Highly Stable and Multifunctional ZnNi Alloy Nanoarrays for Long-Life Anode-free Lithium Metal Batteries.

Abstract

Nickel (Ni) foil current collectors exhibit high stability, making them promising candidate materials for next-generation high-performance anode-free lithium metal batteries (AFLMBs). However, the inherent lithiophobicity of Ni foil results in compromised reversibility of lithium deposition and stripping on its surface, significantly limiting its practical application. Herein, a ZnNi alloy layer (ZnNi@Ni) is fabricated on Ni foil via thermal evaporation and an <i>in situ</i> alloying method. Uniform ZnNi nanoarrays with strong adhesion to the substrate are constructed, providing abundant lithiophilic nucleation sites while maintaining electrochemical inertness toward metallic Li. In contrast, the lithiophilic Zn coating used as a control sample suffers mechanical failure due to alloying-induced volume expansion during lithium deposition, ultimately compromising its lithiophilicity. Density functional theory (DFT) calculations confirm ZnNi's enhanced lithiophilicity and strong adsorption of TFSI^- anions, which synergistically reduce Li nucleation barriers, guide uniform Li deposition, and promote LiF-rich SEI formation. Consequently, Li deposition with a high areal capacity (10 mAh cm^-2) and low volume expansion is achieved on ZnNi@Ni. In ZnNi@Ni||Li half-cells, and significant reversibility is demonstrated, sustaining 800 cycles at 1 mA cm^-2, 1 mAh cm^-2 with 99.21% average Coulombic efficiency (CE), and 250 cycles under more rigorous conditions (3 mA cm^-2, 6 mAh cm^-2) with 99.40% CE. When assembled into AFLMB with a Ni-rich ternary cathode (LiNi_0.94Co_0.03Mn_0.03O₂, NCM-Ni94) and Li₃N prelithiation, the battery retains 89.6% capacity after 100 cycles and delivers an energy density exceeding 400 Wh kg^-1. This work demonstrates a high-performance lithiophilic material design strategy, offering a promising route toward practical high-energy-density AFLMBs.