Hydrothermal Synthesis and Electrochemical Performance of LiNi_(0.5)Mn_(0.5)O_2 as Lithium-ion Battery Cathode

摘要

Hydrothermal method was successfully employed to synthesize LiNi_(0.5)Mn_(0.5)O_2 and the crystallinity of the resultant product was further improved by an annealing process. The structural information of the final product was analyzed by X-ray diffraction (XRD) and Rietveld refinement. The results showed that the Li/Ni exchange rate of hydrothermal samples was lower than traditional solid state method. Because of the improvement of the crystallinity the capacity of the annealed product was much better than that of the as prepared hydrothermal product. The capacity of annealed sample maintained 100mAh/g after 100 charge/discharge cycles. ICP-OES element analysis show that both hydrothermal and annealed samples are non-stoichiometric due to the existence of high valence Ni~(3+) and Mn~(4+) ions in LiNi_(0.5)Mn_(0.5)O_2 samples which might be largely responsible for the lower electrochemical capacity. Our work demonstrated that stoichiometric LiNi_(0.5)Mn_(0.5)O_2 with lower Li/Ni exchange could be synthesized by hydrothermal method when suitable oxidants were selected.