Purely-natural stem based self-standing carbon current collector: Guiding internal preferred Li deposition via gradient conductivity

Lithium dendrite growth and unstable solid electrolyte interphase remain critical challenges for practical lithium metal anodes (LMA). Directly converted from plant stems, the monolithic and self-standing carbon current collector (ADC) inherits vertically aligned channels and abundant carbon defects from its natural precursor. By engineering a longitudinal electrical conductivity gradient, we construct an electrode denoted P-ADC-G (indicating the polymer coated and gradient-conductive anode) that enables co-regulate ion and electron fluxes, guiding sustained internal-preferred lithium deposition. Remarkably, this optimized kinetics unlocks high-rate electrodeposition, enabling rapid anode fabrication (10 mAh cm^-2 in just 2 h). The resulting Li@P-ADC-G composite anode exhibits exceptional stability, cycling over 2000 h at 4 mA cm^-2 with an average Coulombic efficiency of 97.56%, and enables LiFePO₄ full cells to retain above 70% capacity after 400 cycles at 1C. Moreover, the same ADC serves as an efficient metal-free cathode catalyst in Li–O₂ cells, achieving stable operation for over 800 h when paired with Li@P-ADC-G. This work demonstrates a scalable, bioinspired strategy for co-regulating ionic and electronic pathways to achieve highly reversible LMA across diverse battery chemistries.