New progress in research of electrode materials for free radical stabilized sodium ion batteries

Recently, Lu Zhouguang's research group of materials science and Engineering Department of South University of science and technology published on-line the title of highly durable organic electronics for sodium ionbatteries via a stabilized α - C radial intermediate in nature Communications A new concept of improving organic electrode materials of sodium ion battery by free radical stabilization was proposed Organic sodium ion battery electrode materials have become potential substitutes for current commercial lithium ion battery electrode materials due to their transparency, flexibility, rich resources and easy functionalization, which are used in wearable electronic devices and large-scale energy storage and other fields The organic electrode materials, such as aromatic quinone, polyimide, Schiff base and carboxylate compounds, which are usually studied at present, have not only low capacity, but also short cycle life Therefore, the development of high capacity and high stability organic electrode materials for sodium ion batteries has important research value and application prospects The results show that the unsaturated groups such as C = O, C = n, and c-s-s-c are reduced to form C-O, C-N, C-S · radical intermediates It is easy to form dimer without redox activity, which leads to the rapid decay of organic electrode materials, which is the basic reason for the poor cycle life of organic electrode materials a: B: tricarbonyl compound dichloroisocyanuric acid the research group started from improving the reaction barrier and inhibiting the side reaction activity of free radicals, so as to develop the electrode materials of organic sodium ion batteries with high stability Using the X-ray absorption near edge structure spectroscopy of bl08u1a line station of Shanghai light source and the in-situ XRD method of bl14b1 line station, combined with the methods of EPR and charge discharge test, the mechanism of the stabilization of free radicals was studied in detail The mechanism of the formation, transfer, stability and electrochemical behavior of α - C free radicals was proved It is found that for most of the organic electrode free radical intermediates, the potential barrier △ E1 value is smaller than the electrode reversible reaction potential barrier △ EOX, and the side reaction activity is higher Increasing the reaction potential barrier of polymerization direction will effectively reduce the activity of this side reaction The conjugation effect of π system and free radical electron can effectively reduce the R · energy (△ E2), and the steric effect will increase the repulsion effect when the intermediate states are close to each other and then increase the intermediate state energy (E3) of R · - · R The stable α - c-benzyl radical was formed by π - π electron conjugation and the steric effect of aromatic groups on both sides of the radical This process not only improves the electrode capacity, but also greatly enhances the charge discharge cycle stability of the electrode This study proposes a general strategy for the design of long cycle stable organic electrode materials, which has important theoretical significance and industrial application prospects The important work of the quantum chemical calculation synchrotron radiation part of the Na + storage mechanism was completed in Shanghai light source, which was greatly helped and supported by bl08u1a and bl14b1 line stations of Shanghai light source The project is supported by the National Natural Science Foundation of China, the peacock program of Shenzhen, the foundation research of Shenzhen, the research initiation fund of South University of science and technology and the president's Fund.