多级Na2Ti3O7@MXenes/C复合材料原位构建、表界面调控及其储钠机制

Owing to smart intergration of high energy density by Na-ion batteries and high power density of electrical double-layer capacitors, Na-ion supercapacitors (NISs) have been becoming one of the researching hotspots worldwide. Considering poor kinetic match between negative and positive electrodes, we herein proposed an in situ one-step microwave synthesis of high-capacity Na+-insertion Na2Ti3O7@MXenes/C anodes with good electronic conductivity, stable sur-/interfaces, hierarchical porosity, and superior kinetics. Promising electrochemical properties including high power rate, large reversible energy density and long-span life were expected via electrode component/composition optimization, microstructure design, and sur-/interface property regulation. According to the in-situ/ex-situ characterizations, theoretical modeling and mathematical simulation, and eletrochemical techniques/devices, general strategies to optimize electrode/electrolyte components, and formation mechanism of microstructures were detailedly revealed on multi-scale levels. New insights into the electrode-electrolyte sur-/interfacial charge transfer, and intrinsic Na+-storage mechanisms were presented. The underlying relationship and interaction theory between electrode and electrolyte composition/component, sur-/interface properties, and electrochemical Na+-storage performance were rationally established. Finally, new understandings and fundamental guidance were provided for further design, controllable fabrication and practical applications of high-performance NISs electrodes and systems with high energy and power densities.

由于兼顾钠离子电池高比能量和双电层电容器高比功率优势，新型钠离子电容器成为目前储能领域研究重点之一。针对钠离子电容器正负极储荷动力学不匹配关键问题，在前期研究之上，本项目拟采用一步微波合成策略高效原位可控构建具有高电子电导、稳定表界面、分级孔和动力性能优异的高比容量Na2Ti3O7@MXenes/C嵌钠负极材料。通过电极组分优化、微结构设计和表界面性质调控来实现Na2Ti3O7@MXenes/C多级微纳电极高比功率、高可逆比容量和长循环寿命。基于（非）原位表征技术、模拟计算及系统电化学技术/装置，多层次水平阐释微纳电极/电解液组分优化共性策略、微结构形成及调控机制，阐明电极−电解质表界面传荷过程及储钠新机制，发展并建立电极/电解液组分、微结构、表界面特性−储钠性能间本质构效关系及耦合作用理论，构建钠离子电容器，为高性能钠离子电容器电极材料及储钠体系设计、构筑和应用开发提供新思路和科学依据。

由于兼顾钠离子电池高比能量和双电层电容器高比功率固有优势，新型钠离子电容器成为了当下电化学储能领域研究热点和重点之一。针对钠离子电容器正、负极储荷动力学不匹配关键问题，本项目采用了一步微波合成策略高效原位可控构建具有高电子电导、稳定表界面、分级孔和动力性能优异的高比容量Na2Ti3O7@MXenes/C嵌钠负极材料。其中，无序碳材料（C）作为“电子导线”均匀分布于二维导电相MXenes，高电活性的纳尺度NTO 原位“寄生”于全贯通导电网络MXenes/C 表面和层间。并通过电极组分优化、微结构设计和表界面性质调控实现了Na2Ti3O7@MXenes/C多级微纳电极高比功率、高可逆比容量和长循环寿命。并基于（非）原位表征技术、模拟计算及系统电化学技术/装置，多层次水平阐释了微纳电极/电解液组分优化共性策略、微结构形成及调控机制，阐明了电极−电解质表界面传荷过程及储钠新机制，发展并建立了电极/电解液组分、微结构（电子结构、活性表界面和多级孔道等）、表界面特性−电化学储钠性能间本质构效关系及耦合作用理论，构建了钠离子电容器。最终，通过电极/电解液组分调控、微结构设计、表界面优化及理论模拟计算，解决了其中理论和设计等问题，为高性能钠离子电容器负极材料及高比能和高比功率电化学储钠体系设计、构筑及应用开发提供了新思路和科学依据。