The rate and cycling performances of the electrode materials are affected by many factors in a practical complicated electrode process.Learning about the limiting step in a practical electrochemical reaction is very important to effectively improve the electrochemical performances of the electrode materials.Li4Ti5O12,as a zero-strain material,has been considered as a promising anode material for long life Li-ion batteries.In this study,our results show that the Li4Ti5O12 pasted on Cu or graphite felt current collector exhibits unexpectedly higher rate performance than on Al current collector. For Li4Ti5O12,the electron transfer between current collector and active material is the critical factor that affects its rate and cycling performances.
Five-period AlGaSb/GaSb multiple quantum wells(MQW) are grown on a GaSb buffer.Through optimizing the AlSb nucleation layer,the low threading dislocation density of the MQW is found to be(2.50±0.91)×10~8 cm^(-2) in 1-μm GaSb buffer,as determined by plan-view transmission election microscopy(TEM) images.High resolution TEM clearly shows the presence of 90°misfit dislocations with an average spacing of 5.4 nm at the AlSb/GaAs interface,which effectively relieve most of the strain energy.In the temperature range from T = 26 K to 300 K,photoluminescence of the MQW is dominated by the ground state electron to ground state heavy hole(el-hhl) transition, while a high energy shoulder clearly seen at T>76 K can be attributed to the ground state electron to ground state light hole(el-lhl) transition.
