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 LiFePO 4 or with LiNi 0.5 Co 0.3 Mn 0.2 O 2 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.
Porous carbon materials (PCMs) with high specific surface area (SSA) exhibit significant potential for hydrogen storage applications but are severely limited due to the weak interactions of H 2 . In this work, polyvinylpyrrolidone (PVP) was employed to prepare PCMs with ultra-high SSA and high micropore ratio through applying mechanical pressure before activation. This approach resulted in an SSA exceeding 3100 m 2 /g and a maximum S BET /S Micro ratio above 90%. The increased microporosity significantly improved hydrogen storage performance, with a 62% increase in hydrogen uptake capacity per SSA at 77 K and 50 bar-H 2 , suggesting the strengthened interaction between PCMs and H 2 . This is further supported by the increased isosteric heat of hydrogen adsorption (Q st ) values from 6.93 to 7.56 kJ/mol at near-zero hydrogen coverage, with S Micro /S BET increasing from 75.86% to 90.83%. Moreover, the increased microporosity enhances the volumetric and usable hydrogen storage capacity. Remarkably, the PCM with 84.35% microporosity and high SSA of 3116.58 m 2 /g exhibits a hydrogen uptake of 6.10 wt% (26.47 g/L) at 77 K under 50 bar-H 2 , and retains 1.26 wt% (5.52 g/L) even at 298 K and 130 bar-H 2 . This study provides a valuable reference for the large-scale preparation of PCMs with high SSA and microporosity for hydrogen storage.
Li metal anodes as one of promising anodes in next-generation batteries , face the challenges from infinite volume change and high reactivity to electrolytes that easily leads to unstable Li/electrolyte interface and unique dendrite growth of Li. Although mechanical pressure can effectively inhibit the dendrite growth of Li, it also increases the risk of short circuits, because Li metal easily grows into the separator under pressure. Here, an interface layer is introduced on Li metal to block this growth, using Li 3 P/LiCl as a model. Meanwhile, the dense and robust layer also reduce the side reactions between Li and electrolytes. With the helps from mechanical pressure and interface layer , this design exhibits the improved electrochemical performances, much better than that without pressure or without the layer. The full cells of Li 3 P/LiCl-coated Li//LiFePO 4 , show a capacity of 1.69 mAh cm −2 after 1000 cycles under pressure at 3.9 mA cm −2 with a capacity retention of 99.5% in carbonates. The results indicate the promising potential for the pressure effect to be used for advanced Li metal anodes .
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