Molecular engineering of two-dimensional polyamide interphase layers for anode-free lithium metal batteries.

Anode-free lithium (Li) metal batteries are promising candidates for high-performance energy storage applications. Nonetheless, their translation into practical applications has been hindered by the slow kinetics and reversibility of Li plating and stripping on copper foils. Here we report a two-dimensional polyamide (2DPA)/lithiated Nafion (LN) interphase layer for anode-free Li metal batteries. Through molecular engineering, we construct a 2DPA layer with a large conjugated structure and Li-ion adsorption groups that show efficient adsorption, distribution and nucleation of Li ions. 2DPA molecules assembled into two-dimensional sheets are further incorporated with LN to create an ultrathin interphase layer with high-rate, high-capacity Li plating/stripping. These 2DPA/LN layers have higher rate capabilities and maximal energy and power densities compared with alternative polymer interphase layers, enabling the fabrication of an anode-free pouch cell with high performance. Overall, our interphase engineering approach is a promising tool to push the translation of anode-free Li metal batteries based on two-dimensional polymer interphase layers into practical devices, and enable the fabrication of energy storage technologies with high energy and power densities.