Lithium ion battery and preparation method thereof

Abstract

The invention provides a lithium ion battery. The lithium ion battery is characterized in that a current collector of a positive plate of the lithium ion battery is coated with a paste layer, and the paste layer comprises lithium iron phosphate, carbon nanotubes, organolithium and PVDF (polyvinylidene fluoride). The invention further provides a preparation method of the lithium ion battery. The preparation method comprises the following steps that lithium iron phosphate, the carbon nanotubes, organolithium and PVDF are weighed in mass ratio, and NMP (N-methylpyrolidone) is weighed quantitatively; part of NMP is taken out, PVDF is dissolved in the part of NMP, and a glue solution is prepared; the carbon nanotubes and organolithium are added to residual NMP, the mixture is subjected to high-speed dispersion and then subjected to ultrasonic dispersion, lithium iron phosphate is added, the mixture is subjected to second high-speed dispersion, and dispersed paste is prepared; the glue solution is added to the dispersed paste for high-speed mixed dispersion, and positive electrode paste is prepared; the current collector is coated with the positive electrode paste, and the positive plate is prepared; the battery is prepared through assembly. The lithium ion battery has the advantages that exertion of capacity density of the positive electrode is integrated while the electrical conductivity of the battery is improved, the capacity of the lithium ion battery is increased, and the rate capability and the cycle performance of the lithium ion battery are enhanced.

Description

technical field [0001] The invention belongs to the field of lithium ion batteries, in particular to a lithium ion battery and a preparation method thereof. Background technique [0002] As a new generation of green energy, power lithium-ion batteries are widely used in electric vehicles and commercial vehicles, and have won unanimous praise from customers and are becoming more and more popular among customers. Fast charging, long battery life, and long life are undoubtedly the future development direction of electric vehicles. This requires power ion batteries to have excellent rate performance and cycle performance, while having higher energy density. As a lithium-ion power battery material, lithium iron phosphate has the advantages of non-toxicity, pollution-free, good safety performance, wide source of raw materials, cheap price, etc., which is unmatched by other materials. However, in lithium-ion batteries using lithium iron phosphate as raw material, lithium iron pho...

AI Technical Summary

Problems solved by technology

The current conductive agents mainly include SP (carbon black conductive agent) and KS-6 (graphite conductive agent) compound. SP and KS-6 have general conductivity and poor conductivity compared with carbon nanotubes, which affects the rate performance of the battery. Moreover, the proportion of conductive agent is too large, which affects the proportion of active material in the electrode sheet, thereby affecting the capacity increase; SP is a small particle size conductive agent, which hinders mass transfer, affects the effective use of positive electrode capacity, and ultimately affects the lithium ion capacity. The energy density of the battery is improved; during the charging and discharging process of the battery, lithium ions will be consumed due to the continuous formation-destruction-formation of the SEI film (solid electrolyte interface film), which will eventually affect the cycle life

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