多羰基聚酰亚胺正极材料的制备及其电化学性能

Preparation and Electrochemical Properties of Multicarbonyl Polyimide Cathode Materials

以3,3′,4,4′二苯酮四酸二酐(BTDA)和2,6二氨基蒽醌(DAAQ)为原料,采用溶剂热合成法制备多羰基聚酰亚胺(BTAQ)。通过改变溶剂的种类得到不同表面形貌的聚合物,利用傅里叶红外光谱(FTIR)、核磁共振仪(NMR)、扫描电子显微镜(SEM)等对其结构与形貌进行表征。将得到的聚合物作为锂离子电池正极材料,进行恒流充放电、循环伏安(cyclic voltammetry,CV)、交流阻抗等测试,以研究其电化学性能。结果表明,当聚合物溶液固含量为5%,并以N,N二甲基乙酰胺(DMAc)为溶剂时,所获得的聚合物可形成由均匀片状结构组成的"灯笼形"球体结构。这种结构有利于材料与电解液的充分接触,可加快离子的传输速率,从而提高多羰基聚酰亚胺的电化学性能,表现为较高的比容量和循环稳定性。在50mA/g的电流密度下,聚合物的首次放电比容量达到230.4mA·h/g,50圈充放电循环后保持在33.2mA·h/g,经过最高为500mA/g的不同电流密度充放电后,该材料表现出较好的倍率性能。

Multicarbonyl polyimide(BTAQ)was synthesized by the solvothermal method with 3,3′,4,4′-diphenylketotetraanhydride(BTDA)and 2,6-diaminoanthraquinone(DAAQ)as monomers.Polymers with different surface morphologies were obtained by changing the kinds of solvents,and their structures and morphologies were studied by Fourier transform infrared spectroscopy(FTIR),nuclear magnetic resonance(NMR)and scanning electron microscope(SEM).The polymers were used as cathode materials for lithium ion battery,and their electrochemical properties were investigated by galvanostatic charge-discharge,cyclic voltammetry(CV)and alternating-current impedance tests.The results show that when the solid content of polymer solution is 5%and N,N-dimethylacetamide(DMAc)is the solvent,a lantern-shaped spherical structure composed of laminated structure is obtained.The special structure could increase the contact interface between the electrode and the electrolyte,thus speeding the ion diffusions and improving the electrochemical properties,which induce a higher capacity and better cycling performance.When the current density is 50 mA/g,the specific discharge capacity of the polymer could reach 230.4 mA·h/g,and remains at 33.2 mA·h/g after 50 cycles.After charge-discharge testing under different current density with the highest current density of 500 mA/g,the material shows good rate performance.