Method for recycling positive material from water-system waste lithium iron phosphate battery

Abstract

The invention discloses a method for recycling a positive material from a water-system waste lithium iron phosphate battery. The method comprises the following steps: elaborately disassembling fully-discharged waste lithium iron phosphate battery to obtain an undamaged positive plate, separating a positive active material from a current collector in a way of immersing through deionized water, and drying and ball-milling the active material to obtain a lithium iron phosphate positive material to be recycled; respectively testing carbon content and ratio of Li, Fe and P elements of the lithium iron phosphate positive material to be recycled, adding a lithium source and an iron source, adjusting a mole ratio of Li to Fe to P to be (1.0-1.1):1:1, further adding the lithium source, the ion source and the phosphate source according to a ratio of 1:1:1 and adjusting C content ratio in the material; and performing ball milling, low-temperature pre-sintering and high-temperature sintering on the material of which ratio of the elements is adjusted to obtain the recycled lithium iron phosphate positive material. The recycled material has the advantages that 0.1C discharging capability can reach up to 156mAh / g, 2C discharging capability can reach up to 120mAh / g, the retention ratio of 0.1C discharging capability after 50 times of recycling is greater than 99% and various electrochemical properties are excellent. The method disclosed by the invention is low in cost and simple in process; the secondary pollution is avoided.

Description

technical field [0001] The invention relates to a method for recovering and regenerating positive electrode materials from water-based waste lithium iron phosphate batteries, and belongs to the field of recycling waste lithium ion batteries. Background technique [0002] Lithium-ion batteries have excellent characteristics such as high working voltage, high energy density, long cycle life, low self-discharge rate, low pollution, and no memory effect. They are the research and development and application hotspots of secondary batteries in the world today. With the increasing use of lithium-ion batteries, the number of waste lithium-ion batteries due to end-of-life is also increasing. The electrolyte in waste lithium-ion batteries is mostly LiPF 6 The organic ester solution has serious pollution to the environment. Among them, LiPF 6 Easy to react with water, when the moisture content is ≥10×10 -6 HF, LiPF can be generated in the environment 6 It can be decomposed at 60°C...

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Problems solved by technology

[0004] Patent CN102017276A (a method for recycling waste lithium iron phosphate power batteries), the positive plate disassembled from the waste battery is directly used, and the new negative plate is combined with the new negative plate to make the battery again. For batteries with reduced battery capacity, it is difficult to accurately judge whether the positive electrode sheet in the used battery can continue to be used normally, and it is easy to cause a high scrap rate after remaking the battery and waste resources; patent CN102285673A (a lithium iron phosphate power battery from Lithium and iron recovery method), focusing on element recovery rather than material regeneration, the recovery process is complicated and the economic benefits are not high; patent 201010253859 (a method for preparing lithium iron phosphate from waste lithium-ion power batteries in water system), patent CN101847763A (A method for comprehensive recycling of waste lithium iron phosphate batteries). The two follow the extensive crushing and recycling process of lithium cobalt oxide small batteries, which are easy to introduce metal impurities into the positive active material. In addition, they use the liquid phase regeneration process. , a large amount of acid-base reagents are introduced in the process, which will bring secondary pollution

[0005] Patent CN102208707 (a method for repairing and regenerating the positive electrode material of waste lithium iron phosphate battery) and patent CN102208706A (a method for recycling and regenerating the positive electrode material of waste lithium iron phosphate battery), aiming at the regeneration technology of waste materials, the liquid phase is used before sintering The ball milling method is used for mixing materials. In the process of material regeneration, the conductive agent and binder are completely removed as impurities by flotation separation, air classification or calcination method. The process route is relatively complicated.

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