Method for recycling waste lithium iron phosphate battery

Abstract

The invention discloses a method for recycling waste lithium iron phosphate batteries. The method comprises the following steps: (1) roasting: roasting to remove surface hydrophobic substances; (2) oxidation leaching: dissolving a Li metal element; (3) impurity removal: carrying out precipitating to remove Fe, Al and Cu elements in the filtrate; (4) lithium precipitation: precipitating and recovering a lithium compound; (5) phosphorus precipitation: precipitating the phosphorus element in the filtrate into ammonium magnesium phosphate hexahydrate; (6) growing of a carbon nano tube: introducing a gaseous carbon-containing substance to deposit and grow into the carbon nano tube; (7) pickling: removing the Fe element; (8) flotation separation: separating the carbon nanotube suspension from the graphite to obtain the carbon nanotube and the graphite. According to the method, the green and environment-friendly oxidizing agent is used, most of lithium and iron elements are selectively recycled to serve as catalysts for growing the carbon nanotubes, phosphorus is converted into slow-release fertilizer ammonium magnesium phosphate with good performance, waste graphite is recycled together, secondary pollution is avoided, and the problem that a traditional recycling process has negative economic benefits can be solved.

Description

technical field [0001] The invention belongs to the recycling technology of waste batteries, and relates to a method for recycling waste lithium iron phosphate batteries. Background technique [0002] Under the background of energy conservation, emission reduction, low-carbon and environmental protection, new energy vehicles have become the main direction of the future development of the automobile industry. With the strong support of national policies, the market share of new energy vehicles has been increasing year by year. Transition from initial stage to rapid development stage. As an important component of new energy vehicles, the demand for power batteries is also growing. Among them, the lithium-ion battery with lithium iron phosphate as the positive electrode has the advantages of high energy density, good cycle performance, high safety, and no memory effect, and is widely used in new energy vehicles. The huge amount of application will bring a huge amount of waste...

AI Technical Summary

Problems solved by technology

[0005] 1. The wet leaching process mentioned above often requires the use of strong oxidizing and strongly acidic substances such as hydrogen peroxide, hydrochloric acid, sulfuric acid, and nitric acid. The process is highly dangerous. If leakage occurs during the production process, it will cause environmental pollution. The corrosion resistance requirements for reaction equipment are high, and the equipment cost is relatively high

In the leaching step, because the lithium element is not selectively leached, other elements are also leached together, resulting in a large consumption of acid or alkali, complicated recovery process, and the recovered lithium carbonate product contains more metal impurities and cannot be used directly. Recycling as battery material

[0006] 2. The high-temperature calcined regenerated lithium iron phosphate process is relatively long, and requires strict testing and adjustment of the amount of additives added. The recovery process is difficult to control, and the regeneration reaction is uneven, which can easily lead to uneven product quality and unqualified products. Waste, and energy consumption is higher in addition, generally speaking, described two kinds of methods also have the shortcoming that economic benefit is poor, and graphite has not been effectively recovered, so practical application is very limited

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