Several Sn-based Anode Materials For Lithium/Sodium Ion Battery

Large amount of hazardous substances from combustion of fossil fuel have been threatening people’s health. The clean energy such as solar power, wind power, tide power and so on is gradually substituting the status of fossil fuel as the society’s main power source in order to improve the ecological environment. Therefore, the energy storage has been paid attention more and more as a very important part in the field. The researchers put their eyes on the lithium ion battery according to its successful utilization in consumer electronics, which have the advantage of high energy density, high voltage, low self-discharging and outstanding cycle performance. On the basis, the relevant researches about their practice in larger scale energy storage like EVs and electrical grid have got some good results. But the poor abundance of lithium in crust and the high price of lithium sources will restrict their expanding use in the future. So the development of new batteries based on ions transportation is very necessary for the energy storage industry. Sodium ion battery is one of the candidates which is based on the sodium ion transportation, whose advantage comes from the tremendous sodium storage in crust and much cheaper price than lithium. Tin is one of few materials which can be used as anode in both lithium ion battery and sodium ion battery. Hence, it is highly worth researching for science and application. This thesis made the comparison between lithium ion battery and sodium ion battery about the electrochemical properties of composite thin film anodes based on tin. And the electrochemical reaction of tin-oxygen compound in sodium ion battery has been investigated.The composite tin thin films were fabricated by magnetron sputtering. For the pure tin thin film, the relationship between the1st cycle capacity lost and SEI capacity were studied. And the reason of SEI capacity evolution versus deposition time was explained, where the1st cycle capacity lost and cycle performance both decrease as the deposition time grown. Then, the tin thin film was utilized in sodium ion battery, and the potential plateaus and cycle performance in sodium ion battery were compared with lithium ion battery. The SEM testing result revealed that the large volume change is the main origin of cycle performance degradation. For the composite thin film, the addition of Cu, Ti, C made the flat potential plateaus of lithium ion battery into a slop curve, but effectively improve the cycle performance. Although it caused some tin inactive to lithium ion, this part of capacity lost was slight with respect to that of sodium ion battery. Furthermore, its improvement to the cycle performance of sodium ion battery was not obvious as much as it used in lithium ion battery. The radius of sodium ion is much bigger than that of lithium ion, resulting in the difficulty of sodium ion migration and larger volume change after sodium ion insertion.SnO2and SnO were fabricated by the decomposition of stannous oxalate (SnC2O4) and utilized as anode in sodium ion battery. The electrochemical reaction processes were deduced according to their reaction toward lithium. And the theoretical specific capacity was calculated in light of electrochemical reaction equation, which is quite larger than the experimental value. On the other hand, the cycle performance could be effectively improved when CNT was used as conductive agent. Ex-situ XRD was employed to indentify the compositions of the electrodes on the different discharing/charging state which indicates SnO2and SnO might have different reaction mechanisms.