Synthesis And Electrochemical Performance Of Mn-based Anode Materials For Lithium-ion Battery

In the last few decades, rapid growth in needs of lithium ion batteries(LIBs) for portable computers, hybrid electric vehicles(HEVs), pure electric vehicles(EVs) and plugin hybrid vehicles(PHEVs) have required the drastic enhancement of its capacity and energy density. Among the candidates, metal oxides have attracted much attention due to their advantageously high capacities. Though high capacities binary oxides have, there are also some problems, such as their poor electrical conductivity and severe volume expansion during discharge/charge process. In this dissertation, nano-structure materials and composite transition oxides materials were synthesized to improve the electrochemical performance. The main contents are described as follows.1. Nano-structure Zn Mn2O4 was synthesized via facile spry drying method and annealing method. The result of XRD revealed that all the 2θ values and relative peak intensities of the diffraction peaks are in full accord with the standard Zn Mn2O4 spinel structure(JCPDS File Card No. 71-2499) in the cases of ZM400 and ZM600. SEM observation showed that we success in synthesizing Zn Mn2O4 with particle size about 100 nm which is most proper to Zn Mn2O4. The electrochemical test demonstrated that the sample ZM600 had the highest coulombic efficiency(CE)(70.6%) and the best cycleability(remained discharge specific capacity about 860 m A h g-1 after 160 cycles). The rate performance of sample ZM600 was also excellent. Even at a high current density of 1600 m A hg-1, the capacity was still 382 m A h g-1 which is higher than the theoretical capacity of commercial graphite(372 m A h g-1).2. A facile spray drying method and annealing method has been developed for the synthesis of Cu1.5Mn1.5O4. Cu1.5Mn1.5O4 has first been reported as an anode material for LIBs, which exhibits good electrochemical performance with a high specific charge capacity of 464 m A h g-1 after 60 cycles at the current rate of 100 m A h g-1. The involved reaction mechanism of Cu1.5Mn1.5O4 has been investigated and demonstrated as the conversion reaction mechanism by CV and XPS analysis. In addition, the calcination temperature of as-prepared samples has been explored to optimize the electrochemical performance. The as-prepared SD700 displays a good performance and is considered as a promising anode material for lithium ion batteries.