Study On The Recycling Of Spent Alkaline Zinc Manganese And Spent Lithium Ion Batteries

In the present work, the preparation technologies of ferrite with good quality and nickel cobalt manganese（NCM） cathode materials for lithium ion batteries were investigated using spent alkaline manganese batteries and spent lithium ion batteries. Meanwhile, the dissolution conditions optimization and the treatment processes of spent alkaline manganese batteries and spent lithium ion batteries were also studied. These research work was carried out according to the preparation principle of liquid phase chemistry, the material chemistry synthetic principle and magnetic theory, using the spectrum method and micro structure analysis technique, and utilizing the knowledge of chemical technology, chemical reaction engineering and environmental engineering. All of the products were characterized by infrared spectroscopy（IR）, inductively coupled plasma atomic emission spectroscopy（ICP-AES）, X-ray diffraction（XRD）, thermogravimetric analysis/differential scanning calorimetry（TG/DSC）, scanning electronic microscopy-energy dispersive spectrometry（SEM-EDS）, transmission electron microscope（TEM）,vibrating sample magnetometer（VSM） technologies in the experiment. Proper preparation technologies were obtained according to the influence of preparation method on the the microstructure and magnetic properties of samples. The mechanism of dry gel self propagating combustion method and the mechanism of the sol-gel synthesis of materials were intruduced. The specific research contents and conclusions are as follows:（1） Firstly, the dissolution conditions of spent alkaline zinc manganese batteries in nitric acid solution were studied. The influencing factors on the dissolution rate of spent alkaline zinc manganese batteries in nitric acid were analyzed by the orthogonal experiment. The results showed the suitabledissolution conditions in nitric acid as following: nitric acid concentration, 6 mol/L; liquid-solid ratio, 13.6;hydrogen peroxide concentration, 2.5%; reaction temperature, 60℃; reaction time, 25 min. Then the combination of a sol–gel auto-combustion method and a microwave-assisted heating method was used to synthesize nanocrystalline MnZn ferrite powders using the solution of spent alkaline zinc manganese batteries treated in nitric acid and citric acid as gelling agent. The products were characterized by related techniques. IR spectra and DTA/DSC studies revealed that the combustion process was an oxidation–reduction reaction in which the NO3- ion was the oxidant and the citric acid was the reductant.The results showed that nanocrystalline MnZn ferrite powders were successfully prepared by a microwave heating method using MnZn ferrite precursor powders at 120℃ for 15 min. The MnZn ferrite powders prepared have higher saturation magnetization than that with the sol-gel auto combustion process alone,the ratio of saturation magnetization is 7:1.（2） At first, cathode materials of spent lithium ion batteries and Al foil would completely separate under the action of ultrasound using N-Methyl-2-pyrrolidone（NMP） as ultrasonic solvent. The cathode materials separated were calcined at 750℃ for 4 h in a muffle oven, the cathode materials after calcination was obtained. The cathode materials after calcination was digested by microwave digestion and was filtered, the microwave digestion residues were obtained. The composition, morphology and element distributions of the directly dismantled cathode materials, the cathode materials after ultrasound, the cathode materials after calcination and the microwave digestion residues were characterized by related techniques. The results showed the carbon and the PVDF in the cathode materials would be transformed into volatile components, the cathode materials after calcination basically could be dissolved completely during the microwave digestion. The mechanism of ultrasound was the ultrasonic cavitation accelerated convection movement. Next, the dissolution conditions of aluminum foil separated in the sodiumhydroxide solution were also studied. The suitable dissolution conditions of aluminum foil were as following: sodium hydroxide concentration 1 mol/L; reaction temperature 50℃; reaction time 15 min;solid-liquid ratio 0.05 g/mL; pH value 8. In addition, different types spent lithium ion battery separators were treated by dry ashing and microwave digestion as raw material, Zn, Pb, Cd, Mn, Fe, Mg, Ca, Cu, Na nine metal elements were determined simultaneously by ICP-AES. This study established an analytical method for the determination and treatment lithium ion battery separator. Detection results of metal elements in separator with ICP-AES were not quite different in two treatment processes and the element contents are different in different separator types. In the same separator, Ca and Na contents was the highest, Mg and Fe contents was in the middle, Cu and Zn contents was the lowest. The study provides basic data and analysis methods for the recycling of the metal elements in separators. At last,spinel-structured Co_0.8Fe_2.2O₄ was synthesized through a sol-gel method using the cathode materials of spent lithium ion batteries as raw materials and ethylene glycol or citric acid as a gelling agent. The structure, crystal form, morphology and magnetic property of the product were characterized by related techniques. The mechanism of ethylene glycol preparation cobalt ferrite was that the metal complex was formed by gels and metal reaction. With the increase of hydroxyl in solution, mixed hydroxide precipitation was generated, then cobalt ferrite was producted via calcination hydroxide precipitation calcined. The mechanism of citric acid preparation cobalt ferrite was that oxidation–reduction reaction happened during the sol–gel auto combustion process. The resulted also showed that the saturation magnetization of Co_0.8Fe_2.2O₄ cobalt ferrite with ethylene glycol and citric acid as a gelling agent were61.96 emu/g and 52.49 emu/g respectively. The saturated magnetization of Co_0.8Fe_2.2O₄ cobalt ferrite were 58.65 emu/g with citric acid as a gelling agent through nickel-doping. The reason of increasing the saturation magnetization of cobalt ferrite is that nickel radius is smaller than cobalt ion and nickel ionseasily occupy the cobalt ions in Tetrahetral in A, which improve the degree of order in the arrangement of ion crystal.（3） Li Ni1/3Co1/3Mn1/3O2 cathode materials of lithium ion batteries were successfully re-synthesized using mixed spent alkaline zinc manganese batteries and spent lithium ion batteries as the raw materials.These materials were synthesized by using a combination of dissolution, co-precipitation, calcination,battery preparation, and battery charge-discharge processes. The phase composition, morphology, and electrochemical performance of the products were determined via ICP-AES, FT-IR, XRD, SEM-EDS and Land tests. The results showed that LiNi_1/3Co_1/3Mn_1/3O₂ cathode materials could be successfully re-synthesized at optimal preparation conditions: co-precipitation pH value of 8, calcination temperature of 850°C, and calcination time of 10 h. Furthermore, the electrochemical results showed that the re-synthesized sample could deliver an initial discharge capacity of up to 160.2 mAh/g and Coulomb efficiency of 99.8%.