细菌纤维素为前驱体调控硬碳负极材料的特定孔结构及其储钠行为研究

Sodium-ion battery is considered as the most possible alternative to lithium-ion battery to be the next ideal battery for large-scale energy storage equipment, because of its advantages of abundant resource and low cost. However, low energy density is the technological bottleneck for the development and application of sodium-ion battery. Aiming at the problem, this proposal put forward two specific parameters of porosity and tortuosity of hard carbon materials to improve the rate of insertion-extraction and the storage capacity of sodium ions, further enhance the energy density of sodium-ion battery. The main content of this project is as follows: design and culture ordered porous bacterial cellulose, which is further used as precursor for preparing the anode materials. The values of porosity and tortuosity of carbon are mediated through varying the condition of bacterial cultures to construct the pore system for effective diffusion and insertion-extraction of sodium ions. The key scientific problem of this project is the relationship of porosity and tortuosity, and their effects on the mechanism of energy storage behavior of sodium-ion battery. Through studying this scientific problem, we would construct the rational pore structure with matching porosity with tortuosity for anode materials. And thus the energy density of sodium-ion battery would finally be enhanced.

钠离子电池由于钠资源丰富、成本低廉，被认为是最有可能取代锂离子电池成为大规模储能装置的理想电池，但是能量密度低是限制其开发和应用的技术瓶颈。针对这一问题，本项目创新性地提出通过调控硬碳材料的特定孔结构参数——孔隙率和曲折率来提高钠离子的脱嵌速率和储存容量，进一步提升钠离子电池的能量密度。主要研究内容是设计和培养具有有序多孔结构的细菌纤维素，并以其为前驱体制备硬碳负极电极材料；改变细菌纤维素的发酵培养基及培养条件，调控硬碳材料的孔隙率和曲折率，构筑有利于钠离子有效扩散、脱嵌的孔道结构。研究孔隙率和曲折率之间的关系、以及二者对钠离子电池电化学储能行为的影响机制的科学问题，预计将构筑孔隙率和曲折率相匹配、具有合理孔道结构的硬碳负极电极材料，制备高能量密度的钠离子电池。

钠离子电池由于钠资源丰富、成本低廉，被认为是最有可能取代锂离子电池成为大规模储能装置的理想电池，但是能量密度低是限制其开发和应用的技术瓶颈。针对这一问题，本项目提出通过调控硬碳材料的特定孔结构参数来提高钠离子的脱嵌速率和储存容量，进一步提升钠离子电池的能量密度。主要研究内容是设计和制备具有有序多孔结构的细菌纤维素，并以其为前驱体制备硬碳负极电极材料；改变细菌纤维素的预处理工艺条件，调控硬碳材料的孔结构，构筑有利于钠离子有效扩散、脱嵌的孔道结构。采用自由基聚合的方法，在细菌纤维素上原位聚合聚甲基丙烯酸甲酯，通过调控单体量和改变碳化温度，优化硬碳材料的碳层间距和微孔结构。通过研究孔道结构之间的关系、以及对钠离子电池电化学储能行为的影响机制的科学问题，构筑具有合理孔道结构的硬碳负极电极材料。通过扩大硬碳材料的碳层间距和调控硬碳材料的孔结构，分别提升了硬碳负极的平台容量和斜坡容量，增加了首放效率的同时提高了电极的能量密度。制备的碳负极材料在0.01-2.5 V电压区间内，电流密度为0.03 A g-1和1 A g-1时，比容量可达到323.6 mAh g-1和134.47 mAh g-1，首放效率提高到82.8 %。