基于磁性测试揭示CoO储锂机理

CoO lithium storage mechanism revealed based on magnetic measurement

当今社会对储能技术需求日益迫切,电化学储能作为储能系统中的“桥梁”极具发展潜力,然而面临电化学储能中微量杂质相检测以及复杂界面储能探测的挑战,传统表征手段已经显示出局限性。储能材料的晶体结构、元素价态、电子能带以及电化学特性与其磁学性质密切耦合,因此本文基于磁性测试,通过高低温等温磁化曲线(magnetic hysteresis,M-H)测试、零场冷/场冷(zero-field-cooled/field-cooled,ZFC/FC)变温磁化曲线测试,相较于传统表征手段X射线衍射(X-ray diffraction,XRD)、X射线光电子能谱(X-ray photoelectron spectroscopy,XPS)及高分辨透射电镜(high resolution transmission electron microscope,HRTEM),能够定量、高效、精准地检测出CoO中存在有效降低极化、提升首圈库仑效率(74.3%~83.77%)、提高大电流循环性能(2 A/g 50圈容量保持率116.59%)的微量金属Co杂质相(CoO/Co@20min 0.66%,CoO/Co@40min 2.27%)。同时本文利用原位实时磁学循环伏安法CV测试及恒流充放电测试,直观揭示出CoO在低电压区间里复杂、难以探测的空间电荷与固体电解质界面(solid electrolyte interphase,SEI)膜两种不同类型的界面储能机制,成功解释了CoO远超理论容量的额外容量来源。储能材料的合成制备离不开高度精准的杂质相检测,储能领域的下一步研究发展取决于能否对界面储能深入理解。本工作为杂质相检测及界面储能机理探测提供了一种无伤且高分辨的磁学全新视角,为推动储能领域的创新,解决当今社会面临的能源挑战贡献力量。

The increasing demand for energy storage technology highlights electrochemical energy storage as a crucial component of energy storage systems.However,conventional characterization techniques encounter difficulties discerning subtle impurity phases and exploring intricate energy storage processes at interfaces.The magnetic properties of energy storage materials,which are intricately linked with crystal structures,elemental valence states,electronic energy bands,and electrochemical properties,offer a promising avenue for exploration.This paper uses magnetic hysteresis(M-H)tests and zero-field-cooled/field-cooled(ZFC/FC)tests to elucidate the lithium storage mechanism of CoO.A comparative analysis is conducted using traditional characterization methods,including x-ray diffraction,x-ray photoelectron spectroscopy,and high-resolution transmission electron microscopy(HRTEM).Our findings reveal trace amounts of metallic Co monomer impurity phases in CoO with remarkable precision(CoO/Co@20min 0.66%,CoO/Co@40min 2.27%).These impurity phases play a crucial role in reducing polarization,enhancing the first-cycle Coulombic efficiency(74.3%—83.77%),and improving high-current cycling performance(2 A/g 50-cycles capacity retention of 116.59%).Moreover,this study employs in-situ real-time magnetic cyclic voltammetry tests and constant-current charge/discharge tests to visually elucidate the intricate interfacial energy storage mechanism between the space charge and the solid electrolyte interphase membrane of CoO in the low-voltage zone.The results successfully explain the origin of the extra capacity of CoO,surpassing the theoretical capacity.The synthesis and formulation of energy storage materials are intricately tied to achieving precision in impurity phase detection.Our work offers a novel perspective on using magnetism for detecting impurity phases and probing energy storage mechanisms at interfaces in a noninvasive and high-resolution manner.This contribution propels innovations in the field of energy storage,addressing contemporary energy challenges faced by society.The evolution of research and development endeavors in energy storage relies on a profound understanding of the intricate intricacies governing interfacial energy storage phenomena.