CN117810580A

CN117810580A - Secondary battery and packaging method thereof

Info

Publication number: CN117810580A
Application number: CN202311864229.5A
Authority: CN
Inventors: 周明炯; 司佳
Original assignee: Ningbo University
Current assignee: Ningbo University
Priority date: 2023-12-29
Filing date: 2023-12-29
Publication date: 2024-04-02

Abstract

The invention discloses a secondary battery, which comprises a pole piece group, a pole lug, a shell and a diaphragm; the sensor is used for detecting the environmental factors inside the shell, and a joint of the sensor extends out of the shell and is in communication connection with monitoring equipment. In the invention, the sensor is arranged in the shell of the secondary battery, when the parameters of the internal environmental factors of the secondary battery are abnormal, the sensor can timely sense, and the sensed signals are transmitted to the alarm system outside the secondary battery through the sensor connector, so that the alarm system outputs an alarm to prevent the occurrence of safety accidents. Compared with the prior art that the sensor is arranged outside the secondary battery, the built-in sensor can timely sense abnormal parameters inside the secondary battery, so that safety accidents are effectively prevented.

Description

Secondary battery and packaging method thereof

Technical Field

The invention relates to the field of batteries, in particular to a secondary battery and a packaging method thereof.

Background

Along with the increasing demands of people on consumer electronic products and electric automobiles, secondary batteries (such as lithium ion batteries, sodium ion batteries and the like) are widely applied to the fields of mobile terminals of mobile phones, cameras, electric automobiles and the like due to the advantages of small volume, light weight, high specific capacity and the like. A typical secondary battery includes a case, a pole piece group disposed in the case, and the like. In the charge and discharge process, the internal defect factors of the secondary battery can cause the internal temperature of the secondary battery to rise, so that the problems of electrolyte decomposition, electrode material decomposition, oxidation and the like are caused, and serious safety accidents such as fire and explosion are caused.

The existing monitoring equipment can monitor the state parameters such as the temperature, the voltage, the current and the like of the secondary battery in real time, and perform on-line fault diagnosis based on the monitored state parameters, and once faults occur, if the temperature of the secondary battery is too high and the current exceeds a set rated threshold value, the monitoring equipment can give an alarm processing instruction.

However, the sensor in the conventional monitoring device is generally provided outside the secondary battery, and when an abnormality occurs inside the secondary battery, the external sensor cannot detect in time. Such as a temperature sensor, the heat conduction rate is slow due to the temperature difference between the regions inside the secondary battery. The temperature sensor cannot timely find out the temperature abnormality inside the secondary battery.

Therefore, how to detect the occurrence of an abnormality in the secondary battery in time, thereby preventing the occurrence of a safety accident, is a critical problem to be solved by those skilled in the art.

Disclosure of Invention

In view of the above, an object of the present invention is to design a secondary battery that can be detected in time when an abnormality occurs.

In order to achieve the above purpose, the present invention provides the following technical solutions:

a secondary battery comprises a pole piece group, a pole lug, a shell and a diaphragm; the shell is coated outside the pole piece group, the pole piece group comprises a plurality of pole pieces, the plurality of pole pieces are arranged in a mode of sequentially and alternately arranging positive pole pieces and negative pole pieces, the pole lugs comprise positive pole lugs and negative pole lugs, all the positive pole pieces are connected with the positive pole lugs, all the negative pole pieces are connected with the negative pole lugs, and the diaphragms are arranged between the adjacent pole pieces;

the sensor is characterized by further comprising a sensor, wherein the diaphragm is arranged between the pole piece at the most end part and the inner wall of the shell, the diaphragm is an outer diaphragm, the sensor is arranged on the outer diaphragm and is used for detecting environmental factors in the shell, and a connector of the sensor extends out of the shell and is in communication connection with monitoring equipment.

Preferably, the extending direction of the tab is the same as the extending direction of the joint of the sensor.

Preferably, an insulating part is arranged between the tab and the joint of the sensor.

Preferably, the shell comprises two membranes connected with each other, the two membranes are coated outside the pole piece group from two ends of the pole piece group, one edge of the membrane and one edge of the other membrane form a liquid injection port, the tabs and the joints of the sensor extend out of the liquid injection port, the tabs are positioned in the liquid injection port, a partition is arranged between the tabs and the joints of the sensor, the partition forms the insulating part, and at least one part of the partition is positioned in a sealing area of the liquid injection port.

Preferably, the membrane attached to the sensor is turned inwards to form the partition, a notch for the connector of the sensor to penetrate is formed in the partition, and the notch is located in the sealing area of the liquid injection port.

Preferably, the plurality of sensors are arranged on the outer diaphragms at one end, or the plurality of sensors are arranged on the outer diaphragms at two ends respectively, and the joint of each sensor extends out from the corresponding notch.

Preferably, the sensor comprises a temperature sensor and a pressure sensor.

Preferably, the temperature sensor and the pressure sensor are located on the same outer diaphragm, the diaphragm attached to the temperature sensor and the pressure sensor is turned over to the liquid injection port to form the partition, two notches are formed in the partition, the joint of the temperature sensor and the joint of the pressure sensor extend out of the two notches respectively, and the two notches are located in the sealing area of the liquid injection port.

Preferably, the temperature sensor and the pressure sensor are separately arranged on the two outer side diaphragms, the two diaphragms are turned over to the liquid injection port to form two partitions, the two partitions are respectively provided with a notch, the two notches are respectively used for the joint of the temperature sensor and the joint of the pressure sensor to penetrate, and the two notches are located in the sealing area of the liquid injection port.

Preferably, the joint of the temperature sensor is aligned with one of the positive electrode tab and the negative electrode tab, and the joint of the pressure sensor is aligned with the other of the positive electrode tab and the negative electrode tab.

Preferably, the outer surface of the sensor is provided with an anti-corrosion coating, or the outer surface of the sensor is provided with a coating.

Preferably, all the diaphragms are formed by sequentially folding integral diaphragm sheets, and an inserting cavity for inserting one pole piece is formed between two adjacent diaphragms.

The invention provides a packaging method of a secondary battery, which is characterized by comprising the following steps:

s1: punching the two diaphragms, so that the two diaphragms are covered outside the pole piece group, one edge of one diaphragm and one edge of the other diaphragm form the liquid injection port, and the pole lugs extend out of the liquid injection port;

s2: flanging the diaphragm to be attached to the sensor to form the partition, and cutting the notch on the partition;

s3: placing the sensor subjected to corrosion prevention treatment on the outer surface of an outer diaphragm through the liquid injection port, wherein the outer diaphragm and the diaphragm with the notch are positioned at the same end of the pole piece group, so that a joint of the sensor penetrates out of the notch;

s4: injecting electrolyte through the liquid injection port;

s5: and sealing the liquid injection port, fusing the partition with the edges of the two diaphragms, and closing the notch.

From the technical scheme, the following can be seen: in the invention, the sensor is arranged in the shell of the secondary battery, when the parameters of the internal environmental factors of the secondary battery are abnormal, the sensor can timely sense, and the sensed signals are transmitted to the alarm system outside the secondary battery through the sensor connector, so that the alarm system outputs an alarm to prevent the occurrence of safety accidents. Compared with the prior art that the sensor is arranged outside the secondary battery, the built-in sensor can timely sense abnormal parameters inside the secondary battery, so that safety accidents are effectively prevented.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required to be used in the description of the embodiments or the prior art are briefly introduced below, and it is obvious that the drawings in the following description are only embodiments of the present invention, and other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of the positional relationship between a sensor and a pole piece set according to an embodiment of the present invention;

fig. 2 is a schematic view showing the structure of a secondary battery before sealing according to an embodiment of the present invention;

FIG. 3 is a schematic view of a front seal of a seal according to an embodiment of the present invention;

FIG. 4 is a schematic view of a structure of a post-seal according to an embodiment of the present invention;

fig. 5 is a flowchart illustrating a process for manufacturing a secondary battery according to an embodiment of the present invention.

The names of the components in the drawings are as follows:

1-pole piece, 11-positive pole piece, 12-negative pole piece, 2-diaphragm, 3-outside diaphragm, 4-sensor, 41-temperature sensor, 42-pressure sensor, 411-temperature sensor's joint, 421-pressure sensor's joint, 5-tab, 51-positive tab, 52-negative pole tab, 6-diaphragm, 7-incision, 8-liquid filling port, 9-partition.

Detailed Description

In view of this, the core of the present invention is to provide a secondary battery to ensure that the secondary battery can be timely detected when an abnormality occurs.

Another core of the present invention is to provide a method of packaging a secondary battery.

Referring to fig. 1-4, a secondary battery according to an embodiment of the present invention includes a pole piece group, a pole tab 5, a housing, a diaphragm 2, and particularly, a sensor 4.

The pole piece group comprises a plurality of pole pieces 1, wherein one part of the pole pieces 1 is a positive pole piece 11, and the other part is a negative pole piece 12. The positive electrode plates 11 and the negative electrode plates 12 are sequentially and alternately arranged to form a plate group. The shell is coated outside the pole piece group. Tab 5 includes positive tab 51 and negative tab 52, all positive tabs 11 are connected to positive tab 51, and all negative tabs 12 are connected to negative tab 52. The positive tab 51 and the negative tab 52 protrude from the case and are connected to an external device. A separator 2 is provided between two adjacent pole pieces 1, that is, between the adjacent positive pole piece 11 and negative pole piece 12, and the separator 2 insulates the adjacent positive pole piece 11 and negative pole piece 12 from each other. The outside of the pole piece 1 at the extreme end of the pole piece group is also provided with a diaphragm 2, which diaphragm 2 is an outside diaphragm 3. The outer side of the pole piece 1 at the extreme end of the pole piece group, i.e. the side of the pole piece 1 at the extreme end of the pole piece group facing away from the pole piece 1 at the secondary end. The sensor 4 is arranged on the outer diaphragm 3. The outer diaphragm 3 insulates the sensor 4 and the pole piece 1 at the extreme end, and can effectively prevent the sensor 4 from being electrically connected with the pole piece 1 at the extreme end, thereby ensuring that the pole piece 1 and the sensor 4 work normally. The contacts of the sensor 4 extend from the housing and are connected to an external monitoring arrangement.

The sensor 4 is used to detect environmental factors inside the housing, such as temperature, pressure, etc. inside the housing.

In the invention, the sensor 4 is arranged in the shell of the secondary battery, when the parameters of the internal environmental factors of the secondary battery are abnormal, the sensor 4 can sense in time and transmit the sensed signals to the monitoring equipment outside the secondary battery through the connector of the sensor 4, so that the monitoring equipment alarms to prevent the occurrence of safety accidents. Compared with the prior art that the sensor 4 is arranged outside the secondary battery, the built-in sensor 4 in the invention can timely sense abnormal parameters inside the secondary battery, thereby effectively preventing safety accidents.

Since the tabs 5 and the contacts of the sensor 4 are both conductors, they interfere with each other if they are in contact. Therefore, it is possible to choose to have the tab 5 and the joint of the sensor 4 protrude from different directions, with the distance between them as large as possible. However, if the tabs 5 and the contacts of the sensor 4 protrude from different sides of the case, since the tabs 5 of all the secondary batteries face the same direction, a certain space needs to be left between the adjacent two secondary batteries for the contacts of the sensor 4 to be wired, which is disadvantageous for the fixation and tight arrangement of the secondary batteries. The invention therefore preferably leads the tab 5 and the joint of the sensor 4 out of the same side of the housing or the tab 5 and the joint of the sensor 4 extend in the same direction.

In order to insulate the tab 5 led out in the same direction from the joint of the sensor 4, the present invention provides an insulating portion between the tab 5 and the joint of the sensor 4. The housing may particularly preferably be an aluminum plastic film having extremely high mechanical strength and corrosion resistance. The material of the insulating portion may be the same as that of the housing.

The shell comprises two membranes 6 which are connected with each other, the two membranes 6 are respectively arranged at two ends of the pole piece group, and the pole piece group is coated. One edge of one diaphragm 6 and one edge of the other diaphragm 6 form a filling port 8. The tabs 5 and the joints of the sensor 4 extend from the liquid injection port 8. A partition 9 is provided between the tab 5 and the joint of the sensor 4 in the liquid inlet 8, and the partition 9 constitutes an insulating portion for insulating the tab 5 from the joint of the sensor 4. The liquid filling port 8 is closed by sealing. At least a portion of the partition 9 is located in the sealing area of the pouring spout 8, i.e. a portion of the partition 9 is located in the sealing area of the pouring spout 8 or all is located in the sealing area of the pouring spout 8. When the liquid filling port 8 is sealed, the partition 9 is fused with the edges of the two diaphragms 6.

In the prior art, the liquid injection port is sealed by fusing two layers of films. In the present invention, the filling port 8 is sealed by fusing at least three layers of films to each other. The three layers of films are mutually and thermally fused, so that the firmness of sealing can be effectively improved.

Two of the three diaphragms are two diaphragms 6 forming the housing, and the third diaphragm is a partition 9. The number of the sensors 4 may be one or a plurality of. If the sensors 4 are a plurality of sensors, the sensors 4 can be arranged on the same outer diaphragm 3, a partition 9 is arranged between the joints of the sensors 4 and the lugs 5, and in this case, three layers of diaphragms are fused after sealing; the plurality of sensors 4 may be separately provided on the two outer diaphragms 3, and a partition 9 is provided between each sensor 4 and the tab 5, and two partitions 9 are provided in total, in which case four layers of diaphragms are fused after sealing.

After the liquid is injected into the shell through the liquid injection port 8, the inside of the shell needs to be vacuumized through the liquid injection port 8, and along with the vacuumization, the two diaphragms 6 and the partition 9 can be closely attached together. If the partition 9 is a separate piece of membrane, then during the evacuation through the port 8, the partition 9 is likely to deflect away from the port 8, failing to provide effective insulation between the tab 5 and the joint of the sensor 4. For this purpose, the invention is designed as follows: the defining partition 9 is a part of the membrane 6, in particular, the partition 9 is formed by an inward flanging of the pouring spout 8 along the fold line of the membrane 6. After folding, the fold line becomes an edge of the membrane 6 forming the filling port 8. The partition 9 is provided with a slit 7 through which the connector of the sensor 4 passes, and the connector of the sensor 4 passes through the slit 7. In this way, the partition 9 is interposed between the tab 5 and the joint of the sensor 4. During the process of sealing the pouring opening 8, the cut 7 on the partition 9 is closed.

Since the partition 9 is a part of the diaphragm 6, the partition 9 is constrained by other parts of the diaphragm 6, that is, the part of the diaphragm 6 from which the partition 9 is removed locates the partition 9, so that the partition 9 does not deviate from the liquid inlet 8 when a vacuum is drawn through the liquid inlet 8, thereby effectively insulating the joint of the sensor 4 from the tab 5.

In addition, the joint of the sensor 4 passes through the notch 7, the notch 7 forms a constraint on the joint of the sensor 4, and then the notch 7 forms a constraint positioning on the sensor 4. After the liquid is injected into the casing through the liquid injection port 8, the inside of the casing needs to be vacuumized through the liquid injection port 8 so as to extract the redundant electrolyte. Because the sensor 4 is restrained and positioned by the notch 7, the sensor 4 cannot excessively deviate from a preset position in the process of liquid injection or vacuum pumping, so that the sensor 4 is ensured to be positioned on the outer surface of the outer diaphragm 3, and the normal operation of the sensor 4 and the pole piece 1 is ensured.

In the process of charging and discharging the secondary battery, internal defects of the secondary battery can cause the internal temperature of the secondary battery to rise, so that problems such as electrolyte decomposition, electrode material decomposition and oxidization are caused, and serious safety accidents such as fire and explosion are caused. Therefore, the sensor 4 in the present invention includes the temperature sensor 41, and if the temperature sensor 41 detects an abnormality in the internal temperature of the secondary battery, the monitoring device is triggered to alarm.

The sensor 4 may be plural, such as a pressure sensor, a temperature sensor, or the like. The plurality of sensors 4 may be provided on the outer diaphragm 3 at one end, the diaphragm 6 at that end being turned inwardly towards the fill port 8 to form a partition 9, the partition 9 being provided with a plurality of cutouts 7, the joint of each sensor 4 extending from one of the cutouts 7. The plurality of sensors 4 may be separately provided on the outer diaphragms 3 at both ends. For each sensor 4, the membrane 6 of that end is turned inwardly towards the pouring orifice 8 to form a partition 9, the partition 9 being provided with a corresponding number of slits 7, the joint of each sensor 4 protruding from one slit 7.

In the process of charging and discharging the secondary battery, some side reactions are accompanied by the generation of gas, and the secondary battery is internally provided with a closed space, so that the degree of the side reactions can be judged by the change of the internal gas pressure of the secondary battery. Therefore, the sensor 4 of the present invention further includes a pressure sensor 42, and if the pressure sensor 42 detects an abnormality in the internal air pressure of the secondary battery, the monitoring device is triggered to alarm.

The temperature sensor 41 and the pressure sensor 42 may be provided on the same outside diaphragm 3. The diaphragm 6 attached to the temperature sensor 41 and the pressure sensor 42 is turned over to the liquid injection port 8 to form a partition 9, two parallel notches 7 are arranged on the partition 9, the joint 411 of the temperature sensor 41 and the joint 421 of the pressure sensor 42 extend from the two notches 7 respectively, and the two notches 7 are located in the sealing area of the liquid injection port 8. In this embodiment, the insulation between the temperature sensor 41 and the pressure sensor 42 and the tab 5 is achieved by a partition 9. The partition 9 is fused with the sealing of the filling opening 8, and the two cuts 7 in the partition 9 are closed.

The temperature sensor 41 and the pressure sensor 42 may also be separately provided on the two outer diaphragms 3, i.e., the temperature sensor 41 and the pressure sensor 42 are located at both end sides of the pole piece group. In this case, the two diaphragms 6 are turned over towards the liquid injection port 8 to form two partitions 9, the two partitions 9 are respectively provided with a notch 7, the two notches 7 are respectively penetrated by the joint 411 of the temperature sensor 41 and the joint 421 of the pressure sensor 42, and the two notches 7 are both positioned in the sealing area of the liquid injection port 8. In this embodiment, the insulation between the temperature sensor 41 and the pressure sensor 42 and the tab 5 is achieved by two partitions 9, the two partitions 9 being fused with the sealing of the liquid filling opening 8, the two cutouts 7 being closed accordingly.

The connector 411 of the temperature sensor 41 and the connector 421 of the pressure sensor 42 are aligned with the positive electrode tab 51 and the negative electrode tab 52, respectively, and after sealing, two different sensors 4 are easily distinguished, so that data processing is facilitated.

As is apparent from the above description, the separator 2 is provided between the adjacent pole pieces 1 and outside the end-most pole piece 1. If all the separators 2 are independent of each other, the separators 2 are easily deviated from the original positions during the injection of the liquid into the inside of the case or the evacuation of the inside of the case, thus deteriorating the quality of the secondary battery. To solve this problem, the present invention has been devised as follows: defining that all the membrane 2 is formed by folding a membrane sheet. Specifically, a series of fold lines are designed on a diaphragm sheet, the fold lines are arranged at intervals, then the diaphragm sheet is folded along each fold line in turn to form a diaphragm 2, and the folding directions of two adjacent folds are opposite, so that a plurality of diaphragms 2 are formed. An insertion cavity for inserting one pole piece 1 is formed between two adjacent diaphragms 2. Due to the mutual connection and mutual constraint of the plurality of diaphragms 2, the diaphragms 2 cannot deviate from the original positions greatly during liquid injection or vacuum pumping.

The outer separator 3 may be a single-layer separator or a multi-layer separator. The sensor 4 may be provided on the outer surface of the outer diaphragm 3, or the sensor 4 may be embedded between two adjacent diaphragms.

As shown in fig. 5, the secondary battery is manufactured as follows: preparing materials, coating, baking and rolling to form a pole piece 1, cutting pieces and laminating to form a pole piece group, spot welding a pole lug 5, punching a shell, cladding the pole piece group in the shell, flanging a diaphragm 6 to be attached to a sensor 4 to form a partition 9, cutting a notch 7 on the partition 9, putting the sensor 4 subjected to corrosion prevention treatment on a corresponding outer diaphragm 3 through a liquid injection port 8, injecting electrolyte into the shell through the liquid injection port 8, vacuumizing the shell through the liquid injection port 8, pumping out redundant electrolyte, and finally sealing to form a finished secondary battery.

The sensor 4 in the present invention is preferably a thin film type sensor 4. The electrochemical corrosion environment in the secondary battery can cause the problems of structural failure of the sensor 4, corrosion of packaging materials and the like, and the requirements of the secondary battery on long-term stable operation of the sensor 4 in the full life cycle cannot be met. Therefore, the present invention performs corrosion protection treatment on the sensor 4. The anti-corrosion treatment is to provide an anti-corrosion coating layer on the outer surface of the sensor 4, and to provide a coating layer on the outer surface of the sensor 4.

The anti-corrosion treatment process specifically comprises the following steps:

a) Cleaning the surface of the sensor 4 by using acetone, isopropyl alcohol, absolute ethyl alcohol or the like;

b) Drying the sensor 4 by blowing nitrogen or heating and drying in a blast oven;

c) Coating the sensor 4, for example, coating a layer of epoxy resin, polyolefin and the like on the surface of the sensor 4, or depositing silane and the like on the surface of the sensor 4 by using a Chemical Vapor Deposition (CVD) method and the like to form a silicon dioxide film, a silicon nitride film and the like so as to achieve the purpose of corrosion resistance;

or the sensor 4 is coated with a polymer, for example, an organic polymer material film such as a polyimide film is coated on the surface of the sensor 4. Polyimide has excellent thermal stability, chemical corrosion resistance and mechanical properties, and has stable chemical properties, and general polyimide is resistant to chemical solvents such as hydrocarbons, esters, ethers, alcohols, fluorochloroalkanes and the like, wherein esters and ethers are common electrolyte solvents.

The invention discloses a packaging method of a secondary battery, which comprises the following steps:

s1: the two diaphragms 6 are punched, so that the two diaphragms 6 are covered outside the pole piece group, one edge of one diaphragm 6 and one edge of the other diaphragm 6 form a liquid injection port 8, and the pole lug 5 extends out of the liquid injection port 8.

A whole aluminum plastic film is folded along a middle folding line to form two films 6, the left side edges of the two films 6 are punched and sealed, the right side edges of the two films are punched and sealed, the upper side edges of the two films form a liquid injection port 8, and the electrode lugs 5 extend out of the liquid injection port 8. Grooves are provided on the inner walls of the two diaphragms 6 for the placement of pole piece sets.

S2: the diaphragm 6 to be attached to the sensor 4 is turned over to form a partition 9, and a slit 7 is cut in the partition 9.

S3: the sensor 4 subjected to corrosion protection treatment is placed on the outer surface of the outer diaphragm 3 through the liquid injection port 8, and the outer diaphragm 3 and the diaphragm 6 with the notch 7 are positioned at the same end of the pole piece group, so that the joint of the sensor 4 passes out of the notch 7.

If there are two sensors 4 and two sensors 4 are located on the same outer diaphragm 3, then the diaphragm 6 on the same side as the outer diaphragm 3 is turned over to form a partition 9, and two cutouts 7 are machined in the partition 9, and the joints of the two sensors 4 protrude from the two cutouts 7, respectively. If two sensors 4 are provided, and the two sensors 4 are separately arranged on the two outer diaphragms 3, the two diaphragms 6 are respectively turned to form two partitions 9, a notch 7 is respectively processed on the two partitions 9, and joints of the two sensors 4 respectively extend from the similar notches 7.

S4: electrolyte is injected through the liquid injection port 8.

S5: the liquid filling port 8 is sealed, the partition 9 is fused with the edges of the two diaphragms 6, and the notch 7 is closed.

After packaging, the secondary batteries are grouped by 5 or 10, and the sensors 4 in the same group of secondary batteries are connected to the same wireless transmitter. After the secondary batteries are grouped, compared with the secondary batteries which are respectively and independently connected to a wireless transmitter, the secondary batteries are respectively and independently connected to a wireless transmitter, the signal processing amount can be reduced, the signal processing is facilitated to be processed more rapidly, and meanwhile, the accuracy can be ensured. The wireless transmitter is used, so that the wire harness in the secondary battery pack can be reduced, the packaging of the whole secondary battery pack is facilitated, and meanwhile, the wireless transmitter is easy to realize real-time monitoring of the performance of the secondary battery and interconnection and intercommunication among various products.

In the description of the present application, it should be noted that the azimuth or positional relationship indicated by the terms "upper", "lower", "left", "right", etc. are based on the azimuth or positional relationship shown in the drawings, and are merely for convenience of description of the present application and simplification of the description, and do not indicate or imply that the apparatus or element in question must have a specific azimuth, be configured and operated in a specific azimuth, and thus should not be construed as limiting the present application. The terms "first," "second," and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

Unless specifically stated or limited otherwise, the terms "mounted," "connected," and "coupled" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art in a specific context.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A secondary battery comprises a pole piece group, a pole lug (5), a shell and a diaphragm (2); the shell is coated outside the pole piece group, the pole piece group comprises a plurality of pole pieces (1), the pole pieces (1) are sequentially and alternately arranged according to positive pole pieces (11) and negative pole pieces (12), the pole lugs (5) comprise positive pole lugs (51) and negative pole lugs (52), all the positive pole pieces (11) are connected with the positive pole lugs (51), all the negative pole pieces (12) are connected with the negative pole lugs (52), and a diaphragm (2) is arranged between every two adjacent pole pieces (1);

the sensor is characterized by further comprising a sensor (4), wherein the diaphragm (2) is arranged between the pole piece (1) at the most end part and the inner wall of the shell, the diaphragm (2) is an outer diaphragm (3), the sensor (4) is arranged on the outer diaphragm (3), the sensor (4) is used for detecting environmental factors inside the shell, and a connector of the sensor (4) extends out of the shell and is in communication connection with monitoring equipment.

2. The secondary battery according to claim 1, wherein the protruding direction of the tab (5) is the same as the protruding direction of the tab of the sensor (4).

3. The secondary battery according to claim 2, wherein an insulating portion is provided between the tab (5) and the joint of the sensor (4).

4. A secondary battery according to claim 3, wherein the housing comprises two membranes (6) connected with each other, the two membranes (6) are wrapped outside the pole piece group from two ends of the pole piece group, an edge of one membrane (6) and an edge of the other membrane (6) form a liquid injection port (8), the tabs (5) and the joints of the sensor (4) are all protruded from the liquid injection port (8), and a partition (9) is arranged between the tabs (5) and the joints of the sensor (4) in the liquid injection port (8), the partition (9) forms the insulating part, and at least one part of the partition (9) is located in a sealing area of the liquid injection port (8).

5. The secondary battery according to claim 4, wherein the diaphragm (6) attached to the sensor (4) is turned inward toward the liquid inlet (8) to form the partition (9), and the partition (9) is provided with a slit (7) through which a joint of the sensor (4) passes, and the slit (7) is located in a sealing region of the liquid inlet (8).

6. The secondary battery according to claim 5, wherein the plurality of sensors (4) are provided, the plurality of sensors (4) being provided on the outer separator (3) at one end, or the plurality of sensors (4) being provided separately on the outer separators (3) at both ends, the joint of each sensor (4) protruding from the corresponding slit (7).

7. The secondary battery according to claim 6, wherein the sensor (4) includes a temperature sensor (41) and a pressure sensor (42).

8. The secondary battery according to claim 7, wherein the temperature sensor (41) and the pressure sensor (42) are located on the outer side diaphragm (3) at the same end, the diaphragm (6) attached to the temperature sensor (41) and the pressure sensor (42) is turned up toward the liquid injection port (8) to form the partition (9), two notches (7) are provided on the partition (9), and the joint (411) of the temperature sensor (41) and the joint (421) of the pressure sensor (42) protrude from the two notches (7) respectively, and the two notches (7) are located in the sealing area of the liquid injection port (8).

9. The secondary battery according to claim 7, wherein the temperature sensor (41) and the pressure sensor (42) are separately provided on the outer diaphragms (3) at both ends, the two diaphragms (6) are turned up toward the liquid injection port (8) to form two partitions (9), one notch (7) is provided on each of the two partitions (9), the two notches (7) are respectively penetrated by a joint (411) of the temperature sensor (41) and a joint (421) of the pressure sensor (42), and the two notches (7) are located in a sealing area of the liquid injection port (8).

10. The secondary battery according to claim 7, wherein the tab (411) of the temperature sensor (41) is aligned with one of the positive electrode tab (51) and the negative electrode tab (52), and the tab (421) of the pressure sensor (42) is aligned with the other of the positive electrode tab (51) and the negative electrode tab (52).

11. The secondary battery according to claim 1, characterized in that the outer surface of the sensor (4) is provided with an anti-corrosion coating, or the outer surface of the sensor (4) is provided with a coating.

12. The secondary battery according to claim 1, wherein all the diaphragms (2) are folded in sequence by integral diaphragm sheets, and an insertion cavity for inserting one pole piece (1) is formed between two adjacent diaphragms (2).

13. A packaging method of a secondary battery according to claim 5, characterized by comprising:

s1: punching the two diaphragms (6) to enable the two diaphragms (6) to be coated outside the pole piece group, enabling one edge of one diaphragm (6) and one edge of the other diaphragm (6) to form the liquid injection port (8), and enabling the pole lugs (5) to extend out of the liquid injection port (8);

s2: flanging the diaphragm (6) to be attached to the sensor (4) to form the partition, and cutting the notch (7) in the partition;

s3: placing the sensor (4) subjected to corrosion prevention on the outer surface of the outer diaphragm (3) through the liquid injection port (8), wherein the outer diaphragm (3) and the diaphragm (6) with the notch (7) are positioned at the same end of the pole piece group, so that a joint of the sensor (4) penetrates out of the notch (7);

s4: injecting electrolyte through the liquid injection port (8);

s5: sealing the liquid injection port (8), fusing the partition (9) with the edges of the two diaphragms (6), and closing the notch (7) along with the fusion.