由于高体积能量密度和独特的二维扩散通道，P2相Ni/Mn基氧化物正极材料在钾离子电池中备受关注。然而，深度充电状态下的P2→O2相变和晶格氧损失会造成电极结构的破坏和容量的衰减。本项目拟通过在过渡金属层中引入Na+、Mg2+、Al3+及其组合来调节过渡金属和氧的化学环境，进而调控过渡金属层间的静电排斥力和氧的电荷分布，从而消除不利相变并促进氧的可逆反应。本项目将运用X-射线衍射、球差校正透射电镜、循环伏安和恒电流充放电等技术来研究材料的结构组成和储钾性能。重点关注（1）掺杂离子的半径、价态、组合、含量、位置对材料的结构组成和电化学性能的影响，（2）循环过程中的电荷补偿机制和相转变机制，（3）电极在原子尺度下的结构演变和离子、电子的输运。阐明离子掺杂的改性机理、材料的储钾机制及构效关系，为钾离子电池和其他电池体系中高性能电极材料的设计提供理论基础和实验依据。

P2 phase Ni/Mn-based oxide cathode materials have attracted extensive attention in potassium-ion batteries due to their high volumetric energy densities and unique two-dimensional ion diffusion channels. However, the P2→O2 phase transition and lattice oxygen loss at the deeply charged states result in their structure degradation and capacity fading. This project is planning to suppress the undesirable structure evolution and promote reversible oxygen redox by introducing Na+, Mg2+, Al3+, and their combinations into the transition-metal layers. The doped cations can regulate the electrostatic repulsion between the transition-metal layers and the charge distribution of oxygen by adjusting the chemical environment of transition metal and oxygen. X-ray diffraction, scanning transmission electron microscopy equipped with a probe spherical aberration corrector, cyclic voltammetry, and galvanostatic charge/discharge etc. will be employed to investigate the structural compositions and K-storage performance of the as-synthesized materials. The project will be focused on (1) the effects of the radius, valence, combination, content, and position of the doped cations on the structural compositions and electrochemical performance, (2) the mechanisms of the charge compensation and phase transition during cycles, (3) the structure evolution as well as ion and electron transport at the atomic scale. The target of this project is to reveal the modification mechanism of the ion doping and the K-storage mechanism and structure-activity relationship of the electrode, and provide important insights into design of high-performance electrode materials for potassium-ion batteries and beyond.