Achieving Dendrite-Free Lithium Metal Batteries by Constructing a Dense Lithiophilic Cu_1.8Se/CuO Heterojunction Tip

Lithium (Li) metal batteries (LMBs) have garnered widespread attention due to their high specific capacity. However, the growth of lithium dendrite severely limits their practical applications. Herein, a novel strategy is proposed to regulate the overall potential strength and lithium ions (Li⁺) concentration on the surface of the current collector by utilizing densely distributed tip effects. This concept is exemplified through the construction of lithiophilic Cu_1.8Se/CuO heterojunction needle array on the Cu foil, ultimately achieving dendrite-free lithium deposition. Based on the simulation in COMSOL multiphysics and experimental research, this design is demonstrated to enrich Li⁺ on the current collector surface, delay the formation of space charge regions, and mitigate the growth of lithium dendrites. Additionally, a built-in electric field (BIEF) triggered by the heterointerface between Cu_1.8Se and CuO further alleviates the Li⁺ concentration gradient on the electrode surface, achieving uniform bottom-up deposition of Li within the array structure. Consequently, the symmetrical cell exhibits an ultra-long cycle life of 2400 h (1 mA cm^-2, 1 mAh cm^-2) with an extremely low overpotential of 13 mV. Furthermore, full batteries using LiFePO₄ as the cathode exhibit superior cycle stability and rate performance. This study presents a promising approach for designing dendrite-free current collectors in LMBs.