Interface modification method of lithium battery composite single crystal positive electrode material

Abstract

The invention discloses an interface modification method of a lithium battery composite single crystal positive electrode material. The method comprises the following steps: 1) preparing an acrylonitrile monomer solution, adding a photoinitiator into the acrylonitrile monomer solution, atomizing the monomer solution, spraying the atomized monomer solution on the surface of the single crystal positive electrode material, and placing the treated positive electrode material in a mechanical fusion machine for fusion; 2) in a mechanical fusion machine, carrying out the polymerization reaction on the fused material under the irradiation of an ultraviolet lamp, and uniformly coating the surface of the positive electrode material with an ionic liquid monomer; 3) after the polymerization reaction is finished, placing the polymer-coated positive electrode material in a tubular furnace, and carrying out heat treatment at 150-300 DEG C to obtain the composite single crystal positive electrode material with the modified interface. After interface modification, the surface of the single crystal positive electrode is uniformly coated with the polymer, so that the contact area of the battery positive electrode material and the electrolyte can be reduced, side reaction and corrosion are avoided, the cycle life of the single crystal positive electrode material is prolonged, the rate capability of the single crystal positive electrode material is improved, and the single crystal ternary positive electrode material with excellent comprehensive performance for the lithium battery is obtained.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to an interface-modified single-crystal particle positive electrode material and a preparation method thereof. Background technique: [0002] Lithium-ion batteries have outstanding advantages such as high working voltage, high energy density, large specific capacity, small self-discharge, and long service life, and gradually become the ideal power supply for mobile phones, computers, other consumer electronics products, and even automobiles. From 1991 to today, lithium-ion batteries have entered every household. With the continuous occurrence of lithium-ion battery combustion and even explosion accidents, higher requirements are gradually put forward for the safety performance of lithium-ion batteries; In pursuit of volumetric energy density in a limited space, researchers have turned their attention to single crystal cathode materials with higher tap density (primary ...

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Problems solved by technology

However, this method first needs to modify the surface of the ternary cathode material to introduce active groups, which will have a certain adverse effect or even damage the structure of the secondary particles, which is not conducive to the improvement of battery performance.

[0005] There is also the use of polymer materials to modify the interface of the positive electrode material, such as CN105702919A, which is to wrap the surface of the lithium-ion battery electrode with the interface-stabilized polymer material polyvinylene carbonate (PVCA), but this method is to make the monomer After polymerizing, the polymer material is dissolved in an organic solvent as a binder to modify the surface of the positive electrode material. It is not an in-situ polymerization growth method. The polymer modified material is unevenly distributed on the positive electrode material, and general interface modification cannot be avoided. poor consistency defect

CN109273674A discloses a method for modifying the interface of a ternary positive electrode material by acrylic acid polymerization, which is to dissolve polyacrylic acid in a solvent and disperse evenly, then add the ternary positive electrode material dropwise, heat to remove the solvent, and obtain polyacrylic acid after neutralization with LiOH Lithium-coated ternary cathode materials, which also polymerize the modified monomer first and then coat with the cathode material, also have the problem of poor consistency

Moreover, if the method of in-situ polymerization in solution is used, even after the positive electrode material is modified by using a silane coupling agent, the coating of the polymer is not uniform, and it is impossible to obtain a surface modified material with a good consistency of the polymer wrapped positive electrode. The addition of a silane coupling agent will adversely affect the electrochemical performance of the cathode material

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