2D PdTe₂ Thin-Film-Coated Current Collectors for Long-Cycling Anode-Free Rechargeable Batteries

The practical implementation of anode-free batteries is limited by factors such as lithium dendrite growth and low cycling Coulombic efficiency (CE). In this study, the improvement in the electrochemical performance of anode-free rechargeable lithium batteries bearing a Cu current collector (CC) coated with PdTe₂ thin films is reported. The optimized thickness and sputtering heating conditions of the PdTe₂ layer are 15 nm and 473.15 K, respectively. Upon deposition on a CC, PdTe₂ works as a seed layer that considerably improves the CE in half-cells, owing to its unique 2D structure that reduces the nucleation overpotential. A further contribution to the high performance is brought about by a CuTe interphase between the coating layer and Cu CC formed during heating. Such an interphase contributes to the high CE by improving the uniformity of the current density distribution on the CC that suppresses lithium dendrite growth. A low nucleation overpotential and uniform current density distribution, in turn, result in a smooth morphology of the plated Li. The full cell obtained with the PdTe₂-coated CC exhibits a capacity retention of 70.7% after the 100th cycle, with an average CE of 99.65% at a 0.2C rate─an outstanding result in view of the rapid development of lithium-ion batteries.