| New energy vehicle market continued rapid expansion,led the lithium-ion battery demand soared,by 2020,the world’s waste lithium-ion battery will be more than 25 billion with more than 500,000 tons.At that time,Chinese production rate and the number of spent batteries will also exceed the average level of the world.As the lithium-ion battery cathode materials are the transition metal oxides,such as Li VPO4,Li Co O2,Li[Nix Coy Mnz]O2,which contains precious and scarce metals such as cobalt,nickel,lithium,etc.,as well as the current collector like copper and aluminum foil,so,recycling has a very high economic efficiency.Therefore,the harmless treatment for waste lithium-ion batteries and the metal recycling are of great significance.Recycling technology research will become the only way to environmental protection and resource regeneration.In this paper,the recovery and regeneration of spent lithium ion battery materials were studied.The content of impurity metal ions in the process of recovery was controlled by extraction,adsorption and precipitation.The optimum conditions were obtained.The effects of aluminum impurity content and supercritical technics on the physical properties and electrochemical properties of the prepared ternary cathode material Li Ni1/3Co1/3Mn1/3O2 were investigated.The optimal conditions for each method were determined in the study of metal ion impurity control.The results show that the Al3+ content can be effectively reduced by alkaline solution in the alkali solution.After three times of alkali washing,the mole percentage of aluminum ions decreases from 1.1 % to 0.6 %.The optimum extraction conditions of extractant A for Al3+ were p H = 2,O/A = 1:2,the concentration of extractant A was 50% vol,and the shaking time was 7 min.The optimum experimental conditions for the adsorption of Al3+ were p H = 4,the mass of adsorbent was m = 0.2 g,the temperature T = 25 ℃,and the adsorption time t = 1 h.The optimum extraction conditions of Cu2+ were as follows: pH = 3,O/A = 1:3,the concentration of extractant B and kerosene was 20 %vol,and the shaking time was 5 min.The optimum precipitation conditions of Cu2+ were p H = 2.5,the amount of precipitant was 7 ml,temperature T = 35 ℃,adsorption time t = 1.5 h.In the study of the recovery and regeneration of ternary cathode materials,the acceptable range of aluminum impurity content and the effect of supercritical conditions on the material were determined.The physical characterization results show that the prepared materials have uniform particles,and aluminum will replace the manganese and nickel.The electrochemical performances test results show that when x ≤ 0.03,the cathode material prepared by spent lithium ion batteries can meet the requirements of capacity and cycle performance.The introduction of supercritical technics has improved the performance of the material to a certain extent.From the view of electrochemical performance,the mateila with supercritical treatment in the first charge and discharge capacity,cycle performance and rate performance are better than untreated materials.After the supercritical treatment,the Rct and ΔEp of the material decrease obviously,which indicates that the electrochemical activity of the material is improved.It is good for the electrochemical reactions. |
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