新型锂离子电池负极材料Li3VO4一维复合纳米结构的可控制备及其储锂性能、机制研究

Anode materials in lithium ion batteries, based on intercala- tion/deintercalation reactions, have attacted much attention, due to their good structure stability, small volume variation, outstanding cycling stability and rate capability. However, there are only a few anode materials based on this mechanism. Furthermore, they have serious issues in terms of working voltage, discharge capacity, volumetric energy density or system safety. Thus, it is highly desired to develop novel anode materials based on intercalation/deintercalation reactions. Here, Li3VO4 in this proposal can effectively address the above concerns. One- dimensional Li3VO4 nanomaterials assemble many advantages like nanoscale size, one-dimensional shape, surface coating plus with proper doping within one particle, making them a promising candidate for lithium ion batteries. We are going to synthesize one-dimensional Li3VO4 nanomaterials by a low-temperature wet-chemistry approach followed with a high-temperature annealing process. Then, their lithium- storage performances will be measured and compared with reported Li3VO4 or home-made ones in other shapes to clarify structure effect and surface effect on electro- chemical performances. Finally, the lithium-storage mechanism in Li3VO4 is carefully investigated by in-situ/ex-situ structure and component characterization, electrochemical measurements,theoretical simulation, etc. to disclose the evolution of anode materials during discharge/charge processes.

基于脱嵌储锂机制的锂离子电池负极材料，在充放电过程中，因其结构稳定，体积效应小，有利于增加反应可逆性，提高循环和倍率性能，所以引起广泛的关注。但是目前可供选择的该类型负极材料种类很少，而且在工作电压、储锂容量、能量密度或者体系安全等方面存在明显问题，因此有必要研发新型脱嵌储锂的负极材料。本项目所选择的Li3VO4可以有效地避免已有材料的上述问题，因此我们将利用低温液相合成技术结合高温煅烧制备Li3VO4的纳米材料，通过尺寸控制、表面包覆和结构掺杂等途径，降低充放电过程中的结构应力，提高电荷输运性能，改善锂离子电池的循环和倍率性能；结合原位/异位结构分析、电化学测试结果和理论计算，探讨脱嵌储锂的反应过程，为结构设计、表面包覆和理性合成提供指导。

基于脱嵌储锂机制的锂离子电池负极材料，在充放电过程中，因其结构稳定， 体积效应小，有利于增加反应可逆性，提高循环和倍率性能，所以引起广泛的关注。但是目前可供选择的该类型负极材料种类很少，而且在工作电压、储锂容量、能量密度或者体系安全等方面存在明显问题，因此有必要研发新型脱嵌储锂的负极材料。在本项目资助下，我们利用低温液相合成技术结合高温处理过程，成功地制备出多种钒酸锂及其相关化合物的锂离子电池负极材料，并对其电化学性能进行了细致的研究和分析。主要成果包括：使用三聚氰胺和柠檬酸为原料，成功地制备出钒酸锂/氮掺杂的碳基复合纳米材料，其电化学获得显著的改善和提升；首次报道表面缺陷能够有效地降低电荷传递电阻，从而降低钒酸锂的电极极化并提升质量比容量。重要的是，该方法无需复杂纳米结构和精准的粒径控制，就能实现电化学性能改进和提升；依据钒酸锂倍率性能优异的特点，率先对于其在锂离子电容器的应用进行了有益的尝试，这对于今后扩宽其他类似电极材料的应用具有重要借鉴意义；使用导电高分子和多壁碳纳米管增强钒系硫化物的导电性，从而实现其电化学性能的提高。研究成果分别发表在Angew. Chem. Int. Ed., Adv. Mater., Adv. Funct. Mater., ACS Nano, Nano Energy, Adv. Sci.等知名期刊上，多篇研究论文被评选为高引用论文（ISI Highly Cited Papers）或者是热点论文（Hot papers）。