張家欽

Abstract:

In this study, we investigated the effects of electrolyte additives as LiPO₂F₂ on the SEI film and battery performance using two types of graphite. Comprehensive results obtained through cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and small-angle neutron scattering analysis (SANS). Analysis from SANS and EIS showed a positive correlation between SEI thickness variation and impedance change, which in turn affects the rate of lithium ion diffusion. Observations from electrical performance testing indicated that the impact of SEI thickness on cycle life is not absolute. This is because the choice of additives affects the molecular structure characteristics of the SEI composition, thereby influencing mechanical strength and forming a more stable state.

Except that there are complex materials in the 18650 full battery assembly which makes the target peaks difficult to be distinguished. Thus, we propose to use a cold triple-axis spectrometer which provides, high-resolution and clean background neutron scattering pattern via using its analyzer to yield a more detailed picture of evolution. The study on the lithium diffusion mechanism of Li⁺ diffusion in LiC₆ , LiC₁₂ of the graphite and the electrolyte additives (as LiPO₂F₂) at low temperature (253 K or 268 K) were very importance for the lithium plating and long cycle. Therefore, SIKA is the instrument good for experimenting with low temperatures to understand the Li+ diffusion effect in the cell of NMC/graphite LIB to understand the state-of-health (fatigue) in different temperatures to give an ideal to improve the battery design and to resolve the lithium plating issue in the low temperature which regarding to the safety. We will also pay attention to the formation of lithium plating which is highly related to battery safety.

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