碳包覆Mn-Fe-F三元纳米复合结构材料的设计、合成，以及锂电正极应用

High-energy cathode materials based on fluorides are increasingly investigated for energy storage recently. To deal with the poor conductivity and large hysteresis of fluorides, this project plans to synthesize novel carbon encapsulated Mn-Fe-F ternary hybrid nanomaterials which will regulate the energy band structure and improve the conductivity and hysteresis through adjusting the content of metals and selective carbon encapsulation. The main content is listed as follows: (1) confirm selective Fe/Mn ratios base on density functional theory. Through adjusting the content of Mn or Fe, the energy band structure of Mn-Fe-F ternary hybrid nanomaterials will be regulated for dealing with the mentioned issues as poor electron and ion conductivity and large hysteresis; (2) synthesize those Mn-Fe-F hybrid nanostructures by combining techniques of in-situ topochemical conversion and atomic layer deposition and discuss the influence of Fe/Mn ratios on the Mn-Fe-F hybrid structure; (3) fabricate novel hybrid nanomaterials of fluorides as micro/nano carbon bubbles supporting Mn-Fe-F ternary nanocrystals, ACMK-3 and carbon nanotubes encapsulated Mn-Fe-F nanocrystals and analyze the further insights into the influences of metal atom doping and carbon coupling on the mechanism and electrochemical property in lithium storage; (4) exert those Mn-Fe-F ternary hybrid nanomaterials on the application of cathode materials for lithium ion batteries.

近年来，设计氟化物高能锂电正极材料在储能领域受到普遍关注。本项目拟合成新型碳包覆Mn-Fe-F三元纳米复合结构材料，通过调节不同尺寸金属离子的含量及有选择性碳包覆来实现对氟化物能带结构的调控，同时解决氟化物导电性差，滞后严重等问题。主要内容包括：(1) 基于理论计算，寻找合适的Mn-Fe-F配比。通过改变Mn或Fe的含量来调节其能带结构，以期改善其导电能力，滞后严重等问题；(2) 结合原位拓扑转换反应及原子层沉积等手段合成特定结构Mn-Fe-F复合材料。探讨Fe/Mn比对氟化物复合结构的影响；(3)以Mn-Fe-F纳米结构为基础合成碳纳米/微米泡负载Mn-Fe-F三元纳米晶、Mn-Fe-F纳米晶填充的有序结构碳和非晶碳管等氟化物纳米复合结构材料，深入分析金属掺杂及快动力学载体耦合对三元氟化物储锂机理及电化学性能的影响；(4)拓展三元Mn-Fe-F基氟化物在锂电正极领域的应用。

电极材料电化学特性与表界面、晶粒尺度、缺陷、形貌等微结构息息相关。为解决传统过渡金属化合物储锂稳定性差、利用率低、储锂容量有限等问题，本项目从表/界面工程、结构缺陷设计，及微结构和尺度控制等方面综合考虑，利用表界面限域效应合成系列过渡金属氧化物超小纳米晶、利用ZnO表面原位亚埃级有机表界面抑制SEI形成、利用表界面掺杂提高Cu2O纳米晶中空位浓度、利用空位诱导双金属碳化物晶粒局域析晶、利用局域纳米畴诱导块体有机金属微结构演化等，有效解决诸如过渡金属氧化物库伦首效低、双金属碳化物储锂和惰性金属颗粒储能活性位点有限，MOF块体储能特性差，以及它们循环特性衰退明显等棘手问题。.另外，引入“形貌重塑”的概念，用于构筑高密储锂电极，实现电极在体积容量密度、循环稳定性、倍率特性，和长寿命的有机结合。