Natural forest-inspired Ag lithiophilic porous arrays grown in Cu foam hosts with bi-continuous electronic/ionic pathways for highly stable Li metal anodes

Abstract

A pine forest-inspired superior Li host with high lithiophilicity and bi-continuous electronic/ionic pathways was successfully fabricated by in situ growth of needle-branch-like Ag hierarchical porous arrays on the skeleton surface of commercial Cu foam via a simple displacement reaction of pure Cu in an AgNO₃ aqueous solution. It is demonstrated that the super-lithiophilic properties of the Ag array coating and the capillary effect of its hierarchical porous structures synergistically contribute to the excellent Li-wettability of the Ag@Cu foam hosts for the fast impregnation and uniform deposition of molten Li. Moreover, the pine needle-branch-like Ag hierarchical porous array structures of the coating layers on the Cu skeleton surfaces could provide large surface areas and bi-continuous electronic/ionic pathways for uniform Li plating and stripping with fast electrochemical reaction kinetics. Consequently, the obtained Li/Ag@Cu composite anodes could effectively buffer the volume fluctuation and prohibit the Li dendrite growth, demonstrating an ultra-long-term lifetime of Li plating/stripping over 500 cycles with a low overpotential of 3 mV at 1 mA cm⁻², and over 1500 cycles with an overpotential of 6 mV even at a high rate of 5 mA cm⁻² in symmetric cells. Furthermore, full cell configurations with the Li/Ag@Cu composite anodes and LiFePO₄, LiNi_0.8Co_0.1Mn_0.1O₂ or S cathodes also exhibit significantly enhanced cycling capacity and rate performance. These encouraging results indicate that the natural forest-inspired, pine needle-branch-like Ag hierarchical porous array coated Cu foam should be an attractive Li host for fabricating dendrite-free lithium metal anodes for advanced high-energy-density lithium metal batteries.