Pressure-tuned and surface-oxidized copper foams for dendrite-free Li metal anodes

The applications of Li metal anode in next-generation batteries, have been impeded by virtually infinite volume change and inevitable side reactions between Li metal and electrolytes. To address the issues, current collectors have to possess a porous structure and a lithiophilic surface. However, how to achieve a tunable porous structure in a simple and cost-effective way is a great challenge. Here, mechanical pressure is proposed to tune the porosity of surface-oxidized copper foams that realize the tunable porosity and surface affinity to lithium simultaneously. These foams exhibit enhanced electrochemical performances as the host for Li metal anodes. They can run 5000 cycles at 5 mA cm−2 for 1 mAh cm−2 in symmetrical cells, much better than the cases without pressure regulation or without surface oxidization. It is one of the best results reported so far using copper structures as the current collector for Li metal anodes. The full cells paired with LiFePO4 or with LiNi0.5Co0.3Mn0.2O2 also demonstrate their advantages than those without surface oxidization or without compression. These results indicate the promising potential of these foams as a host for dendrite-free Li metal anodes.