Patent Application
20200067102
The invention relates to a structure of an electrochemical energy storage device, particularly to an electrode structure of an electrochemical energy storage device and manufacturing method thereof.
Recently, electrochemical energy storage devices (EESDs), such as lithium-ion batteries (LIBs), lithium-sulfur (Li—S) batteries and super capacitors (SCs), have been widely applied to electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), wireless electrical tools, wireless power supplies and other electricity storage systems. EESDs have made significant progress by research and improvement in recent years, but their energy density, power density and service life are still hard to satisfy actual requirements. With rapid development of wearable electronic devices, a new EESD with compactness, lightweight and high energy density is urgently required.
A lithium-ion battery is composed of a positive electrode, a negative electrode, an electrolyte and an isolation film. Usually, the electrode includes two portions, an electrode material and a current collector. The two electrodes are the constituent components of a lithium-ion battery cell. In such a battery, lithium ions move from the negative electrode to the positive electrode during discharge and back when charging. The current collector is an elementary accessory for finishing a current loop. The electrolyte, which allows for ionic movement, significantly affects the performance of the battery system because it must have a wide electrochemical window, great chemical stability and high ion conductance.
The electrochemical reaction therein is a chemical change which occurs when electrons pass the metal-electrolyte interface. When the electrolyte is embedded into the electrode material, the power density of a lithium-ion battery will be electrochemically reduced. During this period, the coulombic efficiency attitudes simultaneously. In addition, increase of obstruction is usually accompanied by heat. According to the principle of electrochemical reaction, the interface between the electrodes and electrolyte needs to be enhanced to reduce undesired electrochemical reaction and to improve efficiency.
Energy density of a lithium-ion battery primarily depends upon its output voltage and specific capacity, and the magnitude of the voltage and specific capacity is decided by electrochemical performance. Electrode material has been developed in depth.
US patent publication No. 2004/0191632 provides a battery including carbon foam current collectors. The carbon foam current collector that has a network of pores can provide a large amount of surface area. Such an improvement will affect energy density, power density and service life of a lead-acid battery. This current collector includes a network of pores and a chemically active paste disposed on the carbon foam current collector such that the chemically active paste penetrates into the network of pores.
US patent publication No. 2013/0065122 provides a semi-solid electrode cell having a porous current collector and method of manufacture. Its porous current collector may form a metal mesh and may be made of any proper metal or non-metal material. The porous current collector enhances energy density and power density of an electrochemical battery.
US patent publication No. 2013/0252091 provides a lithium ion battery electrode which has an electro-conductive current collector with porous three-dimensional network construction. Such a current collector improves the electrode active material utilization and the electrode processability.
US patent publication No. 2011/0070489 provides a reticulated and controlled porosity battery structure which has a mesh component or a component with a mesh interface so as to increase the interface area. The added interface perimeter increases usable positions of ion matter reaction. The quantity of the reaction positions allows ion matter to diffuse to the surface. The electrolyte is solid and the ion matter is Li+.
US patent publication No. 2014/0186700 provides an advanced, high power and energy battery electrode manufactured by co-extrusion printing, which has a cathode material forming a pore channel. Such a pore channel promotes actions of sink or source of lithium ion movement. When lithium ions pass the pore channels from another material, the pore channels form shorter and straighter path channels. This allows to use a thicker electrode so that the cathode possesses high power and energy density in volume.
The technical problem which is solved by the invention is to provide an electrode structure of electrochemical energy storage device and manufacturing method thereof.
To solve the above technical problem, an embodiment of the electrode structure of electrochemical energy storage device of the invention includes: a current collector; an electrode material, coated on the current collector, and being an electroactive material; and at least one through hole penetrating through the electrode material and the current collector.
In a preferred embodiment, the invention includes multiple through holes.
The method for manufacturing an electrode structure of electrochemical energy storage device includes: a) preparing a current collector; b) coating a surface of the current collector with an electrode material which is an electroactive material; and c) forming at least one through hole penetrating through the electrode material and the current collector.
The current collector is made of a metal or non-metal material.
The electroactive material includes lithium or anyone of an alloy containing lithium, a graphite-like material, a metal oxide, a sulfide and a nitride.
Advantages of the invention includes:
1) decreasing weigh proportion of the current collector;
2) increasing fluid retention of the electrolyte to extend the cycle life;
3) enhancing adhesion between the electroactive material and the current collector;
4) raising flexibility of the current collector; and
5) improving the moving ability of ions of electrolyte in an electrochemical energy storage device in all directions, wherein increase of both moving efficiency of ions in electrolyte and selectable paths of moving ions can raise charging and discharging efficiency at different charging and discharging speed.
Also, by the through hole and the electrode material coated on the current collector, the reaction with electrolyte ions can be improved during high current density charging and discharging to obtain a high power density.
The positional relationship in the following description, including top (upper), bottom (lower), left and right, is based on the directions in the drawings if no special indication.
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The EESD may be applied to, for example, an electrochemical cell, an electrochemical capacitor, lithium-ion battery and lithium-ion capacitor. Furthermore, the electrode structure of the EESD of the invention is suitable for electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), wireless electrical tools, wireless power supplies and other electricity storage system.
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A preferred embodiment of step b) is to prepare a pulp of the electrode material 20 first, then evenly daub the pulp onto the current collector 10, and finally form an even coating layer on the current collector 10 by a drying treatment. A preferred embodiment of step c) is to perform a punching process to form the through hole 30.
Another embodiment of the method of the invention is to form the through hole 30 in the current collector 10 first, and then coat the current collector 10 having the through hole 30 with the electrode material 20.
The current collector 10 is made of a metal or non-metal material and may be a foil or mesh. The electroactive material includes lithium or anyone of an alloy containing lithium, a graphite-like material, a metal oxide, a sulfide and a nitride. For example, an anode material of a lithium battery is LiMn2O4, LiFePO4 or LiNiCoO2, and its cathode material is usually a carbon material including graphite and coke. By the through hole 30 and the electrode material 20 coated on the current collector 10, the reaction with electrolyte ions can be improved during high current density charging and discharging to obtain a high power density.
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By the arrangement of the through hole 30, the invention has advantages as follows:
1) decrease weigh proportion of the current collector 10;
2) increase fluid retention of the electrolyte to extend the cycle life;
3) enhance adhesion between the electroactive material and the current collector 10;
4) raise flexibility of the current collector 10; and
5) improve the moving ability of ions of electrolyte in an electrochemical energy storage device in all directions, wherein increase of both moving efficiency of ions in electrolyte and selectable paths of moving ions can raise charging and discharging efficiency at different charging and discharging speed. Also, by the through hole 30 and the electrode material 20 coated on the current collector 10, the reaction with electrolyte ions can be improved during high current density charging and discharging to obtain a high power density.
Those skilled in the art will appreciate that numerous changes and modifications can be made to the preferred embodiments of the invention, and that such changes and modifications can be made without departing from the spirit of the invention.
