JP2015076158A - All-solid secondary battery, manufacturing method of the same, and sensor system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit deterioration caused by repetitive charging/discharging in an all-solid secondary battery, a manufacturing method of the all-solid secondary battery, and a sensor system.SOLUTION: An all-solid secondary battery includes: a substrate 2; a battery part 6 formed by laminating a first electrode 3, a solid electrolyte 4, and a second electrode 5 on the substrate 2 in sequence; a frame 11 provided around the battery part 6; and a sealing film 7 covering the battery part 6 and the frame 11.

Description

  The present invention relates to an all-solid secondary battery, a method for producing an all-solid secondary battery, and a sensor system.

  Secondary batteries such as lithium ion secondary batteries that can repeatedly supply electric energy by charging and discharging are being applied to various devices.

  The electrolyte included in the secondary battery is liquid or solid, and the secondary battery having a solid electrolyte is called an all-solid secondary battery. The all-solid-state secondary battery is safe because it does not leak because the electrolyte is solid. Furthermore, since the all-solid-state secondary battery can be formed by a semiconductor process, there is an advantage that it is easy to manufacture.

JP 2010-73687 A

  It is an object of the present invention to improve reliability in an all-solid secondary battery, an all-solid secondary battery manufacturing method, and a sensor system.

  According to one aspect of the disclosure below, a substrate, a battery unit in which a first electrode, a solid electrolyte, and a second electrode are sequentially stacked on the substrate, and the periphery of the battery unit are provided. An all solid state secondary battery having a frame and a sealing film covering the battery part and the frame is provided.

  Further, according to another aspect of the disclosure, a battery unit is formed by sequentially stacking a first electrode, a solid electrolyte, and a second electrode inside the frame, the step of forming a frame on the substrate. There is provided a method for producing an all-solid-state secondary battery including a forming step and a step of forming a sealing film that covers the battery part and the frame.

  According to another aspect of the disclosure, the all-solid-state secondary battery, a sensor that is driven by the power stored in the all-solid-state secondary battery, and the power that is stored in the all-solid-state secondary battery are driven, A transmission unit that wirelessly transmits information from the sensor, and the all-solid-state secondary battery includes: a battery unit in which a first electrode, a solid electrolyte, and a second electrode are sequentially stacked; and There is provided a sensor system having a frame provided around, and a sealing film covering the battery part and the frame.

  According to the following disclosure, even when the height of the battery part is changed due to charging / discharging, it is possible to suppress the sealing film from being stretched and contracted by the battery part with a frame. Thereby, the stress applied repeatedly to the sealing film can be suppressed, and a highly reliable all-solid secondary battery that is difficult to crack the sealing film can be provided.

FIG. 1 is a cross-sectional view of an all solid state secondary battery investigated by the present inventors. FIG. 2 is a charge / discharge curve of the all-solid-state secondary battery. FIG. 3A is a cross-sectional view of an all-solid-state secondary battery having a first charge amount examined by the inventor of the present application, and FIG. 3B is an entire view of the second charge amount examined by the present inventor. It is sectional drawing of a solid secondary battery. FIG. 4 is a cross-sectional view of the all solid state secondary battery according to the first embodiment. FIG. 5A is a cross-sectional view of the all-solid-state secondary battery according to the first embodiment at the first charge amount, and FIG. 3B is the first embodiment at the second charge amount. It is sectional drawing of the all-solid-state secondary battery which concerns on a form. FIG. 6 is a diagram obtained by calculating how the stress applied to the sealing film varies depending on the height of the protective frame in the all-solid-state secondary battery according to the first embodiment. FIG. 7 is a cross-sectional view (part 1) in the middle of manufacturing the all-solid-state secondary battery according to the first embodiment. FIG. 8 is a cross-sectional view (No. 2) in the middle of manufacturing the all solid state secondary battery according to the first embodiment. FIG. 9 is a cross-sectional view (No. 3) in the middle of manufacturing the all solid state secondary battery according to the first embodiment. FIG. 10 is a cross-sectional view (part 4) in the middle of manufacturing the all-solid-state secondary battery according to the first embodiment. FIG. 11 is a cross-sectional view (part 5) of the all-solid-state secondary battery according to the first embodiment in the middle of manufacture. FIG. 12 is a cross-sectional view (No. 6) of the all solid state secondary battery according to the first embodiment in the middle of manufacture. FIG. 13 is a sectional view (No. 7) in the middle of manufacturing the all solid state secondary battery according to the first embodiment. FIG. 14 is a plan view (part 1) in the middle of manufacturing the all-solid-state secondary battery according to the first embodiment. FIG. 15 is a plan view (part 2) of the all-solid-state secondary battery according to the first embodiment during manufacture. FIG. 16 is a cross-sectional view illustrating another example of the all solid state secondary battery according to the first embodiment. FIG. 17 is a functional block diagram of a sensor system according to the second embodiment.

  Prior to the description of the present embodiment, items studied by the inventor will be described.

  FIG. 1 is a cross-sectional view of an all-solid secondary battery 1 examined by the present inventors.

  As shown in FIG. 1, the all-solid-state secondary battery 1 has a battery unit 6 formed by sequentially laminating a first electrode 3, an electrolyte 4, and a second electrode 5 on a substrate 2. The height of the battery unit 6 measured from the surface of the substrate 2 is T, and the battery unit 6 is covered with a sealing film 7.

The substrate 2 is a silicon substrate, for example. The first electrode 3 is a positive electrode of the battery unit 6 and is made of a material such as lithium cobalt oxide (LiCoO ₂ ). And the 2nd electrode 5 is a negative electrode of the battery part 6, and is formed from materials, such as lithium (Li).

  The electrolyte 4 is a solid, and a material thereof is a lithium salt such as lithium phosphate (LiPON). The material of the sealing film 7 includes a resin such as acrylic.

  Further, a first current collector 8 is provided between the first electrode 3 and the substrate 2, and a second current collector 9 is provided on the second electrode 5. The material of each current collector 8, 9 is, for example, platinum (Pt), and charging / discharging of the battery unit 6 is performed via these current collectors 8, 9.

  FIG. 2 is a charge / discharge curve of the all solid state secondary battery 1.

As shown in the discharge curve of FIG. 2, the voltage value of the all-solid-state secondary battery 1 rapidly decreases when the voltage value thereof drops below about 3.0 V due to discharge. Therefore, the point where the voltage value is 3.0 V is a reference voltage value at which the all-solid-state secondary battery 1 is completely discharged. Hereinafter, the capacity of the all-solid-state secondary battery 1 corresponding to the voltage value is the first value. Called the charge amount C ₁ .

Further, as shown in the charging curve of FIG. 2, when the voltage value of the all-solid-state secondary battery 1 becomes higher than about 4.1 V by charging, the voltage value rises gradually. Therefore, the point where the voltage value is 4.1 V is a standard voltage value at which the charging of the all-solid-state secondary battery 1 is completed. Hereinafter, the capacity of the all-solid-state secondary battery 1 corresponding to the voltage value is set to the second value. referred to as the amount of charge C _2.

3A is a cross-sectional view of the all-solid-state secondary battery 1 having the first charge amount C ₁ , and FIG. 3B is a cross-section of the all-solid-state secondary battery 1 having the second charge amount C _2. FIG.

As shown in FIG. 3A, the height T of the battery unit 6 has a first height T ₁ when the charge amount is C ₁ .

When the battery unit 6 is charged in this state, lithium ions (Li ⁺ ) are released from the lithium cobalt oxide crystal of the first electrode 3.

Then, as shown in FIG. 3 (b), the lithium ions (Li ⁺ ) reach the lower surface of the second electrode 5 through the electrolyte 4, where they are combined with electrons, whereby the lithium metal layer 10 is formed. It is formed.

As a result, the height T of the battery unit 6 is increased by the thickness T _Li of the metal layer 10, and the second height T ₂ = T ₁ + T _Li is obtained.

On the contrary, during discharge, lithium in the metal layer 10 emits electrons to become lithium ions (Li ⁺ ), and the lithium ions move to the first electrode 3. As a result, lithium ions are occluded in the first electrode 3, and the metal layer 10 is thinned to reduce the height T ₂ of the battery unit 6.

  Thus, the height T of the all-solid-state secondary battery 1 changes with charge / discharge. As a result, stress repeatedly acts on the sealing film 7, and a crack 7 a may enter the sealing film 7.

  The sealing film 7 plays a role of protecting the battery unit 6 containing lithium from moisture in the atmosphere. When the crack 7a is generated in this way, external moisture enters the battery unit 6 from the crack 7a. However, moisture and lithium may react to generate heat or ignite.

  In particular, in the lower portion D of the sealing film 7, the portion of the sealing film 7 fixed to the substrate 2 cannot move up and down, so that stress acts strongly, and the crack 7a as described above is likely to occur.

  As described above, the all-solid-state secondary battery 1 has room for improvement in terms of reducing the stress acting on the sealing film and improving its reliability.

(First embodiment)
FIG. 4 is a cross-sectional view of the all-solid-state secondary battery 21 according to this embodiment. In FIG. 4, the same elements as those described in FIG. 1 are denoted by the same reference numerals as those in FIG. 1, and the description thereof is omitted below.

  As shown in FIG. 4, the all-solid-state secondary battery 21 has a battery unit 6 formed by sequentially laminating a first electrode 3, an electrolyte 4, and a second electrode 5 on a substrate 2.

The substrate 2 is, for example, a silicon substrate, and an insulating film (not shown) such as a silicon oxide (SiO ₂ ) film is formed thereon.

  The 1st electrode 3 functions as a positive electrode of the battery part 6, is formed from materials, such as lithium cobaltate, The film thickness is 6 micrometers, for example.

  And the electrolyte 4 is formed from the material containing lithium salts, such as lithium phosphate, The film thickness is 2 micrometers, for example.

  The second electrode 5 functions as a negative electrode of the battery unit 6 and is formed with a thickness of, for example, 2 μm from a material such as metallic lithium.

  Further, a first current collector 8 is provided between the first electrode 3 and the substrate 2, and a second current collector 9 is provided on the second electrode 5. The current collectors 8 and 9 are, for example, platinum films, and the battery unit 6 is charged / discharged through the current collectors 8 and 9.

Then, around the battery unit 6, an insulating protective frame 11 is provided having a height T _h. The material of the protective frame 11 is not particularly limited, but in this example, the protective film 11 is formed of alumina.

  Further, the protective frame 11 and the battery unit 6 are covered with a sealing film 7 made of a resin such as acrylic.

  Next, the operation of the all solid state secondary battery 21 according to this embodiment will be described with reference to FIGS. 5 (a) and 5 (b).

5A is a cross-sectional view of the all-solid-state secondary battery 21 having the first charge amount C ₁ , and FIG. 5B is a cross-section of the all-solid-state secondary battery 21 having the second charge amount C _2. FIG.

As described above, the first charge amount C ₁ is the capacity of the all-solid-state secondary battery 21 when the discharge is completed, and the second charge amount C ₂ is the capacity of the all-solid-state secondary battery 21 when the charge is completed. .

As shown in FIG. 5A, when the discharge is completed, the height of the battery unit 6 decreases to the _first height T ₁ as described above.

On the other hand, when the charging is completed, as shown in FIG. 5B, the height of the battery portion 6 is reduced to the second height T ₂ by the metal layer 10 formed by depositing metallic lithium. To increase.

  Here, in this embodiment, since the periphery of the battery unit 6 is surrounded by the protective frame 11, the battery unit 6 and the sealing film 7 are isolated on the side surface of the battery unit 6.

  Therefore, even if the height of the battery part 6 changes as described above, stress does not directly act on the sealing film 7 on the side surface of the protective frame 11 from the battery part 6, and the sealing film is caused by the stress. 7 can be prevented from cracking.

  Thereby, it is possible to prevent moisture in the atmosphere from entering the battery unit 6 from the crack of the sealing film 7, and the possibility that the battery unit 6 generates heat due to contact with moisture is reduced. Can improve the reliability.

Although the height T _h of the protective frame 11 is not particularly limited, the first higher than the height T _1, and to set the second lower than the height T ₂ as the height T _h Is preferred. Thereby, as shown in FIG. 5B, the difference Δ between the heights of the protective frame 11 and the second electrode 5 at the completion of charging becomes smaller than the thickness T _Li of the metal layer 10, and the battery unit It becomes easy to reduce the stress which the sealing film 7 receives above 6.

  The inventor of the present application calculated how the stress applied to the sealing film 7 changes depending on the height of the protective frame 11.

  The calculation result is shown in FIG.

The horizontal axis in FIG. 6 represents the difference (T _h −T ₁ ) between the heights _Th and T ₁ in FIG. 5A, and the vertical axis represents the stress that the sealing film 7 receives. The difference (T _h −T ₁ ) corresponds to the difference in height between the battery unit 6 and the protective frame 11 in the state when the discharge is completed.

The model of the battery unit 6 used for this calculation was a square with a side length of 5 mm in plan view. The model of the protective frame 11 was a square having a side length of 5.2 mm in plan view. Further, the thickness T _Li of the metal layer 10 (see FIG. 5B) upon completion of charging was set to 1 μm. Since the thickness T _Li of the metal layer 10 is equal to the difference (T ₂ −T ₁ ) between the aforementioned heights T ₁ and T ₂ , T ₂ −T ₁ = 1 μm.

As shown in FIG. 6, as the difference (T _h −T ₁ ) increases, the stress applied to the sealing film 7 decreases.

In particular, when the difference (T _h −T ₁ ) is in the range of 0 μm to 0.5 μm, the stress is drastically reduced. When the difference (T _h −T ₁ ) is larger than 0.5 μm, the stress is gently reduced. Since T ₂ −T ₁ = 1 μm as described above, when T _h −T ₁ is equal to 0.5 μm, T _h = (T ₁ + T ₂ ) / 2. Therefore, the stress applied to the sealing film 7 is sufficiently reduced by making the height of the protective frame 11 higher than one half of the sum of the first height T ₁ and the second height T _2. can do.

  Next, a manufacturing method of the all solid state secondary battery according to the present embodiment will be described.

  7-13 is sectional drawing in the middle of manufacture of the all-solid-state secondary battery 21 which concerns on this embodiment. 14 and 15 are plan views of the all-solid-state secondary battery 21 according to this embodiment in the middle of manufacture.

  First, as shown in FIG. 7, a silicon substrate having an oxide film (not shown) such as a silicon oxide film formed on the surface is prepared as the substrate 2. Then, a metal mask (not shown) is disposed above the substrate 2, and a titanium film and a platinum film are formed in this order by sputtering on the portion of the substrate 2 that is not covered with the metal mask film. 1 current collector 8. The titanium film functions as an adhesion film that improves the adhesion between the platinum film and the substrate 2.

  The film thickness of the first current collector 8 is not particularly limited, but in this example, the film thickness is about 200 nm.

  Next, as shown in FIG. 8 and FIG. 14, alumina is deposited on the substrate 2 by a sputtering method, and is patterned by a lift-off method, so that the protective frame 11 is formed on the substrate 2 to about 10.7 μm. Form to thickness.

  The protective frame 11 can be formed by a printing method instead of the sputtering method. In that case, the alumina of the protective frame 11 is sintered by heat-treating the protective frame 11 at a substrate temperature of about 1500 ° C. to 1600 ° C.

  In addition, the heat treatment temperature may be lowered by adding silicon oxide to the protective frame 11.

  Further, a resin may be used as a material for the protective frame 11 instead of ceramic such as alumina.

  Subsequently, as shown in FIG. 9, a mask 12 having a window 12a is disposed above the substrate 2, and cobalt acid is sputtered onto the first current collector 8 in the protective frame 11 through the window 12a. By supplying lithium, the first electrode 3 is formed in the protective frame 11 to a thickness of about 6 μm.

  Note that the first electrode 3 may be formed by a printing method instead of the sputtering method.

  Thereafter, a heat treatment is performed on the first electrode 3 to set the substrate temperature to about 600 ° C. in the atmosphere, and the lithium cobalt oxide of the first electrode 3 is crystallized.

  Next, as shown in FIG. 10, a mask 13 having a window 13 a is disposed above the substrate 2. Then, lithium phosphate is supplied onto the first electrode 3 by the sputtering method through the window 13a, thereby forming the electrolyte 4 in the protective frame 11 to a thickness of about 2 μm.

  Subsequently, as shown in FIG. 11, a mask 14 different from the above is disposed above the substrate 2. Then, lithium is supplied onto the electrolyte 4 through the window 14 a provided in the mask 14 by sputtering, thereby forming the second electrode 5 having a thickness of about 2 μm in the protective frame 11.

  In addition, by forming the second electrode 5 after forming the first electrode 3 as in this example, the second electrode 5 is subjected to heat treatment for crystallizing lithium cobalt oxide of the first electrode 3. It is not exposed and the lithium of the second electrode 5 can be prevented from melting by the heat treatment.

  Through the steps so far, a battery unit 6 is obtained in which the first electrode 3, the electrolyte 4, and the second electrode 5 are laminated in this order.

  Next, steps required until a sectional structure shown in FIG.

  First, the mask 15 is disposed above the second electrode 5. Then, a platinum film having a thickness of about 200 μm is formed on each of the portions of the second electrode 5 and the substrate 2 that are not covered with the mask 15 by vapor deposition, and the platinum film is formed on the second current collector 9. And

  FIG. 15 is a plan view at the time when this process is completed.

  The battery unit 6 is, for example, a square having a side length of about 5 mm in plan view, and the protective frame 11 is provided around the battery unit 6. The planar size of the protective film 11 is not particularly limited, but in this example, the protective frame 11 is formed in a square having a side length of about 5.2 mm.

  After that, as shown in FIG. 13, a resin material such as acrylic is sprayed on the battery unit 6 and the protective frame 11 in a vacuum to form a sealing film 7 that covers the battery unit 6 and the protective frame 11. Thus, instead of a single acrylic layer, a film formed by laminating an acrylic layer and a metal layer in this order may be formed as the sealing film 7.

  As described above, the basic structure of the all-solid-state secondary battery 21 according to this embodiment is completed.

  Note that the present embodiment is not limited to the above.

  FIG. 16 is a cross-sectional view showing another example of the all solid state secondary battery according to the present embodiment.

  In this example, the protective frame 11 is formed of a metal such as copper or aluminum, and the insulating film 16 such as a silicon oxide film is formed on the surface of the protective frame 11. 11 is electrically insulated.

  Thus, if a metal is employ | adopted as a material of the protective frame 11, the protective frame 11 can be easily formed by plating etc. As a method for forming the insulating film 16, for example, there is a MOCVD (Metal Organic Chemical Deposition) method having excellent step coverage.

(Second Embodiment)
In the present embodiment, the all solid state secondary battery 21 described in the first embodiment is applied to a sensor system.

  FIG. 17 is a functional block diagram of the sensor system according to the present embodiment.

  As shown in FIG. 17, the sensor system 30 includes a power generation element 20 such as a thermoelectric conversion element, and an all-solid-state secondary battery 21 that stores electric power generated by the power generation element 20.

The all-solid-state secondary battery 21 supplies power to the sensor 22 and the transmission unit 23. The sensor 22 is a temperature sensor, a vibration sensor, or the like that is driven by the power of the all-solid-state secondary battery 21, and sends information S ₁ related to the environment such as temperature and vibration to the transmission unit 23.

The transmitter 23 is driven by the power of the all-solid-state secondary battery 21 and wirelessly transmits the information S ₁ via the first antenna 24 using an appropriate communication protocol. The wirelessly transmitted information S ₁ is received by the receiving device 26 owned by the user via the second antenna 25.

  The receiving device 26 is, for example, a personal computer, and information related to the environment such as the temperature described above is displayed on the screen.

  According to the present embodiment described above, since the highly reliable all-solid secondary battery 21 that does not easily crack in the protective film 7 (see FIG. 4) is used, information such as temperature related to the environment over a long period of time. It is possible to acquire and stably provide the information to the user.

DESCRIPTION OF SYMBOLS 1, 21 ... All-solid-state secondary battery, 2 ... Board | substrate, 3 ... 1st electrode, 4 ... Electrolyte, 5 ... 2nd electrode, 6 ... Battery part, 7 ... Sealing film, 8, 9 ... Current collector DESCRIPTION OF SYMBOLS 10 ... Metal layer, 11 ... Protective frame, 12-15 ... Mask, 12a-14a ... Opening, 16 ... Insulating film, 20 ... Power generation element, 22 ... Sensor, 23 ... Transmitter, 24, 25 ... Antenna, 26 ... Receiver equipment.

Claims (6)

A substrate,
A battery part in which a first electrode, a solid electrolyte, and a second electrode are sequentially laminated on the substrate;
A frame provided around the battery unit;
A sealing film covering the battery part and the frame;
An all solid state secondary battery.   2. The all solid body according to claim 1, wherein the frame is higher than a first height of the battery part having a first charge amount and lower than a second height of the battery part having a second charge amount. Secondary battery.   The said 1st charge amount is the charge amount at the time of completion of discharge of the said battery part, The said 2nd charge amount is the charge amount at the time of completion of charge of the said battery part, The Claim 2 characterized by the above-mentioned. All-solid secondary battery.   4. The all-solid-state secondary battery according to claim 3, wherein the frame is higher than a height that is a half of a sum of the first height and the second height. 5. Forming a frame on the substrate;
Forming a battery part by sequentially laminating a first electrode, a solid electrolyte, and a second electrode inside the frame;
Forming a sealing film covering the battery part and the frame;
The manufacturing method of the all-solid-state secondary battery which has this. An all-solid-state secondary battery;
A sensor that is driven by the electric power stored in the all-solid-state secondary battery;
Driven by the power stored in the all-solid-state secondary battery, and having a transmitter that wirelessly transmits information from the sensor,
The all-solid-state secondary battery includes a battery part in which a first electrode, a solid electrolyte, and a second electrode are sequentially laminated, a frame provided around the battery part, the battery part, and the frame. And a sealing film covering the sensor.

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