Lithium iron phosphate water-based positive electrode slurry, preparation method thereof and environment-friendly long-circulation lithium ion battery

Abstract

The invention provides a lithium iron phosphate water-based positive electrode slurry, a preparation method thereof and an environment-friendly long-circulation type lithium ion battery. Solid powder lithium iron phosphate, CMC and conductive carbon black are firstly subjected to dry mixing, then deionized water, EC and a PAA solution are added, kneading is performed, then deionized water and CNTs are added, high-rotating-speed dispersion is performed, after the dispersion is finished, an SBR emulsion is added, and mixing is performed to obtain uniform and stable water-based positive electrode slurry; and the water-based positive electrode slurry can be used for preparing the environment-friendly long-circulation type lithium ion battery through the effects of coating and the like. According to the invention, deionized water is adopted as the solvent of the positive electrode slurry, so that the solvent is environment-friendly, secondary recovery is not needed, the source is rich, and the preparation cost is low; and the 25 DEG C cycle performance of a prepared water-based lithium iron phosphate battery cell is as follows: the capacity retention rate reaches about 95% after 1000 cycles. Moreover, the lithium ion battery provided by the invention is good in processing stability.

Description

technical field [0001] The invention belongs to the field of batteries, and in particular relates to a lithium iron phosphate aqueous cathode slurry, a preparation method thereof, and an environment-friendly long-cycle lithium ion battery. Background technique [0002] With the continuous development of lithium-ion batteries, the demand for lithium-ion battery-related products is increasing day by day. Nowadays, NMP is still used as a solvent for the preparation of positive electrode slurry for lithium-ion batteries. This solvent needs to be recycled twice during the production process. One is that the recovery is not thorough and volatile, which causes environmental pollution; the other is that there is energy consumption in the recovery process, which increases costs; and the third is that NMP needs to be purchased additionally as an industrial solvent, which increases costs. [0003] The Chinese invention patent application published on January 20, 2016 with the publicati...

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Problems solved by technology

[0002] With the continuous development of lithium-ion batteries, the demand for lithium-ion battery-related products is increasing day by day. Nowadays, NMP is still used as a solvent for the preparation of positive electrode slurry for lithium-ion batteries. This solvent needs to be recycled twice during the production process. One is that the recovery is not thorough and volatile, resulting in environmental pollution; the other is that there is energy consumption in the recycling process, which increases costs; and the third is that NMP needs to be purchased additionally as an industrial solvent, which increases costs

[0003] The Chinese invention patent application published on January 20, 2016 with the publication number CN105261760A discloses a lithium-ion battery aqueous positive electrode composite current collector, a positive electrode sheet and its preparation method, and a lithium-ion battery, and shows that the prepared battery has improved cycle performance. However, the actual battery cell cycle capacity retention rate of 500 cycles is lower than 90%, which cannot meet the demand for the existing long-cycle lithium iron phosphate battery

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