Preparation of Cathode Active Materials for High Energy Density Lithium Secondary Battery and Their Characteristics for Batteries.

作为锂二次电池正极活性材料，V_2O_5和LiNiO_2是最有前途的候选材料。1)从VOSO_4溶液中电化学制备的V_2O_5 （e-V_2O_5）具有介于结晶V_2O_5 （c-V_2O_5）和非晶V_2O_5- p_2o_5 （a-V_2O_5- p_2o_5）之间的晶体结构和电化学行为。臭氧氧化法制备的V_2O_5 （O_3-V_2O_5）表现出与e-V_2O_5基本相同的特性。当截止电压为2.0 V时，e-和O_3-V_2O_5的放电容量均在250 ~ 260 mAh/g左右。这些值高于c-V_2O_5和a-V_2O_5-P_2O_5。采用恒流不间断技术和交流技术测量了4种V_2O_5阴极材料(D)中Li^+在不同放电阶段的化学扩散系数变化。在c-V_2O_5的情况下，D随着放电的进展而急剧变化。这种行为与文献一致，并得到了原位XRD测量的支持。a -V_2O_5-P_2O_5的D变化不大，表明该结构可以抵抗Li^+的插入破坏。与c-V_2O_5相比，e-和O_3-V_2O_5的D变化不是很大，直到x=0.8左右，之后D值减小。2)为了提高LiNiO_2的容量和可循环性，分别加入Fe、Mg和In制备LiFe_xNi_<1-x>O_2、LiMg_xNi_<1-x>O_2和LiIn_xNi_<1-x>O_2。在添加Fe和Mg的情况下，容量有所下降，而在添加In的情况下，linin_ <0.005>Ni_<0.995>O_2的容量增加到168 mAh/g，比LiNiO_2的164 mAh/g要大，并且可循环性也有所提高。In似乎在LiNiO_2中起结构稳定剂的作用。

As a cathode active materials for lithium secondary batteries, V_2O_5 and LiNiO_2 are the most promising materials among the candidates.1) Electrochemically prepared V_2O_5 (e-V_2O_5) from a VOSO_4 solution showed an intermediate crystal structure and electrochemical behavior between crystalline V_2O_5 (c-V_2O_5) and amorphous V_2O_5-P_2O_5 (a-V_2O_5-P_2O_5). V_2O_5 prepared by the ozone oxidation method (O_3-V_2O_5) showed almost the same characteristics as those of e-V_2O_5. The discharge capacities of e-and O_3-V_2O_5 are both about 250-260 mAh/g for ten cycles, when the cut-off voltage is 2.0 V.These values are higher than those for c-V_2O_5 and a-V_2O_5-P_2O_5. The chemical diffusion coefficient change of Li^+ in the cathode material (D) for four types of V_2O_5 was measured at various discharge stages by galvanostatic intremittent technique and AC technique. In the case of c-V_2O_5, D changed dramatically as discharge progressed. This behavior coincided with the literature and was supported by in situ XRD measurements. D of a -V_2O_5-P_2O_5 did not change so much, which suggests the structure is resistant to its destruction by Li^+ insertion. The change in D for e-and O_3-V_2O_5 is not very large compared to that of c-V_2O_5 till about x=0.8, after which the D values decreased.2) To increase the capacity and cycleability of LiNiO_2, Fe, Mg, and In were added to prepare LiFe_xNi_<1-x>O_2, LiMg_xNi_<1-x>O_2 and LiIn_xNi_<1-x>O_2. In the case of Fe and Mg addition, the capacity decreased, whereas in the case of In, the capacity of LiIn_<0.005>Ni_<0.995>O_2 increased to 168 mAh/g which is larger compared to 164 mAh/g for LiNiO_2 and cycleability was also improved. In seems to act as a structure stabilizer in LiNiO_2.