Cathode material of lithium ion battery, preparation method of cathode, and lithium ion battery

Abstract

The invention discloses a cathode material of a lithium ion battery, a preparation method of the cathode, and the lithium ion battery using the cathode material, belonging to the technical field of energy material. According to the invention, a chemical dispersant is added into the cathode of an aqueous lithium-ion battery, thereby solving problems of uniform dispersion for active materials of positive electrode and a nano-carbon mixed conductive agent; and a mechanical dispersion method is combined, preferably with a revolution speed of the mechanical dispersion being 15-35 HZ and a rotation speed being 10-30 HZ, thereby realizing uniform dispersion of the nano-active substances in a relatively short time. The cathode material of a lithium ion battery and the preparation method provide technical approach for solving uniform dispersion of the aqueous nano-active substances, and are high in production efficiency and low in cost; the prepared battery is high in discharge capacity, and is significantly improved in low temperature, multiplying power and cycling performances; and a new approach is provided for a large scale application of the nanometer lithium batteries which are limited to a high cost and a high-polluting oil system in the field.

Description

technical field [0001] The invention relates to a lithium ion secondary battery, in particular to a lithium ion battery positive electrode material, a preparation method for the positive electrode, and a lithium ion battery using the positive electrode material, belonging to the technical field of energy materials. Background technique [0002] As a new type of recyclable green energy, lithium-ion secondary batteries have the advantages of high working voltage, high specific energy, long cycle life, wide working range, good safety performance, and no memory effect. Products, electric vehicles, power supply systems for national defense and military equipment, as well as photovoltaic energy storage, energy storage peak-shaving power stations, uninterruptible power supplies and many other fields have broad application prospects. [0003] At present, lithium cobalt oxide is the main anode of commercial lithium batteries, but its synthesis method is expensive, pollutes the enviro...

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Problems solved by technology

[0005] However, after the nanometerization of lithium iron phosphate materials, due to the reduced particle size and high surface energy, the nanoparticles are prone to agglomeration in the dispersion medium, especially in the water system, and the key processes such as slurry mixing and coating are very difficult. Phosphoric acid The performance of lithium iron materials is difficult to play, which greatly limits the large-scale application of nano-lithium iron phosphate cathode materials

Chinese patent (Notice No.: CN101950805A) discloses a method for mixing nano-lithium iron phosphate materials. Firstly, the materials are mixed and stirred by a planetary mixer at normal pressure, and then the pipeline emulsifier is used to make the slurry pass through, and finally the planetary mixer is used. Type agitator for the second normal pressure agitation to achieve uniform dispersion of nano-lithium iron phosphate. This method has cumbersome steps and low production efficiency

Chinese patent (notification number: CN101937990A) adopts the method of mechanical stirring to prepare an oil-based nano-lithium iron phosphate slurry, but the mechanical dispersion equipment in this method is expensive, and only in a certain area the energy is high enough to achieve uniformity of nanoparticles Dispersion, and the slurry is easy to settle after standing, and the shear rate will cause damage to the material if the shear rate reaches a certain limit, resulting in particle breakage and affecting the performance of the battery

Chinese patent (publication number: CN102376980A) discloses a method for preparing an oil-based carbon-free lithium iron phosphate battery. Active materials such as lithium iron phosphate are mechanically ground to below 5 microns. The equipment required by this method is expensive and easy to use. The environment is polluted, and the electrochemical performance of nano-scale carbon-free lithium iron phosphate obtained after post-processing is much lower than that of the carbon-coated nano-lithium iron phosphate that has been commercialized at present, and the production cost is high

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