Phase Was Prepared Layered Of Lini <sub> 0.5 </ Sub> Mn <sub> 0.5 </ Sub> The O <sub> 2 </ Sub> And Electrochemical Properties Of,

On the base of reviewing the development of lithium ion battery and its cathode materials in details, layered LiNi_0.5Mn_0.5O₂ were chosen and their synthesis and modification procedures were studied. The preparation processes, particle size, crystallography characters and the electrochemical properties were characteried by means of DSC-TGA, XRD, SEM and electrochemical methods, and layered LiNi_0.5Mn_0.5O₂ with good performance were synthesized.Using NiCl₂·6H₂O and MnCl₂·4H₂O as major reactants, nickel-manganese composites were synthesized by the solid state reaction at room temperatures with three difference reactants ((NH₄)₂C₂O₄·H₂O, NaOH, Na₂CO₃·10H₂O). The precursors nickel-manganese oxides were synthesized by calcining different nickel-manganese composites. The effects of the species of reactants, the mixing order, the mole ratio of reactants were studied.Using the procursors and Li₂CO₃, layered LiNi_0.5Mn_0.5O₂ with different structure, surface and electochemical properties was synthesized by solid state reaction at high temperature. The factors such as types of precessors, tempereture and time to prepare procursors and LiNi_0.5Mn_0.5O₂ were explored in detail. The procursor obtained by decomposing nickel-manganese hydroxide at 500℃for 3h was the best source of Ni and Mn. Using this precursor, excellent LiNi_0.5Mn_0.5O₂ was synthesiced with Li/(Mn+Ni) molar ratio of 1.1 at 900℃for 12h. The optimized sample delivered 164.4 mAh·g^-1 between 2.5V and 4.3V at the current of 20 mA·g^-1 and it remained 91% of the initial capacity after 30 cycles. The electrochemical characters of this sample was studied by cyclic voltammetry and electrodemical impedance spectroscopy.