Dense nano-tips homogenize lithium deposition

Lithium metal batteries (LMBs) offer high energy density but suffer from dendrite growth and interfacial instability, hindering practical application. We present a novel strategy that repurposes the “tip effect” to achieve uniform lithium deposition and suppress dendrite formation. By designing a three-dimensional Cu/Fe₃O₄ Mott-Schottky heterojunction array with a high-density nano-tip structure, we homogenize the surface charge distribution, preventing current hotspots that induce dendrite growth. The Mott-Schottky heterojunction generates a robust built-in electric field that enriches Li⁺ concentration at the electrode surface, mitigates Li⁺ depletion, and homogenizes the electric field distribution. Simultaneously, the ferromagnetic Fe₃O₄ induces an internal magnetic fields, utilizing the magnetohydrodynamic effect, redirects Li⁺ trajectories away from surface protrusions, thereby suppressing dendritic nucleation. Experimental and computational analysis confirm that this beneficial tip effect and coupled dual-field mechanism can effectively promote uniform lithium deposition, achieving a plating and stripping Coulombic efficiency of 99.2%. Consequently, the symmetric cell achieves an ultralong cycle life of over 3000 h at 1 mA cm⁻² with an ultralow overpotential of 12 mV. When paired with a high-loading LiFePO₄ cathode (11.25 mg cm⁻²), the full cell maintains 95% of its initial capacity after 200 cycles, demonstrating exceptional rate capability and interfacial stability. For high-voltage cathode LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811), Li-Cu/Fe₃O₄||NCM811 cell achieves a capacity retention rate of 94.8% after 150 cycles at 2 C. This work provides an innovative solution for controlling lithium deposition, offering a promising strategy for high-performance LMBs.