In-situ hydrophobic protective layer for suppressing hydrogen evolution corrosion and enabling high-efficiency silicon-air batteries with wide temperature adaptability

Silicon (Si), with its high theoretical capacity, highly negative redox potential (−1.69 V vs. SHE), abundance, and low cost, has attracted widespread attention as an anode material for air batteries. However, the specific electric double layer (EDL) between the Si anode and electrolyte causes severe hydrogen evolution corrosion, resulting in a significant deviation of the specific capacity from its theoretical value. To address this issue, a low-cost and high-efficiency additive strategy was developed. By introducing a small amount of dodecyl dimethyl benzyl ammonium bromide (DDBAB), which features a (C₂H₅)₂N⁺ group that strongly interacts with OH⁻, and a hydrophobic C₁₂H₂₅ and C₂H₅, the EDL is altered and an in-situ hydrophobic protective layer is formed. This layer effectively repels active H₂O from the Si anode/electrolyte interface and increases the barriers to hydrogen evolution reactions (HER). As a result, the hydrogen evolution inhibition efficiency of Si anode reached 99.36 %. The aqueous silicon-air batteries (SABs) lasted from 173 h to 500 h, and the energy density and specific capacity enhanced by 2.6-fold and 2.7-fold, respectively. Due to the temperature-insensitive binding energy between DDBAB and the Si anode, the quasi-solid-state SABs (QSSSABs), using PAAK-M gel electrolyte, as a proof of concept, exhibit a high specific capacity of 324.54 Ah kg⁻¹, excellent stability across a wide temperature range (−10 °C to 60 °C), and great application potential.