Lithium is believed to be an ultimate anode solution for new-generation rechargeable batteries. Yet, its stable cycling remains a challenge, specifically at an acceptable and even high areal loading that dominates the performance at the cell level. 

Recently, a research group led by Prof. LI Xianglong from National Center for Nanoscience and Technology of the Chinese Academy of Sciences has demonstrated a leaf vein-inspired spatially modulated hosting strategy, enabling stable and dendrite-free lithium deposition markedly in a loading scalable manner. This study was published in Matter. 

Inspired by leaf veins, the researchers first constructed a self-supporting wood-derived carbon membrane with vertically aligned micro-channels covered by randomly-networked carbon nanofiber mats, namely, capillarity-involved low-tortuosity carbon membrane (CTC). 

The electrolyte wetting experiments further corroborates superb capillarity and electrolyte wetting character of such a membrane, attributable to blanketing of carbon nanofiber mats. 

When the as-fabricated membrane was used as the lithium host, extraordinary cyclic stability was observed under various loadings and current densities (up to 40 mAh cm^-2 and 40 mA cm^-2, respectively). Noticeably, stable dendrite-free cycling up to 1080 cycles was realized with overpotential of only 30 mV at 30 mAh cm^-2 and 10 mA cm^-2. 

Besides, the researchers demonstrated the viability of this membrane, as reflected by a prototype full cell showing stable cycling and enhanced rate capability (86 and 81% capacity retention is achieved after 200 and 350 cycles at a practical loading level of 3.4 mAh cm^-2, respectively). 

It was emphasized that the performance achieved is ascribed to the spatial hierarchy of this membrane that mimics ‘division of labor’ in a leaf venation. Specifically, the vertical channels enable low tortuosity to allow creating fast ion transport highways in the long range while accommodating the volume change. More impressively, the verified strong capillarity facilitates establishment of homogeneously-spread but localized three-dimensional micro-reservoirs, which, in the short range, homogenizes lithium ion distribution and scalable lithium deposition. 

The study offers a conceptually distinct and promising option for high-performance lithium metal anodes, and may provide a spatially hierarchical paradigm for both the rational design and construction of other applicable metal battery anodes toward practical use.