Small‐Dipole‐Molecule‐Containing Electrolytes for High‐Voltage Aqueous Rechargeable Batteries

Abstract

The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.202106180.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 energystorage systems.

Efficient Ammonia Electrosynthesis and Energy Conversion through a Zn‐Nitrate Battery by Iron Doping Engineered Nickel Phosphide Catalyst

“…To summarize, the Zn-NO 3 battery system broadens the field of Zn-based batteries. [44][45][46][47] To verify the NH 3 produced in our experiments indeed originated from NO 3 electroreduction, several comparison tests were carried out. Blank K 2 SO 4 solution and K 2 SO 4 /NO 3 solution show little to no NH 3 before the electrolysis.…”

Hydrogen‐Bond Disrupting Electrolytes for Fast and Stable Proton Batteries

“…On the other hand, in the solvent sheath (a complex of hydronium ions and solvent molecular ligand or anion ligand), glycerol molecules with the higher negative charge density oxygen are easier to connect with hydronium ions and deplete water molecules inside the solvation sheath, which can improve the electrochemical stability of water molecules and increase the potential window of glycerol‐contained electrolytes. [ 31 ]…”

“…As the glycerol concentration increases, glycerol molecules initially disrupt the hydrogen bonds of water molecules out of the H 3 O + sheath with the formation of strong glycerol–water hydrogen bonds (Figure 4b), and then gradually insert into the outer sheath of hydronium ions. [ 36 ] Because glycerol is more nucleophilic property (owning stronger Lewis alkalinity) than water, [ 31 ] glycerol molecules are better at donating electrons, and deplete water molecules inside the primary solvation sheath as the concentration further increases. This is also confirmed by the aforementioned FTIR spectra and MD simulations analysis in Figure 1.…”

“…On the other hand, in the solvent sheath (a complex of hydronium ions and solvent molecular ligand or anion ligand), glycerol molecules with the higher negative charge density oxygen are easier to connect with hydronium ions and deplete water molecules inside the solvation sheath, which can improve the electrochemical stability of water molecules and increase the potential window of glycerol-contained electrolytes. [31] Molecular dynamics (MD) simulations were then carried out to analyze the solvation structure of pure H 2 SO 4 and H 2 SO 4glycerol systems. The radial distribution functions (RDFs) and coordination number analysis were obtained (Figure 1g,h).…”

Recent advances and future perspectives for aqueous zinc-ion capacitors

“…The super-concentrated sugar electrolyte can expand the ESW to over 2 V and when it was applied in aqueous ion hybrid capacitors, the specific energy and Coulombic efficiency were effectively improved [112]. In addition, small dipole molecule-containing electrolytes are promising choices for high-voltage aqueous energy storage devices [113]. The introduction of various additives [85,94] could induce the formation of SEI and optimize the solvation sheath structure, thus to reduce the overpotential during the deposition process of zinc in ZIC, which has already been introduced in the zinc anode part.…”