Patent Publication Number: US-2022231539-A1

Title: Wireless rechargeable solid-state battery module

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims benefit of priority to International Patent Application No. PCT/JP2020/023356, filed Jun. 15, 2020, and to Japanese Patent Application No. 2019-188229, filed Oct. 11, 2019, the entire contents of each are incorporated herein by reference. 
    
    
     BACKGROUND 
     Technical Field 
     The present disclosure relates to a module including a solid-state battery. 
     Background Art 
     Japanese Patent No. 5798407 suggests a non-contact charging type secondary battery in which a secondary battery and a wireless power transmission circuit are provided in a casing. In specific, the non-contact charging type secondary battery includes: an alkaline secondary battery; a power receiving circuit including power receiving coils and a resonant capacitor connected to the power receiving coils in parallel and receiving alternate current power via a magnetic field from a power transmission device; a rectifier circuit for rectifying alternate current power received by the power receiving circuit; a current limit circuit for limiting a charging current from the rectifier circuit to the alkaline secondary battery; and an external body having a columnar shape and containing a positive electrode terminal and a negative electrode terminal that are connected to the alkaline secondary battery. The configuration is described in which the power receiving coils are provided along an inner circumferential surface of the external body. 
     SUMMARY 
     The non-contact charging type secondary battery described in Japanese Patent No. 5798407 is assumed to be an alkaline secondary battery that has a cylindrical casing and is substitutable for a dry cell battery. Such a non-contact charging type secondary battery cannot be downsized and is hard to be mounted on a small device such as a wearable device. 
     On the other hand, as a device is smaller such as a hearing aid, it becomes harder to handle a battery as a single body. Therefore, highly-flexible charging is desired to be achieved. 
     For this reason, the present disclosure provides a down-sized wireless rechargeable solid-state battery module that is capable of performing wireless charging in any state of being single, being mounted on a circuit board, and being mounted on a device. 
     A wireless rechargeable solid-state battery module as an example of the present disclosure includes a solid-state battery; an internal structure that is provided with an internal circuit electrically connected with the solid-state battery; a positive electrode terminal and a negative electrode terminal each of which is electrically connected with the solid-state battery, is exposed on an outer surface, and is arranged so that the positive electrode terminal or the negative electrode terminal can be mounted on a mounting board; and a barrier layer that isolates the solid-state battery from an outside air environment. The internal circuit includes a wireless charging circuit that receives power from an outside via a power transmission magnetic field and controls charging to the solid-state battery. 
     According to the present disclosure, a wireless rechargeable solid-state battery module is obtained that is capable of performing wireless charging in any state of being single, being mounted on a circuit board, and being mounted on a device. 
     The electronic circuit board on which the wireless rechargeable solid-state battery module according to the present disclosure is mounted can receive power from the outside via an electromagnetic field or a magnetic field produced by power transmission from the outside, with the wireless rechargeable solid-state battery module. This eliminates a need for configuring a wireless charging circuit on the electronic circuit board. Further, a solid-state battery and a wireless charging circuit can be mutually connected with short wiring, being able to reduce power loss in wiring and suppress malfunction caused by an external magnetic field. Furthermore, reduction in size, weight, and thickness and higher efficiency of the mounting electronic circuit board can be achieved. Also, the mounting electronic circuit board itself can be used as a mounting electronic circuit board provided with an all-solid-state battery and having a wireless charging function, being able to achieve reduction in size and weight and higher efficiency in electronic and electrical devices. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a sectional view of a wireless rechargeable solid-state battery module according to a first embodiment; 
         FIG. 2  is a sectional view illustrating a basic configuration of a solid-state battery according to the first embodiment; 
         FIG. 3  is a plan view illustrating a configuration of a power receiving coil; 
         FIG. 4  is a bottom view of the wireless rechargeable solid-state battery module; 
         FIG. 5  is a circuit diagram of the wireless rechargeable solid-state battery module; 
         FIG. 6  is a perspective view illustrating an example of a state in which the wireless rechargeable solid-state battery module is mounted on a mounting board and a positional relation with respect to a power transmission coil of a power transmission device; 
         FIG. 7  is a perspective view illustrating another example of a state in which the wireless rechargeable solid-state battery module is mounted on the mounting board and a positional relation with respect to a power transmission device; 
         FIG. 8  is a perspective view illustrating a state in which a power transmission device transmits power to a plurality of wireless rechargeable solid-state battery modules; 
         FIG. 9  is a sectional view of another wireless rechargeable solid-state battery module according to the first embodiment; 
         FIG. 10  is a circuit diagram of a wireless rechargeable solid-state battery module according to a second embodiment; 
         FIG. 11  is a circuit diagram of a wireless rechargeable solid-state battery module according to a third embodiment; 
         FIG. 12  is a circuit diagram of a wireless rechargeable solid-state battery module according to a fourth embodiment; 
         FIG. 13  is a circuit diagram of a wireless rechargeable solid-state battery module and the like according to a fifth embodiment; 
         FIGS. 14A, 14B, 14C, and 14D  are circuit diagrams illustrating specific examples of a power reception protection circuit; 
         FIG. 15  is another circuit diagram of the wireless rechargeable solid-state battery module and the like; 
         FIGS. 16A and 16B  are diagrams for explaining an operation of a cutoff circuit in normal power-reception time; 
         FIGS. 17A and 17B  are diagrams for explaining an operation of the cutoff circuit in a state in which a received voltage exceeds a specified value; 
         FIGS. 18A and 18B  are diagrams illustrating configuration examples of a received voltage detection circuit illustrated in  FIG. 15 ; 
         FIG. 19  is a circuit diagram illustrating a specific example of a protection circuit; 
         FIG. 20  is a diagram illustrating a configuration of a cutoff circuit of a wireless rechargeable solid-state battery module according to a sixth embodiment; 
         FIG. 21  is a diagram illustrating a configuration of a cutoff circuit of another wireless rechargeable solid-state battery module according to the sixth embodiment; 
         FIG. 22  is a circuit diagram partially illustrating a wireless rechargeable solid-state battery module and a power transmission device according to a seventh embodiment; and 
         FIG. 23  is a circuit diagram partially illustrating another wireless rechargeable solid-state battery module and a power transmission device according to an seventh embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, a plurality of embodiments for carrying out the present disclosure will be described with some specific examples referring to the accompanying drawings. The same reference characters are given to the same components among the drawings. For convenience of explanation of the embodiments, description will be provided separately in a plurality of embodiments so as to focus on explaining main points or facilitating understanding, but it is possible to make partial replacement or combination of configurations described in different embodiments. The second and following embodiments will omit the description of matters common to those of the first embodiment and describe only different points. In particular, the same advantageous effects obtained with the same configurations will not be sequentially mentioned in each embodiment. 
     First Embodiment 
       FIG. 1  is a sectional view of a wireless rechargeable solid-state battery module  101  according to a first embodiment. The wireless rechargeable solid-state battery module  101  includes a solid-state battery  1 , internal structures  11  and  12 , barrier layers  14 , a positive electrode terminal E 3 , and a negative electrode terminal E 5 . The barrier layers  14  isolate the solid-state battery  1  from the outside air environment. Each of the positive electrode terminal E 3  and the negative electrode terminal E 5  is electrically connected with the solid-state battery  1  and is exposed on an outer surface of the wireless rechargeable solid-state battery module  101 . 
     The internal structures  11  and  12  are arranged on positions sandwiching the solid-state battery  1  in a laminating direction thereof, and the internal structures  11  and  12  are overlapped with the solid-state battery  1  when viewed in this laminating direction. The internal structures  11  and  12  are provided with an internal circuit that is electrically connected with the solid-state battery  1 . On the both surfaces of each of the internal structures  11  and  12 , the barrier layers  14  are respectively provided. A magnetic layer  16  is provided on a lower surface (a surface on the solid-state battery  1  side) of the internal structure  12 . 
     The positive electrode terminal E 3  and the negative electrode terminal E 5  are arranged together with other terminals so as to be able to be mounted on a mounting board  80 . That is, the positive electrode terminal E 3  and the negative electrode terminal E 5  are arranged on a surface (lower surface) facing the mounting board  80 . On the mounting board  80 , a circuit using the wireless rechargeable solid-state battery module  101  as a power supply module is configured. 
     The internal circuit mentioned above includes a wireless charging circuit that receives power from the outside via a power transmission magnetic field and controls charging to the solid-state battery  1 . 
     A buffer layer  15  is formed between the upper surface of the internal structure  12  and the barrier layer  14 . The buffer layer  15  suppresses peeling of the barrier layer  14 . 
     The internal structure  11  is composed of a first circuit board  20  on which a plurality of electronic components are mounted, and the internal structure  12  is composed of a second circuit board  30  on which a plurality of electronic components are mounted. The first circuit board  20  and the second circuit board  30  are positioned to sandwich the solid-state battery  1  in the laminating direction. 
     The solid-state battery  1  is a battery which has a rectangular parallelepiped outer shape, and in the direction shown in  FIG. 1 , a positive electrode  1 P and a negative electrode  1 N are respectively formed on the left side surface and the right side surface. The periphery of the solid-state battery  1  is filled with a mold resin portion  13  in a state in which the solid-state battery  1  is interposed between the first circuit board  20  and the second circuit board  30 . The mold resin portion  13  is made of polyimide, for example, and enhances impact resistance of the solid-state battery  1 . The mold resin portion  13  corresponds to an “impact absorbing member” according to the present disclosure. 
     The first circuit board  20  is a low temperature co-fired ceramics (LTCC) board, for example. Alternatively, a high temperature co-fired ceramics (HTCC) board may be employed. As merely an example, the thickness of the first circuit board  20  may be from 20 μm to 1000 μm inclusive and is, for example, from 100 μm to 300 μm inclusive. 
     Electronic components  23   a  and  23   b  and the like are mounted on an inner surface (a surface on the solid-state battery  1  side) of the first circuit board  20 . 
     The second circuit board  30  is, for example, a polyimide (PI)-based or polyethylene terephthalate (PET)-based flexible board, or a liquid crystal polymer (LCP)-based flexible resin board. As merely an example, the thickness of the second circuit board  30  may be from 20 μm to 1000 μm inclusive and is, for example, from 100 μm to 300 μm inclusive. 
     On an outer surface (an opposite surface to a surface facing the solid-state battery  1 ) of the second circuit board  30 , a power receiving coil  31  and the like are formed. Electronic components  33   a  and  33   b  and the like such as a DC-DC converter IC and a capacitor are mounted on the outer surface of the second circuit board  30 . On this second circuit board  30 , the power receiving coil  31 , a rectifier circuit  52 , and a DC-DC converter  54 , which are illustrated in  FIG. 5 , are configured. Other circuit units are configured on the first circuit board  20 . 
     The magnetic layer  16  acts as a magnetic path for a magnetic flux passing through a coil opening of the power receiving coil  31  and acts as a shielding member that magnetically shields the solid-state battery  1 . The provision of the magnetic layer  16  facilitates magnetic field coupling between the power receiving coil  31  and a power transmission coil of a power transmission device. Further, it is possible to suppress eddy current generated in a conductor portion of the solid-state battery  1  in reception of a magnetic field from the power transmission coil. 
     Between the first circuit board  20  and the second circuit board  30 , wirings  7 A and  7 B are formed. The wirings  7 A and  7 B are conductor portions obtained by Ag paste printing. An interval between the first circuit board  20  and the second circuit board  30  may be, for example, from 3 mm to 10 mm inclusive and is, for example, 5 mm. 
     On lateral surfaces of the wireless rechargeable solid-state battery module  101 , metal thin films  4  such as copper foils are formed in a film coating manner. 
     The positive electrode terminal E 3  and the negative electrode terminal E 5  that are formed on the outer surface (lower surface) of the first circuit board  20  are connected to a pad electrode, which is formed on the mounting board  80 , via solder or the like. The wireless rechargeable solid-state battery module  101  is thus surface-mounted on the mounting board  80 . 
     The “solid-state battery” in the present disclosure indicates a battery whose components are made of solids in a broad sense, and indicates an all-solid-state battery whose components (especially preferably all components) are made of solids in a narrow sense. In a favorable aspect, the solid-state battery of the present disclosure is a laminate type solid-state battery configured so that layers serving as battery constituting units are mutually laminated, and each of the layers is preferably made of a sintered body. 
       FIG. 2  is a sectional view illustrating a basic configuration of the solid-state battery  1  according to the present embodiment. The configuration of the solid-state battery described here is merely an example for facilitating understanding of the disclosure and does not limit the disclosure. 
     [Basic Configuration of Solid-State Battery] 
     As illustrated in  FIG. 2 , the solid-state battery  1  has a solid-state battery multilayer body in which a plurality of battery constituting units, each of which includes a positive electrode layer  110 , a negative electrode layer  120 , and solid electrolyte  130 , are laminated. 
     The layers constituting the solid-state battery  1  are formed by firing and the solid-state battery  1  includes sintered layers such as the positive electrode layer  110 , the negative electrode layer  120 , and the solid electrolyte  130 . The positive electrode layer  110 , the negative electrode layer  120 , and the solid electrolyte  130  are preferably integrally fired. 
     The positive electrode layer  110  is an electrode layer containing at least a positive electrode active material. The positive electrode layer  110  may further contain solid electrolyte. In a favorable aspect, the positive electrode layer  110  is composed of a sintered body that contains at least positive electrode active material particles and solid electrolyte particles. On the other hand, the negative electrode layer  120  is an electrode layer containing at least a negative electrode active material. The negative electrode layer  120  may further contain solid electrolyte. In a favorable aspect, the negative electrode layer  120  is composed of a sintered body that contains at least negative electrode active material particles and solid electrolyte particles. 
     The positive electrode active material and the negative electrode active material are substances involved in electron transfer in the solid-state battery. The electron transfer is performed in a manner such that ions move (conduct) between the positive electrode layer  110  and the negative electrode layer  120  via the solid electrolyte. Charge/discharge is thus performed. The positive electrode layer  110  and the negative electrode layer  120  are preferably layers that can occlude and release especially lithium ions. That is, the solid-state battery is preferably an all-solid-state secondary battery in which lithium ions move between the positive electrode layer  110  and the negative electrode layer  120  via the solid electrolyte to perform charge/discharge of the battery. 
     &lt;Positive Electrode Active Material&gt; 
     The positive electrode active material contained in the positive electrode layer  110  is at least one selected from the group consisting of a lithium-containing phosphoric acid compound having a nasicon-type structure, a lithium-containing phosphoric acid compound having an olivine-type structure, lithium-containing layered oxide, lithium-containing oxide having a spinel-type structure, and the like, for example Examples of the lithium-containing phosphoric acid compound having a nasicon-type structure include Li 3 V 2 (PO 4 ) 3 . Examples of the lithium-containing phosphoric acid compound having an olivine-type structure include Li 3 Fe 2 (PO 4 ) 3 , LiFePO 4 , and LiMnPO 4 . Examples of the lithium-containing layered oxide include LiCoO 2  and LiCo 1/3 Ni 1/3 Mn 1/3 O 2 . Examples of the lithium-containing oxide having a spinel-type structure include LiMn 2 O 4  and LiNi 0.5 Mn 1.5 O 4 . 
     &lt;Negative Electrode Active Material&gt; 
     The negative electrode active material contained in the negative electrode layer  120  is at least one selected from the group consisting of oxide containing at least one element selected from the group consisting of Ti, Si, Sn, Cr, Fe, Nb, and Mo, a graphite-lithium compound, a lithium alloy, a lithium-containing phosphoric acid compound having a nasicon-type structure, a lithium-containing phosphoric acid compound having an olivine-type structure, lithium-containing oxide having a spinel-type structure, and the like, for example. Examples of the lithium alloy include Li—Al. Examples of the lithium-containing phosphoric acid compound having a nasicon-type structure include Li 3 V 2 (PO 4 ) 3  and LiTi 2 (PO 4 ) 3 . Examples of the lithium-containing phosphoric acid compound having an olivine-type structure include Li 3 Fe 2 (PO 4 ) 3  and LiCuPO 4 . Examples of the lithium-containing oxide having a spinel-type structure include Li 4 Ti 5 O 12 . 
     One or both of the positive electrode layer  110  and the negative electrode layer  120  may contain a conductive aid. The conductive aid contained in the positive electrode layer  110  and the negative electrode layer  120  can be at least one material that contains: a metal material such as silver, palladium, gold, platinum, aluminum, copper, and nickel; carbon; and the like. Not especially limited, copper is favorable on the point that copper does not easily react with the positive electrode active material, the negative electrode active material, the solid electrolyte material, and the like and is effective in reducing internal resistance of the solid-state battery. 
     Further, one or both of the positive electrode layer  110  and the negative electrode layer  120  may contain a sintering aid. The sintering aid can be at least one selected from the group consisting of lithium oxide, sodium oxide, potassium oxide, boron oxide, silicon oxide, bismuth oxide, and phosphorus oxide. 
     &lt;Solid Electrolyte&gt; 
     The solid electrolyte  130  is a material that can conduct lithium ions. Especially, the solid electrolyte  130  serving as a battery constituting unit in the solid-state battery is a layer that can conduct lithium ions between the positive electrode layer  110  and the negative electrode layer  120 . Specific examples of the solid electrolyte  130  include lithium-containing phosphoric acid compound having a nasicon structure, oxide having a perovskite structure, and oxide having a garnet-type or a garnet-type-like structure. Examples of the lithium-containing phosphoric acid compound having a nasicon structure include Li x M y (PO 4 ) 3  (1≤x≤2, 1≤y≤2, M is at least one selected from the group consisting of Ti, Ge, Al, Ga, and Zr). Examples of the lithium-containing phosphoric acid compound having a nasicon structure include Li 1.2 Al 0.2 Ti 1.8 (PO 4 ) 3 . Examples of the oxide having a perovskite structure include La 0.55 Li 0.35 TiO 3 . Examples of the oxide having a garnet-type or a garnet-type-like structure include Li 7 La 3 Zr 2 O 12 . 
     The solid electrolyte  130  may contain a sintering aid. The sintering aid contained in the solid electrolyte  130  may be selected from the same materials as those of sintering aids that can be contained in the positive electrode layer  110  and the negative electrode layer  120 , for example. 
     &lt;Positive Electrode Current Collector Layer and Negative Electrode Current Collector Layer&gt; 
     The positive electrode layer  110  and the negative electrode layer  120  may respectively include a positive electrode current collector layer and a negative electrode current collector layer. Each of the positive electrode current collector layer and the negative electrode current collector layer may have a foil shape. However, from the viewpoints of reduction in manufacturing cost of a solid-state battery through integral firing and reduction in internal resistance of the solid-state battery, the positive electrode current collector layer and the negative electrode current collector layer may have a shape of a sintered body. When the positive electrode current collector layer and the negative electrode current collector layer have the shape of a sintered body, the positive electrode current collector layer and the negative electrode current collector layer may be composed of a sintered body containing a conductive aid and a sintering aid. The conductive aid contained in the positive electrode current collector layer and the negative electrode current collector layer may be selected from the same materials as those of conductive aids that can be contained in the positive electrode layer  110  and the negative electrode layer  120 , for example. The sintering aid contained in the positive electrode current collector layer and the negative electrode current collector layer may be selected from the same materials as those of sintering aids that can be contained in the positive electrode layer  110  and the negative electrode layer  120 , for example. Here, the positive electrode current collector layer and the negative electrode current collector layer are not essential components for the solid-state battery. 
     &lt;End Surface Electrode&gt; 
     The solid-state battery  1  is provided with an end surface electrode serving as the positive electrode  1 P and an end surface electrode serving as the negative electrode  1 N. These end surface electrodes preferably contain a material with high conductivity. Not especially limited, a specific material of the end surface electrode can be at least one selected from the group consisting of silver, gold, platinum, aluminum, copper, tin, and nickel. 
       FIG. 3  is a plan view illustrating a configuration of the power receiving coil  31 .  FIG. 3  illustrates only the power receiving coil  31  in particular. The power receiving coil  31  is wound multiple times to have a square spiral shape, and a coil opening CO is formed on the center. A coil having a spiral shape is also formed on the power transmission device, and this coil and the power receiving coil  31  are mutually coupled via a magnetic field. 
       FIG. 4  is a bottom view of the wireless rechargeable solid-state battery module  101 . In this example, eight terminals E 1  to E 8  are provided. The plane dimensions of the wireless rechargeable solid-state battery module  101  are X=10 mm and Y=11 mm, and a dimension of each of the terminals E 1  to E 8  is 1.8 mm×1.2 mm. 
     A name, a function, and a role of each terminal are shown below. 
     E 1 : VBAT+ battery voltage output terminal (2.0 V to 4.35 V) 
     E 2 : CSO charging state monitoring terminal 
     E 3 : VOUT positive electrode terminal (1.8 V or 3.0 V or 3.3 V) 
     E 4 : CE regulator Enable input terminal 
     E 5 : GND negative electrode terminal 
     E 6 : ISET charging current control input terminal 
     E 7 : THIN temperature monitoring NTC thermistor input terminal 
     E 8 : VIN voltage input terminal 
     Here, the battery voltage output terminal E 1  is a positive electrode output terminal of the solid-state battery  1 . The charging state monitoring terminal E 2  outputs a signal indicating a charging state of the solid-state battery  1 . The positive electrode terminal E 3  is an output terminal of an output voltage stabilization circuit. The regulator Enable input terminal E 4  is a switching signal terminal for enabling/disabling an operation of the output voltage stabilization circuit. The negative electrode terminal E 5  is a terminal of a ground potential. The charging current control input terminal E 6  is an input terminal for controlling charging current. The temperature monitoring NTC thermistor input terminal E 7  is a terminal that is used for connecting a negative characteristics (NTC) thermistor so as to detect an overheated state and perform corresponding processing. The voltage input terminal E 8  is a terminal that is used for inputting, for example, 5 V as a power supply voltage from the outside when wireless charging is not performed, and the voltage input terminal E 8  corresponds to a “voltage input terminal” according to the present disclosure. 
     Here, the terminals E 4 , E 6 , and E 7  can be configured to be unexposed to the outside. 
       FIG. 5  is a circuit diagram of the wireless rechargeable solid-state battery module  101 . This wireless rechargeable solid-state battery module  101  includes a wireless charging circuit  50 . The wireless charging circuit  50  includes the power receiving coil  31 , the rectifier circuit  52 , the DC-DC converter  54 , and a charge control circuit  55 . The power receiving coil  31  receives a power transmission magnetic field. The rectifier circuit  52  rectifies induced current of the power receiving coil  31 . The DC-DC converter  54  converts an output voltage of the rectifier circuit  52  so as to generate a charging voltage. The charge control circuit  55  inputs an output voltage of the DC-DC converter  54  so as to perform charging control of the solid-state battery  1 . Here, the DC-DC converter  54  corresponds to a “voltage conversion circuit” of the present disclosure. The power receiving coil  31  is expressed with an inductor  31 L and an equivalent resistance  31 R. A resonant capacitor  51  is connected to the power receiving coil  31 . The resonant capacitor  51  constitutes a resonant circuit LC 1  together with the power receiving coil  31 . A capacitor  531  is connected to an output of the rectifier circuit  52 . A capacitor  532  is connected to an output of the DC-DC converter  54 . Further, a protection circuit  56  is provided between the charge control circuit  55  and the solid-state battery  1 . A voltage regulator  57  is further provided between a connection point of the charge control circuit  55  and the protection circuit  56  and the positive electrode terminal E 3  and between the connection point and the negative electrode terminal E 5 . The voltage regulator  57  is, for example, a low dropout regulator (LDO) and is a linear regulator composed of a MOS-FET and an operational amplifier. The voltage regulator  57  stabilizes a voltage of the solid-state battery  1  and outputs the stabilized voltage to the positive electrode terminal E 3  and the negative electrode terminal E 5 . Here, the voltage regulator  57  corresponds to an “output voltage stabilization circuit” of the present disclosure. 
     The power receiving coil  31  and the rectifier circuit  52  are configured on the second circuit board  30  illustrated in  FIG. 1 . Other circuits are configured on the first circuit board  20 . 
     The resonant circuit LC 1  resonates in a frequency band of a magnetic field received from the power transmission device, such as frequency bands of 6.78 MHz and 13.56 MHz. These frequency bands are industrial scientific and medical (ISM) bands, and are favorable in a design with electromagnetic compatibility (EMC). The power receiving coil  31  outputs received power to the rectifier circuit  52 . The rectifier circuit  52  rectifies the received AC voltage to direct current. The capacitor  531  smooths an output voltage of the rectifier circuit  52  and outputs the voltage to the DC-DC converter  54 . The DC-DC converter  54  converts the voltage and outputs the converted voltage to the charge control circuit  55 . The capacitor  532  smooths the output voltage of the DC-DC converter  54 . The charge control circuit  55  charges the solid-state battery  1  with the received DC voltage that is obtained through the rectification from alternate current and through the voltage conversion. The voltage regulator  57  converts an output voltage of the solid-state battery  1  and outputs the converted voltage to the positive electrode terminal E 3  and the negative electrode terminal E 5 . 
     The protection circuit  56  performs overcurrent protection in charging/discharging of the solid-state battery  1  and performs protection for overvoltage input to the solid-state battery  1 . Further, the protection circuit  56  performs overheat protection depending on a resistance value of an NTC thermistor connected to the terminal E 7 . For example, when charging/discharging current to the solid-state battery  1  exceeds a specified value, the protection circuit  56  limits the current. Also, when a voltage of the solid-state battery  1  exceeds a predetermined value, the protection circuit  56  limits the charging current. Further, when the temperature or an ambient temperature of the solid-state battery  1  is out of a range of a predetermined value, the protection circuit  56  suppresses the charging or discharging. 
     In the example illustrated in  FIG. 5 , the voltage input terminal E 8  for inputting a voltage is connected to an input unit of the DC-DC converter  54 . In a state in which power reception is not performed with the power receiving coil  31 , the wireless rechargeable solid-state battery module  101  is operated by inputting a certain value or larger voltage (for example, 5 V) from the voltage input terminal E 8 . The voltage input terminal E 8  may be connected to the input unit of the rectifier circuit  52 . 
     The battery voltage output terminal E 1  is connected to the positive electrode of the solid-state battery  1  via the protection circuit  56 . The voltage of the solid-state battery  1  can be detected via the battery voltage output terminal E 1 . 
     The charge control circuit  55  includes a monitor signal output unit  55 M that outputs a signal which indicates a charging control state with respect to the solid-state battery  1 . The charging state monitoring terminal E 2  is connected to the monitor signal output unit  55 M. The charging control state of the solid-state battery  1  can be detected via the charging state monitoring terminal E 2 . 
       FIG. 6  is a perspective view illustrating an example of a state in which the wireless rechargeable solid-state battery module  101  of the present embodiment is mounted on the mounting board  80  and a positional relation with respect to a power transmission coil  900  of a power transmission device. The mounting board  80  on which the wireless rechargeable solid-state battery module  101  is mounted is housed in a casing of an electronic device, in practice. In a similar manner, the power transmission coil  900  is housed in a casing of the power transmission device. The coil opening of the power receiving coil (the power receiving coil  31  illustrated in  FIGS. 1 and 3 ) of the wireless rechargeable solid-state battery module  101  and a coil opening of the power transmission coil  900  are overlapped with each other in plan view. The power receiving coil  31  and the power transmission coil  900  are mutually coupled via a magnetic field in a state in which the power receiving coil  31  and the power transmission coil  900  are brought mutually closer within a prescribed distance, and power transmission/reception is performed via the magnetic field. In a similar manner, the illustration is omitted, but the power receiving coil  31  and the power transmission coil  900  can be exchanged for respective electrodes and mutually coupled via an electric field in a state in which the electrodes are brought mutually closer within a prescribed distance. 
       FIG. 7  is a perspective view illustrating another example of a state in which the wireless rechargeable solid-state battery module  101  of the present embodiment is mounted on the mounting board  80  and a positional relation with respect to a power transmission device  201 A. In this example, the power transmission device  201 A has an opening OP and a power transmission coil is formed in a manner to be wound around the opening OP. When the opening OP of the power transmission device  201 A is put over the wireless rechargeable solid-state battery module  101 , the coil opening of the power receiving coil and the coil opening of the power transmission coil are mutually overlapped in plan view. Power transmission/reception is performed via the magnetic field. In a similar manner, the illustration is omitted, but the power receiving coil and the power transmission coil can be exchanged for respective electrodes and power transmission/reception can be performed via an electric field. 
       FIG. 8  is a perspective view illustrating a state in which a power transmission device  201 B transmits power to a plurality of wireless rechargeable solid-state battery modules  101 A,  101 B, and  101 C. In this example, the power transmission device  201 B has a concave portion RE and a power transmission coil is formed in a manner to be wound around the concave portion RE. When the plurality of wireless rechargeable solid-state battery modules  101 , each of which is a single body, are put in the concave portion RE of the power transmission device  201 B, the coil opening of the power receiving coil in each of the wireless rechargeable solid-state battery modules and the coil opening of the power transmission coil are mutually overlapped in plan view. Power transmission/reception is performed via the magnetic field. In a similar manner, the illustration is omitted, but the power receiving coil and the power transmission coil can be exchanged for respective electrodes and power transmission/reception can be performed via an electric field. 
       FIG. 9  is a sectional view of another wireless rechargeable solid-state battery module  101 M according to the first embodiment. The wireless rechargeable solid-state battery module  101 M includes the solid-state battery  1 , the internal structures  11  and  12 , the barrier layers  14 , the buffer layer  15 , the mold resin portion  13 , the positive electrode terminal E 3 , and the negative electrode terminal E 5 . The mold resin portion  13  is provided on the upper portion from the internal structure  12 . 
     The electronic components  33   a  and  33   b  and the like such as a DC-DC converter IC and a capacitor are mounted on the outer surface (the opposite surface to the surface facing the solid-state battery  1 ) of the second circuit board  30 . 
     Other configurations are the same as those of the wireless rechargeable solid-state battery module  101  illustrated in  FIG. 1 . In the wireless rechargeable solid-state battery module  101 M illustrated in  FIG. 9 , the mold resin portion  13  is provided on the outer surface of the second circuit board  30  constituting the internal structure  12 , being able to mount electronic components on the outer surface of the second circuit board  30 . Thus, both surfaces of the second circuit board  30  can be more efficiently utilized. 
     Features of the wireless rechargeable solid-state battery modules  101  and  101 M described above will be listed as follows. 
     (1) A portion constituting a circuit (peripheral circuit) connected to the solid-state battery  1  is overlapped with the solid-state battery  1  in plan view, being able to provide a wireless rechargeable solid-state battery module that has substantially the same area as that of the solid-state battery  1  but is provided with the peripheral circuit. 
     (2) The incorporation of a peripheral circuit corresponding to characteristics of the solid-state battery  1  eliminates a necessity of designing based on characteristics of individual solid-state batteries on the user side, improving convenience. 
     (3) The second circuit board  30  is a flexible resin board having water resistance. Accordingly, the flexible resin board releases stress caused by expansion and contraction of the solid-state battery  1  while maintaining the water resistance, enhancing reliability of a charging/discharging cycle. 
     (4) The positive electrode terminal and the negative electrode terminal are arranged on a lower surface, having a large area, of a package having a rectangular parallelepiped shape, enabling surface mounting on a mounting board by a reflow soldering method. 
     (5) Wireless power transmission is performed, eliminating a need for a charging terminal and being able to simplify designing on water resistance of an electronic device on which the wireless rechargeable solid-state battery module is mounted. 
     Second Embodiment 
     A second embodiment will describe a wireless rechargeable solid-state battery module having a different circuit configuration from that in the example described in the first embodiment. 
       FIG. 10  is a circuit diagram of a wireless rechargeable solid-state battery module  102  according to the second embodiment. The wireless rechargeable solid-state battery module  102  includes the power receiving coil  31 , the rectifier circuit  52 , a voltage regulator  53 , the charge control circuit  55 , and the solid-state battery  1 . 
     The voltage regulator  53  is, for example, a low dropout regulator (LDO) and is a linear regulator composed of a MOS-FET and an operational amplifier. The voltage regulator  53  stabilizes an output voltage of the rectifier circuit  52 . The circuit configuration other than the voltage regulator  53  is the same as that in the example illustrated in  FIG. 5 . However, the example illustrated in  FIG. 10  does not include the voltage regulator  57 . 
     Thus, a rectified voltage may be stabilized with a linear regulator. This configuration achieves voltage regulation in a lower range of voltage induced by the power receiving coil  31 . 
     Third Embodiment 
     A third embodiment will describe a wireless rechargeable solid-state battery module having a different circuit configuration from that in the example described in the first embodiment. A circuit configuration of a power transmission device will be also described. 
       FIG. 11  is a circuit diagram of a wireless rechargeable solid-state battery module  103  according to the third embodiment. This wireless rechargeable solid-state battery module  103  includes the power receiving coil  31 , the rectifier circuit  52 , the DC-DC converter  54 , the charge control circuit  55 , the solid-state battery  1 , and the protection circuit  56 . 
     In the wireless rechargeable solid-state battery module  103 , the voltage regulator  57  is not provided and the positive electrode terminal E 3  and the negative electrode terminal E 5  are connected to the output unit of the solid-state battery  1 . Other configurations are the same as those of the example illustrated in  FIG. 5 . However,  FIG. 11  shows the rectifier circuit  52  with a diode bridge circuit. 
     A power transmission device  90  includes a power transmission control circuit  91 , the power transmission coil  900 , and a resonant capacitor  92 . The power transmission coil  900  is expressed with an inductor  900 L and an equivalent resistance  900 R. The power transmission coil  900  and the resonant capacitor  92  constitute a resonant circuit that resonates in a power transmission frequency band. The resonant circuit resonates in frequency bands of 6.78 MHz and 13.56 MHz, for example. These frequency bands are industrial scientific and medical (ISM) bands, and are favorable in a design with electromagnetic compatibility (EMC). The resonance circuit on the power transmission device side and the resonant circuit composed of the power receiving coil  31  and the resonant capacitor  51  on the wireless rechargeable solid-state battery module side are mutually coupled to produce magnetic field resonance. 
     The power transmission control circuit  91  of the power transmission device  90  interrupts direct current traveling to the power transmission coil  900  so as to generate an alternating magnetic field from the power transmission coil  900 . Thus, power is transmitted from the power transmission device  90  to the wireless rechargeable solid-state battery module  103  with the use of a DC resonant technique. 
     The wireless rechargeable solid-state battery module  103  outputs 3.7 V, for example, as a discharging voltage of the solid-state battery  1 . 
     According to the present embodiment, power is transmitted from the power transmission device to the wireless rechargeable solid-state battery module by using the DC resonant technique and therefore, highly efficient charging can be achieved. This configuration enhances flexibility in the positional relation between the power transmission device and the wireless rechargeable solid-state battery module. 
     Fourth Embodiment 
     A fourth embodiment will describe a wireless rechargeable solid-state battery module that transmits a communication signal to a power transmission device. 
       FIG. 12  is a circuit diagram of a wireless rechargeable solid-state battery module  104  according to the fourth embodiment. This wireless rechargeable solid-state battery module  104  includes the power receiving coil  31 , the rectifier circuit  52 , the DC-DC converter  54 , the charge control circuit  55 , the solid-state battery  1 , the protection circuit  56 , a transmission control circuit  70 , and a transmission circuit  59 . 
     The transmission circuit  59  transmits a communication signal in response to change of power consumption of a circuit connected with the power receiving coil  31 . That is, binary amplitude-shift keying (ASK) is performed in a manner such that a load on the power receiving side is changed by backscatter modulation similar to a passive RFID tag. Alternatively, the transmission circuit  59  changes a resonance condition of the resonant circuit composed of the power receiving coil  31  and the resonant capacitor  51  so as to transmit a signal through this change. For example, the resonant capacitor  51  and the transmission circuit  59  change an equivalent resonant capacitance so as to change a resonant frequency of the resonant circuit. This changes an impedance of the resonant circuit based on the power transmission device with respect to the power receiving side and the power transmission device accordingly receives a communication signal. The transmission circuit  59  corresponds to a “signal transmission circuit” according to the present disclosure. 
     The transmission control circuit  70  inputs an output voltage of the rectifier circuit  52 , a voltage of the solid-state battery  1 , and the like and produces transmission data based on these values. The transmission data include difference of a received power amount with respect to a required amount, a power transmission stop request, power being received, and a charging rate to the solid-state battery  1 , for example. 
     Fifth Embodiment 
     A fifth embodiment will describe a wireless rechargeable solid-state battery module including a power reception protection circuit that stops power reception when a received voltage exceeds a prescribed voltage range. 
       FIG. 13  is a circuit diagram of a wireless rechargeable solid-state battery module  105  and the like.  FIG. 13  also illustrates a circuit of the power transmission device  90 . 
     This wireless rechargeable solid-state battery module  105  includes the solid-state battery  1  and the wireless charging circuit  50  that is connected to the solid-state battery  1 . The wireless charging circuit  50  includes the power receiving coil  31 , a power reception protection circuit  58 , the DC-DC converter  54 , the charge control circuit  55 , the protection circuit  56 , and the voltage regulator  57 . The power receiving coil  31  receives a power transmission magnetic field or a power transmission electromagnetic field. The DC-DC converter  54  converts an output voltage of a rectifying and smoothing circuit included in the power reception protection circuit  58  so as to generate a charging voltage. The charge control circuit  55  inputs an output voltage of the DC-DC converter  54  so as to perform charging control of the solid-state battery  1 . The protection circuit  56  protects the solid-state battery  1 . The voltage regulator  57  converts current of the solid-state battery  1  into an output voltage for a general-purpose battery. The power reception protection circuit  58  rectifies induced current of the power receiving coil  31 , and stops power reception of the DC-DC converter  54  when a received voltage exceeds a prescribed voltage range. 
     The power receiving coil  31  is expressed with the inductor  31 L and the equivalent resistance  31 R. The resonant capacitor  51  is connected to the power receiving coil  31 . The resonant capacitor  51  constitutes a resonant circuit together with the power receiving coil  31 . The rectifier circuit  52  includes a smoothing capacitor C 3 . The capacitor  532  is connected to the output of the DC-DC converter  54 . The voltage regulator  57  is, for example, a low dropout regulator (LDO) and is a linear regulator composed of a MOS-FET and an operational amplifier. The voltage regulator  57  stabilizes a voltage of the solid-state battery  1  and outputs the stabilized voltage to the positive electrode terminal E 3  and the negative electrode terminal E 5 . 
     The power transmission device  90  includes the power transmission control circuit  91 , the power transmission coil  900 , and the resonant capacitor  92 . The power transmission coil  900  is expressed with the inductor  900 L and the equivalent resistance  900 R. The power transmission coil  900  and the resonant capacitor  92  constitute a resonant circuit that resonates in a power transmission frequency band. The resonant circuit resonates in frequency bands of 6.78 MHz and 13.56 MHz, for example. These frequency bands are industrial scientific and medical (ISM) bands, and are favorable in a design with electromagnetic compatibility (EMC). The resonance circuit on the power transmission device side and the resonant circuit composed of the power receiving coil  31  and the resonant capacitor  51  on the wireless rechargeable solid-state battery module  105  side are mutually coupled to produce magnetic field resonance. 
     The resonant circuit composed of the power receiving coil  31  and the resonant capacitor  51  resonates in a frequency band of an electromagnetic field or a magnetic field received from the power transmission device  90 , such as frequency bands of 6.78 MHz and 13.56 MHz. The power receiving coil  31  outputs received power to the power reception protection circuit  58 . The power reception protection circuit  58  rectifies a received AC voltage into direct current, and stops power reception of the DC-DC converter  54  when a received voltage exceeds a prescribed voltage range. The DC-DC converter  54  converts a voltage and outputs the converted voltage to the charge control circuit  55 . The capacitor  532  smooths the output voltage of the DC-DC converter  54 . The charge control circuit  55  charges the solid-state battery  1  with the received DC voltage that is obtained through the rectification from alternate current and through the voltage conversion. The voltage regulator  57  converts an output voltage of the solid-state battery  1  and outputs the converted voltage to the positive electrode terminal E 3  and the negative electrode terminal E 5 . 
     The protection circuit  56  performs overcurrent protection in charging/discharging of the solid-state battery  1  and performs protection for overvoltage input to the solid-state battery  1 . Further, the protection circuit  56  performs overheat protection depending on a resistance value of a NTC thermistor. For example, when charging/discharging current to the solid-state battery  1  exceeds a specified value, the protection circuit  56  limits the current. Also, when a voltage of the solid-state battery  1  exceeds a predetermined value, the protection circuit  56  limits the charging current. Further, when the temperature or an ambient temperature of the solid-state battery  1  is out of a range of a predetermined value, the protection circuit  56  suppresses the charging or discharging. 
       FIGS. 14A, 14B, 14C, and 14D  are circuit diagrams illustrating specific examples of the power reception protection circuit  58 . 
     In the example illustrated in  FIG. 14A , a rectifying and smoothing circuit is composed of a diode D 1  and a capacitor C 3 . When a received voltage exceeds Zener voltages of Zener diodes ZD 1  and ZD 2 , both ends of a connection circuit of the Zener diodes ZD 1  and ZD 2  are brought into conduction and the received voltage is limited to the Zener voltage. 
     In the example illustrated in  FIG. 14B , a rectifying and smoothing circuit is composed of a diode D 1  and a capacitor C 3 . When a divided voltage of resistances R 1  and R 2  exceeds a Zener voltage of a Zener diode ZD, the Zener diode ZD is brought into conduction and a received voltage is limited by a series circuit composed of the Zener diode and a resistance. 
     In the example illustrated in  FIG. 14C , a rectifying and smoothing circuit is composed of a diode D 1  and a capacitor C 3 . When a rectified and smoothed voltage exceeds a Zener voltage of a Zener diode ZD, a FET Q is brought into conduction and a received voltage is limited by a series circuit composed of the FET Q and resistances. 
     In the example illustrated in  FIG. 14D , a rectifying and smoothing circuit is composed of a diode D 1  and a capacitor C 3 . When a rectified and smoothed voltage exceeds a Zener voltage of a Zener diode ZD, the Zener diode ZD is brought into conduction and a received voltage is limited to the Zener voltage. 
     Thus, when a received voltage exceeds a prescribed voltage range, the power reception protection circuit  58  protects the DC-DC converter  54 . 
       FIG. 15  is another circuit diagram of the wireless rechargeable solid-state battery module  105  and the like according to the fifth embodiment. The wireless rechargeable solid-state battery module  105  includes the solid-state battery  1  and the wireless charging circuit  50  that is connected to the solid-state battery  1 . The wireless charging circuit  50  includes the power receiving coil  31 , the rectifier circuit  52 , a cutoff circuit  58 C, a resistance voltage dividing circuit  58 R, a received voltage detection circuit  58 D, the DC-DC converter  54 , and the charge control circuit  55 . The power receiving coil  31  receives a power transmission magnetic field. The rectifier circuit  52  rectifies induced current of the power receiving coil  31 . The cutoff circuit  58 C stops power reception of the rectifier circuit  52  when a received voltage exceeds a prescribed voltage range. The DC-DC converter  54  converts an output voltage of the rectifier circuit  52  so as to generate a charging voltage. The charge control circuit  55  inputs an output voltage of the DC-DC converter  54  so as to perform charging control of the solid-state battery  1 . The wireless rechargeable solid-state battery module  105  further includes the protection circuit  56  and the voltage regulator  57 . The protection circuit  56  protects the solid-state battery  1 . The voltage regulator  57  converts current of the solid-state battery  1  into an output voltage for a general-purpose battery. The power reception protection circuit  58  is composed of the cutoff circuit  58 C, the received voltage detection circuit  58 D, and the resistance voltage dividing circuit  58 R. 
     When the received voltage detection circuit  58 D detects that an output voltage of the resistance voltage dividing circuit  58 R exceeds a prescribed value, the received voltage detection circuit  58 D outputs a detection signal to the cutoff circuit  58 C. When the cutoff circuit  58 C receives the detection signal from the received voltage detection circuit  58 D, the cutoff circuit  58 C stops power reception of the rectifier circuit  52 . 
       FIGS. 16A and 16B  are diagrams for explaining an operation of the cutoff circuit  58 C in normal power-reception time. In the normal power-reception time, a FET Q 2  of the cutoff circuit  58 C is in an off state. 
     When the first end of the power receiving coil  31  on the capacitor  51  side becomes positive as illustrated in  FIG. 16A , current flows in a path along the capacitor  51 , the diode D 1 , and the capacitor C 3  from the power receiving coil  31 . In this case, a voltage obtained by adding a voltage, charged to the capacitor  51 , to a voltage induced by the power receiving coil  31  is charged to the capacitor C 3 . That is, this voltage is supplied to the rectifier circuit  52 . 
     When the second end of the power receiving coil  31  is positive as illustrated in  FIG. 16B , current flows from the power receiving coil  31  through a body diode of the FET Q 2  to the capacitor  51 . Thus, the capacitor  51  is charged. 
     In the normal power-reception time, the state illustrated in  FIG. 16A  and the state illustrated in  FIG. 16B  are alternately repeated, outputting a received voltage to the rectifier circuit  52 . 
       FIGS. 17A and 17B  are diagrams for explaining an operation of the cutoff circuit  58 C in a state in which a received voltage exceeds a specified value. The FET Q 2  shifts to an on state in response to the detection signal outputted from the received voltage detection circuit  58 D illustrated in  FIG. 15 . 
     When a voltage is induced by the power receiving coil  31  and the first end of the power receiving coil  31  becomes positive as illustrated in  FIG. 17A , current flows in a path along the capacitor  51  and the FET Q 2  from the power receiving coil  31 . When the second end of the power receiving coil  31  is positive as illustrated in  FIG. 17B , current flows from the power receiving coil  31  through the body diode of the FET Q 2  to the capacitor  51 . In the state in which the received voltage exceeds the specified value, the state illustrated in  FIG. 17A  and the state illustrated in  FIG. 17B  are alternately repeated. That is, a received voltage is not outputted to the rectifier circuit  52 . 
     Accordingly, even if the power receiving coil  31  receives a magnetic field that is larger than a specified value, power can be cut off by cutting off power reception of the rectifier circuit  52 , being able to suppress an influence of heat generation and the like caused by high power reception in the rectifier circuit  52  and circuits on the following stages. 
       FIGS. 18A and 18B  are diagrams illustrating configuration examples of the received voltage detection circuit  58 D illustrated in  FIG. 15 . 
     In the example illustrated in  FIG. 18A , the received voltage detection circuit  58 D includes comparators  25 A and  25 B and a control unit  25 C. The comparator  25 A compares a received voltage Va with a threshold voltage Va 1 . The comparator  25 A outputs an H level signal (H) when Va&gt;Va 1  is established, and the comparator  25 A outputs an L level signal (L) when Va≤Va 1  is established. The comparator  25 B compares the received voltage Va with a threshold voltage Va 2 . The comparator  25 B outputs the H level signal (H) when Va&gt;Va 2  is established, and the comparator  25 B outputs the L level signal (L) when Va≤Va 2  is established. 
     The control unit  25 C outputs a gate signal to the FET Q 2  based on output signals of the comparators  25 A and  25 B. In detail, when both of the output signals of the comparators  25 A and  25 B are L, namely, when Va&lt;Va 1  is established, the control unit  25 C turns off the FET Q 2 . When the output signal of the comparator  25 A is H and the output signal of the comparator  25 B is L, namely, when Va 1 &lt;Va&lt;Va 2  is established, the control unit  25 C outputs a pulse signal to a gate of the FET Q 2  so as to turn on and off the FET Q 2 . When both of the output signals of the comparators  25 A and  25 B are H, namely, when Va 2 &lt;Va is established, the control unit  25 C turns on the FET Q 2 . 
     In the example illustrated in  FIG. 18B , the cutoff circuit  58 C includes a series circuit for driving the FET Q 2 . The series circuit is composed of a resistance R 1  and a FET Q 21 . A connection point between the resistance R 1  and the FET Q 21  is connected to the gate of the FET Q 2 . 
     The cutoff circuit  58 C illustrated in  FIG. 18B  includes the resistance R 2  and the FET Q 21 . The received voltage detection circuit  58 D includes a series circuit composed of the resistance R 2  and a Zener diode Dz 1 . A connection point A between the resistance R 2  and the Zener diode Dz 1  is connected to the gate of the FET Q 21 . 
     When the received voltage Va is lower than the Zener voltage of the Zener diode Dz 1  in this configuration, a potential of the connection point A is H and the FET Q 21  is turned on. Accordingly, a potential of a connection point between the resistance R 1  and the FET Q 21  is L and the FET Q 2  is turned off. When the received voltage Va rises and exceeds the Zener voltage, the potential of the connection point A becomes L and the FET Q 21  is turned off and the FET Q 2  is turned on. The Zener voltage is set so that the FET Q 2  is turned off when the received voltage Va is equal to or lower than the threshold voltage Va 1 . 
     When the received voltage Va exceeds the Zener voltage and the FET Q 2  is turned on, a power reception cutoff state starts. Accordingly, the capacitor C 3  discharges and the received voltage Va is lowered. When the received voltage Va becomes to be lower than the Zener voltage, the potential of the connection point A becomes H and the FET Q 2  is turned off again. Then, when the received voltage Va exceeds the Zener voltage again, the FET Q 2  is turned on. This process is repeated and excessive received voltage is suppressed. 
     When the received voltage Va is higher than a specified value (when equal to or higher than the threshold voltage Va 2 ), the FET Q 2  is turned on and the power reception cutoff state starts. The cutoff circuit  58 C maintains the cutoff state and power reception is stopped until the received voltage Va becomes to be lower than the Zener voltage. 
       FIG. 19  is a circuit diagram illustrating a specific example of the protection circuit  56 . The protection circuit  56  is composed of a protection IC and FETs Q 61  and Q 62 . The protection IC detects both end voltages of the solid-state battery  1 . When an applied voltage of the solid-state battery  1  exceeds a prescribed voltage, the protection IC controls gate voltages of the FETs Q 61  and Q 62  and cuts off a charging current path to the solid-state battery  1 . 
     Sixth Embodiment 
     A sixth embodiment will describe an example of a circuit that cuts off power reception by controlling a rectifying element. 
       FIG. 20  and  FIG. 21  are diagrams illustrating configurations of a cutoff circuit of a wireless rechargeable solid-state battery module according to the sixth embodiment. In  FIG. 20 , the FET Q 2  and a FET Q 31  constitute a synchronous rectifier circuit. The received voltage detection circuit  58 D controls the FETs Q 2  and Q 31  so as to control a synchronous rectification operation. That is, in conducting power reception cutoff, the FET Q 2  is shifted to the on state and the FET Q 31  is shifted to the off state. 
     In  FIG. 21 , a FET Q 32  and a diode D 12  constitute a rectifier circuit. The received voltage detection circuit  58 D controls the FET Q 32  so as to control a rectification operation. That is, in conducting power reception cutoff, the FET Q 32  is shifted to the off state. 
     Seventh Embodiment 
     A seventh embodiment will describe a configuration example of a power reception protection circuit provided with a bridge rectifier circuit. 
       FIG. 22  and  FIG. 23  are circuit diagrams partially illustrating a wireless rechargeable solid-state battery module and a power transmission device according to the seventh embodiment. 
     Referring to  FIG. 22 , the power transmission device includes a power transmission-side resonant circuit  111  and a power transmission circuit  122 A. The power transmission circuit  122 A is configured in a manner such that a series circuit composed of FETs Q 11  and Q 12  and a series circuit composed of FETs Q 13  and Q 14  are connected in parallel. A DC voltage from a DC power supply is converted into an AC voltage by alternately turning on and off the FETs Q 11  and Q 14  and the FETs Q 12  and Q 13  and the AC voltage is supplied to the power transmission-side resonant circuit  111 . 
     In  FIG. 22 , a rectifier circuit is configured in a manner such that a series circuit composed of a FET Q 51  and a diode D 31  and a series circuit composed of a FET Q 52  and a diode D 32  are connected in parallel. The received voltage detection circuit  58 D ( FIG. 15 ) performs switching control with respect to the FETs Q 51  and Q 52 . 
     Referring to  FIG. 23 , a diode bridge rectifier circuit composed of diodes D 31 , D 32 , D 33 , and D 34  and the FETs Q 51  and Q 52  are provided. This configuration is different from the example illustrated in  FIG. 22  in the directions of drains and sources of the FETs Q 51  and Q 52 . 
     In either of the examples illustrated in  FIGS. 21 and 22 , the FETs Q 51  and Q 52  are shifted to the off state and rectification by the diodes D 31 , D 32 , D 33 , and D 34  is blocked in conducting power reception cutoff. 
     Finally, the description of the embodiments described above is exemplary in all aspects and not restrictive. Those skilled in the art can appropriately make modifications and changes. The scope of the present disclosure is indicated by the claims rather than the embodiments described above. Further, the scope of the present disclosure includes changes from the embodiments within the scope equivalent to the scope of the claims.