JP7272788B2 - Method for manufacturing all-solid-state battery - Google Patents

Description

The present disclosure relates to a method for manufacturing an all-solid-state battery.

In recent years, all-solid-state batteries have been proposed as power sources for mobile devices, automobiles, and the like.

In all-solid-state batteries using a solid electrolyte as an electrolyte, generally, in order to maintain contact between the active material and the solid electrolyte, etc., a restraining force is applied in the stacking direction of each layer constituting the all-solid-state battery.

In addition, in order to improve the durability of the all-solid-state battery, immediately after manufacturing the all-solid-state battery and before the actual use, the all-solid-state battery is charged to an initial charging voltage higher than the charging and discharging voltage during actual use. It has been proposed to perform an initial charging step of charging the

Various developments have been made on all-solid-state batteries, including such restraint and initial charging of all-solid-state batteries.

For example, in Patent Document 1, the restrained body is provided with length adjusting means for converging variations in the length L1 in the stacking direction, and by setting the length adjusting means according to the length L1, the assembled battery is a prescribed length LT in the stacking direction and the binding pressure of the object to be bound is a prescribed pressure P.

Patent Literature 2 discloses a flat secondary battery restraining device that restrains a plurality of flat secondary batteries stacked in a planar direction. More specifically, a frame for mounting a plurality of stacked flat secondary batteries, a plate spacer for partitioning adjacent flat secondary batteries, and a plurality of stacked flat secondary batteries in the stacking direction. A constraining device for a flat secondary battery comprising a pressing plate for pressing and a pressing member for applying pressure to the pressing plate, wherein the plate-like spacer has a plate-like silicone rubber cushioning member, and the pressing is a constant pressure press. is disclosed.

Patent Literature 3 discloses a method for manufacturing an all-solid-state battery system, which includes an initial charging step of charging the all-solid-state battery to an initial charging voltage higher than the charging/discharging voltage. Further, Patent Document 3 discloses performing performance evaluation while restraining a manufactured all-solid-state battery with a restraining jig under a restraining pressure of 2 N·m.

Patent Document 4 discloses an all-solid-state lithium ion battery comprising a laminate of a positive electrode, a Si negative electrode, and a solid electrolyte layer, and a restraining member that applies a restraining pressure to the laminate. An all-solid-state lithium-ion battery having a confining pressure of 0.1 MPa or more and 45 MPa or less is disclosed.

Patent Literature 5 discloses a method of injecting an electrolytic solution into an electricity storage module, which includes a constraint step of constraining the electricity storage module in the stacking direction at a constant pressure or a constant size.

JP 2009-200051 A JP 2015-022817 A JP 2017-059534 A JP 2018-106984 A JP 2018-106850 A

When the all-solid-state battery is charged and discharged, the active material layer (especially the negative electrode active material layer) expands and contracts. On the other hand, as a method of constraining an all-solid-state battery, there is a constant-size constraint that constrains the all-solid-state battery so that the size of the all-solid-state battery is substantially constant even when the active material layer expands and contracts, and the Constant pressure constraint is known, which constrains the all-solid-state battery so that the pressure that constrains the all-solid-state battery becomes substantially constant when contracted.

Of these, fixed-size restraint has the advantage that the device for restraint can have a simple configuration, but the restraint pressure applied to the all-solid-state battery when filled becomes excessively large, and the active material layer swells as a result. As such, other active material layers and/or solid electrolyte layers may be damaged.

On the other hand, constant pressure restraint has the advantage of preventing the restraint pressure applied to the all-solid-state battery from becoming excessively large when it is filled, but the equipment for restraint is relatively complicated and large. There is a problem that the energy density of the all-solid-state battery including the restraint device becomes small.

Therefore, the present disclosure has been made in view of the above circumstances, and a method for manufacturing an all-solid-state battery that can both suppress damage to the active material layer constituting the all-solid-state battery and improve the energy density of the all-solid-state battery. intended to provide

The inventors of the present disclosure have found that the above problems can be solved by a method for manufacturing an all-solid-state battery including the following steps (a) to (c):
(a) Providing a battery laminate having at least one unit battery configured by laminating a positive electrode current collector layer, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector layer in this order. to do
(b) charging the battery stack at an initial charging voltage while constraining the stack to a constant pressure in the stacking direction of the layers constituting the unit battery; and (c) making the battery stack constitute the unit battery. Constrain to a fixed size in the stacking direction of the layers.

According to the method for manufacturing an all-solid-state battery of the present disclosure, it is possible to both suppress deterioration of the all-solid-state battery and improve the energy density of the all-solid-state battery.

FIG. 1 is a conceptual diagram showing one aspect of a constant pressure/constant dimension restraint mechanism used in the method of the present disclosure. FIG. 2 is a schematic cross-sectional view showing one aspect of a unit battery according to the present disclosure. FIG. 3 is a conceptual diagram showing one mode when the fixed-dimension restraint mechanism is removed from the constant-pressure restraint mechanism.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this disclosure is demonstrated in detail, referring drawings. For convenience of explanation, the same reference numerals are given to the same or corresponding parts in each drawing, and duplicate explanations will be omitted. Not all components of the embodiments are essential, and some components may be omitted. However, the forms shown in the following figures are examples of the present disclosure and do not limit the present disclosure.

<<Method for manufacturing all-solid-state battery>>
The method for manufacturing an all-solid-state battery of the present disclosure includes the following steps (a) to (c):
(a) Providing a battery laminate having at least one unit battery configured by laminating a positive electrode current collector layer, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector layer in this order. to do
(b) charging the battery stack at the initial charging voltage while constraining the battery stack to a constant pressure in the stacking direction of the layers that make up the unit battery; and (c) charging the battery stack in the stacking direction of the layers that make up the unit battery. In the above, it shall be constrained to a fixed size.

In the present disclosure, the “stacking direction of the layers that make up the unit battery” means the direction in which the layers that make up the unit battery are stacked, that is, the direction perpendicular to the surface direction of the unit battery or each layer that makes up the unit battery. point to

According to the method of the present disclosure for manufacturing an all-solid-state battery, it is possible to both suppress breakage of the active material layer and the like constituting the all-solid-state battery and improve the energy density and the like of the all-solid-state battery. Without being limited to theory, it is believed that the expansion and contraction of the active material layer during initial charging is greater than the expansion and contraction of the active material layer during actual use of the battery. If the all-solid-state battery is constrained at a constant pressure to prevent the constraining pressure applied to the all-solid-state battery from becoming excessively large during the initial charging, then the all-solid-state battery can be constrained at a constant size during actual use. This is thought to be due to the fact that damage to the active material layer or the like due to excessive confining pressure can be suppressed.

The method of the present disclosure can fabricate an all-solid-state battery using, for example, one embodiment of the constant pressure, constant dimension restraint mechanism shown in FIG.

FIG. 1(a) is a schematic side view of a constant pressure and constant dimension restraint mechanism. This constant pressure/constant size restraint mechanism includes a constant pressure presser 10, a restraint plate 11, and restraint jigs 12 and 13. A constant pressure restraint mechanism includes constant size bars 20 and 21, restraint plates 22 and 23, and screws 24-31. and each of these mechanisms can be separated. FIG. 1(a-1) is a conceptual front view of the constant pressure restraint mechanism viewed from the side, and FIG. 1(a-2) is a conceptual front view of the fixed length restraint mechanism viewed from the side.

Therefore, when performing the step (b) according to the present disclosure, only the constant pressure constraint mechanism works, and the battery stack 5 having the unit batteries 1 to 4 is constrained at a constant pressure in accordance with the expansion of the active material layer. Cracks and deformation resulting from expansion of the active material layer can be suppressed, and as a result, deterioration of the all-solid-state battery can be suppressed.

Further, when the step (c) according to the present disclosure is performed, the constant pressure restraint mechanism and the constant dimension restraint mechanism are separated from each other, and only the constant dimension restraint mechanism works to constrain the battery stack 5 to a constant dimension. resistance can be reduced. By separating the constant pressure restraint mechanism, the energy density of the all-solid-state battery can be improved.

Details of each step will be described below.

<Step (a)>
In the step (a), a battery stack having at least one unit battery configured by stacking a positive electrode current collector layer, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector layer in this order. provide the body

A battery stack constituting an all-solid-state battery of the present disclosure has one or more unit cells.

For example, the battery stack 5 shown in FIG. 1(a) has four unit batteries 1-4.

Here, the unit battery is configured by laminating a positive electrode current collector layer, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector layer in this order.

FIG. 2 is a schematic cross-sectional view showing one aspect of a unit battery according to the present disclosure. As shown in FIG. 2, the unit battery 1 includes a positive electrode current collector layer 1a, a positive electrode active material layer 1b, a solid electrolyte layer 1c, a negative electrode active material layer 1d, and a negative electrode current collector layer 1e in this order. It is constructed by stacking.

In the unit battery, the positive electrode current collector layer may have a positive electrode current collector projecting portion projecting in the surface direction, and the positive electrode current collector tab is electrically connected to the positive electrode current collector projecting portion. It can be. Similarly, the negative electrode current collector layer may have a negative electrode current collector protrusion, and a negative electrode current collector tab may be electrically connected to the negative electrode current collector protrusion. Electric power generated in the all-solid-state battery stack can be taken out to the outside through the current collector protrusions and current collection tabs of each pole. When the battery stack has a plurality of positive electrode or negative electrode current collector layers, the plurality of current collector protrusions of each electrode are electrically connected to each other, and then the current collector tabs of each electrode are connected to each other. can be electrically connected to

For example, in FIG. 1(a-2), the unit battery 4 has collector tabs 4f and 4g electrically connected to the positive and negative collector layers. In FIG. 1(a), one of the current collecting tabs 1f to 4f of each of the unit batteries 1 to 4 can be confirmed.

When the battery stack has two or more unit cells, it may be a bipolar battery stack or a monopolar stack. Also, two unit batteries adjacent to each other in the stacking direction may share a positive/negative collector layer that is used as both the positive and negative collector layers. Furthermore, in both the bipolar type and monopolar type battery stacks, the current collector layer positioned as the outermost layer in the stacking direction may be the same electrode or different electrodes.

The method of providing a battery stack having one or more unit cells is not particularly limited. Alternatively, the negative electrode active material layer, the solid electrolyte layer and the positive electrode active material layer are laminated to form a three-layer laminate, and the three-layer laminate and the current collector layer are further laminated, A battery laminate may be formed, or each layer constituting a unit battery may be laminated to form a unit battery, and each unit battery may be laminated to form a battery laminate.

Moreover, the active material layer and the solid electrolyte layer that constitute the unit battery can be formed by compacting (press molding) respective constituent materials.

For example, a positive electrode active material and a constituent material containing additives used in the positive electrode active material layer of an all-solid-state battery such as a solid electrolyte, a conductive aid, and a binder used as necessary are subjected to powder compaction. An active material layer can be formed. In addition, by compacting a constituent material containing the negative electrode active material and additives used in the negative electrode active material layer of the all-solid battery such as a solid electrolyte, a conductive aid, and a binder used as necessary, the negative electrode An active material layer can be formed. Alternatively, a solid electrolyte layer may be formed by compacting a constituent material containing a solid electrolyte and additives used in the solid electrolyte layer of an all-solid-state battery, such as a conductive aid and a binder, which are used as necessary. can be done.

The shape of the battery stack is not particularly limited, and may be, for example, a coin shape, a laminate shape, a cylindrical shape, a square shape, or the like.

<Step (b)>
In step (b), the battery stack is charged at an initial charging voltage while being constrained to a constant pressure in the stacking direction of the layers constituting the unit battery.

For example, step (b) and step (c), which will be described later, can be continuously performed using the constant-pressure/constant-dimension restraint mechanism shown in FIG. 1(a). That is, the battery stack 5 having the unit cells 1 to 4 is set in the sizing constraining mechanism, is set in the constant pressure constraining mechanism, and the step (b) is first performed in a state where the sizing constraining mechanism does not function, Then, step (c) can be performed in a state in which the constant size restraint mechanism is removed from the constant pressure restraint mechanism.

More specifically, in step (b), the battery stack 5 may be charged at the initial charging voltage while being constrained to a constant pressure in the stacking direction of the layers constituting the unit batteries 1-4.

Here, constant pressure restraint can be achieved by the action of a constant pressure restraint mechanism including a constant pressure presser 10, a restraint plate 11, and restraint jigs 12 and 13. FIG. In this case, the constant pressure restraint mechanism can constrain the battery stack 5 at a constant pressure via a restraint plate 23 provided in the constant dimension restraint mechanism.

The constant-pressure presser may have any configuration that can keep the pressure applied to the battery stack substantially constant even if the layers constituting the unit battery expand. For example, the constant pressure presser may consist of a spring and/or piezo element, or it may be hydraulic (hydraulic) using a liquid. In either case, the battery stack may be constrained at a constant pressure while detecting pressure via, for example, an actuator and a controller, if necessary.

Also, the number of constant pressure pressers is not particularly limited, and can be set as appropriate in consideration of the balance between the size of the constant pressure pressers to be used and the size of the battery stack in the planar direction.

For example, in the constant pressure restraint mechanism shown in FIG. 1(a), nine constant pressure pressers 10 (shown in FIG. 1(a-1)) are used to Constant-pressure restraint can be uniformly applied to the battery stack 5 so that the surface pressure of a restraint plate 23 is not uneven.

Moreover, the spring constant of the constant pressure presser is not particularly limited, and can be appropriately set in consideration of the configuration and size of the battery stack. For example, it may be 0.5 N/mm or more, 1.0 N/mm or more, 1.5 N/mm or more, or 2.0 N/mm or more per 1 mm ² of the cross-sectional area in the plane direction of the battery stack, and It may be 5.0 N/mm or less, or 3.0 N/mm or less.

The pressure to be applied to the battery stack when constraining to a constant pressure is not particularly limited, and can be appropriately set in accordance with the configuration of the battery stack so as not to cause cracks or deformation due to expansion of the active material layer. can be done. For example, the pressure applied to the battery stack may be 2.0 MPa or more, 3.0 MPa or more, 4.0 MPa or more, 5.0 MPa or more, or 7.0 MPa or more, and 30.0 MPa or less and 20.0 MPa. Below, it may be 10.0 MPa or less, 8.0 MPa or less, or 6.0 MPa or less.

The constraining jig and constraining plate serve to fix the battery stack installed in the constant pressure constraining mechanism and the constant dimension constraining mechanism. That is, in the step (b), when the battery stack is charged at the initial charging voltage, even if the active material layers and the like constituting the unit cells of the battery stack expand, fixing the restraint jig will A constant pressure presser can provide a constant pressure restraint on the battery stack.

For example, in FIG. 1(a), when the battery stack 5 is charged at the initial charging voltage, even if the active material layers and the like constituting the unit batteries 1 to 4 of the battery stack 5 are expanded, the restraint treatment is performed. Fixings 12 and 13 and restraining plates 11 and 21 allow the constant pressure presser to restrain the battery stack at a constant pressure.

The battery stack can be activated by charging the battery stack with the initial charging voltage.

This initial charge voltage may be a voltage higher than the charge/discharge voltage controlled in the manufactured all-solid-state battery system. For example, when manufacturing an all-solid-state battery system in which the charging and discharging voltage is scheduled to be controlled within the range of 2.50 V or more and 4.40 V or less, the initial charging voltage is a value greater than 4.45 V and 5.00 V or less. can be selected.

Also, the initial charging up to a predetermined voltage may be performed by constant current charging. The charging rate in this case is not particularly limited, and may be about 0.1C to 10C, for example.

<Step (c)>
In the step (c), the battery stack is constrained to a fixed size in the stacking direction of the layers constituting the unit battery.

For example, after performing step (b) on the battery stack 5 shown in FIG. and step (c) can be performed.

Here, dimensional restraint can be achieved by dimensional restraint mechanisms including dimensional bars, restraining plates, and screws.

For example, the sizing bars 20 and 21 and the restraint plates 22 and 23 shown in FIG. can be dimensionally constrained.

Note that the sizing bar and the restraining plate may be fixed by means other than screws. For example, the sizing bar and the sizing plate may be fixed by welding or the like.

The battery stack constrained to a fixed size in step (c) may be assembled into a battery pack as an all-solid-state battery for use.

For example, when the constant-pressure/constant-dimension restraint mechanism of FIG. 1(a) is used, as shown in FIGS. , sizing bars 20 and 21, restraining plates 22 and 23, and screws 24-31 may be removed together from the constant pressure restraining mechanism and assembled into a battery pack as an all solid state battery.

<Other processes>
The method of the present disclosure may further comprise other steps between step (b) and step (c). For example, the method of the present disclosure includes (b-1) discharging the initially charged battery stack while constraining it to a constant pressure in the stacking direction of the layers constituting the unit battery, and (b-2) step ( After b-1), the battery stack may be charged normally while being constrained to a constant pressure in the stacking direction of the layers constituting the unit battery.

<Step (b-1)>
In step (b-1), the initially charged battery stack is discharged while being constrained to a constant pressure in the stacking direction of the layers constituting the unit battery.

The voltage for discharging is not particularly limited. For example, when manufacturing an all-solid-state battery system intended to be controlled within the range of 2.50V to 4.40V, the voltage may be discharged to 3.0V.

Also, discharge to a predetermined voltage may be performed by constant current discharge. The discharge rate in this case is not particularly limited, and may be about 0.1C to 10C, for example.

<Step (b-2)>
In step (b-2), after step (b-1), the battery stack is normally charged while being constrained to a constant pressure in the stacking direction of the layers constituting the unit battery.

The normal charging voltage is not particularly limited, and may be appropriately set according to the configuration of the battery stack. For example, charging may be performed to a voltage corresponding to 55% to 90% of the theoretical SOC (State Of Charge) of the battery stack.

Charging up to a predetermined voltage may be performed by constant current charging. The charging rate in this case is not particularly limited, and may be about 0.1C to 10C, for example.

Usually, it is preferable to hold the charged battery stack in a constant pressure restraint state for one hour to several hours before performing the subsequent step (c).

《All solid state battery》
The all-solid-state battery of the present disclosure manufactured by the method described above has one or more unit cells as a battery stack, and a sizing constraining mechanism.

Specific examples of constituent materials of each layer constituting the unit battery will be described below. In order to facilitate understanding of the present disclosure, a unit battery used for an all-solid-state lithium ion secondary battery will be described as an example, but the all-solid-state battery of the present disclosure is not limited to lithium ion secondary batteries, and can be widely used. Applicable.

(Positive electrode current collector layer)
The conductive material used for the positive electrode current collector layer is not particularly limited, and a material that can be used for all-solid-state batteries can be appropriately adopted. For example, the conductive material used for the positive electrode current collector layer may be SUS, aluminum, copper, nickel, iron, titanium, carbon, or the like, but is not limited to these.

The shape of the positive electrode current collector layer is not particularly limited, and examples thereof include a foil shape, a plate shape, and a mesh shape. Among these, the foil shape is preferred.

(Positive electrode active material layer)
The positive electrode active material layer contains at least a positive electrode active material, and preferably further contains a solid electrolyte, which will be described later. In addition, additives used in positive electrode active material layers of all-solid-state batteries, such as conductive aids and binders, can be included according to the intended use and purpose of use.

The material for the positive electrode active material is not particularly limited. For example, positive electrode active materials include lithium cobaltate ( _LiCoO2 ), lithium nickelate ( _LiNiO2 ), lithium manganate ( _LiMn2O4 ), LiCo1 _{/3Ni1 / 3Mn1 / 3O2} , and _Li1+x. A dissimilar element-substituted Li—Mn spinel or the like having a composition represented by Mn _2-xy M _y O ₄ (M is one or more metal elements selected from Al, Mg, Co, Fe, Ni, and Zn) may be, but are not limited to.

The conductive aid is not particularly limited. For example, the conductive aid may be a carbon material such as VGCF (Vapor Grown Carbon Fiber) and carbon nanofiber, a metal material, or the like, but is not limited thereto.

The binder is not particularly limited. For example, the binder may be, but is not limited to, materials such as polyvinylidene fluoride (PVdF), carboxymethylcellulose (CMC), butadiene rubber (BR) or styrene butadiene rubber (SBR), or combinations thereof.

(Solid electrolyte layer)
The solid electrolyte layer contains at least a solid electrolyte. The solid electrolyte is not particularly limited, and a material that can be used as a solid electrolyte for an all-solid battery can be used. For example, the solid electrolyte may be, but not limited to, a sulfide solid electrolyte, an oxide solid electrolyte, a polymer electrolyte, or the like.

Examples of sulfide solid electrolytes include, but are not limited to, sulfide-based amorphous solid electrolytes, sulfide-based crystalline solid electrolytes, and aldirodite-type solid electrolytes. Specific examples of sulfide solid electrolytes include Li ₂ S—P ₂ S ₅ systems (Li ₇ P ₃ S ₁₁ , Li ₃ PS ₄ , Li ₈ P ₂ S _9, etc.), Li ₂ S—SiS ₂ , LiI -Li ₂ S-SiS ₂ , LiI-Li ₂ SP ₂ S ₅ , LiI-LiBr-Li ₂ SP ₂ S ₅ , Li ₂ SP ₂ S ₅ -GeS ₂ (Li ₁₃ GeP ₃ S ₁₆ , Li ₁₀ GeP ₂ S ₁₂ , etc.), LiI—Li ₂ SP ₂ O ₅ , LiI—Li ₃ PO ₄ —P ₂ S ₅ , Li _7-x PS _6-x Cl _x , etc.; These include, but are not limited to:

_{Examples of oxide solid electrolytes include Li7La3Zr2O12 , Li7 - xLa3Zr1 -} xNbxO12 _{, Li7-3xLa3Zr2AlxO12} , _{Li3xLa2 / 3-x} TiO ₃ , Li _1+x Al _x Ti _2-x (PO ₄ ) ₃ , Li _1+x Al _x Ge _2-x (PO ₄ ) ₃ , Li ₃ PO ₄ , or Li _3+x PO _4-x N _x (LiPON ) and the like, but are not limited to these.

(polymer electrolyte)
Polymer electrolytes include, but are not limited to, polyethylene oxide (PEO), polypropylene oxide (PPO), copolymers thereof, and the like.

The solid electrolyte may be glass or crystallized glass (glass ceramic). Moreover, the solid electrolyte layer may contain a binder or the like as necessary, in addition to the solid electrolyte described above. Specific examples are the same as the "binder" listed in the above-mentioned "positive electrode active material layer", and the description thereof is omitted here.

(Negative electrode active material layer)
The negative electrode active material layer contains at least a negative electrode active material, and preferably further contains the solid electrolyte described above. In addition, additives used in the negative electrode active material layer of all-solid-state batteries, such as conductive aids and binders, can be included according to the intended use and purpose of use.

The material for the negative electrode active material is not particularly limited, and is preferably capable of intercalating and deintercalating metal ions such as lithium ions. For example, the negative electrode active material may be an alloy-based negative electrode active material, a carbon material, or the like, but is not limited to these.

The alloy-based negative electrode active material is not particularly limited, and examples thereof include a Si alloy-based negative electrode active material, a Sn alloy-based negative electrode active material, and the like. Si alloy-based negative electrode active materials include silicon, silicon oxides, silicon carbides, silicon nitrides, solid solutions thereof, and the like. In addition, the Si alloy-based negative electrode active material can contain elements other than silicon, such as Fe, Co, Sb, Bi, Pb, Ni, Cu, Zn, Ge, In, Sn, and Ti. Sn alloy-based negative electrode active materials include tin, tin oxides, tin nitrides, and solid solutions thereof. In addition, the Sn alloy-based negative electrode active material can contain elements other than tin, such as Fe, Co, Sb, Bi, Pb, Ni, Cu, Zn, Ge, In, Ti, and Si.

Among these, the Si alloy-based negative electrode active material is more preferable, but it is known that it tends to expand and contract with charging and discharging of the battery. From this point of view, the effects of the present disclosure can be expressed more remarkably when using a Si alloy-based negative electrode active material.

The carbon material is not particularly limited, and examples thereof include hard carbon, soft carbon, graphite, and the like.

As for the solid electrolyte, conductive aid, binder, and other additives used in the negative electrode active material layer, those described in the above items of "positive electrode active material layer" and "solid electrolyte layer" can be appropriately adopted. .

(Negative electrode current collector layer)
The conductive material used for the negative electrode current collector layer is not particularly limited, and a material that can be used for all-solid-state batteries can be appropriately employed. For example, the conductive material used for the negative electrode current collector layer may be SUS, aluminum, copper, nickel, iron, titanium, carbon, or the like, but is not limited to these.

The shape of the negative electrode current collector layer is not particularly limited, and examples thereof include a foil shape, a plate shape, and a mesh shape. Among these, the foil shape is preferred.

Hereinafter, the present disclosure will be described in detail in the form of examples. The following examples are in no way intended to limit the application of the present disclosure.

<<Example 1>>
A battery stack having unit batteries 1 to 4 was prepared.

This battery stack was set in a constant-pressure/constant-dimension restraint mechanism shown in FIG. 1(a). Then, the battery stack was charged at the initial charging voltage while being constrained to a constant pressure in the stacking direction of the layers constituting the unit battery.

More specifically, nine constant pressure pressers with a spring constant of 2 N/mm per 3 mm ² of cross-sectional area in the plane direction of the battery stack were used to apply a constant pressure of 5 MPa to the battery stack.

Initial charging was performed at 0.1 CA from voltage 0 to 4.55V. The pressure applied to the battery stack during charging at this initial charging voltage was constant at 5 MPa.

Next, when the voltage of the battery stack reached 4.55V, it was discharged to 3.0V at 0.1 CA.

After that, the battery was charged at a constant current of 0.3 CA up to a voltage of 3.8 V corresponding to SOC 60%, and held at 3.8 V for 1 hour.

Thereafter, in a state in which the constant pressure restraint mechanism is not functioning, the constraining plates and sizing bars at both ends of the battery stack are fixed with screws in the stacking direction of the layers constituting the unit battery, and the battery stack is assembled. , constrained to size.

Finally, the fixed-size constrained battery stack was removed from the constant-pressure constraining mechanism together with the constraining plate, the fixed-size bar, and the screws to produce the fixed-size constrained all-solid-state battery of Example 1.

<<Comparative example 1>>
After manufacturing the battery stack in Example 1 described above, the battery stack was constrained to a fixed size, and an all-solid-state battery of Comparative Example 1 was manufactured.

"evaluation"
<State of battery stack after initial charge>
For the battery stacks of Example 1 and Comparative Example 1, the end portions of each of the battery stacks before and after the initial charge were photographed with X-rays.

As a result, in the battery stack of Comparative Example 1, after the initial charge, the ends of the positive electrode active material layer, the negative electrode active material layer, and the solid electrolyte layer protruded compared to before the initial charge, and the portions that slid down. was there.

In contrast, the battery stack of Example 1 showed almost no change after the initial charge compared to before the initial charge. That is, in the battery stack of Example 1, deterioration of the battery due to initial charging was not observed.

<Battery performance>
The all-solid-state batteries of Example 1 and Comparative Example 1 were evaluated for impedance.

As a result, it was found that the impedance of the all-solid-state battery of Example 1 was smaller than that of the all-solid-state battery of Comparative Example 1. That is, the battery performance of the all-solid-state battery of Example 1 was better than the battery performance of the all-solid-state battery of Comparative Example 1.

1, 2, 3, 4 Unit battery 5 Battery laminate 1a Positive electrode current collector layer 1b Positive electrode active material layer 1c Solid electrolyte layer 1d Negative electrode active material layer 1e Negative electrode current collector layer 1f, 2f, 3f, 4f, 4g Current collector tab 10 constant pressure presser 11 restraint plate 12, 13 restraint jig 20, 21 sizing bar 22, 23 restraint plate 24, 25, 26, 27, 28, 29, 30, 31 screw

Claims (2)

A method for manufacturing an all-solid lithium ion secondary battery, comprising the following steps (a) and (b):
(a) Providing a battery laminate having at least one unit battery configured by laminating a positive electrode current collector layer, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector layer in this order. to do
(b) charging the battery stack at an initial charging voltage while constraining the battery stack to a constant pressure in the stacking direction of the layers constituting the unit battery ;
(c) constraining the battery stack to a constant size in the stacking direction of the layers constituting the unit battery, and the initial charging voltage being more than 4.45 V and not more than 5.00 V;
The constant pressure restraint is performed so as to prevent the restraint pressure applied to the battery stack from becoming excessively large due to the expansion and contraction of the battery stack during the initial charging,
The constant pressure restraint in the preceding step (b) and the constant dimension restraint in the preceding step (c) are performed by separate constant pressure restraint mechanisms and constant dimension restraint mechanisms, and
In the step (b), the battery stack is charged at the initial charging voltage while being constrained by the constant pressure restraint mechanism, and then in the step (c), the battery stack is removed from the constant pressure restraint mechanism. and constraining the constant dimension by the constant dimension restraint mechanism ,
Production method. 2. The method for manufacturing an all-solid lithium ion secondary battery according to claim 1 , wherein the constant pressure restraint is performed using a spring and/or a piezoelectric element and/or hydraulic pressure.

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