Silicon Layer on Polymer Electrolyte as a Dendrite Stopper for Stable Lithium Metal Batteries

Silicon (Si) is a promising candidate for next-generation anode materials because of its high specific capacity of 3579 mAh g–1 and low potential of 0.4 V (vs Li+/Li). However, the development of Si anode has been limited by the huge volume expansion during the lithiation process. Here, a layer of core–shell Si@SiOx nanoparticles is coated on one surface of the polymer electrolyte as a dendrite stopper by taking advantage of the high specific capacity of Si, and the negative effects of Si volume expansion can be offset by the flexibility of the polymer electrolyte. The Si@SiOx layer is employed to match the lithium metal anode for suppressing the growth of lithium dendrites. When lithium dendrites are in contact with the Si@SiOx layer, the Si@SiOx nanoparticles can react with lithium ions deposited on the contact interface to form a Li–Si alloy (LiySi), which can reduce the concentration of lithium ions at the sharp ends of lithium dendrites, thus inhibiting the further growth of lithium dendrites. As a result, symmetric Li//Li cells can maintain stability without lithium dendrites for more than 2600 h. This study presents a promising approach to address the dendrite issue in solid-state lithium metal batteries.