扣式锂离子电池原位XRD充放电测试分析

In-situ XRD Charging and Discharging Test of Button Lithium-ion Batteries

本文分别采用三元(NCM)、磷酸铁锂(LiFePO 4)材料制成的正极,金属锂片为负极,组装制备两种锂离子原位电池,并进行原位XRD测试及分析,发现两种材料呈现较大差别:(1)三元材料在充放电过程中某些特征衍射峰不仅强度出现较大变化,而且峰的位置也呈现规律性的变化。(2)磷酸铁锂材料在充放电过程中可以通过特征峰准确观测到LiFePO_(4)和FePO_(4)的相变,对应衍射峰的强度呈周期性变化但峰的位置基本不变。在充放电循环过程中,锂离子在电极材料间嵌入、脱出,会引起材料的结晶类型、晶格参数等发生变化,这些参数变化对研究反应过程机理和进一步提升电池性能有重要的意义。

Two kinds of lithium ion in-situ batteries were assembled by using ternary materials(NCM)and lithium iron phosphate materials(LiFePO 4)as cathode,and the lithium metal was used as the anode.The in-situ XRD test and analysis showed that the two materials showed great differences:(1)In the process of charge and discharge of ternary materials,the intensity of some characteristic diffraction peaks not only changes greatly,but also the position of the peaks changes regularly.(2)The phase transition of LiFePO_(4)and FePO_(4)can be accurately observed through characteristic peaks in the charge and discharge process of lithium iron phosphate materials,and the intensity of corresponding diffraction peaks changes periodically but the position of peaks is basically unchanged.In the process of charge and discharge cycle,lithium ions are embedded and removed between electrode materials,which causes changes in the crystal type and lattice parameters of the materials,and these parameter changes are of great significance for studying the reaction mechanism and further improving the performance of the battery.