Preparation Of Spinel Li-Mn-Oxide Cathode Material For Lithium-ion Batteries And Its Property Studies

Salt Lake rich in inorganic materials is one of the best resources of the world. There are many salt lakes in china, especially in the west of china, such as Qinghai, Tibet, Sinkiang, etc.. With the advance of West Exploitation, research on the industrialization of Salt Lake has become one of the hotspots in Inorganic Chemistry.Due to its efficient, convenient, pollution-free and economic advantages, lithium ion battery has been used to provide power for miniature portable electronic devices, electric vehicles (EV) and so on. And, the large share market of it provided a good chance for the lithium resources in Qinghai. Presently, the major materials that have been used as cathode were layered LiCoO₂, LiNiO₂ with α-NaFeO₂ structure and LiMn₂O₄ with spinel structure. Among these lithiated transition metal oxides, because of its abundant resources, low cost, high cell voltage and environmental friendliness, spinel LiMn₂O₄ was considered to be the most promising material. However, the capacity fading hinders its commercial applications. The main reasons for its capacity loss are the dissolution of Mn²⁺, Jahn-Teller effect, the decomposition of the electrolyte and the bad performance at the high temperature.To improve the cycling performance of spinel LiMn₂O₄, many strategies have been pursued, such as the partial substitution of manganese with Co, Cr, Al, Ni, Cu etc., and the partial substitution of oxygen with F or S; surface modification of the spinel articles by B₂O₃, LiCoO₂, SiO₂, C etc..The main work and results of the research was as follows:1. A new way called the low-temperature quasi-solid state method was used to prepare pure-phase Li-Mn-Oxide for lithium ion battery. TG-DTG, XRD, FTIR SEM were used to characterized the process of the synthesis, and the results showed that: the spinel was synthesized at the low temperature of 280℃; the single-phase spinel could be obtained at 480℃ and the well crystallized Li-Mn-Oxide was gained by using the step of high-temperature cystalling. The result on cycling performance was good. And, this method was homogeneous and environmental-friendly.2. Based on the theory of crystallography and aerodynamics, theambi-autoconvection baked technology that could be used for the industrialization of 10 t/a Li-Mn-Oxide was built. The products were high purified and well-distributed. And the electrochemical cycling test demonstrated that the charge/discharge capacity was high (about 1 lOmAh ? g"1) and the cycling performances were stable.3. By the experiment on many conditions, such as the selection of acid, antioxidant and so on, a method that could be used for the quantitative analysis of Mn and Co was confirmed. The results showed that this method was efficient and accurate.