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纳米空洞加速富镍层状正极相转变的原位研究

李　爽*，李宇航，郑士建
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2025年 第44卷 第5期: 1000-6281（2025）05-552-07     下载地址：全文下载请到同方知网，万方数据库或重庆维普等数据库中下载！

纳米空洞加速富镍层状正极相转变的原位研究

李　爽*，李宇航，郑士建

（河北工业大学高性能轧辊材料与复合成形全国重点实验室，天津 300130）

摘　要　　富镍层状正极由于高放电比容量和高能量密度受到广泛关注，然而镍含量增加会加剧阳离子混排、晶格失氧、结构退化等问题，导致材料较差的热稳定性和快速的容量衰退。富镍正极材料在高温烧结过程中不可避免的会产生空位、层错甚至三维缺陷，而对于由初始缺陷导致的富镍正极衰退机理仍缺乏深入的研究。本文通过先进的原位透射电子显微技术，从原子尺度揭示了LiNi0.76Mn0.14Co0.1O2正极材料中存在的纳米空洞缺陷在加热条件下加速材料结构退化的现象。该空洞缺陷处在初始态表现为典型的层状相结构，但其中过渡金属元素比例降低，在加热过程中缺陷区域出现显著失氧，最先出现层状相向岩盐相的相变过程。空洞区域形成的岩盐相沿{003}面择优生长。本研究结果有助于深入理解合成过程形成的初始缺陷对富镍层状正极材料热稳定性和容量衰退的影响，对通过合成条件调控缺陷进而改善正极材料的性能具有指导意义。

关键词　　锂离子电池；富镍层状正极；透射电子显微镜；原位加热；相转变

中图分类号：TG11；TM911；TG115.21+5.3　　文献标识码：A Doi:10.3969/j.issn.1000-6281.2025.05.005

 

In-situ TEM study on nanovoids accelerating phase transition in Ni-rich layered cathode

LI Shuang*，LI Yuhang，ZHENG Shijian

(State Key Laboratory of High Performance Roll Materials and Composite Forming, Hebei University of Technology, Tianjin 300130, China)

Abstract　　Ni-rich layered cathodes have attracted considerable attention due to their high discharge specific capacity and elevated energy density. However, increasing the nickel content intensifies challenges such as cationic disordering, lattice oxygen loss, and structural degradation, which lead to poor thermal stability and rapid capacity decay. During high-temperature sintering, intrinsic defects, including vacancies, stacking faults, and even three-dimensional imperfections, are inevitably introduced into Ni-rich cathodes. The degradation mechanisms driven by these intrinsic defects remain poorly understood. In this work, advanced in-situ transmission electron microscopy was employed to reveal atomic-scale insights into structural degradation accelerated by nanoscale void defects in LiNi0.76Mn0.14Co0.10O2 cathodes under heating. These voids initially maintained a layered phase structure but exhibited reduced transition metal content. Upon heating, significant oxygen loss occurred in these void regions, triggering the earliest phase transformation from the layered to the rock-salt structure. The rock-salt phase formed within the voids preferentially grew along the {003} planes. These findings provide critical understanding of how synthesis-induced intrinsic defects deteriorate thermal stability and capacity retention in Ni-rich layered cathodes, offering practical guidance for optimizing synthesis conditions to regulate defects and enhance cathode performance.

Keywords　　lithium-ion battery; Ni-rich layered cathode; transmission electron microscopy; in-situ heating; phase transformation