Minimization of Capacity Fading in Li rich xLi2MO3-(1-x)LiMO2 Composite Cathode based on Defect and Computational Considerations
Abstract
Lithium-rich layered oxides have recently become attractive cathode materials for energy storage applications. Lithium-rich layered oxides, formulated as xLi2MnO3(1 - x)LiMO2 in which M representing Mn, Ni or Co receive great attention for both high-power and high capacity lithium-ion cells. However, there are obstacles such as structural stabilities and capacity fading for these cathode materials to be overcome. In this study, aliovalent doping such as Mo-doping into Li-rich layered oxide was found to be able to improve the conductivity,electrochemical performance and stabilized the structure of Li-rich cathode effectively. The Mo-doped Li-rich cathode 0.5Li2Mn1-xMoxO3-0.5LiNi1/3Mn1/3Co1/3O2 was successfully synthesized through sol-gel method. The XRD pattern showed that impurity phases identified as MoO3 as the content of Mo increases to x=0.05. The addition of Mo induces the reduction of Mn ion from +4 to +3 and the conductivity enhancement of the Li-rich cathode. The electrochemical test showed that the Mo-doped sample exhibited the highest cycling discharge and cycling performance among the test samples. In 0.5Li2Mn1-xMoxO3-0.5LiNi1/3Mn1/3Co1/3O2, the sample with X=0.025 exhibited 269mAh/g in the first discharge capacity and remained 224mAh/g after 30 cycles. While the undoped one shows 244.5mAh/g in the first cycle and then decayed to 202mAh/g after 30 cycles. The AC impedance results indicates that the Rct (charge transfer resistance) was reduced after Mo-doping. Such improvement may be also the reason why the Mo-doped sample exhibited the enhanced capacity performance, in particular, at high C-rate
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 06, 2018
- Accession Number
- AD1057187
Entities
People
- Kuan-zong Fung
Organizations
- National Cheng Kung University