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 mAhg1, 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.