新一代锂电池硅基负电极材料的优化和制备方法

Si is an attractive and promising anode material for lithium batteries, because it has a low discharge potential and the highest known therotical charge capacity. However, silicon anodes have limited application, because silicon's volume changes upon insertion and extraction of lithium, which results in pulverication and capacity fading. So how to increase capacity retention with battery cycling is one of the challenges associated with the use of high-capacity Si anodes. In this project, molecular modelling incorporating with numerical simulation,theoretical analysis and experimental study will be adopted. At first,the microscopical structure, dynamical transport properties and performance factors for the new porous composite Si-based anode will accurately identified by using of mathematical modelling and simulation. Furthermore, the effect of microscopical configration, morphostructure and lithiation phase on the transport of lithium-ion and battery performance will be comprehensively exploited. Moreover, the new theory and experimental approaches will be developed to disclose the new phonomon, law and interplay between controlling the microscopical structure and macroscpoic performances inside the novel porous composite Si-based anode. More importantly, we will provide insights into the key factors and microscopical mechanism on controlling the volumical and structurical changes upon the lithiation process and improving the transport of lithium-ion at the atomic level. Consequently, it is expected to realize rational desin of microscopical structure, accurate prediction of disired performance, simple, low-cost and efficienly fabrication of the exceptional electrode for rechargebile lithium batteries. We forsee that this preject may circumvent the present techenique bottoleneck， and offer the novel routes and therotical guidance for the large-scale application of Si-based anode.

锂电池新型负电极材料中，硅因其具有较低的电压平台和最高的理论电容而极具潜力和优势，是最有希望成为新一代高效锂电池负电极必选材料之一。但是，锂化中极高的体积效应所引起的活性材料粉化和电极失效，是硅基电极应用亟待解决的问题之一。本项目借用分子模拟、数值计算、理论分析和实验研究，表征新型多孔复合硅基材料的微观结构特性、动力传输特性和宏观性能参数；深入研究微观分子构形、结构形态、锂化相态对锂离子传输微观过程和电极性质的影响和协同规律；寻求新型复合硅基材料微观结构调控与宏观性能参数的内在关联；发展新理论及实验方法，探析新型多孔复合硅基电极材料内的新现象和新规律；从原子水平上，揭示控制锂化过程中体积和结构变化、强化锂离子传输过程的关键因素和机制。旨在实现优异硅基电极微观结构的理性化设计、性能的准确预测和简单高效制备，有效解决目前硅基材料推广应用的技术瓶颈，并为促进其大规模应用提供理论指导和新途

锂电池新型负电极材料中，硅因其具有较低的电压平台和最高的理论电容而极具潜力和优势，是最有希望成为新一代高效锂电池负电极必选材料之一。但是，锂化中极高的体积效应所引起的活性材料粉化和电极失效，是硅基电极应用亟待解决的问题之一。本项目借用分子模拟、数值计算、理论分析和实验研究，表征了新型多孔复合硅基材料的微观结构特性、动力传输特性和宏观性能参数；从原子和量子水平，深入分析了硅基电极的微观构形、结构形态、锂化的微观过程、铜硅的界面结合机理，获得了控制锂化过程中体积和结构变化、强化锂离子传输过程的关键因素和机制。利用数值模拟方法，分析了冷喷涂中送粉气流对喷管中气固两相流流动形态、动量和能量交换以及颗粒沉积特性的影响，得出送粉气流的相关参数实际上在很大程度上制约着喷涂效果的结论，引起了人们对送粉气流的关注；通过引入形状因子分析了块状硅粒与球形金属颗粒沉积特性的不同，获得了块状颗粒的沉积过程中喷涂参数调控规律和最佳喷涂效果时所对应的颗粒形状。利用气体动力喷涂技术成功地将活性材料微米级硅颗粒喷涂在作为集电器的铜箔上；通过沉积形貌和质量变化的观测，发现了硅沉积铜后质量减小的特有现象及其原因；并通过单颗硅颗粒沉积，探明了铜硅间铜基的绝热剪切失稳和颗粒间机械咬合的结合机理。综合各个尺度上硅颗粒在铜箔上沉积的研究，探明了硅铜之间特有的结合机制以及硅基材料微观结构调控与宏观性能参数的内在关联。最终实现了优异硅基电极微观结构的理性化设计、性能的准确预测和简单高效制备，有效解决目前硅基材料推广应用的技术瓶颈，并为促进其大规模应用提供理论指导和新途径。