JP2016066469A - All-solid-state battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an all-solid-state battery capable of being safely deactivated while suppressing excessive voltage and a temperature rise in a simple structure, and further capable of being reused even after having been deactivated.SOLUTION: In an all-solid-state battery of the present invention, a positive electrode collector, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode collector are laminated. At a terminal 111 of the positive electrode collector and a terminal 112 of the negative electrode collector, a cross-linking body 120 cross-linking between the terminals of these collectors is arranged. The cross-linking body 120 is formed of a material having an electrical conductivity of 10(1/(Ω cm)) or less when the all-solid-state battery 100 is within an operational temperature range and an electrical conductivity of 10 (1/(Ω cm)) or more when the all-solid-state battery 100 is over an operational temperature range.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an all solid state battery. More specifically, the present invention relates to an all-solid-state battery that can be safely deactivated with a simple structure while suppressing excessive voltage and temperature rise, and can be reused even after deactivation. .

  In recent years, all-solid-state batteries in which the electrolytic solution is replaced with a solid electrolyte have attracted attention. Compared to a secondary battery using an electrolytic solution, an all-solid battery does not use an electrolytic solution, so that it does not cause decomposition of the electrolytic solution due to overcharge, and further has high cycle durability and energy density. Have.

  However, all the solid batteries have a problem that the internal temperature of the battery is short-circuited or rarely short-circuited due to an increase in battery temperature due to excessive charging or the like, an impact, or the like, and the temperature is further increased. Therefore, it has been desired to solve this problem.

  In the electrochemical device of Patent Document 1, the first and second dummy electrodes that are electrically connected to the positive electrode and the negative electrode, respectively, have opposing portions that face each other through the separator, and the opposing portions face each other. A resistance control layer is provided on the side, and when a short circuit occurs between the first and second dummy electrodes due to shrinkage or melting of the separator, the first dummy electrode, the resistance control layer, and the second dummy electrode are interposed. By making the positive electrode and the negative electrode conductive, an extremely gradual internal short circuit can be generated, and the safety of the electrochemical device in an abnormally high temperature atmosphere can be improved.

  In the battery of Patent Document 2, when the temperature inside the battery is excessively increased due to an abnormality such as overcharge or internal short circuit, the battery is in contact with the first electrical conductor in contact with the positive electrode connection member and the negative electrode connection member. It is said that the low melting point alloy layer disposed between the second electric conductor is melted, and the first electric conductor and the second electric conductor can be conducted to be short-circuited.

  In the lithium secondary battery of Patent Document 3, when the battery temperature exceeds 60 ° C., the shape memory alloy inside the battery is deformed by being heated, and the positive electrode and the negative electrode are conducted through the shape memory alloy, It is said to have a mechanism that can be short-circuited.

JP 2009-238493 A JP2013-98132A Japanese Patent No. 3468015

  In the electrochemical device of Patent Document 1, it is necessary to shrink or melt the separator in order to cause a gentle internal short circuit through the resistance control layer. Therefore, since the separator becomes unusable after the separator is contracted or melted and short-circuited, it is difficult to reuse the battery.

  Since the battery of Patent Document 2 causes an internal short circuit by melting the low melting point alloy layer, it is difficult to reuse the battery.

  The lithium secondary battery of Patent Document 3 includes a complicated short-circuit mechanism and causes a temperature increase due to a short circuit.

  Therefore, the present invention provides an all-solid-state battery that can be safely deactivated with a simple structure while suppressing excessive voltage and temperature rise, and can be reused even after deactivation. For the purpose.

  The present inventors have found that the above problem can be solved by providing a cross-linked body made of a material whose electrical conductivity increases when heated between the positive electrode and the negative electrode current collector. Completed. That is, the present invention is as follows.

<1> An all-solid battery in which a positive electrode current collector, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector are laminated,
Between the positive electrode current collector and the negative electrode current collector, a cross-linked body that cross-links between them is disposed,
The cross-linked body has an electric conductivity of 10 ⁻³ (1 / (Ω · cm)) or less when the all solid state battery is in an operating temperature range, and when the all solid state battery exceeds an operating temperature range. Formed of a material having an electrical conductivity of 10 (1 / (Ω · cm)) or more,
All solid battery.

  According to the present invention, there is provided an all-solid-state battery that can be safely deactivated with a simple structure, while suppressing excessive voltage and temperature rise, and can be reused even after deactivation. be able to.

FIG. 1 is a schematic front view of the first embodiment of the all solid state battery of the present invention. FIG. 2 is a schematic cross-sectional view of a second embodiment of the all solid state battery of the present invention. FIG. 3 is a schematic cross-sectional view of the third embodiment of the all solid state battery of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail. Note that the present invention is not limited to the following embodiments, and can be implemented with various modifications within the scope of the gist of the present invention. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may differ from the actual ratios.

  In the present invention, “the length of the cross-linked body” means the distance between the positive electrode current collector and the negative electrode current collector at the location where the cross-linked body is cross-linked, and “the cross-sectional area of the cross-linked body” Means the area of the cross-section of the cross-linked body when cut along a plane perpendicular to the length direction of the cross-linked body.

  In the all solid state battery of the present invention, a positive electrode current collector, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector are laminated. The all-solid battery may be entirely packaged in a film-like package or case. Such a film-like package or case may be formed of a polymer film, particularly a polymer film in which a metal foil such as aluminum is laminated.

<Crosslinked product>
Between the positive electrode and the negative electrode current collector, for example, between the positive electrode and the negative electrode current collector having a foil-shaped current collector main body and a terminal bonded to the end thereof, there is a bridge between them. A cross-linked body is arranged. The cross-linked body can be disposed at an arbitrary position where the cross-linked body is heated when the battery temperature rises. Therefore, the crosslinked body can be disposed between the positive electrode and the negative electrode current collector body or between the terminals of the positive electrode and the negative electrode current collector. When the cross-linked body is disposed between the positive electrode and the negative electrode current collector main body, it is possible to produce an all-solid battery more compactly than when the cross-linked body is disposed between the terminals of the positive electrode and the negative electrode current collector.

  Referring to FIG. 1, a first embodiment of the all solid state battery of the present invention is shown. The all-solid-state battery 100 of FIG. 1 has a positive electrode current collector terminal 111 and a negative electrode current collector terminal 112, and a cross-linked body 120 that is cross-linked to the terminals of the current collector.

  Referring to FIG. 2, a second embodiment of the all solid state battery of the present invention is shown. FIG. 2 is a schematic cross-sectional view of the all-solid battery 200 of the present invention. The all-solid battery 200 is a unit cell 210 in which a positive electrode active material layer 211, a solid electrolyte layer 212, and a negative electrode active material layer 213 are stacked in this order. And a single battery 220 in which these are stacked in the reverse order, a positive electrode current collector 231, a negative electrode current collector 232, and a cross-linked body 240.

  More specifically, in the all-solid-state battery 200, the positive electrode current collector 231, the single battery 210, the negative electrode current collector 232, the single battery 220, the positive electrode current collector 231, the single battery 210, and the negative electrode current collector 232 are the same. They are stacked in order. The current collector has a length slightly longer than the length of the unit cell in the plane direction of the stacked surface, so that one end of the current collector protrudes from the end of the unit cell. And the bridge | crosslinking body 240 is arrange | positioned between the parts which the electrical power collector protrudes.

  Referring to FIG. 3, a third embodiment of the all solid state battery of the present invention is shown. FIG. 3 is a schematic cross-sectional view of the all solid state battery 300 of the present invention. The all solid state battery 300 includes a unit cell 310 in which a positive electrode active material layer 311, a solid electrolyte layer 312 and a negative electrode active material layer 313 are stacked in this order. And a single battery 320 in which these are stacked in the reverse order, a positive electrode current collector 331, a negative electrode current collector 332, and a cross-linked body 340.

  More specifically, in the all-solid-state battery 300, the positive electrode current collector 331, the single battery 310, the negative electrode current collector 332, the single battery 320, the positive electrode current collector 331, the single battery 310, and the negative electrode current collector 332 are the same. They are stacked in order. This all-solid-state battery 300 is the same as the all-solid-state battery 200 of FIG. 2 except that the cross-linked body 340 is arranged not at the end of the battery but at the center.

The crosslinked body has an electric conductivity of 10 ⁻³ (1 / (Ω · cm)) or less when the all solid state battery is in the operating temperature range, and 10 (1 / (Ω · cm)) or more.

  Therefore, when the all solid state battery is in the operating temperature range, the crosslinked body functions as an insulator and does not hinder the flow of current due to conduction with the outside of the all solid state battery, and the all solid state battery exceeds the operating temperature range. Then, the crosslinked body functions as a conductor and can self-discharge the all solid state battery.

  The electrical conductivity of the crosslinked body when the all-solid battery exceeds the operating temperature range is adjusted in consideration of the discharge capacity, potential, operating temperature, etc. of the all-solid battery.

  Specifically, for example, by setting the electrical conductivity of the crosslinked body when the all solid state battery exceeds the operating temperature range to a predetermined range, the heat generation upper limit temperature of the crosslinked body is set higher than the heat generation upper limit temperature of the all solid state battery. By keeping it low, it is possible to self-discharge the battery while suppressing the heated cross-linked body from heating the all-solid battery, and the all-solid battery can be safely deactivated by the self-discharge. Therefore, according to the present invention, the all-solid-state battery can be reused while preventing or minimizing the damage.

  On the other hand, when the electrical conductivity of the crosslinked body is lower than the predetermined range when the all-solid battery is over the operating temperature range, it takes time to reach the discharge end voltage. There is a risk that the temperature will continue to rise and further shorts or rare shorts may occur.

  In addition, when the electrical conductivity of the crosslinked body when the all-solid battery exceeds the operating temperature range is higher than a predetermined range, the crosslinked body generates a large current and generates heat at a high temperature. There is a risk of heating the solid state battery.

For example, the conditions for keeping the heat generation upper limit temperature of the crosslinked body lower than the heat generation upper limit temperature of the all-solid battery can be expressed by the following formula (I):
ρL / A <V ² t / Q (I)
[Where:
ρ (Ω · cm): Resistivity of crosslinked body L (cm): Length of crosslinked body A (cm ² ): Cross-sectional area of crosslinked body V (J / c): Voltage of all solid state battery t (s): Time Q (J): Calorific value of all solid state battery]

  Hereinafter, the process of deriving the above formula (I) will be specifically described.

In order to keep the heat generation upper limit temperature of the crosslinked body lower than the heat generation upper limit temperature of the all-solid battery, the heat generation amount per unit time of the crosslinked body and the all-solid battery needs to satisfy the following formula (II). :
I ₁ ² R ₁ <I ₂ ² R ₂ (II)
[Where:
I ₁ (A): current flowing through the crosslinked body I ₂ (A): current flowing through the all-solid battery R ₁ (Ω · cm): resistance value of the crosslinked body R ₂ (Ω · cm): resistance value of the all-solid battery ]

When the all-solid-state battery exceeds the operating temperature range, the resistance value of the crosslinked body is sufficiently small, and the current flowing through the crosslinked body and the all-solid battery can be approximated to the same value. Therefore, I ₁ ≈I ₂ holds, and the following formula (III) is derived from the above formula (II):
R ₁ <R ₂ (III)

Furthermore, the resistance value R ₁ of the crosslinked product can be represented by the following formula (IV):
R ₁ = ρL / A (IV)

Further, from Ohm's law and Joule's law, the resistance value R ₂ of the all-solid-state battery can be expressed by the following equations (V) and (VI):
R ₂ = V / I ₂ (V)
Q = R ₂ I ₂ ² t = V ² t / R ₂ (VI)

From the above formulas (V) and (VI), the following formula (VII) is derived:
R ₂ = V ² t / Q (VII)

  The above formula (I) is derived from these formulas (III), (IV), and (VII).

  Since the electrical conductivity of the crosslinked body changes reversibly with respect to temperature change, the all-solid battery can be reused even after the all-solid battery is deactivated due to temperature rise.

  The heat generation upper limit temperature during conduction of the crosslinked body may be 200 ° C. or less, preferably 170 ° C. or less, and more preferably 150 ° C. or less.

The electrical conductivity of the cross-linked body is 10 ⁻³ (1 / (Ω · cm)) or less in the operating temperature range of the all-solid battery, preferably from the viewpoint of expressing insulation in the operating temperature range of the all-solid battery, preferably 10 ⁻⁴ (1 / (Ω · cm)) or less, more preferably 10 ⁻⁵ (1 / (Ω · cm)) or less.

The electrical conductivity of the cross-linked body is 10 when the operating temperature range of the all solid state battery is exceeded, from the viewpoint of expressing the electrical conductivity above the operating temperature range of the all solid state battery and adjusting the self-discharge of the all solid state battery. (1 / (Ω · cm)) or more, preferably 5 × 10 (1 / (Ω · cm)) or more, more preferably 10 ² (1 / (Ω · cm)) or more.

  The operating temperature range of the all solid state battery may be 200 ° C. or less, preferably 150 ° C. or less, more preferably 100 ° C. or less, particularly preferably 80 ° C. or less, from the viewpoint of safely operating the all solid state battery.

  The operating temperature range of the all solid state battery may be −200 ° C. or higher, preferably −150 ° C. or higher, more preferably −100 ° C. or higher, particularly preferably −30 ° C. or higher, from the viewpoint of operating the all solid state battery as a minimum. .

For example, when the temperature of the all-solid battery is in the range of −30 ° C. to 80 ° C., the crosslinked body can have an electric conductivity of 10 ⁻³ (1 / (Ω · cm)) or less, and the all-solid battery When the temperature is 80 ° C. or higher, the crosslinked body can have an electrical conductivity of 10 (1 / (Ω · cm)) or higher.

  The shape, length, and cross-sectional area of the crosslinked body may be any shape, length, and cross-sectional area as long as the electrical conductivity of the crosslinked body can be set as described above. For example, the electrical conductivity of the crosslinked body is generally proportional to the size of the cross-sectional area of the crosslinked body and inversely proportional to the length of the crosslinked body. The cross-linked body may have a shape with good heat dissipation efficiency, for example, a plate shape.

As a constituent material of the crosslinked body, any material may be used as long as the electrical conductivity can be adjusted as described above. For example, examples of the constituent material of the crosslinked body include, but are not limited to, semiconductor materials such as NTC thermistor and vanadium dioxide (VO ₂ ).

<Positive electrode and negative electrode current collector>
As the positive electrode or the negative electrode current collector, any current collector can be used. For example, various metal current collectors such as aluminum, nickel, iron, stainless steel, titanium, or copper can be used.

  The current collector can optionally have a foil-like current collector body and a terminal bonded to the end thereof.

  As a constituent material of the current collector main body and the current collector terminal, any constituent material may be used as long as it can be electrically connected to the outside.For example, the current collector main body and the current collector terminal may be the same constituent material. Different constituent materials may be used.

  The shape of the terminal of the current collector may be any shape as long as it can be electrically connected to the outside, and preferably a shape capable of forming a crosslinked body between the terminals of the positive electrode and the negative electrode current collector. Examples of the shape of the terminals of the current collector include, but are not limited to, a polygon such as a triangle and a quadrangle, a giboshi shape, an L shape, and a taper shape.

  The terminals of the current collector may be arranged arbitrarily as long as they can be electrically connected to the outside.For example, the terminals of the positive electrode and the negative electrode current collector are arranged at positions close to each other, and a cross-linked body is interposed between these terminals. You may make it easy to form.

<Positive electrode active material layer>
The positive electrode active material layer contains a positive electrode active material, and optionally a conductive additive and a solid electrolyte material.

As the positive electrode active material, at least one transition metal selected from manganese, cobalt, nickel and titanium and a metal oxide containing lithium, such as lithium cobaltate (Li _x CoO ₂ ), lithium nickelate (Li _x NiO ₂ ) And nickel cobalt lithium manganate (Li _{1 + x} Ni _3/5 Co _1/5 Mn _1/5 O ₂ ).

  Examples of the conductive aid include VGCF (vapor grown carbon fiber), carbon materials such as carbon black, ketjen black, carbon nanotubes, and carbon nanofibers, and metal materials.

As the solid electrolyte material, a material that can be used as a solid electrolyte of an all-solid battery can be used. For example, Li ₂ S, P ₂ S ₅ , Li ₂ S—SiS ₂ , LiI—Li ₂ S—SiS ₂ , LiI—Li ₂ S—P ₂ S _5, or LiI—Li ₂ S—B ₂ S _3, etc. Sulfide-based amorphous solid electrolyte, oxide-based amorphous solid electrolyte such as Li ₂ O—B ₂ O ₃ —P ₂ O ₅ or Li ₂ O—SiO ₂ , or Li _1.3 A _10.3 Ti _0.7 (PO ₄ ) ₃ or Li _{1 + x + y} A _x Ti _{2 -x} Si _y P _{3 -yO 12} (A is Al or Ga, 0 ≦ x ≦ 0.4, 0 <y ≦ 0.6), etc. A crystalline oxide or the like can be used. A sulfide-based amorphous solid electrolyte is preferably used in that it has excellent lithium ion conductivity. Further, as the solid electrolyte material, a semi-solid polymer electrolyte such as polyethylene oxide, polypropylene oxide, polyvinylidene fluoride, or polyacrylonitrile containing a lithium salt can also be used.

<Solid electrolyte layer>
The solid electrolyte layer contains a solid electrolyte material. As the solid electrolyte material, the materials mentioned for the positive electrode active material layer can be used.

<Negative electrode active material layer>
The negative electrode active material layer contains a negative electrode active material, and optionally a conductive additive and a solid electrolyte material.

  The negative electrode active material is not particularly limited as long as it can occlude / release metal ions such as lithium ions. For example, a metal such as Li, Sn, Si or In, an alloy of lithium and titanium, magnesium or aluminum, or Examples thereof include carbon materials such as hard carbon, soft carbon, and graphite.

  As the conductive auxiliary agent and the solid electrolyte material, the materials mentioned for the positive electrode active material layer can be used.

  Although preferred embodiments of the present invention have been described in detail, the arrangement and type of all-solid-state batteries, positive and negative electrode current collectors, and cross-linked bodies used in the present invention without departing from the scope of the claims. Those skilled in the art will appreciate that modifications are possible.

100, 200, 300 All-solid-state battery 111 Terminal of positive electrode current collector 112 Terminal of negative electrode current collector 120 Cross-linked body 210, 220, 310, 320 Single cell 211, 311 Positive electrode active material layer 212, 312 Solid electrolyte layer 213, 313 Negative electrode active material layer 231, 331 Positive electrode current collector 232, 332 Negative electrode current collector 240, 340 Crosslinked body

Claims (1)

An all-solid battery in which a positive electrode current collector, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector are laminated,
Between the positive electrode current collector and the negative electrode current collector, a cross-linked body that cross-links between them is disposed,
The cross-linked body has an electric conductivity of 10 ⁻³ (1 / (Ω · cm)) or less when the all solid state battery is in an operating temperature range, and when the all solid state battery exceeds an operating temperature range. Formed of a material having an electrical conductivity of 10 (1 / (Ω · cm)) or more,
All solid battery.

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