Fei Xu,Hongtao Wang,Mengyi Wu,Jiangsai Nan,Ting Li,Shun-an Cao
Redox-active organic materials are potential cathode materials for material-sustainable and environment-friendly Li-ion batteries. As is one of the most prominent features for organic compounds, isomerism has a significant influence on their properties. Herein, we synthesize two isomeric pairs of poly(anthraquinonyl imide)s ( PAQI s) by a simple one-pot reaction, and investigate their electrochemical properties as Li-ion battery cathodes by cyclic voltammogram and galvanostatic discharge/charge cycling. The PAQI materials exhibit a high reversible capacity of 202 mAh g −1 and a stable cyclability with 80% capacity retention over 200 cycles, and a remarkable rate performance, suggesting a potential feasibility of these organic cathode materials for high-capacity Li-ion batteries. The discharge/charge potentials of these PAQI s are slightly lower than the monomers . A further comparison of these four PAQI s indicates the isomerism plays a significant role in the electrochemical performance of these organic electrode materials .
Temperature Rising Elution Fractionation (TREF) is effective for separating polyolefin resins according to crystallizability. A relatively low isothermal crystallization temperature is necessary to fractionate poly(1-butene) (PB-1) resin because of its slow crystallization kinetics . This study aims to investigate the influence of isothermal crystallization temperature of TREF on the fractionation and chain microstructure of eluted fractions for one poly(1-butene-co-ethylene) with 5.8 mol% ethylene. The resin is fractionated using P-TREF under four different isothermal crystallization temperatures, i.e. 0 °C, −5 °C, −10 °C, and −30 °C, and then the fractions are characterized by high-temperature gel permeation chromatography (HT-GPC), 13 C nuclear magnetic resonance spectroscopy ( 13 C NMR), and differential scanning calorimetry (DSC) to acquire their chain microstructure information. The isothermal crystallization temperature significantly affects the nucleation and growth of the crystals, which consequently results in differences in the relative content of eluted fractions. With the decrease of isothermal crystallization temperature from 0 °C to −30 °C, the copolymer is fractionated more effectively since fractions are more evenly distributed among elution temperatures rather than concentrated at lower elution temperatures. Furthermore, the isothermal crystallization temperature influences the chain microstructure of fractions obtained at the same elution temperature, which are different in ethylene content, isotacticity, and average sequence length. The distribution of ethylene content and isotacticity becomes broader with the decrease in isothermal crystallization temperature. Lower isothermal crystallization temperature is conducive to effective separation of the fractions with weak crystallizability. These results are of great significance for the selection of fractionation conditions and chain microstructure analysis of poly(1-butene-co-ethylene) resins.
危险品化学品经营许可证（带存储）