A Sandwich CNTs-Si-CNTs Current Collector Enabling Uniform Lithium Plating for Anode-Free Lithium Metal Batteries

Anode-free lithium metal batteries (AFLBs) offer high energy density by plating Li directly on a current collector, but practical use is limited by dendrite growth and unstable SEI, which cause low Coulombic efficiency and rapid failure. Existing 3D hosts can still suffer top-surface-dominated deposition and poor pore utilization under polarization. Here, a sandwich CNT-Si-CNT current collector was prepared by gradient vacuum filtration. The embedded Si as lithiophilic sites could promote the internal deposition of Li in the carbon nanotubes (CNTs) network, while the 3D interconnected structure facilitates efficient electron transfer and ion diffusion. The Li plating/stripping behavior on CNT-Si-CNT was evaluated using a Li half-cell, symmetric-cell, and LFP full-cell test. The optimized 5Si-CNTs reduced Li nucleation overpotential to 21.3 mV and achieved an average CE of 90.53% over 100 cycles at 1 mA cm^-2 (2 mAh cm^-2). It also delivered stable symmetric-cell cycling (210 h at 0.25 mA cm^-2) with low polarization and improved LFP full-cell discharge capacity retention. Overall, embedding lithiophilic sites within a lightweight carbon nanotube (CNT) scaffold provides a practical route to more uniform Li plating and enhanced reversibility for AFLBs.