Xianhang Lu, Ming Hao, Yunhe Fu, Kaiyuan Ji, Weiran Fu, Shuowen Meng, Yuanhua Xie, Yaoshuai Ba, Dechun Ba, Kun Liu, Northeastern University, Shenyang, China
The rapid advancement of electric vehicles, drones, robotics, and other emerging applications has imposed higher demands on the energy density of energy storage batteries. Lithium metal is hailed as the ""Holy Grail"" anode material for next-generation high-energy-density storage devices, owing to its ultra-high theoretical specific capacity (3860 mAh g^-1) and the lowest electrochemical potential (-3.04 V vs. SHE). However, its practical application is hampered by poor capacity retention during cycling. In this work, we address this challenge by introducing a lightweight polymer-based composite current collector fabricated via a hybrid vacuum evaporation deposition and electroplating process, and evaluate its efficacy in stabilizing lithium metal anodes. The as-prepared polyethylene terephthalate-copper (PET-Cu) composite foil features a highly crystalline copper coating, and a dense, pinhole-free surface morphology. When employed as the substrate for Li deposition in asymmetric cells (vs. Li metal), the PET-Cu demonstrates superior lithiophilicity compared to traditional bare Cu foil. The nucleation overpotential is significantly lower for PET-Cu (23 mV) than for conventional Cu (28 mV) at 1 mA cm^-2 for 1 mAh cm^-2. This reduced overpotential facilitates more uniform deposition. Consequently, the PET-Cu electrode exhibits markedly enhanced cycling stability. While both electrodes show similar initial coulombic efficiencies (97.68% for PET-Cu vs. 96.97% for bare Cu over the first 10 cycles), the bare Cu electrode suffers a catastrophic drop to 6.72% by the 20th cycle. In contrast, the PET-Cu electrode maintains a high CE of 98.1% after 50 cycles. Linear sweep voltammetry test results further elucidate the origin of the initial efficiency loss. These results demonstrate that the PET-Cu is a highly promising lightweight current collector for enabling long-lived and high-energy lithium metal batteries.

References:
1. X. H. Lu, M. Hao, K. Liu*. et al. Metalized plastic current collectors: Bridge to high energy density reconciling high safety for lithium-ion batteries. Journal of Energy Storage, 2025, 125, 116813.
2. X. Wang, W. Zeng, L. Hong. et al. Stress-driven lithium dendrite growth mechanism and dendrite mitigation by electroplating on soft substrates. Nature Energy, 2018, 3(3), 227.
Funding: The LiaoNing Transplant with Soil Program of Revitalization Talents Plan (XLYC2204011).