Ion‐Conductive Polytitanosiloxane Networks Enable a Robust Solid‐Electrolyte Interface for Long‐Cycling Lithium Metal Anodes

Abstract Despite a high‐energy density and low reduction potential, the use of Li metal batteries is hampered by their insufficient electrochemical sustainability, which mainly stems from the lack of a reliable solid‐electrolyte interphase (SEI). In this study, a robust SEI connected by polytitanosiloxane (PTS) is constructed via the in situ condensation reaction between tetraethyl orthosilicate/tetraethyl orthotitanate (TEOS/TEOT) electrolyte additives and the Li anode. In PTS, the Si‒O‒Si bonds, which have a low ion diffusion barrier, can provide an Li + transport pathway to ensure regular Li deposition. Moreover, the 3D crosslinked PTS skeleton with strong Si‒O‒Ti linkages relieves the strain of volume variations and maintains the integrity of the SEI under Li stripping/plating cycles. The resulting Li|LiFePO 4 cell with TEOS/TEOT electrolyte additives exhibits ultra‐stable cycling performance over 3000 cycles with an extremely low capacity decay rate of 0.008% per cycle. This study of the TEOS/TEOT as synergetic electrolyte additives offers a new method for regulating the interfacial properties of Li anodes.