The Structure-activity Relationship Of The Cathode Material With The XAFS

As one of the most important chemical-electrical energy conversion and storage devices, the rechargeable ions batteries have been widely used in many areas which have changed the world very much. However, with the development of science and technology, the fast-growing energy consumption leads to a higher requirement for ions batteries. It is very clamant thing to develop the next generation ions batteries. Since the Si/SiO2 anode has shown a great performance right now, the performance of the cathode materials becomes the key part to the new batteries. In addition, cathodes account for about 30%?40% of overall costs, in order to solve the problem in the cathode, it is not only a technical but also an economic issue. Furthermore, the price of the Lithium has increased very faster and faster, so using Sodium to replace Lithium shows more and more necessary. Lithium-rich layered transition metal oxides are considered as one of the most promising candidates for the next generation cathode materials due to their high energy density, high power density and high thermal stability.And the structure-activity relationship of the cathode material for sodium ions batteries have not investigated very clearly. In this paper, what we investigated is shown as follows:1. A layered structure Lii i5-xNi0.47TixSb0.38O2 composite is synthesized by the solid-state reaction method. In the as-prepared composite, it shows a great performance as the specific capacity reaches to 250 mAh/g, and after 500 cycles 83% capacity retains.When Ti element is doped into the composite, for the first time the experiment validates that Ti element occupies the octahedral site in the Li ions layer.2. A layered structure NaxRuO3(x=<1.8) composite is synthesized by the solid-state reaction method. It shows the specific capacity reaches to 200 mAh/g at 0.1C, and 93% retains after 500 cycles at lA/g. With the XAFS of the Ru, it is shown that the system tends to disorder status.3. The influence of the interstitial H2O in Na2FeFe(CN)6 has been investigated with XAFS. Which shows that the interstitial H2O is the most important key to the capacity attenuation in the Na2FeFe(CN)6.