In situ defect characterization of LiFePO4 cathodes with positron annihilation spectroscopy PAS

利用正电子湮没光谱 PAS 对 LiFePO4 阴极进行原位缺陷表征

• 批准号: 318160244
• 负责人: Professor Dr. John Banhart
• 金额: --
• 依托单位: Fachgebiet Struktur und Eigenschaften von Materialien
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/318160244?language=en
• 关键词: situ; defect; characterization; LiFePO4; cathodes

Today lithium ion batteries (LIB) are one of the most promising candidates for energy storage. The aim of this project is to get further insight into the generation of defects and their properties in cathodes during cycling. The positron annihilation spectroscopy (PAS) is used to establish the technique as analyzing tool for in situ defect characterization of LIBs. The investigation focusses on LiFePO4 as cathode material.Based on the highly used Swagelok type cell system the design of an in situ cell is intended which will satisfy both the requirements to PAS-Method and to battery technology. The objective is to observe the cathode processes on atomic scale during cycling. The focus is on the behavior of defects like lattice vacancies or boundaries due to phase changes. Understanding and optimizing the ongoing processes in the cathode material is the objective. Dynamic PALS measurements with previously unrealized time resolution were developed by the proposer (Banhart, 2011) and will be employed here.The investigation of material parameters in respect to the PAS signal is substantial for the use of the PAS-technique in the field of LIB-technology. The parameters of interest are grain size, type of reaction and defects like anti site defects and grain or sub lattice boundaries. Simultaneously ex situ measurements on pure LiFePO4 are planned to use them as starting parameters for the more complex cathode system consisting of LiFePO4, Carbon Black and Binder. The PAS results will give new insight into the phase reactions of LiFePO4 during cycling. This unique in situ measurement method will allow a correlation between the development of defects and efficiency decay of cycled LIBs.Successful completion of the applied project in the above mentioned aspects will immensely improve the comprehension of the processes in LiFePO4.

目前，锂离子电池（LIB）是最有前途的储能候选者之一。该项目的目的是进一步了解阴极在循环过程中缺陷的产生及其性质。正电子湮没谱（PAS）被用来建立技术作为分析工具，原位缺陷表征的LIB。本研究的重点是LiFePO4作为正极材料。基于广泛使用的世伟洛克型电池系统，旨在设计一种既能满足PAS方法要求又能满足电池技术要求的原位电池。目的是观察循环过程中原子尺度上的阴极过程。重点是缺陷的行为，如晶格空位或由于相变的边界。我们的目标是了解和优化阴极材料中正在进行的工艺。具有先前未实现的时间分辨率的动态帕尔斯测量由提议者（Banhart，2011）开发，并将在本文中使用。关于PAS信号的材料参数的研究对于在LIB技术领域中使用PAS技术是重要的。感兴趣的参数是晶粒尺寸，反应类型和缺陷，如反位缺陷和晶粒或亚晶格边界。计划同时对纯LiFePO4进行非原位测量，以将其用作由LiFePO4、炭黑和粘合剂组成的更复杂阴极系统的起始参数。PAS结果将为LiFePO4在循环过程中的相反应提供新的见解。这种独特的原位测量方法将使缺陷的发展和循环LIB的效率衰减之间的相关性。成功完成上述方面的应用项目将极大地提高对LiFePO4过程的理解。