氢化反应制备轻金属硅化物的反应机理及其结构和电化学性能

项目名称： 氢化反应制备轻金属硅化物的反应机理及其结构和电化学性能

项目编号： No.51471152

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 一般工业技术

项目作者： 刘永锋

作者单位： 浙江大学

项目金额： 80万元

中文摘要： 开发新型高容量储锂材料是进一步提高锂离子电池能量密度的关键技术之一。Si基材料具有高达4200 mAh/g的电化学储锂容量，被认为是最有发展前景的锂离子电池阳极材料之一，但其在嵌/脱锂过程中巨大的体积膨胀极易引起材料粉化、破裂，从而导致循环稳定性极差。合金化是改善Si基锂离子电池阳极材料性能的有效手段之一，但金属硅化物组成元素间巨大的熔点差异导致其合成困难，产物纯度较低。本项目针对这一问题，提出用金属氢化物或配位氢化物替代纯金属，通过氢化反应技术制备高纯度的IA-IIIA族金属硅化物，揭示氢化反应机理；系统研究材料的成分、结构和形貌与电化学储锂行为的关系，掌握材料在嵌/脱锂过程中的成分、结构和形貌变化规律，揭示材料的电化学储锂机理和循环容量衰退机制，并通过尺寸控制和原位碳包覆进一步改善材料的电化学储锂性能，为发展新一代高能量密度锂离子电池奠定基础。

中文关键词： 储氢材料；氢化反应；金属硅化物；电化学性能；结构

英文摘要： Developing new-type lithium storage materials with high-capacity is one of the key techniques to further enhance the energy densities of Li-ion batteries. Si-based materials have been regarded as one of the most promising anode materials of Li-ion batteries due to their high capacity of 4200 mAh/g. However, the huge volume change during lithiation/delithiation leads to severe particle pulverization and fracture, consequently resulting in quite poor cycling stability. Alloying with other active/inactive elements is one of the effective approaches to improve the electrochemical lithium storage properties of Si-based anode materials of Li-ion batteries. However, it is rather difficult to prepare the high-purity metal silicides due to the big discrepancy between the melting points of Si and other constituent elements. To solve this problem, this project proposes a novel approach of hydrogen-driven chemical reaction (HDCR) to prepare Group IA-IIIA metal silicides. By replacing pure metals with the corresponding metal hydrides or complex hydrides, the new-type high-purity light metal silicides are able to be successfully synthesized. The mechanisms of HDCR will be revealed. The relationship between compositions, structures, morphologies and electrochemical lithium storage properties of materials will be studied. The change rules of compositions, structures and morphologies of materials during lithiation/delithiation will be elucidated. The mechanisms of electrochemical lithium storage and capacity degradation will be understood. Moreover, the lithium storage properties will be further improved by the size controlling and in-situ carbon coating. As a result, we hope that it can bottom the development of the next generation Li-ion batteries with high energy densities.

英文关键词： Hydrogen storage materials;Hydrogen-drived chemical reaction;metal silicides;electrochemical properties;structure