Fast chargeable lithium iron phosphate polymer lithium ion battery with ultra-high magnifications and manufacturing method thereof

Abstract

The invention relates to a fast chargeable lithium iron phosphate polymer lithium ion battery with ultra-high magnifications and a manufacturing method thereof. A fast chargeable lithium iron phosphate polymer lithium ion battery with ultra-high magnifications does not exist in nowadays. The fast chargeable lithium iron phosphate polymer lithium ion battery with ultra-high magnifications comprisesa positive electrode sheet, a negative electrode sheet, an isolation film and a polyethylene-aluminium compound film, and is characterized in that the positive electrode sheet is made of an positiveelectrode current collector and a positive electrode slurry, the positive electrode slurry comprises the following components by weight percent: 88%-93% of lithium iron phosphate, 0.2%-2.5% of conductive graphite, 1%-5% of carbon nanofibre, 0.1%-0.4% of dispersant and 3.8%-6% of polyvinylidene fluoride; the dispersant is a non-ion surfactant, the solid content of the slurry is 46%-52%, the slurryis uniformly distributed on the upper surface and the lower surface of the positive electrode current collector, and the surface density of the slurry is 15-20 mg / cm<2>. The invention has reasonable structure, stable performance, long service life and functions of the fast charging and the ultra-high magnification.

Description

technical field [0001] The invention relates to a lithium ion battery and a preparation method, in particular to a fast-chargeable ultra-high rate lithium iron phosphate lithium polymer lithium ion battery and a preparation method. Background technique [0002] Nowadays, batteries widely used in high-rate power products such as electric tools and automobile starting power supplies are still mainly nickel-cadmium, nickel-metal hydride and lead-acid batteries. Both nickel-cadmium and nickel-metal hydride batteries have memory effects, and regular discharge management is necessary. Improper operation will affect the performance of the battery. Therefore, cumbersome discharge management procedures are unavoidable during the use of nickel-cadmium and nickel-metal hydride batteries. Yes, this increases the workload during battery use. However, nickel-cadmium batteries and lead-acid batteries are heavy pollution processes from raw materials, production processes to waste recycling...

AI Technical Summary

Problems solved by technology

The positive electrode material of the existing lithium-ion battery is mainly made of lithium cobalt oxide, because the safety performance of lithium cobalt oxide battery is poor, and the temperature of the battery is high when the high current discharge is carried out, and the high temperature performance of lithium cobalt oxide itself Poor, long-term high-current discharge cycles of lithium cobalt oxide batteries will greatly shorten their service life, so lithium cobalt oxide batteries are not suitable for use in high-rate and high-power power battery products such as electric tools and car starting power supplies

[0004] Of course, using lithium iron phosphate materials to make electrode sheets can eliminate the safety hazards of lithium cobalt oxide batteries, but due to the characteristics of lithium iron phosphate materials, the processing performance of lithium iron phosphate materials is poor, and it is prone to powder removal and material loss. At present, in order to improve the processing performance of lithium iron phosphate materials, it is usually necessary to modify the lithium iron phosphate material, and then add more binders to the lithium iron phosphate material to make pole pieces.

However, the above method will affect the high conductivity of the manufactured lithium iron phosphate electrode sheet, resulting in the inability of the lithium iron phosphate battery to achieve high-rate discharge and high-current fast charging.

At present, in order to take into account the processing performance of the material, the existing lithium iron phosphate battery can only be discharged at a rate below 20C, and does not have the function of fast charging, and the required charging time is long, which cannot meet the requirements of electric tools and car starting power. Application requirements in the field of high-rate power products with high-rate and high-current continuous discharge

[0005] At present, there are also some relatively new methods of manufacturing lithium iron phosphate used as battery positive electrode materials. For example, in the Chinese patent with the application date of January 27, 2008 and the publication number of 101494288, a lithium ion secondary battery positive electrode is disclosed. The preparation method of the material lithium iron phosphate, the battery manufactured by using the lithium iron phosphate in this patent has the function of high-current discharge, but the lithium source compound, ferrous iron source compound, phosphorus source compound and small organic molecules in the patent The carbon source additive requires a high temperature during sintering, between 300-500 ° C, and the sintering takes a long time, which takes 5 to 15 hours; the sintering precursor is mixed with the organic polymer carbon source additive. The sintering temperature should also be between 600-800°C, and the time required is 5-20 hours

This makes the required energy consumption of the patent more, improves the production cost, and reduces the production efficiency

[0006] Another example is a Chinese patent with a publication date of January 11, 2008 and a publication number of 101483261, which discloses a high-power lithium iron phosphate battery and its manufacturing method. In this patent, submicron-sized lithium iron phosphate powder is used as the positive electrode The active material in the slurry, which makes the requirements for lithium iron phosphate higher, which greatly increases the production cost, and only relying on submicron lithium iron phosphate powder as the active material in the positive electrode slurry cannot achieve fast charging of the battery. and ultra-high magnification functions

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