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Three‐stage kinetics of laser‐induced LiFePO <sub/>4</sub> decomposition
摘要： This paper reports about new insight into a problem of a laser–matter interaction during Raman probing of lithium iron phosphate (LiFePO4), discusses phase transformation kinetics in powder samples, and provides methodological recommendations. LiFePO4 is the second most popular positive electrode material in the global lithium battery industry, but the use of Raman spectroscopy for its structural characterization is hampered by the laser‐induced degradation. The statistical/big‐data approach to Raman spectra measurements is utilized to revise the problem and suggest a simple model of laser‐induced phase transformations in powder LiFePO4. The results are proposed to be used for better understanding of the physics and chemistry of other processes taking place in electrochemical cells, namely, lithiation/delithiation and thermal stability/safety studies. Simple recommendations for nondestructive LiFePO4 characterization by Raman spectroscopy are formulated.
关键词： lithium iron phosphate,nondamaging characterization,statistical Raman spectroscopy,lithium batteries,statistical Raman microscopy
更新于2025-09-12 10:27:22
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Electrochromic effect of indium tin oxide in lithium iron phosphate battery cathodes for state of charge determination
摘要： In this paper, we discuss the origin of an optical effect in lithium iron phosphate (LFP) battery cathodes, which depends on the electrical charge transferred into the battery. Utilizing indium tin oxide (ITO) as an electrode additive, we were able to observe a change in reflectivity of the cathode during charging and discharging with lithiation and delithiation being clearly visible in the form of lithiation fronts. Further investigations using in situ video microscopy and in situ Raman spectroscopy on test cells with an optical window indicates that ITO additionally acts as an electrochromic marker within the LFP cathode. This enhances the optical effect due to local potentials around the lithiation fronts, which enables the voltage-dependent reflectivity of the ITO to be visible in the LFP cathode. Structural analysis with scanning electron microscopy (SEM) and X-ray crystallography (XRD) are presented as well. The observed effect allows for novel battery research methods and for a possible commercial application as a sensor for state of charge (SOC) estimation similar to the optical fiber approach reported by Ghannoum et al. for a graphite anode.
关键词： lithium ion batteries,battery state determination,lithium iron phosphate,raman spectroscopy,indium tin oxide,electrochromic marker,video microscopy,state of charge
更新于2025-09-04 15:30:14