基于剑麻纤维富氮类石墨烯高倍率锂离子电池负极材料的制备和电化学性能研究

Grapheme-like anode materials for lithium ion battery often have disadvantages of large irreversible specific capacity, voltage hysteresis and uncontrollable conductivity. In order to solve these problems, in this project, graphene-like materials from sisal fibers will be prepared, the reason is sisal fibers have special internal structure with layered and natural pores, and are rich in cellulose and are characteristic resources in Guangxi province. Nitrogen- rich grapheme-like materials for high rate, high capacity and high cycle lithium ion battery anode will be created by nitrogen doped and nanocomposite modified. In order to get the optimization synthetic condition, effects of synthesis conditions including hydrothermal temperature and time, pH value, activating agent and dosage, activating temperature and time, the growth age, different parts and pretreatment method of sisal fibers on the morphology, structure, element content and distribution and electrochemical performance of anode materials will be investigated. The focus is on the formation mechanism of the grapheme-like nanostructures in the hydrothermal, activating and modified progress, and the effects of the nitrogen-doped and nanocomposite modified on the microstructures, morphology and the electrochemical performance of anode materials, which is to determine the regulatory mechanism of microstructures on the electrochemical properties of anode materials. These studies will provide a theoretical basis for the application of new anode material for lithium ion battery with high performance, low cost and environment-friendly green approach.

为了解决锂离子电池负极材料-类石墨烯材料不可逆比容量大、电压滞后及导电性不可控问题，本项目拟以广西特色资源-剑麻纤维作为碳源，利用其层状和自然孔隙的特殊结构及富含纤维素的化学成分，制备剑麻纤维类石墨烯。通过掺氮及纳米复合改性，获得高倍率、高容量和高循环性能的纳米铁氧化物/剑麻纤维富氮类石墨烯锂离子电池负极材料。探讨合成条件（水热温度及时间、酸碱度、活化温度及时间、活化剂类型及含量等）及剑麻纤维的生长年龄、生长部位及预处理方法对负极材料的形貌、结构、元素含量和分布及电化学性能的影响，获得最佳纳米铁氧化物/剑麻纤维富氮类石墨烯锂离子的制备工艺；重点研究剑麻纤维类石墨烯在水热、活化及改性中的形成机理，探讨掺氮和纳米改性对负极材料的微观结构、形貌及电化学性能的影响，确定材料微观结构对电化学特性的调控机制，获得调控参数。项目研究将为高性能、低成本及绿色环保的新型锂离子电池负极材料的应用提供理论基础。

为了解决锂离子电池负极材料-类石墨烯材料不可逆比容量大、电压滞后及导电性不可控问题，本项目以广西特色资源-剑麻纤维作为碳源，利用其层状和自然孔隙的特殊结构及富含纤维素的化学成分，制备了超薄(2nm)的类石墨烯剑麻纤维炭（SFAC）锂离子电池负极材料。通过杂原子（N，S，P）掺杂及纳米复合改性，获得了一序列高倍率、高容量和高循环性能的N,S-SFAC、N,P-SFAC、MoS2/SFAC、SFAC/MoS2/PANI、MoSe2/N,P-SFAC等基于SFAC改性的纳米结构材料及基于其他形貌剑麻纤维炭（SFC）改性的N-SFC、N,S-SFC、铁氧化物/SFC、S/SFC、MoSe2-MoO2@SFC、MoS2/SFC、CuS@SFC、Mn基金属氧化物/SFC等纳米结构材料。探讨了合成条件（水热温度及时间、体系酸碱度, 活化剂、活化温度及时间、煅烧温度及时间等）及剑麻纤维的生长年龄、生长部位及预处理方法对负极材料的形貌、结构及电化学性能的影响，获得负极材料的最佳制备工艺。重点研究了剑麻纤维类石墨烯在水热、活化及改性中的形成机理，探讨了N,S,P等杂原子掺杂和纳米改性对负极材料的微观结构、形貌及电化学性能的影响，确定材料微观结构对电化学特性的调控机制，获得调控参数。揭示了杂元素掺杂剑麻纤维类石墨烯纳米复合材料的形貌、结构与其电化学性能之间的关系，获得了提高剑麻纤维炭负极材料的可逆比容量、循环性能以及倍率性能等电化学性能的有效途径，为进一步改善电极结构、设计新型电极材料提供了借鉴，并为高性能、低成本及绿色环保的新型锂离子电池负极材料的应用提供理论基础。