科研之友
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摘要
Graphite anodes experience co-intercalation of K+ ions and solvent in ether-based electrolytes, which enables ultrafast kinetics of potassium-ion storage. The potassium-ion storage mechanisms of amorphous soft carbon (SC) and hard carbon (HC) anodes in ether-based electrolytes are ambiguous. Herein, the co-intercalation mechanisms of SC and HC in ether-based electrolytes are elucidated. The solvated K+ intercalates with a solvation structure, which avoids the sluggish desolvation process. Thus, HC and SC anodes display excellent rate capabilities. Moreover, the SC anode forms ternary K-graphite intercalation compounds during the potassiation process. It is also demonstrated that solvated K+ is not only stored in the spacing between graphene nanodomains but can also be stored in the closed pores of HC, enabling higher capacities than pure K+ intercalation in ester-based electrolytes. Nevertheless, the co-intercalation causes the large volume expansion of SC and HC, giving rise to irreversible structural damage and capacity decay of SC and HC. The strong interaction between K+ ions and ether molecules is the main reason for the co-intercalation. A thick and organic-rich solid electrolyte interphase film formed in ester-based electrolytes can hinder the co-intercalation in ether-based electrolytes. @@@ The solvated K+ is not only stored in the graphene nanodomains but can also be stored in the closed pores of hard carbon (HC), enabling higher potassium-storage capacities than pure K+ intercalation in ester-based electrolytes. Nevertheless, the co-intercalation causes the large volume expansion of HC, giving rise to irreversible structural damage and capacity decay of HC.image
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单位广东工业大学
