Preparation Of Sn/Cu Integrated Collector And Its Application In Lithium Negative Electrode Materials

The core of the device battery car is lithium-ion battery, which is to protect the battery automotive power and endurance, so the development of battery vehicles also lithium-ion batteries made high-capacity, high-rate discharge and rate performance requirements. Currently the traditional graphite anode materials its good cycle performance, but it is lower than capacity, only 372 m Ah/g. New Sn based anode materials for high specific capacity, there are 993 m Ah/g, but its poor cycle performance. Therefore, the characteristics of traditional graphite anode materials and new negative electrode material, we have designed the Sn/Cu integrated collector,Sn-CNTs/Cu integrated collector, as well as a multilayer structure(C/Sn-CNTs/Cu)anode. In order to realize the commercialization application of(C/Sn-CNTs/Cu)anode material, we have conducted a systematical research to the structure and electrochemical properties of these these materials. The article mainly include the following innovative works:(1) Using the tin plating system designed by myself, under the current density of50 m A/cm2, we have made the electrodeposition experiments on the roughened electrodeposited copper foil with different electrodeposition times, the results show that the Sn/Cu integrated collector with the electrodeposition time of 15 s domenstrated the best battery capacity. At the rate of 0.1 C, it showed a capacity retention of 58.4% after 100 cycles. In addition, the study of its heat treatment process,showed that under the heat treatment condition of 80 ℃ for 12 h, the optimal battery capacity at 0.1 C appears with the capacity retention rate of 63.2% after 100 cycles,showing an improvement of 4.8 percentage points compared with that of Sn/Cu integrated collector, which has no heat treatment process..(2) Under the above mentioned optimum conditions, by using composite electrodeposition, we have introduce CNTs reinforced base to the Sn layer and assembled it to the battery. The electrochemical test show that at the rate of 0.1 C, it domenstrated an improved capacity retention of 74.6% after 100 cycles. Comparing to that(63.2%) of Sn/Cu integrated collector under the same conditions, it has improved11.4 percentage points. The assembled battery charging and discharging in high rate of 10 C showed a capacity retention rate was 72.3% after 30 cycles..(3) Coating graphite on Sn-CNTs/Cu integrated current collector prepares theC/Sn-CNTs/Cu anode material. The electrochemical test to the assembled battery,show that at the rate of 0.1 C, it has a capacity retention rate of 90.3% after 100 cycles.The specific capacity at this moment is 349.39 m Ah/g, improving 27.8%. Comparing to that of conventional graphite anode(273.82 m Ah/g). Conducting charging-discharging tests to C/Sn-CNTs/Cu electrode material showed that it has excellent rate performance with a capacity retention rate of 95% after cycling at different ratesIn summary, we have made an innovation to C/Sn-CNTs/Cu anode material with multilayer structure from the structure perspective, making it into an electrode material with the advantages of high cycle performance of the newly Sn anode material, as well as the excellect cycle performance of conventional graphite anode.