Advanced Aqueous Ammonium-Ion Batteries Enabled by Hydrogen Bond Modulation

Aqueous ammonium-ion batteries (AAIBs) are promising for large-scale energy storage but suffer from side reactions originating from electrolytes, such as water decomposition. Herein, we propose a H-bond network modulation strategy by using ethylene glycol (EG) as electrolyte additive to resolve this issue and realize high-performance AAIBs. EG is chosen because of its rich hydroxyl groups that can form H-bonds with water molecules and suppress water decomposition. Moreover, the modulated water–EG H-bond network benefits the fast migration of NH4+, resulting in the enhanced ionic conductivity. As a proof of concept, a PTCDI//CuHCF AAIB is fabricated and delivers a high capacity of 70.4 mAh g–1 at 0.3 A g–1, a satisfactory cycle stability of 82.8% capacity retention after 500 cycles, and high energy density of 63.1 Wh kg–1 at 262.7 W kg–1. This work presents a novel electrolyte modulation strategy toward the practical application of AAIBs.