Common ion effect enhanced Prussian blue analogues for aqueous ammonium ion storage

Abstract

In order to meet the growing applications of energy storage for power grid, aqueous NH4+ batteries are attracting increasing attention as a promising alternative due to its environmental significance, abundant...

The Emergence of Aqueous Ammonium‐Ion Batteries

“…Besides changing the type of salt, the properties of the electrolyte can be further modified by controlling the salt concentration or by adding additives to enhance the performance of the AAIB. [35,38,53] Highly concentrated electrolytes or water-in-salt electrolytes (WiSEs) have attracted much attention on account of their merits,such as enabling awide ESW,inhibiting parasitic side reactions,a nd suppressing active material dissolution. [81] Forexample,the Ji group reported aWiSE composed of 25 m NH 4 Ac which showed aESW that was broadened to 2.95 Vin 25 m NH 4 Ac compared to 2.25 Vi n1 m NH 4 Ac (Figure 7a).…”

“…[29] TheShu group has proven that the addition of functional additives to the electrolyte is as uccessful strategy.S pecifically,0.1m Fe 2 (SO 4 ) 3 was added to the NH 4 (SO 4 ) 2 electrolyte, which enabled the FeHCF cathode to operate with ah igh capacity retention of 96.3 %a fter 1000 cycles. [38] Thei mproved performance was attributed to the so-called "common Reproducedf rom Ref. [53] with permission from Elsevier.…”

“…[53] Moreover,l imited amounts of additives were included to stabilize the electrode materials through the "common ion effect". [38] From conventional aqueous liquid electrolytes, hydrogel electrolytes can also be obtained by adding poly-mers,for example,P AM [60] and PVA, [87] which may accelerate the development of flexible NH 4 + storage devices.D espite such promising results,m any aspects regarding the nature of the interphases generated by such electrolytes remain elusive. Further studies are encouraged to understand the composition and properties of solid-electrolyte interphases by using, for example,X PS,s oft X-ray absorption spectroscopy,t ransmission electron microscopy,and electrochemical impedance spectroscopy.I na ddition, the solvated structure of these electrolytes requires further investigation to elucidate the role of the unique tetrahedral structure of NH 4 + ions.I nt his context, the combination of theoretical methods (e.g.m olecular dynamics simulations) and experimental techniques (e.g.…”

The Emergence of Aqueous Ammonium‐Ion Batteries

“…Additionally, the anion would also have a distinct influence on the solvation structure of the cation, as well as lead to an anion‐derived solid electrolyte interphase (this aspect has yet to be investigated). Besides changing the type of salt, the properties of the electrolyte can be further modified by controlling the salt concentration or by adding additives to enhance the performance of the AAIB [35, 38, 53] …”

“…In addition to the conventional dilute electrolytes, highly concentrated NH 4 Ac with a widened ESW has been proposed and has led to an improved performance [53] . Moreover, limited amounts of additives were included to stabilize the electrode materials through the “common ion effect” [38] . From conventional aqueous liquid electrolytes, hydrogel electrolytes can also be obtained by adding polymers, for example, PAM [60] and PVA, [87] which may accelerate the development of flexible NH 4 + storage devices.…”