高能量密度锂-硫电池电极的设计、制备及其性能研究

Due to the lower specific capacity of the traditional cathode materials, the energy densities of the commercial lithium-ion batteries are small. In order to meet the needs of longer-range electric vehicles, it is necessary to develop the new-generation power batteries. Lithium-sulfur battery is a potential candidate owing to its high energy density.. Devoting to solve the problems of the low coulombic efficiency, rapid capacity fade, poor cycle life and safety hazard for current lithium-sulfur batteries, the present project plans to design and fabricate the electrodes of silicon/carbon and sulfur/carbon composite nanofibers, and systematically investigate their application in lithium-sulfur batteries. We intend to prepare the composite nanofibers and porous carbon nanofibers with controllable diameters, lengths, structures and compositions using a low-cost and high-efficiency electrostatic spinning technique followed by some post-treatment processes, and try to find out effective approaches to improve the electrochemical performances of silicon and sulfur, prevent the dissolution of polysulfides in electrolyte, and suppress the shuttle effect. With the optimized lithiated-silicon/carbon nanofibers anode and the sulfur/carbon nanofibers cathode, we expect to assemble a prototype device of lithiated silicon-sulfur battery with a energy density higher than 500 Wh/kg, a cycle life longer than 500 times, and a capacity retention larger than 80%. The project implemention will provide reliable basic experimental data and valuable technical solutions for developing lithium-sulfur batteries with high energy density, long cycle life and good safety.

受传统正极材料自身储锂容量的限制，锂离子电池的实际能量密度较低。为满足电动汽车发展的要求，需要发展新一代的动力电池体系。具有高能量密度的锂-硫电池颇具发展潜力。. 致力于解决锂-硫电池库伦效率低、容量衰减快、循环寿命短以及采用金属锂负极所存在的安全隐患问题，本项目拟在纳米尺度上设计和制备硅/碳、硫/碳复合纤维电极，系统研究它们在锂-硫电池中的应用。拟采用高效率的电纺丝技术并结合后处理工艺，制备出直径、长度、结构和成分可控的硅/碳、硫/碳和碳多孔纳米纤维，提出改善硅和硫的电化学特性、阻止多硫化锂在电解液中溶解、抑制“飞梭”效应的有效途径。以优化制备的锂化硅/碳负极、硫/碳正极组装出能量密度≥500 Wh/kg、循环次数≥500次、容量保持率＞80%的锂-硫电池原型器件。项目的实施将为能量密度高、循环寿命长、安全性好的锂-硫电池的研发提供可靠的基础实验数据和有价值的技术方案。

本项目以研发能量密度高、循环寿命长、安全性好的锂硫电池为目标，致力于解决传统锂硫电池库伦效率低、容量衰减快、循环寿命短以及金属锂负极所存在的安全隐患等问题。通过引入了多种纳米吸附剂和催化剂，提出了阻止多硫化锂在电解液中的溶解、抑制多硫化锂穿梭效应、加速电极氧化还原反应的有效途径；在纳米尺度上设计出具有优异电化学性能的锂硫电池的电极和隔膜，获得了最佳的制备技术路线和工艺参数；采用多种电化学评价技术，并结合原位X射线衍射实时测量，表征了电极、隔膜以及电池整体的电化学特性，探讨了其中的电化学反应机理；系统研究了所制备的电极、隔膜在锂硫电池中的应用，以优化制备的电极、隔膜组装出了高性能的锂硫电池原型器件；在国际学术刊物上发表标注有本研究项目资助的研究论文共计31篇。所获成果为高性能锂硫电池的研发积累了可靠的基础实验数据，提供了有价值的技术方案，将在推动锂硫电池走向更广泛的应用领域发挥作用。