Lithiophilic diffusion barrier layer on stainless steel mesh for dendrite suppression and stable lithium metal anode

Lithium metal battery has high theoretical specific capacity but suffers from dendrite growth that leads to low Columbic Efficiency (CE) and uncontrolled volume expansion during cycling. Here, we develop a method for fabrication of a nitrogen-doped carbon-coating as a lithophilic diffusion barrier layer, by carbonizing polydopamine (PDA) on three-dimensional (3D) porous stainless steel (called Nitrogen-doped carbon stainless steel, N-C-SS) mesh, and used it as the current collector for Li metal anode. With this layer, we observed significant suppression of Li dendrite formation during Li deposition. More specifically, the N-C-SS/Li anode in symmetric cells exhibit stable cycling for over 1800 h, 4 times longer than the bare Li electrode. Similarly, the fabricated half cells retain an average CE of 98.1% after cycling 400 times and show a low overpotential of 12 mV, while for fabricated full cells, they retain 98.6% of their initial capacity 140 mA h g−1 after 200 cycles at 3C. Density functional theory (DFT) calculation results show that N-C-SS surface enables higher diffusion barrier, with more negative Li adsorption energy than the untreated SS surface or Cu or Li substrate, which guides Li nucleation and suppresses dendrite growth on the barrier layer. An additional advantage of SS framework is that the 3D SS mesh skeleton distributes Li along with the mesh uniformly and provides ample voids to accommodate high Li loading (>10 mA h cm−2), while simultaneously minimizes local current density.