Microstrain and the associated surface-to-bulk propagation of structural defects are known to be major roadblocks to developing high-energy and long-life batteries. However, the origin and effects of microstrain during the synthesis of battery materials remain largely unknown. Here we perform microstrain screening during real-time and realistic synthesis of sodium layered oxide cathodes. Evidence gathered from multiscale in situ synchrotron X-ray diffraction and microscopy characterization collectively reveals that the spatial distribution of transition metals within individual precursor particles strongly governs the nanoscale phase transformation, local charge heterogeneity and accumulation of microstrain during synthesis. This unexpected dominance of transition metals results in a counterintuitive outward propagation of defect nucleation and growth. These insights direct a more rational synthesis route to reduce the microstrain and crystallographic defects within the bulk lattice, leading to significantly improved structural stability. The present work on microstrain screening represents a critical step towards synthesis-by-design of defect-less battery materials.

众所周知，微应变和相关的结构缺陷的表面到本体传播是开发高能和长寿命电池的主要障碍。然而，电池材料合成过程中微应变的起源和影响在很大程度上仍然未知。在这里，我们在钠层状氧化物阴极的实时和真实合成过程中进行微应变筛选。从多尺度原位同步加速器 X 射线衍射和显微镜表征中收集的证据共同表明，单个前驱体颗粒内过渡金属的空间分布强烈控制了合成过程中纳米级相变、局部电荷异质性和微应变的积累。过渡金属的这种意想不到的优势导致了缺陷成核和生长的反直觉向外传播。这些见解指导了一条更合理的合成路线，以减少体晶格内的微应变和晶体学缺陷，从而显着提高结构稳定性。目前的微应变筛选工作代表了朝着无缺陷电池材料的综合设计迈出的关键一步。