Real-world industry-relevant battery composite electrodes are hierarchically structured. In particular for active cathode particles, there is a consensus that their structural and chemical defects could have a profound impact on battery performance. An in-depth understanding of the underlying mechanisms could critically inform cathode material engineering, which remains a daunting challenge at present. Herein, we tackle this question by studying LiCoO₂ (LCO) with trace doping of Ti, which exhibits low solubility in the LCO-layered lattice. We observed the spontaneous and heterogeneous segregation of the dopant (Ti), which modified the particle surface and the buried grain boundaries while inducing a significant amount of lattice distortions. These multiscale structural defects promote the robustness of the LCO lattice at a deeply charged state (above 4.5 V). Our result formulates a multiscale defect-engineering strategy that could be applicable to the synthesis of a broad range of energy materials.

现实世界中与行业相关的电池复合电极是分层结构的。特别是对于活性阴极颗粒，人们一致认为它们的结构和化学缺陷可能对电池性能产生深远影响。对潜在机理的深入了解可能会为阴极材料工程学提供关键信息，这目前仍是一项艰巨的挑战。在这里，我们通过研究LiCoO ₂解决了这个问题（LCO）与痕量的Ti掺杂，在LCO层状晶格中表现出低溶解度。我们观察到了掺杂剂（Ti）的自发性和非均质性偏析，它修饰了粒子表面和掩埋的晶界，同时引起了大量的晶格畸变。这些多尺度的结构缺陷促进了LCO晶格在深度充电状态（高于4.5 V）下的坚固性。我们的研究结果制定了一种多尺度缺陷工程策略，可应用于多种能源材料的合成。