Controlling Lithium Surface Diffusivity via 2D PtTe₂, PdTe₂, and NiTe₂ Coatings for Anode-Free and Lithium Metal...

Anode-free Li-ion batteries (AFLBs) and Li-metal batteries (LMBs) offer superior energy densities compared to conventional Li-ion batteries with graphite anodes. However, they degrade faster owing to their lower Coulombic efficiency, primarily caused by uneven Li deposition on the current collector (CC) in AFLBs or the Li-metal anode (LMA) in LMBs. Coating CCs and LMAs has emerged as a promising strategy to enhance the CE. Coating CCs and LMAs with PtTe₂, PdTe₂, and NiTe₂-metallic 2D transition metal dichalcogenides-reveals the critical factors for achieving uniform Li plating. The PtTe₂ coating facilitates rapid Li surface diffusivity, while the PdTe₂ and NiTe₂ coatings provide shorter diffusion paths for Li adatoms on the CCs and LMAs. In addition, Li₂Te, formed as a byproduct of the decomposition of PdTe₂ and NiTe₂ during Li plating, reduces the critical nucleus size by minimizing the interfacial energy between the electrolyte and the plated Li. PtTe₂ more effectively enhances the AFLB cycling performance, whereas PdTe₂ and NiTe₂ are more advantageous for LMBs. Notably, a 5-nm-thick PdTe₂ coating on the LMA achieves 80% capacity retention after 450 cycles using a LiFePO₄ cathode (3 mAh cm^-2) at a 0.5 C-rate.