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In this work, ethyl 5-amino-4-cyano-3-(2-ethoxycarbonylmethyl) thiophene- 2-carboxylate (TAEC) is proposed as a functional electrolyte additive for lithium metal batteries using high-voltage LiCoO2 cathode. The TAEC molecular contains the -CN, -NH2 and ester groups on the thiophene core, so that it cannot only improve the cathode electrolyte interface (CEI) on the 4.5 V LiCoO2 surface, but also stabilize the solid electrolyte interface on the lithium metal for lithium dendrite suppression. The TAEC-containing electrolyte exhibits the enhanced cycling stability in Li||LiCoO2 batteries in the range of 3.0~4.5 V, compared to the conventional electrolyte. Especially, the Li||LiCoO2 cell with the 0.3 wt% TAEC-containing electrolyte delivers a high capacity of 162.7 mAh g-1 after 100 cycles with the capacity retention of 85.1%, far superior to that using the conventional electrolyte (51.2 mAh g-1, 27.5%). Interfacial characterizations prove that TAEC can help to form a thin CEI film with reduced interface impedance and suppress the lithium dendrite growth in lithium metal batteries. [ABSTRACT FROM AUTHOR]