Functional organic 7,7,8,8-tetracyanoquinodimethane artificial layers for the dendrite suppressed lithium metal anodes

Abstract

The large-scale industrialization of lithium metal (Li), as a potential anode for a high energy density energy storage system, has been hindered by dendrite growth. The construction of an artificial solid electrolyte interphase layer featuring high ionic and low electronic conductivity has been verified to be a high-performance strategy to confine the dendrite growth and promote the Li anode stability. Therefore, a functional organic protective layer is homogeneously deposited on the Li anode surface via an in situ chemical reaction between tetracyanoquinodimethane (TCNQ) and Li. The as-synthesized Li_n-TCNQ organic film could efficiently trap non-uniform Li deposition and restrain dendrite propagation. Particularly, an asymmetric M-TCNQ-Li|Cu cell with the Li_n-TCNQ layer breezed through a high Coulombic efficiency of 91.15% after 100 cycles at 1.0 mA cm⁻². The M-TCNQ-Li|NCM622 cell delivered a high capacity of 143.40 mAh g⁻¹ at 0.2 C and maintained a good cyclic stability of 110.44 mAh g⁻¹ after 160 cycles. The analysis results of spectroscopic tests further demonstrate that the Li_n-TCNQ with the enhanced absorption energy is conducive to lithiophilicity and decreases the overpotential of Li deposition.