核壳ZnFe2-xMxO4/C中空复合结构设计、调控及储锂性能研究

ZnFe2O4, as an intriguing anode for Li-ion batteries, demonstrates the unique advantages of high specific capacity, good safety and low cost. However, the modest electronic conductivity, low Coulombic efficiency (CE) and poor cycling performance greatly hinder its application in Li-ion power batteries. In the proposal, we controllably fabricated core-shell ZnFe2-xMxO4/C hollow hybrid anodes for advanced Li-ion batteries with the consideration of synergistic coupling effects of the hollow feature, Fe-site hetero-ion doping, and carbon coating in mind. Based on elegant combination of the experimental investigation and theoretical calculation, the influences of the Fe-site doping species、ratio upon the CE in first cycle, electric conductivity, working potential and structural stability were revealed accordingly. Furthermore, the immanent effects of the carbon structure and core-shell sur-/interface microstructures upon the significant enhancement in the whole electrochemical performance of the ZnFe2-xMxO4/C anodes were further demonstrated. The deep interaction among electrode microstructures, doping elements, phases and electrochemical Li-storage behavior was shed light upon herein. And the intrinsic relationship of component-microstructure-electrochemical Li-storage performance would be thus deduced. Technique supports and theoretical guidance were provided for the deep research and development of novel high-performance anodes with large capacity, good stability, high rates, high safety and cost-efficiency for next-generation Li-ion batteries.

ZnFe2O4作为锂离子电池负极材料具有高安全性、低成本和高比容量等独特优势。但较低电导率、库伦效率和较差循环稳定性等缺陷限制其在动力电池领域中的应用。基于此，本项目拟采用中空微结构、Fe位异离子掺杂和碳包覆三者协同耦合设计理念，可控合成高性能核壳ZnFe2-xMxO4/C中空结构锂离子电池复合负极材料。将实验研究和理论计算有机结合，探究Fe位掺杂组元及其比例对电极材料库伦效率、电子电导、嵌锂电压及结构稳定性的影响规律和作用机制，获知碳壳形态和核壳表-界面微结构对电极材料整体性能提升的内在机制，以及锂离子在碳壳及核壳表-界面中的输运机制。阐明脱嵌锂过程中电极微结构、掺杂组元、相组成与电化学储锂性能之间演变规律，构建“组分-微结构-电化学储锂性能”之间内在关系及作用理论。为开发具有高比容量、高稳定性、高倍率、高安全性和低成本的高性能新型锂离子电池负极材料提供技术支持和理论指导。

高安全性、低成本和高比容量使ZnFe2O4成为极有应用潜力的负极材料，但是其较低的电子电导性、库伦效率和较差的电化学稳定性等极大限制了它在动力电池领域中的广泛应用。鉴于此，本项目采用了中空微结构、Fe位离子掺杂及碳包覆三者协同耦合设计理念，可控合成了高性能核壳C/ZnMxFe2-xO4中空结构锂离子电池复合负极材料。将实验研究和理论计算有机结合，探究了Fe位掺杂组元及比例对材料库伦效率、电子电导、工作电压及结构稳定性的影响规律及作用机制，获知了碳层形态和核壳表-界面微结构对材料整体性能提高的内在机制及Li+在碳壳及核壳表-界面中的输运机制。阐明了脱嵌锂过程中电极微结构、掺杂组元、相组成与电化学储锂性能之间的演变规律，构建了“组分-微结构-电化学储锂性能”之间内在关系及作用理论。内外碳-碳/聚吡咯双导电和缓冲网络的创制为高效解决低电极电子电导/库伦效率/倍率和循环稳定性较差等难题提供了有效策略。理论模拟计算揭示了充放电过程中体积演变规律，为内部中空空腔体积的设计和调控提供了极为重要的指导，揭示了中空特征结构形成机制以及高效宏量和低成本可控合成策略，为拓展其产业化开辟新途径，促进相关学科的交叉融合。本项目的实施为开发具有高比容量、高稳定性、高倍率、高安全性、低成本的新型锂离子电池负极材料提供技术支持和理论指导。