采用共沉淀法,制备了具有良好电化学性能的层状L iN i0.78Co0.2Zn0.02O2正极材料,探讨材料的物理性质对其电化学性能的影响.结果表明:电极片涂膜的厚度对其放电比容量及循环性能有很大影响;粒径的大小对首次放比容量的影响不大,但对其长期循环性能的影响较大.材料的相变是放电容量衰减的主要因素之一,通过掺杂改性、优化制备工艺条件、控制材料的物理性质,有利于抑制相变,提高材料的电化学性能.
LiNiO2 and LiNi0.5Co0.5O2 cathodes for lithium-ion batteries were synthesized with co-precipitation method and their electrochemical property was characterized by Galvanostatic cycling. Meanwhile, plane-wave pseudopotential method base on density functional theory was used to calculate average cell voltage and the electronic structure of LiNiO2 and LiNi0.5Co0.5O2. The experimental and computational results showed that the average voltage of the cell decreased as Li-ion intercalated to the host cathode (discharge); The potential of LixNi0.5Co0.5O2 was higher than that of LixNiO2 (when 0.25≤x≤0.5). The calculations also indicated that the distortion of the NiO6 octahedron in LixNiO2 was decreased by Co-doped. During the Li-ion intercalates to the host cathode, the micro-structures of NiO6 and CoO6 in the LixNi0.5Co0.5O2 were mutually stabilized, the Jahn-Teller effect was weakened and the electrochemical properties of the materials were enhanced.
