| With the development of the industrial society and the improvement of the people living standard, the emergence of the battery provides great convenience to people’s life. So called battery has two branches, the narrow one is exchange chemical energy which stored by itself into electrical energy, the generalized one is exchange energy besides mechanical energy into electrical energy. Usually battery including 4 parts which are electrode, diaphragm, electrolyte and the shell, electrode and electrolyte, represents the basic composition of the battery, are the most important part of battery, battery is widely used for it is an important part of all kinds of electronic products. China owns more than 1400 battery production enterprise, being the largest battery production country in the world that China is the country in the largest demand for battery at the same time, battery emerges at various fields of people’s life.In the 1990 s, many countries began to develop nickel metal hydride batteries which been a new type of battery. This article mainly discusses the influence of waste nickel metal hydride batteries, it was known as the "green batteries" for its advantages of high power, high energy, circulating charge and discharge, suitable for high current discharge and less pollution. Nickel metal hydride batteries were used in battery pack to satisfy the need of portable electronic devices, and were well applied in all walks of life. For examples, portable printers, digital products, medical equipment, communications equipment and instrument, meters, mobile tools, LCD TV, electric cars and toys. Nowadays, with the increasing shortage of energy and the maturing of electric car technology, new energy vehicles have become a new trend in the future.Nickel metal hydride batteries contain large amounts of metal elements such as Ni, Co, Fe, Cu and Zn, but also contain rare earth metals such as La, Ce, Nd and so on. Positive electrode material of nickel metal hydride battery as the main object of study, it mainly contains Co, Ni, Fe and other metal elements, without rare earth metals. Valuable Ni and Co in batteries is the main objects to recycle. With a large number of waste nickel metal hydride batteries being discarded in life, environment pollution is more and more serious. Ni and Co in nickel metal hydride batteries is very expensive metals, so the comprehensive use of waste nickel metal hydride batteries has great value and significance meaning to both economic and environmental protection. When recycling waste nickel metal hydride batteries the technology is complex and the separation is difficult, metals in batteries are the mainly object to obtaining, which is the major material of the preparation of nickel and cobalt ferrite. Nickel and cobalt ferrite, with high chemical resistance and high saturation magnetization, is a kind of permanent magnetic material which has excellent performance, it is well used in vertical recording materials, low-loss core material and magnetic static wave devices, and so on.Through use inorganic acid and organic acid as the solute to discuss the dissolve performance of positive electrode material which contains in waste nickel metal hydride battery. In the best conditions use citric acid dissolve waste cathode material of nickel metal hydride batteries, and take advantage of the best condition in the preparation of nanometer-sized nickel cobalt ferrite. Research shows that: with sulfuric acid as solute, the initial concentration of sulfuric acid is 3 mol/L, the liquid-solid ratio 8:1, melting temperature is 85℃, the dissolving time of 25 min, under all the conditions above the dissolution rate of Ni and Co is as high as 94.15%. Use citric acid as solute and the concentration of citric acid 2 mol/L, liquid-solid ratio 8:1, solution temperature 90℃, dissolution time 50 min, the highest dissolved rate of Ni and Co is 84.56%. Under the optimum solution conditions by microwave method, in the PH=10, microwave digestion temperature 160℃, the reaction time of 1 hour, Ni0.5Co0.5Fe2O4 of better performance can be obtained. Analysis the characterization products from crystalline form, composition and morphology three aspects by ways of XRD and SEM, well-distributed nanometer crystals will be obtained, namely nanometer-sized nickel cobalt ferrite.Innovation point of this paper: the use of inorganic acid and organic acid as the solute, using the single factor and orthogonal test method, through analysis of range to explore the solution conditions that influence cathode material in waste nickel metal hydride battery. At the same time to select the best conditions that use citric acid as solute, to the preparation of nanometer-sized nickel cobalt ferrite by ways of microwave digestion. |
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