Carrier Depletion-Induced Suppression of Solid Electrolyte Interphase and Conversion Reaction in Zn_1-x Mg _x O Nanocrystal Solid Solution Li-Ion Batteries

초록

In this study, we investigated the effects of charge carrier depletion on the formation of the solid-electrolyte interphase (SEI) followed by conversion reaction involving alloying/dealloying reactions during the cycling of Li-ion batteries. In our investigation, Zn1-x Mg- x O nanocrystal solid solutions were used as the anode, focusing on a range where x varied between 0.05 and 0.15. We observed that a significant decrease in electrical conductivity occurred at x = 0.15, accompanied by a marked decrease in field-effect transistor (FET) mobility and carrier concentration. Consequently, both SEI formation and the conversion reaction were suppressed in the initial discharge process, resulting in a specific capacity significantly lower than that of ZnO (x = 0). Our findings revealed that the Zn0.85Mg0.15O sample exhibits a strong depletion of surface charge carriers by trapping compared to ZnO and Zn0.95Mg0.05O. This was demonstrated by ultraviolet (UV)-induced (FET) and photoluminescence (PL) measurements. Since the processes of Li-ion alloying, ZnO reduction, and SEI formation are influenced by trap-induced surface carrier depletion, controlling these traps could enhance the energy density of Li-ion batteries. This advancement holds particular significance for high-demand applications, such as electric vehicles and grid storage systems.

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