N-Rich Bilayer Solid Electrolyte Interphase toward Highly Reversible Lithium Metal Batteries

Continuous lithium (Li)/electrolyte interfacial reactions and uncontrollable Li dendrites severely hamper the application of paradigmatic Li metal batteries (LMBs). Aiming to address the above-mentioned crucial issues, N-rich polymer-inorganic bilayers at the Li/electrolyte interface are designed via nitrate-rich electrolytes, achieving high-energy-density and long-lifespan LMBs. The inner layer of Li₃N favors rapid and uniform Li⁺ deposition, while the outer layer of N-containing flexible polymers facilitates uniform Li⁺ distribution at the interlayer and accommodates volume changes during cycling. The synergistic effect of N-rich polymer-inorganic bilayers promotes the formation of dense uniform spherical nuclei morphology instead of dendrites, thus significantly improving the plating-stripping reversibility of LMBs. Attributed to the unique interphase, the Li|Li cell can stably run for over 1000 h at 1.0 mA cm^-2 with an even deposition morphology, which is monitored and proven by in situ optical microscopy. Moreover, the assembled Li|S cell displays a high capacity of 697.6 mA h g^-1 for over 150 cycles and a 99% Coulombic efficiency. This work paves the way for designing high-energy and long-lifespan LMBs.