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

高能量密度锂二次电池正极活性材料的制备及其电池特性。

基本信息

批准号：
05650834
负责人：
SATO Yuichi
金额：
$ 1.47万
依托单位：
Kanagawa University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

项目摘要

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.

作为锂二次电池的阴极活性材料，从VOSO_4溶液中电化学制备的V_2O_5（e-V_2 O_5）具有介于晶态V_2O_5（c-V_2 O_5）和非晶态V_2O_5-P_2O_5（a-V_2 O_5-P_2O_5）之间的晶体结构和电化学行为。臭氧氧化法（O_3-V_2O_5）制备的V_2O_5具有与e-V_2 O_5基本相同的特性。当截止电压为2.0V时，e-和O_3-V_2O_5的放电容量均为250-260 mAh/g，高于c-V_2 O_5和a-V_2 O_5-P_2O_5的放电容量。用恒电流间歇法和交流法测定了四种V_2O_5正极材料（D）中Li^+在不同放电阶段的化学扩散系数变化。在c-V_2 O_5的情况下，D随放电进行而显著变化。这种行为与文献相吻合，并得到了原位XRD测量的支持。α-V_2O_5-P_2O_5的D值变化不大，说明该结构对Li^+的插入具有抵抗破坏的能力。在x=0.8时，e-和O_3-V_2O_5体系的D值与c-V_2 O_5体系的D值相比变化不大，x=0.8后，D值减小。2）为了提高LiNiO_2的容量和循环性能，在LiFe_xNi_<1-x>O_2、LiMg_xNi_<1-x>O_2和LiIn_xNi_<1-x>O_2中分别加入Fe、Mg和In。在Fe和Mg的加入下，LiIn_ Ni_ O_2的容量降低，而在In的加入下，LiIn_<0.005>Ni_<0.995>O_2的容量从LiNiO_2的164 mAh/g增加到168 mAh/g，循环性能也得到改善。In在LiNiO_2中起结构稳定剂的作用。