All-solid-state energy storage element

Abstract

The present invention provides an all-solid-state energy storage element in which the alloying reaction of metallic aluminum in the negative electrode substrate is sufficiently suppressed. [Solution] The all-solid-state energy storage element 1 according to one aspect of the present invention uses lithium ions as charge transport ions and has a laminated structure comprising a negative electrode substrate 11, a negative electrode active material layer 12, and a solid electrolyte layer 13 in this order, wherein the negative electrode substrate has a substrate layer 16 containing metallic aluminum and a coating layer 17 which is laminated over the entire surface of the substrate layer on the negative electrode active material layer side, and the negative electrode active material layer has an operating potential of 0.5V (vs.Li / Li + The negative electrode active material contains a negative electrode active material which may be less than or equal to the specified value, and the peripheral edge 19 of the surface of the negative electrode active material layer on the negative electrode substrate does not have an ion-conducting member, or the side surface of the substrate layer is covered with a member A20 which does not have ion conductivity.

Description

Technical Field

[0001] The present invention relates to all-solid-state energy storage elements.

Background Art

[0002] Non-aqueous electrolyte secondary batteries represented by lithium-ion secondary batteries are widely used in electronic devices such as personal computers and communication terminals, and automobiles, etc. due to their high energy density. A non-aqueous electrolyte secondary battery generally has a pair of electrodes electrically isolated from each other and a non-aqueous electrolyte interposed therebetween, and is configured to charge and discharge by transferring charge-transporting ions between both electrodes. As energy storage elements other than non-aqueous electrolyte secondary batteries, capacitors such as lithium-ion capacitors and electric double layer capacitors are also widely used. In recent years, as a non-aqueous electrolyte, an all-solid-state energy storage element using a solid electrolyte such as a sulfide solid electrolyte, an oxide solid electrolyte, or a polymer solid electrolyte instead of a non-aqueous electrolyte solution in which an electrolyte salt is dissolved in a liquid such as an organic solvent has been proposed.

[0003] The negative electrode of a non-aqueous electrolyte energy storage element usually has a structure in which a negative electrode active material layer is laminated on a negative electrode substrate. Copper is widely used for the negative electrode substrate, and from the viewpoints of weight reduction and cost reduction, etc., it has also been proposed to use an aluminum-made negative electrode substrate (see Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As a negative electrode of an all-solid-state energy storage element using lithium ions as charge-transporting ions, on a negative electrode substrate containing metallic aluminum, an operating potential of 0.5 V (vs. Li / Li +When a negative electrode is used in which a negative electrode active material layer containing a negative electrode active material up to the following level is laminated, an alloying reaction of metallic aluminum in the negative electrode substrate (alloying reaction of metallic aluminum and metallic lithium) may proceed as the all-solid-state energy storage element charges and discharges. If the alloying reaction of metallic aluminum contained in the negative electrode substrate proceeds, the Coulomb efficiency of the all-solid-state energy storage element decreases. In order to suppress such alloying reactions, the use of a negative electrode substrate provided with a coating layer such as a carbon coating layer has been considered. However, even when a negative electrode substrate provided with such a coating layer is used, the alloying reaction of metallic aluminum cannot be sufficiently suppressed.

[0006] The object of the present invention is to provide an all-solid-state energy storage element in which the alloying reaction of metallic aluminum in the negative electrode substrate is sufficiently suppressed. [Means for solving the problem]

[0007] An all-solid-state energy storage element according to one aspect of the present invention uses lithium ions as charge transport ions and has a laminated structure comprising a negative electrode substrate, a negative electrode active material layer, and a solid electrolyte layer in this order, wherein the negative electrode substrate comprises a substrate layer containing metallic aluminum and a coating layer laminated over the entire surface of the substrate layer on the side facing the negative electrode active material layer, and the negative electrode active material layer has an operating potential of 0.5V (vs.Li / Li + The negative electrode active material contains a negative electrode active material which may be less than or equal to the specified value, and the peripheral edge of the surface of the negative electrode active material layer on the negative electrode substrate does not have an ion-conducting member, or the side surface of the substrate layer is covered with a member A which does not have ion conductivity. [Effects of the Invention]

[0008] In one aspect of the present invention, the all-solid-state energy storage element has sufficient suppression of the alloying reaction of the metallic aluminum in the negative electrode substrate. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic cross-sectional view of an all-solid-state energy storage element according to a first embodiment of the present invention. [Figure 2]Figure 2 is a schematic cross-sectional view of an all-solid-state energy storage element according to a second embodiment of the present invention. [Figure 3] Figure 3 is a schematic cross-sectional view of an all-solid-state energy storage element according to a third embodiment of the present invention. [Figure 4] Figure 4 is a schematic cross-sectional view of an all-solid-state energy storage element according to a fourth embodiment of the present invention. [Figure 5] Figure 5 is a schematic cross-sectional view of an all-solid-state energy storage element according to a fifth embodiment of the present invention. [Figure 6] Figure 6 is a schematic cross-sectional view of an all-solid-state energy storage element according to a sixth embodiment of the present invention. [Figure 7] Figure 7 is a schematic cross-sectional view of an all-solid-state energy storage element according to the seventh embodiment of the present invention. [Figure 8] Figure 8 is a schematic cross-sectional view of an all-solid-state energy storage element according to the eighth embodiment of the present invention. [Figure 9A] Figure 9A is a first schematic cross-sectional view showing a method for manufacturing an all-solid-state energy storage element according to the first embodiment of the present invention. [Figure 9B] Figure 9B is a second schematic cross-sectional view showing a method for manufacturing an all-solid-state energy storage element according to the first embodiment of the present invention. [Figure 9C] Figure 9C is a third schematic cross-sectional view showing a method for manufacturing an all-solid-state energy storage element according to the first embodiment of the present invention. [Figure 10] Figure 10 is a schematic diagram showing an energy storage device configured by assembling a plurality of all-solid-state energy storage elements according to the first embodiment of the present invention. [Figure 11] Figure 11 is a schematic cross-sectional view of the all-solid-state energy storage element of Comparative Example 1. [Modes for carrying out the invention]

[0010] First, an overview of the all-solid-state energy storage elements disclosed herein will be provided.

[0011] (1) An all-solid-state energy storage element according to one aspect of the present invention uses lithium ions as charge transport ions and has a laminated structure comprising a negative electrode substrate, a negative electrode active material layer and a solid electrolyte layer in this order, wherein the negative electrode substrate comprises a substrate layer containing metallic aluminum and a coating layer laminated over the entire surface of the substrate layer on the side facing the negative electrode active material layer, and the negative electrode active material layer has an operating potential of 0.5V (vs.Li / Li + The negative electrode active material contains a negative electrode active material which may be less than or equal to the specified value, and the peripheral edge of the surface of the negative electrode active material layer on the negative electrode substrate does not have an ion-conducting member, or the side surface of the substrate layer is covered with a member A which does not have ion conductivity.

[0012] In the all-solid-state energy storage element described in (1) above, the alloying reaction of the metallic aluminum in the negative electrode substrate is sufficiently suppressed. The reason for this is not clear, but the following reasons are speculated. In conventional all-solid-state energy storage elements, where a coating layer is laminated onto a base layer containing metallic aluminum, and a negative electrode active material layer is laminated on this coating layer, the sides of the base layer are usually exposed. Therefore, for example, during pressing in the manufacturing of the all-solid-state energy storage element, the negative electrode active material layer may stretch, and the edges of the negative electrode active material layer may come into contact with the sides of the base layer. Also, the presence of burrs generated when the negative electrode base layer is cut or punched can cause contact between the burrs on the sides of the base layer and the negative electrode active material layer. Thus, contact between the sides of the base layer and the negative electrode active material layer is considered to be one of the causes of alloying of the metallic aluminum in the base layer. Similarly, contact between the sides of the base layer and the solid electrolyte layer also causes alloying of the metallic aluminum in the base layer. In contrast, in the case of the all-solid-state energy storage element described in (1) above, in the first embodiment, no ion-conducting material is placed on the peripheral edge of the surface of the negative electrode substrate on the negative electrode active material layer side (see embodiments in Figures 1 to 7). The negative electrode active material layer containing the solid electrolyte, the solid electrolyte layer, etc., correspond to the ion-conducting material. In the second embodiment, the side surface of the substrate layer is covered with a material A that does not have ion conductivity (see embodiment in Figure 8). In such an embodiment, even if the negative electrode active material layer stretches slightly or burrs are present on the substrate layer, contact between the side surface of the substrate layer and the negative electrode active material layer is suppressed. Furthermore, with the structure of the all-solid-state energy storage element described in (1) above, contact between the side surface of the substrate layer and the solid electrolyte layer is also suppressed. For this reason, it is presumed that the alloying reaction of metallic aluminum in the negative electrode substrate is sufficiently suppressed in the all-solid-state energy storage element described in (1) above.

[0013] "Having electronic conductivity" means that the volume resistivity is 10 -2 This means that it is less than or equal to Ω·cm. The volume resistivity shall be the value measured in accordance with JIS-H-0505 (1975). On the other hand, "having no electronic conductivity" or "having (electrical) insulating properties" means that the above volume resistivity is 10 7 This means it is greater than or equal to Ω·cm.

[0014] A "material having ionic conductivity" is defined as having an ionic conductivity of 10 at 25°C. -10 This refers to materials with an ionic conductivity of mS / cm or higher. "Materials without ionic conductivity" means that the ionic conductivity at 25°C is 10 -10 This refers to components with a density of less than mS / cm. The ionic conductivity is a value obtained based on alternating current impedance measurement, which is measured by setting the temperature of the member to be measured, enclosed in an ionic conductivity measurement cell using a platinum electrode, which is a blocking electrode, as a counter electrode, using "VMP-300" manufactured by Biologic as a measuring device, to 25°C. Specifically, it is obtained by the following procedure. Perform alternating current impedance measurement using the above measuring device, and illustrate the results as a Nyquist plot. The measurement conditions are an applied voltage amplitude of 5 mV, a frequency range from 1 MHz to 100 mHz, and a measurement temperature of 25°C. In the case of a member where no arc component is seen in the Nyquist plot, if the value on the imaginary axis is less than 0 at all measurement points, the value on the real axis at the measurement point on the highest frequency side is taken as the resistance R, and in other cases, the value on the real axis at the intersection of the approximate straight line of the measurement points and the real axis is taken as the resistance R. In the case of a member where an arc component is seen in the Nyquist plot, the value on the real axis at the end point on the low frequency side of the arc is taken as the resistance R. Ionic conductivity σ 25 (mS / cm) is obtained by the following formula (A) using the resistance R (Ω), the electrode distance L (cm), and the electrode area A (cm 2 ). σ 25 = L / (RA) ···(A)

[0015] (2) In the all-solid-state battery element described in (1) above, a member B having no ionic conductivity may be disposed at least in part at the peripheral edge of the surface on the negative electrode active material layer side of the negative electrode substrate.

[0016] In the all-solid-state battery element described in (2) above, due to the presence of the member B having no ionic conductivity disposed at least in part at the peripheral edge of the surface on the negative electrode active material layer side of the negative electrode substrate, the contact between the side surface of the substrate layer and the negative electrode active material layer is further suppressed. Therefore, according to the all-solid-state battery element described in (2) above, the alloying reaction of the metal aluminum of the negative electrode substrate is more sufficiently suppressed.

[0017] (3) In the all-solid-state battery element described in (1) or (2) above, at least a part of the peripheral edge of the surface on the negative electrode active material layer side of the negative electrode substrate may be exposed.

[0018] In the all-solid-state energy storage element described in (3) above, the alloying reaction of metallic aluminum in the negative electrode substrate is sufficiently suppressed.

[0019] (4) In the all-solid-state energy storage element described in any one of (1) to (3) above, the average thickness of the coating layer may be 0.01 μm or more and 20 μm or less.

[0020] In the all-solid-state energy storage element described in (4) above, the alloying reaction of metallic aluminum in the negative electrode substrate is sufficiently suppressed.

[0021] This paper details an all-solid-state energy storage element, a method for manufacturing the all-solid-state energy storage element, an energy storage device, and other embodiments relating to one embodiment of the present invention.

[0022] <All-solid-state energy storage element> As one embodiment of the all-solid-state energy storage element of the present invention, an all-solid-state secondary battery will be described below as a specific example.

[0023] (All-solid-state energy storage element 1) The all-solid-state energy storage element 1 shown in Figure 1 uses lithium ions as charge transport ions and has a laminated structure comprising a negative electrode substrate 11, a negative electrode active material layer 12, a solid electrolyte layer 13, a positive electrode active material layer 14, and a positive electrode substrate 15 in this order. The negative electrode substrate 11, negative electrode active material layer 12, solid electrolyte layer 13, positive electrode active material layer 14, and positive electrode substrate 15 may each be plate-shaped, such as a square (preferably rectangular or square) or circular shape in plan view. In the all-solid-state energy storage element 1, the negative electrode is formed by the negative electrode substrate 11 and the negative electrode active material layer 12. The positive electrode is formed by the positive electrode active material layer 14 and the positive electrode substrate 15.

[0024] The negative electrode substrate 11 has a substrate layer 16 containing metallic aluminum and a coating layer 17. The coating layer 17 is laminated over the entire surface of the substrate layer 16 on the side facing the negative electrode active material layer 12. That is, the all-solid-state energy storage element 1 has a laminated structure comprising the substrate layer 16, coating layer 17, negative electrode active material layer 12, solid electrolyte layer 13, positive electrode active material layer 14, and positive electrode substrate 15 in this order.

[0025] In the all-solid-state energy storage element 1, the area of ​​the negative electrode substrate 11 in the stacking direction is larger than the area of ​​the negative electrode active material layer 12 in the stacking direction. Also, in the stacking direction, the negative electrode active material layer 12 is stacked on the central portion 18 of the negative electrode substrate 11. In other words, in the stacking direction, the outer edge of the negative electrode active material layer 12 is located inside the outer edge of the negative electrode substrate 11. That is, the surface of the negative electrode substrate 11 on the negative electrode active material layer 12 side has a central portion 18 where the negative electrode active material layer 12 is stacked and a peripheral portion 19 where the negative electrode active material layer 12 is not stacked. The peripheral portion 19 of the negative electrode substrate 11 is a region that includes the outer edge of the negative electrode substrate 11.

[0026] In the all-solid-state energy storage element 1, a non-ionic conductive member 20 (member B) is provided on at least a portion of the peripheral edge of the surface of the negative electrode substrate 11 facing the negative electrode active material layer 12. In the all-solid-state energy storage element 1 of this embodiment, the non-ionic conductive member 20 is laminated over the entire peripheral edge 19 of the surface of the negative electrode substrate 11 facing the negative electrode active material layer 12. In this embodiment, the non-ionic conductive member 20 is provided in contact with the side surface of the negative electrode active material layer 12. In other words, the non-ionic conductive member 20 is provided so as to cover the entire side surface of the negative electrode active material layer 12. That is, no ionic conductive member is provided on the peripheral edge 19 of the surface of the negative electrode substrate 11 facing the negative electrode active material layer 12 of the all-solid-state energy storage element 1.

[0027] In the all-solid-state energy storage element 1, a member 20 that does not have ion conductivity is arranged on the peripheral edge 19 of the surface of the negative electrode substrate 11 facing the negative electrode active material layer 12, and no member with ion conductivity is arranged on the peripheral edge 19 of the surface of the negative electrode substrate 11 facing the negative electrode active material layer 12. Therefore, with the all-solid-state energy storage element 1, contact between the side surface of the substrate layer 16 of the negative electrode substrate 11 and the negative electrode active material layer 12 and the solid electrolyte layer 13 is suppressed, and the alloying reaction of metallic aluminum contained in the substrate layer 16 is sufficiently suppressed.

[0028] In the case of the all-solid-state energy storage element 1, when viewed in the stacking direction, the outer edge of the negative electrode substrate 11 coincides with the outer edge of the non-ionic conductive member 20 located on the peripheral edge 19 of the negative electrode active material layer 12 side of the negative electrode substrate 11, and the outer edge of the solid electrolyte layer 13 is located inside these outer edges. Similarly, the outer edge of the positive electrode active material layer 14 coincides with the outer edge of the positive electrode substrate 15, and these outer edges are located inside the outer edge of the solid electrolyte layer 13. However, the relative sizes of each layer are not limited to this configuration.

[0029] For example, the area of ​​the negative electrode active material layer 12 in the stacking direction may be larger than the area of ​​the positive electrode active material layer 14 in the stacking direction. In this case, the outer edge of the negative electrode active material layer 12 may be positioned outside the outer edge of the positive electrode active material layer 14 in the stacking direction.

[0030] (All-solid-state energy storage element 2) As shown in the all-solid-state energy storage element 2 of Figure 2, the outer edge of the negative electrode substrate 11, the outer edge of the non-ionic conductive member 20 located on the peripheral edge 19 of the negative electrode active material layer 12 side of the negative electrode substrate 11, and the outer edge of the solid electrolyte layer 13 may coincide in the view in the stacking direction.

[0031] (All-solid-state energy storage element 3) As shown in the all-solid-state energy storage element 3 in Figure 3, the solid electrolyte layer 13 may be provided so as to cover the side surface of the positive electrode active material layer 14. Also, as shown in the all-solid-state energy storage element 3 in Figure 3, the side surface of the negative electrode active material layer 12 and the non-ionic conductive member 20 do not have to be in contact. In the all-solid-state energy storage element 3 in Figure 3, in a view in the stacking direction, the outer edge of the negative electrode substrate 11, the outer edge of the non-ionic conductive member 20, the outer edge of the solid electrolyte layer 13, and the outer edge of the positive electrode substrate 15 coincide.

[0032] (All-solid-state energy storage element 4) As shown in the all-solid-state energy storage element 4 of Figure 4, a member 20 that does not have ion conductivity may be placed between the peripheral edge 19 of the negative electrode substrate 11 on the negative electrode active material layer 12 side and the peripheral edge of the negative electrode active material layer 12 on the negative electrode substrate 11 side that is not directly laminated on the negative electrode substrate 11.

[0033] In all solid-state energy storage elements 2 to 4, no ion-conducting material is placed on the peripheral edge 19 of the negative electrode substrate 11 on the side facing the negative electrode active material layer 12. Therefore, in all solid-state energy storage elements 2 to 4, contact between the side surface of the substrate layer 16 of the negative electrode substrate 11 and the negative electrode active material layer 12 and the solid electrolyte layer 13 is suppressed, and the alloying reaction of metallic aluminum contained in the substrate layer 16 is sufficiently suppressed.

[0034] In another embodiment of the present invention, if an ion-conducting member is not disposed on the peripheral edge of the surface of the negative electrode substrate facing the negative electrode active material layer, then a member that does not have to be disposed on the side surface of the negative electrode active material layer.

[0035] (All-solid-state energy storage element 5) The all-solid-state energy storage element 5 in Figure 5, like the all-solid-state energy storage element 1 in Figure 1, comprises a negative electrode substrate 11, a negative electrode active material layer 12, a solid electrolyte layer 13, a positive electrode active material layer 14, and a positive electrode substrate 15 in that order, with the negative electrode substrate 11 having a substrate layer 16 and a coating layer 17. In the all-solid-state energy storage element 5, the area of ​​the negative electrode substrate 11 in the stacking direction is larger than the area of ​​the negative electrode active material layer 12 in the stacking direction. Also, in the stacking direction, the negative electrode active material layer 12 is stacked on the central part 18 of the negative electrode substrate 11. In other words, in the stacking direction, the outer edge of the negative electrode active material layer 12 is located inside the outer edge of the negative electrode substrate 11. That is, the surface of the negative electrode substrate 11 on the negative electrode active material layer 12 side has a central part 18 where the negative electrode active material layer 12 is stacked and a peripheral part 19 where the negative electrode active material layer 12 is not stacked.

[0036] Unlike all-solid-state energy storage elements such as 1, the all-solid-state energy storage element 5 does not have a non-ionic conductive material on the peripheral edge 19 of the negative electrode substrate 11 facing the negative electrode active material layer 12. That is, in the all-solid-state energy storage element 5, at least a part of the peripheral edge 19 of the negative electrode substrate 11 facing the negative electrode active material layer 12 is exposed. In the all-solid-state energy storage element 5, the entire peripheral edge 19 is exposed.

[0037] In the all-solid-state energy storage element 5, no ion-conducting material is placed on the peripheral edge 19 of the negative electrode substrate 11 on the side facing the negative electrode active material layer 12. Due to this structure, in the all-solid-state energy storage element 5, contact between the side surface of the substrate layer 16 of the negative electrode substrate 11 and the negative electrode active material layer 12 and the solid electrolyte layer 13 is suppressed, and the alloying reaction of metallic aluminum contained in the substrate layer 16 is sufficiently suppressed.

[0038] The lower limit of the width W of the peripheral edge 19 on the side of the negative electrode substrate 11 facing the negative electrode active material layer 12 is preferably, for example, 1 times the average thickness of the negative electrode active material layer 12, and more preferably 2 times, 5 times, 10 times, or 20 times the average thickness of the negative electrode active material layer 12. Having a sufficient width in this way allows for more adequate suppression of contact between the side surface of the substrate layer 16 of the negative electrode substrate 11 and the negative electrode active material layer 12 and the solid electrolyte layer 13. The upper limit of the width W may be, for example, 10,000 times the average thickness of the negative electrode active material layer 12, or it may be 2,000 times, 1,000 times, 500 times, or 200 times. By setting the width W to be below the above upper limit, it is possible to miniaturize the all-solid-state energy storage element 5. If the width W of the peripheral edge 19 is not constant, the width of the shortest part shall be used.

[0039] In the all-solid-state energy storage element 5, the outer edges of the negative electrode active material layer 12, the solid electrolyte layer 13, the positive electrode active material layer 14, and the positive electrode substrate 15 coincide when viewed in the stacking direction. However, the relative sizes of each layer are not limited to this configuration.

[0040] (All-solid-state energy storage elements 6, 7) As shown in the all-solid-state energy storage element 6 in Figure 6, the solid electrolyte layer 13 may be provided so as to cover the side surface of the negative electrode active material layer 12. As shown in the all-solid-state energy storage element 7 in Figure 7, the solid electrolyte layer 13 may be provided so as to cover the side surface of the positive electrode active material layer 14. In the all-solid-state energy storage element 6 or 7, no ion-conducting member is provided on the peripheral edge 19 of the negative electrode substrate 11 on the side facing the negative electrode active material layer 12. Therefore, in the all-solid-state energy storage element 6 or 7, contact between the side surface of the substrate layer 16 of the negative electrode substrate 11 and the negative electrode active material layer 12 and solid electrolyte layer 13 is suppressed, and the alloying reaction of metallic aluminum contained in the substrate layer 16 is sufficiently suppressed.

[0041] (All-solid-state energy storage element 8) In another embodiment of the present invention, contact between the side surface of the substrate layer and the negative electrode active material layer and the solid electrolyte layer may be suppressed by covering the side surface of the substrate layer with a non-ionic conductive material. In this configuration, an ionic conductive material may or may not be provided at the peripheral edge of the side surface of the negative electrode substrate facing the negative electrode active material layer.

[0042] The all-solid-state energy storage element 8 in Figure 8, like the all-solid-state energy storage element 1 in Figure 1, comprises a negative electrode substrate 11, a negative electrode active material layer 12, a solid electrolyte layer 13, a positive electrode active material layer 14, and a positive electrode substrate 15 in that order, with the negative electrode substrate 11 having a substrate layer 16 and a coating layer 17. In the all-solid-state energy storage element 8, the side surface of the substrate layer 16 is covered with a non-ionic conductive member 20 (member A). In this embodiment, the entire side surface of the negative electrode substrate 11 is covered with a non-ionic conductive member 20.

[0043] Thus, in the all-solid-state energy storage element 8, the side surface of the base layer 16 of the negative electrode base material 11 is covered with a member 20 that does not have ion conductivity. Therefore, contact between the side surface of the base layer 16 of the negative electrode base material 11 and the negative electrode active material layer 12 and the solid electrolyte layer 13 is suppressed, and the alloying reaction of metallic aluminum contained in the base layer 16 is suppressed.

[0044] An all-solid-state energy storage element according to one embodiment of the present invention may further include other components such as a container. In the all-solid-state energy storage elements 1 to 8 shown in Figures 1 to 8, other components such as a container are omitted. An all-solid-state energy storage element according to one embodiment of the present invention may further include, for example, a positive electrode lead, a positive electrode external terminal, a negative electrode lead, and a negative electrode external terminal. The positive electrode lead and the negative electrode lead are housed inside the container. The positive electrode external terminal and the negative electrode external terminal are provided outside the container. The positive electrode is electrically connected to the positive electrode external terminal via the positive electrode lead. The negative electrode is electrically connected to the negative electrode external terminal via the negative electrode lead.

[0045] The main components of the all-solid-state energy storage element according to one embodiment of the present invention will be described in detail below. Note that the lower and upper limits of the numerical ranges described in the embodiment of the present invention can be combined in any way.

[0046] (Positive electrode substrate) The positive electrode substrate is electrically conductive. The positive electrode substrate is typically connected to the positive electrode lead described above.

[0047] Examples of materials for the positive electrode substrate include metals such as aluminum, titanium, iron, and their alloys (stainless steel, etc.). Among these, pure aluminum or aluminum alloys are preferred from the viewpoint of high potential resistance, high electronic conductivity, and cost.

[0048] The positive electrode substrate has a shape such as a sheet or a plate. Examples of positive electrode substrate forms include foil, vapor-deposited film, mesh, and porous material, with foil being preferred. The positive electrode substrate may be, for example, pure aluminum foil or aluminum alloy foil.

[0049] The average thickness of the positive electrode substrate may be, for example, 3 μm or more and 50 μm or less. The lower limit of the average thickness of the positive electrode substrate may be 5 μm, 8 μm, 10 μm, or 15 μm. The upper limit of the average thickness of the positive electrode substrate may be 40 μm, 30 μm, 20 μm, or 15 μm.

[0050] The positive electrode substrate may be provided with a coating layer. The coating layer of the positive electrode substrate may include, for example, a conductive agent and a binder. When such a coating layer containing a conductive agent is provided on the positive electrode substrate, the contact resistance between the positive electrode substrate and the positive electrode active material layer can be reduced. Examples of conductive agents and binders used in the coating layer of the positive electrode substrate are the same as those used in the positive electrode active material layer, as described later.

[0051] (Cathode active material layer) The positive electrode active material layer contains a positive electrode active material. The positive electrode active material layer may optionally contain components such as a solid electrolyte, conductive agent, binder, thickener, and filler. The positive electrode active material layer may also be formed from a positive electrode mixture containing the positive electrode active material and other optional components.

[0052] A known positive electrode active material can be used for the positive electrode active material. The all-solid-state energy storage element according to one embodiment of the present invention is an all-solid-state energy storage element that uses lithium ions as charge transport ions. In this all-solid-state energy storage element, at least one of the positive electrode active material and the negative electrode active material (described later) typically contains the element lithium. For a positive electrode active material used in an all-solid-state energy storage element that uses lithium ions as charge transport ions, a material capable of intercalating and releasing lithium ions is typically used. Examples of positive electrode active materials include lithium transition metal composite oxides, polyanion compounds, chalcogen compounds, sulfur-based materials, and lithium oxide. One or more positive electrode active materials can be used.

[0053] Examples of transition metal elements included in lithium transition metal composite oxides include nickel, cobalt, and manganese. Lithium transition metal composite oxides may also contain typical metal elements such as aluminum. Examples of lithium transition metal composite oxides include those having an α-NaFeO2 crystal structure and those having a spinel crystal structure.

[0054] Li 1+α Ma 1-αThose represented by O2(Ma is a metal element other than lithium element, containing one or more transition metal elements. 0 ≦ α < 1). Ma preferably contains one or more of Ni, Co and Mn. The total content of Ni, Co and Mn with respect to Ma ((Ni + Co + Mn) / Ma) is preferably 90 mol% or more, more preferably 98 mol% or more.

[0055] As the lithium transition metal composite oxide having a spinel-type crystal structure, Li β Those represented by Mb2O4 (Mb is a metal element other than lithium element, containing one or more transition metal elements. 0 < β ≦ 1.2). Mb preferably contains Mn. The content of Mn with respect to Mb (Mn / Mb) is preferably 50 mol% or more, more preferably 80 mol% or more.

[0056] The polyanion compound is a compound composed of a polyanion (that is, a polyvalent oxoacid anion) and a cation. The polyanion compound preferably contains a lithium cation and a transition metal cation as the cation. Examples of the polyanion compound include LiFePO4, LiMnPO4, LiMn x Fe 1-x PO4 (0 < x < 1), LiNiPO4, LiCoPO4, Li3V2(PO4)3, Li2MnSiO4, Li2CoPO4F, etc. The surface of the particles of the polyanion compound may be coated with other materials (such as the carbon material described later).

[0057] Examples of the chalcogen compound include titanium disulfide, molybdenum disulfide, molybdenum dioxide, etc.

[0058] Examples of the sulfur-based material include elemental sulfur, metal sulfides such as lithium sulfide, organic disulfide compounds, and organic sulfur compounds such as carbon sulfide compounds.

[0059] The atoms or polyanions in these materials, which are the positive electrode active materials, may be partially substituted with atoms or anions of other elements. These materials may also be coated on the surface with other materials.

[0060] The positive electrode active material is usually in particulate form. The average particle size of the positive electrode active material is preferably, for example, 0.1 μm or more and 20 μm or less. Setting the average particle size of the positive electrode active material above the lower limit facilitates the manufacture and handling of the positive electrode active material. Setting the average particle size of the positive electrode active material below the upper limit improves the electronic conductivity of the positive electrode active material layer. When a composite material of the positive electrode active material and other materials is used, the average particle size of the composite material is considered the average particle size of the positive electrode active material. "Average particle size" refers to the value (D50) where the volume-based integrated distribution calculated according to JIS-Z-8819-2 (2001), based on the particle size distribution measured by laser diffraction / scattering on a dilution of particles diluted with a solvent, in accordance with JIS-Z-8825 (2013), becomes 50%. For obtaining particles of the positive electrode active material and the negative electrode active material described later with a predetermined particle size, known methods using, for example, pulverizers and classifiers can be employed.

[0061] The content of the positive electrode active material in the positive electrode active material layer is preferably 50% to 99% by mass, more preferably 70% to 98% by mass, and may also be 80% to 95% by mass. By setting the content of the positive electrode active material within the above range, it is possible to achieve both high energy density and manufacturability in the positive electrode active material layer.

[0062] A solid electrolyte refers to an electrolyte that maintains a solid state at 25°C under a nitrogen atmosphere. The solid electrolyte used in the all-solid-state energy storage element according to one embodiment of the present invention has lithium ion conductivity. Examples of solid electrolytes include sulfide solid electrolytes, oxide solid electrolytes, dry polymer electrolytes, gel polymer electrolytes, and pseudo-solid electrolytes, with sulfide solid electrolytes being preferred. The solid electrolyte may also be a solid electrolyte other than an oxide solid electrolyte. The upper limit of the oxygen element content in the solid electrolyte may be 10 mol%, 1 mol%, or 0.1 mol%. The solid electrolyte may be a crystalline solid electrolyte or an amorphous solid electrolyte. A crystalline solid electrolyte refers to a solid electrolyte in which peaks originating from the solid electrolyte are observed in the X-ray diffraction pattern. An amorphous solid electrolyte refers to a solid electrolyte in which the X-ray diffraction pattern is a halo pattern in which substantially no peaks other than those originating from the raw materials are observed. One or more types of solid electrolytes can be used.

[0063] The sulfide solid electrolyte preferably contains at least the element of sulfur and more preferably the element of lithium. The sulfide solid electrolyte may also preferably contain the element of phosphorus and more preferably the element of halogen. The sulfide solid electrolyte preferably contains at least one of the elements of bromine and iodine as the halogen element.

[0064] When a sulfide solid electrolyte is a crystalline solid electrolyte, its crystal structure can be an argyrodite type crystal structure, a Li3PS4 crystal structure, a Li4P2S6 crystal structure, or a Li7P3S crystal structure. 11 Crystal structure, Li 10 GeP2S 12Examples of sulfide solid electrolytes include crystal structures such as crystalline structures, thio-LISICON type crystal structures, inverse fluorite type crystal structures, crystal structures (High Ion Conduction Phase: HICP) having diffraction peaks in the ranges of 19.9°±0.5° and 29.3°±0.5° in X-ray diffraction patterns using CuKα rays, crystal structures (Low Ion Conduction Phase: LICP) having diffraction peaks in the ranges of 21.0±0.5° and 28.0±0.5° in X-ray diffraction patterns using CuKα rays, and crystal structures having different diffraction peaks in the ranges of 17.9°±0.5° or 19.1°±0.5°, 29.1°±0.5°, and 29.8°±0.5°, with one of these diffraction peaks being the largest diffraction peak.

[0065] Examples of sulfide solid electrolytes include Li2S-P2S5, Li2S-P2S5-LiI, Li2S-P2S5-LiCl, Li2S-P2S5-LiBr, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-P2S5-Li3N, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, and Li2S-P2S5-Z. m S 2n (However, m and n are positive numbers, and Z is one of Ge, Zn, or Ga.) Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li x MO y (However, x and y are positive numbers, and M is one of P, Si, Ge, B, Al, Ga, or In.) Li 10 GeP2S 12 These are some examples.

[0066] In the positive electrode active material layer, a portion of the solid electrolyte may form a composite with the positive electrode active material. Such a composite may further contain other components (e.g., conductive agents) in addition to the solid electrolyte and positive electrode active material.

[0067] When the positive electrode active material layer contains a solid electrolyte, the content of the solid electrolyte in the positive electrode active material layer is preferably 5% by mass or more and 50% by mass or less, but may also be 10% by mass or more and 40% by mass or less, or 15% by mass or more and 30% by mass or less.

[0068] Conductive agents are typically components made of materials that have electronic conductivity. Even if the volume resistivity of the conductive agent cannot be directly measured, the volume resistivity is 10 -2 Materials known to have a conductivity of Ω·cm or less are classified as conductive agents. Examples of conductive agents include carbon materials, metals, and electronically conductive ceramics. A carbon material is a material whose main constituent element is carbon. The main constituent element is the element with the highest mass content. For example, the carbon content in a carbon material may be 80% by mass or more, 90% by mass or more, 95% by mass, 99% by mass, or 99.9% by mass or more. It is preferable that the carbon material is a carbon material other than a non-carbonized polymer compound. Examples of carbon materials include graphite, non-graphitic carbon, and graphene-based carbon. Examples of non-graphitic carbon include carbon nanofibers, pitch-based carbon fibers, and carbon black. Examples of carbon black include furnace black, acetylene black, and Ketjen black. Examples of graphene-based carbon include graphene, carbon nanotubes (CNTs), and fullerenes. Conductive agents can take the form of powder or fibers. One or more types of conductive agents can be used. These materials may also be used as a composite of conductive agents. For example, a composite material of carbon black and CNTs may be used.

[0069] The conductive agent content in the positive electrode active material layer is preferably 0.1% by mass or more and 10% by mass or less, more preferably 1% by mass or more and 9% by mass or less, and even more preferably 3% by mass or more and 8% by mass or less. The upper limit of the conductive agent content may be 5% by mass, 4% by mass, or 3% by mass. By setting the conductive agent content within the above range, it is possible to increase the energy density of the all-solid-state energy storage element.

[0070] Examples of binders include water-based binders and organic solvent-based binders.

[0071] A water-based binder is a binder that dissolves or disperses in water. A water-based binder may be one that dissolves or disperses in 100 parts by mass or more per 100 parts by mass of water at 20°C. When forming a positive electrode active material layer using a paste-like positive electrode mixture in which the dispersion medium is water or a mixed solvent mainly composed of water, a water-based binder (water-soluble or water-dispersible polymer material) can be used. Examples of water-based binders include polyethylene oxide, polypropylene oxide, polyvinyl alcohol, polyacrylic acid, polymethacrylic acid, polytetrafluoroethylene, styrene-butadiene rubber, polyethylene, polypropylene, nitrile-butadiene rubber, and cellulose.

[0072] An organic solvent-based binder is a binder that dissolves or disperses in an organic solvent (e.g., N-methylpyrrolidone). An organic solvent-based binder may be a binder that dissolves or disperses at a rate of 1 part by mass or more per 100 parts by mass of an organic solvent (e.g., N-methylpyrrolidone) at 20°C. When forming a positive electrode active material layer using a paste-like positive electrode mixture in which the dispersion medium is an organic solvent or a mixed solvent mainly composed of an organic solvent, an organic solvent-based binder (a polymer material having solubility or dispersibility in an organic solvent) can be used. Examples of organic solvent-based binders include polyvinylidene fluoride, copolymers of vinylidene fluoride and hexafluoropropylene, copolymers of ethylene and vinyl alcohol, polyacrylonitrile, polyphosphazene, polysiloxane, polyvinyl acetate, polymethyl methacrylate, polystyrene, polycarbonate, polyamide, polyimide, polyamideimide, crosslinked polymers of cellulose and chitosan pyrrolidone carboxylate, and derivatives of chitosan.

[0073] The binder may be a fluororesin (polytetrafluoroethylene, polyvinylidene fluoride, etc.), a polyolefin (polyethylene, polypropylene, etc.), an elastomer (ethylene propylene diene rubber, styrene butadiene rubber, fluororubber, etc.), a polysaccharide polymer (cellulose, chitosan derivatives, etc.), etc. One or more types of binders may be used.

[0074] The binder content in the positive electrode active material layer is preferably 0.1% by mass or more and 10% by mass or less, preferably 1% by mass or more and 9% by mass or less, and more preferably 3% by mass or more and 8% by mass or less. The upper limit of the binder content may be 5% by mass, 4% by mass, or 3% by mass. By setting the binder content within the above range, the positive electrode active material can be stably maintained. The technology disclosed herein can also be implemented in a form in which the positive electrode active material layer does not contain a binder.

[0075] Examples of thickening agents include polysaccharide polymers such as carboxymethylcellulose and methylcellulose. If the thickening agent has a functional group that reacts with lithium, etc., this functional group may be deactivated beforehand by methylation or the like. The thickening agent may also function as a binder. One or more types of thickening agents can be used. When the positive electrode active material layer contains a thickening agent, the content of the thickening agent in the positive electrode active material layer is preferably 0.1% by mass or more and 8% by mass or less, more preferably 5% by mass or less, and even more preferably 2% by mass or less. The technology disclosed herein can also be carried out in a form in which the positive electrode active material layer does not contain a thickening agent.

[0076] The filler is not particularly limited. The filler is a component other than the positive electrode active material, solid electrolyte, conductive agent, binder, and thickener, and may be a component that is intentionally included. The filler may be included as a component that fills gaps in the positive electrode active material layer, or it may be included for other purposes. The filler may be an organic substance such as a polyolefin, or an inorganic substance such as an inorganic oxide, hydroxide, or carbonate. One or more types of fillers can be used. When the positive electrode active material layer contains a filler, the filler content in the positive electrode active material layer can be 0.1% by mass or more and 8% by mass or less, usually preferably 5% by mass or less, and more preferably 2% by mass or less. The technology disclosed herein can also be carried out in a form in which the positive electrode active material layer does not contain a filler.

[0077] The positive electrode active material layer may further contain other components besides the positive electrode active material, solid electrolyte, conductive agent, binder, thickener, and filler. These other components may include those unintentionally present in the positive electrode active material layer. Furthermore, the positive electrode active material layer may contain impurities unintentionally present as these other components, insofar as they achieve the effects of the present invention. The upper limit of the content of these other components in the positive electrode active material layer may be 10% by mass, 5% by mass, 2% by mass, 1% by mass, 0.1% by mass, or 0.01% by mass. The upper limit of the content of unintentionally present components in the positive electrode active material layer may be 10% by mass, 5% by mass, 2% by mass, 1% by mass, 0.1% by mass, or 0.01% by mass. The upper limit of the content of unintentionally present impurities in the positive electrode active material layer may be 10% by mass, 5% by mass, 2% by mass, 1% by mass, 0.1% by mass, or 0.01% by mass.

[0078] The thickness of the positive electrode active material layer is set appropriately according to the type of positive electrode active material, the application of the all-solid-state energy storage element, etc. The average thickness of one positive electrode active material layer may be, for example, 5 μm or more and 1,000 μm or less. The lower limit of the average thickness of one positive electrode active material layer may be 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 100 μm, 120 μm, or 150 μm. The upper limit of the average thickness of one positive electrode active material layer may be 800 μm, 500 μm, 200 μm, 100 μm, 80 μm, 60 μm, or 40 μm. The mass per unit area of ​​one positive electrode active material layer may be, for example, 4 mg / cm². 2 More than 100mg / cm 2 The following is also acceptable: The lower limit of the mass per unit area of ​​one positive electrode active material layer is 6 mg / cm². 2 , 8 mg / cm³ 2 , 10 mg / cm³ 2 , 15 mg / cm³ 2 or 20 mg / cm³ 2 It may also be the case that the upper limit of the mass per unit area of ​​one positive electrode active material layer is 50 mg / cm². 2 , 20 mg / cm³ 2 , 15 mg / cm³ 2 , 12 mg / cm³ 2 or 10 mg / cm³2 That's fine.

[0079] (Negative electrode substrate) The negative electrode substrate has a substrate layer and a coating layer. The negative electrode substrate is typically connected to the negative electrode lead described above.

[0080] The base layer has a shape such as a sheet or plate. The base layer contains metallic aluminum. The metallic aluminum may be pure aluminum or an aluminum alloy. The content of metallic aluminum (pure aluminum and aluminum alloy) in the base layer is preferably 95% by mass or more, and more preferably 99% by mass or more. The content of aluminum element in the base layer is preferably 90% by mass or more, more preferably 95% by mass or more, and may be 99% by mass or more. An oxide film may be formed on the surface of the base layer. The base layer may be a foil. Pure aluminum foil or aluminum alloy foil can be used as the base layer. Examples of pure aluminum or aluminum alloy include A1085, A1N30, A3003, etc., as specified in JIS-H-4000 (2014) or JIS-H-4160 (2006).

[0081] The average thickness of the substrate layer may be, for example, 2 μm or more and 35 μm or less. The lower limit of the average thickness of the substrate layer may be 3 μm, 4 μm, 5 μm, or 10 μm. The upper limit of the average thickness of the substrate layer may be 30 μm, 20 μm, 15 μm, or 10 μm.

[0082] The coating layer is laminated over the entire surface of the substrate layer facing the negative electrode active material layer. The sides of the substrate layer are usually not covered by the coating layer, leaving the substrate layer exposed. The coating layer may or may not be laminated on the surface of the substrate layer opposite to the negative electrode active material layer.

[0083] The coating layer is electrically conductive. The coating layer contains a conductive agent. Examples of conductive agents contained in the coating layer include those similar to those exemplified as conductive agents in the positive electrode active material layer (carbon materials, metals, electrically conductive ceramics, etc.). Carbon materials are preferred as the conductive agent contained in the coating layer, and graphite or non-graphitic carbon is more preferred. Other conductive agents contained in the coating layer include metals that do not readily alloy with lithium, such as nickel, iron, chromium, cobalt, copper, or alloys thereof.

[0084] The lower limit of the conductive agent content in the coating layer is preferably 50% by mass, more preferably 60% by mass, even more preferably 70% by mass, and may be 80% by mass, 90% by mass, 95% by mass, 97% by mass, 99% by mass, or 100% by mass. The upper limit of the conductive agent content in the coating layer may be 100% by mass, and may be 99% by mass, 98% by mass, 97% by mass, 96% by mass, or 95% by mass.

[0085] The coating layer may be formed solely from a conductive agent. The coating layer may also be a layer of a metal that does not readily alloy with lithium, or an alloy of such a metal.

[0086] The coating layer may contain a binder along with the conductive agent. Examples of binders included in the coating layer are the same as those exemplified as the binder for the positive electrode active material layer.

[0087] The lower limit of the binder content in the coating layer is preferably 0% by mass, more preferably 1% by mass, and may be 2%, 3%, or 4% by mass. The upper limit of the binder content in the coating layer may be 10% by mass, 5%, or 3% by mass.

[0088] The coating layer may contain components other than the conductive agent and binder. However, the lower limit of the total content of the conductive agent and binder in the coating layer is preferably 95% by mass, more preferably 98% by mass, and even more preferably 99% by mass.

[0089] The lower limit of the average thickness of the coating layer is preferably 0.01 μm, more preferably 0.1 μm, and may also be 0.2 μm, 0.3 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, 5 μm, or 10 μm. Having an average thickness of the coating layer above this lower limit can further suppress the alloying reaction of the metallic aluminum in the base layer. The upper limit of the average thickness of the coating layer is preferably 20 μm, more preferably 15 μm, and may also be 10 μm, 5 μm, 3 μm, 2 μm, 1 μm, or 0.5 μm. Having an average thickness of the coating layer below this upper limit can make the all-solid-state energy storage element thinner. On the other hand, if the average thickness of the coating layer is below this upper limit, in conventional all-solid-state energy storage elements, the side surface of the base layer is more likely to come into contact with the negative electrode active material layer, etc., making the alloying reaction of the metallic aluminum in the base layer more likely to occur. Therefore, when one embodiment of the present invention is applied to an all-solid-state energy storage element in which the average thickness of the coating layer is less than or equal to the above upper limit, the advantage of sufficiently suppressing the alloying reaction of metallic aluminum in the base layer can be effectively obtained. Note that if the coating layer is laminated on both sides of the base layer, the average thickness of the coating layer shall be the average thickness of one coating layer.

[0090] The coating layer can be provided, for example, by coating with a coating layer-forming material containing a conductive agent and a dispersion medium. Alternatively, the coating layer can also be provided by vapor phase methods such as vacuum deposition and laser ablation, or by pressure molding.

[0091] (Negative electrode active material layer) The negative electrode active material layer has an operating potential of 0.5V (vs.Li / Li + Includes a negative electrode active material whose operating potential is 0.5V (vs.Li / Li). + A negative electrode active material that can be below 0.5V (vs.Li / Li) is a material whose normal charge-discharge reaction occurs in a potential range of 0.5V (vs.Li / Li). + This means that the negative electrode active material includes a range of 0.5V (vs.Li / Li). + The negative electrode active material may be such that the potential in the charged state is 0.5V (vs.Li / Li +The negative electrode active material may be less than or equal to 0.5V (vs.Li / Li) in some or all of the charge-discharge reactions during normal use of the all-solid-state energy storage element. + It may operate at a potential of 0.5V (vs.Li / Li) or less, and the entire charge-discharge reaction should be 0.5V (vs.Li / Li) + )It does not have to operate at a potential below this. Note that "normal use" means using the all-solid-state energy storage element by adopting the charge and discharge conditions recommended or specified for the all-solid-state energy storage element. For example, if equipment for using the all-solid-state energy storage element is available, the all-solid-state energy storage element may be used by applying that equipment. The negative electrode active material layer may contain optional components such as a solid electrolyte, conductive agent, binder, thickener, and filler as needed. Optional components such as a solid electrolyte, conductive agent, binder, thickener, and filler can be selected from the materials exemplified above for the positive electrode. The negative electrode active material layer may be formed from a negative electrode mixture containing a negative electrode active material and other optional components.

[0092] The negative electrode active material has an operating potential of 0.5V (vs.Li / Li + Known negative electrode active materials that can have an operating potential of 0.5V (vs.Li / Li) or less can be used. For negative electrode active materials in all-solid-state energy storage devices that use lithium ions as charge transport ions, materials that can intercept and release lithium ions are usually used. + Examples of negative electrode active materials that can have an operating potential of 0.5V (vs.Li / Li) include metallic lithium; metals or metalloids such as silicon and tin; metal oxides or metalloid oxides such as silicon oxide and tin oxide; silicon carbide; and carbon materials such as graphite and non-graphitic carbon. + As a negative electrode active material that can have an operating potential of 0.5V (vs.Li / Li), carbon materials are preferred, and graphite is more preferred. The graphite may have its surface coated with other materials such as non-graphite carbon. One or more negative electrode active materials can be used. As a negative electrode active material, an operating potential of 0.5V (vs.Li / Li) is preferred. + Only negative electrode active materials that can be less than or equal to 0.5V (vs.Li / Li) may be used, and the operating potential is 0.5V (vs.Li / Li + The negative electrode active material and the operating potential which can be less than or equal to 0.5V (vs. Li / Li+ It may also be used in combination with a negative electrode active material that does not fall below )

[0093] "Graphite" refers to the average lattice plane spacing (d) of the (002) plane, determined by X-ray diffraction before charging or discharging, or during the discharge state. 002 This refers to carbon materials with a n-scale between 0.33 nm and less than 0.34 nm. Examples of graphite include natural graphite and artificial graphite.

[0094] "Non-graphite carbon" refers to the average lattice plane spacing (d) of the (002) plane, which is determined by X-ray diffraction before charging / discharging or during the discharge state. 002 ) refers to carbon materials with a nautical index of 0.34 nm to 0.42 nm. Non-graphitic carbons include poorly graphitizable carbons and easily graphitizable carbons. "Potentially graphitizable carbon" refers to the above d 002 This refers to carbon materials with a wavelength of 0.36 nm or more and 0.42 nm or less. "Easily graphitizable carbon" refers to the above d 002 This refers to carbon materials with a wavelength of 0.34 nm or more and less than 0.36 nm.

[0095] Here, the "discharge state" of the carbon material refers to a state in which sufficient lithium ions that can be absorbed and released during charging and discharging are released from the carbon material, which is the negative electrode active material. For example, in a half-cell using a negative electrode containing a carbon material as the negative electrode active material as the working electrode and metallic lithium as the counter electrode, this is a state in which the open-circuit voltage is 0.7V or higher.

[0096] The negative electrode active material may be in particulate form. The average particle size of the negative electrode active material can be, for example, 1 nm to 100 μm. If the negative electrode active material is a carbon material, its average particle size may be 1 μm to 100 μm. If the negative electrode active material is Si, Sn, Si oxide, or Sn oxide, its average particle size may be 1 nm to 1 μm. Setting the average particle size of the negative electrode active material above the lower limit makes it easier to manufacture or handle. Setting the average particle size of the negative electrode active material below the upper limit improves the electronic conductivity of the negative electrode active material layer.

[0097] The content of the negative electrode active material in the negative electrode active material layer is preferably, for example, 60% to 99% by mass, and more preferably 90% to 98% by mass. By setting the content of the negative electrode active material within the above range, it is possible to achieve both high energy density and manufacturability in the negative electrode active material layer.

[0098] When the negative electrode active material is a metal such as metallic lithium, the negative electrode active material layer may be in the form of foil. The metallic lithium may exist as pure metallic lithium consisting substantially of the element lithium alone, or as a lithium alloy containing other metallic elements. When the negative electrode active material is a metal such as metallic lithium, the lithium element content in the negative electrode active material layer may be 90% by mass or more, 99% by mass or more, or 100% by mass.

[0099] When the negative electrode active material layer contains a conductive agent, the content of the conductive agent in the negative electrode active material layer is preferably 1% by mass or more and 10% by mass or less, and more preferably 3% by mass or more and 9% by mass or less. The content of the conductive agent in the negative electrode active material layer may be 5% by mass or less, or 2% by mass or less. The technology disclosed herein can also be carried out in a form in which the negative electrode active material layer does not contain a conductive agent.

[0100] If the negative electrode active material layer contains a solid electrolyte, the solid electrolyte content is preferably 5% by mass or more and 90% by mass or less, but may also be 10% by mass or more and 70% by mass or less, or 20% by mass or more and 50% by mass or less.

[0101] When the negative electrode active material layer contains a binder, the binder content in the negative electrode active material layer is preferably 0.1% by mass or more and 10% by mass or less, and more preferably 0.5% by mass or more and 8% by mass or less. The binder content in the negative electrode active material layer may be 5% by mass or less, or 2% by mass or less. The technology disclosed herein can also be carried out in a form in which the negative electrode active material layer does not contain a binder.

[0102] When the negative electrode active material layer contains a thickening agent, the content of the thickening agent in the negative electrode active material layer is preferably 0.1% by mass or more and 10% by mass or less, and more preferably 0.5% by mass or more and 8% by mass or less. The content of the thickening agent in the negative electrode active material layer may be 5% by mass or less, or 2% by mass or less. The technology disclosed herein can also be carried out in a form in which the negative electrode active material layer does not contain a thickening agent.

[0103] The filler in the negative electrode active material layer is a component other than the negative electrode active material, solid electrolyte, conductive agent, binder, and thickener, and may be a component that is intentionally included. The filler may be included as a component that fills gaps in the negative electrode active material layer, or it may be included for other purposes. When the negative electrode active material layer contains a filler, the filler content in the negative electrode active material layer can be 0.1% by mass or more and 8% by mass or less, usually preferably 5% by mass or less, and more preferably 2% by mass or less. The technology disclosed herein can also be carried out in a form in which the negative electrode active material layer does not contain a filler.

[0104] The negative electrode active material layer may further contain other components besides the negative electrode active material, solid electrolyte, conductive agent, binder, thickener, and filler. These other components may include those unintentionally present in the negative electrode active material layer. Furthermore, the negative electrode active material layer may contain impurities unintentionally present as these other components, insofar as they achieve the effects of the present invention. The upper limit of the content of these other components in the negative electrode active material layer may be 10% by mass, 5%, 2%, 1%, 0.1%, or 0.01% by mass. The upper limit of the content of unintentionally present components in the negative electrode active material layer may be 10% by mass, 5%, 2%, 1%, 0.1%, or 0.01% by mass. The upper limit of the content of unintentionally present impurities in the negative electrode active material layer may be 10% by mass, 5%, 2%, 1%, 0.1%, or 0.01% by mass.

[0105] The thickness of the negative electrode active material layer is set appropriately according to the type of negative electrode active material, the application of the all-solid-state energy storage element, etc. The average thickness of one negative electrode active material layer may be, for example, 5 μm or more and 1,000 μm or less. The lower limit of the average thickness of one negative electrode active material layer may be 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 100 μm, 150 μm, or 200 μm. The upper limit of the average thickness of one negative electrode active material layer may be 800 μm, 500 μm, 200 μm, 100 μm, 80 μm, 60 μm, or 40 μm. The mass per unit area of ​​one negative electrode active material layer may be, for example, 2 mg / cm². 2 More than 50mg / cm 2 The following is also acceptable: The lower limit of the mass per unit area of ​​one negative electrode active material layer is 3 mg / cm². 2 , 4 mg / cm³ 2 , 5 mg / cm³ 2 , 6 mg / cm³ 2 , 10 mg / cm³ 2 or 15 mg / cm³ 2 It may also be the case that the upper limit of the mass per unit area of ​​one negative electrode active material layer is 30 mg / cm³. 2 , 20 mg / cm³ 2 , 15 mg / cm³ 2 , 12 mg / cm³ 2 or 10 mg / cm³ 2 That's fine.

[0106] (solid electrolyte layer) The solid electrolyte layer contains a solid electrolyte. The solid electrolyte used in the solid electrolyte layer may be an inorganic solid electrolyte or another solid electrolyte, but it is preferably an inorganic solid electrolyte, and more preferably a sulfide-based solid electrolyte. The solid electrolyte can be selected from the materials exemplified in the positive electrode active material layer. The solid electrolyte content in the solid electrolyte layer is preferably 70% by mass or more and 100% by mass or less. The solid electrolyte content in the solid electrolyte layer may be 90% by mass or more, 99% by mass or more, or 100% by mass.

[0107] The solid electrolyte layer may contain optional components such as additives (e.g., phosphoric acid compounds such as Li3PO4, oxides, halogen compounds), binders, thickeners, and fillers. These optional components can be selected from the materials exemplified in the positive electrode active material layer.

[0108] The average thickness of the solid electrolyte layer is preferably 1 μm to 100 μm, more preferably 2 μm to 50 μm, and even more preferably 3 μm to 20 μm. By setting the average thickness of the solid electrolyte layer to above the lower limit, it becomes possible to reliably insulate the positive electrode and the negative electrode. By setting the average thickness of the solid electrolyte layer to below the upper limit, it becomes possible to increase the energy density of the all-solid-state energy storage element.

[0109] (Materials that do not possess ionic conductivity) As a component that does not have ionic conductivity, it can be appropriately selected and used from materials that do not have ionic conductivity, such as resins, carbon materials, metals, and metal oxides. Resins are preferred as components that do not have ionic conductivity from the viewpoint of moldability, etc. Components that do not have ionic conductivity do not necessarily have to have electronic conductivity, and it is preferable that they do not have electronic conductivity.

[0110] Resins used as components that do not have ionic conductivity include polyolefins (polyethylene, polypropylene, etc.), fluororesins (polytetrafluoroethylene, polyvinylidene fluoride, etc.), elastomers (ethylene propylene diene rubber, styrene butadiene rubber, fluororubber, etc.), polyimides, polyamides (nylon, aramid, etc.), polyacrylonitrile, polysiloxane, polystyrene, polycarbonate, polyester, and the like. Resins used as components that do not have ionic conductivity may be thermoplastic resins or thermosetting resins. Resins used as components that do not have ionic conductivity may also be heat-meltable resins.

[0111] Non-ionic conductive members may also be those containing other components (e.g., inorganic particles) along with the resin. Non-ionic conductive members may or may not be porous. In one embodiment of the present invention, it is preferable that the non-ionic conductive member is not porous (i.e., a member without voids).

[0112] Examples of ion-conducting components include the aforementioned layers containing the solid electrolyte (negative electrode active material layer, solid electrolyte layer, etc.).

[0113] (container) The container houses the positive electrode, negative electrode, etc., within its internal space. The container material can be a metal material such as aluminum or stainless steel, or a resin material; metal materials are preferred from the viewpoint of strength, etc. Composite materials of metal and resin materials can also be used.

[0114] The shape of the container is not particularly limited, but it can be cylindrical, rectangular (square), disc-shaped, etc. The container may also be in the form of a sheet or other shape formed from a metal-resin composite film.

[0115] (Shape, application, etc. of all-solid-state energy storage elements) The shape of the all-solid-state energy storage element according to one embodiment of the present invention is not particularly limited. The all-solid-state energy storage element may be, for example, a cylindrical battery, a prismatic battery, a flat battery, a coin cell battery, a button cell battery, etc.

[0116] The applications of the all-solid-state energy storage element according to one embodiment of the present invention are not particularly limited. The all-solid-state energy storage element can be used, for example, as a power source for automobiles such as electric vehicles, hybrid vehicles, and plug-in hybrid vehicles, as a power source for electronic devices such as personal computers and communication terminals, and as a power storage power source.

[0117] The all-solid-state energy storage element of the present invention can be used individually or in combination. When the required output and voltage are small, the all-solid-state energy storage element may be used individually. On the other hand, when at least one of the required output and voltage is large, the all-solid-state energy storage element may be used in a storage device combined with other all-solid-state energy storage elements. In a storage device composed of multiple all-solid-state energy storage elements, at least one of the all-solid-state energy storage elements included in the storage device may be an all-solid-state energy storage element according to one embodiment of the present invention. The storage device will be described in detail later.

[0118] In the all-solid-state energy storage element according to one embodiment of the present invention, the container may be restrained to maintain a certain thickness, or it may not be restrained in such a way. Alternatively, the container may be restrained to have a certain load applied to it. When the container is restrained, expansion of the container due to charge-discharge cycles, etc., may be suppressed, and a decrease in charge-discharge performance may be suppressed. When the container is restrained, the positive and negative electrodes inside the container may or may not have a load applied to them. For example, the all-solid-state energy storage element or energy storage device may be provided with a restraining member that performs such restraint.

[0119] <Manufacturing method for all-solid-state energy storage elements> The method for manufacturing an all-solid-state energy storage element according to one embodiment of the present invention is not particularly limited, but an example of a method for manufacturing the all-solid-state energy storage element 1 shown in Figure 1 will be described below with reference to Figures 9A to 9C.

[0120] A negative electrode substrate 11 is prepared by laminating a coating layer 17 on one side of a base layer 16 containing metallic aluminum. The negative electrode substrate 11 may be a commercially available product, or it may be made by applying a coating layer 17 to the base layer 16 by coating or the like. A negative electrode active material layer 12 is placed on the central part 18 of the negative electrode substrate 11 on the side where the coating layer 17 is laminated to obtain a negative electrode 21 (see Figure 9A). The placement of the negative electrode active material layer 12 can be done, for example, by coating a paste-like negative electrode mixture. When coating a paste-like negative electrode mixture, for example, the coating can be performed with the negative electrode substrate 11 masked, and the mask can be removed after coating to provide a negative electrode active material layer 12 of a predetermined shape. After coating the paste-like negative electrode mixture, the dispersion medium contained in the paste-like negative electrode mixture may be dried and removed. The placement of the negative electrode active material layer 12 can also be done by transferring a negative electrode active material layer 12 that has been pre-formed into a predetermined shape onto the negative electrode substrate 11.

[0121] Next, a non-ionic conductive member 20, which has been pre-formed into a frame shape, is placed on the peripheral edge 19 of the negative electrode substrate 11 on the side where the coating layer 17 is provided, so as to surround the side surface of the negative electrode active material layer 12 (see Figure 9B). The non-ionic conductive member 20 may also be placed on the peripheral edge 19 of the negative electrode substrate 11 on the side where the coating layer 17 is provided by coating or the like. Next, a solid electrolyte layer 13 is placed on the negative electrode active material layer 12 and the non-ionic conductive member 20 by transfer, coating or the like to obtain a negative electrode laminate 22 (see Figure 9B).

[0122] On the other hand, a positive electrode active material layer 14 is placed on the positive electrode substrate 15 to obtain a positive electrode 23. The positive electrode active material layer 14 can be placed, for example, by coating with a paste-like positive electrode mixture. After coating with the paste-like positive electrode mixture, the dispersion medium contained in the paste-like positive electrode mixture may be dried and removed. The positive electrode active material layer 14 can also be placed by transferring a positive electrode active material layer 14, which has been pre-formed into a predetermined shape, onto the positive electrode substrate 15.

[0123] The obtained negative electrode laminate 22 and positive electrode 23 are stacked so that the negative electrode active material layer 12 and positive electrode active material layer 14 face each other via the solid electrolyte layer 13, and then heated and pressed to obtain the electrode body with the laminated structure shown in Figure 1 (see Figure 9C).

[0124] After obtaining the electrode body, the all-solid-state energy storage element can be completed by conventionally known methods, such as housing the electrode body in a container.

[0125] <Energy storage device> The energy storage device 70 in Figure 10 comprises a plurality of energy storage units 60. Each energy storage unit 60 comprises a plurality of electrically connected solid-state energy storage elements 10. The energy storage device 70 may also include busbars (not shown) for electrically connecting the plurality of solid-state energy storage elements 10, busbars (not shown) for electrically connecting the plurality of energy storage units 60, etc. The energy storage unit 60 or the energy storage device 70 may also include a condition monitoring device (not shown) for monitoring the state of one or more solid-state energy storage elements 10.

[0126] <Other Embodiments> The all-solid-state energy storage element of the present invention is not limited to the embodiments described above, and various modifications may be made without departing from the spirit of the invention. For example, the configuration of one embodiment may be added to the configuration of another embodiment, and a part of the configuration of one embodiment may be replaced with the configuration of another embodiment or with well-known technology. Furthermore, a part of the configuration of one embodiment may be deleted. Also, well-known technology may be added to the configuration of one embodiment.

[0127] In the above embodiment, a case in which the all-solid-state energy storage element is used as a rechargeable non-aqueous electrolyte secondary battery was described, but the type, shape, dimensions, capacity, etc. of the all-solid-state energy storage element are arbitrary. The present invention can also be applied to various secondary batteries, electric double-layer capacitors, lithium-ion capacitors, and other capacitors.

[0128] For example, the all-solid-state energy storage element according to the present invention may include layers other than the positive electrode, solid electrolyte layer, and negative electrode. The present invention can also be applied to all-solid-state energy storage elements that include bipolar electrodes.

[0129] <Examples> The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0130] [Example 1] A 2.5 cm × 2.5 cm square-shaped negative electrode substrate was prepared, with a coating layer (carbon coating layer) with an average thickness of 0.3 μm containing carbon material as a conductive agent on the surface of an aluminum foil base layer. A 2.0 cm × 2.0 cm square-shaped negative electrode active material layer was placed on the center of the negative electrode substrate on the side with the coating layer. The negative electrode active material layer was made from a negative electrode mixture consisting of negative electrode active material (graphite), sulfide solid electrolyte, binder, thickener, and dispersion medium, and the dispersion medium was dried and removed. The mass per unit area of ​​the negative electrode active material layer was 21 mg / cm². 2 The average thickness was set to 300 μm. Next, a non-ionic conductive member, pre-formed into a frame shape, was placed on the peripheral edge of the negative electrode substrate on the side where the coating layer was provided, so as to surround the side surface of the negative electrode active material layer. The non-ionic conductive member was made from a polyamide resin film, which is a heat-meltable resin. The average thickness of the non-ionic conductive member after heating and pressing (400 MPa, 160°C, 1 minute) was set to be the same as the average thickness of the negative electrode active material layer. Next, a solid electrolyte layer containing an argyrodite-type sulfide solid electrolyte, measuring 2.3 cm × 2.3 cm in plan view as a square, was placed on the negative electrode active material layer and the non-ionic conductive member by transfer to obtain the negative electrode side laminate. A positive electrode was obtained by placing a 2.0 cm x 2.0 cm square-shaped positive electrode active material layer on the surface of a 2.0 cm x 2.0 cm square-shaped aluminum foil, which served as the positive electrode substrate. The positive electrode active material layer contained the positive electrode active material (LiNi x Co y Mn 1-X-YThe positive electrode mixture was formed from a lithium transition metal composite oxide (represented by O2), a sulfide solid electrolyte, a conductive agent (fibrous graphite), a binder, a thickener, and a dispersion medium, and the dispersion medium was dried and removed. The mass per unit area of ​​the positive electrode active material layer was 22.5 mg / cm². 2 The average thickness was set at 180 μm. The obtained negative electrode laminate and positive electrode were stacked so that the negative electrode active material layer and the positive electrode active material layer faced each other via the solid electrolyte layer, and then heated and pressed (400 MPa, 160°C, 1 minute) to obtain the electrode body with the laminated structure shown in Figure 1. Using the obtained electrode body, the all-solid-state energy storage element of Example 1 was completed.

[0131] [Comparative Example 1] A 2.1 cm × 2.1 cm square-shaped negative electrode substrate was prepared, with a coating layer (carbon coating layer) with an average thickness of 0.3 μm containing carbon material as a conductive agent on the surface of an aluminum foil base layer. A 2.1 cm × 2.1 cm square-shaped negative electrode active material layer was placed on the negative electrode substrate on the side with the coating layer. The negative electrode active material layer was made from the same negative electrode mixture as in Example 1, with the dispersion medium dried and removed. The mass per unit area of ​​the negative electrode active material layer was 21 mg / cm². 2 The average thickness was set to 300 μm. Next, a solid electrolyte layer containing an argyrodite-type sulfide solid electrolyte, measuring 2.1 cm × 2.1 cm in plan view and square in shape, was placed on the negative electrode active material layer by transfer to obtain the negative electrode laminate. A positive electrode was obtained by placing a 2.0 cm × 2.0 cm square-shaped positive electrode active material layer on the surface of a 2.0 cm × 2.0 cm square-shaped aluminum foil, which served as the positive electrode substrate. The positive electrode active material layer was made from the same positive electrode mixture as in Example 1, and the dispersion medium was dried and removed. The mass per unit area of ​​the positive electrode active material layer was 22.5 mg / cm². 2 The average thickness was set at 180 μm. The obtained negative electrode laminate and positive electrode were stacked so that the negative electrode active material layer and positive electrode active material layer faced each other via a solid electrolyte layer, and then heated and pressed (400 MPa, 160°C, 1 minute) to obtain the electrode body with the laminated structure shown in Figure 11. Using the obtained electrode body, the all-solid-state energy storage element of Comparative Example 1 was completed. In the all-solid-state energy storage element of Comparative Example 1, the negative electrode active material layer 12, which is an ion-conductive material, is arranged on the peripheral edge 19 of the surface of the negative electrode substrate 11 facing the negative electrode active material layer 12 (see Figure 11).

[0132] (Charge / Discharge Test) Charge and discharge tests were performed on each of the all-solid-state energy storage elements in Example 1 and Comparative Example 1 at a temperature of 50°C in the following manner. Constant current and constant voltage charging was performed with a charging current of 0.1C and a charging termination voltage of 4.25V. The charging termination condition was when the charging current became 0.025C. Subsequently, constant current discharge was performed with a discharge current of 0.1C and a discharge termination voltage of 2.85V. A 10-minute rest period was provided after both charging and discharging. This charge-discharge cycle was performed twice. The Coulomb efficiency (the percentage of discharged electricity in the second cycle relative to the charged electricity in the second cycle) for each all-solid-state energy storage element was determined. The Coulomb efficiency of the all-solid-state energy storage element in Example 1 was 99.0%. On the other hand, the Coulomb efficiency of the all-solid-state energy storage element in Comparative Example 1 was 83.9%.

[0133] The all-solid-state energy storage element in Comparative Example 1, which had the stacked structure shown in Figure 11, exhibited low Coulomb efficiency, while the all-solid-state energy storage element in Example 1, which had the stacked structure shown in Figure 1, exhibited high Coulomb efficiency. In the all-solid-state energy storage element in Comparative Example 1, it is thought that the contact between the side surface of the substrate layer and the negative electrode active material layer caused an alloying reaction of the metallic aluminum in the substrate layer, resulting in low Coulomb efficiency. On the other hand, in the all-solid-state energy storage element in Example 1, the stacked structure shown in Figure 1 suppressed contact between the side surface of the substrate layer and the negative electrode active material layer and the solid electrolyte layer, thus sufficiently suppressing the alloying reaction of the metallic aluminum in the substrate layer and resulting in high Coulomb efficiency. [Industrial applicability]

[0134] This invention can be applied to all-solid-state energy storage elements used as power sources for electronic devices such as personal computers and communication terminals, and for automobiles, etc. [Explanation of symbols]

[0135] 1, 2, 3, 4, 5, 6, 7, 8, 10 All-solid-state energy storage elements 11. Negative electrode substrate 12 Negative electrode active material layer 13 Solid electrolyte layer 14 Cathode active material layer 15 Positive electrode substrate 16 Base material layer 17 Covering layer 18 Central part 19 Periphery 20. Components that do not possess ionic conductivity 21 Negative electrode 22 Negative electrode laminate 23 Positive electrode 60 Energy Storage Units 70 Energy storage devices

Claims

1. Using lithium ions as charge transport ions, It has a laminated structure comprising a negative electrode substrate, a negative electrode active material layer, and a solid electrolyte layer in this order. The above-mentioned negative electrode substrate comprises a substrate layer containing metallic aluminum, and a coating layer having electronic conductivity which is laminated over the entire surface of the substrate layer on the side facing the negative electrode active material layer. The above negative electrode active material layer has an operating potential of 0.5V (vs. Li / Li ＋ ) Contains a negative electrode active material which may be less than or equal to, In the negative electrode substrate, no ion-conducting member is provided at the peripheral edge of the surface on the negative electrode active material layer side, or An all-solid-state energy storage element in which the side surface of the above-mentioned base material layer is covered with a member A that does not have ion conductivity.

2. The all-solid-state energy storage element according to claim 1, wherein at least a portion of the peripheral edge of the surface of the negative electrode substrate on the negative electrode active material layer side is provided with a member B that does not have ion conductivity.

3. The all-solid-state energy storage element according to claim 1 or claim 2, wherein at least a portion of the peripheral edge of the surface on the negative electrode active material layer side of the negative electrode substrate is exposed.

4. The all-solid-state energy storage element according to claim 1 or claim 2, wherein the average thickness of the coating layer is 0.01 μm or more and 20 μm or less.

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