Constructing a High-Strength Solid Electrolyte Layer by In Vivo Alloying with Aluminum for an Ultrahigh-Rate Lithium Metal Anode

The serious safety issues caused by uncontrollable lithium (Li) dendrite growth, especially at high current densities, seriously hamper the rapid charging of Li metal-based batteries. Here, the construction of Al-Li alloy/LiCl-based Li anode (ALA/Li anode) is reported by displacement and alloying reaction between an AlCl3-ionic liquid and a Li foil. This layer not only has high ion-conductivity and good electron resistivity but also much improved mechanical strength (776 MPa) as well as good flexibility compared to a common solid electrolyte interphase layer (585 MPa). The high mechanical strength of the Al-Li alloy interlayer effectively eliminates volume expansion and dendrite growth in Li metal batteries, so that the ALA/Li anode achieves superior cycling for 1600 h (2.0 mA cm(-2)) and 1000 cycles at an ultrahigh current density (20 mA cm(-2)) without dendrite formation in symmetric batteries. In lithium-sulfur batteries, the dense alloy layer prevents direct contact between polysulfides and Li metal, inhibiting the shuttle effect and electrolyte decomposition. Long cycling performance is achieved even at a high current density (4 C) and a low electrolyte/sulfur (6.0 mu L mg(-1)). This easy fabrication process provides a strategy to realize reliable safety during the rapid charging of Li-metal batteries.