Crystal Structure Analysis and Electrochemical Characterization of Nanosized Multicomponent Layered Cathode Materials Prepared via Soft Chemical Routes
Date Issued
2004
Date
2004
Author(s)
Lin, Yu-Kai
DOI
en-US
Abstract
Layered structure LiNi1/3Co1/3Mn1/3O2 was successfully synthesized via the reverse microemulsion (RμE) route. Well crystallized and nanosized (about 45 nm) powders were obtained after calcining at 800oC for 3 h. The results of Rietveld refinement and XAS shows the yield products had high degree of cationic ordering. At the voltage range of 2.5 V to 4.5 V, LiNi1/3Co1/3Mn1/3O2 can deliver 187.2 mAh/g at room temperature and 195.5 mAh/g at 55oC, respectively. The prepared powers had low irreversible capacity (< 6 %) and good capacity retention. Nanosized LiNi1/3Co1/3Mn1/3O2 exhibited better kinetic performance than solid-state derived powders, which was micron order size. Once the upper cut-off voltage was 4.6 V, the capacity faded rapidly compared to other upper voltage limitations, which would be related to the redox reaction of cobalt ions. The charge transfer resistance at 4.59 V was larger than other potential stages, which may result in incomplete charge compensation for cobalt ions.
Layered structure LiNi1/3Co1/3Mn1/3-yAlyO2 (0 ≦ y ≦ 1/3) was synthesized via the sol-gel method. Their electrochemical behaviors, while cobalt ions involved in the redox reaction completely, were investigated. XANES confirms that the valence of Co was 3+ and that of Ni was between 2+ to 3+ in LiNi1/3Co1/3Mn1/3-yAlyO2. The amounts of lithium ions that can be deintercalated were limited with aluminum concentration. However the extracting fraction of lithium ions was improved with aluminum content. The electrochemical inactivity of aluminum ions exhibited obviously until y over a specific range. That influenced the kinetic performance and the charge
compensation of cobalt ions so that leaded to unstable structure, rapid capacity fading, and low average voltage compared to undoped LiNi1/3Co1/3Mn1/3O2.
Subjects
奈米
鋰鎳鈷錳氧化物
陰極材料
層狀結構
鋰離子電池
Lithium-ion batteries
Nanosized
Cathode materials
Layered structure
LiNi1/3Co1/3Mn1/3O2
SDGs
Type
thesis