Battery diaphragm and lithium ion battery

Abstract

The utility model provides a battery diaphragm and a lithium ion battery, which relate to the technical field of batteries and comprise a diaphragm base layer and far infrared ceramic coatings arranged on two sides of the diaphragm base layer. The far infrared ceramic coating can effectively absorb and convert heat generated by the pole piece, the heat is reflected back into the battery through radiation, the temperature rise speed of the battery is increased, and especially in a low-temperature environment, the battery can be helped to quickly enter a normal working state. And the far infrared ceramic coating can increase the heat utilization efficiency of the pole piece, reduce the heat waste and effectively promote the heat management of the battery. The method is particularly important for performance optimization of the battery in a cold environment, and the charging and discharging efficiency and the safety of the battery are improved.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to a battery separator and a lithium-ion battery. Background Technology

[0002] With the increasing demand for lithium-ion batteries from electric vehicles, energy storage systems, and portable electronic devices, battery charging performance, lifespan, and safety have become key research areas. Especially in low-temperature environments, the charging efficiency of lithium-ion batteries decreases significantly. In insufficient temperatures, the rate of chemical reactions within the battery slows down, leading to a decline in charging capacity. Therefore, batteries need to be heated before charging.

[0003] Currently, battery heating methods in low-temperature environments mainly include heating with heating elements, liquid cooling plates, and heating via low-current or low-power charging. While these methods can raise battery temperature to some extent, they typically suffer from drawbacks such as slow temperature rise, low energy efficiency, uneven heating, and strong dependence on ambient temperature. Especially when batteries operate in low-temperature environments, the overall temperature rise of the battery pack is often affected by the external ambient temperature, resulting in unsatisfactory temperature rise and ineffective heat retention during charging.

[0004] The battery separator, as a key component inside the battery, primarily functions to isolate the positive and negative electrodes, prevent short circuits, and ensure the normal flow of ions within the battery. However, traditional battery separator materials often exhibit poor thermal insulation performance, which is particularly pronounced in low-temperature environments. Insufficient thermal insulation allows heat to easily escape from the battery's interior, making it difficult to effectively maintain the battery's internal temperature. This results in a slow temperature rise even with external heating methods such as heating elements or liquid cooling systems. Furthermore, during charging, the battery is continuously affected by the ambient temperature, leading to poor overall heating performance.

[0005] Specifically, the high thermal conductivity of the separator material makes it difficult for heat to accumulate effectively inside the battery during heating, thus affecting the uniformity of the battery temperature rise. As the battery temperature increases, the influence of the low temperature of the external environment gradually becomes apparent, weakening the battery heating effect and consequently affecting charging efficiency and battery performance stability. Utility Model Content

[0006] In view of this, the present invention proposes a battery separator and a lithium-ion battery, which can reduce heat loss during the low-current heating process of the battery in low-temperature environments and improve the self-heating capacity or heat preservation capacity of the lithium-ion battery.

[0007] The technical solution of this utility model is implemented as follows:

[0008] In a first aspect, the present invention provides a battery separator, including a separator base layer and a far-infrared ceramic coating disposed on both sides of the separator base layer.

[0009] Based on the above technical solution, preferably, the far-infrared ceramic coating is composed of at least one ceramic material, which is selected from one or more of alumina, titanium oxide, silicon nitride, and zircon.

[0010] Based on the above technical solution, preferably, the far-infrared ceramic coating has an emissivity greater than 0.8 in the far-infrared band of 8 to 14 micrometers.

[0011] Based on the above technical solution, preferably, the thermal reflectivity of the far-infrared ceramic coating is greater than 80%.

[0012] Based on the above technical solution, preferably, the surface smoothness of the far-infrared ceramic coating is Ra≤0.5μm.

[0013] Based on the above technical solution, preferably, both the diaphragm base layer and the far-infrared ceramic coating have a microporous structure, with the porosity of the diaphragm base layer being 30%-60% and the porosity of the far-infrared ceramic coating being 5%-40%.

[0014] Based on the above technical solution, preferably, the thickness of the diaphragm base layer is 1μm-25μm, and the thickness of the far-infrared ceramic coating is 0.5μm-10μm.

[0015] Based on the above technical solution, preferably, the thermal conductivity of the diaphragm base layer is in the range of 0.1 W / m·K to 0.3 W / m·K.

[0016] Based on the above technical solution, preferably, the far-infrared ceramic coating is applied to the surface of the diaphragm base layer by spraying, sputtering, dipping, or chemical vapor deposition.

[0017] Secondly, this utility model provides a lithium-ion battery for use in low-temperature environments, including the battery separator described in the first aspect.

[0018] The present invention has the following advantages over the prior art:

[0019] (1) The far-infrared ceramic coating can effectively absorb and convert the heat generated by the electrode, reflecting the heat back into the battery through radiation, thereby enhancing the battery's temperature rise rate. Especially in low-temperature environments, it can help the battery quickly enter normal operating conditions. The far-infrared ceramic coating can increase the heat utilization efficiency of the electrode, reduce heat waste, and effectively promote battery thermal management. This is particularly important for optimizing battery performance in cold environments, improving battery charging and discharging efficiency and safety.

[0020] (2) By setting a far-infrared ceramic coating, the emissivity of the coating is made greater than 0.8 in the far-infrared band of 8 to 14 micrometers. The coating with an emissivity greater than 0.8 has a strong heat radiation capability, especially in the far-infrared band of 8 to 14 micrometers. The high emissivity of the coating enables it to efficiently absorb and radiate heat, thereby accelerating the temperature rise of the battery. Especially in low-temperature environments, it can significantly improve the temperature rise efficiency of the battery, optimize low-temperature charging performance, and avoid performance degradation and safety hazards caused by excessively low temperatures.

[0021] (3) By setting the thermal reflectivity of the far-infrared ceramic coating to be greater than 80%. A coating with a thermal reflectivity greater than 80% can effectively reflect the heat generated by the electrode and reflect it back into the battery, thereby accelerating the temperature rise of the battery. Combined with the characteristics of far-infrared radiation, this high-reflectivity coating can ensure that the heat does not spread rapidly to the outside of the battery, but is reflected and retained inside the battery, thus rapidly increasing the temperature of the battery.

[0022] (4) By setting a lower porosity for the far-infrared ceramic coating, the density of the coating can be increased, the thermal reflectivity of the coating can be improved, and it can reflect heat more effectively. Lower porosity helps to reduce the thermal conductivity of the coating. Ceramic materials themselves have strong thermal conductivity. By controlling the porosity, the thermal conductivity of the ceramic coating can be adjusted, and its thermal insulation performance can be enhanced.

[0023] (5) By setting the separator base layer to have low thermal conductivity, the diffusion and loss of heat inside the battery are reduced, thereby maintaining heat accumulation inside the battery. Especially in low-temperature environments, this reduces the impact of external low temperatures and optimizes the heating effect. Low thermal conductivity helps the separator to play a thermal isolation role when the battery is working, keeping the battery temperature stable and preventing excessive heat loss. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a planar schematic diagram of the battery separator disclosed in this utility model;

[0026] Figure 2 This is a schematic diagram of the battery separator and electrode assembly structure disclosed in this utility model;

[0027] Figure label:

[0028] 1. Diaphragm base layer; 2. Far-infrared ceramic coating; 3. Electrode. Detailed Implementation

[0029] The technical solutions of this utility model will be clearly and completely described below with reference to the embodiments of this utility model. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this utility model.

[0030] like Figure 1 and 2 As shown, this utility model discloses a battery separator, including a separator base layer 1 and far-infrared ceramic coatings 2 disposed on both sides of the separator base layer. In this embodiment, the separator base layer 1 is used to ensure the smooth flow of ion channels inside the battery and prevent short circuits in the positive and negative electrodes of the battery. The far-infrared ceramic coating is mainly used for the thermal management of the battery.

[0031] Inside the battery, a battery separator is placed between the positive and negative electrodes. The far-infrared ceramic coating 2 contacts the electrodes. When the battery is charged with a small current at low temperatures, the electrodes generate heat through the current. Due to heat diffusion within the battery, the heat gradually diffuses to the surrounding areas, resulting in a slow temperature rise. In this example, the battery separator surface is coated with a far-infrared ceramic coating 2. This coating absorbs heat loss from the electrodes and, as its own temperature rises, converts the heat into far-infrared radiation, which is then reflected back to the electrodes, increasing the heat utilization efficiency of the electrodes and causing the battery temperature to rise rapidly.

[0032] The far-infrared ceramic coating 2 effectively absorbs and converts the heat generated by the electrodes, reflecting it back into the battery through radiation. This enhances the battery's temperature rise rate, especially in low-temperature environments, helping the battery quickly reach normal operating conditions. The far-infrared ceramic coating 2 also increases the electrode's heat utilization efficiency, reducing heat waste and effectively promoting battery thermal management. This is particularly important for optimizing battery performance in cold environments, improving charging and discharging efficiency and safety.

[0033] As some preferred embodiments, the far-infrared ceramic coating 2 is composed of at least one ceramic material selected from one or more of alumina, titanium oxide, silicon nitride, and zircon.

[0034] Ceramic materials such as alumina (Al2O3), titanium dioxide (TiO2), silicon nitride (Si3N4), and zircon (ZrO2) typically have high emissivity in the far-infrared band, enabling them to effectively absorb and reflect heat. These properties allow the coating to convert external heat into far-infrared radiation and reflect it back to the battery electrodes, thereby increasing the battery temperature.

[0035] In this embodiment, the far-infrared ceramic coating 2 has an emissivity greater than 0.8 in the far-infrared band of 8 to 14 micrometers. A coating with an emissivity greater than 0.8 exhibits strong heat radiation capability, particularly in the 8 to 14 micrometer far-infrared band. This high emissivity allows the coating to efficiently absorb and radiate heat, thereby accelerating the temperature rise of the battery. Especially in low-temperature environments, this significantly improves the battery's temperature rise efficiency, optimizes low-temperature charging performance, and avoids performance degradation and safety hazards caused by excessively low temperatures.

[0036] As one preferred embodiment, the far-infrared ceramic coating 2 has a thermal reflectivity greater than 80%. A coating with a thermal reflectivity greater than 80% can effectively reflect the heat generated by the electrodes back into the battery, thereby accelerating the battery's temperature rise. Combined with the characteristics of far-infrared radiation, this high-reflectivity coating ensures that heat does not rapidly diffuse to the outside of the battery, but is reflected and retained inside, quickly increasing the battery's temperature.

[0037] In some preferred embodiments, the surface smoothness of the far-infrared ceramic coating 2 is Ra≤0.5μm. Surface smoothness has a significant impact on the adhesion, uniformity, and thermal conductivity of the coating. Higher surface smoothness (Ra≤0.5μm) allows the coating to be applied more uniformly to the surface of the diaphragm base layer 1, reducing surface irregularities and thus improving the coating's heat reflection and radiation capabilities.

[0038] In some preferred embodiments, both the diaphragm base layer 1 and the far-infrared ceramic coating 2 have microporous structures, with the porosity of the diaphragm base layer 1 being 30%-60% and the porosity of the far-infrared ceramic coating 2 being 5%-40%.

[0039] A membrane substrate with high porosity 1 facilitates the permeation of electrolyte within the membrane, thereby promoting the migration of lithium ions through the membrane during battery charging and discharging. A porosity of 30%-60% provides sufficient channels for electrolyte permeation and helps lithium ions flow freely during charging and discharging.

[0040] The primary function of the far-infrared ceramic coating 2 is to regulate battery temperature by reflecting and radiating heat. Appropriate porosity helps improve the reflectivity and emissivity of the ceramic coating. Lower porosity (e.g., 5%-40%) increases the coating's density, improves its thermal reflectivity, and makes it more effective at reflecting heat. Lower porosity also helps reduce the coating's thermal conductivity. Ceramic materials themselves have high thermal conductivity; by controlling porosity, the thermal conductivity of the ceramic coating can be adjusted, enhancing its thermal insulation performance. Furthermore, the low porosity of the far-infrared ceramic coating 2 helps improve its surface smoothness and reduce surface roughness, enhancing the coating's mechanical properties and adhesion to the base film.

[0041] In this embodiment, the thickness of the separator base layer 1 is 1μm-25μm, and the thickness of the far-infrared ceramic coating 2 is 0.5μm-10μm. The separator base layer 1 is an important component of the battery's internal structure, serving to support the electrodes and provide insulation. It is typically made of polymer materials (such as polyethylene or polypropylene), possessing mechanical strength and flexibility. Because it is responsible for providing mechanical support, ion conduction, and electrolyte permeation, a certain thickness is required to meet these requirements. The far-infrared ceramic coating 2 has a smaller thickness because its main function is heat reflection and radiation, and this thermal management function does not depend on thickness; only a sufficiently thin coating is needed for efficient heat reflection.

[0042] In this embodiment, the thermal conductivity of the separator base layer 1 ranges from 0.1 W / m·K to 0.3 W / m·K. The separator base layer 1 mainly functions to conduct electrolyte ions, isolate the positive and negative electrodes, and provide structural support. The purpose of setting it to have low thermal conductivity is to reduce heat diffusion and loss within the battery, thereby maintaining heat accumulation inside the battery, especially in low-temperature environments, reducing the impact of external low temperatures, and optimizing heating performance. Low thermal conductivity helps the separator to provide thermal insulation during battery operation, maintaining stable battery temperature and preventing excessive heat loss.

[0043] It is worth noting that the far-infrared ceramic coating 2 is typically not characterized by low thermal conductivity; rather, its reflectivity and radiation properties are more important. Far-infrared ceramic materials themselves often possess high thermal reflectivity and good thermal radiation performance, but their thermal conductivity is relatively high. This is because ceramic materials generally have good thermal conductivity; their role is not as a heat insulation material, but rather to improve the battery's thermal management efficiency through heat radiation and reflection. Therefore, the far-infrared ceramic coating 2 does not need to have low thermal conductivity; its key function lies in thermal radiation and thermal reflection.

[0044] As some implementation methods, the far-infrared ceramic coating 2 is applied to the surface of the separator substrate 1 through spraying, sputtering, dip coating, or chemical vapor deposition. The process can be flexibly selected during the preparation of the ceramic coating to optimize adhesion, control coating thickness, improve thermal performance, ensure coating uniformity, and enhance coating stability. Appropriate selection of the coating process can ensure the effective application of the ceramic coating on the separator substrate 1, thereby improving overall battery performance, extending service life, and optimizing the battery's thermal management performance.

[0045] This utility model also discloses a lithium-ion battery for use in low-temperature environments, comprising the aforementioned battery separator. By using a battery separator with a far-infrared ceramic coating 2 in the lithium-ion battery, the heat reflection and heat radiation properties of the far-infrared ceramic coating 2 can help the battery maintain thermal balance under low-temperature conditions, slow down the drop in internal battery temperature, and improve the battery's charge and discharge performance in low-temperature environments.

[0046] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A battery separator, characterized in that: It includes a diaphragm base layer (1) and far-infrared ceramic coatings (2) disposed on both sides of the diaphragm base layer (1); the far-infrared ceramic coating (2) has an emissivity greater than 0.8 in the far-infrared band of 8 to 14 micrometers; the thermal reflectivity of the far-infrared ceramic coating (2) is greater than 80%.

2. The battery separator as described in claim 1, characterized in that: The surface smoothness of the far-infrared ceramic coating (2) is Ra≤0.5μm.

3. The battery separator as described in claim 1, characterized in that: Both the diaphragm base layer (1) and the far-infrared ceramic coating (2) have microporous structures. The porosity of the diaphragm base layer (1) is 30%-60%, and the porosity of the far-infrared ceramic coating (2) is 5%-40%.

4. The battery separator as described in claim 1, characterized in that: The thickness of the diaphragm base layer (1) is 1μm-25μm, and the thickness of the far-infrared ceramic coating (2) is 0.5μm-10μm.

5. The battery separator as described in claim 1, characterized in that: The thermal conductivity of the membrane base layer (1) ranges from 0.1 W / m•K to 0.3 W / m•K.

6. The battery separator as described in claim 1, characterized in that: The far-infrared ceramic coating (2) is applied to the surface of the diaphragm base layer (1) by spraying, sputtering, dipping, or chemical vapor deposition.

7. A lithium-ion battery for use in low-temperature environments, characterized in that, Includes the battery separator as described in any one of claims 1 to 6.

Images