Small‐Dipole‐Molecule‐Containing Electrolytes for High‐Voltage Aqueous Rechargeable Batteries. Issue 4 (28th November 2021) - Huang, Zhaodong
Abstract: High‐voltage aqueous rechargeable batteries are promising competitors for next‐generation energy storage systems with safety and high specific energy, but they are limited by the absence of low‐cost aqueous electrolytes with a wide electrochemical stability window (ESW). The decomposition of aqueous electrolytes is mainly facilitated by the hydrogen bond network between water molecules and the water molecules in the solvation sheath. Here, three types of small dipole molecules (small molecules containing a dipole; glycerol (Gly), erythritol (Et), and acrylamide (AM)) are reported to develop aqueous electrolytes with high safety and wide ESW (over 2.5 V) for aqueous lithium‐, sodium‐, and zinc‐ion batteries, respectively. The solvation‐sheath structures are explored by ab initio molecular dynamics (MD) simulations, demonstrating that three types of dipole molecules deplete the water molecules in the solvation sheath of the charge carrier and break the hydrogen bond network between the water molecules, thus effectively expanding the ESW. A battery constructed from lithium titanate and lithium manganate in Gly‐containing electrolyte exhibits an output voltage of 2.45 V and retains a specific capacity of 119.6 mAh g −1 after 400 cycles. This work provides another strategy for exploiting low‐cost high‐voltage electrolytes for aqueous energy‐storage systems. Abstract : Three kinds of small‐dipole‐molecule‐containing electrolytes are developed for aqueous batteries. The developed electrolytes deliver an expanded electrochemical stability window (over 2.5 V), and their solvation‐sheath structure and ion conductivity mechanism are explored. A constructed Li4 Ti5 O12 //LiMn2 O4 battery in a glycerol‐containing electrolyte exhibits high output voltage (2.45 V) and a specific capacity of 119.6 mAh g −1 after 400 cycles.