber nonwoven fabric made of a material is mentioned.

  Here, as shown in FIG. 1, for each secondary battery element 35, the areas of the separator layer 30, the anode layer 20, and the cathode layer 10 are reduced in order, and the end face of the anode layer 20 is smaller than the end face of the cathode layer 10. The end face of the separator layer 30 protrudes outward from the end faces of the anode layer 20 and the cathode layer 10.

  As a result, even if each layer is slightly displaced in the direction intersecting the stacking direction due to an error in manufacturing, the entire surface of the cathode layer 10 can be made to face the anode layer 20 in each secondary battery element 35. It becomes easy. Accordingly, lithium ions released from the cathode layer 10 are sufficiently taken into the anode layer 20 through the separator layer 30. Furthermore, since the separator layer 30 is larger than the cathode layer 10 and the anode layer 20 and protrudes from the end surfaces of the cathode layer 10 and the anode layer 20, short circuit due to contact between the cathode layer 10 and the anode layer 20 is also reduced. .

(Negative electrode current collector)
The material of the negative electrode current collector 45 to be bonded to the anode layer 20 is not particularly limited as long as it is a metal material usually used as an anode current collector of a lithium ion secondary battery, and examples thereof include copper and nickel. As shown in FIGS. 1 and 2, one end of the negative electrode current collector 45 extends in a ribbon shape toward the outside to form a lead 45a.

(Positive electrode current collector)
The positive electrode current collector 40 bound to the cathode layer 10 is not particularly limited as long as it is a metal material usually used as a cathode current collector of a lithium ion secondary battery, and examples thereof include aluminum. One end of the positive electrode current collector 40 extends outward in a ribbon shape to form a lead 40a.

(Electrolyte solution)
The electrolyte solution is contained in the pores of the anode layer 20, the cathode layer 10, and the separator layer 30. The electrolyte solution is not particularly limited, and an electrolyte solution containing a lithium salt (electrolyte aqueous solution, electrolyte solution using an organic solvent) used for a known lithium ion secondary battery element can be used. However, the electrolyte aqueous solution is preferably an electrolyte solution (non-aqueous electrolyte solution) using an organic solvent because the electrochemical decomposition voltage is low, and the withstand voltage during charging is limited to a low level. As the electrolyte solution for the secondary battery element, a lithium salt dissolved in a non-aqueous solvent (organic solvent) is preferably used. Examples of the lithium salt that is a source of lithium ions include LiPF ₆ , LiClO ₄ , LiBF ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiCF ₃ , CF ₂ SO ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (CF ₃ CF ₂ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ), LiN (CF ₃ CF ₂ CO) _2, etc. are used. In addition, these salts may be used individually by 1 type, and may use 2 or more types together.

  Moreover, as an organic solvent, the solvent currently used for the known secondary battery element can be used. For example, propylene carbonate, ethylene carbonate, diethyl carbonate and the like are preferable. These may be used alone or in combination of two or more at any ratio.

  In the present embodiment, the electrolyte solution may be a gel electrolyte obtained by adding a gelling agent in addition to liquid. Further, instead of the electrolyte solution, a solid electrolyte (a solid polymer electrolyte or an electrolyte made of an ion conductive inorganic material) may be contained.

(pack)
As shown in FIG. 1, the pack 55 is formed by folding a rectangular flexible sheet in half at a substantially central portion in the longitudinal direction, and the laminated structure 50 is formed on both sides in the laminating direction (vertical direction). Is sandwiched between. Specifically, as shown in FIG. 2, among the end portions of the sheet 55s folded in half, three side seal portions 55b excluding the folded portion 55a are bonded by heat sealing or an adhesive, and a laminated structure The body 50 is sealed inside. The pack 55 prevents air and moisture from entering the pack 55 and prevents the electrolyte solution from leaking from the pack 55. In particular, as shown in FIG. 1, it is preferable to use a pack 55 formed of a sheet 55s having a three-layer structure. Specifically, the innermost layer 55h of the sheet 55s is a resin layer formed of a synthetic resin such as unstretched polypropylene (CPP), the intermediate layer 55i is a metal layer formed of aluminum or the like, and the outermost layer 55j is unstretched polypropylene ( CPP) is a resin layer formed from a synthetic resin.

  Note that the pack 55 is not limited to such a three-layer structure, and may be one layer or two layers (resin layer + metal layer) used in a known secondary battery element, such as an epoxy resin. A synthetic resin pack or the like can be used.

  And the lead 40a and the lead 45a of the laminated structure 50 protrude outside from the pack 55 through the seal portion 55b, as shown in FIGS.

  In the leads 40a and 45b, the portion sandwiched between the seal portions 55b of the pack 55 is covered with an insulator 14 such as a resin in order to improve the sealing performance as shown in FIGS. Although the material of the insulator 14 is not specifically limited, For example, it is preferable that each is formed from a synthetic resin.

(Pressure sensor)
The pressure sensor 60 has a plate shape and is stacked on the lithium ion secondary battery 5. Specifically, the pressure sensor 60 is stacked on the pack 55 of the lithium ion secondary battery 5 and faces the stacked structure 50 in the stacking direction of the stacked structure 50.

  The pressure sensor 60 is a so-called piezoelectric element in which a piezoelectric plate 63 made of a piezoelectric material is sandwiched between a pair of plate-like electrode plates 61, for example. Examples of the piezoelectric material include PZT. The stacking direction of the electrode plate 61, the piezoelectric plate 63 and the electrode plate 61 of the pressure sensor 60 is the same as the stacking direction of the stacked structure 50 of the lithium ion secondary battery 5. The output terminal 65 a is electrically connected to one electrode plate 61, and the output terminal 65 b is electrically connected to the other electrode plate 61.

  And this pressure sensor 60 detects the pressure (stress) added to the thickness direction (lamination direction), and produces an electromotive force between 65a, 65b between output terminals based on the magnitude | size.

(Spacer)
The spacer 70 has a plate shape and is stacked under the lithium ion secondary battery 5. Specifically, the spacer 70 is overlapped between the pack 55 of the lithium ion secondary battery 5 and the lower plate 90 b of the case 90. The spacer 70 is disposed so as to face the stacked structure 50 in the stacking direction of the stacked structure 50.

  In the present embodiment, the spacer 70 and the pressure sensor 60 are disposed on the opposite sides with the lithium ion secondary battery 5 interposed therebetween, but the spacer 70 is disposed between the pressure sensor 60 and the lithium ion secondary battery 5. These may be provided between the pressure sensor 60 and the upper plate 90a of the case 90, or may have a plurality of spacers 70 and be arranged at a plurality of locations described above.

  The spacer 70 is a member that adjusts the pressure sensor 60 and the lithium ion secondary battery 5 so as to be sandwiched between the upper plate 90a and the lower plate 90b of the case 90 without a gap.

  The material of the spacer 70 is not particularly limited, and a resin material such as polypropylene or a metal material such as stainless steel or aluminum can be used. In particular, in order to detect the expansion and contraction of the lithium ion secondary battery 5 with high accuracy, it is preferable to use a hard material, and a metal material or a hard resin is preferable.

(Case)
The case 90 is a box-shaped container whose one side surface is open, and includes an upper plate 90a, a lower plate 90b opposed to the upper plate 90a, and an upper plate 90a to maintain a distance between the upper plate 90a and the lower plate 90b. It has three side plates 90c that connect the lower plate 90b.

  Between the upper plate 90a and the lower plate 90b, the pressure sensor 60, the lithium ion secondary battery 5, and the spacer 70 are stored in close contact with each other, and the upper plate 90a and the lower plate 90b are accommodated. The pressure sensor 60, the lithium ion secondary battery 5, and the spacer 70 are sandwiched from both sides in the direction in which they are stacked (the vertical direction in the figure).

  The material of the case 90 is not particularly limited, but a resin material such as polypropylene or a metal material such as stainless steel or aluminum can be used. In particular, in order to detect the volume expansion of the lithium ion secondary battery 5 with high accuracy, it is preferable to use a hard material, and a metal material or a hard resin is preferable.

(Production method)
Next, an example of a method for manufacturing the power source 1 will be briefly described with reference to FIGS.

  First, the lithium ion secondary battery 5 is created. First, as shown in FIG. 3, the cathode layer 10 is formed on one surface of the positive electrode current collector 40 having the leads 40 a to obtain a two-layer laminate 120. The cathode layer 10 can be formed by coating the positive electrode current collector 40 with a solvent having the above-described positive electrode active material, conductive additive, binder, and the like.

  In addition, the anode layer 20 is formed on both surfaces of the negative electrode current collector 45 having the leads 45a to obtain a three-layer laminate 140. The anode layer 20 can be formed by applying a solvent having the above-described negative electrode active material, conductive assistant, binder, etc. to the negative electrode current collector 45.

  Subsequently, a separator layer 30 made of an insulating porous material is prepared. And it laminate | stacks like 2 layer laminated body 120 / separator layer 30/3 layer laminated body 140 / separator layer 30/2 layer laminated body 120, and it heats on both sides of the in-plane center part of both sides of these lamination directions Thus, the laminated structure 50 as shown in FIG. 1 is obtained.

  Next, the rectangular sheet 55s obtained by laminating the aluminum foil with the heat-adhesive resin layer is folded and overlapped, and as shown in FIG. The bag-shaped pack 55 in which the opening part 55c for introducing the laminated structure 50 is formed is obtained by heat sealing.

  Then, the laminated structure 50 is inserted into the pack 55 having the opening 55c, and an electrolyte solution is injected into the pack 55 while reducing the pressure inside the pack 55 in the vacuum container, thereby forming the laminated structure 50. Immerse in the electrolyte solution. Thereafter, a part of each of the lead 40a and the lead 45a is protruded from the inside of the pack 55 to the outside, and the opening 55c of the pack 55 is sealed using a heat sealing machine. Thereby, the production of the lithium ion secondary battery 5 as shown in FIG. 1 is completed.

  Subsequently, as shown in FIG. 4B, a spacer 70 having a predetermined thickness and a pressure sensor 60 having a predetermined thickness are prepared, and the distance between the upper plate 90a and the lower plate 90b is set to a predetermined height. 90 is prepared. Here, the total thickness of the spacer 70, the pressure sensor 60, and the lithium ion secondary battery 5 is substantially the same as or less than the distance between the upper plate 90 a and the lower plate 90 b of the case 90.

  And the laminated body L of the spacer 70, the lithium ion secondary battery 5, and the pressure sensor 60 is piled up, inserted between the upper plate 90a and the lower plate 90b of the case 90, and sandwiched. Thereby, the power supply 1 of this embodiment as shown in FIG. 1 is completed.

  According to the power source 1 of the present embodiment, when the lithium ion secondary battery 5 is charged, lithium ions intercalate into the negative electrode active material and the negative electrode active material expands, while lithium ions are deintercalated from the positive electrode active material. The positive electrode active material shrinks. Further, during discharge, lithium ions are deintercalated from the negative electrode active material and the negative electrode active material contracts, while lithium ions are intercalated into the positive electrode active material and the positive electrode active material expands. Since the positive electrode active material and the negative electrode active material have different materials and structures, the degree of expansion / contraction associated with intercalation and deintercalation differs between the positive electrode active material and the negative electrode active material. Accordingly, the expansion / contraction of the positive electrode active material and the expansion / contraction of the negative electrode active material are not completely eliminated during discharging and charging, and the lithium ion secondary battery depends on the degree of charging, that is, the remaining capacity of the battery. The volume of 5 will expand and contract.

  In the power source 1, the lithium ion secondary battery 5 and the pressure sensor 60 are sandwiched by the case 90 from both sides in the direction in which the lithium ion secondary battery 5 and the pressure sensor 60 overlap. Therefore, when the lithium ion secondary battery 5 expands and contracts, the force applied to the pressure sensor 60 changes correspondingly, and the change in the volume of the lithium ion secondary battery 5 is detected as the output value of the pressure sensor 60. Can do. Then, the remaining capacity of the lithium ion secondary battery 5 can be estimated based on the output value of the pressure sensor 60.

  In particular, in the present embodiment, a metal containing Si such as Si or SiLi is used as the negative electrode active material. Then, the lithium ion intercalates into the negative electrode active material of the anode layer 20 at the time of charging, so that the negative electrode active material expands greatly, while the lithium ion deintercalates from the negative electrode active material at the time of discharge. Contracts greatly.

  Therefore, the expansion / contraction change of the lithium ion secondary battery 5 according to the remaining capacity of the battery becomes remarkable. Thereby, the remaining capacity of the battery can be detected with extremely high accuracy.

  The lithium ion secondary battery 5 has a laminated structure 50 in which a cathode layer 10 containing a positive electrode active material, a separator layer 30 and an anode layer 20 containing a negative electrode active material are laminated in this order. It arrange | positions with respect to the structure 50 so that it may oppose in the lamination direction.

  Thereby, the expansion and contraction in the thickness direction of the lithium ion secondary battery 5 caused by the expansion and contraction in the thickness direction of the cathode layer 10 including the positive electrode active material and the anode layer 20 including the negative electrode active material can be easily detected by the pressure sensor 60. The remaining capacity can be acquired with higher accuracy.

  Further, a spacer is provided between at least one of the pressure sensor 60 and the case 90, between the pressure sensor 60 and the lithium ion secondary battery 5, and between the lithium ion secondary battery 5 and the case 90. Since 70 is interposed, it becomes easy to sandwich the lithium ion secondary battery 5 and the pressure sensor 60 between the upper plate 90a and the lower plate 90b of the case 90 without a gap. Therefore, the power source 1 that can acquire the remaining capacity with high accuracy can be easily manufactured.

  Further, since the lithium ion secondary battery 5 further includes a pack 55 that seals the electrolyte solution containing lithium ions, the positive electrode active material, and the negative electrode active material, the electrolyte solution is unlikely to leak from the lithium ion secondary battery 5. Thus, the life of the pressure sensor 60 is improved.

  In addition, in the conventional power source, when a large number of power sources are connected in series and used as a combined power source, it is difficult to grasp the remaining capacity of the lithium ion secondary battery of each power source. When such power supplies 1 are connected in series, the remaining capacity of each power supply 1 can be easily grasped by the output from each pressure sensor 60.

  In addition, this invention is not limited to the said embodiment, It can take various deformation | transformation aspects.

  For example, in the above embodiment, a piezoelectric element that generates an electromotive force according to pressure is used as the pressure sensor 60, but another pressure sensor such as a strain gauge whose resistance value changes according to pressure may be used. Absent.

  Moreover, in the said embodiment, although the case 90 which accommodates the pressure sensor 60, the lithium ion secondary battery 5, and the spacer 70 is used as a clamping member, these pressure sensors 60 and the lithium ion secondary battery 5 are used. The shape is not limited as long as it can be sandwiched from both sides in the overlapping direction.

  In the above embodiment, the spacer 70 is sandwiched between the upper plate 90 a and the lower plate 90 b of the case 90 in addition to the pressure sensor 60 and the lithium ion secondary battery 5. If the lithium ion secondary battery 5 is sandwiched without any gap, the operation is possible even without the spacer 70.

  In the above embodiment, both the positive electrode active material and the negative electrode active material can intercalate and deintercalate lithium ions, but one of the positive electrode active material and the negative electrode active material can intercalate lithium ions. And deintercalation may be possible.

  Moreover, in the said embodiment, although the laminated structure 50 had two secondary battery elements 35 as a single cell, it may have more than two secondary battery elements, One may be sufficient.

  Further, in the above embodiment, the case 90 sandwiches one lithium ion secondary battery, but two or more lithium ion secondary batteries 5 may be stacked and sandwiched.

  Hereinafter, the present invention will be described in more detail with reference to examples of the power source according to the present embodiment, but the present invention is not limited to these examples.

First, a cathode laminate was produced by the following procedure. First, LiCoO ₂ as a positive electrode active material, carbon black and graphite as a conductive aid, polyvinylidene fluoride as a binder (PVdF; PVdF homopolymer particles Kynar 741, weight average molecular weight Mw 5.5 × 10 ⁵ , average particle diameter, manufactured by Atofina) 0.2 μm, soluble in NMP), and after mixing and dispersing with a planetary mixer such that the weight ratio thereof is positive electrode active material: carbon black: graphite: binder = 90: 3: 3: 4 To this, NMP as a solvent was mixed at room temperature so that the weight ratio of NMP: binder was 94: 6 to prepare a slurry cathode coating solution (slurry). Subsequently, an aluminum foil (thickness 60 μm) was prepared, and a cathode coating solution was applied to the aluminum foil by a doctor blade method and dried to obtain a cathode laminate.

  Subsequently, an anode laminate was produced by the following procedure. First, silicon powder is used as the negative electrode active material, carbon black and graphite are used as the conductive additive, and the same PVdF is used as the binder as the cathode, and the weight ratio thereof is negative electrode active material: carbon black: graphite: binding. Agent = 75: 3: 12: 10 After mixing and dispersing with a planetary mixer, NMP as a solvent is added to this at room temperature so that the weight ratio of NMP: binder is 93: 7. A slurry-like coating solution for anode was prepared by mixing below. Next, a copper foil (thickness: 10 μm) as a current collector was prepared, and an anode coating solution was applied to both sides of the copper foil by a doctor blade method and dried to obtain an anode laminate.

  Next, a polyolefin porous film was prepared as a separator and laminated as a cathode laminate / separator / anode laminate / separator / cathode laminate to form a laminated structure, which was fixed by thermocompression bonding from both end faces. Here, lamination was performed such that a cathode laminate having a cathode supported on one side was disposed on the outermost layer of the laminate structure.

Next, LiPF ₆ was dissolved in a solvent in which ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed so as to have a concentration of 1 mol / dm ³ to obtain a nonaqueous electrolyte solution.

  Next, a pack in which an aluminum laminate film was formed in a bag shape was prepared, a laminated structure was inserted, and a nonaqueous electrolyte solution was injected in a vacuum chamber to impregnate the laminated structure in the nonaqueous electrolyte solution. Thereafter, in the reduced pressure state, the entrance of the pack was sealed such that a part of the lead protruded from the outer package, and initial charge / discharge was performed to obtain a stacked lithium ion secondary battery.

  When the charge / discharge cycle is repeated for such a lithium ion secondary battery, the thickness of the lithium ion secondary battery expands greatly when discharged and contracts greatly when discharged as shown by line A in FIG. It was confirmed. In addition, a lithium ion secondary battery using graphite as a negative electrode active material was also produced. However, even in this case, as shown by a line B in FIG.

  Subsequently, a piezoelectric element using PZT as a pressure sensor, a stainless steel spacer having a predetermined thickness, and a squeezed aluminum box-shaped case having a predetermined opening width are prepared, and the piezoelectric element, the lithium ion secondary battery, Spacers were stacked in this order and inserted into the case to complete the power supply. The thickness of the spacer was set so that there was no gap in the thickness direction in the case.

  And the result of having measured the relationship between the charge condition (remaining capacity) of a lithium ion secondary battery and the voltage between terminals of a piezoelectric element is shown in FIG. Depending on the state of charge, the voltage between the terminals of the piezoelectric element changes linearly, indicating that the state of charge can be detected by the pressure sensor 60.

It is a schematic sectional drawing of the power supply which concerns on this embodiment. It is a partially broken top view of the power supply of FIG. It is sectional drawing explaining the method of manufacturing the lithium ion secondary battery of FIG. It is a perspective view following FIG. 3 explaining the method of producing the lithium ion secondary battery of FIG. It is a graph which shows the change of the thickness accompanying charging / discharging of the lithium ion secondary battery which concerns on an Example. It is a graph which shows the change of the output voltage accompanying charging / discharging in the power supply which concerns on an Example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Power source, 5 ... Lithium ion secondary battery, 10 ... Cathode layer (positive electrode layer), 20 ... Anode layer (negative electrode layer), 30 ... Separator layer, 50 ... Laminated structure, 55 ... Pack (battery container), 60 ... pressure sensor, 70 ... spacer, 90 ... case (clamping member).

Claims (4)

A laminated structure in which a positive electrode layer containing a positive electrode active material, a separator layer, and a negative electrode layer containing a negative electrode active material are laminated in this order; an electrolyte; and a flexible container that seals the laminated structure and the electrolyte. A lithium ion secondary battery;
It is overlaid on the outer side of the container of the lithium ion secondary battery so as to face the laminated structure in the lamination direction of the laminated structure, and opposed to the laminated structure in the lamination direction of the laminated structure. A pressure sensor having a surface area equal to or greater than the surface area of the positive electrode layer or the negative electrode layer facing the surface ;
A sandwiching member that sandwiches the lithium ion secondary battery and the pressure sensor from both sides in a direction in which the lithium ion secondary battery and the pressure sensor overlap, and
The lithium ion secondary battery includes an electrolyte containing lithium ions, a positive electrode active material, and a negative electrode active material, and at least one of the positive electrode active material and the negative electrode active material intercalates and deintercalates the lithium ions. Power supply that is possible. A spacer between at least one of the pressure sensor and the clamping member, between the pressure sensor and the lithium ion secondary battery, and between the lithium ion secondary battery and the clamping member. The power supply according to claim 1 , wherein The pressure sensor power supply according to claim 1 or 2 which is a piezoelectric element or a strain gauge. In the lithium ion secondary battery, the negative active material is a lithium-ion can intercalating and deintercalating, the negative active material supply according to any one of claims 1 to 3 containing Si.

Images