Rechargeable aqueous electrolyte batteries: from univalent to multivalent cation chemistry

Abstract

Featuring the most recent advances and challenges in aqueous electrolyte metal-ion battery systems and understanding the cell chemistries and different behaviours in aqueous and non-aqueous media.

Defect Engineering in Manganese‐Based Oxides for Aqueous Rechargeable Zinc‐Ion Batteries: A Review

“…Most importantly, by using aqueous electrolyte in the battery can enhance the safety for both the consumers and for the environment. [ 7–14 ] Among the reported aqueous rechargeable battery technologies, zinc‐ion battery (ZIB) is probably the most widely studied due to the numerous advantages that Zn anode possesses. For instance, Zn is known to be stable in neutral electrolyte.…”

A High Energy Density Aqueous Battery Achieved by Dual Dissolution/Deposition Reactions Separated in Acid‐Alkaline Electrolyte

“…The Zn–Mn 2+ cells using the catholyte containing different concentrations of sulfuric acid were assembled, which were then tested at the mode of potentionstatically charging (2.65 V) and galvanostatically discharging (2 mA cm −2 ) ( Figure 3 a). The cell using 0.5 m acid electrolyte exhibits the highest CE of 98.4% among all the concentrations, which is due to the following reasons: first, when the concentration of proton is low (0.1 m H 2 SO 4 ), the discharge reaction of cathode will partly change into proton reaction (MnO 2 +H + + e − ↔MnOOH, correspond to the 2 V platform of 0.1 m H 2 SO 4 shown in Figure 3a) rather than the MnO 2 dissolution, which is a single electron transfer reaction, thus leading to lower CE; however, as the concentration of proton increases, the potential of OER starts to be lower than MnO 2 deposition reaction, thereby causing certain side reaction of water decomposition in the battery and then worse CE. The critical concentration of proton for the equal potential of OER and MnO 2 deposition reaction is 0.83 m based on the Nernst equation (detailed calculation process is shown in the Supporting Information).…”

“…Energy Mater. 2020, 10,1903589 of cathode will partly change into proton reaction (MnO 2 +H + + e − ↔MnOOH, correspond to the 2 V platform of 0.1 m H 2 SO 4 shown in Figure 3a) rather than the MnO 2 dissolution, [14] which is a single electron transfer reaction, thus leading to lower CE; however, as the concentration of proton increases, the potential of OER starts to be lower than MnO 2 deposition reaction, [19] thereby causing certain side reaction of water decomposition in the battery and then worse CE. The critical concentration of proton for the equal potential of OER and MnO 2 deposition reaction is 0.83 m based on the Nernst equation (detailed calculation process is shown in the Supporting Information).…”

“…The low energy densities are mainly due to the voltage limit of aqueous electrolytes. The root of the low voltages of aqueous batteries is the narrow electrochemical window of water, limited by the hydrogen and oxygen evolution reactions (HER and OER) of the water decomposition, thus the stable voltage window of aqueous electrolytes with a constant pH is as narrow as 1.23 V. [9] To broaden the electrochemical window, a "water in salt" electrolyte has been designed. It has an electrochemical window of more than 3 V by dissolving ultrahigh concentration (21 m) of expensive salt in water, which effectively reduces the water electroactivity and modulates redox potentials.…”

Dendrites issues and advances in Zn anode for aqueous rechargeable Zn‐based batteries

“…The ion movement driven by the electric field is strongly influenced by the mass transfer process near the interface when deposition occurs, including the electrolyte, interfacial layer, and separator. By altering electrolyte components and concentration, a uniform ion migration behavior and less polarization will reach the dendrite suppression 57 . The electrolyte can be generally divided into aqueous and nonaqueous electrolytes (including ion liquid electrolytes and organic liquid electrolytes).…”