多层中空碳硅纳米电缆阵列负极的可控制备及储锂性能研究

As the anode materials for Lithium ion batteries (LIB), Silicon (Si) exhibits the highest theoretical specific capacity. Unfortunately, the practical application of Si based anode has been impeded by its large volume expansion during lithiation processes, leading to worse rate capability and rapid capacity degradation during cycling. Besides, the reported self-supported Si based anode exhibited low areal capacities and specific capacities based on the mass of the whole electrode. Based on the problem mentioned above, we proposed to design and develop a multilayer hollow C@Si nanocables architecture on ultralight graphite foam to improve the lithium storage performance of the Si based anode. This novel self-supported anode will be fabricated by combining the technique of chemical vapor deposition, atomic layer deposition and wet chemical etching method. Moreover, in order to fabricate the multilayer hollow C@Si nanocables with different layer sizes and crystalline state, the effects of the experimental parameters on the morphology and microstructure of the nanocables will be systematic studied. The specific capacity, rate capabilities and capacity retention of the multilayer hollow C@Si nanocable array electrode will be measured by directly using them as self-supported LIB anodes. And the key factors that affecting their lithium storage performance will be systematic investigated as well. At last, the synergistic effect of the crystalline state and thickness of the C and Si layer will be established by combing the in situ and ex situ analytical technique, which will provide reliable experimental data and valuable technical solutions for the practical lithium ion battery application of Si based anodes.

作为锂离子电池负极材料，硅具有最高的理论比容量，但在锂化过程中存在巨大的体积膨胀，导致其具有极差的循环稳定性和倍率性能。此外，已报道的自支撑硅基负极具有较低的面积比容量和整体质量比容量，无法满足商业应用的要求。针对以上问题，本项目提出探索在超轻的泡沫石墨上构筑多层中空碳硅纳米电缆阵列，用以提升硅基负极的储锂性能。首先，拟结合化学气相沉积、原子层沉积和湿化学刻蚀技术实现多层中空碳硅纳米电缆阵列的制备；研究化学气相沉积和原子层沉积参数对纳米电缆形貌和微结构的影响，实现各层晶态、厚度的可控制备。然后，通过测试分析多层中空碳硅纳米电缆阵列电极作为锂离子电池自支撑负极的比容量、倍率性能和循环稳定性，深入研究影响其储锂性能的关键因素。最后，结合原位和外原分析技术，建立碳和硅的不同晶态及尺寸的相互协同作用机理，为硅基材料在锂离子电池中的应用提供可靠的实验数据和有价值的技术方案。

为了满足高速发展的新能源产业，迫切的需要发展一种可替代石墨负极的高容量材料作为下一代锂离子电池负极。然而，高容量负极材料在锂化过程中往往承受着更大的体积膨胀，这导致其无法同时具备高面积/体积比容量与稳定的循环性能。针对以上问题，本项目通过设计多种纳米导电框架对高容量负极的储锂性质进行优化：（1）制备了多层垂直碳纳米管阵列支撑的硅薄膜负极。所制备的电极在具有高面积/体积比容量（面积比容量>4 mAh/g，体积比容量大于4000 mAh/cm3）的同时保证了优异的循环和倍率性能（以840 mA/g电流密度下循环200圈后电极质量比容量超过1500 mAh/g）；（2）成功制备了导电纳米骨架支撑的多种锂离子电池复合材料，通过对其微观结构的精细调控并结合导电三维骨架与高容量负极材料的优势，得到了容量高，循环稳定和倍率性能优秀的锂离子电池负极；（3）发展了锂金属负极的制备工艺技术，通过在三维导电框架上进行亲锂性材料包覆获得了循环稳定性和倍率性能优秀的电极材料，并且进一步的通过非原位表征技术与有限元分析对其储锂机制进行研究。最终，项目负责人及团队围绕项目研究内容开展的工作，获得结果已在储能相关国际学术期刊发表标注SCI论文7篇，其中中科院一区论文4篇。