High voltage and superior cyclability of indium hexacyanoferrate cathodes for aqueous Na-ion batteries enabled by superconcentrated NaClO₄ electrolytes

Abstract

Highly-concentrated aqueous NaClO4 electrolyte enables the high working voltage and superior cyclability of NaIn[Fe(CN)6]. Furthermore, a guideline for tuning the working potential of Prussian Blue Analogs is demonstrated.

Mechanisms of Degradation of Na2Ni[Fe(CN)6] Functional Electrodes in Aqueous Media: A Combined Theoretical and Experimental Study

“…This finding strongly indicates the detrimental effect of some anions and their notable role in promoting electrode dissolution. The order of electrode stability as a function of the involved anion is also in great agreement with previous findings for other PBA materials, namely, NaIn­[Fe­(CN) 6 ] and K 2 Cr­[Fe­(CN) 6 ]. , …”

“…Lastly, we investigate the effect of the electrolyte concentration on electrode stability. It has been shown in previous works on PBAs that the dissolution of active material can be suppressed by increasing the concentration of the electrolyte toward the so-called water-in-salt electrolytes. ,, NaClO 4 has proven to be a promising candidate for this approach as concentrations beyond 10 M are feasible for this salt. , Figure shows the stability of NiHCF electrodes in varying concentrations from 0.25 to 8 M NaClO 4 . The stability slightly decreases when raising the concentration from 0.25 to 1 M, while a significant stabilization of the material can be observed above 2 M with almost no degradation for an 8 M NaClO 4 solution.…”

“…It has been shown in previous works on PBAs that the dissolution of active material can be suppressed by increasing the concentration of the electrolyte toward the so-called water-in-salt electrolytes. 29,57,66 NaClO 4 has proven to be a promising candidate for this approach as concentrations beyond 10 M are feasible for this salt. 66,67 Figure 6 shows the stability of NiHCF electrodes in varying concentrations from 0.25 to 8 M NaClO 4 .…”

“…The order of electrode stability as a function of the involved anion is also in great agreement with previous findings for other PBA materials, namely, NaIn[Fe(CN) 6 ] and K 2 Cr[Fe(CN) 6 ]. 57,58 Hypothesizing that the degradation process is initiated by the adsorption of anions from the electrolyte on the metal centers of the NiHCF surface, the adsorption strength and, therefore, the impact of the individual anions should differ considering their distinct geometry, size, charge density, and polarity. To quantify this effect, we examine the adsorption energetics for ClO 4…”

A Physical Impedance Model of Lithium Intercalation into Graphite Electrodes for a Coin‐Cell Assembly

“…In this work, we develop a physical model based on the three-step mechanism. [23][24][25][26][27][28] This model describes the adsorption/desorption reactions of the lithium ions on a graphite electrode. Moreover, we supported the results of these findings with direct current measurements.…”