Wide-temperature-range protection type lithium battery

Abstract

The utility model relates to a kind of wide temperature range protection type lithium battery, including positive current collector and negative current collector, the positive current collector is equipped with a plurality of first honeycomb hole, the negative current collector is equipped with a plurality of second honeycomb hole, the first honeycomb hole inner wall is coated with positive carbon nanometer capsule layer, the second honeycomb hole inner wall is coated with negative carbon nanometer capsule layer, the positive carbon nanometer capsule layer is coated with positive active material and low temperature ionic liquid, the negative carbon nanometer capsule layer is coated with negative active material and low temperature ionic liquid.The beneficial effects of the utility model lie in that battery low temperature performance can be improved, and the stability of battery at high temperature can also be enhanced.

Description

Technical Field

[0001] This utility model relates to the field of lithium battery technology, specifically to a wide-temperature-range protected lithium battery. Background Technology

[0002] With the development of electric vehicles, aerospace, polar exploration, and other fields, lithium batteries need to maintain stable performance in extreme temperatures ranging from -40°C to 80°C or even wider. However, traditional lithium batteries are prone to problems such as electrolyte solidification and a sharp drop in ionic conductivity at low temperatures, leading to capacity decay and charging difficulties. At high temperatures, the electrode material structure is unstable, and the electrolyte is prone to decomposition, which may cause safety hazards such as thermal runaway. Utility Model Content

[0003] The purpose of this invention is to provide a wide-temperature-range protected lithium battery that can improve the low-temperature performance of the battery and enhance its stability at high temperatures.

[0004] A wide-temperature-range protected lithium battery includes a positive current collector and a negative current collector. The positive current collector has a plurality of first honeycomb pores, and the negative current collector has a plurality of second honeycomb pores. The inner walls of the first honeycomb pores are coated with a positive carbon nanotube layer, and the inner walls of the second honeycomb pores are coated with a negative carbon nanotube layer. The positive carbon nanotube layer encapsulates a positive active material and a low-temperature ionic liquid, and the negative carbon nanotube layer encapsulates a negative active material and a low-temperature ionic liquid.

[0005] In the above scheme, the first and second honeycomb pore structures increase the contact area between the electrode and the electrolyte. When the temperature drops and the internal pressure of the battery exceeds the tolerance limit of the positive and negative carbon nanocapsule layers, the positive and negative carbon nanocapsule layers rupture and release a low-temperature ionic liquid. This liquid has good low-temperature fluidity and ion conductivity, which can effectively reduce the internal resistance of the battery and improve the transport rate of lithium ions between the electrode and the electrolyte. This allows the battery to maintain high charge and discharge efficiency and capacity at low temperatures. The positive and negative carbon nanocapsule layers have certain thermal stability and heat insulation properties. At high temperatures, they can act as a physical barrier to reduce the direct contact between the positive and negative active materials and the electrolyte, thereby reducing the incidence of side reactions. The reduction of side reactions can reduce the heat generation and pressure accumulation inside the battery and prevent thermal runaway.

[0006] Furthermore, both the positive electrode carbon nanocapsule layer and the negative electrode carbon nanocapsule layer have a granular hollow structure at the microscopic level, and the wall thickness of the positive electrode carbon nanocapsule layer and the negative electrode carbon nanocapsule layer is 10-20 nm.

[0007] In the above scheme, the positive and negative carbon nanocapsule layers are microscopically granular and hollow, allowing the positive and negative active materials and the low-temperature ionic liquid to be encapsulated within them. The moderate wall thickness of 10-20 nm ensures the structural integrity of the positive and negative carbon nanocapsule layers without excessively hindering lithium-ion transport. Lithium ions can relatively easily pass through the positive and negative carbon nanocapsule layers of this thickness and migrate rapidly between the electrolyte, positive active material, and negative active material, which helps to improve the charge and discharge efficiency and rate performance of the battery. The low-temperature ionic liquid is [EMIM][TFSI] ionic liquid.

[0008] In the above scheme, the viscosity of traditional electrolytes increases significantly at low temperatures, and even solidification occurs, which seriously affects the conduction of lithium ions. However, [EMIM][TFSI] ionic liquids have good low-temperature fluidity and a low freezing point, and can remain liquid at low temperatures. This allows lithium ions to move freely in the electrolyte, effectively reducing the internal resistance of the battery at low temperatures and improving the charging and discharging efficiency of the battery.

[0009] Furthermore, the diameter of the first and second honeycomb pores is 50-200μm, the pore spacing is 10-50μm, and the first and second honeycomb pores are arranged in an alternating structure when the positive current collector and the negative current collector are superimposed.

[0010] In the above scheme, the pore size of 50-200μm creates a large number of honeycomb pores on the surface of the positive and negative electrode current collectors, which significantly increases the contact area between the electrode and the electrolyte. This means that more active materials can fully contact the electrolyte, thereby accelerating the insertion and extraction process of lithium ions between the electrode and the electrolyte, effectively improving the charging and discharging efficiency of the battery. The pore spacing of 10-50μm ensures that the structural strength of adjacent first honeycomb pores and adjacent second honeycomb pores will not decrease due to being too close, nor will the ion transport efficiency be affected due to being too far apart. The staggered arrangement of the first and second honeycomb pores further optimizes the lithium ion transport path. When the positive and negative electrode current collectors are stacked, this staggered arrangement makes the transport of lithium ions between the positive and negative electrodes more uniform, avoiding the problem of excessive or insufficient local current density.

[0011] Furthermore, the positive electrode active material is NCM811, and the negative electrode active material is a silicon-carbon composite material.

[0012] In the above scheme, NCM811 has a relatively good crystal structure, which is conducive to the insertion and extraction of lithium ions. During the charging and discharging process, lithium ions can diffuse relatively quickly in the NCM811 lattice, reducing the resistance to ion transport and thus improving the charging and discharging efficiency of the battery. The carbon component in the silicon-carbon composite material can not only serve as a supporting framework for silicon, but also has good conductivity. During the charging and discharging process, carbon can quickly conduct electrons, enabling silicon particles to exchange charges with external circuits in a timely manner.

[0013] Furthermore, it also includes a diaphragm wound between the positive current collector and the negative current collector.

[0014] In the above scheme, when the battery is in normal use or subjected to external forces such as vibration and compression, the wound separator can reliably separate the positive and negative electrodes and prevent the direct conduction of electrons, thereby preventing serious safety accidents such as battery overheating, fire or even explosion caused by short circuit, and greatly improving the safety of the battery during use.

[0015] Furthermore, the membrane includes an outer layer, a middle layer, and an inner layer, wherein the outer layer is in contact with the positive current collector, and the inner layer is in contact with the negative current collector.

[0016] In the above scheme, the outer layer is in contact with the positive electrode current collector. During the charging and discharging process, the positive electrode undergoes a relatively complex redox reaction, generating high potential and heat. The outer layer of the separator can be made of materials with good oxidation resistance and thermal stability, which can effectively resist the strong oxidizing environment generated by the positive electrode, prevent side reactions between the positive electrode material and the electrolyte, avoid the dissolution and structural damage of the positive electrode material, thereby improving the safety and cycle life of the battery. The negative electrode may have the risk of lithium metal deposition during charging and discharging, and may react with the electrolyte to form a solid electrolyte interphase (SEI) film. The inner layer of the separator can be made of materials with good lithium metal stability, inhibiting the growth of lithium dendrites, preventing lithium dendrites from piercing the separator and causing a short circuit between the positive and negative electrodes, and reducing the risk of battery thermal runaway. The middle layer can serve as an additional safety barrier. When the outer or inner layer is slightly damaged due to accidents (such as local overheating, mechanical damage, etc.), the middle layer can prevent direct contact between the positive and negative electrodes, further reducing the possibility of short circuit and providing more reliable safety protection for the battery.

[0017] Furthermore, the outer layer is a polyimide-based film with a thickness of 20-30 μm, and the surface is coated with an Al2O3 nanoparticle layer; the middle layer is a SiO2 nanowire-reinforced PE separator with a thickness of 15-20 μm; and the inner layer is a PVDF-HFP gel polymer layer with a thickness of 10-15 μm.

[0018] In the above scheme, the outer polyimide-based film has excellent high-temperature resistance, with high glass transition temperature and thermal decomposition temperature, and can maintain stable physical and chemical properties in high-temperature environments. The inner PVDF-HFP gel polymer layer has good flexibility and stability to lithium metal, and can form a uniform interface layer on the negative electrode surface to inhibit the growth of lithium dendrites. The middle SiO2 nanowire-reinforced PE separator has a unique porous structure and good ion conductivity, which enables lithium ions to migrate quickly and smoothly between the positive and negative electrodes, improving the charge and discharge efficiency and rate performance of the battery.

[0019] This invention discloses a wide-temperature-range protective lithium battery that improves both low-temperature performance and high-temperature stability. The first and second honeycomb pore structures increase the contact area between the electrodes and the electrolyte. When the temperature drops and the internal pressure exceeds the tolerance limit of the carbon nanotube capsule layers, the positive and negative electrode nanotube capsule layers rupture, releasing a low-temperature ionic liquid. This liquid exhibits excellent low-temperature fluidity and ion conductivity, effectively reducing the internal resistance of the battery and increasing the lithium-ion transport rate between the electrodes and the electrolyte. This allows the battery to maintain high charge / discharge efficiency and capacity even at low temperatures. The carbon nanotube capsule layers possess certain thermal stability and insulation properties, acting as a physical barrier at high temperatures to reduce direct contact between the positive and negative electrode active materials and the electrolyte, thus lowering the incidence of side reactions. This reduction in side reactions reduces internal heat generation and pressure accumulation, preventing thermal runaway. Attached Figure Description

[0020] Figure 1 This is a simplified schematic diagram of a wide-temperature-range protected lithium battery according to one embodiment.

[0021] Figure 2 This is a schematic diagram of a positive current collector according to an embodiment.

[0022] Figure 3 This is a schematic diagram of a negative current collector according to an embodiment.

[0023] Figure 4 This is a schematic diagram of a diaphragm according to one embodiment.

[0024] Explanation of reference numerals in the attached figures: 1. Positive current collector; 11. First honeycomb pore; 3. Positive carbon nanocapsule layer; 2. Negative current collector; 21. Second honeycomb pore; 4. Negative carbon nanocapsule layer; 5. Separator; 51. Outer layer; 52. Middle layer; 53. Inner layer. Detailed Implementation

[0025] The following will describe in further detail a wide-temperature-range protected lithium battery according to specific embodiments and accompanying drawings.

[0026] like Figures 1 to 3 As shown in a preferred embodiment, a wide-temperature-range protected lithium battery of the present invention includes a positive current collector 1 and a negative current collector 2. The positive current collector 1 is provided with a plurality of first honeycomb holes 11, and the negative current collector 2 is provided with a plurality of second honeycomb holes 21. The inner wall of the first honeycomb holes 11 is coated with a positive carbon nanotube capsule layer 3, and the inner wall of the second honeycomb holes 21 is coated with a negative carbon nanotube capsule layer 4. The positive carbon nanotube capsule layer 3 is filled with a positive active material and a low-temperature ionic liquid, and the negative carbon nanotube capsule layer 4 is filled with a negative active material and a low-temperature ionic liquid.

[0027] In the above embodiments, when the temperature decreases to the point that the internal pressure of the battery exceeds the tolerance limit of the positive electrode carbon nanocapsule layer 3 and the negative electrode carbon nanocapsule layer 4, the positive electrode carbon nanocapsule layer 3 and the negative electrode carbon nanocapsule layer 4 rupture and release a low-temperature ionic liquid. This liquid has good low-temperature fluidity and ion conductivity, which can effectively reduce the internal resistance of the battery and increase the transport rate of lithium ions between the electrode and the electrolyte. This allows the battery to maintain a high charge and discharge efficiency and capacity at low temperatures. The positive electrode carbon nanocapsule layer 3 and the negative electrode carbon nanocapsule layer 4 have certain thermal stability and heat insulation properties. At high temperatures, they can act as a physical barrier to reduce the direct contact between the positive electrode active material and the negative electrode active material and the electrolyte, thereby reducing the incidence of side reactions. The reduction of side reactions can reduce the heat generation and pressure accumulation inside the battery and prevent thermal runaway.

[0028] Specifically, the first honeycomb hole 11 and the second honeycomb hole 21 structure increases the contact area between the electrode and the electrolyte. The first honeycomb hole 11 and the second honeycomb hole 21 can be realized by 3D printing technology.

[0029] like Figures 1 to 3 As shown, in some embodiments, both the positive electrode carbon nanocapsule layer 3 and the negative electrode carbon nanocapsule layer 4 have a microscopically granular hollow structure, with a wall thickness of 10-20 nm. The microscopically granular and hollow structure of the positive electrode carbon nanocapsule layer 3 and the negative electrode carbon nanocapsule layer 4 allows the positive electrode active material, the negative electrode active material, and the low-temperature ionic liquid to be encapsulated within them. The moderate wall thickness of 10-20 nm ensures the structural integrity of the positive electrode carbon nanocapsule layer 3 and the negative electrode carbon nanocapsule layer 4 without excessively hindering lithium-ion transport. Lithium ions can relatively easily pass through the positive electrode carbon nanocapsule layer 3 and the negative electrode carbon nanocapsule layer 4 of this thickness, rapidly migrating between the electrolyte, the positive electrode active material, and the negative electrode active material, which helps improve the battery's charge / discharge efficiency and rate performance.

[0030] like Figures 1 to 3As shown, in some embodiments, the low-temperature ionic liquid is [EMIM][TFSI] ionic liquid. Traditional electrolytes exhibit significantly increased viscosity and even solidification at low temperatures, severely impacting lithium-ion conduction. In contrast, [EMIM][TFSI] ionic liquids possess excellent low-temperature fluidity and a low freezing point, maintaining a liquid state even at low temperatures. This allows lithium ions to move freely within the electrolyte, effectively reducing the battery's internal resistance at low temperatures and improving its charge / discharge efficiency.

[0031] like Figures 1 to 3 As shown, in some embodiments, the diameter of the first honeycomb hole 11 and the second honeycomb hole 21 is 50-200μm, the hole spacing is 10-50μm, and the first honeycomb hole 11 and the second honeycomb hole 21 are arranged in an alternating structure when the positive electrode current collector 1 and the negative electrode current collector 2 are stacked. The pore size of 50-200μm creates a large number of honeycomb pores on the surface of the positive and negative electrode current collectors 2, which significantly increases the contact area between the electrode and the electrolyte. This means that more active materials can fully contact the electrolyte, thereby accelerating the insertion and extraction process of lithium ions between the electrode and the electrolyte, effectively improving the charging and discharging efficiency of the battery. The pore spacing of 10-50μm ensures that the structural strength of adjacent first honeycomb pores 11 and adjacent second honeycomb pores 21 will not decrease due to being too close, nor will the ion transport efficiency be affected due to being too far apart. The staggered arrangement of the first honeycomb pores 11 and the second honeycomb pores 21 further optimizes the lithium ion transport path. When the positive and negative electrode current collectors 2 are stacked, this staggered arrangement makes the transport of lithium ions between the positive and negative electrodes more uniform, avoiding the problem of excessive or insufficient local current density.

[0032] like Figures 1 to 3 As shown, in some embodiments, the positive electrode active material is NCM811, and the negative electrode active material is a silicon-carbon composite material. NCM811 has a relatively good crystal structure, which is conducive to the insertion and extraction of lithium ions. During charging and discharging, lithium ions can diffuse relatively quickly in the NCM811 lattice, reducing the resistance to ion transport and thus improving the charging and discharging efficiency of the battery. The carbon component in the silicon-carbon composite material not only serves as a supporting framework for silicon but also has good conductivity. During charging and discharging, carbon can quickly conduct electrons, enabling silicon particles to exchange charges with the external circuit in a timely manner. Simultaneously, a reasonable silicon-carbon composite structure design can mitigate the volume change of silicon during charging and discharging, maintain the stability of the electrode structure, and thus improve the battery's fast charging and discharging performance and rate performance.

[0033] like Figure 1 and Figure 4As shown, in some embodiments, a separator 5 is also included, which is wound between the positive current collector 1 and the negative current collector 2. When the battery is in normal use or subjected to external forces such as vibration or compression, the wound separator 5 can reliably separate the positive and negative electrodes, preventing the direct conduction of electrons, thereby preventing serious safety accidents such as battery overheating, fire, or even explosion caused by short circuits, and greatly improving the safety of the battery during use.

[0034] like Figure 1 and Figure 4 As shown, in some embodiments, the separator 5 includes an outer layer 51, a middle layer 52, and an inner layer 53. The outer layer 51 is in contact with the positive electrode current collector 1, and the inner layer 53 is in contact with the negative electrode current collector 2. The outer layer 51 is in contact with the positive electrode current collector 1. During charging and discharging, the positive electrode undergoes a complex redox reaction, generating high potential and heat. The outer layer 51 of the separator 5 can be made of a material with good oxidation resistance and thermal stability, effectively resisting the strong oxidizing environment generated by the positive electrode, preventing side reactions between the positive electrode material and the electrolyte, avoiding dissolution and structural damage of the positive electrode material, thereby improving battery safety and cycle life.

[0035] There is a risk of lithium metal deposition at the negative electrode during charging and discharging, and it may react with the electrolyte to form a solid electrolyte interphase (SEI) film. The inner layer 53 of the separator 5 can be made of a material with good stability to lithium metal, which can inhibit the growth of lithium dendrites, prevent lithium dendrites from piercing the separator 5 and causing a short circuit between the positive and negative electrodes, and reduce the risk of battery thermal runaway.

[0036] The intermediate layer 52 can serve as an additional safety barrier. When the outer layer 51 or the inner layer 53 is slightly damaged due to accidents (such as local overheating, mechanical damage, etc.), the intermediate layer 52 can prevent direct contact between the positive and negative electrodes, further reducing the possibility of short circuits and providing more reliable safety protection for the battery.

[0037] like Figure 1 and Figure 4 As shown, in some embodiments, the outer layer 51 is a polyimide-based film with a thickness of 20-30 μm, coated with an Al2O3 nanoparticle layer; the middle layer 52 is a SiO2 nanowire-reinforced PE separator 5 with a thickness of 15-20 μm; and the inner layer 53 is a PVDF-HFP gel polymer layer with a thickness of 10-15 μm. The polyimide-based film of the outer layer 51 has excellent high-temperature resistance, with high glass transition temperature and thermal decomposition temperature, and can maintain stable physical and chemical properties under high-temperature environments.

[0038] The PVDF-HFP gel polymer layer of the inner layer 53 has good flexibility and stability to lithium metal. It can form a uniform interface layer on the negative electrode surface, inhibiting the growth of lithium dendrites. Even if a small amount of lithium dendrites are generated, the gel polymer layer can buffer the puncture force of lithium dendrites through its own elastic deformation, preventing lithium dendrites from penetrating the separator 5 and causing a short circuit between the positive and negative electrodes, thus ensuring the safe operation of the battery.

[0039] The SiO2 nanowire-reinforced PE separator 5 in the intermediate layer 52 has a unique porous structure and good ion conductivity. The addition of SiO2 nanowires not only enhances the mechanical strength of the separator 5, but also increases the porosity and specific surface area of ​​the separator 5, providing more transport channels for lithium ions. This enables lithium ions to migrate quickly and smoothly between the positive and negative electrodes, improving the charge and discharge efficiency and rate performance of the battery.

[0040] This invention relates to the working principle and process of a wide-temperature-range protective lithium battery. The structure of a positive electrode current collector 1 with first honeycomb pores 11 and a negative electrode current collector 2 with second honeycomb pores 21 provides stable mechanical support and efficient ion and electron transport channels. During charging and discharging, lithium ions in the positive electrode active material migrate directionally to the negative electrode through the positive electrode carbon nanocapsule layer 3 and embed into the negative electrode material coated by the negative electrode carbon nanocapsule layer 4. During discharge, this process is reversed. The low-temperature ionic liquids in the positive and negative electrode carbon nanocapsule layers 3 and 4 remain in a liquid state with high ionic conductivity. At high temperatures, the positive and negative electrode carbon nanocapsule layers 3 and 4 can act as physical barriers, reducing direct contact between the positive and negative electrode active materials and the electrolyte.

[0041] In the description of this utility model, it should be understood that terms such as "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0042] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0043] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0044] Although the description of this utility model has been given in conjunction with the specific embodiments described above, it is obvious to those skilled in the art that many substitutions, modifications, and variations can be made based on the above description. Therefore, all such substitutions, modifications, and variations are included within the spirit and scope of the appended claims.

Claims

1. A wide-temperature-range protected lithium battery, characterized in that, The device includes a positive current collector and a negative current collector. The positive current collector has multiple first honeycomb pores, and the negative current collector has multiple second honeycomb pores. The inner walls of the first honeycomb pores are coated with a positive carbon nanocapsule layer, and the inner walls of the second honeycomb pores are coated with a negative carbon nanocapsule layer. The positive carbon nanocapsule layer contains a positive active material and a low-temperature ionic liquid, and the negative carbon nanocapsule layer contains a negative active material and a low-temperature ionic liquid.

2. The wide-temperature-range protected lithium battery according to claim 1, characterized in that, Both the positive and negative carbon nanocapsule layers have a granular hollow structure at the microscopic level, and the wall thickness of the positive and negative carbon nanocapsule layers is 10-20 nm.

3. The wide-temperature-range protected lithium battery according to claim 1, characterized in that, The low-temperature ionic liquid is [EMIM][TFSI] ionic liquid.

4. The wide-temperature-range protected lithium battery according to claim 1, characterized in that, The diameter of the first and second honeycomb pores is 50-200μm, and the pore spacing is 10-50μm. The first and second honeycomb pores are arranged in an alternating structure when the positive current collector and the negative current collector are superimposed.

5. The wide-temperature-range protected lithium battery according to claim 1, characterized in that, The positive electrode active material is NCM811, and the negative electrode active material is a silicon-carbon composite material.

6. The wide-temperature-range protected lithium battery according to claim 1, characterized in that, It also includes a diaphragm wound between the positive current collector and the negative current collector.

7. The wide-temperature-range protected lithium battery according to claim 6, characterized in that, The diaphragm includes an outer layer, a middle layer, and an inner layer. The outer layer is in contact with the positive current collector, and the inner layer is in contact with the negative current collector.

8. The wide-temperature-range protected lithium battery according to claim 7, characterized in that, The outer layer is a polyimide-based film with a thickness of 20-30 μm, coated with an Al2O nanoparticle layer; the middle layer is a SiO2 nanowire-reinforced PE separator with a thickness of 15-20 μm; and the inner layer is a PVDF-HFP gel polymer layer with a thickness of 10-15 μm.

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