导离子型聚酰亚胺黏结剂的制备及其在锂离子电池正极中的应用研究  

Preparation of ionic conductive polyimide binder and its application in cathode of lithium⁃ion batteries

作　　者：钱秉筠 刘彩霞 朱唐宋 吴昊旻 张秋红 贾叙东[1] Qian Bingyun;Liu Caixia;Zhu Tangsong;Wu Haomin;Zhang Qiuhong;Jia Xudong(Key Laboratory of High Performance Polymer Material and Technology of MOE,Department of Polymer Science and Engineering,Key State Laboratory of Coordination Chemistry,School of Chemistry and Chemical Engineering,Nanjing University,Nanjing,210023,China)

机构地区：[1]高性能高分子材料与技术教育部重点实验室,配位化学国家重点实验室,南京大学化学化工学院,南京210023

出　　处：《南京大学学报（自然科学版）》2024年第4期661-673,共13页Journal of Nanjing University（Natural Science）

基　　金：国家自然科学基金(22075130,21875102)。

摘　　要：锂离子电池(LIBs)因其能量密度和输出功率高以及使用寿命长等优势,被广泛应用于新能源领域.正极用聚合物黏结剂作为LIBs的重要组成部分,在活性材料颗粒与电极集流体之间提供结合力,进而促进Li^(+)的扩散,对提高电池循环性能起着重要的作用.商用聚偏氟乙烯(PVDF)是目前正极材料中用到的主要黏结剂,但仍旧存在黏结性能低和导离子性较差的问题.聚酰亚胺(PI)具有优异的力学性能、黏附强度和良好的结构可设计性等优势.因此,设计并制备了一种具有磺酰亚胺锂结构的二胺单体(BAPSI-Li),将其与联苯四甲酸二酐(s-BPDA)和4,4'-二氨基二苯醚(ODA)共聚合成了一种导离子型PI黏结剂.研究表明,PI黏结剂黏结性能相比于PVDF有所提升.由导离子型PI黏结剂制备的LiFePO_(4)(LFP)电极具有优异的电化学性能,在0.2 C的电流密度下经250次循环后,放电比容量高达158.19 mA·h·g^(-1).导离子型PI黏结剂与商用PVDF黏结剂相比展现了更优异的循环稳定性.这得益于PI具有良好的黏结性能,电极能够在长循环过程中保持结构完整.同时,导离子二胺单体的引入有利于促进电极内部锂离子的传输.Lithium⁃ion batteries(LIBs)are widely used in emerging energy applications due to their advantages such as high energy density and output power,as well as long service life.Polymer binders used in the cathode play a crucial role in LIBs as they provide adhesion between active material particles and the electrode current collector,thereby facilitating the diffusion of Li^(+)ions and improving the cycle performance of batteries.Commercial polyvinylidene fluoride(PVDF)is the main binder used in cathode materials at present,but it still has the problems of low bonding performance and poor ion conductivity.Polyimide(PI),on the other hand,offers excellent mechanical properties,adhesive strength,and favorable design flexibility,making it an attractive alternative binder.Therefore,we designed and synthesized a sulfonimide lithium structure⁃based diamine monomer(BAPSI⁃Li),taking the advantage of excellent mechanical properties and structural tunability of PI.The BAPSI⁃Li monomer was copolymerized with 3,3',4,4'⁃Biphenyltetracarboxylic dianhydride(s⁃BPDA)and 4,4'⁃oxydianiline(ODA)to form an ion⁃conductive PI binder.The adhesive performance of PI binder was found to be improved compared to PVDF.The LFP electrodes prepared with this ion⁃conductive PI binder exhibited outstanding electrochemical performance,with a discharge specific capacity of 158.19 mA·h·g^(-1) after 250 cycles at a current density of 0.2 C.Compared with commercial PVDF binder,the ion⁃conductive PI binder demonstrated superior cycling stability.This was due to the excellent adhesive performance of PI,which enabled the electrode to maintain structural integrity during long cycling processes.Meanwhile,the introduction of the ion⁃conductive diamine monomer was beneficial for promoting the transport of lithium ions within the electrode.

关 键 词：锂离子电池 黏结剂 导离子聚合物 聚酰亚胺 LiFePO_(4)电极 

分 类 号：O63[理学—高分子化学]