Limitations in electrochemical performance as well as supply chain challenges have rendered positive electrode materials a critical bottleneck for Li-ion batteries. State-of-the-art Li-ion batteries fall short of accessing theoretical capacities. As such, there is intense interest in the design of strategies that enable the more effective utilization of active intercalation materials. Pre-intercalation with alkali-metal ions has attracted interest as a means of accessing higher reversible capacity and improved rate performance. However, the structural basis for improvements in electrochemical performance remains mostly unexplored. Here we use topochemical single-crystal-to-single-crystal transformations in a tunnel-structured ζ-V₂O₅ positive electrode to illustrate the effect of pre-intercalation in modifying the host lattice and altering diffusion pathways. Furthermore, operando synchrotron X-ray diffraction is used to map Li-ion site preferences and occupancies as a function of the depth of discharge in pre-intercalated materials. Na- and K-ion intercalation ‘props open’ the one-dimensional tunnel, reduces electrostatic repulsions between inserted Li ions and entirely modifies diffusion pathways, enabling orders of magnitude higher Li-ion diffusivities and accessing higher capacities. Deciphering the atomistic origins of improved performance in pre-intercalated materials on the basis of single-crystal-to-single-crystal topochemical transformation and operando diffraction studies paves the way to site-selective modification approaches for positive electrode design.

电化学性能的限制以及供应链的挑战使正极材料成为锂离子电池的关键瓶颈。最先进的锂离子电池无法达到理论容量。因此，人们对设计能够更有效地利用活性插层材料的策略产生了浓厚的兴趣。碱金属离子的预嵌入作为获得更高可逆容量和改善倍率性能的一种手段引起了人们的兴趣。然而，改善电化学性能的结构基础仍未被探索。在这里，我们在隧道结构的 z-V ₂ O ₅正极中使用拓扑化学单晶到单晶的转变来说明预插层在修改主晶格和改变扩散路径中的效果。此外，操作同步加速器 X 射线衍射用于绘制锂离子位点偏好和占用率与预插层材料中放电深度的函数关系。钠离子和钾离子嵌入“支撑打开”一维隧道，减少插入的锂离子之间的静电排斥，并完全改变扩散路径，使锂离子扩散率提高几个数量级并获得更高的容量。基于单晶到单晶拓扑化学转变和原位衍射研究破译预插层材料性能改进的原子起源，为正极设计的位点选择性修饰方法铺平了道路。