多元协同掺杂与复合化调控NASICON型AxTi2(PO4)3的储钾特性

钾离子电池是极具研究价值与应用前景的新型二次电池，负极材料是其研究重点与应用瓶颈。钠快离子导体AxTi2(PO4)3(ATP)结构稳定，具有独特三维离子传输通道，有望实现K+快速且稳定嵌脱。但ATP中TiO6八面体被PO4基团分隔，导电性及倍率性能较差，且其储K机制基于Ti4+/Ti3+与Ti3+/Ti2+价态转换，比容量受限。本项目拟设计合成多元离子掺杂ATP复合材料，构筑多级微纳结构实现电子/离子快速迁移，利用赝电容效应提高其比容量与倍率性能；通过多元协同掺杂调节材料晶体结构，减小带隙、提高本征电子电导、调控充放电电位；利用碳复合构建三维电子导电网络，并与高容量材料复合提高储钾容量。运用材料表征及电化学测量技术，结合第一性原理计算，研究多元协同掺杂与复合对其性能的影响，探索储钾机理及复合组分间的性能耦合机制，揭示材料构性关系。本项目将为ATP材料在钾离子电池中的应用提供理论与实验基础。

Potassium ion batteries(KIBs) are promising novel secondary batteries with important research value. However, there remains a big challenge to develop high-performance anode materials for KIBs. AxTi2(PO4)3(ATP) has stable structure with unique 3D paths for ions diffusion and could realize the fast and stable insertion/deinsertion of K+. Thus, it is considered as one of promising anode materials for KIBs. However, the octahedral TiO6 are separated by the PO4 in its crystal structure, so it suffers from poor conductivity and worse rate capability. Besides, its potassium-storage mechanism is mainly based on the redox reaction of Ti4+/Ti3+ and Ti3+/Ti2+, so the specific capacity is limited. In this proposal, ATP composite with micro/nanostructures will be designed and synthesized. The micro/nanostructures are beneficial to ions/electrons diffusions and could bring pseudocapacitance effect, which favors specific capacity and rate capability. Multi-elements co-doping is utilized to adjust the electronic structure, change the band gap, improve the electronic conductivity, and control the working potential. Besides compositing with carbon, ATP is compounded with high-capacity materials to improve its specific capacity. Material characterizations and electrochemical measurements, combined with first principle calculation are used to investigate the multi-elements co-doping effects, the potassium storage mechanism of ATP composites, as well as the synergistic effects between ATP, carbon, and high-capacity components. This project will provide a theoretical and technical basis for ATP as anode materials for potassium ion batteries.