Application of Galvanostatic Intermittent Titration Technique to Investigate Phase Transformation of LiFePO4 Nanoparticles. (1st July 2017)

• Record Type: Journal Article
• Authors: Chen, Yuqing; Wang, Li; Anwar, Tauseef; Zhao, Yun; Piao, Nan; He, Xiangming; Zhu, Quanyao
• Is Part Of: Electrochimica acta. Volume 241(2017)
• Page Start: 132
• Page End: 140
• Publication Date: 2017-07-01
• Subjects: LiFePO4 nanoparticles -- phase transformation -- GITT measurement -- kinetics; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2017.04.137
• Languages: English
• ISSNs: 0013-4686

Abstract

Highlights: GITT was applied firstly to study phase transition to support in-situ experiments with kinetic calculation. Higher C-rates contribute to faster equilibrium of OCV due to the faster phase transformation. GITT measurement showed phase transition pathway between both ends and mid-stage is different and might be closely related with C-rates. Phase transformation study benefits for optimizing the design of LiFePO4 battery and improve electrochemical properties of battery electrodes. Abstract: The lithiation/delithiation of phosphate electrode materials in lithium ion batteries is often accompanied by an electrochemically driven phase transformation. The good understanding of phase transformation benefits for evaluation of SOC (state of charge) by OCV (open circuit voltage). A facile GITT (Galvanostatic Intermittent Titration Technique) is attempted to investigate the phase transformation kinetics of multi-particles LiFePO4 (LFP) nanoparticles in different depth of charge/discharge. The process of charge/discharge is divided by 20 sections, in which the cell is charged/discharged by the 5% capacity at different C-rates and then gets rest for 30 minutes. The polarization can include the kinetics of phase transformation and concentration diffusion. The detailed analysis of polarization data reflects the information of phase transformation, especially kinetics of phase transformation. Here, the result shows that the higher C-rates make quicker equilibrium of OCV in 30 minutes rest. This is consistent with the phase transformation theory as proven in this paper that the higher C-rates make the faster phase transformation. It is also displays that phase transformation is different between two ends and middle parts, and dependent on C-rates. The proposed approach paves a facile and effective way to investigate the phase transformation of phosphate electrode.