Research On The Synthesis And Properties Of New Lithium Ion Battery Materials

In this dissertation, several new methods were developed to prepare and improve the properties of the electrode materials for lithium ion batteries on the basis of the review of previous work and a large amount of literatures. The electrochemical performances of as-synthesized electrode materials were investigated. The details are summarized as follows.1 A series of spinels LiSc_xMn_2-xO₄ (x = 0.01, 0.02, 0.06, 0.1) were synthesized by three-phase solid state reaction. The electrochemical tests indicate that the doping of Sc³⁺ can effectively improve the electrochemical properties of spinel LiMn₂O₄ as cathode materials. More than 90% of the initial capacity is reserved after 50 charge-discharge cycles in LiSc_xMn_2-xO₄, which is far more better than undoped spinel LiMn₂O₄.2 Nano-sized spinel LiMn₂O₄ particles were synthesized from Na-birnessite precursor by a LiBr refluxing method in hexanol at temperature as low as 80°C. The formation mechanism and electrochemical properties of as-synthesized LiMn₂O₄particles were studied. The results indicate that the as-synthesized LiMn₂O₄ shows nanoparticle morphology. After vacuum drying at 120 °C, the products show good electrochemical properties. The initial discharge capacity reaches 125 mAh/g, and more than 80% of the initials capacity remains after 30 cycles. The whole refluxing synthesis route has the superiority of low reaction temperature, short reaction time and low energy used. And, the hexanol used in reaction can be recycled in our route, which makes the method more economical.3 High-quality β-MnO₂ nanowires can be easily synthesized in large-area by using KNO₃ as mineralizing agents in the mineralization process from Mn(NO₃)₂ aqueous solution at 140°C. The formation mechanism is studied thoroughly. The results show...