酰亚胺基锂电池有机聚合物负极材料的制备及电化学性能研究

设计合成了一系列聚酰亚胺基的共轭骨架材料用于锂电池负极.首先,选用具有不同共轭体系的二酐分子用作共聚物构建单元,随后通过亚胺化反应与三聚氰胺共缩聚.最后,通过进一步热处理提高材料的交联程度和稳定性.将该材料用于锂离子电池负极表现出稳定的电化学性能.聚合物的倍率性能测试结果表明:在150 mA·g~(-1)的电流密度下,循环150次后,放电比容量达到471 mAh·g~(-1)以上,在2 A·g~(-1)的较大电流密度下,放电比容量达122.1 mAh·g~(-1),当电流密度返回至100 mA·g~(-1)时,其放电比容量又上升至532.3 mAh·g~(-1)左右,材料具有较好的倍率性能,聚合物材料在充放电过程中,避免了有机小分子材料在与锂离子结合后,易溶于电解液造成的容量损失.同时,共聚物骨架的共轭结构单元和极性基团,可在保证材料的导电性的同时增加材料结合锂离子的能力,因此表现出了优异的倍率性能.

Preparation of Organic Polymer Cathode Materials for Amide Lithium-ion Battery Anode and Their Electrochemical Performance

A series of polyimide based covalent organic framework materials for lithium batteries anode were designed and synthesized.In a first step,dianhydride,namely pyromellitic dianhydride (PMDA),and naphthalene-1,4,5,8-tetracarboxylic dianhydride (NTCDA) with different covalent organic frameworks were chosen to build blocks,which were utilized to polymerize with melamine to fabricate dianhydridebased polyimides (PIs).The obtained materials were heat-treated to improve their crosslinking degree and the stability.The materials showed a stable electrochemical performance when it was used in lithium ion battery cathode.The electrochemical test revealed that the material exhibited good durability,large reversible capacity and satisfied rate capacity.The result of rate capacity test showed that a reversible capacity of PI-1 of 471 mAh·g-1 was reached after 150 cycles at 150 mA·g-1,and the reversible capacity of PI-1 reached to 2 A·g-1 at 122.1 mAh·g-1,which could be maintained even at current density of 2 A·g-1,indicating that the material was of good rate capacity.Compared with the low molecular materials,the polymerization of the material avoided the decomposition during the redox process to improve the stability.Meanwhile,the high conjugated structural and polar groups on polymer was believed to have improve the electrical conductivity and the accommodation capability with Li ion.At the same time,the stability of the materials was increased by polymer crosslinking,resulting in the capacity loss in the process of charging and discharging of the lithium ion battery cathode,which was caused by the redox reaction.High degree of conjugate structure unit improved the carrier in the process of charging and discharging and the speed of the ion moving in and out.These materials would potentially afford a way to develop novel organic anode materials with excellent durability and rate capacity for LIBs.