JP6862689B2 - Monitoring method for all-solid-state secondary battery, power supply and all-solid-state secondary battery - Google Patents

Description

The present invention relates to an all-solid-state secondary battery, a power supply device having an all-solid-state secondary battery, and a method for monitoring the all-solid-state secondary battery.

Lithium-ion secondary batteries used as power sources for portable devices such as laptop computers, mobile phones, and smartphones are known. In a lithium ion secondary battery, an organic solution-based electrolyte is used as the electrolyte. Further, in order to further improve the safety of the lithium ion secondary battery, an all-solid-state secondary battery using an inorganic solid electrolyte instead of the organic solution-based electrolyte is known.

For example, a lithium ion secondary battery is known in which a solid electrolyte interposed between a negative electrode and a positive electrode is formed into two layers, and a buffer layer which is a solid electrolyte having enhanced reduction resistance of the solid electrolyte is inserted between them (for example,). See Patent Document 1). Further, a lithium ion secondary battery having a structure in which a single negative electrode is sandwiched between the first and second electrolytes and the sandwiched object is further sandwiched between the first and second positive electrodes is known (for example,). See Patent Document 2). Further, a second solid layer is formed by a vapor phase method on the first solid layer formed by pressure molding the powder and heat treatment, and two solid layers are laminated to form an all-solid secondary. It is known to prevent the occurrence of defects in the solid layer of a battery (see, for example, Patent Document 3).

Japanese Unexamined Patent Publication No. 2004-213938 Japanese Unexamined Patent Publication No. 2012-138290 Japanese Unexamined Patent Publication No. 2013-89470

"Battery checker" BCW "" NTT Data Advanced Technology Co., Ltd., [online], [Searched on May 26, 2016], <URL: http://www.intellilink.co.jp/solutions/green/produces/ battery>

However, with a conventional all-solid-state secondary battery, it is not easy to detect a sign that a short circuit occurs between the negative electrode and the positive electrode.

An object of the present invention is to provide an all-solid-state secondary battery capable of detecting a sign that a short circuit occurs between a negative electrode and a positive electrode.

In one embodiment, the monitoring method for the all-solid secondary battery is a method of monitoring the positive electrode layer, the negative electrode layer, the solid electrolyte disposed between the negative electrode and the positive electrode, and the negative electrode and the positive electrode arranged between the solid electrolytes. The solid electrolyte has a negative electrode and an intermediate layer, which can provide an alkali metal ion which is an ion species exchanged between the two, and has an intermediate layer having biconductivity capable of conducting both the alkali metal ion and an electron. A first solid electrolyte arranged between the electrodes and containing an alkali metal ion, and a second solid electrolyte arranged between the positive electrode and the intermediate layer and containing an alkali metal ion. When the output is measured, the presence or absence of a short circuit between the negative electrode and the intermediate layer is determined based on the measured output, and it is determined that a short circuit has occurred between the negative electrode and the intermediate layer, the all-solid secondary battery Outputs a short-circuit sign signal indicating that there is a short-circuit sign in.

As one aspect, in an all-solid-state secondary battery, it becomes possible to detect a sign that a short circuit occurs between the negative electrode and the positive electrode.

(A) is a diagram showing the structure of the all-solid-state secondary battery related to the all-solid-state secondary battery according to the embodiment, and (b) is based on the negative electrode in the normal state of the all-solid-state secondary battery shown in (a). It is a figure which shows the change of the potential as a potential, (c) is the figure which shows the change of the potential with the negative electrode as a reference potential when the negative electrode and the positive electrode of the all-solid-state secondary battery shown in (a) are short-circuited. Is. (A) is a diagram showing the structure of the all-solid-state secondary battery according to the embodiment, and (b) shows the change in the potential of the all-solid-state secondary battery shown in (a) with the negative electrode in the normal state as a reference potential. It is a figure (c) is a figure which shows the change of the potential with the negative electrode as a reference potential at the time of short-circuiting between the negative electrode and the intermediate layer of the all-solid-state secondary battery shown in (a). (A) is a diagram showing a change in the potential difference between the negative electrode and the positive electrode when the negative electrode and the intermediate layer are short-circuited during charging in the all-solid-state secondary battery according to the embodiment, and FIG. It is a figure which shows the change of the potential difference between a negative electrode and a positive electrode when the negative electrode and the positive electrode are short-circuited during charging in a conventional all-solid-state secondary battery. It is a circuit block diagram of the power supply unit including the all-solid-state secondary battery which concerns on embodiment. (A) is a diagram showing the switching state of the first switch and the second switch when charging the all-solid-state secondary battery, and (b) is the first switch and the second switch when discharging the all-solid-state secondary battery. It is a figure which shows the switching state of a switch. It is a flowchart of the battery monitoring process by a power supply unit. (A) is a diagram showing the structure of the all-solid-state secondary battery according to the embodiment, and (b) is a perspective view of the all-solid-state secondary battery shown in (a). (A) is a diagram showing the structure of the all-solid-state secondary battery according to the comparative example, and (b) is a side view of the all-solid-state secondary battery shown in (a). (A) is a diagram showing the relationship between capacitance and polarization when a constant current is applied in Example 1, and (b) shows the relationship between capacitance and polarization when a constant current is applied in Example 2. FIG. 3C is a diagram showing the relationship between capacitance and polarization when a constant current is applied to Comparative Example 1, and FIG. 3D is a diagram showing the relationship between capacitance and polarization when a constant current is applied to Comparative Example 2. It is a figure which shows the relationship of.

The monitoring method of the all-solid-state secondary battery, the power supply device, and the all-solid-state secondary battery will be described below with reference to the drawings. However, it should be noted that the technical scope of the present invention is not limited to those embodiments, but extends to the equivalent of the invention described in the claims.

(About the all-solid-state secondary battery related to the all-solid-state secondary battery according to the embodiment)
Before explaining the all-solid-state secondary battery according to the embodiment, the all-solid-state secondary battery related to the all-solid-state secondary battery according to the embodiment will be described.

FIG. 1A is a diagram showing a structure of an all-solid-state secondary battery related to the all-solid-state secondary battery according to the embodiment. FIG. 1 (b) is a diagram showing a change in potential with the negative electrode in the normal state of the all-solid secondary battery shown in FIG. 1 (a) as a reference potential, and FIG. 1 (c) is shown in FIG. 1 (a). It is a figure which shows the change of the potential with the negative electrode as a reference potential when the negative electrode and the positive electrode of an all-solid secondary battery are short-circuited. In FIGS. 1 (b) and 1 (c), the horizontal axis represents the distance from the end of the positive electrode, and the vertical axis represents the potential with the negative electrode as the reference potential in arbitrary units.

The all-solid-state secondary battery 100 has a negative electrode 101, which is also called a negative electrode layer, a positive electrode 102, which is also called a positive electrode layer, and a solid electrolyte 103, which is arranged between the negative electrode 101 and the positive electrode 102. The negative electrode 101 contains lithium titanate, titanium sulfide, lithium metal, lithium alloy, carbon and the like as the negative electrode active material. The positive electrode 102 uses lithium cobalt oxide, lithium nickel oxide, lithium manganate, lithium iron phosphate, lithium cobalt phosphate, lithium iron pyrophosphate, lithium cobalt pyrophosphate, lithium titanate, titanium sulfide, nickel sulfide and the like as positive electrodes. Contains as a substance. The solid electrolyte 103 contains LiPON (lithium oxynitride phosphate), Li ₇ La ₃ Zr ₂ O ₁₂ , Li _1.5 Al _0.5 G _e1.5 P ₃ O ₁₂ , Li _0.33 La _0.55 TiO _{3, and the} like. It is ideal that the areas of the front surface and the back surface of the negative electrode 101, the positive electrode 102, and the solid electrolyte 103 are equalized in that the members used can be minimized, but it is preferable that they are different in practical use. If the areas are different, the effective area becomes smaller and play occurs, but even if the position shift occurs during stacking, the effect can be tolerated, so that variation during mass production can be suppressed. The all-solid-state secondary battery 100 is charged and discharged via a positive electrode current collector and a negative electrode current collector (not shown) having aluminum, platinum, copper, or stainless steel.

If the all-solid-state secondary battery 100 is a thin film type, a positive electrode current collector, a positive electrode 102 having a positive electrode active material, a solid electrolyte 103, a negative electrode 101 having a negative electrode active material, and a negative electrode 101 having a negative electrode active material are placed on a substrate made of silicon or glass. It is formed by forming a vacuum in the order of the negative electrode current collector.

In the case of the bulk type, any one of the electrode, the solid electrolyte, and the current collector is used as a support substrate, and the other layers are formed on the support substrate by paste, sintering, pressing, or the like.

In an all-solid-state secondary battery, when Li metal is used as a negative electrode active substance, it is known that a phenomenon called dendrite, in which Li is precipitated in a branch shape in the solid electrolyte 103, occurs. The dendrite 104 grows from the negative electrode toward the positive electrode. The dendrite tends ^{to grow during charging when lithium ion Li +} flows from the positive electrode to the negative electrode, and is particularly likely to grow during rapid charging when a large current is applied. When the dendrite grows and reaches the positive electrode, a short circuit, also called a dendrite short circuit, occurs.

When a dendrite short circuit occurs, the positive electrode potential becomes substantially the same potential as the negative electrode potential as shown in FIG. 1 (c), so that the all-solid-state secondary battery may lose power and generate heat.

(Outline of all-solid-state secondary battery according to the embodiment)
Therefore, it is an object of the all-solid-state secondary battery according to the embodiment to provide an all-solid-state secondary battery capable of detecting a sign that a short circuit occurs between the negative electrode and the positive electrode. The all-solid-state secondary battery according to the embodiment is an intermediate capable of providing a solid electrolyte arranged between the negative electrode and the positive electrode and an ion species arranged inside the solid electrolyte and transferred between the negative electrode and the positive electrode. Includes layers. The all-solid-state secondary battery according to the embodiment can detect a sign that a short circuit occurs between the negative electrode and the positive electrode by detecting a decrease in internal resistance that occurs when the intermediate layer is short-circuited with the negative electrode. ..

(Structure of all-solid-state secondary battery according to the embodiment)
FIG. 2A is a diagram showing the structure of the all-solid-state secondary battery according to the embodiment. FIG. 2B is a diagram showing a change in potential with the negative electrode in the normal state of the all-solid secondary battery shown in FIG. 2A as a reference potential, and FIG. 2C is shown in FIG. 2A. It is a figure which shows the change of the potential with the negative electrode as a reference potential when the negative electrode and the intermediate layer of an all-solid secondary battery are short-circuited. In FIGS. 2 (b) and 2 (c), the horizontal axis represents the distance from the end of the positive electrode, and the vertical axis represents the potential with the negative electrode as the reference potential in arbitrary units.

The all-solid-state secondary battery 1 includes a negative electrode 11, a positive electrode 12, a first solid electrolyte 131, a second solid electrolyte 132, and an intermediate layer 14. Equalizing the front and back areas of the negative electrode 11, the positive electrode 12, the first solid electrolyte 131, the intermediate layer 14, and the second solid electrolyte 132 is ideal in that the members used can be minimized, but it is practically different. Better. If the areas are different, the effective area becomes smaller and play occurs, but even if the position shift occurs during stacking, the effect can be tolerated, so that variation during mass production can be suppressed. The negative electrode 11 contains lithium titanate, titanium sulfide, lithium metal, lithium alloy, carbon and the like as the negative electrode active material. The positive electrode 12 uses lithium cobalt oxide, lithium nickel oxide, lithium manganate, lithium iron phosphate, lithium cobalt phosphate, lithium iron pyrophosphate, lithium cobalt pyrophosphate, lithium titanate, titanium sulfide, nickel sulfide and the like as positive electrodes. Contains as a substance. Each of the first solid electrolyte 131 and the second solid electrolyte 132 contains LiPON, Li ₇ La ₃ Zr ₂ O ₁₂ , Li _1.5 Al _0.5 G _e1.5 P ₃ O ₁₂ , Li _0.33 La _0.55 TiO _{3, and the} like. The first solid electrolyte 131 is arranged between the negative electrode 11 and the intermediate layer 14, and the second solid electrolyte 132 is arranged between the positive electrode 12 and the intermediate layer 14. The thickness L1 of the first solid electrolyte 131 arranged between the negative electrode 11 and the intermediate layer 14 is equal to the thickness L2 of the second solid electrolyte 132 arranged between the positive electrode 12 and the intermediate layer 14.

^{The intermediate layer 14, which is an intermediate electrode, can provide lithium ion Li +} , which is an ion species transferred between the negative electrode 11 and the positive electrode 12, and is capable of ^{conducting both lithium ion Li +} and electrons. It is made of a property Li metal, Li alloy and Li compound. In one example, the intermediate layer 14 is formed of a lithium aluminum alloy, a lithium indium alloy, a lithium silicon alloy, a lithium tin alloy, or lithium carbide. The intermediate layer 14 is arranged between the first solid electrolyte 131 and the second solid electrolyte 132. When the intermediate layer 14 is not short-circuited with any of the electrodes of the negative electrode 11 and the positive electrode 12 ^{, the intermediate layer 14 functions as a conductor that conducts lithium ion Li +} , and no voltage drop occurs in the intermediate layer 14. That is, when the intermediate layer 14 is not short-circuited with either the negative electrode 11 or the positive electrode 12, the potential difference V between the negative electrode 11 and the positive electrode 12, _{the potential difference V 1 between the negative electrode 11 and the intermediate layer 14, and the positive electrode 12 The potential difference voltage V 2} between and the intermediate layer 14 is
V = V ₁ + V ₂ (1)
The relationship is shown. The intermediate layer 14 is arranged so that one surface faces the negative electrode 11 via the first solid electrolyte 131 and the other surface faces the positive electrode 12 via the second solid electrolyte 132.

Since the intermediate layer 14 has ^{biconductivity capable of conducting both lithium ion Li +} and electrons, it can function as a negative electrode when short-circuited with the negative electrode 11. That is, the intermediate layer 14 functions as a negative electrode when short-circuited with the negative electrode 11 to form an all-solid secondary battery in which the positive electrode 12 is the positive electrode and the second solid electrolyte 132 is the solid electrolyte.

Further, since the intermediate layer 14 is sandwiched between the first solid electrolyte 131 and the second solid electrolyte 132 in a normal state, lithium ion Li ⁺ is exchanged between the negative electrode 11 and the positive electrode 12. No electrons are exchanged between the negative electrode 11 and the positive electrode 12.

As shown in FIG. 2C, when the negative electrode 11 and the intermediate layer 14 are short-circuited, the negative electrode 11 has the same potential as the intermediate layer 14 and the first solid electrolyte 131 is inserted between the negative electrode 11 and the positive electrode 12. Form an all-solid-state secondary battery as a solid electrolyte. The solid electrolyte of the all-solid-state secondary battery formed between the negative electrode 11 and the intermediate layer 14 by short-circuiting between the negative electrode 11 and the positive electrode 12 is the second solid electrolyte 132. When the negative electrode 11 and the intermediate layer 14 are short-circuited, the negative electrode 11 and the intermediate layer 14 are short-circuited and the first solid electrolyte 131 does not function as a solid electrolyte, so that the thickness of the solid electrolyte is halved. As the thickness of the solid electrolyte is halved due to the short circuit between the negative electrode 11 and the intermediate layer 14, the magnitude of the internal resistance value of the all-solid-state secondary battery decreases, and the polarization due to the internal resistance decreases. The size decreases.

(Action and effect of the all-solid-state secondary battery according to the embodiment)
Since the all-solid-state secondary battery 1 has ^{an intermediate layer 14 having biconductivity capable of conducting both lithium ion Li +} and electrons between the negative electrode 11 and the positive electrode 12, between the negative electrode 11 and the intermediate layer 14. Can operate as an all-solid-state secondary battery even if is short-circuited.

Further, the all-solid-state secondary battery 1 can detect a decrease in internal resistance from a decrease in polarization when a short circuit occurs between the negative electrode 11 and the intermediate layer 14. The all-solid-state secondary battery 1 detects a decrease in internal resistance when either one of the negative electrode 11 and the positive electrode 12 and the intermediate layer 14 are short-circuited, so that a complete short circuit between the negative electrode and the positive electrode can be achieved. It is possible to detect signs of occurrence.

FIG. 3A is a diagram showing a change in the potential difference between the negative electrode and the positive electrode when the negative electrode 11 and the intermediate layer 14 are short-circuited during charging in the all-solid-state secondary battery 1 according to the embodiment. is there. FIG. 3B is a diagram showing a change in the potential difference between the negative electrode and the positive electrode when the negative electrode 101 and the positive electrode 102 are short-circuited during charging in the conventional all-solid-state secondary battery 100. In FIGS. 3 (a) and 3 (b), the horizontal axis represents the charging time, and the vertical axis represents the potential difference between the negative electrode and the positive electrode.

The all-solid-state secondary battery 1 according to the embodiment continues to be charged while maintaining the function as an all-solid-state secondary battery when the negative electrode 11 and the intermediate layer 14 are short-circuited at the time indicated by the arrow A. .. In the all-solid-state secondary battery 1 according to the embodiment, when the negative electrode 11 and the intermediate layer 14 are short-circuited, a voltage drop corresponding to a decrease in polarization, which is indicated by a bidirectional arrow B in FIG. 3A, occurs. appear. In the all-solid-state secondary battery 1 according to the embodiment, a voltage drop occurs in response to a short circuit between the negative electrode 11 and the intermediate layer 14, so that any one of the negative electrode 11 and the positive electrode 12 and the intermediate layer 14 are separated from each other. It is possible to detect that a short circuit has occurred.

In the conventional all-solid-state secondary battery 100, when the negative electrode 101 and the positive electrode 102 are short-circuited at the time indicated by the arrow C, the potentials between the negative electrode 101 and the positive electrode 102 are substantially the same, so that the potential difference before the short circuit occurs. There is a risk that the energy of the minute will be released rapidly and heat will be generated.

(Configuration and function of the power supply unit including the all-solid-state secondary battery according to the embodiment)
FIG. 4 is a circuit block diagram of a power supply unit including the all-solid-state secondary battery 1. In FIG. 4, the control wiring is indicated by an alternate long and short dash line.

The power supply unit 20 includes an all-solid-state secondary battery 1, a first switch 21, a second switch 22, a power supply control device 23, and a power supply monitoring device 24. The power supply unit 20 charges the all-solid-state secondary battery 1 with the input power applied between the first input terminal Tin1 and the second input terminal Tin2 from the power supply source 31. Further, the power supply unit 20 discharges the electric power charged in the all-solid-state secondary battery 1 to the load discharge circuit 32 connected between the first output terminal Tout1 and the second output terminal Tout2. Further, the power supply unit 20 diagnoses the deterioration of the all-solid-state secondary battery 1 and detects the presence or absence of a sign of a short circuit between the negative electrode 11 and the positive electrode 12 of the all-solid-state secondary battery 1.

Each of the first switch 21 and the second switch 22 has a connection relationship between the all-solid-state secondary battery 1 and the power supply source 31 and the load discharge circuit 32 according to the control signal input from the power supply control device 23. To switch.

FIG. 5A is a diagram showing a switching state of the first switch 21 and the second switch 22 when charging the all-solid-state secondary battery 1, and FIG. 5B is a diagram showing the switching state of the all-solid-state secondary battery 1 and discharging the all-solid-state secondary battery 1. It is a figure which shows the switching state of the 1st switch 21 and the 2nd switch 22 at the time.

When charging the all-solid secondary battery 1, the first switch 21 and the second switch 22 electrically connect the all-solid secondary battery 1 and the power supply source 31 to form the all-solid secondary battery 1. And the load discharge circuit 32 are electrically cut off. When charging the all-solid-state secondary battery 1, the charging current Ic flows from the power supply source 31 to the all-solid-state secondary battery 1. On the other hand, when the all-solid secondary battery 1 is discharged, the first switch 21 and the second switch 22 electrically cut off between the all-solid secondary battery 1 and the power supply source 31, and the all-solid secondary battery 1 is discharged. The battery 1 and the load discharge circuit 32 are electrically connected. When the all-solid-state secondary battery 1 is discharged, the discharge current Id flows from the all-solid-state secondary battery 1 to the load discharge circuit 32 via the second switch 22.

Further, when the charging / discharging of the all-solid-state secondary battery 1 is stopped, the first switch 21 and the second switch 22 electrically connect the all-solid-state secondary battery 1 with the power supply source 31 and the load discharge circuit 32. Cut off.

The power supply control device 23 switches the connection state of the first switch 21 and the second switch 22 according to the switching instruction signal input from the power supply monitoring device 24.

The power supply monitoring device 24 has a storage unit that stores a computer program and a storage unit, and a calculation unit that executes a predetermined process based on the computer program stored in the storage unit. Further, the power supply monitoring device 24 includes a DC voltmeter capable of measuring the potential difference between the negative electrode 11 and the positive electrode 12 of the all-solid secondary battery 1, a charging current Ic flowing through the all-solid secondary battery 1, and an all-solid secondary battery. It further has a DC current meter capable of measuring both the discharge current Id flowing from 1. Further, the power supply monitoring device 24 further includes an internal resistance measuring device for measuring the internal resistance value of the all-solid-state secondary battery 1 by passing an alternating current of about 1 kHz through the all-solid-state secondary battery 1. An example of the power supply monitoring device 24 is shown in Non-Patent Document 1.

The power supply monitoring device 24 outputs a switching instruction signal to the power supply control device 23 in response to an instruction to charge the all-solid-state secondary battery 1 and an instruction to discharge the all-solid-state secondary battery 1. The instruction to charge the all-solid-state secondary battery 1 and the instruction to discharge the all-solid-state secondary battery 1 are input from a higher-level control device (not shown). Further, the power supply monitoring device 24 switches to indicate the stop of charging / discharging of the all-solid-state secondary battery 1 when a short circuit occurs between either one of the negative electrode 11 and the positive electrode 12 of the all-solid-state secondary battery 1 and the intermediate layer 14. The signal is output to the power supply control device 23.

(Battery monitoring process by the power supply unit according to the embodiment)
FIG. 6 is a flowchart of the battery monitoring process by the power supply unit 20. The battery monitoring process shown in FIG. 6 is executed mainly by the arithmetic unit of the power supply monitoring device 24 in cooperation with each element of the power supply unit 20 based on a program stored in advance in the storage unit of the power supply monitoring device 24. To. The battery monitoring process shown in FIG. 6 is executed by interrupts at predetermined time intervals in the power supply monitoring device 24.

First, the power supply monitoring device 24 measures the internal resistance value of the all-solid-state secondary battery 1 (S101), and determines whether or not the internal resistance value measured in the process of S101 is equal to or less than the first threshold value (S102). ). In general, the internal resistance value of a lithium ion secondary battery tends to increase as the deterioration over time progresses. The first threshold value is a first threshold value for determining the amount of increase in the internal resistance value of the all-solid-state secondary battery 1 due to aged deterioration. When the power supply monitoring device 24 determines that the internal resistance value measured in the process of S101 is larger than the first threshold value (S102-NO), is the internal resistance value measured in the process of S101 equal to or less than the second threshold value? It is determined whether or not (S103). The second threshold value is a second threshold value for determining the amount of increase in the internal resistance value of the all-solid-state secondary battery 1 due to aged deterioration, and is a value even larger than the first threshold value. When the power supply monitoring device 24 determines that the internal resistance value measured in the process of S101 is equal to or less than the second threshold value (S103-YES), it indicates that the aged deterioration of the all-solid-state secondary battery 1 is progressing. A deterioration caution signal is output to a higher-level control device (not shown) (S104). Further, when the power supply monitoring device 24 determines that the internal resistance value measured in the process of S101 is larger than the second threshold value (S103-NO), the aged deterioration of the all-solid-state secondary battery 1 is further progressing. Is output to a higher-level control device (not shown). The operator may replace the all-solid-state secondary battery 1 after confirming that the deterioration alarm signal has been input to the higher-level control device (not shown).

When the power supply monitoring device 24 determines that the internal resistance value measured in the process of S101 is equal to or less than the first threshold value (S102-YES), the internal resistance value measured in the process of S101 is equal to or greater than the third threshold value. Whether or not it is determined (S106). The third threshold value is a threshold value for determining the amount of decrease in the internal resistance value of the all-solid-state secondary battery 1 due to a short circuit between the negative electrode 11 or the positive electrode 12 and the intermediate layer 14, and the first threshold value and It is a value smaller than the second threshold value.

When the power supply monitoring device 24 determines that the internal resistance value measured in the process of S101 is smaller than the third threshold value (S106-NO), the short-circuit sign signal indicating that the all-solid-state secondary battery 1 has a short-circuit sign. Is output to a higher-level control device (not shown) (S107). Next, the power supply monitoring device 24 outputs a switching signal indicating the stop of charging / discharging of the all-solid-state secondary battery 1 to the power supply control device 23. The power supply control device 23 sets the first switch 21 and the second switch 22 to the all-solid-state secondary battery 1 and the power supply source in response to the input of the switching signal indicating the stop of charging / discharging of the all-solid-state secondary battery 1. It is switched so as to electrically cut off between 31 and the load discharge circuit 32.

(Action and effect of the power supply unit according to the embodiment)
In the power supply unit 20, the power supply control device 23 detects a decrease in the internal resistance value due to a short circuit between the negative electrode 11 and the positive electrode 12 of the all-solid-state secondary battery 1 and the intermediate layer 14, and the negative electrode 11 It is possible to detect a sign that a short circuit occurs between the positive electrode 12 and the positive electrode 12.

Further, in the power supply unit 20, the power supply control device 23 can detect a sign of a short circuit when the all-solid-state secondary battery 1 is being charged or discharged, so that a dendrite short circuit is likely to occur during rapid charging. However, it is possible to detect signs that a short circuit will occur.

Further, in the power supply unit 20, the power supply control device 23 can detect a short circuit between the negative electrode 11 and the intermediate layer 14 before the negative electrode 11 and the positive electrode 12 of the all-solid-state secondary battery 1 are completely short-circuited. , It is possible to shorten the equipment outage period due to power loss.

(Modification example of power supply unit according to the embodiment)
The all-solid-state secondary battery 1 is a lithium-ion secondary battery having lithium ion Li ⁺ as an ionic species, but the all-solid-state secondary battery according to the embodiment has another alkali metal ion such as sodium ion as an ionic species. It may be an all-solid-state secondary battery.

In the all-solid-state secondary battery 1, the thickness of the first solid electrolyte 131 is equal to the thickness of the second solid electrolyte 132, but in the all-solid-state secondary battery according to the embodiment, the thickness of the solid electrolyte sandwiching the intermediate layer. May be different.

Further, in the power supply unit 20, the power supply monitoring device 24 applies an alternating current to measure the internal resistance value of the all-solid-state secondary battery 1, but in the power supply unit according to the embodiment, the power supply monitoring device has a reduced capacity and a decrease in capacity. Other means capable of detecting deterioration phenomena such as an increase in internal resistance may be adopted. For example, the power supply monitoring device may detect the deterioration phenomenon of the all-solid-state secondary battery 1 based on the output such as the output current and the output voltage of the all-solid-state secondary battery 1.

(Example)
FIG. 7 (a) is a diagram showing the structure of the all-solid-state secondary battery according to the embodiment, and FIG. 7 (b) is a perspective view of the all-solid-state secondary battery shown in FIG. 7 (a). FIG. 8A is a diagram showing the structure of the all-solid-state secondary battery according to the comparative example, and FIG. 8B is a side view of the all-solid-state secondary battery shown in FIG. 8A.

(Structure of Example)
Both Example 1 and Example 2 have the structure shown below. Since the active material of the working electrode corresponding to the positive electrode and the active material of the counter electrode corresponding to the negative electrode are both Li metals, no electromotive force is generated due to the potential difference between the positive electrode active material and the negative electrode active material, and the potential difference due to polarization is measured. To.
Working electrode (positive electrode): Active substance Li metal, caliber 6 mm, thickness 0.6 mm
Second solid electrolyte: Solid electrolyte Li ₇ La ₃ Zr ₂ O ₁₂ , 10 mm square, 1 mm thick
Intermediate layer: Active substance Li metal, caliber 6 mm, thickness 0.6 mm
First solid electrolyte: Solid electrolyte Li ₇ La ₃ Zr ₂ O ₁₂ , 10 mm square, 1 mm thick
Counter electrode (negative electrode): Active substance Li metal, caliber 8 mm, thickness 0.6 mm

(Structure of comparative example)
As shown below, the working poles and counter poles of Comparative Examples 1 and 2 have the same structure as the working poles and counter poles of Examples 1 and 2. Further, the solid electrolytes of Comparative Example 1 and Comparative Example 2 had the same structure as the first solid electrolyte and the second solid electrolyte of Examples 1 and 2, respectively.
Working electrode (positive electrode): Active substance Li metal, caliber 6 mm, thickness 0.6 mm
Solid electrolyte: Solid electrolyte Li ₇ La ₃ Zr ₂ O ₁₂ , 10 mm square, 1 mm thick
Counter electrode (negative electrode): Active substance Li metal, caliber 8 mm, thickness 0.6 mm

(Energization of Examples and Comparative Examples)
In Examples 1 and 2, a constant current was applied in the direction in which the Li metal was deposited on the working electrode. ^{A constant current of 0.5 mA / cm 2} was applied to Example 1, Comparative Example 1 and Comparative Example 2, and a constant current of 0.3 mA / cm ² was applied to Example 2. In Examples 1 and 2, a constant current was applied until the counter electrode and the intermediate layer were short-circuited and then the working electrode and the counter electrode were short-circuited. In Comparative Example 1 and Comparative Example 2, a constant current was passed until the working electrode and the counter electrode were short-circuited.

FIG. 9A is a diagram showing the relationship between capacitance and polarization when a constant current is applied in Example 1, and FIG. 9B is a diagram showing the relationship between capacitance and polarization when a constant current is applied in Example 2. It is a figure which shows the relationship of. FIG. 9 (c) is a diagram showing the relationship between the capacitance and polarization when a constant current is applied in Comparative Example 1, and FIG. 9 (d) is a diagram showing the capacitance and polarization when a constant current is applied in Comparative Example 2. It is a figure which shows the relationship of.

Table 1 shows, in each of Examples 1 and 2, the first capacitance A when the working electrode or the counter electrode and the intermediate layer are short-circuited, and the second capacitance A when the working electrode and the counter electrode are short-circuited. The relationship between the capacity B and (second capacity B-1st capacity A) / first capacity A is shown.

The ratio of the difference between the second capacitance B when the working electrode and the counter electrode are short-circuited and the first capacitance A when the working electrode or the counter electrode and the intermediate layer is short-circuited with respect to the first capacitance A is an embodiment. In 1, it was 21%, and in Example 2, it was 6.3%. In both Examples 1 and 2, by detecting a decrease in internal resistance from the polarization corresponding to the second capacitance B, it is possible to detect a sign of a short circuit between the working electrode and the counter electrode.

On the other hand, in Comparative Example 1, when the capacitance was 13.1 μAh, the working electrode and the counter electrode were short-circuited, and in Comparative Example 2, when the capacitance was 11.2 μAh, the working electrode and the counter electrode were short-circuited. Since neither Comparative Example 1 nor Comparative Example 2 has an intermediate layer, it is not possible to detect a sign of a short circuit between the working electrode and the counter electrode.

1 All-solid-state secondary battery 11 Negative electrode 12 Positive electrode 131 First solid electrolyte 132 Second solid electrolyte 14 Intermediate layer 20 Power supply unit (power supply device)
21 1st switch 22 2nd switch 23 Power supply control device 24 Power supply monitoring device

Claims (5)

An alkali metal ion which is an ion species arranged between a negative electrode, a positive electrode, a solid electrolyte arranged between the negative electrode and the positive electrode, and between the solid electrolyte and between the negative electrode and the positive electrode. The solid electrolyte has an intermediate layer having biconductivity capable of conducting both the alkali metal ion and the electron, and the solid electrolyte is arranged between the negative electrode and the intermediate layer. The output of an all-solid secondary battery having a first solid electrolyte containing alkali metal ions and a second solid electrolyte disposed between the positive electrode and the intermediate layer and containing the alkali metal ions was measured.
Based on the measured output, the presence or absence of a short circuit between the negative electrode and the intermediate layer is determined.
When it is determined that a short circuit has occurred between the negative electrode and the intermediate layer, a short circuit sign signal indicating that the all-solid-state secondary battery has a short circuit sign is output.
All-solid-state secondary battery monitoring methods, including that. With the negative electrode
With the positive electrode
A solid electrolyte disposed between the negative electrode and the positive electrode,
Alkali metal ions, which are ionic species arranged between the solid electrolytes and transferred between the negative electrode and the positive electrode, can be provided , and both the alkali metal ions and electrons can be conducted. With an intermediate layer, and
The solid electrolyte is
A first solid electrolyte disposed between the negative electrode and the intermediate layer and containing the alkali metal ion,
A second solid electrolyte disposed between the positive electrode and the intermediate layer and containing the alkali metal ion,
With an all-solid-state secondary battery,
A power supply monitoring device that detects a short circuit between the negative electrode and the intermediate layer and detects a sign of a short circuit of the all-solid-state secondary battery.
Power supply with. The power supply device according to claim 2, wherein the intermediate layer functions as a negative electrode when short-circuited with the negative electrode. Claim 2 or 3 wherein the intermediate layer contains any of a monometal, an alloy or a compound having biconductivity capable of providing the alkali metal ion and conducting both the alkali metal ion and an electron. The power supply described in. Before Kia alkali metal ions are lithium ion power supply apparatus according to any one of claims 2-4.

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