Engineering topics
Nguyen, Cao Cuong
Publications and source records attributed to Nguyen, Cao Cuong.
Citric Acid Based Pre-SEI for Improvement of Silicon Electrodes in Lithium Ion Batteries
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Systematic Investigation of Alkali Metal Ions as Additives for Graphite Anode in Propylene Carbonate Based Electrolytes
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Improved Cycling Performance of a Si Nanoparticle Anode Utilizing Citric Acid as a Surface-Modifying Agent
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Electrochemical reactivity of polyimide and feasibility as a conductive binder for silicon negative electrodes
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Improved cycling performance of Si nanoparticle anodes via incorporation of methylene ethylene carbonate
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In Situ Stress Evolution in Li 1+x Mn 2 O 4 Thin Films during Electrochemical Cycling in Li-Ion Cells
Real time monitoring of stress evolution in electrodes during electrochemical cycling can help quantify the driving forces that dictate their mechanical degradation. In the present work, in-situ stress evolution in thin films of spinel Li 1+x Mn 2 O 4 (LMO) was measured by monitoring the change in the elastic substrate curvature during electrochemical cycling in a specially designed beaker cell in the 3.5–4.3 V (vs. Li/Li+) voltage range. The LMO thin films were prepared using a solution deposition technique and their structures and morphologies were characterized by X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM). The stress evolution in the early part of the first delithiation cycle (<4.05 V) was consistent with the XRD data. However, stress evolution during later stages of the first delithiation cycle (>4.05 V) was not consistent with the XRD results, and showed irreversible behavior, suggesting irreversible changes in the electrode. Beyond the first delithiation cycle, the stress evolution was reversible, with a steady buildup of compressive and tensile stress during lithium insertion and extraction, respectively. Measurements on LMO films of varying thicknesses suggest that the first cycle irreversibility in stress response arises primarily from the electrode bulk.
Capacity Fading Mechanisms of Silicon Nanoparticle Negative Electrodes for Lithium Ion Batteries
A thorough analysis of the evolution of the voltage profiles of silicon nanoparticle electrodes upon cycling has been conducted. The largest changes to the voltage profiles occur at the earlier stages (> 0.16 V vs Li/Li + ) of lithiation of the silicon nanoparticles. The changes in the voltage profiles suggest that the predominant failure mechanism of the silicon electrode is related to incomplete delithiation of the silicon electrode during cycling. The incomplete delithiation is attributed to resistance increases during delithiation, which are predominantly contact and solid electrolyte interface (SEI) resistance. The capacity retention can be significantly improved by lowering delithiation cutoff voltage or by introducing electrolyte additives, which generate a superior SEI. The improved capacity retention is attributed to the reduction of the contact and SEI resistance.
Characterizing Solid Electrolyte Interphase on Sn Anode in Lithium Ion Battery
Tin (Sn) nanoparticle electrodes have been prepared and battery cycling performance has been investigated with 1.2 M LiPF6 in ethylene carbonate (EC) / diethyl carbonate (DEC) electrolyte (1:1, w/w) with and without added vinylene carbonate (VC) or fluoroethylene carbonate (FEC). Incorporation of either VC or FEC improves the capacity retention of Sn nanoparticle electrodes although incorporation of VC also results in a significant increase in cell impedance. The best electrochemical performance was observed with electrolyte containing 10% of added FEC. In order to develop a better understanding of the role of the electrolyte in capacity retention and solid electrolyte interface (SEI) structure, ex-situ surface analysis has been performed on cycled electrodes with infrared (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and Hard XPS (HAXPES). The ex-situ analysis reveals a correlation between electrochemical performance, electrolyte composition, and SEI structure.