基于过渡金属磷化物钾离子电池负极材料的可控制备及储钾机制研究

With the lithium scarcity, exploration of low-cost, high energy-density energy storage systems is of paramount importance. Potassium, an abundant alkali element in earth, offers a lower reduction potential compared to sodium, allowing potassium ion batteries (PIB) to operate at higher potentials, and thus showing great potentials in large-scale energy storage systems. This proposal intends to fabricate high-capacity transition-metal phosphide based anode materials for potassium ion batteries. In order to address the intrinsic issues of low conductivity and large volume expansion for phosphides during charge-discharge processes, three dimensional (3D) mesoporous carbon confined phosphide nanoparticles will be fabricated via electrospinning and controlled pyrolysis. The combination of high conductivity, large surface area and the flexible freestanding property of 3D mesoporous carbon network together with the nanoeffect of ultrasmall phosphide nanoparticles is expected to endow the PIB anode materials with high energy density, high stability and good rate capability. The controllable synthesis, the correlation between the structure of the mesoporous carbon network and the electrochemical performance will be investigated in detail. Advanced characterization techniques including in-situ XRD, in-situ Raman and in-situ TEM will be further studied to monitor the structure and the interfacial properties of anode materials, thus revealing the intrinsic potassium storage mechanism. On the basis of the experimental and analytical results, the electrode structure will be further optimized aiming to achieve higher performance PIBs. This work will provide theoretical and practical bases for the development of high-performance PIB anodes.

随着锂资源的稀缺，开发低成本、高能量密度的新型储能体系有着重要意义。同为碱金属的钾储量丰富，相比于钠有更低的标准还原电势，使得钾离子电池在大规模能量储存有着广阔的发展前景。本项目拟构筑基于高容量过渡金属（Fe、Co、Ni）磷化物的钾离子电池负极材料。针对磷化物低电导率、充放电过程中体积膨胀大等关键科学问题，拟通过静电纺丝及可控热解，在三维多孔碳纤维骨架上原位生长磷化物纳米颗粒。结合多孔碳的高电导率、高比表面积、柔性自支撑等优势及纳米化磷化物的小尺寸效应，以期实现高能量密度、高倍率性能且稳定性良好的钾离子电池负极材料。可控制备三维多孔碳限域磷化物的复合纤维膜，并研究其结构对材料电化学性能的影响，结合先进的原位表征技术（XRD、Raman、TEM），实时监测材料微结构及电极表界面的物理化学性质在充放电过程中的演变规律，揭示储钾机制，并在此基础上优化电极结构设计，为钾离子电池的研究奠定科学基础。

随着锂资源的稀缺，开发低成本、高能量密度的新型储能体系有着重要意义。同为碱金属的钾储量丰富，相比于钠有更低的标准还原电势，使得钾离子电池在大规模能量储存有着广阔的发展前景。碳基材料具有结构可调、电化学性能优异、成本低、可大规模应用等特点，是钾离子电池的重要且有应用前景的负极材料。本项目以热解碳基材料的可控制备、结构调控和性能优化为核心，系统探究前驱体材料的结构和热解条件对热解碳电极材料结构与电化学性能的构效关系，可控制备了介孔碳纳米线、富缺陷的微孔碳纳米片、以及具有丰富异质界面的三元碳基复合材料，在包括钾离子电池在内的多种碱金属离子电池中展现出高容量、高倍率、长循环等优异的电化学性能。结合先进的原位表征技术（XRD、Raman、TEM），实时监测材料微结构及电极表界面的物理化学性质在充放电过程中的演变规律，揭示储能机制，并在此基础上优化电极结构设计，为钾离子等碱金属离子电池的研究奠定科学基础。