新颖三明治状双层石墨烯包覆纳米粒子的复合结构的设计合成以及储锂协同增强效应的研究

电化学储锂反应中，储锂活性物质的结构完整性、电解液扩散、锂离子传输和电荷转移是影响储锂性能的关键性因素。针对此，本项目拟通过以葡萄糖为碳源、层状二维双金属磷酸盐水合物或者氢氧化物为牺牲模板，低成本高效的湿化学方法可控制备双层石墨烯包裹磷酸铁锂纳米粒子的三明治状复合结构，并考察其作为电极材料的电化学储锂性能。该目标产物具有结构新颖、纳米粒子粒径可调、石墨烯碳原子层数可控和可批量制备的特点。据判断，该产物不但具有以往石墨烯复合结构所具有的优点，如导电良好和比表面积较大，而且可以克服已知的缺点，如与电解液浸润性不佳、储锂活性物质容易团聚粉碎和离子传输困难等。双层石墨烯包覆功能纳米粒子-磷酸铁锂的复合结构将展现储锂的协同增强效应，大大提高储锂的倍率、循环性能以及单位体积和单位质量的能量密度，深入揭示该储锂协同增强效应将为新型高效储锂材料的设计制备和储锂理论的发展提供经典的研究模型和重要的理论依据。

In Lithium Storage, electrode materials' pulverization and agglomeration, electrolyte diffusion, Li-ion transportation and charge transfer are the key factors to determine the system's performance. Focused on this, the research proposal aims at developing one cost-effective and efficient wet-chemistry approach towards controllable synthesis of a novel sandwiched composite where doubly-layered graphenes are tightly encapsulating the functional nanoparticles-LiFePO4, with glucose as carbon source and 2-dimentional layered double-cation hydrated phosphates or hydroxides as sacrifacial templates, respectively. The targeted products exhibit properties of structural novelty, adjustable nanoparticles' diameter, tunable graphenes' atomic layers and high yield. By rationally tailoring the thickness of the precursor, 2-dimentional layered double-cation hydrated phosphates or hydroxides, concentration of carbon source, reaction temperature and time, etc., the designed samples with Li-storage activity would be achieved and subsequently will be investigated on the electrochemical Lithium storage performance. Presumably the composites harvested from the success of this project not only demonstrate good electronic conductivity and high specific surface area, which are the common advantages of graphene@active materials composites, but also can conquer some well-known disadvantages, such as problems of electrolyte's permeation, agglomeration and difficulties in ionic diffusion. Synergic effect of the sandwiched encapsulating composite on Li storage will considerably enhance the rate capability, cyclability, and volumetric and grammetric energy densities. To elaborate the synergic effect will pave a new avenue for the design and synthesis of efficient Li-storage materials, and provide an important model and basis for the development of Li-storage theory. The method to be developed here will also open up a gate for enriching the family of graphen-based functional materials.