Secondary battery and electric equipment

Abstract

The utility model discloses a secondary battery and electric equipment, and belongs to the technical field of batteries, the secondary battery comprises a single battery and a battery protection board, the battery protection board comprises a first switch circuit and a first protection circuit, the first switch circuit is connected with the single battery in series, the first switch circuit comprises a first field effect transistor, and the first field effect transistor is connected with the first protection circuit. The first protection circuit is connected with a back gold layer of the first field effect transistor and is also connected with a grid electrode of the first field effect transistor; according to the invention, the back gold layer of the field-effect transistor is used for replacing a precision resistor, and the back gold layer of the field-effect transistor is connected with the protection circuit, so that the design of the precision resistor in the battery protection board can be reduced, the design area of an electrical element can be reduced, and the area of the battery protection board can be reduced, thereby adjusting the size of the battery.

Description

Technical Field

[0001] This application belongs to the technical field of batteries, and particularly relates to a secondary battery and an electrical device. Background Art

[0002] A secondary battery includes a single cell and a battery protection board. The battery protection board is connected to the single cell to protect the single cell during charging and discharging. However, with the increasing design requirements and the update and iteration of devices, more and more electrical components are integrated on the battery protection board. To ensure functional requirements, the length of the battery protection board has to be increased, which inevitably affects the size of the battery. Summary of the Utility Model

[0003] Purpose of the Utility Model: This application develops a secondary battery and an electrical device, aiming to solve the technical problem in the prior art that the design size is large due to the large number of electrical components integrated on the battery protection board.

[0004] Technical Solution: In a first aspect, an embodiment of this application provides a secondary battery, including:

[0005] A single cell;

[0006] A battery protection board, where the battery protection board includes:

[0007] A first switch circuit, the first switch circuit is connected in series with the single cell; the first switch circuit includes a first field-effect transistor;

[0008] A first protection circuit, the first protection circuit is respectively connected to the back metal layer and the gate of the first field-effect transistor.

[0009] In some embodiments, the first protection circuit is connected in parallel with the single cell.

[0010] In some embodiments, the first switch circuit further includes:

[0011] A second field-effect transistor, the gate of the second field-effect transistor is connected to the first protection circuit, and the drain of the second field-effect transistor is connected to the drain of the first field-effect transistor;

[0012] A first diode, the first diode is connected in parallel with the source and drain of the first field-effect transistor, and the flow direction of the first diode is from the source to the drain of the first field-effect transistor;

[0013] A second diode, the second diode is connected in parallel with the source and drain of the second field-effect transistor, and the flow direction of the second diode is from the source to the drain of the second field-effect transistor.

[0014] In some embodiments, the battery protection board further includes:

[0015] A second switching circuit, the second switching circuit being connected in series with the first switching circuit;

[0016] A second protection circuit, the second protection circuit, the first protection circuit and the single cell being connected in parallel; the second protection circuit is connected to the second switching circuit for adjusting the on / off of the second switching circuit.

[0017] In some embodiments, the first switching circuit and the second switching circuit are connected in series with the same electrode of the single cell.

[0018] In some embodiments, the second switching circuit includes:

[0019] A third field-effect transistor, the gate of the third field-effect transistor being connected to the second protection circuit;

[0020] A fourth field-effect transistor, the gate of the fourth field-effect transistor being connected to the second protection circuit, the drain of the fourth field-effect transistor being connected to the drain of the third field-effect transistor;

[0021] A third diode, the third diode being connected in parallel with the source and drain of the third field-effect transistor, the current flow direction of the third diode being from the source to the drain of the third field-effect transistor;

[0022] A fourth diode, the fourth diode being connected in parallel with the source and drain of the fourth field-effect transistor, the current flow direction of the fourth diode being from the source to the drain of the fourth field-effect transistor.

[0023] In some embodiments, both the first protection circuit and the second protection circuit are connected to the back gold layer of the first field-effect transistor, and / or both the first protection circuit and the second protection circuit are connected to the back gold layer of the second field-effect transistor;

[0024] Alternatively, both the first protection circuit and the second protection circuit are connected to the back gold layer of the third field-effect transistor, and / or both the first protection circuit and the second protection circuit are connected to the back gold layer of the fourth field-effect transistor.

[0025] In some embodiments, the battery protection board further includes an anti-counterfeiting function circuit, the anti-counterfeiting function circuit being connected in parallel with the single cell.

[0026] In some embodiments, the battery protection board further includes a temperature detection circuit, the temperature detection circuit being connected in parallel with the single cell.

[0027] In a second aspect, an embodiment of the present application further provides an electrical device, including the secondary battery according to any one of the first aspect.

[0028] Beneficial effects: Compared with the prior art, a secondary battery provided by an embodiment of the present application includes a single battery and a battery protection board. The battery protection board includes a first switch circuit and a first protection circuit. The first switch circuit is connected in series with the single battery. The first switch circuit includes a first field-effect transistor. The first protection circuit is connected to the back gold layer of the first field-effect transistor and is also connected to the gate of the first field-effect transistor. The present application uses the back gold layer of the field-effect transistor to replace the precision resistor, connects the back gold layer of the field-effect transistor to the protection circuit, and can reduce the design of the precision resistor in the battery protection board, so as to reduce the number of electrical components, reduce the design area of the electrical components, reduce the area of the battery protection board, and thus reduce the influence of the size of the battery protection board on the size of the battery. Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0030] Figure 1 The first circuit diagram of the secondary battery provided by the embodiment of the present application;

[0031] Figure 2 The second circuit diagram of the secondary battery provided by the embodiment of the present application;

[0032] Figure 3 The third circuit diagram of the secondary battery provided by the embodiment of the present application;

[0033] Figure 4 The fourth circuit diagram of the secondary battery provided by the embodiment of the present application;

[0034] Figure 5 The fifth circuit diagram of the secondary battery provided by the embodiment of the present application;

[0035] Figure 6 The sixth circuit diagram of the secondary battery provided by the embodiment of the present application;

[0036] Figure 7 The seventh circuit diagram of the secondary battery provided by the embodiment of the present application;

[0037] Figure 8 The specific circuit diagram of the first switch circuit in the secondary battery provided by the embodiment of the present application;

[0038] Figure 9 The specific circuit diagram when a field-effect transistor is selected for the second switch circuit in the secondary battery provided by the embodiment of the present application;

[0039] Figure 10It is a schematic structural diagram of a field effect transistor;

[0040] Reference numerals: 1, back gold layer; 2, silicon layer; 3, passivation layer; 4, insulating layer; 5, pad; 10, single cell; 20, battery protection board; 21, first switch circuit; 211, first field effect transistor; 212, second field effect transistor; 213, first diode; 214, second diode; 22, first protection circuit; 23, second switch circuit; 231, third field effect transistor; 232, fourth field effect transistor; 233, third diode; 234, fourth diode; 24, second protection circuit; 30, anti-counterfeiting function circuit; 40, temperature detection circuit; 50, output terminal. Specific embodiments

[0041] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts belong to the scope of protection of the present application.

[0042] The secondary battery includes a single cell and a battery protection board. The battery protection board is connected to the single cell to protect the single cell during charging and discharging. However, with the increase and update of equipment, more and more electrical components are integrated on the battery protection board. To ensure the functional requirements, it is necessary to increase the length of the battery protection board, which will inevitably affect the design size of the battery and make the battery design larger and larger.

[0043] Please refer to Figure 10 , the field effect transistor includes a back gold layer 1, a silicon layer 2, a passivation layer 3, an insulating layer 4 and a pad 5. After comparison, it is found that the resistance value of the precision resistor in the battery protection board is similar to the resistance value of the back gold layer 1 of the field effect transistor. The current in the circuit can be monitored by detecting the voltage of the back gold layer 1 to achieve the charging and discharging protection of the battery. In this way, on the premise of ensuring the charging and discharging protection function, the back gold layer 1 of the field effect transistor can be used to replace the precision resistor, so as to cancel the design of the precision resistor on the battery protection board and reduce the area of the battery protection board, so as to reduce the influence of the size of the battery protection board on the size of the battery.

[0044] Based on the above technical concept, an embodiment of the present application provides a secondary battery. Specifically, the secondary battery includes a single cell 10 and a battery protection board 20. The battery protection board 20 includes a first switch circuit 21 and a first protection circuit 22. The first switch circuit 21 is connected in series with the single cell 10. The first switch circuit 21 includes a first field effect transistor 211. The first protection circuit 22 is connected to the back gold layer 1 of the first field effect transistor 211 and is also connected to the gate of the first field effect transistor 211. In the present application, the back gold layer 1 of the field effect transistor is used to replace the precision resistor. By connecting the back gold layer 1 of the field effect transistor to the protection circuit, the design of the precision resistor in the battery protection board 20 can be reduced, the design area of the electrical components can be reduced, and the area of the battery protection board 20 can be reduced, so as to reduce the influence of the size of the battery protection board 20 on the size of the battery.

[0045] Please refer to Figures 1 to 9 ( Figure 1 showing the first protection circuit 22 and the first switch circuit 21, wherein the first switch circuit 21 is connected to the negative electrode of the single cell 10; Figure 2 showing the first protection circuit 22 and the first switch circuit 21, wherein the first switch circuit 21 is connected to the positive electrode of the single cell 10; Figure 3 showing the first protection circuit 22, the second protection circuit 24, the first switch circuit 21 and the second switch circuit 23, wherein the first switch circuit 21 and the second switch circuit 23 are connected to the negative electrode of the single cell 10, and the first protection circuit 22 and the second protection circuit 24 are connected to the back gold layer 1 of the first switch circuit 21; Figure 4 showing the first protection circuit 22, the second protection circuit 24, the first switch circuit 21 and the second switch circuit 23, wherein the first switch circuit 21 and the second switch circuit 23 are connected to the positive electrode of the single cell 10, and the first protection circuit 22 and the second protection circuit 24 are connected to the back gold layer 1 of the second switch circuit 23; Figure 5 showing the first protection circuit 22, the second protection circuit 24, the first switch circuit 21 and the second switch circuit 23, wherein the first switch circuit 21 and the second switch circuit 23 are connected to the positive electrode of the single cell 10, and the first protection circuit 22 and the second protection circuit 24 are connected to the back gold layer 1 of the first switch circuit 21; Figure 6 showing the first protection circuit 22, the second protection circuit 24, the first switch circuit 21 and the second switch circuit 23, wherein the first switch circuit 21 and the second switch circuit 23 are connected to the positive electrode of the single cell 10, and the first protection circuit 22 and the second protection circuit 24 are connected to the back gold layer 1 of the second switch circuit 23; Figure 7 showing Figure 3 some specific electronic components), and next, the secondary battery provided by the embodiment of the present application will be introduced in detail.

[0046] In some embodiments, please refer toFigures 1 to 7 The first protection circuit 22 is connected in parallel with the single cell 10 to detect the electrical signal data of the single cell 10. After the electrical signal data becomes abnormal, it controls the first switch circuit 21 to cut off the charge and discharge circuit of the single cell 10, so as to achieve the charge and discharge protection of the single cell 10. Specifically, the single cell 10 is the battery CELL, and the first protection circuit 22 includes a first battery management chip U1, a first resistor R1, a first capacitor C1, a third resistor R3, a second capacitor C2, and a sixth resistor R6. Among them, the first battery management chip U1 includes a VDD pin (Voltage Drain to Drain pin, power supply pin), a GND pin (Ground pin, ground pin), a VI pin (Voltage Input, voltage input pin), a DSG pin (Drain Source Gate pin, drain-source-gate pin, which is the control and connection pin of the field effect transistor or other power switch transistors in the battery management chip), a CHG pin (Charge pin, charge control related function or signal pin), and a VM pin (Voltage Monitor pin, voltage monitoring pin).

[0047] Specifically, please refer to Figure 7 The first resistor R1 and the first capacitor C1 are connected in parallel and then connected in series to the VDD pin to form an RC parallel circuit to attenuate the low-frequency signals in the electrical signals input from the battery CELL to the first battery management chip U1. Further, the first resistor R1 is connected in series between the battery CELL and the VDD pin, and the first capacitor C1 is connected in series to the VDD pin and then grounded.

[0048] Specifically, please refer to Figure 7 The third resistor R3 is connected in series as an overcurrent detection resistor between the VM pin and the input end of the first protection circuit 22.

[0049] Specifically, please refer to Figure 7 The VI pin is used to connect to the back gold layer 1 to obtain the voltage signal of the back gold layer 1. Further, the second capacitor C2 and the sixth resistor R6 are connected in parallel and then connected in series to the VI pin to attenuate the low-frequency signals in the electrical signals input from the back gold layer 1 to the first battery management chip U1. Further, the sixth resistor R6 is connected in series between the back gold layer 1 and the VI pin, and the second capacitor C2 is connected in series to the VI pin and then grounded.

[0050] Specifically, please refer to Figure 7 The gate of the first field effect transistor 211 is connected to the DSG pin to receive the protection signal output by the first resistor R1, and based on the protection signal, it controls the on and off of the first field effect transistor 211 to control the on and off of the charge and discharge circuit of the single cell 10, so as to achieve the purpose of charge and discharge protection.

[0051] In some embodiments, please refer to Figure 7 and Figure 8 , the first switch circuit 21 further includes a second field effect transistor 212, a first diode 213, and a second diode 214. Outside the battery CELL, along the current flow direction, the second field effect transistor 212 and the first field effect transistor 211 are connected in sequence. Along the current direction, the second diode 214 is connected in parallel with the second field effect transistor 212. Along the reverse current direction, the first diode 213 is connected in parallel with the first field effect transistor 211. Specifically, the drain of the second field effect transistor 212 is connected to the drain of the first field effect transistor 211; the first diode 213 is connected in parallel between the source and the drain of the first field effect transistor 211, and the flow direction of the first diode 213 is from the source to the drain of the first field effect transistor 211; the gate of the second field effect transistor 212 is connected to the CHG pin to obtain the protection signal of the first battery management chip U1, and based on the protection signal, control its own on and off to cooperate with the first field effect transistor 211 to complete the charge and discharge protection of the battery CELL; the second diode 214 is connected in parallel between the source and the drain of the second field effect transistor 212, and the flow direction of the second diode 214 is from the source to the drain of the second field effect transistor 212.

[0052] Specifically, please refer to Figure 7 and Figure 8 , the first field effect transistor 211, the second field effect transistor 212, the first diode 213, and the second diode 214 in the first switch circuit 21 are packaged together. The external pins after the first switch is packaged include pin 1, pin 2, pin 3, pin 4, pin 5, pin 6, pin 7, pin 8, pin 9, and pin 10; among them, pin 1 is grounded, and pin 2, pin 4, and pin 5 are connected in parallel and then connected in series to the source of the first field effect transistor 211. Pin 6, pin 7, pin 9, and pin 10 are connected in parallel and then connected in series to the source of the second field effect transistor 212. Pin 3 is connected in series between the source of the first field effect transistor 211 and the DSG pin. Pin 8 is connected in series between the gate of the second field effect transistor 212 and the CHG pin.

[0053] In some embodiments, please refer to Figure 7 , the secondary battery provided by the embodiment of the present application further includes a third capacitor C3. The third capacitor C3 is connected in series with the first protection circuit 22 to filter the current flowing through the first protection circuit 22. Specifically, one end of the third capacitor C3 is connected in series to pin 6, pin 7, pin 9, and pin 10, and the other end of the third capacitor C3 is connected in series to pin 2, pin 4, and pin 5.

[0054] In some embodiments, please refer to Figures 1 to 7 , the first switch circuit 21 can be connected in series to the positive electrode or the negative electrode of the battery CELL, which is actually selected according to engineering requirements and will not be elaborated here.

[0055] In some embodiments, please refer to Figures 3 to 7 , and Figure 9 , the battery protection board 20 of the secondary battery provided by the embodiments of the present application further includes a second switch circuit 23 and a second protection circuit 24; the second switch circuit 23 is connected in series with the first switch circuit 21 to cooperate with the first switch circuit 21 to jointly control the on and off of the battery CELL charge and discharge circuit, realizing double charge and discharge protection; the second protection circuit 24, the first protection circuit 22 and the single battery 10 are connected in parallel; the second protection circuit 24 is connected to the second switch circuit 23 to output a protection signal to the second switch circuit 23 to control the on and off of the second switch circuit 23.

[0056] Specifically, please refer to Figure 7 , the second protection circuit 24 includes a second battery management chip U2, a second resistor R2, a fourth capacitor C4, a fourth resistor R4, a fifth capacitor C5 and a seventh resistor R7. Among them, the second battery management chip U2 and the first battery management chip U1 use the same chip, and the design connection methods of the second battery management chip U2, the second resistor R2, the fourth capacitor C4, the fourth resistor R4, the fifth capacitor C5 and the seventh resistor R7 in the second protection circuit 24 are the same as those of the first protection circuit 22. For specific reference, please refer to the description of the first protection circuit 22, which will not be elaborated here.

[0057] In some embodiments, please refer to Figure 3 , Figure 5 and Figure 7 The VI pins of the first battery management chip U1 in the first protection circuit 22 and the VI pins of the second battery management chip U2 in the second protection circuit 24 are both connected to the back gold layer 1 in the first protection circuit 22 to uniformly detect the input of signals, ensure that the first protection circuit 22 and the second protection circuit 24 synchronously output the same protection signal, and ensure the synchronization of the actions of the first switch circuit 21 and the second switch. Specifically, the VI pins of the first protection circuit 22 and the second protection circuit 24 are both connected to the back gold layer 1 of the first field effect transistor 211, and / or the VI pins of the first protection circuit 22 and the second protection circuit 24 are both connected to the back gold layer 1 of the second field effect transistor 212.

[0058] In some embodiments, please refer to Figures 1 to 7 , the first switch circuit 21 and the second switch circuit 23 are connected in series with the same electrode of the single battery 10. For example, both the first switch circuit 21 and the second switch circuit 23 are connected in series with the positive electrode of the battery CELL, or both the first switch circuit 21 and the second switch circuit 23 are connected in series with the negative electrode of the battery CELL.

[0059] In some embodiments, the second switch circuit 23 includes electrical components having a switching function and a control port. For example, the second switch circuit 23 may include two triodes connected in series, and the control ports of the two triodes are respectively connected to the DSG pin and the CHG pin in the second battery management chip U2 to obtain protection signals through the DSG pin and the CHG pin respectively, and control the on / off of the two triodes based on the protection signals.

[0060] In some embodiments, referring to Figure 7 and Figure 9 , the second switch circuit 23 may include a third field effect transistor 231, a fourth field effect transistor 232, a third diode 233, and a fourth diode 234. The third field effect transistor 231 and the fourth field effect transistor 232 are respectively connected to the second protection circuit 24. Outside the battery CELL, along the current flow direction, the fourth field effect transistor 232 and the third field effect transistor 231 are connected in sequence. Along the current direction, the fourth diode 234 is connected in parallel with the fourth field effect transistor 232, and along the reverse current direction, the third diode 233 is connected in parallel with the third field effect transistor 231. Specifically, the drain of the fourth field effect transistor 232 is connected to the drain of the third field effect transistor 231; the gate of the third field effect transistor 231 is connected to the DSG pin to obtain the protection signal of the second battery management chip U2, and control its own on / off based on the protection signal to complete the charge and discharge protection of the battery CELL; the third diode 233 is connected in parallel between the source and the drain of the third field effect transistor 231, and the flow direction of the third diode 233 is from the source to the drain of the third field effect transistor 231; the gate of the fourth field effect transistor 232 is connected to the CHG pin to obtain the protection signal of the second battery management chip U2, and control its own on / off based on the protection signal to cooperate with the third field effect transistor 231 to complete the charge and discharge protection of the battery CELL; the fourth diode 234 is connected in parallel between the source and the drain of the fourth field effect transistor 232, and the flow direction of the fourth diode 234 is from the source to the drain of the fourth field effect transistor 232.

[0061] In some embodiments, referring to Figure 4 , Figure 6 and Figure 7 , the VI pin of the first battery management chip U1 in the first protection circuit 22 and the VI pin of the second battery management chip U2 in the second protection circuit 24 are both connected to the back gold layer 1 in the second protection circuit 24 to uniformly detect the input of signals, ensure that the first protection circuit 22 and the second protection circuit 24 synchronously output the same protection signal, and ensure the synchronization of the actions of the first switch circuit 21 and the second switch. Specifically, the VI pins of the first protection circuit 22 and the second protection circuit 24 are both connected to the back gold layer 1 of the third field effect transistor 231, and / or the VI pins of the first protection circuit 22 and the second protection circuit 24 are both connected to the back gold layer 1 of the fourth field effect transistor 232.

[0062] In some embodiments, referring to Figures 1 to 6 , the secondary battery provided by the embodiment of the present application further includes an anti-counterfeiting function circuit 30. The anti-counterfeiting function circuit 30 is connected in parallel with the single battery 10, and the anti-counterfeiting function circuit 30 is communicatively connected to the output terminal 50 of the battery protection board 20 to perform anti-counterfeiting verification on the secondary battery. Exemplarily, the anti-counterfeiting function circuit 30 includes an electronic identification chip, an EEPROM (Electrically Erasable Programmable Read-Only Memory), an encryption algorithm and an authentication module, and an anti-tampering circuit. Among them, the electronic identification chip has a unique serial number or identification code for identifying the authenticity and genuineness of the battery protection board 20, is integrated on the battery protection board 20, and is connected to the main control chip (such as a microcontroller) or a dedicated authentication chip of the battery protection board 20; the EEPROM is used to store anti-counterfeiting data, authentication keys and other necessary information, and the EEPROM is connected to the main control chip of the battery protection board 20; the encryption algorithm and the authentication module are used to encrypt and decrypt the data stored in the EEPROM to ensure data security and the authenticity of the battery protection board 20, and the encryption algorithm and the authentication module are integrated inside the main control chip or connected as an external module; the anti-tampering circuit includes physical enclosures, fusing circuits, anti-tampering labels, etc., for preventing illegal copying and tampering, and the anti-tampering circuit is connected to the pins or peripheral circuits of the main control chip of the battery protection board 20 to ensure that it can be detected and its normal operation can be blocked when the battery protection board 20 is opened or modified.

[0063] In some embodiments, referring to Figures 1 to 6 , the secondary battery provided by the embodiment of the present application further includes a temperature detection circuit 40. The temperature detection circuit 40 is connected in parallel with the single battery 10, and the temperature detection circuit 40 is communicatively connected to the output terminal 50 of the battery protection board 20 to perform temperature detection on the secondary battery. Exemplarily, the temperature detection circuit 40 includes an NTC thermistor (Negative Temperature Coefficient thermistor), and the NTC thermistor is connected to the analog input pin of the main control chip of the battery protection board 20, and the changing resistance value is converted into a voltage signal through a resistor voltage division circuit or an operational amplifier circuit.

[0064] In some embodiments, the first protection circuit 22 determines whether the charging and discharging of the battery is abnormal based on the voltage data of the back gold layer 1, and after the charging and discharging is abnormal, controls the on-off of the first field effect transistor 211 by outputting a protection signal to the gate to control the on-off of the charging and discharging circuit of the single battery 10, so as to realize the charging and discharging protection of the single battery 10.

[0065] Understandably, the secondary battery provided by the embodiments of the present application includes a single battery 10 and a battery protection board 20. The battery protection board 20 includes a first switch circuit 21 and a first protection circuit 22. The first switch circuit 21 is connected in series with the single battery 10. The first switch circuit 21 includes a first field-effect transistor 211. The first protection circuit 22 is connected to the back gold layer 1 of the first field-effect transistor 211 and is also connected to the gate of the first field-effect transistor 211. The present application uses the back gold layer 1 of the field-effect transistor to replace the precision resistor, which can reduce the design of the precision resistor in the battery protection board 20, reduce the design area of electrical components, and reduce the area of the battery protection board 20, so as to reduce the influence of the size of the battery protection board 20 on the size of the battery.

[0066] Correspondingly, the embodiments of the present application further provide an electrical device, including the secondary battery as in the embodiments of the present application.

[0067] In some embodiments, the electrical device provided by the embodiments of the present application may include, but is not limited to, 3C devices such as computers, mobile phones, and tablets.

[0068] The above has introduced in detail a secondary battery and an electrical device provided by the embodiments of the present application. Specific examples are used in this article to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those skilled in the art, according to the idea of the present application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A secondary battery, characterized in that: include: A single cell (10); A battery protection board (20), the battery protection board (20) comprising: A first switch circuit (21), the first switch circuit (21) being connected in series with the single battery (10); the first switch circuit (21) comprising a first field effect transistor (211); A first protection circuit (22), wherein the first protection circuit (22) is respectively connected to the back gold layer (1) and the gate of the first field effect transistor (211).

2. The secondary battery according to claim 1, characterized in that: The first protection circuit (22) is connected in parallel with the single battery (10).

3. The secondary battery according to claim 1, characterized in that: The first switch circuit (21) further comprises: a second field effect transistor (212), wherein the gate of the second field effect transistor (212) is connected to the first protection circuit (22), and the drain of the second field effect transistor (212) is connected to the drain of the first field effect transistor (211); a first diode (213), the first diode (213) being connected in parallel to the source and drain of the first field effect transistor (211), and the flow direction of the first diode (213) is from the source to the drain of the first field effect transistor (211); A second diode (214), the second diode (214) is connected in parallel to the source and drain of the second field effect transistor (212), and the flow direction of the second diode (214) is from the source to the drain of the second field effect transistor (212).

4. The secondary battery according to claim 3, characterized in that: The battery protection board (20) also includes: A second switch circuit (23), the second switch circuit (23) being connected in series with the first switch circuit (21); A second protection circuit (24), wherein the second protection circuit (24), the first protection circuit (22) and the single battery (10) are connected in parallel; the second protection circuit (24) is connected to the second switch circuit (23) to adjust the on and off of the second switch circuit (23).

5. The secondary battery according to claim 4, characterized in that: The first switch circuit (21) and the second switch circuit (23) are connected in series with the same electrode of the single battery (10).

6. The secondary battery according to claim 4, characterized in that: The second switch circuit (23) comprises: A third field effect transistor (231), wherein a gate of the third field effect transistor (231) is connected to the second protection circuit (24); a fourth field effect transistor (232), wherein the gate of the fourth field effect transistor (232) is connected to the second protection circuit (24), and the drain of the fourth field effect transistor (232) is connected to the drain of the third field effect transistor (231); A third diode (233), the third diode (233) being connected in parallel to the source and drain of the third field effect transistor (231), and the flow direction of the third diode (233) is from the source to the drain of the third field effect transistor (231); A fourth diode (234), the fourth diode (234) is connected in parallel to the source and drain of the fourth field effect transistor (232), and the flow direction of the fourth diode (234) is from the source to the drain of the fourth field effect transistor (232).

7. The secondary battery according to claim 6, characterized in that: The first protection circuit (22) and the second protection circuit (24) are both connected to the back gold layer (1) of the first field effect transistor (211), and / or the first protection circuit (22) and the second protection circuit (24) are both connected to the back gold layer (1) of the second field effect transistor (212); Alternatively, the first protection circuit (22) and the second protection circuit (24) are both connected to the back gold layer (1) of the third field effect transistor (231), and / or the first protection circuit (22) and the second protection circuit (24) are both connected to the back gold layer (1) of the fourth field effect transistor (232).

8. The secondary battery according to claim 1, characterized in that: The battery protection board (20) further comprises an anti-counterfeiting functional circuit (30), and the anti-counterfeiting functional circuit (30) is connected in parallel with the single battery (10).

9. The secondary battery according to claim 1, characterized in that: The battery protection board (20) further comprises a temperature detection circuit (40), and the temperature detection circuit (40) is connected in parallel with the single battery (10).

10. An electrical device, characterized in that: The invention comprises the secondary battery according to any one of claims 1 to 9.

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