Preparation of Ultra‐Thin Copper Foil for Enhancing the Lithium Metal Batteries Properties by Recycling Waste Printed Circuit Boards

Among all metals in waste printed circuit boards (WPCBs), copper has the highest content and therefore carries significant recycling value. Meanwhile, as the anode current collector, ultra-thin copper foil has great potential to enhance the performance of anode-free lithium metal batteries (AFLMBs). However, the control of its complete stripping and mechanical properties still hinders this process. Herein, by utilizing a molybdenum substrate for the first time with a benzotriazole (BTA) stripping layer, the 3.5 µm ultra-thin electrolytic copper foil (Ut-Cu) with a tensile strength of 428 MPa is prepared and easily stripped through recycling WPCBs, presenting a highly preferred (111) orientation and nanotwin microstructure. When used as the anode current collector in LMBs, the Li||Cu half-cells show more uniform lithium deposition and exhibit an average Coulombic efficiency (CE) of 97.7% over 300 cycles at 0.5 mA cm^-2. Furthermore, the Li@Cu||LFP cells retain 89.7% capacity after 200 cycles at room temperature, and the Cu||LFP (anode-free) cells with Ut-Cu show 68.8% capacity retention after 100 cycles, with the mass energy density increasing 39.4% compared with the commercial electrolytic copper foil (Com-Cu). Moreover, the average copper recovery rate of WPCBs can reach as high as 67.7%, conducive to environmental protection and turning waste into treasure.