Synergistic effect of interface layer and mechanical pressure for advanced Li metal anodes

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 Li3P/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 Li3P/LiCl-coated Li//LiFePO4, 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.