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/Fe 3 O 4 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 Fe 3 O 4 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 hours at 1 mA cm −2 with an ultralow overpotential of 12 mV. When paired with a high-loading LiFePO 4 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 0.8 Co 0.1 Mn 0.1 O 2 (NCM811), Li-Cu/Fe 3 O 4 ||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. This study designs a 3D Cu/Fe 3 O 4 Mott-Schottky heterojunction with a high-density nano-tip structure, repurposing the “tip effect” to achieve uniform lithium deposition and suppress dendrites. The coupled dual-field mechanism (built-in electric field and internal magnetic field) effectively regulates Li + distribution. The strategy enables ultralong cycle life (over 3000 hours) and demonstrates excellent stability in high-loading LFP and NCM811 full cells. • A nano-tip array (Cu/Fe 3 O 4 heterojunction) repurposes the “tip effect” to achieve uniform, dendrite-free lithium deposition. • The synergistic electric-magnetic field couples to homogenize Li + flux and electric field distribution. • The symmetric cell achieves an ultralong cycle life of over 3000 hours with a low overpotential of 12 mV at 1 mA cm −2 . • Full cells paired with high-loading LFP and high-voltage NCM811 cathodes exhibit exceptional capacity retention.