CN213878179U - Soft package lithium ion battery with exhaust valve - Google Patents
Soft package lithium ion battery with exhaust valve Download PDFInfo
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- CN213878179U CN213878179U CN202120074604.6U CN202120074604U CN213878179U CN 213878179 U CN213878179 U CN 213878179U CN 202120074604 U CN202120074604 U CN 202120074604U CN 213878179 U CN213878179 U CN 213878179U
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
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- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
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Abstract
The utility model provides a soft packet of lithium ion battery with discharge valve, including electric core body, plastic-aluminum membrane and discharge valve subassembly, the plastic-aluminum membrane forms installing zone and air pocket through the pit, electric core body sets up in the installing zone of plastic-aluminum membrane, the both ends of electric core body are equipped with anodal ear and negative pole ear respectively, anodal ear and negative pole ear set up the outside at the plastic-aluminum membrane air pocket, the utmost point ear of anodal ear and negative pole ear glues and is connected with the plastic-aluminum membrane installing zone through the heat-seal, air pocket one side heat-seal forms the installing port, discharge valve subassembly passes through the hot melt adhesive with the installing port and is connected, realize the inside and the outside of discharge valve subassembly intercommunication air pocket. The utility model discloses a battery carries out the pre-charge technology of shallow discharge cycle of shallowly filling again after being full of the electricity for the first time, makes the unnecessary lithium ion in negative pole piece surface inlay the positive pole again to inlay the lithium process back to the positive pole through the pre-charge negative pole, further solve the battery and precharge process negative pole piece surface and analyse the phenomenon of lithium.
Description
Technical Field
The utility model belongs to soft packet of lithium ion battery field especially relates to a soft packet of lithium ion battery with discharge valve.
Background
With the gradual maturity of the technical development of lithium ion batteries and the advocation of new energy automobiles by the state, the automobile industry also begins to increase the requirements on high energy density and light weight of the lithium ion batteries, wherein the soft package lithium ion batteries have the advantages of high energy density, light weight and low cost, and the industrialization of the new energy automobiles is promoted. The pre-charging after the liquid injection aging of the soft package lithium ion battery is the main stage of gas generation in the battery charging and discharging process. The gas in the battery is gradually increased in the pre-charging process and temporarily stored in the air bag of the formed aluminum-plastic film and the gap between the pole piece and the diaphragm. With the increase of the pre-charging time and the increase of the charging current, pre-charging gas cannot be discharged in time, so that lithium is separated from the surface of a pole piece in the charging process, an SEI film is formed unstably, the electrical performance of the battery is seriously influenced, the self-discharge of the battery is large, and even potential safety hazards are caused. Therefore, how to discharge the internal gas in time during the pre-charging process of the battery is very important; the existing technical scheme is that the soft package lithium ion battery with the safety valve is characterized in that the safety valve is installed in the middle of a positive electrode lug and a negative electrode lug and comprises a safety valve outer shell, a stud, a compression spring, a sealing steel ball and hot melt glue, the stud is installed at the head of an inner cavity of the outer shell, the compression spring is arranged below the stud, the compression spring is assembled in a valve body, the bottom of the valve body is sealed by the steel ball, the hot melt glue is laid outside the outer shell, and the stud and the safety valve shell are in clearance fit. The hot melt adhesive of the outer shell is sealed with the upper and lower aluminum plastic films through heat sealing. When gas is generated inside the battery, the elasticity of a spring inside the safety valve can be overcome after the certain pressure is reached, and the gas is released from the safety valve, so that the gas is not gathered inside the battery, the service life of the battery is prolonged, and the safety coefficient of the battery is improved. However, when the safety valves are applied to the soft package lithium ion battery, certain probability of water barrier failure exists, the assembly space of battery groups is limited, the pressure of rupture exhaust is generally high, and the timely discharge of the pre-charge produced gas of the soft package battery for the first time cannot be realized.
The prior art has the following disadvantages: 1. the hot melt adhesive of the safety valve outer shell is heat-sealed with the upper and lower aluminum plastic films, so that certain probability of water barrier failure exists; 2. the safety valve is arranged between the positive electrode lug and the negative electrode lug to form a part of a battery structure, and the assembly space of the module is limited in the battery group assembly process; 3. the rupture exhaust pressure of the explosion type safety valve is generally higher, and the timely discharge of the first pre-charge produced gas of the soft package battery cannot be realized; 4. the explosion safety valve cannot discharge gas generated in the pre-charging process in time, so that the problem that the pre-charging gas is temporarily stored in a formed aluminum plastic film air bag and a gap between a pole piece and a diaphragm, lithium is separated from the surface of the pole piece, the SEI film is unstable, the performance of the electrical property of the battery is influenced, the self-discharge of the battery is large, and potential safety hazards are caused; 5. at present, the pre-charging process of the soft package battery mostly adopts low-current constant-current charging to 20-30% of SOC or low-current constant-current charging, and the back embedding of redundant lithium on the surface of a negative plate can not be realized after full-charge and discharge to 20-30% of SOC.
SUMMERY OF THE UTILITY MODEL
In view of this, the utility model aims at providing a soft packet of lithium ion battery with discharge valve adopts the battery to carry out the pre-charging technology of shallow discharge cycle of shallowly filling again after being full of the electricity for the first time, makes the unnecessary lithium ion in negative pole piece surface inlay the positive pole again to inlay the lithium process to the positive pole through the pre-charging negative pole, further solve the battery and precharge the phenomenon that the lithium was analysed on process negative pole piece surface.
In order to achieve the above purpose, the technical scheme of the utility model is realized like this:
a soft package lithium ion battery with an exhaust valve comprises a battery cell body, an aluminum plastic film and an exhaust valve assembly,
the plastic-aluminum membrane forms installing zone and air pocket through the dash pot, electric core body sets up in the installing zone of plastic-aluminum membrane, the both ends of electric core body are equipped with anodal ear and negative pole ear respectively, anodal ear and negative pole ear set up the outside at the plastic-aluminum membrane air pocket, the utmost point ear of anodal ear and negative pole ear is glued and is connected with the plastic-aluminum membrane installing zone through the heat-seal, air pocket one side heat-seal forms the installing port, the exhaust valve subassembly passes through the hot melt adhesive with the installing port and is connected, realize the inside and the outside of exhaust valve subassembly intercommunication air pocket.
Further, the thickness of the positive electrode tab is 0.5mm, the thickness of the negative electrode tab is 0.3mm, and the model of the battery cell body is 118 AH; the positive electrode lug and the negative electrode lug are fixedly connected to the battery cell body through ultrasonic welding.
Further, the exhaust valve assembly comprises an exhaust valve outer shell, a stud and hot melt adhesive, one side of the mounting opening serves as an upper aluminum-plastic film, the other side of the mounting opening serves as a lower aluminum-plastic film, one side of the exhaust valve outer shell is connected to the upper aluminum-plastic film through the hot melt adhesive, and the other side of the exhaust valve outer shell is connected to the lower aluminum-plastic film through the hot melt adhesive, so that the exhaust valve assembly is fixedly connected with the aluminum-plastic films; the middle part of the exhaust valve outer shell is provided with a threaded hole, and the stud is in threaded connection with the threaded hole to realize the connection of the stud and the exhaust valve outer shell.
Furthermore, the top of the stud is provided with a nut which provides a stress point for the wrench.
Furthermore, the bottom of the stud is of a step structure, the bottom of the threaded hole is provided with a groove, the outer diameter of the step structure is matched with the inner diameter of the groove, the step structure is matched with the groove, and the circumferential surface of the step structure and the inner surface of the threaded hole are provided with a sealing ring.
Furthermore, the thickness of the hot melt adhesive is 150 +/-10 um, and the thickness of the upper aluminum-plastic film and the lower aluminum-plastic film is 153 +/-10 um.
Further, the inner diameter of a threaded hole of the exhaust valve outer shell is 16mm +/-0.1 mm; the outer diameter of the stud is 16mm +/-0.2 mm; the outer diameter of the nut is 10mm +/-0.2 mm; the inner diameter of the sealing ring is 12mm +/-0.2 mm, and the outer diameter is 16mm +/-0.2 mm.
Furthermore, the material of discharge valve shell body is aluminium, and the material of sealing washer is rubber.
Compared with the prior art, a soft packet of lithium ion battery with discharge valve have following advantage:
(1) the utility model relates to a soft packet of lithium ion battery with discharge valve, discharge valve design are the aluminium material, install in shaping plastic-aluminum membrane air pocket one side, are used for exhausting in the process of charging in advance, and after the evacuation heat-seal was ended in the advance, remove together with discharge valve, have avoided the space restriction because of moisture separation inefficacy and the battery assembly process in groups that the installation relief valve brought.
(2) The utility model relates to a soft packet of lithium ion battery with discharge valve has realized the timely discharge of the inside gas production of precharge process, makes positive negative pole piece and diaphragm fully contact, has avoided the phenomenon of pole piece surface lithium analysis, forms stable SEI membrane, has reduced the self-discharge of battery.
(3) The utility model discloses the design and the shaping plastic-aluminum membrane air pocket phase-match of using light, aluminium material's discharge valve have avoided the short circuit risk that causes with the plastic-aluminum membrane heat-seal simultaneously.
(4) The utility model discloses a battery carries out the pre-charge technology of shallow discharge cycle of shallowly filling again after being full of the electricity for the first time, makes the unnecessary lithium ion in negative pole piece surface inlay the positive pole again to inlay the lithium process back to the positive pole through the pre-charge negative pole, further solve the battery and precharge process negative pole piece surface and analyse the phenomenon of lithium.
(5) The utility model discloses the inside sealing washer that increases of discharge valve has improved the outside casing of discharge valve and the leakproofness that the double-screw bolt carries out the gomphosis through the screw thread, has reduced the probability that the moisture separation became invalid.
(6) The utility model discloses the outside hot melt adhesive of discharge valve makes relief valve and ectonexine plastic-aluminum membrane realize better heat sealability, has improved the leakproofness of battery, has reduced the potential safety hazard that the battery brought because of moisture gets into.
Drawings
The accompanying drawings, which form a part hereof, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention without undue limitation. In the drawings:
fig. 1 is a schematic diagram of a soft-package lithium ion battery with an exhaust valve according to an embodiment of the present invention;
fig. 2 is a cross-sectional view of an exhaust valve assembly according to an embodiment of the present invention.
Description of reference numerals:
1. a cell body; 2. an aluminum-plastic film; 21. an upper aluminum-plastic film; 22. a lower aluminum-plastic film layer; 3. a vent valve assembly; 31. an exhaust valve outer shell; 32. a stud; 33. hot melt adhesive; 34. a nut; 35. a seal ring; 4. a positive tab; 5. and a negative tab.
Detailed Description
It should be noted that, in the present invention, the embodiments and features of the embodiments may be combined with each other without conflict.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are used merely for convenience of description and for simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be construed as limiting the present invention. Furthermore, the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.
In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art through specific situations.
The present invention will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.
A soft package lithium ion battery with an exhaust valve comprises a battery cell body 1, an aluminum plastic film 2 and an exhaust valve component 3,
aluminium-plastic film 2 forms installing zone and air pocket through the pit, electric core body 1 sets up in aluminium-plastic film 2's installing zone, electric core body 1's both ends are equipped with anodal ear 4 and negative pole ear 5 respectively, anodal ear 4 and negative pole ear 5 set up the outside at aluminium-plastic film 2 air pockets, anodal ear 4 and negative pole ear 5's utmost point ear glue is connected with aluminium-plastic film installing zone through the heat-seal, air pocket one side heat-seal forms the installing port, discharge valve subassembly 3 passes through the hot melt adhesive with the installing port and is connected, realize discharge valve subassembly 3 intercommunication air pocket inside and outside.
The thickness of the positive tab 4 is 0.5mm, the thickness of the negative tab 5 is 0.3mm, and the model number of the battery cell body 1 is 118 AH; the positive electrode tab 4 and the negative electrode tab 5 are both fixedly connected to the cell body 1 through ultrasonic welding.
The exhaust valve assembly 3 comprises an exhaust valve outer shell 31, a stud 32 and hot melt adhesive 33, one side of the mounting opening is used as an upper-layer aluminum-plastic film 21, the other side of the mounting opening is used as a lower-layer aluminum-plastic film 22, one side of the exhaust valve outer shell 31 is connected to the upper-layer aluminum-plastic film 21 through the hot melt adhesive 33, the other side of the exhaust valve outer shell 31 is connected to the lower-layer aluminum-plastic film 22 through the hot melt adhesive 33, and the exhaust valve assembly 3 is fixedly connected with the aluminum-plastic film 2; the middle part of the exhaust valve outer shell 31 is provided with a threaded hole, and the stud 32 is connected to the threaded hole in a threaded mode, so that the stud 32 is connected with the exhaust valve outer shell 31.
The nut 34 which provides a stress point for a wrench is arranged at the top of the stud 32, and the nut 34 is acted by a torque wrench, so that the purpose of quickly loosening the stud 32 is achieved, the timely discharge of the gas generated in the pre-charging process is realized, the positive and negative pole pieces are fully contacted with the diaphragm, the phenomenon of lithium precipitation on the surfaces of the pole pieces is avoided, a stable SEI film is formed, and the self-discharge of the battery is reduced.
The bottom of the stud 32 is of a step structure, the bottom of the threaded hole is provided with a groove, the outer diameter of the step structure is matched with the inner diameter of the groove, the step structure is matched with the groove, and the circumferential surface of the step structure and the inner surface of the threaded hole are provided with a sealing ring 35.
The thickness of the hot melt adhesive 33 is 150 +/-10 um, and the thicknesses of the upper aluminum plastic film 21 and the lower aluminum plastic film 22 are both 153 +/-10 um.
The inner diameter of a threaded hole of the exhaust valve outer shell 31 is 16mm +/-0.1 mm; the outer diameter of the stud 32 is 16mm +/-0.2 mm; the outer diameter of the nut 34 is 10mm +/-0.2 mm; the inner diameter of the sealing ring 35 is 12mm +/-0.2 mm, and the outer diameter is 16mm +/-0.2 mm.
The material of discharge valve shell body 31 is aluminium, and the design of the discharge valve of matter light, aluminium material and 2 air pockets phase-matches of shaping plastic-aluminum membrane, has avoided simultaneously with the short circuit risk that the 2 heat-sealings of plastic-aluminum membrane caused, and the material of sealing washer 35 is rubber.
A pre-charging method of soft package lithium ion battery with an exhaust valve comprises the following steps,
s1, pre-sealing the soft package lithium ion battery with the exhaust valve after liquid injection, and standing the battery at high temperature for 3 minutes to obtain a battery cell after liquid injection and high-temperature aging;
s2, charging the battery cell after liquid injection and high-temperature aging for 60min at a constant current of 0.05C until the voltage reaches 3.6V, and stopping the charge to 5800 mAh; charging with 0.1C current for 90min to 3.8V and termination capacity of 23200mAh for 3 min, charging with 0.2C current for 240min to 4.2V and cutoff current of 5800mA and termination capacity of 139200 mAh; standing for 3 minutes;
s3, discharging at constant current of 0.2C for 150min to 3.9V, stopping the discharge at 139200mAh, and standing for 3 min; constant-current constant-voltage charging is carried out for 240min at the current of 0.2C until the voltage is 4.35V, the current is cut off to 5800mA, the termination capacity is 139200mAh, and the mixture is stood for 3 min;
s4, discharging at constant current of 0.5C for 150min to 2.5V, stopping the capacity to 139200mAh, standing for 3 min, then discharging at constant current of 0.33C for 30min to 2.5V, stopping the capacity to 139200mAh, standing for 2 min;
s5, charging for 36min at a constant current of 0.5C until the voltage is 3.8V, and stopping the charging to 34800 mAh; standing for 2 minutes; completing the pre-charging;
and S6, in the process of pre-charging the battery, discharging most of gas in the battery through the exhaust valve assembly 3, puncturing the upper edge of the aluminum-plastic film air bag by a gas extractor for residual gas, vacuumizing for exhausting, thermally sealing the interface of the aluminum-plastic film mounting area and the air bag after gas is discharged, then cutting off the air bag part of the aluminum-plastic film 2 after a final sealing machine is used for thermally sealing the interface of the aluminum-plastic film mounting area and the air bag, and obtaining the battery which is subjected to gas exhaust after pre-charging and final sealing.
The process flow for the pre-fill is shown in the table below,
TABLE 1
Example 1:
respectively and reliably connecting the positive tab 4 with the thickness of 0.5mm and the negative tab 5 with the thickness of 0.3mm with the aluminum foil and the copper foil of the battery cell by using an ultrasonic welding machine, realizing the balance of heat production and heat dissipation in the charging and discharging process of the battery, and performing top side sealing by using a packaging machine to obtain a packaged battery cell;
after the packaged battery core is baked and injected with liquid, pre-sealing is carried out, the exhaust valve component 3 is installed on one side of the air bag of the formed aluminum-plastic film 2, and after the pre-filling is finished and the vacuum heat sealing is carried out, the exhaust valve component 3 and the battery are removed, so that the space limitation of battery group assembly and the risk of water separation failure caused by poor heat sealing of the exhaust valve component 3 and the aluminum-plastic film 2 are avoided; the semi-circular end socket is used for carrying out hot melt sealing on a hot melt adhesive 33 (the thickness of the hot melt adhesive is 155um) outside an outer shell (the inner diameter is 15.9mm) of the exhaust valve assembly 3, an upper aluminum-plastic film 21 (the thickness is 153um) and a lower aluminum-plastic film 22 (the thickness is 153um) and a sealing ring 35 is additionally arranged, a torque wrench is used for twisting a nut 34 (the outer diameter of the nut 34 is 10.1mm), so that a stud 32 (the outer diameter is 16.15mm) is tightly embedded with the shell (the inner diameter is 15.9mm) of the exhaust valve assembly 3, the sealing performance of the exhaust valve assembly 3 is improved, better moisture barrier property is realized, the risks of lithium precipitation and self discharge on the surface of a negative plate are reduced, the battery is subjected to high-temperature standing, and the electric core after liquid injection and high-temperature aging is obtained;
increase the thickness of the outside hot melt adhesive 33 of 3 shells of discharge valve subassembly, make hot melt adhesive 33 and ectonexine plastic-aluminum membrane 2 can carry out the heat-seal better, reduced the risk of excessive melting, improved discharge valve subassembly 3 and ectonexine plastic-aluminum membrane 2's leakproofness to reduce the probability that the moisture separation became invalid, reduce the hidden danger that lithium was analysed on negative pole piece surface, improve the electrical property of battery.
The battery core after liquid injection and high temperature aging adopts a pre-charging process flow as shown in Table 1, and is charged to 4.2V by using a small current step constant current of 0.05C, 0.1C and 0.2C, then discharged to 3.9V and charged to 4.35V by using a current constant of 0.2C, and then discharged to 2.5V by using a step constant current of 0.5C and 0.33C, and then charged to 3.8V by using a current constant of 0.5C for pre-charging, so that gas generated in the battery is timely discharged in the pre-charging process, the positive and negative pole pieces are fully contacted with the diaphragm, and meanwhile, the process of embedding lithium from the negative pole to the positive pole by using a shallow-charging and shallow-discharging process is utilized, the phenomenon of lithium precipitation on the surface of the negative pole piece is avoided, a stable SEI film is formed, the self-discharge of the battery is reduced, and the electrical property of the battery is improved.
Example 2:
respectively and reliably connecting the positive electrode tab 4 (with the thickness of 0.5mm) and the negative electrode tab 5 (with the thickness of 0.3mm) with an aluminum foil and a copper foil of the battery cell by using an ultrasonic welding machine, realizing the balance of heat production and heat dissipation in the charging and discharging process of the battery, and performing top side sealing by using a packaging machine to obtain a packaged battery cell;
after the packaged battery core is baked and injected with liquid, pre-sealing is carried out, the exhaust valve component 3 is installed on one side of the air bag of the formed aluminum-plastic film 2, and after the pre-filling is finished and the vacuum heat sealing is carried out, the exhaust valve component 3 and the battery are removed, so that the space limitation of battery group assembly and the risk of water separation failure caused by poor heat sealing of the exhaust valve component 3 and the aluminum-plastic film 2 are avoided; the semi-circular end socket is used for carrying out hot melt sealing on a hot melt adhesive 33 (the thickness of the hot melt adhesive is 145um) outside an outer shell (the inner diameter is 15.9mm) of the exhaust valve assembly 3, an upper aluminum-plastic film 21 (the thickness is 153um) and a lower aluminum-plastic film 22 (the thickness is 153um) and a sealing ring 35 is additionally arranged, a torque wrench is used for twisting a nut 34 (the outer diameter of the nut 34 is 10.1mm), so that a stud 32 (the outer diameter is 16.0mm) is tightly embedded with the shell (the inner diameter is 15.9mm) of the exhaust valve assembly 3, the sealing performance of the exhaust valve assembly 3 is improved, better moisture barrier property is realized, the risks of lithium precipitation and self-discharge on the surface of a negative plate are reduced, the battery is subjected to high-temperature standing, and the battery core after liquid injection and high-temperature aging is obtained;
the external diameter of the stud 32 is reduced, so that the internal diameter of the outer shell of the exhaust valve assembly 3 is better embedded and connected with the external diameter of the stud 32 through threads, the sealing performance of the exhaust valve assembly 3 is improved, the risk of water blocking failure is reduced, the self-discharge of the battery is reduced, and the electrical performance of the battery is improved.
The battery core after liquid injection and high temperature aging adopts a pre-charging process flow as shown in Table 1, and is charged to 4.2V by using a small current step constant current of 0.05C, 0.1C and 0.2C, then is discharged to 3.9V to 4.35V by using a current constant of 0.2C, and then is discharged to 2.5V by using a step constant current of 0.5C and 0.33C, and then is charged to 3.8V by using a current constant of 0.5C for pre-charging, so that gas generated in the battery is timely discharged in the pre-charging process of the battery, the positive and negative pole pieces are fully contacted with the diaphragm, and meanwhile, the process of embedding lithium back to the positive pole by using the negative pole of the shallow charging and shallow discharging process avoids the phenomenon of lithium precipitation on the surface of the negative pole piece, forms a stable SEI film, reduces the self-discharge of the battery, and improves the electrical property of the battery;
example 3:
respectively and reliably connecting the positive electrode tab 4 (with the thickness of 0.5mm) and the negative electrode tab 5 (with the thickness of 0.3mm) with an aluminum foil and a copper foil of the battery cell by using an ultrasonic welding machine, realizing the balance of heat production and heat dissipation in the charging and discharging process of the battery, and performing top side sealing by using a packaging machine to obtain a packaged battery cell;
after the packaged battery core is baked and injected with liquid, pre-sealing is carried out, the exhaust valve component 3 is installed on one side of the air bag of the formed aluminum-plastic film 2, and after the pre-filling is finished and the vacuum heat sealing is carried out, the exhaust valve component 3 and the battery are removed, so that the space limitation of battery group assembly and the risk of water separation failure caused by poor heat sealing of the exhaust valve component 3 and the aluminum-plastic film 2 are avoided; the semi-circular end socket is used for carrying out hot melt sealing on a hot melt adhesive 33 (the thickness of the hot melt adhesive is 145um) outside an outer shell (the inner diameter is 15.9mm) of the exhaust valve assembly 3, an upper aluminum-plastic film 21 (the thickness is 153um) and a lower aluminum-plastic film 22 (the thickness is 153um) and a sealing ring 35 is additionally arranged, a torque wrench is used for twisting a nut 34 (the outer diameter of the nut 34 is 10.1mm), so that a stud 32 (the outer diameter is 16.15mm) is tightly embedded with the shell (the inner diameter is 15.9mm) of the exhaust valve assembly 3, the sealing performance of the exhaust valve assembly 3 is improved, better moisture barrier property is realized, the risks of lithium precipitation and self-discharge on the surface of a negative plate are reduced, the battery is subjected to high-temperature standing, and the battery core after liquid injection and high-temperature aging is obtained;
the battery core after liquid injection and high temperature aging adopts a pre-charging process flow as shown in Table 1, and is charged to 4.2V by using a small current step constant of 0.05C, 0.1C and 0.2C, then discharged to 3.9V by using a current constant of 0.2C, circulated for 2 times, recharged to 4.35V, discharged to 2.5V by using a step constant of 0.5C and 0.33C, then charged to 3.8V by using a current constant of 0.5C, pre-charged, and discharged in time in the pre-charging process of the battery, so that positive and negative plates are fully contacted with a diaphragm, and meanwhile, the process of embedding lithium from the negative electrode to the positive electrode by using a shallow-charging and shallow-discharging process negative electrode avoids the phenomenon of lithium precipitation on the surface of the negative electrode plate, forms a stable SEI film, reduces the self-discharge of the battery, and improves the electrical property of the battery;
the preferred embodiment:
respectively and reliably connecting the positive electrode tab 4 (with the thickness of 0.5mm) and the negative electrode tab 5 (with the thickness of 0.3mm) with an aluminum foil and a copper foil of the battery cell by using an ultrasonic welding machine, realizing the balance of heat production and heat dissipation in the charging and discharging process of the battery, and performing top side sealing by using a packaging machine to obtain a packaged battery cell;
after the packaged battery core is baked and injected with liquid, pre-sealing is carried out, the exhaust valve component 3 is installed on one side of the air bag of the formed aluminum-plastic film 2, and after the pre-filling is finished and the vacuum heat sealing is carried out, the exhaust valve component 3 and the battery are removed, so that the space limitation of battery group assembly and the risk of water separation failure caused by poor heat sealing of the exhaust valve component 3 and the aluminum-plastic film 2 are avoided; the semi-circular end socket is used for carrying out hot melt sealing and adding a sealing ring 35 through a hot melt adhesive 33 (the thickness of the hot melt adhesive is 145um) outside an outer shell (the inner diameter is 15.9mm) of the exhaust valve assembly 3, an upper aluminum-plastic film 21 (the thickness is 153um) and a lower aluminum-plastic film 22 (the thickness is 153um), a torque wrench is used for twisting a nut 34 (the outer diameter of the nut 34 is 10.1mm), so that a stud 32 (the outer diameter is 16.15mm) is tightly embedded with the shell (the inner diameter is 15.9mm) of the exhaust valve assembly 3, the sealing performance of the exhaust valve assembly 3 is improved, better moisture barrier property is realized, the risks of lithium precipitation and self-discharge on the surface of a negative pole piece are reduced, the battery is subjected to high-temperature standing, and the battery core after liquid injection and high-temperature aging is obtained;
the battery core after liquid injection and high temperature aging adopts a pre-charging process flow as shown in Table 1, and is charged to 4.2V by using a small current step constant current of 0.05C, 0.1C and 0.2C, then is discharged to 3.9V to 4.35V by using a current constant of 0.2C, and then is discharged to 2.5V by using a step constant current of 0.5C and 0.33C, and then is charged to 3.8V by using a current constant of 0.5C for pre-charging, so that gas generated in the battery is timely discharged in the pre-charging process of the battery, the positive and negative pole pieces are fully contacted with the diaphragm, and meanwhile, the process of embedding lithium back to the positive pole by using the negative pole of the shallow charging and shallow discharging process avoids the phenomenon of lithium precipitation on the surface of the negative pole piece, forms a stable SEI film, reduces the self-discharge of the battery, and improves the electrical property of the battery;
comparative example 1:
respectively and reliably connecting the positive electrode tab 4 (with the thickness of 0.5mm) and the negative electrode tab 5 (with the thickness of 0.3mm) with an aluminum foil and a copper foil of the battery cell by using an ultrasonic welding machine, realizing the balance of heat production and heat dissipation in the charging and discharging process of the battery, and performing top side sealing by using a packaging machine to obtain a packaged battery cell;
after the battery core is baked and injected with liquid, pre-sealing is carried out to prevent external moisture from entering, and the battery is subjected to high-temperature standing to obtain a liquid-injected high-temperature aged battery core; the electric core after liquid injection aging adopts a conventional pre-charging process, and is subjected to step constant current charging to 4.2V by using small currents of 0.05C, 0.1C and 0.2C, and then is subjected to constant current discharging to 3.0V by using a constant current of 0.5C, and the pre-charging is finished;
comparing the first-effect, discharge capacity, DCR and pressure drop data of the batteries of the examples 1-3 and the battery of the comparative example 1, the soft package lithium ion battery with the exhaust valve assembly 3 and the pre-charging method thereof are provided by the examples 1-3, the exhaust valve assembly 3 is arranged on one side of the air bag of the formed aluminum-plastic film 2, the air bag and the exhaust valve assembly 3 are removed after the pre-charging and the vacuum pumping are finished, and the moisture barrier failure caused by the installation of the exhaust valve assembly 3 and the space limitation of the battery grouping assembly process are avoided; the design of the light-weight and aluminum exhaust valve component 3 is matched with the air bag of the formed aluminum-plastic film 2, and meanwhile, the short circuit risk caused by heat sealing with the aluminum-plastic film 2 is avoided; a sealing ring 35 is added in the structure of the exhaust valve component 3, and meanwhile, the shell of the exhaust valve component 3 is tightly embedded and connected with the stud 32 through threads, so that the sealing property of the exhaust valve component 3 is improved, and the risk of water barrier failure is reduced; the structure of the exhaust valve assembly 3 is added, so that the timely discharge of the gas generated in the pre-charging process is realized, the positive and negative pole pieces are fully contacted with the diaphragm, the phenomenon of lithium precipitation on the surfaces of the pole pieces is avoided, a stable SEI film is formed, and the self-discharge of the battery is reduced. After the battery is fully charged for the first time, shallow charging and shallow discharging circulation is carried out, so that redundant lithium ions on the surface of the negative plate are embedded back to the positive electrode, and the phenomenon of lithium precipitation on the surface of the negative plate in the pre-charging process of the battery is further solved through the process of embedding lithium back to the positive electrode from the pre-charged negative electrode.
The first effect, discharge capacity, DCR, voltage drop data and full-current disassembly interface of the soft-package lithium ion batteries using the preferred embodiment, examples 1-3 and comparative example 1 were compared, and the specific results are shown in the following table,
TABLE 2
As can be seen from the data in table 2, the first efficiency of the soft-package lithium ion battery with the exhaust valve assembly 3, which is fully charged and then subjected to the shallow charging and shallow discharging cycle in the preferred embodiment and embodiments 1 to 3, is improved by 2.6%, 2.8%, 3.1% and 4.4% respectively compared with that of the soft-package lithium ion battery without the exhaust valve assembly 3 and which adopts the conventional pre-charging process; the discharge capacity is respectively improved by 344 mAh, 710 mAh, 126 mAh and 720 mAh; the DCR is respectively reduced by 0.0481, 0.066, 0.545 and 0.1242m omega; the pressure drop was reduced by 0.345, 0.375, 0.335, 0.46mV respectively.
The noun explains:
1. definition of SEI film: during the first charge and discharge of the lithium ion battery, a passivation film is formed between an electrode material and an electrolyte solution, the passivation film has the characteristics of a solid electrolyte, is an electron insulator and is an excellent conductor of Li +, and Li + can be freely inserted and extracted through the passivation layer, so that the passivation film is called a solid electrolyte interface film (SEI).
2. Mechanism of SEI film formation: during the first charge and discharge process of the lithium ion battery, the electrolyte is reduced on the surface of the negative electrode, and insoluble reduction products are precipitated on the surface of the negative electrode material to form a layer of passive film, namely a solid electrolyte interface film. This film is mainly composed of an inorganic layer and an organic layer. The main components are inorganic substances such as Li F and Li2CO3 and organic substances such as alkyl ester lithium on the surface of the electrode.
The voltage at which the SEI film starts to be formed is not fixed, and may be 2V, 1V, or 0.8V; also, the SEI film is continuously formed during charge and discharge cycles of the battery. The formation of the SEI film is related to many factors, for example, a negative electrode material, an electrolyte composition, an additive, a charge rate, and the like.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (8)
1. The utility model provides a soft packet of lithium ion battery with discharge valve which characterized in that: comprises a cell body, an aluminum plastic film and an exhaust valve assembly,
the plastic-aluminum membrane forms installing zone and air pocket through the dash pot, electric core body sets up in the installing zone of plastic-aluminum membrane, the both ends of electric core body are equipped with anodal ear and negative pole ear respectively, anodal ear and negative pole ear set up the outside at the plastic-aluminum membrane air pocket, the utmost point ear of anodal ear and negative pole ear is glued and is connected with the plastic-aluminum membrane installing zone through the heat-seal, air pocket one side heat-seal forms the installing port, the exhaust valve subassembly passes through the hot melt adhesive with the installing port and is connected, realize the inside and the outside of exhaust valve subassembly intercommunication air pocket.
2. The soft-package lithium ion battery with the exhaust valve according to claim 1, wherein: the thickness of the positive tab is 0.5mm, the thickness of the negative tab is 0.3mm, and the model of the battery cell body is 118 AH; the positive electrode lug and the negative electrode lug are fixedly connected to the battery cell body through ultrasonic welding.
3. The soft-package lithium ion battery with the exhaust valve according to claim 1, wherein: the exhaust valve assembly comprises an exhaust valve outer shell, a stud and hot melt adhesive, one side of the mounting port serves as an upper-layer aluminum-plastic film, the other side of the mounting port serves as a lower-layer aluminum-plastic film, one side of the exhaust valve outer shell is connected to the upper-layer aluminum-plastic film through the hot melt adhesive, and the other side of the exhaust valve outer shell is connected to the lower-layer aluminum-plastic film through the hot melt adhesive, so that the exhaust valve assembly is fixedly connected with the aluminum-plastic film; the middle part of the exhaust valve outer shell is provided with a threaded hole, and the stud is in threaded connection with the threaded hole to realize the connection of the stud and the exhaust valve outer shell.
4. The soft-package lithium ion battery with the exhaust valve according to claim 3, wherein: the top of the stud is provided with a nut which provides a stress point for the wrench.
5. The soft-package lithium ion battery with the exhaust valve according to claim 3, wherein: the bottom of the stud is of a step structure, the bottom of the threaded hole is provided with a groove, the outer diameter of the step structure is matched with the inner diameter of the groove, the step structure is matched with the groove, and the circumferential surface of the step structure and the inner surface of the threaded hole are provided with sealing rings.
6. The soft-package lithium ion battery with the exhaust valve according to claim 3, wherein: the thickness of the hot melt adhesive is 150 +/-10 um, and the thickness of the upper aluminum-plastic film and the lower aluminum-plastic film is 153 +/-10 um.
7. The soft-package lithium ion battery with the exhaust valve according to claim 5, wherein: the inner diameter of a threaded hole of the exhaust valve outer shell is 16mm +/-0.1 mm; the outer diameter of the stud is 16mm +/-0.2 mm; the outer diameter of the nut is 10mm +/-0.2 mm; the inner diameter of the sealing ring is 12mm +/-0.2 mm, and the outer diameter is 16mm +/-0.2 mm.
8. The soft-package lithium ion battery with the exhaust valve according to claim 5, wherein: the material of discharge valve shell body is aluminium, and the material of sealing washer is rubber.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114204205A (en) * | 2021-12-10 | 2022-03-18 | 远景动力技术(江苏)有限公司 | Soft package battery and heat sealing method thereof |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114204205A (en) * | 2021-12-10 | 2022-03-18 | 远景动力技术(江苏)有限公司 | Soft package battery and heat sealing method thereof |
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