Regulating lithium metal interface using seed-coating layer for high-power batteries

Abstract

• Li metal interface is engineered using seed-coating of N-rich graphene quantum dots. • A regulated SEI on Li metal assures ultra-stable cyclability even at 30 mA cm −2 . • Li is uniformly guided beneath seed-coating layer with dendrite-free plating. • Robust and stable composite SEI mitigates continuous consumption of electrolyte. Li metal has received heightened attention as an anode material for next-generation batteries due to its extremely large theoretical specific capacity. Employing Li metal anodes, however, involves considerable challenges, such as the formation of Li dendrites, depletion of electrolyte, and breakage of the solid electrolyte interphase layer. These issues potentially limit cell cycle life and pose safety risks. While recent studies demonstrated promising results, facile and scalable methods for achieving high power Li metal batteries are still elusive. Herein, the interface of lithium metal is regulated by seed-coating of nitrogen-rich graphene quantum dots (N-GQDs), which facilitates the formation of a robust and stable solid electrolyte interface layer. The highly lithiophilic nature of N-GQDs enables uniform lithium ionic flux even at high current densities and promotes dendrite-free lithium plating morphology with a low nucleation overpotential of 3 mV (45 mV for bare copper). Such a robust layer enables highly reversible Li plating/stripping in symmetric cell configuration for over 8,000 h at a current density of 30 mA cm −2 . Furthermore, the lithium iron phosphate-coupled full cell performs stable cycling for over 500 cycles. The introduction of seed layers represents a viable strategy for achieving high-power Li metal batteries by regulating the highly reactive lithium metal surface.