基于微控共轭聚合物的多孔硬炭及其复合物负极材料的结构调控与储锂特性研究

Hard carbon anode materials has high irreversible capacity and poor cycling life which greatly restrict their application as anode materials for lithium ion batteries.In order to furthest overcome these drawbacks of hard carbon,we proposed here for preparation of a series of novel porous hard carbon(PHC) carbonized form conjugated microporous polymers with high capacity,high rate, long cycling life as anode for lithium ion batteries. The structure of the PHC can be controlled by the structure of conjugated microporous polymer (CMP), and then the structure of CMP can be tuned by using various as-synthesized monomers or selection of their mole ratios during polymerization procedure. The electrochemical performance of PHC as anode for lithium ion batteries will be evaluated. The effect of porosity properties between the PHC and CMP, porosities of PHC and its electrochemical performance, as well as mechanism of action metal oxide and PHC and its electrochemical performance will be investigated. By combination with modern analysis/measurement, the relationship between the electrochemical performance and the structure of the as-synthesized PHC, and mechanism of action metal oxide and PHC and its electrochemical performance will be studied at the molecular level. The implementation of the proposed project will not only possibly develop novel, high performance anode materials with great potentials for practical use in the field of lithium ion batteries, but also provide basic experimental results and scientific evidence for further design, preparation of new structural anode materials for lithium ion batteries with high performance.

首次不可逆容量大、循环寿命差是硬炭负极材料的固有缺点，很大程度限制了硬炭锂离子电池负极材料的应用。为最大限度克服硬炭的这些缺点，项目拟通过合成新型单体及选择单体之间物质的量之比，来调控微孔共轭聚合物(CMP)的空间结构，进而调控其炭化产物（多孔硬炭）的空间结构，探索制备高性能多孔硬炭及其复合物负极材料，并考察其比容量、倍率性能、循环寿命等电化学性能。研究CMP和多孔硬炭的空间结构之间的关系、多孔硬炭的空间结构与电化学性能之间的关系、金属氧化物与多孔硬炭的作用机制及对复合物的电化学性能的影响。借助现代分析测试手段，在分子水平上揭示多孔硬炭的空间结构与电化学性能之间的构效关系、金属氧化物与多孔硬炭的作用机制与其电化学性能之间的关系。项目的实施不但可能得到高性能具有应用价值的多孔硬炭及其复合物负极材料，而且可为进一步设计、制备高性能新型结构多孔硬炭负极材料提供基础实验数据和科学依据。

与金属氧化物、硅和锡基等高容量负极材料相比，硬炭是最有前途的高容量锂离子电池负极材料。硬炭首次不可逆容量大、循环寿命差的固有缺点，很大程度限制了硬炭负极材料在锂离子电池工业中的应用。针对硬炭的这些缺点，项目合理设计了单体分子结构，通过Pd催化的单体末端炔基与卤代基团的Sonogashira-Hagihara偶联共聚反应，制备了纳米球状、微米球状、纳米管状微孔共轭聚合物（CMP）。将这些CMP炭化制备了纳米球状、微米球状、纳米管状多孔硬炭。系统研究了CMP和多孔硬炭的形貌、结构之间的关系以及多孔硬炭的储锂性能。发现多孔硬炭和CMP的形貌能够保持一致，即可以通过CMP来调控硬炭形貌。三种多孔硬炭中，纳米球状多孔硬炭具有最大的比表面积和最高的储锂容量。鉴于CMP含有丰富的碳碳三键，能够键合金属离子，选择纳米球状CMP和纳米管状CMP，吸附醋酸锰的乙醇溶液，将干燥后的两种复合物热解制备了嵌入MnO纳米颗粒的多孔硬炭纳米颗粒和多孔硬炭纳米管，两种材料都表现出了高储锂容量和稳定的循环性能。其中嵌入MnO纳米颗粒的多孔硬炭纳米管，1 C下循环300次后的比容量高达572.6 mAh/g。设计含氮单体，制备了纳米球状、管状含氮CMP，炭化后制备氮掺杂多孔硬炭纳米颗粒和纳米管。含氮CMP和氮掺杂多孔硬炭具有类似的形貌。两种多孔硬炭经KOH活化后，都具有高比表面积，储锂容量和首次可逆容量大大提高。其中KOH活化的含氮多孔硬炭纳米管，0.1A/g电流密度下首次可逆容量高达918.8 mAh/g。这些重要结果和数据为多孔硬炭在锂离子电池中的实际应用奠定了前期基础。