JP5211447B2 - All-solid lithium secondary battery and manufacturing method thereof - Google Patents

Description

  The present invention relates to an all solid lithium secondary battery using a lithium ion conductive solid electrolyte and a method for producing the same.

With downsizing of electronic devices, a battery having high energy density is demanded as its main power source or backup power source. In particular, lithium ion secondary batteries are attracting attention because they have higher voltage and higher energy density than conventional batteries using an aqueous solution as an electrolyte. Lithium ion secondary batteries include positive electrode active materials such as LiCoO ₂ , LiMn ₂ O ₄ and LiNiO ₂ , oxides such as carbon and Si as negative electrode active materials, Li _4/3 Ti _5/3 O _{4 and the} like. A solution in which a lithium salt is dissolved in an organic solvent such as carbonate or ether is used as an oxide or electrolyte. However, combustible materials classified as the fourth class of hazardous materials are used for the electrolyte. In addition, there is a concern that the safety may be reduced due to leakage or the equipment used may be damaged.

  In order to make up for the drawbacks of such lithium ion secondary batteries, research on all-solid lithium secondary batteries using a solid electrolyte instead of the electrolyte has been conducted. The all-solid lithium secondary battery has a laminated body in which a solid electrolyte is disposed between positive and negative electrodes as a power generation element. External current collectors are arranged at both ends of the laminate so as to sandwich the side surfaces of the laminate. In this battery, since the electrolyte is not liquid, it is possible to avoid problems such as the above-described leakage. Therefore, it can be mounted directly on the wiring board, and the equipment used can be greatly reduced in size.

However, the current density of an all-solid lithium secondary battery is smaller than that of a lithium secondary battery using a non-aqueous solvent. In order to overcome this, a method has been proposed in which a solid electrolyte is sandwiched between a positive electrode and a negative electrode and stacked to increase the electrode area (for example, Patent Document 1). According to this method, not only the capacity and current density are improved, but also the mounting on a substrate or the like is facilitated because the battery shape is substantially a rectangular parallelepiped.
Japanese Patent Laid-Open No. 06-231796

  However, the above-described external current collector is formed by applying a paste made of a conductive powder and a thickener to the side of the laminated body where the end face of each electrode is exposed. For example, copper powder is used as the conductive powder, and glass frit is used as the thickener, for example. Therefore, the external current collector has a rounded shape. Since the external current collector is formed in this manner, the external current collector tends to be thin at the corners and ridges when the shape of the laminate is a substantially perfect rectangular parallelepiped. In extreme cases, the corners and ridges of the battery may be exposed. When the laminate is exposed from the external current collector, solder wettability of the external current collector during mounting on the board is reduced, resulting in mounting failure. In addition, since the corners and ridges are vulnerable to external stress, when the battery or the substrate is dropped or the substrate is warped in the solder reflow process, the structure of the stacked body becomes brittle.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a highly reliable all-solid lithium secondary battery in which breakdown due to poor substrate mounting or external stress is suppressed.

  In order to solve the above problems, the all solid lithium secondary battery of the present invention has a substantially rectangular parallelepiped laminate composed of a positive electrode, a negative electrode, and a solid electrolyte, and sandwiches the side surfaces of the laminate. Further, an R current chamfered shape or a chamfered shape is provided at the corners and ridges of the laminated body while disposing external current collectors at both ends.

  As described above, according to the present invention, by providing an R chamfered shape or a chamfered shape at a location where an external current collector can be applied in the laminate, there is no portion where the laminate is exposed. Therefore, it is possible to eliminate substrate mounting defects due to a decrease in solder wettability. Moreover, since the laminate itself has a shape without an edge, resistance to external stress is increased. As described above, in an all-solid lithium secondary battery having a substantially rectangular parallelepiped shape that is excellent in mountability, it is possible to eliminate problems such as board mounting defects and breakdown due to external stress, and thus provide a highly reliable all-solid lithium secondary battery. Can do.

  A first invention according to the present invention has a substantially rectangular parallelepiped laminate composed of a positive electrode, a negative electrode and a solid electrolyte, and an external current collector is disposed at both ends so as to sandwich the side surface of the laminate. On the other hand, it is an all-solid lithium secondary battery in which an R chamfered shape or a chamfered shape is provided at the corner and the ridge of the laminate. Thus, by providing an R chamfered shape or a chamfered shape at a location where an external current collector can be applied in the laminate, there are no locations where the laminate is exposed. Therefore, it is possible to eliminate substrate mounting defects due to a decrease in solder wettability. Moreover, since the laminate itself has a shape without an edge, resistance to external stress is increased.

  According to a second aspect of the present invention, in the first aspect, the positive electrode is composed of a positive electrode current collector and a positive electrode active material provided thereon, and the negative electrode is a negative electrode current collector and a negative electrode provided thereon It is an all-solid lithium secondary battery composed of an active material. It is preferable to have a current collector layer that can be a core material for both the positive and negative electrodes, since the current collecting property is improved and the mechanical strength is improved.

  A third invention according to the present invention is an all solid lithium secondary battery according to the second invention, wherein the laminate is formed by laminating a plurality of basic units composed of a positive electrode, a negative electrode, and a solid electrolyte. This configuration is preferable because a decrease in current density, which is a basic problem of an all-solid lithium secondary battery, can be reduced.

  A fourth invention according to the present invention is the all-solid lithium secondary battery according to the third invention, wherein a layer of the same material as the solid electrolyte is provided on the outermost layer of the laminate. It is preferable that the portion to be provided with the R chamfered shape or the chamfered shape is formed of the same material as that of the solid electrolyte because processing reliability is increased.

  A fifth invention according to the present invention is an all-solid lithium secondary battery according to the first invention, wherein the radius of curvature of the R chamfered shape is less than 1/5 of the length of the laminate in the stacking direction and is 30 μm or more. It is. By setting the radius of curvature of the R chamfered shape within this range, it is preferable because the effects of the present invention can be expressed while maintaining high mounting stability.

  A sixth invention according to the present invention is the all-solid lithium secondary battery according to the first invention, wherein the width of the chamfered shape is less than ¼ of the length in the stacking direction of the stacked body and is 45 μm or more. . By setting the width of the chamfered shape within this range, the effect of the present invention can be exhibited while maintaining high mounting stability, which is preferable.

  According to a seventh invention of the present invention, in the first invention, all solid lithium in which a portion exposed from the external current collector of the laminate is sealed with a sealing portion including at least one of glass and a resin mold It is a secondary battery. Thus, it is preferable to provide the sealing portion with a chemically stable material because the storage characteristics of the all-solid lithium secondary battery can be improved.

  According to an eighth aspect of the present invention, there is provided a laminated body having a substantially rectangular parallelepiped shape from a positive electrode, a negative electrode, and a solid electrolyte, and having either a chamfered shape or an R chamfered shape at a corner and a ridge. Is a manufacturing method of an all-solid-state lithium secondary battery, which includes an A step for manufacturing the battery and a B step for arranging an external current collector at both ends of the stacked body so as to sandwich the side surface of the stacked body. Thus, the all solid lithium secondary battery according to the first invention can be manufactured.

  According to a ninth aspect of the present invention, in the eighth aspect, the A step comprises a first step of individually producing a positive electrode active material, a negative electrode active material, and a solid electrolyte green sheet, and a positive electrode active material, a solid electrolyte, and a negative electrode. A second step of sequentially laminating each green sheet in the order of the active material to produce a laminated sheet, a third step of cutting the laminated sheet to obtain a green chip, and corners and ridges of the green chip It is a manufacturing method of the all-solid-state lithium secondary battery including the 4th step which performs either chamfering processing or R chamfering processing, and the 5th step which sinters the green chip after processing. Providing an R chamfered shape or a chamfered shape before sintering the green chip is preferable because the bending strength is further increased and resistance to external stress is improved.

  According to a tenth aspect of the present invention, after the third step of the ninth aspect, the green chip is dried so that the residual amount of plasticizer in the green chip is 25 wt% or more and 99 wt% before the treatment. This is a method for manufacturing a secondary battery. It is preferable to make the remaining amount of the plasticizer within this range because it becomes possible to produce an all-solid lithium secondary battery with a high yield.

  An eleventh invention according to the present invention is a method for manufacturing an all-solid lithium secondary battery in which the corners and ridges of the green chip are polished in the fourth step of the ninth invention. This is preferable because mass productivity increases.

  A twelfth aspect of the present invention is a method for manufacturing an all-solid lithium secondary battery using, in the fourth step of the eleventh aspect, a powder of the same material as the solid electrolyte as an abrasive. In this case, even if the abrasive is mixed in the all-solid lithium secondary battery, it is preferable because no short circuit or deterioration of characteristics occurs.

  According to a thirteenth aspect of the present invention, in the first step of the ninth aspect, a positive electrode active material, a negative electrode active material, and a solid electrolyte green sheet are individually produced on a plurality of releasable base materials, This is a method for producing an all-solid lithium secondary battery in which each green sheet is released from each of a plurality of base materials. Thus, it is preferable to individually produce each green sheet on the moldable base material because each green sheet is easily peeled off from the base material and the yield is improved.

  According to a fourteenth aspect of the present invention, in the eighth aspect, the first step is for the A step to individually produce a positive electrode active material, a positive electrode current collector, a negative electrode active material, a negative electrode current collector, and a solid electrolyte green sheet. And a second step of sequentially laminating each green sheet in the order of a positive electrode current collector, a positive electrode active material, a solid electrolyte, a negative electrode active material, and a negative electrode current collector, and cutting the laminated sheet A third step of obtaining a green chip, a fourth step of performing either chamfering or R-chamfering on the corner and ridge of the green chip, and a fifth step of sintering the green chip after the fourth step And an all-solid lithium secondary battery manufacturing method. As a result, the all-solid-state lithium secondary battery of the second invention is obtained, and by providing an R chamfered shape or a chamfered shape before the green chip is sintered, the bending strength is further increased and resistance to external stress is increased. It is preferable because it improves.

  According to a fifteenth aspect of the present invention, after the third step of the fourteenth aspect, the green chip is dried so that the remaining amount of the plasticizer in the green chip is 25% by weight or more and 99% by weight before processing. It is a manufacturing method of a lithium secondary battery. It is preferable to make the remaining amount of the plasticizer within this range because it becomes possible to produce an all-solid lithium secondary battery with a high yield.

  According to a sixteenth aspect of the present invention, there is provided an all-solid lithium secondary battery manufacturing method in which the corners and ridges of the green chip are polished in the fourth step of the fourteenth aspect. This is preferable because mass productivity increases.

  A seventeenth aspect of the present invention is a method for manufacturing an all-solid lithium secondary battery using, in the fourth step of the sixteenth aspect, a powder of the same material as the solid electrolyte as an abrasive. In this case, even if the abrasive is mixed in the all-solid lithium secondary battery, it is preferable because no short circuit or deterioration of characteristics occurs.

  According to an eighteenth aspect of the present invention, in the second step of the fourteenth aspect, a solid electrolyte, a negative electrode active material, a negative electrode current collector, a negative electrode active material, a solid electrolyte, a positive electrode active material, a positive electrode current collector, and a positive electrode active material This is a method for manufacturing an all-solid lithium secondary battery in which a lamination sheet is produced by performing a lamination operation of sequentially laminating each green sheet a plurality of times. This is preferable because the all-solid lithium secondary battery of the third invention can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited to the following embodiment.

(Embodiment 1)
FIG. 1 is a cross-sectional view of an all solid lithium secondary battery according to Embodiment 1 of the present invention. The laminated body 21 includes a positive electrode 2 including a positive electrode active material, a negative electrode 3 including a negative electrode active material, and a solid electrolyte 1 interposed between the positive electrode 2 and the negative electrode 3. The external current collectors 6 </ b> A and 6 </ b> C are arranged at both ends of the stacked body 21 so as to sandwich the side surface of the stacked body 21. The external current collectors 6A and 6C are connected to the negative electrode 3 and the positive electrode 2, respectively.

A compound having a composition represented by LiMPO ₄ (M is at least one selected from Mn, Fe, Co, and Ni) is generally used for the positive electrode active material constituting the positive electrode 2. In addition, LiCoO ₂ , LiNiO ₂ or a modified product thereof can be used. The negative electrode active material constituting the negative electrode ₃ may be at least one selected from FePO ₄ , Li ₃ Fe ₂ (PO ₄ ) ₃ , and LiFeP ₂ O ₇ .

The solid electrolyte 1 includes Li _{1 + X} M ^III _X Ti ^IV _2-X (PO ₄ ) ₃ (M ^III is at least one trivalent metal ion selected from Al, Y, Ga, In, and La, 0 ≦ X ≦ 0. .6) is generally used. In addition, a lithium ion conductor made of a main element of Li _0.33 La _0.56 TiO ₃ can be used as a sintered solid electrolyte. Li _{1 + X} M ^III _X Ti ^IV _2-X (PO ₄ ) ₃ also serves as a negative electrode active material together with a solid electrolyte, and an electrically inactive layer does not form even when fired simultaneously with the positive electrode active material or the negative electrode active material. Therefore, it is preferable.

  The laminated body 21 configured by laminating the above components is formed in a substantially rectangular parallelepiped shape from the viewpoint of emphasizing mountability. Out of the six surfaces of the rectangular parallelepiped, the external current collectors 6A and 6C are arranged on the two surfaces where the end surfaces of the positive electrode 2 and the negative electrode 3 are exposed. The external current collectors 6A and 6C are formed of a conductive powder and a thickener. For example, copper powder is used as the conductive powder, and glass frit is used as the thickener, for example.

  An R chamfered shape 21 </ b> C is provided on the ridge portion 21 </ b> A of the stacked body 21. Although not shown, an R chamfered shape 21 </ b> C is also provided at the corner of the laminate 21. As described above, by providing the R chamfered shape 21C at the location where the external current collectors 6A and 6C are provided in the laminated body 21, the thickness of the external current collectors 6A and 6C is small, and the laminated body 21 that is the battery body is formed. There are no exposed areas. As a result, the occurrence of board mounting defects due to a decrease in solder wettability is suppressed. Moreover, since the laminated body 21 has a shape without an edge, resistance to external stress is increased. In addition, from the viewpoint of strength, an R chamfered shape 21 </ b> C may be provided on a ridge portion parallel to the stacking direction of the stacked body 21.

  Next, the manufacturing method of the all-solid-state lithium secondary battery by this Embodiment is demonstrated using FIGS. 2, 3, and 5 are cross-sectional views for explaining a method for manufacturing an all solid lithium secondary battery according to the present embodiment, and FIG. 4 is a perspective view thereof.

  First, a solid electrolyte green sheet 1G, a positive electrode active material green sheet 2G, and a negative electrode active material green sheet 3G are prepared. A method for producing the positive electrode active material green sheet 2G will be described with reference to FIG. The above-described positive electrode active material, a resin such as cellulose, and a plasticizer are added to an organic solvent such as butyl acetate to prepare a slurry whose viscosity is adjusted. This slurry is applied onto a base material 23 such as a resin film and dried at a low temperature. Finally, the dried green sheet 2G is released from the base material 23. At this time, it is preferable that a release agent layer 23 </ b> A is formed in advance on the surface of the base material 23.

  The green sheet 3G of the negative electrode active material is also produced in the same manner as the green sheet 2G by using the negative electrode active material instead of the positive electrode active material. The solid electrolyte green sheet 1G is also produced in the same manner as the green sheet 2G by using a solid electrolyte instead of the positive electrode active material.

  Next, as shown in FIG. 3, a polyester film 5 with an adhesive is pasted on a support base 4, and a positive electrode active material green sheet 2 </ b> G formed on a base material 23 is placed thereon. And between the base material 23 and the support stand 4 is pressurized, the base material 23 is peeled from the green sheet 2G.

  After a plurality of layers of the solid electrolyte green sheets 1G are laminated thereon in the same manner, finally, the negative electrode active material green sheets 3G are laminated. In this way, a laminated sheet 25 composed of the green sheet 2G / green sheet 1G / green sheet 3G is produced.

  Next, the laminated sheet 25 is cut and the polyester film 5 is peeled off to obtain the green chip 22 shown in FIG. Then, the corner portion 22B and the ridge portion 22A of the green chip 22 are polished to form an R chamfered shape 22C as shown in FIG. Thereafter, the substrate is washed and dried, and then the binder is removed in a baking furnace. Thereafter, the temperature is further raised to sinter the green chip 22 and then quickly cooled to room temperature. In this way, the laminate 21 is obtained.

  Finally, a paste composed of conductive powder and a thickener is applied to both ends of the laminate 21 so as to sandwich the side surfaces of the laminate 21, and baked. In this way, the external current collectors 6A and 6C are formed as shown in FIG. Thus, the all solid lithium secondary battery according to the present embodiment is completed.

  Furthermore, as shown in FIG. 6, it is preferable to seal the part exposed from the external collectors 6A and 6C of the laminate 21 with a sealing part 12 made of at least one of glass or resin. By blocking the laminated body 21, particularly the solid electrolyte 1, from the outside air, it is possible to minimize the deterioration of the battery material.

  In addition, after producing the green chip 22, it is preferable to dry the green chip 22 and reduce the residual amount of plasticizer before forming the R chamfered shape 22C at the corner 22B and the ridge 22A. At this time, the remaining amount of the plasticizer in the green chip 22 is more preferably 25 wt% or more and 99 wt% or less. Here, the residual amount of the plasticizer can be determined by either gas chromatography or mass spectrum.

  When the remaining amount is excessively large, the green chip 22 is viscous, so that the green sheets adhere to each other during the forming process of the R chamfered shape 21 </ b> C, thereby increasing the possibility of causing a short circuit failure. On the other hand, when the remaining amount is excessively small, the brittleness of the green chip 22 is increased, so that the green chip 22 is likely to be cracked or peeled when the R chamfered shape 21C is formed. By making the residual amount of the plasticizer within the above range, it becomes possible to produce an all-solid lithium secondary battery with good yield.

  In addition, when forming the R chamfered shape 22C at the corner 22B and the ridge 22A, it is preferable to polish the corner 22B and the ridge 22A using an abrasive. In this case, a material having a small influence on battery characteristics such as alumina is used for the abrasive. This increases mass productivity. Furthermore, it is preferable to use a powder of the same material as the solid electrolyte 1 as an abrasive. Even if a powder of the same material as the solid electrolyte 1 as an abrasive is mixed, no short circuit or characteristic deterioration occurs.

  The radius of curvature of the R chamfered shape 21 </ b> C is preferably less than 1/5 of the length of the stacked body 21 in the stacking direction, and is preferably 30 μm or more. If the radius of curvature is excessively large, the mounting stability that is a feature of the rectangular parallelepiped is impaired. On the other hand, if the radius of curvature is excessively small, the coating thickness of the external current collectors 6A and 6C becomes small, and the effect of the present invention becomes small. By setting the radius of curvature of the R chamfered shape 21 </ b> C within the above range, the effects of the present invention can be exhibited while maintaining high mounting stability.

  As shown in FIG. 7, a chamfered shape 21 </ b> D may be formed instead of forming the R chamfered shape 22 </ b> C at the corners and ridges 21 </ b> A of the stacked body 21. The chamfered shape 21D can also be formed by polishing similarly to the R chamfered shape 22C. In this case, the width 21E of the chamfered shape 21D is preferably less than ¼ of the length of the stacked body 21 in the stacking direction and 45 μm or more. The reason is the same as the preferable range of the radius of curvature of the R chamfered shape 21C.

Next, effects of the present embodiment will be described using specific examples. Solid electrolyte powder having a composition represented by Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ , positive electrode active material powder represented by LiCoPO ₄ , and Li ₃ Fe ₂ (PO ₄ ) A negative electrode active material powder represented by ₃ was prepared. Then, polyvinyl butyral resin as a binder, nbutyl acetate as a solvent, and dibutyl phthalate as a plasticizer were added to each powder. Each of these mixtures was mixed with a zirconia ball in a ball mill for 24 hours to prepare a slurry composed of a solid electrolyte, a positive electrode active material, and a negative electrode active material, respectively.

  Next, as shown in FIG. 2, a positive electrode active material slurry was applied and dried on a base material 23 containing a polyester resin as a main component by using a doctor blade to produce a green sheet 2G of a positive electrode active material having a thickness of 3 μm. A release agent layer 23A containing Si as a main component was formed on the surface of the base material 23 in advance. Using a similar method, a solid electrolyte green sheet 1G having a thickness of 25 μm and a negative electrode active material green sheet 3G having a thickness of 5 μm were prepared.

Next, as shown in FIG. 3, a polyester film 5 with an adhesive is stuck on a support base 4, and a green sheet 2G formed on a base material 23 is placed on the polyester film 5, and 80 kg / kg in a 70 ° C. environment. After applying a pressure of cm ^2, the base material 23 was peeled from the green sheet 2G. After a total of 40 layers of the solid electrolyte green sheet 1G were laminated thereon in the same manner, the negative electrode active material green sheet 3G was finally laminated, and from the green sheet 2G / green sheet 1G / green sheet 3G having a thickness of about 1 mm. A laminated sheet 25 was produced.

  Next, as shown in FIG. 4, the lamination sheet 25 was cut | disconnected and the green film 22 was obtained by peeling the polyester film 5 with the adhesive agent. The dimensions of the green chip 22 were 1.0 mm in length, 1.0 mm in width, and 1.0 mm in height.

  Next, the green chip 22 was dried at 170 ° C. for 30 minutes, so that the remaining amount of the plasticizer was 25% by weight. After that, as shown in FIG. 5, alumina was used as an abrasive, and the corner 22B and the ridge 22A were polished by an end face polishing apparatus to form an R chamfered shape 22C having a curvature radius of about 30 μm. After washing and drying, the binder was removed in a baking furnace at 400 ° C. for 5 hours and sintered at a maximum temperature of 950 ° C., and then quickly cooled to room temperature.

  And as shown in FIG. 1, after apply | coating the paste which consists of gold | metal | money and glass frit on the surface of the positive electrode 2 and the negative electrode 3 of the laminated body 21 obtained by sintering the green chip | tip 22, it is 600 degreeC environment. External current collectors 6A and 6C were formed by heat treatment for 1 hour.

The dimensions of the laminated body 21 were 0.9 mm in length, 0.9 mm in width, and 0.9 mm in height without considering the R chamfered shape 21C, and the dimensions of the R chamfered shape 21C were not changed before and after sintering. Moreover, the filling density of the laminated body 21 when it was assumed that all the laminated bodies 21 were Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ was about 85%. When the polished cross section of the laminate 21 was observed with an SEM image, the thicknesses of the positive electrode 2 and the negative electrode 3 were about 1 μm and about 2 μm, respectively. Thus, an all-solid lithium secondary battery of Sample A was obtained.

  Next, a manufacturing procedure of the all-solid lithium secondary battery of Sample B will be described. The green chip 22 shown in FIG. 4 was produced in the same manner as the sample A, dried, and then the corner 22B and the ridge 22A were polished with an end face polishing apparatus using alumina as the polishing agent in FIG. As shown, a chamfered shape 22D having a chamfer width 22E of 45 μm was formed. Thereafter, in the same manner as Sample A, an all-solid lithium secondary battery of Sample B was obtained. The dimensions, packing density, thicknesses of the positive electrode 2 and the negative electrode 3 in a state where the chamfering of the laminate 21 of the sample B was not taken into consideration were the same as those of the sample A. Moreover, there was no change in the dimension of the chamfered shape 22D before and after sintering.

  In the production of the all-solid lithium secondary battery of Sample C, an R chamfered shape 21C was formed immediately after the green chip 22 was sintered in the production of Sample A. Except for this, an all-solid lithium secondary battery of Sample C was produced in the same manner as Sample A.

  In the production of the all-solid lithium secondary battery of sample D, the chamfered shape 21D was formed immediately after the green chip 22 was sintered in the production of sample B. Except for this, an all-solid lithium secondary battery of Sample D was produced in the same manner as Sample B.

  In the production of the all-solid lithium secondary batteries of Sample E to Sample H, the curvature radii of the R chamfered shape 22C were formed to 20 μm, 100 μm, 180 μm, and 200 μm, respectively, in the production of Sample A. Except for this, Sample E to Sample H of all solid lithium secondary batteries were produced in the same manner as Sample A.

  In the production of the all-solid lithium secondary batteries of Sample J to Sample M, the chamfered width 22E of the chamfered shape 22D was formed to 20 μm, 100 μm, 180 μm, and 200 μm, respectively, in the production of Sample B. Other than this, the all-solid lithium secondary batteries of Sample J to Sample M were fabricated in the same manner as Sample B.

  In the production of the all-solid lithium secondary batteries of Sample N to Sample R, the radius of curvature of the R chamfered shape 21C was formed to 20 μm, 100 μm, 180 μm, and 200 μm, respectively, in the production of Sample C. Sample N to sample R all-solid lithium secondary batteries were produced in the same manner as sample C, except for this.

  In the production of the all solid lithium secondary batteries of Sample S to Sample V, the chamfered width 21E of the chamfered shape 21D was formed to 20 μm, 100 μm, 180 μm, and 200 μm, respectively, in the production of Sample D. Other than this, the all-solid lithium secondary batteries of Sample S to Sample V were fabricated in the same manner as Sample D.

  In order to compare with these samples, as shown in the cross-sectional view of FIG. 9, a comparative sample A having a laminate in which no processing was performed at corners and ridges was produced.

  The above batteries were subjected to a three-point bending test in accordance with the standard of JIS-R1601, and the bending strength was measured. Moreover, the mounting defect rate was measured. As shown in FIG. 10, in the mounting test, a sample of an all-solid-state lithium secondary battery is connected to a wiring pattern 42 on a glass epoxy substrate 41 (wiring substrate) with solder 43 to external current collectors 6A and 6C. I went. After the connection, it was first heated to 270 ° C., and then the impedance analysis was performed between the wiring patterns 42. And the sample which showed the impedance more than a threshold value by making 1 kohm into a threshold value was determined to be mounting defect. In this way, the mounting defect rate was calculated for 100 samples. The results are shown in (Table 1) and (Table 2).

  As shown in (Table 1) and (Table 2), by providing R chamfered shape 21C and chamfered shape 21D at corners and ridges 21A, all solid lithium secondary of all other samples compared to comparative sample A The bending strength of the battery is high. Further, by providing the R chamfered shape 22C and the chamfered shape 22D before the green chip 22 is sintered, the bending strength is further increased. That is, resistance to external stress is improved. This is considered to be a result of the strength being improved because the structures of the R chamfered shape 22C and the chamfered shape 22D are made more uniform in the firing stage.

  However, in the samples C and E, in which the radius of curvature of the R chamfered shape 21C is 20 μm, and the samples J and S in which the chamfer width 21E is 35 μm, a very high bending strength was not obtained. On the other hand, sufficient bending strength was obtained even with samples H and R having a curvature radius exceeding 1/5 with respect to the thickness (0.9 mm) in the stacking direction of the laminate 21 without considering the R chamfered shape 21C. However, since the flat portion is small, it is difficult to stand still. The same applies to the samples M and V in which the chamfering width 21E exceeds 1/4 with respect to the thickness of the stacked body 21 in the stacking direction not considering the chamfered shape 21D. Since the stationary property is an essential requirement for mounting on the substrate, the radius of curvature is preferably 1/5 or less of the thickness of the laminate 21 in the stacking direction without considering the R chamfered shape 21C. Similarly, the chamfering width 21E is preferably ¼ or less of the thickness of the stacked body 21 in the stacking direction not considering the chamfered shape 21D.

  Moreover, as shown in Table 1 and Table 2, the mounting defect rate of the all-solid lithium secondary battery became zero by providing the R chamfered shape 21C and the chamfered shape 21D at the corners and ridges 21A. On the other hand, in the comparative sample A in which the R chamfered shape 21C and the chamfered shape 21D were not provided at the corners and ridges 21A, 3% mounting failure occurred. This is probably because the external current collector 6A or 6C becomes thin at the corners and ridges, and the battery body is locally exposed, which reduces solder wettability and leads to mounting defects.

  Next, the effect of the sealing part 12 shown in FIG. 6 is demonstrated. In the production of sample W, a paste made of glass frit is further applied to the portion not covered with external current collectors 6A and 6C in the production of sample A, and then fired in the atmosphere at 400 ° C. for 1 hour to seal part 12. Was provided. Thus, an all-solid lithium secondary battery of Sample W was obtained.

  In the production of sample X, a paste made of glass frit is further applied to the portion not covered with the external current collectors 6A and 6C in the production of sample B, followed by firing in the atmosphere at 400 ° C. for 1 hour, thereby sealing portion 12 Was provided. In this way, an all solid lithium secondary battery of Sample X was obtained.

  In the preparation of Sample Y, the sealing portion 12 was provided by applying a water-resistant epoxy resin to the portions not covered with the external current collectors 6A and 6C in the preparation of Sample A. In this way, an all-solid lithium secondary battery of Sample Y was obtained.

  Each of the above batteries was discharged after being stored in a constant temperature and humidity chamber at 60 ° C. and 85% for 30 days in a charged state, and the discharge capacity was measured. The results are shown in (Table 3). In an atmosphere with a dew point of −50 ° C. and 25 ° C., the battery was charged to 2.2 V at a constant current of 10 μA and discharged to 1.0 V.

  Samples A and B that are not provided with the sealing part 12 have a larger discharge capacity after storage and excellent storage characteristics in the samples W and X that are provided with the sealing part 12 made of glass frit. Was confirmed. This effect is also confirmed in the sample Y using an epoxy resin as the material of the sealing portion 12. Thus, by providing the sealing portion 12 with a chemically stable material, the storage characteristics of the all-solid lithium secondary battery according to the present embodiment can be improved.

(Embodiment 2)
FIG. 11 is a cross-sectional view of an all-solid lithium secondary battery according to Embodiment 2 of the present invention. The laminated body 31 is formed by substantially laminating these units with the positive electrode 2 including the positive electrode active material, the negative electrode 3 including the negative electrode active material, and the solid electrolyte 1 interposed between the positive electrode 2 and the negative electrode 3 as one unit. It has a rectangular parallelepiped shape. The plurality of positive electrodes 2 and the plurality of negative electrodes 3 are exposed on the opposing surfaces of the laminate 31, and the external current collectors 6 </ b> A and 6 </ b> C are connected to the negative electrode 3 and the positive electrode 2, respectively. That is, the external current collectors 6 </ b> A and 6 </ b> C are arranged at both ends of the multilayer body 31 so as to sandwich the side surface of the multilayer body 31. Thus, since the laminated body 31 has a plurality of basic units including the positive electrode 2, the negative electrode 3, and the solid electrolyte 1, it is possible to reduce a decrease in current density, which is a basic problem of an all-solid lithium secondary battery.

  The positive electrode 2 preferably has a structure in which the positive electrode current collector layer 2B is sandwiched between the positive electrode active material layers 2A from both sides. Similarly, the negative electrode 3 preferably has a structure in which the negative electrode current collector layer 3B is sandwiched between the negative electrode active material layers 3A from both sides. That is, the positive electrode 2 has a configuration in which the positive electrode active material layer 2A is provided on both surfaces of the positive electrode current collector layer 2B, and the negative electrode 3 has a configuration in which the negative electrode active material layer 3A is provided on both surfaces of the negative electrode current collector layer 3B. Preferably there is. It is preferable that both the positive electrode 2 and the negative electrode 3 have the positive electrode current collector layer 2B and the negative electrode current collector layer 3B that can serve as cores, because the current collecting property is improved and the mechanical strength is improved. This configuration may be applied to the laminate 21 of the first embodiment. That is, you may form a positive electrode collector layer and a negative electrode collector layer in the surface which forms the external collectors 6A and 6C, respectively.

  The positive electrode current collector layer 2 </ b> B and the negative electrode current collector layer 3 </ b> B are preferably materials that do not react with the positive and negative electrode active materials and can be heat-treated in the same atmosphere as the positive and negative electrode active materials and the solid electrolyte 1. By satisfying this requirement, an electrochemically inert interface is not generated. Specifically, platinum, gold, silver, palladium, copper, nickel, cobalt, stainless steel, and the like are applicable. However, since metals such as copper, nickel, cobalt, stainless steel, and silver have high reactivity with the active material, it is essential to control the firing atmosphere in the firing step. Accordingly, platinum, gold and palladium are most preferable. The positive electrode current collector layer 2B and the negative electrode current collector layer 3B are preferably inserted into the central portions of the positive electrode active material layer 2A and the negative electrode active material layer 3A made of positive and negative electrode active materials, respectively.

  An R chamfered shape 31 </ b> C is provided on the ridge 31 </ b> A of the stacked body 31. Although not shown, an R chamfered shape 21 </ b> C is also provided at the corner of the laminate 31. As described above, by providing the R chamfered shape 31C at the location where the external current collectors 6A and 6C are provided in the laminated body 31, the coating thickness of the external current collectors 6A and 6C is small, and the laminated body 21 that is the battery body is formed. There are no exposed areas. As a result, the occurrence of board mounting defects due to a decrease in solder wettability is suppressed. Moreover, since the laminated body 31 becomes a shape without an edge, the tolerance with respect to an external stress becomes high. As in the first embodiment, chamfered shapes may be provided at the ridges 31A and corners of the laminate 31.

  Next, the manufacturing method of the all-solid-state lithium secondary battery by this Embodiment is demonstrated using FIGS. 12 to 15 are plan views showing green sheets of a positive electrode active material, a positive electrode current collector, a negative electrode active material, and a negative electrode current collector, respectively. 16 and 17 are cross-sectional views of the negative electrode laminate green sheet and the positive electrode laminate green sheet, respectively. FIG. 18 is a cross-sectional view of a laminated sheet. FIG. 19A is a plan view of a green chip, and FIGS. 19B, 19C, and 20 are cross-sectional views thereof.

  First, a positive electrode active material slurry similar to that of the first embodiment is screen-printed on the carrier film 7 similar to the base material 23 of the first embodiment so as to form a staggered pattern as shown in FIG. Thereby, the green sheet 2G of a positive electrode active material is produced. On the other hand, as shown in FIG. 13, the current collector paste slurry mainly composed of palladium is screen-printed on the carrier film 7 so as to form a staggered pattern at the same pitch as the positive electrode active material slurry. Thereby, the green sheet 2H of the positive electrode current collector is produced.

  Further, a negative electrode active material slurry similar to that in Embodiment 1 is screen-printed on the carrier film 7 so as to form a staggered pattern as shown in FIG. Thereby, the green sheet 3G of a negative electrode active material is produced. On the other hand, as shown in FIG. 15, the current collector paste slurry mainly composed of palladium is screen-printed on the carrier film 7 so as to form a staggered pattern at the same pitch as the negative electrode active material slurry. Thereby, the green sheet 3H of the negative electrode current collector is produced.

  Although not shown, a solid electrolyte slurry similar to that of the first embodiment is applied and dried on the carrier film 7 to produce a solid electrolyte green sheet 1G.

  Next, as shown in FIGS. 16 and 17, a negative electrode laminate green sheet 10 and a positive electrode laminate green sheet 11 are prepared using these. First, as shown in FIG. 16, the green sheet 3G of the negative electrode active material is placed on the green sheet 1G of the solid electrolyte on the carrier film 7 and pressed. Thereafter, the carrier film 7 in contact with the green sheet 3G is peeled from the green sheet 3G, and the green sheet 3G is provided on the green sheet 1G. In the same manner, a negative electrode current collector green sheet 3H is provided thereon, and further a green sheet 3G is provided thereon. In this way, the negative electrode laminate green sheet 10 is produced.

  On the other hand, as shown in FIG. 17, a green sheet 2G of the positive electrode active material is placed on the solid electrolyte green sheet 1G on the carrier film 7 and pressed. Thereafter, the carrier film 7 in contact with the green sheet 2G is peeled off from the green sheet 2G, and the green sheet 2G is provided on the green sheet 1G. A green sheet 2H as a positive electrode current collector is provided thereon in the same manner, and a green sheet 2G is further provided thereon. In this way, the positive electrode laminate green sheet 11 is produced.

  Next, the laminated sheet 33 shown in FIG. 18 is produced using the negative electrode laminate green sheet 10 and the positive electrode laminate green sheet 11. A polyester film 5 with an adhesive is pasted on the support base 4, and a solid electrolyte green sheet 1G formed on the carrier film 7 is placed thereon. Furthermore, the negative electrode laminate green sheet 10 formed on the carrier film 7 is placed thereon and pressed. Thereafter, the carrier film 7 is peeled from the negative electrode laminate green sheet 10. Further, the positive electrode laminate green sheet 11 formed on the carrier film 7 is placed on the negative electrode laminate green sheet 10 and pressed. Thereafter, the carrier film 7 is peeled from the positive electrode laminate green sheet 11. This operation is repeated a predetermined number of times, and finally the negative electrode laminate green sheet 10 and the green sheet 1G are laminated in this order. In this way, a laminated sheet 33 in which the pattern of green sheet 3H-green sheet 3G-green sheet 1G-green sheet 2G-green sheet 2H is repeated is obtained.

  Next, the laminated sheet 33 is cut at a position between the green sheets 2G parallel to the longitudinal direction of each green sheet 2G, and further cut into individual pieces so that the ends of the green sheets 2G and 3G are exposed. To do. FIG. 19A is a plan view of the green chip 32 in which the polyester film 5 is peeled from the piece cut in this way. FIG. 19B is a schematic view of the XX cross section in FIG. 19A, and FIG. 19C is a schematic view of the YY cross section. As can be seen from FIG. 19B, the cross sections of the green sheets 2G and 2H for the positive electrode and the green sheets 3G and 3H for the negative electrode are respectively exposed at one end face (cut surface).

  Then, the corner 32B and the ridge 32A of the green chip 32 are polished to form an R chamfered shape 32C as shown in FIG. Thereafter, the substrate is washed and dried, and then the binder is removed in a baking furnace. Thereafter, the temperature is further raised to sinter the green chip 32, and then quickly cooled to room temperature. In this way, a laminate 31 shown in FIG. 11 is obtained. In the laminated body 31, the basic unit is solid electrolyte 1-negative electrode 3-solid electrolyte 1-positive electrode 2-solid electrolyte 1-negative electrode 3-solid electrolyte 1.

  Finally, a paste composed of a conductive powder and a thickener is applied to both ends of the laminate 31 so as to sandwich the side surfaces of the laminate 31, and baked. In this way, the external current collectors 6A and 6C are formed. Thus, the all solid lithium secondary battery according to the present embodiment is completed.

  In addition, as shown in FIG. 21, it is preferable to seal the part exposed from the external electrical power collectors 6A and 6C around the laminated body 31 using the sealing part 12 which consists of at least one of glass or resin. Similarly to the first embodiment, it is preferable to dry the green chip 32 and reduce the remaining amount of the plasticizer before forming the R chamfered shape 32C. In addition, when the R chamfered shape 32C is formed, it is preferable that polishing is performed using an abrasive, and it is also preferable that a powder of the same material as the abrasive and the solid electrolyte 1 is used.

  Further, a planar chamfered shape may be provided instead of the R chamfered shape 31C. The preferable ranges of the radius of curvature of the chamfered shape 31C and the chamfered width of the chamfered shape are the same as those in the first embodiment.

  In addition, when forming the lamination sheet 33 as mentioned above, it is preferable to arrange | position the solid electrolyte green sheet 1G in the outermost layer, and to form the layer of the solid electrolyte 1 in the outermost layer of the laminated body 31. FIG. If the R chamfered shape 31C or the portion to which the chamfered shape is imparted is formed of the solid electrolyte 1, the processing reliability is increased.

  Next, effects of the present embodiment will be described using specific examples. First, a positive electrode active material green sheet 2G having a width of 1.5 mm, a length of 6.8 mm, and a thickness of 3 μm was prepared on a carrier film 7 as shown in FIG. On the other hand, a green sheet 2H of a positive electrode current collector having the same size as the green sheet 2G and a thickness of 5 μm was prepared on a carrier film 7 using a current collector paste slurry mainly composed of palladium as shown in FIG. The interval between the green sheets 2G in the longitudinal direction was 0.4 mm, and the interval in the width direction was 0.3 mm.

  On the other hand, as shown in FIG. 14 using a negative electrode active material slurry having the same composition as that of sample A, a green film 3G of negative electrode active material having the same size as green sheet 2G and a thickness of 5 μm is formed at the same pitch as green sheet 2G. 7 was prepared. On the other hand, as shown in FIG. 15, a negative electrode current collector green sheet 3H having the same size as the green sheet 3G and a thickness of 5 μm was prepared on a carrier film 7 using a current collector paste slurry mainly composed of palladium.

  Although not shown, a solid electrolyte slurry having the same composition as Sample A was applied and dried on the carrier film 7 to produce a solid electrolyte green sheet 1G having a thickness of 25 μm.

Next, as shown in FIG. 16, the green sheet 3G of the negative electrode active material was placed on the solid electrolyte green sheet 1G on the carrier film 7, and a pressure of 80 kg / cm ² was applied in a 70 ° C. environment. Thereafter, the carrier film 7 in contact with the green sheet 3G was peeled off from the green sheet 3G, and the green sheet 3G was provided on the green sheet 1G. In the same manner, a green sheet 3H of a negative electrode current collector was provided thereon, and a green sheet 3G was further provided thereon. In this way, a negative electrode laminate green sheet 10 was produced.

On the other hand, as shown in FIG. 17, the green sheet 2G of the positive electrode active material was placed on the solid electrolyte green sheet 1G on the carrier film 7, and a pressure of 80 kg / cm ² was applied in a 70 ° C. environment. Thereafter, the carrier film 7 in contact with the green sheet 2G was peeled from the green sheet 2G, and the green sheet 2G was provided on the green sheet 1G. In the same manner, a green sheet 2H of a positive electrode current collector was provided thereon, and a green sheet 2G was further provided thereon. In this way, a positive electrode laminate green sheet 11 was produced.

Next, as shown in FIG. 18, a polyester film 5 with an adhesive was pasted on the support base 4, and a solid electrolyte green sheet 1G formed on the carrier film 7 was placed thereon. Furthermore, the negative electrode laminate green sheet 10 formed on the carrier film 7 was placed thereon, and a pressure of 80 kg / cm ² was applied in a 70 ° C. environment. Thereafter, the carrier film 7 was peeled from the negative electrode laminate green sheet 10. Further, the positive electrode laminate green sheet 11 formed on the carrier film 7 was placed on the negative electrode laminate green sheet 10, and a pressure of 80 kg / cm ² was applied in an environment of 70 ° C. Thereafter, the carrier film 7 was peeled from the positive electrode laminate green sheet 11. This operation was repeated a predetermined number of times, and finally the negative electrode laminate green sheet 10 and the green sheet 1G were laminated in this order. In this way, a laminated sheet 33 in which the pattern of green sheet 2H-green sheet 2G-green sheet 1G-green sheet 3G-green sheet 3H was repeated was obtained.

  Next, the laminated sheet 33 was cut into pieces. The polyester film 5 was peeled off from the pieces cut in this way to obtain a green chip 32 shown in FIG. Then, the corner portion and the ridge portion 32A of the green chip 32 were polished to form an R chamfered shape 32C as shown in FIG. Thereafter, it was washed and dried, and then the binder was removed in a baking furnace. Thereafter, the temperature was further raised to sinter the green chip 32, and then quickly cooled to room temperature. Thus, the laminated body 31 shown in FIG. 11 was obtained. The laminated body 31 has a width of about 3.2 mm, a depth (length) of about 1.6 mm, and a height of about 0.9 mm.

  Finally, a paste composed of conductive powder and a thickener was applied to both ends of the laminate 31 so as to sandwich the side surfaces of the laminate 31, and baked. In this way, external current collectors 6A and 6C were formed. The drying conditions of the green chip 32, the binder removal and sintering conditions of the laminate 31, and the baking conditions of the external current collectors 6A and 6C are the same as those of the sample A of the first embodiment. In this way, an all-solid lithium secondary battery of Sample AA was obtained.

  Next, a manufacturing procedure of the all-solid lithium secondary battery of sample AB will be described. After the green chip 32 shown in FIG. 19A was produced in the same manner as the sample AA, the corner and the ridge 32A were polished with an end face polishing apparatus using alumina as an abrasive, and a chamfered shape having a width of 45 μm. Formed. Thereafter, an all-solid lithium secondary battery of Sample AB was obtained in the same manner as Sample AA.

  In the production of the all-solid lithium secondary battery of sample AC, an R chamfered shape 21C was formed immediately after the green chip 32 was sintered in the production of sample AA. Except for this, an all solid lithium secondary battery of Sample AC was produced in the same manner as Sample AA.

  In the production of the all-solid lithium secondary battery of sample AD, a chamfered shape was formed immediately after the green chip 32 was sintered in the production of sample AB. Except for this, an all solid lithium secondary battery of Sample AD was produced in the same manner as Sample AB.

  In the production of the all-solid lithium secondary batteries of Sample AE to Sample AH, the radius of curvature of the R chamfered shape 32C was formed to 20 μm, 100 μm, 170 μm, and 200 μm, respectively, in the production of Sample AA. Other than this, the all-solid lithium secondary batteries of Sample AE to Sample AH were fabricated in the same manner as Sample AA.

  In the production of the all solid lithium secondary batteries of Sample AJ to Sample AM, the chamfered widths of the chamfered shapes were formed to 35 μm, 150 μm, 210 μm, and 250 μm, respectively, in the production of Sample AB. Except for this, all solid lithium secondary batteries of Sample AJ to Sample AM were produced in the same manner as Sample AB.

  In the production of the all-solid lithium secondary batteries of Sample AN to Sample AR, the radius of curvature of the R chamfered shape 31C was formed to 20 μm, 100 μm, 170 μm, and 200 μm, respectively, in the production of Sample AC. Except for this, all solid lithium secondary batteries of Sample AN to Sample AR were fabricated in the same manner as Sample AC.

  In the manufacture of the all-solid lithium secondary batteries of Sample AS to Sample AV, the chamfered widths of the chamfered shapes were formed to 35 μm, 150 μm, 210 μm, and 250 μm, respectively, in the manufacture of Sample AD. Except for this, sample AS to sample AV all solid lithium secondary batteries were fabricated in the same manner as sample AD.

  In order to compare with these samples, as shown in the cross-sectional view of FIG. 22, a comparative sample B having a laminate that was not subjected to any processing at corners or ridges was prepared.

  As with sample A, the above battery was subjected to a three-point bending test in accordance with JIS-R1601, and the bending strength was measured. Also, a mounting test was conducted to examine the mounting failure rate. The results are shown in (Table 4) and (Table 5).

  The results shown in (Table 4) and (Table 5) show the same tendency as (Table 1) and (Table 2) of the first embodiment. That is, by providing the chamfered shape 31C and the chamfered shape at the corner and the ridge 31A, the bending strength of the all solid lithium secondary batteries of all other samples is higher than that of the comparative sample B. Further, by providing the R chamfered shape 32C and the chamfered shape before the green chip 32 is sintered, the bending strength is further increased.

  However, in the samples AE and AN having the radius of curvature of the R chamfered shape 31C of 20 μm and the samples AJ and AS having the chamfered width of 35 μm, a very high bending strength was not obtained. On the other hand, with respect to the thickness (0.9 mm) in the stacking direction of the laminate 31 without considering the R chamfered shape 31C, the samples AH and AR having a curvature radius exceeding 1/5 have a sufficient bending strength, but are flat. Since the part was small, it was difficult to stand still. The same applies to the samples AM and AV in which the chamfer width exceeds 1/4 with respect to the thickness of the stacked body 31 in the stacking direction not considering the chamfered shape. Since the stationary property is an essential requirement for mounting on the substrate, the radius of curvature is preferably 1/5 or less of the thickness of the stacked body 31 in the stacking direction without considering the R chamfered shape 31C. Similarly, the chamfer width is preferably equal to or less than ¼ of the thickness of the stacked body 31 in the stacking direction without considering the chamfered shape.

  In addition, regarding the mounting failure rate, 7% mounting failure occurred in the battery in which no processing was performed on the corners and ridges as shown in Comparative Sample B as shown in (Table 4) and (Table 5). . This is presumably because the outer current collectors 6A and 6C are thinned at the corners and ridges, and the laminate 31 is locally exposed to reduce the solder wettability. On the other hand, as shown in Sample AA to Sample AV, mounting defects can be reduced by providing R chamfered shapes 31C and chamfered shapes at corners and ridges 31A. Further, if the radius of curvature of the R chamfered shape 31C is 30 μm or more or the chamfer width is 45 μm or more, the mounting defect rate can be zero regardless of the order of the sintering process of the green chip 32.

  As described above, a high bending strength can be obtained by providing the R chamfered shape 31C and the chamfered shape at the corners and the ridges 31A of the laminated all solid lithium secondary battery. In addition, it is possible to reduce a mounting defect rate which is important for mounting on a substrate.

  Next, the results of examining the residual amount of plasticizer in the green chip 32 by changing the drying conditions before the R chamfered shape 32C is provided at the corner 32B and the ridge 32A of the green chip 32 will be described. In the production of Sample AW to Sample AY, the drying temperatures before providing the R chamfered shape 32C in the production of Sample AA were 150 ° C., 180 ° C., and 50 ° C., respectively. By drying at each temperature for 30 minutes, the remaining amount of the plasticizer was 50% by weight, 20% by weight, and 99% by weight. A laminated all solid lithium secondary battery of Samples AW, AX, and AY was produced in the same manner as Sample AA, except that such a green chip 32 was used. On the other hand, in the production of sample AZ, the green chip 32 was not dried before the R chamfered shape 32C was provided in the production of sample AA. That is, the remaining amount of the plasticizer was 100% by weight. A laminated all solid lithium secondary battery of Sample AZ was produced in the same manner as Sample AA, except for this.

  When the sample AZ was polished, no visible cracks or peelings were observed, but there were those in which impurities generated during polishing adhered to the surface due to the influence of the resin component contained in each green sheet. This is thought to be because the green chips are viscous and the components adhere to each other when the R chamfered shape 32C is processed. On the other hand, when the sample AX was polished, visible cracks and peeling of the green chip 32 were observed with a 5% probability. This is considered to be because the green chip 32 became brittle due to excessive drying. These defects were not confirmed in the samples AA, AW and AY in which the remaining amount of the plasticizer was 25% by weight or more and 99% by weight. From these results, it is preferable that the remaining amount of the plasticizer is 25 wt% to 99 wt% by drying before processing by polishing. This tendency was also confirmed when chamfering was performed by polishing.

  Next, the results of studying the influence of the abrasive material will be described. Sample BA used powder of the same material as solid electrolyte 1 as an abrasive when providing R chamfered shape 32C at corner 32B and ridge 32A of green chip 32 in preparation of sample AA. Except for this, a laminated all solid lithium secondary battery of Sample BA was obtained in the same manner as Sample AA. Sample BB used powder of the same material as solid electrolyte 1 as an abrasive when chamfering shapes were provided at corners 32B and ridges 32A of green chip 32 in the preparation of sample AB. Except for this, a laminated all solid lithium secondary battery of Sample BB was obtained in the same manner as Sample AB.

  The discharge capacity of each battery is shown in (Table 6). In an atmosphere with a dew point of −50 ° C. and 25 ° C., the battery was charged to 2.2 V and discharged to 1.0 V at a constant current of 10 μA.

  As shown in (Table 6), the discharge capacities of the samples BA and BB using the solid electrolyte material as the abrasive were improved from the discharge capacities of the samples AA and AB using alumina which is a normal abrasive. The reason for this is that charging / discharging reaction due to mixing of alumina occurred somewhat in Samples AA and AB, whereas in Samples BA and BB, it was a solid electrolyte material that did not hinder battery characteristics. it is conceivable that.

  Next, the effect of the sealing part 12 shown in FIG. 21 is demonstrated. In the preparation of sample CA, a sealing portion is obtained by applying a paste made of glass frit to a portion not covered with external current collectors 6A and 6C in the preparation of sample AA, and firing in a reducing atmosphere at 400 ° C. for 1 hour. 12 was provided. In this way, an all-solid lithium secondary battery of Sample CA was obtained.

  In the production of sample CB, a paste made of glass frit is further applied to the portion not covered with external current collectors 6A and 6C in the production of sample AB, and fired in a reducing atmosphere at 400.degree. 12 was provided. In this way, an all solid lithium secondary battery of Sample CB was obtained.

  In the preparation of the sample CC, the sealing portion 12 was provided by applying a water-resistant epoxy resin to a portion not covered with the external current collectors 6A and 6C in the preparation of the sample AA. In this way, an all-solid lithium secondary battery of Sample CC was obtained.

  Each of the above batteries was discharged after being stored in a constant temperature and humidity chamber at 60 ° C. and 85% for 30 days in a charged state, and the discharge capacity was measured. The results are shown in (Table 7). In an atmosphere with a dew point of −50 ° C. and 25 ° C., the battery was charged to 2.2 V at a constant current of 10 μA and discharged to 1.0 V.

  Samples AA and AB without the sealing part 12 have a larger discharge capacity after storage and excellent storage characteristics in the samples CA and CB with the sealing part 12 made of glass frit. Was confirmed. This effect is also confirmed in the sample CC using an epoxy resin as the material of the sealing portion 12. Thus, by providing the sealing portion 12 with a chemically stable material, the storage characteristics of the all-solid lithium secondary battery according to the present embodiment can be improved.

  The all-solid-state lithium secondary battery of the present invention can improve the reliability of the all-solid-state lithium secondary battery, and its applicability in applications that are provided on a mounting substrate is extremely high.

Sectional drawing of the all-solid-state lithium secondary battery by Embodiment 1 of this invention Sectional drawing for demonstrating the manufacturing method of the all-solid-state lithium secondary battery Sectional drawing for demonstrating the manufacturing method of the all-solid-state lithium secondary battery Perspective view of green chip in the manufacturing process of the all-solid lithium secondary battery Sectional drawing for demonstrating the manufacturing method of the all-solid-state lithium secondary battery Sectional drawing of the other all-solid-state lithium secondary battery by Embodiment 1 of this invention Sectional drawing of the further all-solid-state lithium secondary battery by Embodiment 1 of this invention Sectional drawing for demonstrating the manufacturing method of the all-solid-state lithium secondary battery shown in FIG. Sectional view of the all-solid-state lithium secondary battery of Comparative Sample A Sectional drawing for demonstrating the mounting test method of the all-solid-state lithium secondary battery by Embodiment 1 of this invention. Sectional drawing of the all-solid-state lithium secondary battery by Embodiment 2 of this invention Plan view for explaining the manufacturing method of the all solid lithium secondary battery Plan view for explaining the manufacturing method of the all solid lithium secondary battery Plan view for explaining the manufacturing method of the all solid lithium secondary battery Plan view for explaining the manufacturing method of the all solid lithium secondary battery Sectional drawing for demonstrating the manufacturing method of the all-solid-state lithium secondary battery Sectional drawing for demonstrating the manufacturing method of the all-solid-state lithium secondary battery Sectional drawing for demonstrating the manufacturing method of the all-solid-state lithium secondary battery (A) Plan view of the green chip in the manufacturing process of the all-solid lithium secondary battery (b) Cross-sectional view of the green chip on the XX plane (c) Cross-sectional view of the green chip on the Y-Y plane Sectional drawing for demonstrating the manufacturing method of the all-solid-state lithium secondary battery Sectional drawing of the other all-solid-state lithium secondary battery by Embodiment 2 of this invention Sectional view of an all-solid lithium secondary battery of Comparative Sample B

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Solid electrolyte 1G Green sheet of solid electrolyte 2 Positive electrode 2A Positive electrode active material layer 2B Positive electrode collector layer 2G Green sheet of positive electrode active material 2H Green sheet of positive electrode collector 3 Negative electrode 3A Negative electrode active material layer 3B Negative electrode collector layer 3G Green sheet of negative electrode active material 3H Green sheet of negative electrode current collector 4 Support base 5 Polyester film 6A, 6C External current collector 7 Carrier film 10 Negative electrode laminate green sheet 11 Positive electrode laminate green sheet 12 Sealing portion 21, 31 Laminate 21A, 22A, 31A, 32A Ridge 21C, 22C, 31C, 32C R chamfered shape 21D, 22D Chamfered shape 21E, 22E Width 22, 32 Green chip 22B, 32B Corner 23 Base material 23A Release agent layer 25, 33 Laminated sheet 41 Glass epoxy board 42 Wiring pattern 43 Solder

Claims (18)

Consists of a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, and a solid electrolyte interposed between the positive electrode and the negative electrode, and has a substantially rectangular parallelepiped shape with chamfered corners and ridges. A laminate provided with either a shape or an R chamfer shape;
An all-solid lithium secondary battery comprising a pair of external current collectors arranged at both ends of the laminate so as to sandwich the side surfaces of the laminate and connected to one of the positive electrode and the negative electrode, respectively. The positive electrode includes a positive electrode current collector and the positive electrode active material provided on the positive electrode current collector, and the negative electrode includes a negative electrode current collector and the negative electrode active material provided on the negative electrode current collector. The all-solid-state lithium secondary battery of Claim 1 which has a substance. The positive electrode is one of a plurality of positive electrodes, the negative electrode is one of a plurality of negative electrodes, the solid electrolyte is one of a plurality of solid electrolytes, and the stacked body includes one of the plurality of positive electrodes and the The all-solid-state lithium secondary battery according to claim 2, comprising a plurality of basic units including one of a plurality of negative electrodes and one of the plurality of solid electrolytes. The all-solid lithium secondary battery according to claim 3, wherein a layer of the same material as the solid electrolyte is provided on the outermost layer of the laminate. 2. The all solid lithium secondary battery according to claim 1, wherein a radius of curvature of the R chamfered shape is less than 1/5 of a length of the stacked body in a stacking direction and is 30 μm or more. 2. The all-solid lithium secondary battery according to claim 1, wherein a width of the chamfered shape is less than ¼ of a length in the stacking direction of the stacked body and is 45 μm or more. The all-solid-state lithium secondary battery according to claim 1, further comprising a sealing portion including at least one of glass and a resin mold that seals a portion of the laminate that is exposed from the external current collector. A step of producing a laminate having a substantially rectangular parallelepiped shape from a positive electrode, a negative electrode, and a solid electrolyte, and having either a chamfered shape or an R chamfered shape provided at a corner portion and a ridge portion;
And a B step of disposing external current collectors at both ends of the laminate so as to sandwich the side surfaces of the laminate. The A step includes
A first step of individually producing a positive electrode active material, a negative electrode active material, and a solid electrolyte green sheet;
A second step of sequentially laminating each green sheet in the order of a positive electrode active material, a solid electrolyte, and a negative electrode active material, to produce a laminated sheet;
A third step of cutting the laminated sheet to obtain a green chip;
A fourth step of applying either chamfering or R-chamfering to the corners and ridges of the green chip;
The method for manufacturing an all-solid-state lithium secondary battery according to claim 8, further comprising a fifth step of sintering the green chip after the fourth step. The manufacturing method of the all-solid-state lithium secondary battery of Claim 9 which has a drying step which is performed after the said 3rd step and makes the residual amount of the plasticizer in the said green chip 25 weight% or more before a process 99 weight%. The manufacturing method of the all-solid-state lithium secondary battery of Claim 9 which grind | polishes the corner part and ridge part of the said green chip in the said 4th step. The manufacturing method of the all-solid-state lithium secondary battery of Claim 11 using the powder of the same material as the said solid electrolyte as an abrasive | polishing agent in the said 4th step. In the first step, green sheets of a positive electrode active material, a negative electrode active material, and a solid electrolyte are individually produced on a plurality of releasable base materials, and each green sheet is formed from each of the plurality of base materials. The manufacturing method of the all-solid-state lithium secondary battery of Claim 9 which molds. The A step includes
A first step of individually producing a positive electrode active material, a positive electrode current collector, a negative electrode active material, a negative electrode current collector, and a solid electrolyte green sheet;
A second step in which a green sheet is sequentially laminated in the order of a positive electrode current collector, a positive electrode active material, a solid electrolyte, a negative electrode active material, and a negative electrode current collector;
A third step of cutting the laminated sheet to obtain a green chip;
A fourth step of applying either chamfering or R-chamfering to the corners and ridges of the green chip;
The method for manufacturing an all-solid-state lithium secondary battery according to claim 8, further comprising a fifth step of sintering the green chip after the fourth step. The manufacturing method of the all-solid-state lithium secondary battery of Claim 14 which has a drying step which is performed after the said 3rd step and makes the residual amount of the plasticizer in the said green chip | tip to 25 to 99 weight% before a process. The manufacturing method of the all-solid-state lithium secondary battery of Claim 14 which grind | polishes the corner part and ridge part of the said green chip in the said 4th step. The manufacturing method of the all-solid-state lithium secondary battery of Claim 16 using the powder of the same material as the said solid electrolyte as an abrasive | polishing agent in the said 4th step. In the second step, a stacking operation of sequentially stacking each green sheet in the order of a solid electrolyte, a negative electrode active material, a negative electrode current collector, a negative electrode active material, a solid electrolyte, a positive electrode active material, a positive electrode current collector, and a positive electrode active material is performed. The manufacturing method of the all-solid-state lithium secondary battery of Claim 14 which is performed in multiple times and produces a lamination sheet.

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