Stable Cycling of Sodium Metal Anodes Enabled by a Sodium/Silica‐Gel Host

Sodium metal batteries (SMBs) are innovative and promising energy storage systems. SMBs are a competitive technological paradigm compared to the state‐of‐the‐art lithium‐ion batteries thanks to the high specific capacity of sodium metal, i. e., 1166 mAh g−1, and the Na+/Na0 low redox potential of −2.71 V vs. standard hydrogen electrode. Unstable solid electrolyte interface (SEI), uncontrolled overpotentials and dendrite growth of sodium are the main drawbacks that hinder the development of SMBs. Herein, we propose a functionalized silica gel material with extended porosity (NaSGII) as an active host material in order to obtain stable cycling of sodium metal anodes. NaSGII was incorporated in composite electrodes using a conductive carbon additive and polymeric binders and the functional properties in SMBs cells demonstrated by galvanostatic tests. A Butler‐Volmer analysis demonstrated an improvement of electrokinetic parameters induced by NaSGII. Cycling more: A composite material with Na4Si4 and Na2SiO3 nanocrystals, NaSGII, was successfully used as host material for sodium deposition and dissolution in aprotic sodium metal batteries (SMBs). Improved electro‐kinetics of the process, stable cycling and low overpotentials are achieved, demonstrating that NaSGII has promising features for its employment in the field of SMBs.