Lithium ion capacitor

Abstract

The invention provides a lithium ion capacitor. The lithium ion capacitor comprises electrolyte and a core. The core comprises a positive pole, a negative pole and a diaphragm, wherein the positive pole comprises a positive pole current collector and a positive pole coating layer; the negative pole comprises a negative pole current collector and a negative pole coating layer which contains substances being capable of realizing reversible doping of lithium ions and is arranged opposite to the positive pole coating layer; and the diaphragm is arranged between the positive pole and the negative pole. The positive pole current collector comprises a first metal area which is formed in the vicinity of the edge of the positive pole current collector and not coated with the positive pole coating layer; the negative pole current collector comprises a second metal area which is formed in the vicinity of the edge of the negative pole current collector and not coated with the negative pole coating layer; in the core, the area of the negative pole coating layer is larger than that of the positive pole coating layer, the area of the negative pole coating layer can cover the area of the positivepole coating layer, and the negative pole coating layer can enable the positive pole coating layer to be included on the inner side of the negative pole coating layer; and in the core, the area of the diaphragm is larger than that of the negative pole coating layer, and the area of the diaphragm can cover the area of the negative pole coating layer.

Description

technical field [0001] The invention relates to an energy storage device, in particular to a lithium ion capacitor. Background technique [0002] With the development of new energy technology, lithium-ion secondary battery is a new type of energy storage device, because of its high energy density, long cycle life, energy saving and environmental protection, etc. The field has been more and more widely used; but because the performance of the lithium-ion secondary battery itself determines its high-current charge and discharge performance and relatively poor safety performance, it also limits its application in solar energy, wind energy, power vehicles, electric vehicles, etc. field applications. [0003] As another new type of energy storage device, supercapacitors have been widely used in many fields because of their high power density, high electrostatic capacity and longer cycle life than lithium-ion secondary batteries. It has the advantages of high power density, fast...

AI Technical Summary

Problems solved by technology

[0002] With the development of new energy technology, lithium-ion secondary batteries are used as a new type of energy storage device. Because of their advantages such as high energy density, long cycle life, energy saving and environmental protection, they are widely used in mobile phones, notebook computers, digital cameras, etc. The field has been more and more widely used; but because the performance of the lithium-ion secondary battery itself determines its high-current charge and discharge performance and relatively poor safety performance, it also limits its application in solar energy, wind energy, power vehicles, electric vehicles, etc. field application

[0003] As another new type of energy storage device, supercapacitors have been widely used in many fields because of their high power density, high electrostatic capacity and longer cycle life than lithium-ion secondary batteries. It has the advantages of high power density, fast charge and discharge speed, and long cycle life, and is expected to be more widely used in new energy vehicles, solar energy, wind energy and other fields; but due to its low energy density, it is difficult to perform continuous discharge. Therefore, Limits the application of supercapacitors

[0004] Due to the technical defects that are difficult to overcome in the above-mentioned energy storage devices, people hope that a new type of energy storage device can combine the advantages of lithium-ion secondary batteries and supercapacitors to overcome their respective technical defects; thus, people A new type of energy storage component has been developed. The energy storage component connects the lithium-ion secondary battery cell and the supercapacitor, and then manages it through the power management system, which makes the lithium-ion secondary battery and supercapacitor The advantages of capacitors are effectively brought into play, but their manufacturing costs are high, and they do not fundamentally solve the technical defects of lithium-ion secondary batteries and supercapacitors

[0005] In order to fundamentally solve the technical defects of lithium-ion secondary batteries and supercapacitors, and to make better use of the advantages of the two, people have developed lithium-ion capacitors. The negative electrodes of lithium-ion capacitors generally use carbon materials. , the positive electrode uses activated carbon. In order to increase the energy density of lithium ion capacitors, the carbon material of the negative electrode is usually doped with lithium ions or adsorbed lithium ions by electrochemical methods, so that the potential of the negative electrode decreases. Because the potential of the negative electrode that absorbs lithium ions is lower than The activated carbon used in the positive electrode, therefore, the voltage resistance of the capacitor formed by combining it with the positive activated carbon is improved, and the capacity of the negative electrode is much larger than that of the positive electrode, and the energy density of the lithium-ion capacitor is improved; although the lithium-ion capacitor is effectively combined The advantages of lithium-ion secondary batteries and supercapacitors, high energy density, high output characteristics and other advantages, but found in the process of use, its equivalent series internal resistance is large, and in the process of repeated charging and discharging of lithium-ion capacitors , lithium ions are easily precipitated on the surface of the positive electrode, and then form dendrites, resulting in an internal short circuit of the lithium ion capacitor

[0006] For this reason, Chinese invention patent application publication CN101253588A published on August 27, 2008 discloses a lithium ion capacitor. However, it is found in practice that since the positive and negative coating layers cover the entire current collector, when welding the positive and negative terminals on the current collector, it is usually necessary to scrape off part of the coating Therefore, the processing technology is complex and the manufacturing cost is high; and the positive and negative terminals of lithium ion capacitors with this structure are usually welded by ultrasonic welding at several points. Since the points are mostly arranged in a straight line, Moreover, the internal resistance of the contact with the positive and negative electrodes is relatively large, which reduces the energy density of the lithium-ion capacitor and increases the calorific value during use, thereby reducing the overall life of the lithium-ion capacitor

[0007] Therefore, it is necessary to improve the structure of lithium ion capacitors based on the complex processing technology, large internal resistance, lithium ion capacitor positive electrode surface, lithium ion capacitor internal short circuit and many other problems in traditional technology lithium ion capacitors.

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