Achieving a Superior Lithium Metal Anode by a Hollow Nanocubic Carbon with an Inside-Out Lithiophilic Gradient

The lithium metal anode (LMA) offers high theoretical capacity and low electrochemical potential but faces challenges including uncontrolled dendrite growth, unstable solid electrolyte interphase (SEI), and infinite volume expansion. This study designs and constructs a nitrogen-doped hollow nanocubic carbon with an inside-out lithiophilic gradient (Co/ZnO-HNC) as the LMA host. On one hand, the inside-out gradient-lithiophilic ZnO and Co sites enable lithium nucleation and growth from the interior to exterior of the hollow carbon nanocube, inducing the dendrite-free Li plating/stripping. On the other hand, the hollow nanocubic structure provides confined space for Li storage and buffers the volume change of Li during cycling. Consequently, the Co/ZnO-HNC electrode exhibits an ultralow nucleation overpotential (3.7 mV) at 1 mA cm^-2 and cycles stably for 300 times with an average Coulombic efficiency of 98.8% in half-cells. When matched with a commercial LiFePO₄ cathode (20 mg cm^-2), the full cell retains a 91.9% capacity retention over 200 cycles at 1 C with a high reversible capacity of 133.8 mAh g^-1. Therefore, this work provides a scalable and effective strategy for designing gradient-lithiophilic frameworks to achieve high-performance lithium metal batteries.