Redistributing zinc-ion flux by work function chemistry toward stabilized and durable Zn metal batteries

Abstract

Zn metal-based batteries (ZMBs) are widely considered to be promising energy storage devices due to their cost-effective and safety features, but uneven Zn²⁺ deposition facilitates rapid dendrite growth. Here, we introduce a novel work function chemistry strategy to improve the Zn²⁺ flux and transport kinetics via wrapping a series of nitrides (WN_0.67, VN, Mo₂N, and NbN) on a commercial glass fiber (GF) separator. Density functional theory and experimental evaluation reveal that nitrides with a lower work function exhibit enhanced capability in reconstructing the Zn²⁺ flux and spontaneously repelling detrimental SO₄²⁻. Additionally, the NbN@GF separator can suppress the side reactions and promote a preferred orientation of the (002) crystal plane, thus achieving dendrite-free growth of Zn metal in the horizontal direction and enabling reversible Zn cycling of ∼3000 h. As a proof of concept, the Zn full cells, coupled with Mn-MIL-100-derived Mn₃O₄@C polyhedra and the NbN@GF separator, achieve an exceptional capacity retention of 85.3% after 4000 cycles. The design of a multifunctional NbN-modified separator and the proposed strategy of work function chemistry provide practical universality for studying battery separators.