温度梯度溶剂热自模板法制备中空WS2@C核壳结构及其储钠机理

类石墨层状WS2是一种理想的钠离子电池负极材料，在电子设备等能量储存领域具有广阔应用前景。然而其低导电性和充放电过程中的结构不稳导致其倍率和循环稳定性能较差，是亟待解决的难题。基于此，本项目设计了具有中空形貌物理限域的WS2@C核壳结构，利用中空和表面限域结构抑制WS2体积膨胀导致的结构不稳定，利用C包覆提高其导电性，协同解决循环稳定和倍率性能差的难题。拟采用温度梯度溶剂热自模板法来构建中空WS2@C结构，先在不同形貌有机模板表面低温自组装WS2纳米片；然后升温使模板消解，形成中空WS2组装体；之后将溶解的模板在高温下碳化，在组装体表面沉积C包覆层，获得中空WS2@C核壳结构。通过优化工艺、结构和性能，探索中空结构、碳掺杂、表界面和晶体结构的调控机制；阐明电化学原理，揭示循环稳定性和倍率能力的协同提升机制，建立结构-储钠机理-性能的关系模型，进一步提升WS2的电化学性能和拓宽其应用领域。

Graphite like layered WS2 is an ideal anode material for sodium ion battery, which has a wide application prospect in energy storage field such as electronic equipment. However, the grain pulverization and low conductivity in the process of charging and discharging lead to the poor cycle stability and rate capability. Therefore, simultaneously improving the cycling stability and rate capability of the WS2 is a problem that should be solved urgently. In order to solve this problem, this project designs a hollow WS2@C core-shell structure with physical confinement. The hollow and surface confinement structure is used to reduce the pulverization caused by the volume expansion of WS2, and the coating carbon layer is used to improve its conductivity, so as to solve the problem of cycle stability and poor rate capability. It is proposed to synthesize hollow WS2@C structure by temperature gradient self-template solvothermal reaction. At first, WS2 nanosheets are self-assembled on the surface of organic template with different morphology at low temperature. Then, hollow WS2 assembly is achieved by dissolving the template at high solvothermal temperature. Finally, the hollow WS2@C structure is obtained based on the dissolved template carbonization at a higher temperature to form carbon layer on the surface of the assembly. According to the optimizing of preparation process, structure and electrochemical performance，the cooperative regulatory mechanism of hollow structure, surface/interface and crystal structure will be explored, the electrochemical reaction mechanism will be illuminated, the synergistic enhancement mechanism of cycling stability and rate capability will be revealed. The relationship model of hollow core-shell structure, Na+ storage mechanism and electrochemical performance will be developed to provide the foundation for further enhancing the electrochemical performance and broadening the application field of WS2 materials.