1,5-二氨基蒽醌(AAQ)复合材料用作锂离子电池新型正极材料的性能研究

Studies on the Properties of 1,5-Diaminoanthraquinone(AAQ)Composite Used as New Positive Electrode Material in Lithium Ion Batteries

有机共轭小分子材料1,5-二氨基蒽醌(AAQ)作为锂离子电池的一种有机正极材料,由于其制备简便、理论比容量较高和循环性能比较稳定等优点,成为新能源电池材料的研究重点.然而,由于其本征材料导电性较差并在电解液中存在溶解等现象,影响了其电化学性能,从而限制了其进一步的应用.本工作采用超声法将AAQ分散在金属有机骨架多孔材料(MOFs)-氮掺杂多孔碳(ZIF-8C)内,再通过高温熔融法制备了多孔碳骨架复合材料AAQ@ZIF-8C;并通过溶液聚合法,制备出了聚丙烯酸(PAA)和聚苯胺(PAN)有机结合的共混物(PAA-PAN);最后通过球磨法将上述材料混合,制备出AAQ@ZIF-8C/PAA-PAN复合电极材料,并通过红外光谱、扫描电子显微镜、电化学循环伏安法及交流阻抗法等对复合电极材料分别进行了结构表征、形貌分析及电化学性能测试. PAA-PAN与AAQ@ZIF-8C结合后,形成了导电互穿网络结构,既提高了电极活性材料AAQ的导电性,同时又抑制了AAQ在电解液中的溶解性;另外,具有多孔的ZIF-8C骨架材料有利于电解质离子的快速扩散和迁移,提高了电池的可逆容量.用该复合电极材料组装的锂离子电池,在0.1C库伦倍率下充放电,可逆容量达203mAh·g^(-1),接近其理论比容量225mAh·g^(-1),经过200次循环后,可逆容量仍达195 mAh·g^(-1),库仑效率达95%.

Organic conjugated small molecular material 1,5-diaminoanthraquinone(AAQ),as an organic cathode material for lithium-ion battery,has become the research focus of new energy battery materials because of its simple preparation,high theoretical specific capacity and stable cycle performance.However,due to its poor conductivity and dissolution in electro-lyte,its electrochemical properties are affected,which limits its further application.In this work,AAQ was dispersed in metal organic framework porous materials(MOFs)-Nitrogen-doped porous carbon(ZIF-8C)by ultrasonic method,and then po-rous carbon framework composites AAQ@ZIF-8C were prepared by heat-treatment method.Copolymer PAA-PAN was pre-pared by solution polymerization method with polyacrylic acid(PAA)and aniline(AN)monomer.Finally,AAQ@ZIF-8C/PAA-PAN composite electrode material were prepared with above materials by ball milling method.The structure,morphol-ogy and electrochemical properties of the composite electrode materials were characterized by infrared spectroscopy,scan-ning electron microscopy,electrochemical cyclic voltammetry and AC impedance method.When PAA-PAN combined with AAQ@ZIF-8C,the conductive interpenetrating network structure is formed in AAQ@ZIF-8C/PAA-PAN composite,which not only improves the conductivity of the electrode active material AAQ,but also inhibits the solubility of AAQ in the elec-trolyte.In addition,the porous ZIF-8C skeleton material is conducive to the rapid diffusion and migration of electrolyte ions and improves the reversible capacity of the battery.High solubility in aprotic organic electrolytes and poor electrical conduc-tivity are the main restrictions of organic electrodes in practical application.Conductive binder contributes to the high-performance electrodes as it enables both mechanical and electronic integrity of the electrode,which have been scarcely explored for organic electrodes.As we know,state-of-the-art lithium-ion battery(LIB)electrodes choose polyvinylidene fluo-ride(PVDF)as the binder because of its good chemical and electrochemical stability.Herein,a conductive interpenetrating polymeric network is synthesized through in situ polymerization of polyaniline with poly(acrylic acid)(denoted PAA-PAN),which served as a novel conductive binder for organic AAQ materials.The PAA was chosen as the matrix component for the reason that PAA contains sufficient carboxyl groups(-COOH),which can condense with the amino groups(-NH2)of poly-aniline.Therefore,a conductive interpenetrating network can be formed in the process of in-situ polymerization.The conduc-tive PAN component enhances the electrical conductivity of the electrode.Meanwhile,the PAA component serves as the binding matrix to condense with the amino groups(-NH2)of AAQ,which therefore effectively inhibits their dissolution and maintains electrode integrity during cycling.The electrochemical results showed that the lithium ion battery assembled with the composite electrode material has a reversible capacity of 203 mAh•g^(-1) at a Coulomb rate of 0.1 C,which is close to its theoretical specific capacity of 225 mAh•g^(-1).After 200 cycles,the reversible capacity is still 195 mAh•g^(-1) and the coulomb efficiency is 95%.