Composite pole piece, battery cell and battery
By adopting a composite electrode structure in lithium batteries and sodium batteries, and taking advantage of the fact that the melting point of the insulating base layer is lower than that of the current collector layer, a micro-short circuit self-discharge is formed during thermal runaway, thus solving the problem of battery spontaneous combustion and improving the safety performance of the battery.
Patent Information
- Application Number
- CN202422649597.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-30
- Publication Date
- 2025-10-21
- Estimated Expiration
- 2034-10-30
AI Technical Summary
Existing lithium batteries and sodium batteries lack effective prevention mechanisms in the event of thermal runaway, which can easily lead to spontaneous combustion and affect safety performance.
A composite pole piece structure is adopted, including an insulating base layer, a first and a second current collector layer, and an active material layer. The melting point of the insulating base layer is lower than that of the current collector layer. In the event of thermal runaway, it melts first to form a micro-short circuit, causing the battery to self-discharge, thereby avoiding further heat release and spontaneous combustion.
The micro-short circuit mechanism allows the battery to self-discharge, preventing thermal runaway from developing into spontaneous combustion and improving battery safety performance.
Smart Images
Figure CN223462235U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of battery preparation, and in particular to a composite electrode sheet, a battery cell and a battery. BACKGROUND
[0002] In the current lithium battery and sodium battery field, the core structure involves positive electrode materials, negative electrode materials, electrolytes, separators and current collectors and other key components. In the specific application process, when the battery is in thermal runaway condition, the battery is prone to rapid heating inside the battery, which may cause the separator to shrink, trigger internal short circuit, and eventually evolve into a self-ignition accident.
[0003] In related technologies, when the battery is in thermal runaway due to high temperature environment, there is a lack of effective prevention mechanism, which leads to the battery being prone to develop from thermal runaway to self-ignition, posing a major safety hazard to equipment and personal safety, and affecting the safety performance of the battery. CONTENT OF THE UTILITY MODEL
[0004] To solve or partially solve the problems in the related art, the present application provides a composite electrode sheet, a battery cell and a battery, which can make the battery self-discharge when the external environment or internal environment gradually heats up, thereby making the battery tend to a stable state without electricity, effectively avoiding further heat release and self-ignition of the battery, and improving the safety performance of the battery.
[0005] The first aspect of the present application provides a composite electrode sheet, comprising an insulating base layer, a first current collector layer and a second current collector layer;
[0006] The first current collector layer and the second current collector layer are respectively compounded on both sides of the insulating base layer along the thickness direction; the first current collector layer is provided with a first active material layer on the side away from the insulating base layer, and the second current collector layer is provided with a second active material layer on the side away from the insulating base layer;
[0007] The insulating base layer comprises a first insulating substrate, and the melting point of the first insulating substrate is lower than the melting points of the first current collector layer and the second current collector layer, respectively.
[0008] In some embodiments, the first insulating substrate comprises one or more of HDPE, PP, PE, PI, PET and PVC.
[0009] In some embodiments, the melting point of the first insulating substrate is 90-130℃.
[0010] In some embodiments, the first current collector layer comprises one of copper foil, aluminum foil and nickel foil, and the second current collector layer comprises another of copper foil, aluminum foil and nickel foil.
[0011] In some embodiments, the first active material layer comprises at least one of lithium cobaltate, lithium manganate, lithium iron phosphate; and / or
[0012] The second active material layer comprises at least one of graphite, silicon.
[0013] In some embodiments, the insulating base layer further comprises a second insulating base material, the melting point of the second insulating base material is lower than the melting point of the first insulating base material.
[0014] In some embodiments, the second insulating base material is in a granular form, and the particle size is equal to or greater than the average thickness of the insulating base layer.
[0015] In some embodiments, the proportion of the second insulating base material in the insulating base layer is 5% to 50%.
[0016] The second aspect of the present application provides an electric core prepared by winding or laminating the composite tab and the separator according to the first aspect of the present application.
[0017] The third aspect of the present application provides a battery comprising the electric core according to the second aspect of the present application.
[0018] The technical solution provided by the present application can include the following beneficial effects:
[0019] The technical solution of the present application comprises the following beneficial effects:
[0020] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF DRAWINGS
[0021] The above and other objects, features and advantages of the present application will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout the figures, and in which:
[0022] Figure 1is a structural schematic diagram of a composite pole piece shown in an embodiment of the present application;
[0023] Figure 2 is a state schematic diagram of a composite pole piece shown in an embodiment of the present application;
[0024] Figure 3 is another structural schematic diagram of a composite pole piece shown in an embodiment of the present application;
[0025] Figure 4 is another state schematic diagram of a composite pole piece shown in an embodiment of the present application.
[0026] The reference signs: 100, insulating base layer; 110, first insulating base material; 120, second insulating base material; 200, first current collector layer; 300, second current collector layer; 400, first active material layer; 500, second active material layer. DETAILED DESCRIPTION
[0027] Embodiments of the present application will be described in more detail by referring to the attached drawings. Although embodiments of the present application are shown in the drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present application will be thorough and complete, and will fully convey the scope of the present application to those skilled in the art.
[0028] It should be understood that although the terms "first", "second", "third", etc. can be used in this application to describe various information, these information should not be limited by these terms. These terms are only used to distinguish the same type of information from each other. For example, the first information can also be referred to as the second information, and similarly, the second information can also be referred to as the first information without departing from the scope of the present application. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited. It should also be understood that the term "and / or" used herein means and includes any or all possible combinations of one or more associated listed items.
[0029] In the description of the present application, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.
[0030] Unless specifically stated otherwise, and unless otherwise dictated by the strict inherent requirements of the specification, the terms "mounting", "connected", "connecting", "fixed", and the like, are to be construed broadly, for example, they can be fixed connections, or detachable connections, or integral; they can be mechanical connections, or electrical connections; they can be direct connections, or indirect connections through an intermediate medium, or the internal communication of two elements, or the interaction relationship between two elements. For those skilled in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.
[0031] In the related art, when the battery is subjected to a high-temperature environment and thermal runaway occurs, there is a lack of effective prevention mechanism, which leads to the battery being prone to develop from thermal runaway to spontaneous combustion, posing a major hidden danger to equipment and personal safety, and affecting the safety performance of the battery.
[0032] To solve the above problems, the application embodiment provides a composite tab, which can make the battery self-discharge when the external environment or the internal environment gradually warms up, and thus make the battery tend to a stable state without electricity, effectively avoiding further heat release and spontaneous combustion of the battery, and improving the safety performance of the battery.
[0033] The technical solutions of the application embodiments are described in detail below with reference to the accompanying drawings.
[0034] Figure 1 is a structural schematic diagram of the composite tab shown in the application embodiment.
[0035] Referring to Figure 1 The composite tab of the application includes an insulating base layer 100, a first current collector layer 200, and a second current collector layer 300.
[0036] The first current collector layer 200 and the second current collector layer 300 are respectively compounded on both sides of the insulating base layer 100 along the thickness direction. The compounding between the insulating base layer 100, the first current collector layer 200, and the second current collector layer 300 can be achieved by a gluing compounding method. The side of the first current collector layer 200 away from the insulating base layer 100 is provided with a first active material layer 400, and the side of the second current collector layer 300 away from the insulating base layer 100 is provided with a second active material layer 500.
[0037] The insulating base layer 100 includes a first insulating base material 110, and the melting point of the first insulating base material 110 is lower than the melting point of the first current collector layer 200 and the melting point of the second current collector layer 300, respectively. It can be understood that the first insulating base material 110 can be used as the main material for preparing the insulating base layer 100.
[0038] Figure 2 is a state schematic diagram of the composite tab shown in the application embodiment.
[0039] Referring to Figure 2When the composite tab of the present application is applied to the battery cell, in the case of gradual temperature rise in the external environment or the internal environment, since the melting point of the first insulating base material 110 is lower than the melting point of the first current collector layer 200 and the melting point of the second current collector layer 300, it can be known that the main material of the insulating base layer 100, the first insulating base material 110, will first melt under heat, causing the area of the insulating base layer 100 to collapse, so that the first current collector layer 200 and the second current collector layer 300 corresponding to the collapsed position are directly contacted or indirectly contacted through the electrolyte, forming a micro-short circuit of the battery cell, so as to make the battery cell self-discharge.
[0040] It should be noted that since the edge of the tab may have manufacturing defects, damage or stress concentration, etc. Unfavorable, when the battery is in thermal runaway, the common trigger point of thermal runaway is generally at the edge of the tab, and then the area of thermal runaway spreads from the edge to the center. In the process of thermal runaway of the battery, the insulating base layer 100 starts to melt from the edge, and the first current collector layer 200 and the second current collector layer 300 are directly contacted or contacted through the electrolyte at the corresponding edge position, and then the area of thermal runaway spreads from the edge to the center, and the insulating base layer 100 at the corresponding area is subjected to corresponding heat melting process to make the first current collector layer 200 and the second current collector layer 300 contact short circuit at the corresponding position. Of course, the trigger point of battery thermal runaway may also spread from the center to the edge, and when the insulating base layer 100 at the corresponding area melts, the first current collector layer 200 and the second current collector layer 300 at the corresponding position can still be contacted and short-circuited.
[0041] It can be understood that in the case of thermal runaway of the battery, the charged battery will cause various chemical reactions and electrochemical reactions inside the battery, and the composite tab of the present application can make the battery tend to be in a stable state without electricity by forming a micro-short circuit of the battery cell and self-discharging the battery, thereby effectively preventing the battery from further releasing heat and self-igniting, and effectively improving the safety performance of the battery. In addition, the insulating base layer 100 can consume part of the heat energy inside the battery during the melting process, further preventing the battery from heating up sharply, and ensuring the safety of the battery in use.
[0042] In some embodiments, the melting point of the first insulating substrate 110 can be 90-130°C. In the present application, the melting point of the first insulating substrate 110 is 90-130°C, so that the first insulating substrate 110 has a more reasonable melting point range, so that a faster response can be made when the battery is in thermal runaway during the battery thermal runaway process, to achieve a more rapid prevention of the thermal runaway of the battery from continuing to occur, and at the same time can prevent the melting point of the first insulating substrate 110 from being too low, effectively guaranteeing the stability of the battery in normal scenarios. In some specific embodiments, the thickness of the insulating substrate 100 can be 2-20μm, so that the thickness of the insulating substrate 100 will not be too thick to affect the melting efficiency of the insulating substrate 100 when the battery is in thermal runaway.
[0043] The first current collector layer 200 and the first active material layer 400 can correspond to the positive electrode or the negative electrode in the battery cell, and the second current collector layer 300 and the second active material layer 500 can correspond to the electrode of the other polarity in the battery cell. For example, the first current collector layer 200 and the first active material layer 400 correspond to the positive electrode, and the second current collector layer 300 and the second active material layer 500 correspond to the negative electrode.
[0044] In some embodiments, the first current collector layer 200 can include one of a copper foil, an aluminum foil, and a nickel foil, and the second current collector layer 300 can include another of the copper foil, the aluminum foil, and the nickel foil. It should be understood that the positive electrode and the negative electrode in the battery cell need to use current collector materials suitable for different potentials, respectively. When the first current collector layer 200 corresponds to the positive electrode, the first current collector layer 200 can use an aluminum foil material, and the second current collector layer 300 corresponds to the negative electrode and uses a copper foil material.
[0045] In some embodiments, the first active material layer 400 can correspond to the positive electrode of the battery cell. The first active material layer 400 can include at least one of lithium cobaltate, lithium manganate, and lithium iron phosphate. The second active material layer 500 can correspond to the negative electrode of the battery cell. The second active material layer 500 can include at least one of graphite and silicon.
[0046] In some embodiments, the first insulating substrate 110 can include one or more of HDPE (high-density polyethylene), PP (polypropylene), PE (polyethylene), PI (polyimide), PET (polyethylene terephthalate), and PVC (polyvinyl chloride). It should be understood that the six different types of plastic materials, HDPE (high-density polyethylene), PP (polypropylene), PE (polyethylene), PI (polyimide), PET (polyethylene terephthalate), and PVC (polyvinyl chloride), have different melting points. In order to make the above-mentioned materials suitable for rapid melting during thermal runaway of the battery, the melting points of the six different types of plastic materials can be reduced to a suitable range by modifying the above-mentioned materials, so that the first insulating substrate 110 made of the above-mentioned materials can have better insulation performance while rapidly melting during thermal runaway of the battery to form a micro-short circuit self-discharge inside the battery, further ensuring the safety performance of the battery. Of course, materials other than the above-mentioned six plastic materials can also be used to prepare the first insulating substrate 110 to achieve the corresponding insulation and low melting point effect, which is not limited here.
[0047] Figure 3 is another structural schematic diagram of the composite pole piece shown in the embodiments of the present application; Figure 4 is another state schematic diagram of the composite pole piece shown in the embodiments of the present application.
[0048] Referring to Figure 3 and Figure 4 In some embodiments, the insulating base layer 100 can also include a second insulating substrate 120. It can be understood that the insulating base layer 100 can be prepared by mixing the first insulating substrate 110 and the second insulating substrate 120. The melting point of the second insulating substrate 120 is lower than that of the first insulating substrate 110. That is, under the same gradual temperature rise, the second insulating substrate 120 will melt before the first insulating substrate 110 because the melting point of the second insulating substrate 120 is lower than that of the first insulating substrate 110. By additionally using the second insulating substrate 120 with a lower melting point than the first insulating substrate 110, the insulating base layer 100 can realize a two-stage melting mechanism during thermal runaway of the battery. Specifically, the second insulating substrate 120 is first melted by heat to form a smaller area of collapse of the insulating base layer 100, causing the battery to micro-short circuit. During the continuous gradual temperature rise, the first insulating substrate 110 is melted following the temperature rise, further expanding the collapse area of the insulating base layer 100, thereby increasing the short circuit area between the first current collector layer and the second current collector layer and increasing the degree of short circuit self-discharge of the battery. Through the above process, the self-discharge control process of the battery during thermal runaway is more stable, thereby strengthening the suppression effect of the battery in the case of severe temperature rise.
[0049] In some embodiments, the second insulating substrate accounts for 5% to 50% in the insulating base layer. Specifically, the proportion of the second insulating substrate 120 in the insulating base layer 100 can be less than or equal to the proportion of the first insulating substrate 110 in the insulating base layer 100.
[0050] In yet some embodiments, the second insulating substrate 120 can be in a granular form, and the particle size of the second insulating substrate 120 is equal to or greater than the average thickness of the insulating base layer 100. It can be understood that when the particle size of the second insulating substrate 120 is equal to or greater than the average thickness of the insulating base layer 100, the second insulating substrate 120 can form an electronic channel penetrating through the insulating base layer 100 in the thickness direction after being melted, i.e., the first current collector layer 200 and the second current collector layer 300 are in direct contact or indirect contact through electrolyte on the corresponding electronic channel, thereby forming a stable micro-short circuit effect.
[0051] In order to further understand the technical solutions of the present application, the following introduces the main four kinds of battery short circuit modes in the battery thermal runaway model, which include: positive electrode current collector and negative electrode current collector, positive electrode current collector and negative electrode active material layer, positive electrode active material layer and negative electrode current collector, and positive electrode active material layer and negative electrode active material layer.
[0052] According to Joule's law, the heat Q generated by the current passing through the conductor is proportional to the square of the current I, proportional to the resistance R of the conductor, and proportional to the time t of the current, i.e., Q=I²Rt. In the above four short circuit situations, taking the positive electrode current collector as an aluminum foil, the positive electrode active material layer as a lithium cobalt oxide film, the negative electrode current collector as a copper foil, and the negative electrode active material layer as a graphite film, and the contact area diameter is 7mm as an example, the contact resistances of the four short circuit situations are shown in Table 1 as follows:
[0053]
[0054] Table 1
[0055] From the content of Table 1 above, it can be known that when the positive electrode aluminum current collector and the negative electrode copper current collector are short-circuited, the heat generated during the short-circuit discharge of the two is small due to the small contact resistance, and it is not easy to cause severe temperature rise and other adverse effects on the battery product.
[0056] The present application also provides a battery cell, which comprises the aforementioned composite electrode plate and the separator wound or laminated. It can be understood that the composite electrode plate of the present application can be used for the preparation of wound battery cells or laminated battery cells.
[0057] The present application also provides a battery, which comprises the aforementioned battery cell.
[0058] In order to make the application more easily understood, the manufacturing process of the battery of the present application will be further described in detail below in conjunction with the embodiments, which are only illustrative and are not limited to the scope of the application. The raw materials or components used in the present application can be prepared by commercial or conventional methods if not otherwise specified.
[0059] Embodiment 1
[0060] S110, preparing an insulating base layer from modified PET, and performing glue coating treatment on both sides of the insulating base layer, and then respectively compositing copper foil current collector and aluminum foil current collector on both sides of the insulating base layer to form a base material to be coated;
[0061] S120, coating negative electrode material on the side of the base material corresponding to the copper foil current collector;
[0062] S130, coating positive electrode material on the other side of the base material corresponding to the aluminum foil current collector to obtain a composite electrode sheet;
[0063] S140, preparing a battery according to the composite electrode sheet.
[0064] Embodiment 2
[0065] S210, coating negative electrode material on one side of the copper foil current collector, and coating positive electrode material on one side of the aluminum foil current collector;
[0066] S220, respectively compositing the coated copper foil current collector and the coated aluminum foil current collector to both sides of the insulating base layer prepared from modified PET to obtain a composite electrode sheet;
[0067] S230, preparing a battery according to the composite electrode sheet.
[0068] Embodiment 3
[0069] S310, compositing copper foil current collector to one side of the insulating base layer prepared from modified PET, and coating negative electrode material on the copper foil current collector;
[0070] S320, coating positive electrode material on one side of the aluminum foil current collector;
[0071] S330, compositing the coated aluminum foil current collector to the other side of the insulating base layer to obtain a composite electrode sheet;
[0072] S340, preparing a battery according to the composite electrode sheet.
[0073] The solutions of the present application have been described in detail above with reference to the accompanying drawings. In the above examples, the description of each example is focused on respectively, and the parts not described in detail in a certain example can be referred to the relevant description of other examples. It should also be known by those skilled in the art that the actions and modules involved in the specification are not necessarily required by the present application. In addition, it can be understood that the steps in the method of the embodiments of the present application can be adjusted, combined and reduced in sequence according to actual needs, and the modules in the device of the embodiments of the present application can be combined, divided and reduced according to actual needs.
[0074] The above has described various embodiments of the present application, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical application or improvement of technology in the market, or to enable other ordinary skilled in the art to understand the embodiments disclosed herein.
Claims
1. A composite pole piece characterized by, The composite electrode plate comprises an insulating base layer, a first current collector layer and a second current collector layer. The first current collector layer and the second current collector layer are respectively compounded on both sides of the insulating base layer along the thickness direction; the first active material layer is arranged on the side of the first current collector layer away from the insulating base layer, and the second active material layer is arranged on the side of the second current collector layer away from the insulating base layer. The insulating base layer comprises a first insulating base material, and the melting point of the first insulating base material is lower than the melting points of the first current collector layer and the second current collector layer.
2. The composite pole piece of claim 1, wherein, The first insulating base material comprises one or more of HDPE, PP, PE, PI, PET and PVC.
3. The composite pole piece of claim 1, wherein, The melting point of the first insulating base material is 90-130℃.
4. The composite pole piece of claim 1, wherein, The first current collector layer comprises one of copper foil, aluminum foil and nickel foil, and the second current collector layer comprises another one of copper foil, aluminum foil and nickel foil.
5. The composite pole piece of claim 1, wherein, The first active material layer comprises one of lithium cobaltate, lithium manganate and lithium iron phosphate; and / or The second active material layer comprises one of graphite and silicon.
6. The composite pole piece of any one of claims 1 to 5, wherein, The insulating base layer further comprises a second insulating base material, and the melting point of the second insulating base material is lower than the melting point of the first insulating base material.
7. The composite pole piece of claim 6, wherein, The second insulating base material is in a granular form, and the particle size is equal to or greater than the average thickness of the insulating base layer.
8. The composite pole piece of claim 6, wherein, The proportion of the second insulating base material in the insulating base layer is 5-50%.
9. An electric cell characterized by The composite electrode plate and the separator are prepared by winding or laminating.
10. A battery, characterized by The electric core comprises the electric core of claim 9.