Expandable Bidirectional-Gradient Current Collector for High-Performance Li Metal Battery

Abstract

3D porous current collectors (CCs) play a critical role in ensuring uniform lithium (Li) deposition and distributing current density evenly across electrode surfaces. These attributes are essential for improving the safety and stability of Li metal batteries. However, current 3D copper (Cu) -based CCs face notable drawbacks, such as rigid structures, insufficient pore volume, excessive mass, and weak intrinsic lithiophilicity for Li, which hinder their performance. To overcome these limitations, a novel self-assembly method is developed to construct a highly expandable bidirectional-gradient current collector (EBG CC). This advanced design integrates Cu-silver (Ag) -Cu nanowires and offers high porosity, which provides ample space for Li deposition. The unique gradients in lithiophilicity and conductivity within the EBG CC enable uniform Li nucleation, thereby ensuring stable and efficient cycling performance. Electrochemical testing in half-cell and symmetric cell configurations demonstrated the EBG CC's superior rate capabilities and long-term capacity retention. Additionally, a bidirectional pouch cell configured as Li/EBG CC | LiFePO₄ | Li/EBG CC delivered an impressive discharge capacity of 160.3 mAh g⁻¹ at 1C. These results underline the potential of lightweight, porous, and expandable current collectors in mitigating Li dendrite growth and significantly enhancing the performance of Li metal anodes.